Method for the industrial production of an alkaline earth metal compound which is not an alkaline earth metal sulphate, corresponding production plant, corresponding uses, corresponding kit and corresponding use of a kit

Abstract

The invention relates to a method for the industrial production of an alkaline earth metal compound which is not an alkaline earth metal sulphate, at least comprising the following steps: S1) (i) producing or providing an alkaline earth metal sulphate and separately (ii) producing or providing a reduction gas; S2) reducing the alkaline earth metal sulphate produced or provided in step S1) by means of the reduction gas such that a corresponding alkaline earth metal sulphide results.

Description

[0001] Kandelium Barium Strontium GmbH & Co. KG

[0002] At the freight yard, 53557 Bad Hönningen

[0003] Fraunhofer Society for the Advancement of Applied Research, registered association, Hansastraße 27c, 80686 Munich

[0004] Method for the industrial production of an alkaline earth metal compound other than an alkaline earth metal sulfate, corresponding production plant, corresponding uses, corresponding kit and corresponding use of a kit

[0005] The present invention relates to a process for the industrial production of an alkaline earth metal compound other than an alkaline earth metal sulfate. The present invention also relates to a production plant for the production of an alkaline earth metal compound other than an alkaline earth metal sulfate. The present invention further relates to the use of hydrogen and / or methane in a process for the production of an alkaline earth metal compound other than an alkaline earth metal sulfate. The present invention further relates to a kit for the production of an alkaline earth metal compound other than an alkaline earth metal sulfate. The present invention also relates to the use of such a kit.

[0006] The present invention lies in the field of the industrial production of alkaline earth metal compounds that are not alkaline earth metal sulfates. Such alkaline earth metal compounds differ fundamentally in their properties and industrial production from metals such as iron, aluminum, copper, gold, and others. It is of the expertise of the specialist

[0007] *20250496986* It is known that the knowledge from the industrial manufacturing processes of these metals, in particular the knowledge from the industrial manufacturing processes of iron from iron ore, cannot be transferred to the industrial production of alkaline earth metal compounds that are not alkaline earth metal sulfates without an unreasonable effort.

[0008] Furthermore, the industrial production (i.e., production of more than 100 kg per hour) of alkaline earth metal compounds other than alkaline earth metal sulfates differs fundamentally in its requirements from the production of corresponding compounds on a laboratory scale (i.e., production of a few mg per hour up to 1000 g per hour).It is known to those skilled in the art that scaling up a manufacturing process from laboratory scale to an industrial manufacturing process is regularly associated with complex development steps; for example, they are aware that the material distribution in the reaction chamber, the transport of reactants and products in the reaction chamber, the spatial distribution of heat generation in the reaction chamber, the implementation of possible cooling and / or heating steps in the reaction chamber, the distribution of additionally supplied reactants in the reaction chamber, the control of reaction kinetics and additional factors in industrial manufacturing processes differ fundamentally from those on a laboratory scale.

[0009] The industrial production of alkaline earth metal compounds that are not alkaline earth metal sulfates is carried out according to the prior art starting from the respective alkaline earth metal sulfates by reducing the alkaline earth metal sulfates with solid coke (carbon / petroleum coke) to the corresponding alkaline earth metal sulfides and subsequently processing the alkaline earth metal sulfides into the desired alkaline earth metal compounds.

[0010] The industrial production of alkaline earth metal compounds other than alkaline earth metal sulfates is currently associated with CO2 production, which is increasingly considered problematic in the field of the present invention due to the climate-damaging effects of CO2. Therefore, there is a need for processes for the industrial production of alkaline earth metal compounds other than alkaline earth metal sulfates that release as little CO2 as possible during production. In particular, there is also a need for processes for the industrial production of alkaline earth metal compounds other than alkaline earth metal sulfates that release no CO2 at all during production.There is also a need for processes for the industrial production of alkaline earth metal compounds that are not alkaline earth metal sulfates, which can be carried out using readily available starting materials in sufficient quantities.

[0011] There is also a need for processes for the industrial production of alkaline earth metal compounds that are not alkaline earth metal sulfates, whereby no additional process steps involving disproportionately high costs are required compared to the processes known from the prior art.

[0012] Capturing and subsequently storing the CO2 produced is often associated with an undesirably high level of effort and is therefore undesirable in many cases in the field of the present invention.

[0013] There is also a need for processes for the industrial production of alkaline earth metal compounds that are not alkaline earth metal sulfates, in which a reducing agent is used, the transport of which to the place of process execution is carried out with the lowest possible CO2 emissions.

[0014] There is also a need for processes for the industrial production of alkaline earth metal compounds other than alkaline earth metal sulfates, in which the resulting intermediate products can be purified with minimal equipment and / or time expenditure. In particular, there is a need for processes for the industrial production of alkaline earth metal compounds other than alkaline earth metal sulfates in which the resulting intermediate products do not require any purification at all, but can be processed further without purification.

[0015] There is also a need for processes for the industrial production of alkaline earth metal compounds other than alkaline earth metal sulfates, in which the resulting alkaline earth metal compounds (other than alkaline earth metal sulfates) can be purified with minimal equipment and / or time expenditure. In particular, there is a need for processes for the industrial production of alkaline earth metal compounds (other than alkaline earth metal sulfates) in which the resulting alkaline earth metal compounds (other than alkaline earth metal sulfates) do not require any purification at all, but can be used as the final product without purification.

[0016] Furthermore, there is a need for processes for the industrial production of alkaline earth metal compounds other than alkaline earth metal sulfates that avoid as many of the aforementioned problems as possible and meet as many of the aforementioned needs as possible, without having to use other alkaline earth metal-containing starting materials than those known from the prior art of processes for the production of alkaline earth metal compounds other than alkaline earth metal sulfates.

[0017] Furthermore, there is a need for processes for the industrial production of alkaline earth metal compounds that are not alkaline earth metal sulfates, which avoid as many of the aforementioned problems as possible and fulfill as many of the aforementioned requirements as possible, without requiring undesirably complex chemical and / or mechanical processing of the alkaline earth metal-containing starting materials used.

[0018] A primary objective of the present invention was to provide a process for the industrial production of alkaline earth metal compounds that are not alkaline earth metal sulfates, wherein the aforementioned problems do not occur or only occur to a reduced extent, or the aforementioned requirements are met as advantageously as possible.

[0019] The invention is defined in the appended claims. Preferred aspects of the present invention will also become apparent from the following description, including the examples. Where certain embodiments are designated as preferred for an aspect of the invention (process for the industrial production of an alkaline earth metal compound other than an alkaline earth metal sulfate, production plant for the production of an alkaline earth metal compound other than an alkaline earth metal sulfate, use of hydrogen and / or methane in a process for the production of an alkaline earth metal compound other than an alkaline earth metal sulfate, kit for the production of an alkaline earth metal compound other than an alkaline earth metal sulfate, use of a corresponding kit), the corresponding embodiments shall also apply, mutatis mutandis, to the other aspects of the present invention.Preferred individual features of aspects of the invention (as defined in the claims and / or disclosed in the description) can be combined with each other and are preferably combined with each other, unless otherwise apparent to the person skilled in the art from the present text in the individual case.

[0020] Likewise, the disadvantages of the prior art mentioned above also apply to the other aspects of the present invention; the considerations set forth above regarding various problems apply accordingly. The primary problem of the present invention, as well as related further problems, are solved by a process for the industrial production of an alkaline earth metal compound that is not an alkaline earth metal sulfate, comprising at least the following steps:

[0021] 51) (i) Manufacture or provision of an alkaline earth metal sulfate, preferably barium sulfate and / or strontium sulfate; and separately therefrom

[0022] (ii) Production or supply of a reducing gas;

[0023] 52) Reducing the alkaline earth metal sulfate produced or provided in step S1), preferably the barium sulfate and / or strontium sulfate produced or provided in step S1), using the reducing gas, so that a corresponding alkaline earth metal sulfide, preferably barium sulfide and / or strontium sulfide, results.

[0024] A preferred method is (as described above, preferably referred to as preferred above) wherein, in step S2), in addition to the alkaline earth metal sulfide, preferably barium sulfate and / or strontium sulfate, an alkaline earth metal oxide is obtained, preferably a barium oxide (BaO) and / or a strontium oxide (SrO).

[0025] Within the scope of the present invention, a process for industrial production is preferably a process with a production quantity of alkaline earth metal compound, which is not an alkaline earth metal sulfate, of at least 101 kg / h, preferably at least 500 kg / h, particularly preferably at least 13000 kg / h.

[0026] Surprisingly, it has been shown that a process using alternative solid reducing agents and / or liquid reducing agents does not lead to similarly advantageous combinations of properties.

[0027] In the context of this text, the term "alkaline earth metal sulfate" refers, in accordance with the usual understanding of those skilled in the art, to one of the compounds selected from the group consisting of: beryllium sulfate (BeSC), magnesium sulfate (MgSC), calcium sulfate (CaSC), strontium sulfate (SrSC), barium sulfate (BaSC), radium sulfate (RaSC), and mixtures thereof. Preferably, in the context of the present invention, an alkaline earth metal sulfate is strontium sulfate (SrSC) or barium sulfate (BaSC).

[0028] Within the context of this text, the term "alkaline earth metal sulfide" refers, in accordance with the usual understanding of those skilled in the art, to one of the compounds selected from the group consisting of: beryllium sulfide (BeS), magnesium sulfide (MgS), calcium sulfide (CaS), strontium sulfide (SrS), barium sulfide (BaS), radium sulfide (RaS), and mixtures thereof. Preferably, within the scope of the present invention, an alkaline earth metal sulfide is a strontium sulfide (SrS) or a barium sulfide (BaS).

[0029] An “alkaline earth metal compound other than an alkaline earth metal sulfate” is, in accordance with the usual technical understanding, a compound of at least one of the metals selected from: beryllium, magnesium, calcium, strontium, barium and radium with at least one other substance not selected from the foregoing list of metals, wherein the “alkaline earth metal compound other than an alkaline earth metal sulfate” is not a compound selected from the group consisting of: beryllium sulfate (BeSO4), magnesium sulfate (MgSO4), calcium sulfate (CaSO4), strontium sulfate (SrSO4), barium sulfate (BaSO4), radium sulfate (RaSO4) and mixtures thereof.

[0030] In the context of the present invention, a reducing gas is defined as a gaseous substance capable of reducing an alkaline earth metal sulfate, preferably barium sulfate and / or strontium sulfate, to an alkaline earth sulfide, preferably barium sulfide and / or strontium sulfide, at a temperature in the range of 700 °C to 1000 °C, preferably in the range of 900 °C to 980 °C, particularly preferably in the range of 930 °C to 960 °C, and most preferably at a temperature of 950 °C. A reducing gas is a substance that donates electrons and thereby reduces the alkaline earth metal sulfate to the alkaline earth sulfide.

[0031] The fact that an aqueous solution containing a dissolved alkaline earth metal sulfide results in step S3) means that the aqueous solution contains solvated Ba 2+ includes ions.

[0032] Surprisingly, it has been found that alkaline earth metal compounds other than alkaline earth metal sulfates can be produced using the industrial process according to the invention without the formation of CO2 and without the need for prior chemical processing of the alkaline earth metal sulfate used as a starting material (and used as a starting material in processes known in the art for the production of alkaline earth metal compounds other than alkaline earth metal sulfates). With the process according to the invention for the industrial production of alkaline earth metal compounds other than alkaline earth metal sulfates, alkaline earth metal compounds other than alkaline earth metal sulfates are produced—in many cases preferably without the production of CO2—and, compared to processes known in the art, no additional process steps involving disproportionately high costs are required.

[0033] By using a reducing gas as a reducing agent (i.e., a gaseous reducing agent), the process according to the invention employs a reducing agent whose transport to the process location is preferably carried out by means of a pipeline, so that the transport of the reducing agent to the process location is carried out with the lowest possible CO2 emissions. In particular, the transport of solids as reducing agents is regularly associated with a disadvantageously higher emission (direct or indirect) of CO2.

[0034] The alkaline earth metal sulfide resulting in step S2) of the process according to the invention can be used in the further process without purification. Accordingly, the equipment required for purifying the alkaline earth metal sulfide as a product and / or intermediate, which is regularly considered a disadvantage in the field of the present invention, is not necessary. Likewise, the time required for purifying the alkaline earth metal sulfide as a product and / or intermediate, which is regularly considered a disadvantage in the field of the present invention, is also not necessary.

[0035] A preferred method is (as described above, preferably as referred to above as preferred), wherein the alkaline earth metal compound that is not an alkaline earth metal sulfate is selected from the group consisting of:

[0036] - Barium carbonate

[0037] - Barium soaps,

[0038] Barium sulfonates

[0039] Bariumtitanat (BaTiCh), - Bariumferrit (BaFei2Oi9),

[0040] - Bariumchlorat (Ba(CIC>3)2),

[0041] - Bariumchlorid (BaCL),

[0042] - Lithopone (BaSC ZnS), - Bariumhydroxid (Ba(OH)2),

[0043] - Bariumoxid (BaO),

[0044] - Bariumoxalat (BaC2C>4),

[0045] - Bariumacetat (Ba(C2H3C>2)2),

[0046] - Bariumchromat (BaCrC ), - andere Bariumverbindungen,

[0047] - Strontiumcarbonat,

[0048] - Strontiumseifen,

[0049] - Strontiumsulfonate,

[0050] - Strontiumtitanat (SrTiCh), - Strontiumferrit (SrFei2Oi9),

[0051] - Strontiumchlorat (Sr(CIC>3)2),

[0052] - Strontiumchlorid (SrCL),- Strontiumhydroxid (Sr(OH)2),

[0053] Strontiumoxid (SrO), - Strontiumoxalat (SrC2C>4),

[0054] - Strontiumacetat (Sr(C2H3C>2)2),

[0055] - Strontium chromate (SrCrC ), and - other strontium compounds.

[0056] Particularly preferred is a process (as described above, preferably as referred to above as preferred) wherein the alkaline earth metal compound, which is not an alkaline earth metal sulfate, is selected from the group consisting of: - barium carbonate,

[0057] - Barium titanate (BaTiCh),

[0058] - Barium ferrite (BaFei2Oi9),

[0059] - Barium hydroxide (Ba(OH)2),

[0060] - Barium oxide (BaO), - Barium oxalate (BaC2C>4),

[0061] - Barium acetate (Ba(C2H3C>2)2),

[0062] - Barium chromate (BaCrC ),

[0063] - Strontium carbonate

[0064] Strontium titanate (SrTiC), strontium ferrite (SrFei2Oi9),

[0065] - Strontium hydroxide (Sr(OH)2),

[0066] - Strontium oxide (SrO),

[0067] - Strontium oxalate (SrC2C>4), and

[0068] - Strontium acetate (Sr(C2H3C>2)2).

[0069] Particularly preferred is a process (as described above, preferably as referred to above as preferred) wherein the alkaline earth metal compound which is not an alkaline earth metal sulfate is selected from the group consisting of:

[0070] - Barium carbonate,

[0071] - Barium titanate (BaTiOs),

[0072] - Barium ferrite (BaFei2Oi9),

[0073] - Strontium carbonate,

[0074] - Strontium titanate (SrTiOa) and

[0075] - Strontium ferrite (SrFei2Oi9).

[0076] The aforementioned compounds are obtained in a particularly advantageous manner using the method according to the invention. The advantages and effects associated with the method according to the invention are also realized here in a particularly advantageous manner. A preferred method (as described above, preferably designated as preferred above) includes the following additional step:

[0077] 53) Producing an aqueous solution comprising dissolved components of the alkaline earth metal sulfide resulting in step S2), preferably of the barium sulfate and / or strontium sulfate resulting in step S2), such that an aqueous solution comprising a dissolved alkaline earth metal sulfide, preferably dissolved barium sulfide and / or strontium sulfide, is obtained; and / or, preferably “and” with the following additional step:

[0078] 54) Introducing gaseous carbon dioxide into the aqueous solution resulting from step S3) comprising a dissolved alkaline earth metal sulfide, preferably an alkaline earth metal sulfide selected from the group consisting of barium sulfide and strontium sulfide, such that an alkaline earth metal carbonate results and precipitates wholly or partly as a solid; preferably an alkaline earth metal carbonate selected from the group consisting of barium carbonate and strontium carbonate, and such that hydrogen sulfide (H2S) results.

[0079] A preferred method (as described above, preferably as referred to above as preferred) is wherein in step S3) the dissolved alkaline earth metal sulfide, preferably the dissolved barium sulfide and / or the dissolved strontium sulfide, is hydrolyzed in water to barium hydrogen sulfide and barium hydroxide and / or strontium hydrogen sulfide and strontium hydroxide; and / or wherein in step S3) in addition to the dissolved alkaline earth metal sulfide, preferably in addition to the dissolved barium sulfide and / or in addition to the dissolved strontium sulfide, a dissolved alkaline earth metal hydroxide is additionally obtained, preferably a dissolved barium hydroxide (Ba(OH)2) and / or a dissolved strontium hydroxide (Sr(OH)2).

[0080] In many cases, it is preferred that the alkaline earth metal sulfide resulting in step S2) is dissolved in an aqueous solvent, preferably water, as defined in step S3) after its preparation and before further processing. This is particularly preferred if step S4) is to be carried out as the next process step, i.e., if a corresponding alkaline earth metal carbonate is produced from the alkaline earth metal sulfide resulting in step S2) in the process according to the invention.

[0081] The fact that an aqueous solution containing a dissolved alkaline earth metal sulfide results in step S3) means that the aqueous solution contains solvated alkaline earth metal ions, preferably Ba 2+ Ions and / or Sr 2+ includes ions.

[0082] According to the usual understanding of the person skilled in the art, in step S4) barium sulfide results in barium carbonate and strontium sulfide results in strontium carbonate.

[0083] If CO2 results as a product in step S2) of the process according to the invention, this CO2 is preferably used in step S4) so ​​that the release of CO2 in the process according to the invention is minimized, preferably avoided entirely. Depending on the choice of reducing gas, however, no CO2 may be produced at all in step S2), so that the CO2 introduced in step S4) must be produced and / or provided separately.

[0084] The advantages and effects associated with the method according to the invention are also realized here in a particularly advantageous manner.

[0085] A preferred method is (as described above, preferably as referred to above as preferred), wherein the alkaline earth metal sulfate produced or provided in step S1) is selected from the group consisting of: barium sulfate and

[0086] - Strontium sulfate; and / or wherein the reducing gas used in step S2) for the reduction of the alkaline earth metal sulfate is selected from the group consisting of:

[0087] - Hydrogen (H2),

[0088] - Ammonia (NH3),

[0089] - Methane (CH4) and

[0090] Mixtures thereof; and / or the alkaline earth metal sulfide resulting in step S2) is selected from the group consisting of:

[0091] - Barium sulfide and

[0092] - Strontium sulfide; and / or the alkaline earth metal carbonate resulting in step S4) is selected from the group consisting of: barium carbonate (BaCCh) and

[0093] Strontium carbonate (SrCCh).

[0094] Following the usual understanding of the person skilled in the art, in step S2) by way of example, barium sulfate results in barium sulfide and strontium sulfate results in strontium sulfide.

[0095] Following the usual understanding of the person skilled in the art, in step S4) by way of example, barium sulfate results in barium carbonate and strontium sulfate results in strontium carbonate.

[0096] In many cases, it is preferred that the reducing gas used in step S2) for the reduction of the alkaline earth metal sulfate is hydrogen (H2); with the use of hydrogen, the process according to the invention can be carried out entirely without the release of CO2. In many cases, however, the use of ammonia (NH3) is also preferred, for example to enable a less explosive process.

[0097] At the temperatures at which the reduction is carried out, ammonia is in many cases directly cracked into N2 and H2; consequently, a (dilute) Fh atmosphere results in these cases.

[0098] The alkaline earth metal sulfates used in the process according to the invention often comprise the usual minor components in the field of the present invention in the usual quantity (approx. 5 wt.% to 15 wt.% minor components).

[0099] In some cases, it is also preferred, particularly if the formation of CO2 in step S2) of the process according to the invention is not to be completely excluded, to produce or provide methane (natural gas) as a reducing gas in step S1) and to use it in step S2) to reduce the produced or provided alkaline earth metal sulfate to alkaline earth metal sulfide. In many cases, it is preferred to use mixtures of hydrogen and methane (natural gas). In many cases, the mixing ratios of hydrogen and methane (natural gas) are preferably selected such that the CO2 produced can be introduced in step S4) and the amount of alkaline earth metal sulfide resulting in step S2) of the process according to the invention is reacted with the amount of CO2 resulting in step S2) of the process according to the invention to form alkaline earth metal carbonate. In many cases, it is preferred in the process according to the invention to use natural gas as methane.

[0100] The advantages and effects associated with the method according to the invention are also advantageously realized here.

[0101] A preferred method (as described above, preferably referred to as preferred above) is one comprising the following additional step:

[0102] 55) Separating at least a proportion of the alkaline earth metal carbonate precipitated as a solid in step S4) to obtain a separated alkaline earth metal carbonate, wherein the separation preferably comprises centrifugation and / or filtration, preferably centrifugation; and optionally with the following additional step:

[0103] 56) Dry at least a portion of the separated alkaline earth metal carbonate resulting from step S5) to obtain a dried alkaline earth metal carbonate; and / or with the following additional step:

[0104] 57) Calcining the separated alkaline earth metal carbonate resulting from step S5) and / or the dried alkaline earth metal carbonate resulting from step S6) to produce a calcined alkaline earth metal carbonate; and / or with the following additional step between the preparation or provision in step S1) and the reduction in step S2):

[0105] S1 a) Heating the alkaline earth metal sulfate produced or provided in step S1), preferably heating to a temperature in the range of 400 °C to 1400 °C, preferably to a temperature in the range of 500 °C to 1300 °C, particularly preferably to a temperature in the range of 600 °C to 1100 °C, most preferably to a temperature in the range of 700 °C to 950 °C; and / or with the following additional step between the production or provision in step S1) and the reduction in step S2):

[0106] S1 b) of the reducing gas produced or provided in step S1), preferably heating to a temperature in the range of 400 °C to 1400 °C, preferably to a temperature in the range of 500 °C to 1300 °C, particularly preferably to a temperature in the range of 600 °C to 1100 °C, most preferably to a temperature in the range of 700 °C to 950 °C.

[0107] The fact that step S6) is an optional step means that in some cases the other steps of the method according to the invention are carried out without step S6); in other cases the other steps of the method according to the invention are carried out and step S6) is also carried out.

[0108] In many cases, when an alkaline earth metal carbonate is produced in the process according to the invention, it is preferred that the separated alkaline earth metal carbonate resulting from step S5) and / or the dried alkaline earth metal carbonate resulting from step S6) be calcined in an additional process step. In some cases, it is preferred that the separated alkaline earth metal carbonate resulting from step S5) be calcined alone. In other cases, it is preferred that the dried alkaline earth metal carbonate resulting from step S6) be calcined alone. In other cases, it is preferred that quantities of the separated alkaline earth metal carbonate resulting from step S5) and the dried alkaline earth metal carbonate resulting from step S6) are first combined and the resulting total quantity is then calcined together.The expert independently selects a suitable procedure based on the requirements of the individual case and on the basis of his general expertise.

[0109] In many cases, it is preferred that an additional process step is carried out between the production or provision in step S1) and the reduction in step S2), preferably in the same reactor in which the reduction is subsequently carried out, namely the step:

[0110] S1 a) Heating the alkaline earth metal sulfate produced or provided in step S1), preferably heating to a temperature in the range of 400 °C to 1400 °C, preferably to a temperature in the range of 500 °C to 1300 °C, particularly preferably to a temperature in the range of 600 °C to 1100 °C, most preferably to a temperature in the range of 700 °C to 950 °C.

[0111] In many cases, it is preferred that an additional process step is carried out between the production or provision in step S1) and the reduction in step S2), namely the step:

[0112] S1 b) of the reducing gas produced or provided in step S1), preferably heating to a temperature in the range of 400 °C to 1400 °C, preferably to a temperature in the range of 500 °C to 1300 °C, particularly preferably to a temperature in the range of 600 °C to 1100 °C, most preferably to a temperature in the range of 700 °C to 950 °C.

[0113] In many cases, step S1 b) is preferably carried out in the same reactor in which the subsequent reduction is also performed. In many other cases, step S1 b) is also carried out outside the reactor in which the subsequent reduction is also performed, and the heated reducing gas is then introduced into the reactor.

[0114] The advantages and effects associated with the method according to the invention are also advantageously realized here.

[0115] A preferred method is (as described above, preferably referred to as preferred as above), wherein

[0116] Step S2) of the procedure is carried out as a continuous process; or

[0117] Step S2) of the process is carried out as a batch process; and / or wherein the alkaline earth metal carbonate precipitated as a solid in step S4); and / or the separated alkaline earth metal carbonate resulting in step S5); and / or the dried alkaline earth metal carbonate resulting in step S6); is selected from the group consisting of:

[0118] Barium carbonate (BaCCh), preferably barium carbonate comprising less than 10 wt.% impurities, preferably less than 7 wt.%, particularly preferably less than 5 wt.%, most preferably less than 2 wt.%, in each case based on the total mass of barium carbonate and the included impurities; and / or less than 2 wt.% strontium oxide (SrO), preferably less than 1.8 wt.%, particularly preferably less than 1.6 wt.%, most preferably less than 1.45 wt.%, in each case based on the total mass of barium carbonate and the included impurities; and

[0119] Strontium carbonate (SrCOs), preferably strontium carbonate comprising less than 10 wt.% impurities, preferably less than 7 wt.%, particularly preferably less than 5 wt.%, most preferably less than 2 wt.%, in each case based on the total mass of strontium carbonate and the included impurities; and / or less than 2 wt.% barium oxide (BaO), preferably less than 1.8 wt.%, particularly preferably less than 1.6 wt.%, most preferably less than 1.45 wt.%, in each case based on the total mass of strontium carbonate and the included impurities; and / or wherein the hydrogen sulfide resulting in step S4) is separated from the gas phase and / or

[0120] - is further processed into sulfur dioxide and elemental sulfur; preferably in a Claus process; and / or

[0121] - is further processed into NaHS; and / or

[0122] - is used in a chemical process that does not have elemental sulfur as the target product and does not have NaHS as the target product.

[0123] The further processing of the hydrogen sulfide produced in step S4) of the process according to the invention into sulfur dioxide and elemental sulfur advantageously contributes in many cases to the improved environmental compatibility of step S4) of the process according to the invention, and preferably to the improved environmental compatibility of the process according to the invention as a whole. This is achieved in a particularly advantageous manner in many cases with the Claus process. The Claus process is known to those skilled in the art as a process for the industrial production of sulfur from hydrogen sulfide from their general technical knowledge.

[0124] The further processing of the hydrogen sulfide produced in step S4) of the process according to the invention to form NaHS in many cases advantageously contributes to the improved environmental compatibility of step S4) of the process according to the invention, and preferably to the improved environmental compatibility of the process according to the invention as a whole. The use of the hydrogen sulfide produced in step S4) of the process according to the invention in a chemical process that does not have elemental sulfur as a target product and does not have NaHS as a target product in many cases advantageously contributes to the improved environmental compatibility of step S4) of the process according to the invention, and preferably to the improved environmental compatibility of the process according to the invention as a whole.

[0125] The advantages and effects associated with the method according to the invention are also advantageously realized here.

[0126] A preferred method (as described above, preferably referred to as preferred above) is wherein step S2) of the method is carried out wholly or partly, preferably wholly, in a rotary kiln, and wherein the alkaline earth metal sulfate has a temperature in the range of 400 °C to 1400 °C when produced or provided in step S1), preferably a temperature in the range of 500 °C to 1300 °C, particularly preferably a temperature in the range of 600 °C to 1100 °C, and most preferably a temperature in the range of 700 °C to 950 °C; and / or wherein the reducing gas has a temperature in the range of 400 °C to 1400 °C when manufactured or provided in step S1), preferably a temperature in the range of 500 °C to 1300 °C, particularly preferably a temperature in the range of 600 °C to 1100 °C, most preferably a temperature in the range of 700 °C to 1050 °C;and / or wherein the temperature during the process is in the range of 400 °C to 1400 °C, preferably in the range of 500 °C to 1200 °C, particularly preferably in the range of 600 °C to 1000 °C, and most preferably in the range of 700 °C to 950 °C; and / or wherein step S2) is carried out at a pressure in the range of 0.5 bar to 1.5 bar, preferably at a pressure in the range of 0.7 bar to 1.3 bar, particularly preferably at a pressure in the range of 0.8 bar to 1.2 bar, and most preferably at a pressure in the range of 0.8 bar to 1.1 bar; preferably at a pressure in the range of 0.9 bar to 0.99 bar; and / or wherein in step S2) solids and reducing gas pass through the rotary kiln in countercurrent flow;and / or wherein, for heating the rotary kiln, reducing gas, preferably methane gas, is preheated to a temperature in the range of 500°C to 1300°C, preferably in the range of 600°C to 1100°C, particularly preferably in the range of 700°C to 1050°C in a preheater, preferably an electric preheater, before entering the rotary kiln; and / or wherein, for heating the rotary kiln, oxygen is additionally supplied to the rotary kiln so that a portion of the reducing gas introduced into the rotary kiln reacts in an exothermic reaction with oxygen in the rotary kiln; and / or wherein the rotary kiln is electrically heated; and / or wherein the gas mixture exiting the rotary kiln has a higher temperature than the solids entering the rotary kiln;and / or, preferably “and”, wherein the gas mixture exiting the rotary kiln is wholly or partially processed after exiting the rotary kiln, resulting in a processed gas mixture, and wherein the processing preferably comprises the removal of particulate substances; and / or, preferably “and”, the processing comprises the removal of water; and / or, preferably “and”, the processing comprises the removal of carbon dioxide (CO2); and / or, preferably “and”.

[0127] Parts of the processed gas mixture are fed into the process as part of the reducing gas; and / or, preferably, the particulate substances separated during the separation of particulate substances are fed into the process as part of the alkaline earth metal sulfate; and / or wherein the gas mixture exiting the rotary kiln is used wholly or partly for heat recovery after exiting the rotary kiln.

[0128] In many cases, it is preferred that the process according to the invention be carried out in a rotary kiln. Taking into account, in particular, the mechanical and chemical properties of the reactants and products, the person skilled in the art can identify these cases independently, based on their general technical knowledge.

[0129] In many cases, particularly advantageous results are obtained when carrying out the inventive method in a rotary kiln using the temperature ranges defined above.

[0130] The pressure ranges defined above often yield particularly advantageous results when carrying out the process according to the invention in a rotary kiln. In many cases, it is preferable to operate the rotary kiln at a lower pressure than the surrounding environment, as this results in advantageously low dust generation; moreover, this often prevents undesirable and / or uncontrolled escape of reaction gases.

[0131] The fact that in step S2) the solids and reducing gas pass through the rotary kiln in countercurrent flow means that the flow directions of alkaline earth metal compounds (solids) and reducing gas in the rotary kiln are essentially opposite, preferably opposite.

[0132] The additional supply of oxygen to the rotary kiln for heating purposes, so that a portion of the reducing gas introduced into the rotary kiln reacts with oxygen in an exothermic reaction, is particularly preferred in many cases when methane (natural gas) or a mixture of methane (natural gas) and hydrogen is used as the reducing gas.

[0133] The exothermic reaction of the reducing gas with oxygen is preferably a combustion of the reducing gas.

[0134] In many cases, even when using pure hydrogen as the reducing gas, it is preferred to additionally supply oxygen to the rotary kiln for heating, so that a portion of the reducing gas introduced into the rotary kiln reacts exothermically with oxygen. When using high proportions of hydrogen in the reducing gas, those skilled in the art will exercise particular caution in the metering of hydrogen and oxygen for safety reasons. The use of suitable technical solutions is known to those skilled in the art.

[0135] To avoid heating large quantities of inert nitrogen, the use of pure oxygen is preferred in many cases; pure oxygen can be produced via various air separation processes. However, in some other cases, it is preferable to use air as an alternative means of introducing oxygen for reasons of process control requiring less equipment. The associated heating of the inert nitrogen contained in the air is accepted in these cases.

[0136] In many cases, it is preferred that the rotary kiln be electrically heated when carrying out the process according to the invention. In these cases, the supply of oxygen / air is preferably omitted. Electrical heating is frequently preferred in cases where a gas with a high hydrogen content is used as the reducing gas in order to increase the overall process reliability. However, electrical heating is also advantageous and therefore preferred in some other cases.

[0137] In many cases, the gas mixture exiting the rotary kiln has a higher temperature than the solids entering the kiln, because the exiting gas mixture was exposed to the reaction temperature inside the kiln before exiting. In these cases, the gas mixture exiting the rotary kiln particularly and preferably also has a higher temperature than the alkaline earth metal sulfate entering the kiln.

[0138] In many cases, a method according to the invention is preferred, wherein step S2) of the method is carried out wholly or partially, preferably entirely, in a rotary kiln, and wherein the gas mixture exiting the rotary kiln is wholly or partially processed after exiting the rotary kiln, resulting in a processed gas mixture, and wherein the processing preferably comprises the removal of particulate substances; in these cases, the removal of the particulate substances (comprising aerosol particles) is preferably carried out by means of a filter, particularly preferably by means of a cyclone separator. A cyclone separator is understood to be a filter within the scope of the present invention. In this way, the method is carried out with particularly high energy efficiency, without undesirable contamination in heat exchangers, purification devices, and / or pipelines.

[0139] In many cases, a process according to the invention is preferred, wherein step S2) of the process is carried out wholly or partially, preferably entirely, in a rotary kiln, and wherein the gas mixture exiting the rotary kiln is wholly or partially processed after exiting the rotary kiln, resulting in a processed gas mixture, and wherein portions of the processed gas mixture are recycled back into the process as part of the reducing gas; since even the smallest impurities would accumulate in the cycle if the processed residual gas were completely recycled, a certain amount of so-called purge gas must always be removed from the cycle. This high-calorific gas is preferably used in the process according to the invention for preheating reactants.

[0140] The inventive method, wherein step S2) of the method is carried out wholly or partially, preferably entirely, in a rotary kiln, and wherein the gas mixture exiting the rotary kiln is wholly or partially processed after exiting the rotary kiln, resulting in a processed gas mixture, and wherein the processing preferably includes the removal of carbon dioxide (CO2), is particularly preferred when methane (natural gas) or a mixture with a high proportion of methane (natural gas) is used as the reducing gas. In many cases, it is preferred to recirculate the reducing gas. In the case of CO2 removal, the gas mixture exiting the rotary kiln is recirculated after the CO2 removal (and after the removal of any other substances, if applicable).

[0141] In many cases, a process according to the invention is preferred, wherein step S2) of the process is carried out wholly or partially, preferably entirely, in a rotary kiln, and wherein the gas mixture exiting the rotary kiln is used wholly or partially for heat recovery after exiting the rotary kiln. In many cases, this means that the thermal energy of the exiting gas mixture is used directly or indirectly to preheat the reducing gas and / or the alkaline earth metal sulfate produced or provided in step S1). In this way, the process is carried out with particularly advantageously high energy efficiency. In many other cases, this means that the thermal energy of the exiting gas mixture is used directly or indirectly to generate steam. In this way, too, the process is carried out with particularly advantageously high energy efficiency.The advantages and effects associated with the method according to the invention are also advantageously realized here.

[0142] A preferred method (as described above, preferably referred to as preferred above) is wherein step S2) of the method is carried out wholly or partly, preferably entirely, in a shaft furnace, wherein the alkaline earth metal sulfate has a temperature in the range of 400 °C to 1400 °C when produced or provided in step S1), preferably a temperature in the range of 500 °C to 1300 °C, particularly preferably a temperature in the range of 600 °C to 1100 °C, and most preferably a temperature in the range of 700 °C to 950 °C; and / or wherein the reducing gas has a temperature in the range of 400 °C to 1400 °C when manufactured or provided in step S1), preferably a temperature in the range of 500 °C to 1300 °C, particularly preferably a temperature in the range of 600 °C to 1100 °C, most preferably a temperature in the range of 700 °C to 1050 °C;and / or wherein step S2) is carried out at a pressure of 0.8 bar to 15 bar, preferably at a pressure of 3 bar to 10 bar, particularly preferably at a pressure of 4 bar to 8.5 bar, most preferably at a pressure of 6.5 bar to 7.8 bar; and / or wherein the height of the solid bed in the shaft furnace is in the range of 1 m to 30 m, preferably in the range of 2 m to 20 m, particularly preferably in the range of 6 to 15 m, most preferably in the range of 8 m to 12 m; and / or wherein in step S2) during reduction the bulk density of the solid in the shaft furnace is in the range of 0.6 t / m³; 3 up to 3.2 t / m 3 is preferably in the range of 0.9 t / m 3 up to 2.9 t / m 3 , particularly preferably in the range of 1.3 t / m 3 up to 2.7 t / m 3 , especially preferred in the range of 1.5 kg / m² 3 up to 2.6 kg / m² 3, each based on the mean bulk density of the entire solid bed; and / or wherein the temperature during the process is in the range of 400 °C to 1400 °C, preferably in the range of 500 °C to 1200 °C, particularly preferably in the range of 600 °C to 1000 °C, most preferably in the range of 700 °C to 950 °C; and / or, preferably, wherein the alkaline earth metal sulfide resulting in step S2) leaves the shaft furnace at a temperature of less than 410 °C, preferably less than 400 °C, particularly preferably less than 390 °C, most preferably less than 385 °C; and / or wherein in step S2) solids and reducing gas pass through the shaft furnace in countercurrent flow; and / or wherein in step S2) the solids transport is gravity-driven;and / or wherein, for cooling the shaft furnace, reducing gas at a temperature of less than 40 °C, preferably less than 35 °C, particularly preferably less than 30 °C, and most preferably less than 25 °C, is introduced into the lower part of the shaft furnace for cooling; and / or wherein, for heating the shaft furnace, reducing gas, preferably methane gas, is preheated to a temperature in the range of 500 °C to 1300 °C, preferably 600 °C to 1100 °C, particularly preferably 700 °C to 1050 °C, in a preheater, preferably an electric preheater, before entering the shaft furnace; and / or wherein, for heating the shaft furnace, oxygen is additionally supplied to the shaft furnace so that a portion of the reducing gas introduced into the shaft tube furnace reacts in an exothermic reaction with oxygen in the shaft tube furnace; and / or wherein the shaft furnace is electrically heated;and / or wherein the gas mixture exiting the shaft furnace has a higher temperature than the solids entering the shaft furnace; and / or wherein the gas mixture exiting the shaft furnace is wholly or partially processed after exiting the shaft furnace, resulting in a processed gas mixture, and wherein the processing preferably comprises the removal of particulate substances; and / or the processing comprises the removal of water; and / or the processing comprises the removal of carbon dioxide (CO2); and / or;

[0143] Parts of the processed gas mixture are fed into the process as part of the reducing gas; and / or the particulate substances separated during the separation of particulate substances are fed into the process as part of the alkaline earth metal sulfate; and / or the gas mixture exiting the shaft furnace is used wholly or partly for heat recovery after exiting the shaft furnace.

[0144] In many cases, it is preferred that the process according to the invention be carried out in a shaft furnace. Taking into account, in particular, the mechanical and chemical properties of the reactants and products, the person skilled in the art can identify these cases independently, based on their general technical knowledge.

[0145] In many cases, particularly advantageous results are obtained when carrying out the inventive method in the shaft furnace using the temperature ranges defined above.

[0146] In many cases, the pressure ranges defined above yield particularly advantageous results when carrying out the inventive method in the shaft furnace.

[0147] With a solid bed height in the shaft furnace in the areas defined above, particularly advantageous results are often obtained when carrying out the process according to the invention in the shaft furnace. The process according to the invention is thus carried out particularly efficiently.

[0148] With a bulk density of the solid in the shaft furnace during reduction in step S2) in the ranges defined above, particularly advantageous results are obtained in many cases when carrying out the process according to the invention in the shaft furnace. The bulk density in the specified ranges ensures, in the process according to the invention, an advantageous combination of, on the one hand, a favorablely good flow of reducing gas and gaseous reaction products through the solid bed, and, on the other hand, a sufficiently large height of the solid bed for a sufficiently high material conversion during the process according to the invention.

[0149] The fact that in step S2) the solids and reducing gas pass through the shaft furnace in countercurrent flow means that the flow directions of alkaline earth metal compounds (solids) and reducing gas in the shaft furnace are essentially opposite, preferably opposite.

[0150] Supplying additional oxygen to the shaft furnace to heat it, so that a portion of the reducing gas introduced into the shaft furnace reacts exothermically with oxygen, is particularly preferred in many cases when methane (natural gas) or a mixture of methane (natural gas) and hydrogen is used as the reducing gas. The exothermic reaction of the reducing gas with oxygen is preferably a combustion of the reducing gas.

[0151] In many cases, even when using pure hydrogen as the reducing gas, it is preferred to additionally supply oxygen to the shaft furnace for heating, so that a portion of the reducing gas introduced into the shaft furnace reacts with oxygen in an exothermic reaction. When using high proportions of hydrogen in the reducing gas, those skilled in the art will exercise particular caution in the metering of hydrogen and oxygen for safety reasons. The use of suitable technical solutions is known to those skilled in the art.

[0152] To avoid heating large quantities of inert nitrogen, the use of pure oxygen is preferred in many cases; pure oxygen can be produced via various air separation processes. However, in some other cases, it is preferable to use air as an alternative means of introducing oxygen for reasons of process control requiring less equipment. The associated heating of the inert nitrogen contained in the air is accepted in these cases.

[0153] In many cases, it is preferred that the shaft furnace be electrically heated when carrying out the process according to the invention. In these cases, the supply of oxygen / air is preferably omitted. Electrical heating is frequently preferred in cases where a gas with a high hydrogen content is used as the reducing gas in order to increase the overall process reliability. However, electrical heating is also advantageous and therefore preferred in some other cases.

[0154] In many cases, the gas mixture exiting the shaft furnace has a higher temperature than the solids entering the shaft furnace, since the exiting gas mixture was exposed to the reaction temperature inside the shaft furnace before exiting. In these cases, the gas mixture exiting the shaft furnace particularly and preferably also has a higher temperature than the alkaline earth metal sulfate entering the shaft furnace.

[0155] In many cases, a method according to the invention is preferred, wherein step S2) of the method is carried out wholly or partially, preferably entirely, in a shaft furnace, and wherein the gas mixture exiting the shaft furnace is wholly or partially processed after exiting the shaft furnace, resulting in a processed gas mixture, and wherein the processing preferably comprises the removal of particulate substances; in these cases, the removal of the particulate substances (comprising aerosol particles) is preferably carried out by means of a filter, particularly preferably by means of a cyclone separator. In this way, the method is carried out with particularly high energy efficiency, without undesirable contamination in heat exchangers, purification devices and / or in pipelines.

[0156] In many cases, a method according to the invention is preferred, wherein step S2) of the method is carried out wholly or partly, preferably entirely, in a shaft furnace, and wherein in step S2) the solids transport is gravity-driven. In this way, the method in the shaft furnace is carried out in many cases with the use of particularly little energy, since energy expenditure to ensure the material transport in the shaft furnace is eliminated.

[0157] In many cases, a process according to the invention is preferred, wherein step S2) of the process is carried out wholly or partly, preferably entirely, in a shaft furnace, and wherein, for cooling the shaft furnace, reducing gas at a temperature of less than 40 °C, preferably less than 35 °C, particularly preferably less than 30 °C, and most preferably less than 25 °C, is introduced into the lower part of the shaft furnace. Introducing the gas into the lower part of the shaft furnace serves to cool the exiting solid reaction products (alkaline earth metal sulfides) and simultaneously heats the incoming reducing gas.

[0158] In many cases, a process according to the invention is preferred, wherein step S2) of the process is carried out wholly or partially, preferably entirely, in a shaft furnace, and wherein the gas mixture exiting the shaft furnace is wholly or partially processed after exiting the shaft furnace, resulting in a processed gas mixture, and wherein portions of the processed gas mixture are fed into the process as part of the reducing gas; since even the smallest impurities would accumulate in the cycle if the processed residual gas were completely recirculated, a certain amount of so-called purge gas must always be removed from the cycle. This high-calorific gas is preferably used in the process according to the invention for preheating reactants.

[0159] The inventive method, wherein step S2) of the method is carried out wholly or partially, preferably entirely, in a shaft furnace, and wherein the gas mixture exiting the shaft furnace is wholly or partially processed after exiting the shaft furnace, resulting in a processed gas mixture, and wherein the processing preferably includes the removal of carbon dioxide (CO2), is particularly preferred when methane (natural gas) or a mixture with a high proportion of methane (natural gas) is used as the reducing gas. In many cases, it is preferred to recirculate the reducing gas. In the case of CO2 removal, the gas mixture exiting the shaft furnace is recirculated after the removal of CO2 (and after the removal of any other substances, if applicable).

[0160] In many cases, a process according to the invention is preferred, wherein step S2) of the process is carried out wholly or partially, preferably entirely, in a shaft furnace, and wherein the gas mixture exiting the shaft furnace is used wholly or partially for heat recovery after exiting the shaft furnace. In many cases, this means that the thermal energy of the exiting gas mixture is used directly or indirectly to preheat the reducing gas and / or the alkaline earth metal sulfate produced or provided in step S1). In this way, the process is carried out with particularly advantageously high energy efficiency. In many other cases, this also means that the thermal energy of the exiting gas mixture is used directly or indirectly to generate steam. Here, too, the process is carried out with particularly advantageously high energy efficiency.

[0161] The advantages and effects associated with the method according to the invention are also advantageously realized here.

[0162] A preferred method is (as described above, preferably as referred to above as preferred) wherein celestine is provided wholly or partly as the alkaline earth metal sulfate in step S1); or wherein barite is provided wholly or partly as the alkaline earth metal sulfate in step S1); and / or wherein the alkaline earth metal sulfate in step S1) is produced or provided as a bulk material, preferably as a powdered bulk material and / or as a granulated bulk material.

[0163] In many cases, the product of the process according to the invention is an alkaline earth metal compound or a strontium compound. In these cases, it is often preferred that celestine (including the minor constituents typically present in celestine) is provided wholly or partially as the alkaline earth metal sulfate in step S1).

[0164] In this way, strontium compounds (excluding strontium sulfate) as alkaline earth metal compounds that are not alkaline earth metal sulfates are readily obtainable from sufficiently available starting materials (celestine) in the inventive process for the industrial production of alkaline earth metal compounds that are not alkaline earth metal sulfates.

[0165] The fact that celestine is provided in whole or in part in step S1) means that either celestine is provided as the sole alkaline earth metal sulfate in step S1) or that celestine is provided together with other strontium sulfates (e.g., strontium sulfates produced in a targeted chemical process) in step S1).

[0166] In many cases, the product of the process according to the invention is an alkaline earth metal compound, a barium compound. In these cases, it is often preferred that the alkaline earth metal sulfate provided in step S1) is wholly or partially barite (including the minor constituents typically present in barite). Barite is also known to those skilled in the art as baryte.

[0167] In this way, barium compounds (excluding barium sulfate) as alkaline earth metal compounds that are not alkaline earth metal sulfates are easily obtainable from sufficiently available starting materials (barite / barite) in the inventive process for the industrial production of alkaline earth metal compounds that are not alkaline earth metal sulfates.

[0168] The fact that barite (barytes) is provided wholly or partially in step S1) means that either barite is provided as the sole alkaline earth metal sulfate in step S1) or that barite is provided together with other barium sulfates (e.g., barium sulfates produced in a targeted chemical process). The advantages and effects associated with the process according to the invention are also advantageously realized here.

[0169] The invention further relates to a production plant for the manufacture of an alkaline earth metal compound that is not an alkaline earth metal sulfate, preferably an alkaline earth metal carbonate, particularly preferably an alkaline earth metal carbonate selected from the group consisting of: barium carbonate and strontium carbonate, wherein the production plant comprises at least:

[0170] A) a device for producing or providing a reducing gas, preferably a reducing gas selected from the group consisting of: methane (CH4 / natural gas), hydrogen (H2) and ammonia (NH3);

[0171] B) a device for producing or providing an alkaline earth metal sulfate, preferably an alkaline earth metal sulfate selected from the group consisting of: barium sulfate and strontium sulfate;

[0172] C) a reactor for the reduction of an alkaline earth metal sulfate using a reducing gas.

[0173] The production plant according to the invention allows the process according to the invention to be carried out in a particularly advantageous manner. The advantages and effects described above in connection with the process according to the invention are realized in a particularly positive way with the production plant according to the invention.

[0174] A preferred production plant (as described above, preferably as referred to above as preferred) additionally comprises

[0175] D) a container for an aqueous solution comprising a dissolved alkaline earth metal sulfide, wherein the container is preferably connected to a device for supplying water; and / or, preferably “and”

[0176] E) a stirring device for an aqueous solution comprising a dissolved alkaline earth metal sulfide; and / or preferably “and

[0177] F) a device for introducing carbon dioxide into a container for an aqueous solution comprising a dissolved alkaline earth metal sulfide; and / or

[0178] G) a device for separating hydrogen sulfide, preferably a device for separating hydrogen sulfide comprising one or more containers in which the suspension containing the alkaline earth metal carbonate is passed through with gaseous carbon dioxide (“stripping”); and / or

[0179] H) A device for separating solids, preferably alkaline earth metal carbonates, particularly preferably alkaline earth metal carbonates selected from the group consisting of: barium carbonate and strontium carbonate, from an aqueous solution, wherein the device is preferably selected from the group consisting of: centrifugation apparatus and filtration apparatus; particularly preferably the device is a centrifugation apparatus; and / or

[0180] I) a device for drying solid alkaline earth metal carbonates; and / or

[0181] J) a device for calcining alkaline earth metal carbonates; and / or

[0182] K) a device for heating the reactor for the reduction of an alkaline earth metal sulfate by means of a reducing gas; and / or

[0183] L) a device for heating an alkaline earth metal sulfate, preferably an alkaline earth metal sulfate selected from the group consisting of: barium sulfate and strontium sulfate, to temperatures in the range of 400 °C to 1400 °C, preferably to temperatures in the range of 500 °C to 1300 °C, particularly preferably to a temperature in the range of 600 °C to 1100 °C, most preferably to a temperature in the range of 700 °C to 950 °C; and / or

[0184] M) a device for heating a reducing gas, in particular methane and / or hydrogen, preferably for heating to a temperature in the range of 400 °C to 1400 °C, particularly preferably for heating to a temperature in the range of 700 °C to 1300 °C, most preferably to a temperature in the range of 750 °C to 1200 °C, very preferably to a temperature in the range of 800 °C to 1050 °C; and / or

[0185] N) a device for drying an alkaline earth metal sulfate, preferably an alkaline earth metal sulfate selected from the group consisting of: barium sulfate and strontium sulfate.

[0186] In many cases, it is preferred that the production plant according to the invention comprises a heatable container for an aqueous solution comprising a dissolved alkaline earth metal sulfide, wherein the container is preferably connected to a device for supplying preheated water. With such a container, an aqueous solution comprising a dissolved alkaline earth metal sulfide can be produced by adding solid alkaline earth metal sulfide to the heatable container, in which preheated water is placed, preferably by the connected device for supplying water. Particularly preferably, the container is additionally equipped with a stirring device for an aqueous solution comprising a dissolved alkaline earth metal sulfide.The container is particularly preferred if it is additionally equipped with a device for the targeted withdrawal of an aqueous solution containing a dissolved alkaline earth metal sulfide, such as a tap, a valve or a pipe.

[0187] With a production plant according to the invention comprising a device for introducing carbon dioxide into a container for an aqueous solution comprising a dissolved alkaline earth metal sulfide, step S4) of the process according to the invention is carried out particularly advantageously in many cases.

[0188] In many cases, particularly when step S4) of the process according to the invention is carried out with the production plant, it is preferred that the production plant according to the invention comprises a device for separating hydrogen sulfide, preferably a device for separating hydrogen sulfide comprising one or more containers in which the suspension containing the alkaline earth metal carbonate is percolated with gaseous carbon dioxide. Stripping is preferably carried out with such a production plant in many cases.

[0189] In many cases, particularly when step S4) of the process according to the invention is carried out with the production plant, it is preferred that the production plant according to the invention comprises a device for separating solids, preferably alkaline earth metal carbonates, and more preferably alkaline earth metal carbonates selected from the group consisting of barium carbonate and strontium carbonate, from an aqueous solution. The device is preferably selected from the group consisting of a centrifugation unit and a filtration unit; a centrifugation unit is particularly preferred. In many cases, barium carbonate or strontium carbonate are target products of the process according to the invention and are produced in a particularly advantageous manner with a production plant according to the invention equipped in this way.

[0190] In many cases, particularly when step S4) of the process according to the invention is carried out with the production plant, it is preferred that the production plant according to the invention includes a device for drying solid alkaline earth metal carbonates. In many cases where the process according to the invention is carried out with the production plant according to the invention, it is desirable to dry the solid alkaline earth metal carbonate resulting from step S4) of the process according to the invention. In many cases, barium carbonate or strontium carbonate are target products of the process according to the invention and are produced particularly advantageously with a preferably low residual moisture content using a production plant according to the invention equipped in this way.

[0191] With a production plant according to the invention comprising a device for calcining alkaline earth metal carbonates, step S7) of the process according to the invention is carried out particularly advantageously in many cases.

[0192] A production plant according to the invention, comprising a device for heating (the reactor for the reduction of an alkaline earth metal sulfate) by means of a reducing gas, is preferred in many cases. In many cases, this eliminates the need for additional electrical heating of the reactor.

[0193] With a production plant according to the invention comprising a device for heating an alkaline earth metal sulfate, preferably an alkaline earth metal sulfate selected from the group consisting of: barium sulfate and strontium sulfate, to temperatures in the range of 400 °C to 1400 °C, preferably to temperatures in the range of 500 °C to 1300 °C, particularly preferably to a temperature in the range of 600 °C to 1100 °C, most preferably to a temperature in the range of 700 °C to 950 °C; when carrying out the process according to the invention, in particular step S1 a) is carried out in a particularly advantageously efficient manner and with particularly advantageous results.

[0194] With a production plant according to the invention comprising a device for heating a reducing gas, in particular methane and / or hydrogen, preferably for heating to a temperature in the range of 400 °C to 1400 °C, particularly preferably for heating to a temperature in the range of 700 °C to 1300 °C, most preferably to a temperature in the range of 750 °C to 1200 °C, and very preferably to a temperature in the range of 800 °C to 1050 °C; when carrying out the process according to the invention, in particular step S1 b) is carried out in a particularly advantageously efficient manner and with particularly advantageous results.

[0195] In some cases, it is preferred to dry the alkaline earth metal sulfate produced or provided in step S1) of the process according to the invention before it is reduced in step S2) of the process according to the invention. The person skilled in the art selects these cases independently based on the requirements of the individual case and based on their general knowledge. In these cases, the process according to the invention is carried out particularly advantageously and efficiently with particularly advantageous results on a production plant according to the invention comprising a device for drying an alkaline earth metal sulfate.

[0196] The advantages and effects described above in connection with the inventive method and / or the inventive production plant also apply here accordingly.

[0197] A preferred production plant (as described above, preferably referred to as preferred above) is selected, wherein reactor C) is used for the reduction of an alkaline earth metal sulfate.

[0198] - a shaft furnace is or

[0199] - is a rotary kiln; and / or wherein the reactor C) for the reduction of an alkaline earth metal sulfate is sealed in such a way that there are no unacceptable leaks of the reducing gas; and / or wherein the reactor C) for the reduction of an alkaline earth metal sulfate is a rotary kiln and is suitable for continuous operation; and / or wherein the reactor C) for the reduction of an alkaline earth metal sulfate is a shaft kiln and is suitable for quasi-continuous operation; and / or wherein the reactor C) for the reduction of an alkaline earth metal sulfate is suitable for operation, preferably continuous operation, at operating temperatures in the range of 400 °C to 1200 °C, preferably in the range of 500 °C to 1100 °C.

[0200] In many cases, a production plant according to the invention is preferred, wherein the reactor C) for the reduction of an alkaline earth metal sulfate is a shaft furnace. In these cases, it is often preferred that the reactor C) for the reduction of an alkaline earth metal sulfate is a shaft furnace suitable for quasi-continuous operation. In many cases, it is preferred that the reactor is a shaft furnace and is operated quasi-continuously in the process according to the invention. That a shaft furnace is suitable for quasi-continuous operation means that the reduction can take place continuously in the shaft furnace and that the reducing gases can also be continuously fed into the shaft furnace, but that the solids can only be fed into or removed from the shaft furnace at short intervals and not in a continuous flow.

[0201] In many cases, a production plant according to the invention is preferred, wherein the reactor C) for the reduction of an alkaline earth metal sulfate is a rotary kiln. In these cases, it is often preferred that the reactor C) for the reduction of an alkaline earth metal sulfate is a rotary kiln suitable for continuous operation. In many cases, it is preferred that the reactor is a rotary kiln and is operated continuously in the process according to the invention.

[0202] The advantages and effects described above in connection with the inventive method and / or the inventive production plant also apply here accordingly.

[0203] A preferred production plant (as described above, preferably referred to as preferred above) is wherein reactor C) for the reduction of an alkaline earth metal sulfate is equipped with: an inlet opening for bulk solids, wherein the inlet opening for bulk solids is preferably equipped with a device for measuring the temperature of the bulk solids entering the inlet opening; and / or wherein the production plant has a device upstream of the inlet opening for bulk solids for measuring the mass and / or volume of the bulk solids entering the inlet opening; and / or an outlet opening for bulk solids, wherein the outlet opening for bulk solids is preferably equipped with a device for measuring the temperature of the bulk solids exiting the outlet opening;and / or an inlet opening for reducing gas, wherein the inlet opening for reducing gas is preferably equipped with a device for measuring the temperature of the reducing gas entering the inlet opening; and / or wherein the production plant is equipped with a device for measuring the mass and / or volume of the reducing gas entering the reactor; and / or an outlet opening for gaseous reaction byproducts, wherein the outlet opening for gaseous reaction byproducts is preferably equipped with a device for measuring the temperature of the gaseous reaction byproducts exiting the outlet opening; and / or wherein the production plant is equipped with a device for measuring the mass and / or volume of the gaseous reaction byproducts exiting the outlet opening;and / or wherein the production plant is equipped with a device for measuring the concentration of substances in the gaseous reaction byproducts exiting the outlet opening.

[0204] In many cases, a production plant according to the invention is preferred, wherein the reactor C) for the reduction of an alkaline earth metal sulfate is equipped with an inlet opening for bulk solids, and wherein the temperature and / or mass and / or volume of the bulk solids entering the inlet opening are determined by means of a suitable device (sensor). In many cases, it is preferred to process the obtained data digitally and to use the data for controlling the production plant according to the invention and / or for optimizing the process according to the invention.

[0205] In many cases, a production plant according to the invention is preferred, wherein the reactor C) for the reduction of an alkaline earth metal sulfate is equipped with an outlet opening for bulk solids and wherein the temperature of the bulk solids exiting the outlet opening is determined by means of a suitable device (sensor). In many cases, it is preferred to process the obtained temperature data digitally and to use the temperature data for controlling the production plant according to the invention and / or for optimizing the process according to the invention.

[0206] In many cases, a production plant according to the invention is preferred, wherein the reactor C) for the reduction of an alkaline earth metal sulfate is equipped with an inlet opening for reducing gas, and wherein the temperature and / or mass and / or volume of the reducing gas entering the inlet opening are determined by means of a suitable device (sensor). In many cases, it is preferred to process the obtained data digitally and to use the data for controlling the production plant according to the invention and / or for optimizing the process according to the invention.

[0207] In many cases, a production plant according to the invention is preferred, wherein the reactor C) for the reduction of an alkaline earth metal sulfate is equipped with an outlet opening for gaseous reaction products, and wherein the temperature and / or mass and / or volume of the gaseous reaction products exiting the outlet opening are determined by means of a suitable device (sensor). In many cases, it is preferred to process the obtained data digitally and to use the data for controlling the production plant according to the invention and / or for optimizing the process according to the invention.

[0208] The term “gaseous reaction byproducts” is to be understood broadly in this context and includes not only the gaseous products that result from a reaction when carrying out the process according to the invention and that escape from the reactor, but also all escaping gaseous substances, for example inert gases (such as nitrogen, argon and others) as well as unreacted starting materials and gaseous byproducts that escape from the reactor in gaseous form.

[0209] The advantages and effects described above in connection with the inventive method and / or the inventive production plant also apply here accordingly.

[0210] A preferred production plant (as described above, preferably as referred to above as preferred) is wherein reactor C) for the reduction of an alkaline earth metal sulfate is a shaft furnace, and wherein the shaft furnace is suitable for operating temperatures in the range of 400 °C to 1400 °C, preferably in the range of 500 °C to 1200 °C, particularly preferably in the range of 600 °C to 1000 °C, and most preferably in the range of 700 °C to 950 °C; and / or wherein the shaft furnace is not equipped with devices for the active mechanical conveying of solids; and / or wherein the shaft furnace is designed such that the conveyance of bulk solids from an inlet opening for bulk solids to an outlet opening for bulk solids is carried out by gravity;and / or wherein the shaft furnace is equipped with an inlet opening for bulk solids and an inlet opening for reducing gas, wherein these inlet openings are arranged such that a countercurrent of bulk solids and reducing gases can be generated in the shaft furnace; and / or wherein the shaft furnace is designed such that the inlet opening for bulk solids is configured as a lock system with movable flaps; and / or wherein the shaft furnace is equipped with an outlet opening for bulk solids, which is configured as a lock system with movable flaps; and / or wherein the shaft furnace is equipped with a device for temperature monitoring with which the temperature of the bulk solids exiting through the outlet opening for bulk solids can be determined;and / or wherein the shaft furnace is equipped with a device for electrically heating the shaft furnace and the solids contained therein.;

[0211] The fact that the shaft furnace is not equipped with devices for the active mechanical transport of solids also means, in particular, that there are no conveyor belts, screw conveyors and agitators inside the shaft furnace, preferably no conveyor belts, screw conveyors, agitators and corresponding devices.

[0212] The process according to the invention is particularly advantageous in many cases when using a shaft furnace equipped with an inlet opening for bulk solids and an inlet opening for reducing gas, wherein these inlet openings are arranged such that a countercurrent of bulk solids and reducing gases can be generated in the shaft furnace. With such a shaft furnace, a particularly simple process control is often achieved when carrying out the process according to the invention. Furthermore, the countercurrent of the gas results in an advantageous transfer of thermal energy from the hot exiting gaseous reaction products to the incoming, often significantly colder, alkaline earth metal sulfate.

[0213] In one possible embodiment, material can be fed in by opening the first flap while the second flap remains closed. The first flap is then closed before the second flap is opened to allow the feedstock to fall into the shaft. This allows the addition of solid material to the reactor (shaft furnace) to occur quasi-continuously in many cases, while the addition of reducing gas to the reactor (shaft furnace) is preferably continuous in many cases.

[0214] With a production plant according to the invention, wherein reactor C) for the reduction of an alkaline earth metal sulfate is a shaft furnace, and wherein the shaft furnace is equipped with a device for electrically heating the shaft furnace and the solids contained therein, the process according to the invention is carried out particularly advantageously in many cases. In many other cases, however, it is preferable to dispense with a device for electrically heating the shaft furnace and the solids contained therein, since this results in a simplified design of the production plant according to the invention.

[0215] In many cases, however, it is also preferred that the process according to the invention is carried out with a production plant according to the invention, wherein the reactor C) for the reduction of an alkaline earth metal sulfate is a shaft furnace, and wherein the shaft furnace is equipped with a device for electrically heating the shaft furnace and the solids contained therein, and is electrically heated during the execution of the process according to the invention, and wherein, during the execution of the process according to the invention, the reactor (shaft furnace) is additionally heated by burning reducing gas. In this way, particularly advantageous temperature gradients are obtained in the reactor (shaft furnace) in many cases, with which the process according to the invention can be carried out with particularly advantageous results.

[0216] By using a device for electrically heating the shaft furnace and the solids contained therein, additional consumption of reducing gas (for example, by heating the reactor by burning reducing gas) is avoided.

[0217] A production plant with an externally heated shaft furnace (e.g., by a heating jacket) is often associated with an unfavorable radial temperature gradient and is therefore often not preferred as part of a production plant according to the invention. For the same reasons, external heating of the shaft furnace (reactor) is also often not preferred when carrying out the process according to the invention. The advantages and effects described above in connection with the process and / or the production plant according to the invention also apply accordingly here.

[0218] A preferred production plant (as described above, preferably as referred to above as preferred) is wherein reactor C) for the reduction of an alkaline earth metal sulfate is a rotary kiln, and wherein the rotary kiln is suitable for operating temperatures in the range of 400 °C to 1400 °C, preferably in the range of 500 °C to 1200 °C, particularly preferably in the range of 600 °C to 1000 °C, and most preferably in the range of 700 °C to 950 °C; and / or wherein the rotary kiln is equipped with devices for actively mixing solids and the gas phase; and / or wherein the rotary kiln is equipped with an inlet opening for bulk solids and an inlet opening for reducing gas, wherein these inlet openings are arranged such that a countercurrent of bulk solids and reducing gases can be generated in the rotary kiln;and / or wherein the production plant is designed such that a lock system, preferably a lock system with movable flaps, is located in front of the inlet opening for solids of the rotary kiln; and / or wherein the production plant is equipped with an outlet opening for bulk solids, which is designed as a lock system; and / or wherein the rotary kiln is equipped with a device for temperature monitoring with which the temperature of the bulk solids exiting through the outlet opening for bulk solids can be determined; and / or wherein the rotary kiln is equipped with a device for electrically heating the rotary kiln and the solids contained therein.

[0219] In many cases, it is preferred that the rotary kiln be equipped with devices for actively mixing the solids and the gas phase. The solids and gas phase are preferably mixed in such a way as to support the reduction reaction in the most advantageous manner. In many cases, it is preferred that the rotary kiln be internally equipped with suitable internal components that facilitate the transport of solids within the kiln during rotation. Such internal components are known to those skilled in the art.

[0220] The process according to the invention is particularly advantageous in many cases when using a rotary kiln equipped with an inlet opening for bulk solids and an inlet opening for reducing gas, wherein these inlet openings are arranged such that a countercurrent of bulk solids and reducing gases can be generated in the rotary kiln. With such a rotary kiln, a particularly simple process control is often achieved when carrying out the process according to the invention. Furthermore, the countercurrent of the gas results in an advantageous transfer of thermal energy from the hot exiting gaseous reaction products to the incoming, often significantly colder, alkaline earth metal sulfate.

[0221] The addition of solid material to the reactor (rotary kiln) is in many cases continuous; the addition of reducing gas to the reactor (rotary kiln) is also preferably continuous in many cases.

[0222] With a production plant according to the invention, wherein reactor C) for the reduction of an alkaline earth metal sulfate is a rotary kiln, and wherein the rotary kiln is equipped with a device for electrically heating the rotary kiln and the solids contained therein, the process according to the invention is carried out particularly advantageously in many cases. In many other cases, however, it is preferable to dispense with a device for electrically heating the rotary kiln and the solids contained therein, since this results in a simplified design of the production plant according to the invention.

[0223] In many cases, however, it is also preferred that the process according to the invention is carried out with a production plant according to the invention, wherein the reactor C) for the reduction of an alkaline earth metal sulfate is a rotary kiln, and wherein the rotary kiln is equipped with a device for electrically heating the rotary kiln and the solids contained therein, and is electrically heated when the process according to the invention is carried out, and wherein, when the process according to the invention is carried out, the reactor (rotary kiln) is additionally heated by burning reducing gas. In this way, particularly advantageous temperature gradients are obtained in the reactor (rotary kiln) in many cases, with which the process according to the invention can be carried out with particularly advantageous results.

[0224] When using a device for electrically heating the rotary kiln and the solids contained therein, additional consumption of reducing gas (for example, by heating the reactor through combustion of reducing gas) is avoided. The advantages and effects described above in connection with the process and / or the production plant according to the invention also apply accordingly here.

[0225] The invention further relates to the use of hydrogen and / or methane, preferably the use of hydrogen, in a process for producing an alkaline earth metal compound that is not an alkaline earth metal sulfate, preferably an alkaline earth metal carbonate, preferably an alkaline earth metal carbonate selected from the group consisting of: barium carbonate and strontium carbonate, wherein the process is preferably a process as described above, and particularly preferably a process as described above, which is referred to as preferred.

[0226] By using hydrogen and / or methane according to the invention to produce an alkaline earth metal compound that is not an alkaline earth metal sulfate (as described above, preferably referred to as preferred above), alkaline earth metal compounds that are not alkaline earth metal sulfates are produced in a particularly advantageous manner.

[0227] In many cases, the use of hydrogen according to the invention for the production of an alkaline earth metal compound that is not an alkaline earth metal sulfate (as described above, preferably as referred to above as preferred) is preferred because, in the use of hydrogen according to the invention, alkaline earth metal compounds that are not alkaline earth metal sulfates are produced without CO2 being generated in the necessary reactions. Such a use of hydrogen (without the use of additional reducing gases) is therefore particularly preferred.

[0228] The advantages and effects described above in connection with the inventive method and / or the inventive production plant also apply here accordingly.

[0229] The invention further relates to a kit for the production (preferably for industrial production) preferably for the production of alkaline earth metal carbonate, particularly preferably for the production of alkaline earth metal carbonate selected from the group consisting of: barium carbonate and strontium carbonate, at least comprising: a sulfate compound, preferably barium sulfate and / or strontium sulfate; and a reducing gas, preferably methane and / or hydrogen, particularly preferably hydrogen.

[0230] With the kit according to the invention, the method according to the invention is carried out in a particularly advantageous way in many cases.

[0231] The advantages and effects described above in connection with the inventive method and / or the inventive production plant and / or inventive uses also apply here accordingly.

[0232] The invention further relates to the use of a kit (as described above, preferably as referred to above as preferred) for the production of an alkaline earth metal compound which is not an alkaline earth metal sulfate, preferably for the production of an alkaline earth metal carbonate, particularly preferably for the production of an alkaline earth metal carbonate selected from the group consisting of: barium carbonate and strontium carbonate, wherein the process is preferably a process as described above, particularly preferably a process as referred to above as preferred.

[0233] The use of the kit according to the invention allows the advantages of the kit to be realized in a particularly advantageous way.

[0234] The advantages and effects described above in connection with the inventive method and / or the inventive production plant and / or inventive uses and / or the inventive kit also apply accordingly here. The present invention is described in more detail below with reference to the figures.

[0235] Fig. 1 shows a production plant (here a production plant comprising a rotary kiln) for the production of an alkaline earth metal compound that is not an alkaline earth metal sulfate and which is suitable for carrying out the process according to the invention for the industrial production of an alkaline earth metal compound that is not an alkaline earth metal sulfate. Fig. 1 shows a rotary kiln (101) which is connected via a connecting piece (102) to a downstream cooler (139).

[0236] A feed stream comprising BaSC (105) is transported via a conveyor belt (106) to a screw conveyor with a feed hopper and airlock system (107) located upstream of the solids inlet of the rotary kiln and enters the rotary kiln (101) via this conveyor. The solids stream (137) carries the solids through the rotary kiln, where reduction takes place, and then through the connecting piece (102) and the downstream cooler (139), from which they exit via a screw conveyor with a feed hopper and airlock system (133) after the cooler's solids outlet. They are then transported further by a conveyor belt (134) until the output stream of solid reaction products comprising BaS (135) leaves the production plant.

[0237] A mass inlet stream of hydrogen for cooling (136) is introduced into the cooler (139) via a line (103), so that it cools the mass stream of solids (137) in the opposite direction.

[0238] Gaseous reaction byproducts leave the rotary kiln (101) and are conveyed via a line (110) into a cyclone separator (108), in which the gaseous reaction byproducts are freed from particulate substances.

[0239] The particulate substances separated in the cyclone separator (108) are fed back to the material input stream comprising BaSC (105) via a return (109) on the conveyor belt (106) and thus recycled in the process.

[0240] The gaseous reaction byproducts, freed from particulate matter in the cyclone separator (108), exit the cyclone separator (108) as a hot gas stream and are fed via a suitable line (115) to a heat exchanger (117). In the heat exchanger, the thermal energy of the hot gas stream from (115) is used to heat a mixture of hydrogen and recycled water from another line (116) for feeding into the rotary kiln. The cooled gaseous reaction byproducts exit the heat exchanger (117) and are fed via a suitable line (125) into a cooler (126), where the water present in the cooled gaseous reaction byproducts is removed by condensation. The condensed liquid water exits the production plant as the output stream (127).The cooled gaseous reaction products, dried in the cooler (126), are directed via a suitable line (129) to a splitting point (128) to separate the mass flow from line (129) into two partial streams (131 , 114).

[0241] One partial stream (131) from the dividing point (128) is combusted (reacted) in a burner (124) to react the hydrogen present in the material stream (131) with air (130), which is supplied via an air inlet stream (112). The hot combustion gases (123) exiting the burner (124) are directed into a heat exchanger (121), where their thermal energy heats a further preheated hydrogen-rich gas mixture entering the heat exchanger (121) via another line (120). The cooled combustion gases (122) leave the heat exchanger (121) and are discharged from the production plant as exhaust gas (140) (in many cases, this exhaust gas is preferably directed directly to an exhaust gas treatment plant – not shown here).

[0242] The other partial stream (114) from the dividing point (128) is mixed in a mixing point (113) with a hydrogen input stream (111), resulting in a hydrogen-rich gas mixture, and is fed into a heat exchanger (117) where it is heated by the thermal energy of the hot gas stream from (115). The resulting heated hydrogen-rich gas mixture is then conveyed via a suitable line (125) to an electric heater (119) for further preheating. The further preheated hydrogen-rich gas mixture exiting the electric heater (119) is then conveyed via another line (120) to the heat exchanger (121) where it is fully preheated by the thermal energy of the hot combustion gases (123) exiting the burner (124).The resulting preheated hydrogen-rich gas mixture is fed to the rotary kiln (101) via a suitable line (104) and flows through it as a (reduction) gas stream (138). Fig. 2 shows a production plant (here a production plant comprising a shaft kiln) for the production of an alkaline earth metal compound that is not an alkaline earth metal sulfate and which is suitable for carrying out the process according to the invention for the industrial production of an alkaline earth metal compound that is not an alkaline earth metal sulfate. Fig. 2 shows a shaft kiln (201).

[0243] A material input stream comprising SrSC (235) is transported via a conveyor belt (209) to a sluice system (208) in front of the solids inlet of the shaft furnace and enters the shaft furnace (201) via this.

[0244] The solid material flow (238) carries the solids through the shaft furnace, in which a reduction takes place, and exits at the bottom through a sluice system (203) after the shaft furnace's solids discharge opening. It is then transported further by a conveyor belt (204) until the discharge stream, comprising solid reaction products including SrS (234), leaves the production plant.

[0245] A mass inlet stream of methane for cooling (202) is introduced into the shaft furnace via a line (237), so that it cools the mass stream of solids (238) in the opposite direction.

[0246] Gaseous reaction byproducts leave the shaft furnace (201) and are conveyed via a suitable pipe into a cyclone separator (210), in which the gaseous reaction byproducts are freed from particulate substances.

[0247] The particulate substances separated in the cyclone separator (210) are fed back to the material input stream containing SrSC (235) via a return (239) on the conveyor belt (209) and thus recycled in the process.

[0248] The gaseous reaction byproducts, freed from particulate matter in the cyclone separator (210), exit the cyclone separator (210) as a hot gas stream and are fed via a suitable line (205) to a heat exchanger (216). In the heat exchanger, the thermal energy of the hot gas stream from (205) is used to heat a mixture of hydrogen for feeding into the rotary kiln with processed, recycled hydrogen from another line (215). The cooled gaseous reaction byproducts exit the heat exchanger (216) and are fed via a suitable line (217) into a cooler (229), where the water present in the cooled gaseous reaction byproducts is removed by condensation. The condensed liquid water exits the production plant as the output stream (231).

[0249] The cooled gaseous reaction products, dried in the cooler (229), are directed via a suitable line (230) to a splitting point (232) to separate the mass flow from line (230) into two partial streams (226, 233).

[0250] One partial stream (233) from the dividing point (232) is combusted (reacted) in a burner (224) to react the hydrogen present in the mass stream (233) with air (225), which is supplied via an air inlet stream (211). The hot combustion gases (223) exiting the burner (224) are directed into a heat exchanger (219), where their thermal energy heats a further preheated hydrogen-rich gas mixture entering the heat exchanger (219) via another line (218). The cooled combustion gases (222) leave the heat exchanger (219) and are discharged from the production plant as exhaust gas (220) (in many cases, this exhaust gas is preferably directed directly to an exhaust gas treatment plant – not shown here).

[0251] The other partial stream (226) from the dividing point (232) is fed to an amine scrubber (227). A first partial stream (228), rich in CO2, emerges from the amine scrubber (227); this partial stream is discharged from the production plant as exhaust gas (in many cases, this exhaust gas is preferably directed to an exhaust gas treatment plant – not shown here). A second partial stream (214), comprising hydrogen and CO, also emerges from the amine scrubber (227). This is conveyed via a suitable line to a mixing point (213) and mixed in the mixing point (213) with a methane input stream (212), resulting in a methane-rich gas mixture. The methane-rich gas mixture is then fed into a heat exchanger (216) and heated there by the thermal energy of the hot gas stream from (205).The resulting heated methane-rich gas mixture is fed via a suitable line (218) into the heat exchanger (219) for complete preheating, where it is fully preheated by the thermal energy of the hot combustion gases (223) exiting the burner (224). The resulting fully preheated methane-rich gas mixture is then fed via a suitable line (221) to the shaft furnace (201) in a suitable manner and flows through it as a (reduction) gas stream (236). The present invention is described in more detail below with reference to examples.

[0252] 1 - Reduction of BaSC in a rotary kiln

[0253] 14.5 t / h of barium sulfate (BaSC₄) in powdered form (free-flowing and bulk-filled) was provided as an example of an alkaline earth metal sulfate. The material had a particle diameter dso of 50 pm. The bulk density of the material was 1.58 kg / L and the residual moisture content was 6.8%. The barium sulfate was continuously fed into the process via a conveyor belt. Dosing into a gas-tight rotary kiln was achieved by a screw conveyor whose feed hopper was equipped with an airlock to prevent unwanted gas escape. The rotation and inclination of the rotary kiln were selected so that the free-flowing barium sulfate (powder) was conveyed through the kiln with an average residence time of 1.5 h.The barium sulfate was first preheated from ambient temperature (outside the rotary kiln) to reaction temperature by the gas exiting the kiln at 630 °C. It was then reduced to barium sulfide (BaS) in the rotary kiln with a conversion rate of 95% using hydrogen (as an example of a reducing gas). Downstream of the rotary kiln was a cooler in which the material was cooled to 350 °C by introducing a partial gas stream at ambient temperature. The resulting BaS-BaSO4 mixture was then conveyed away by a screw conveyor behind the rotary kiln outlet. At the screw conveyor outlet, the material falls through a further airlock onto another conveyor belt and exits the process stage.

[0254] Hydrogen was used as the reducing agent for the reduction process in the rotary kiln. A gas flow of 17,500 Nm³ was supplied to the reactor. 3The gas stream was supplied at a rate of 37 wt% per hour. This consisted of fresh hydrogen, with the remainder being recirculated hydrogen. The gas stream was split before being fed into the reactor. A portion of the fresh hydrogen was mixed with the recirculated stream and preheated in a counterflow heat exchanger by the gas exiting the rotary kiln. This gas stream was then heated to 910 °C in an electric heater and a hydrogen-fired burner before being directed through a lance into the reaction zone of the rotary kiln, which operated at atmospheric pressure. The second portion of the total hydrogen stream was passed over the solid material at the bottom of the rotary kiln, heating up while simultaneously cooling the solid material. Due to the endothermic reduction reaction and the heating of the counterflowing particles, the gas stream cooled to 630 °C by the time it exited the rotary kiln.The gas is then passed through a cyclone separator to remove any particles carried along with it. The gas is then cooled to approximately 180 °C in a counterflow heat exchanger against the incoming hydrogen and recirculation stream. In a cooler, the gas is further cooled to temperatures below 40 °C, during which the water, a reaction product, is removed. Ninety percent of the remaining purified hydrogen stream is recycled, mixed with the fresh hydrogen stream, and fed via the counterflow heat exchanger to the electric heater and the burner. The remaining 10 percent of the gas stream is removed from the recirculation cycle to remove impurities (e.g., nitrogen) and fed to the hydrogen burner. In the burner, the gas entering the rotary kiln is preheated to the required inlet temperature by reaction with air in a heat exchanger.The burner's exhaust gas was routed through an exhaust gas aftertreatment system before being released into the environment.

[0255] The process yielded "black ash," comprising barium sulfide (BaS) as the main product, as an example of an alkaline earth metal sulfide obtained in the process according to the invention. One hundred cubic grams of BaS per hour were obtained; the BaS obtained could then be purified and further processed.

[0256] Further experiments have shown that, following the procedure in this example, SrS can also be obtained advantageously from SrSÜ4.

[0257] Example 2 - Purification of “Black ash”

[0258] The product of the reduction process described in Example 1 above is a solid mixture (comprising BaS as the main product), which is referred to below as "black ash" to describe the subsequent processing steps and processes.

[0259] The black ash was obtained as a fine powder from the reduction process in the rotary kiln. In the subsequent processing step, the BaS contained in the black ash was extracted with water in the leaching process. For this purpose, the powder (black ash) was stirred in dissolving agitators with rapidly rotating propeller-like tools in water at approximately 60 °C to 80 °C, during which, among other things, the following dissolution reaction took place:

[0260] BaS + H₂O → Ba(OH)(HS) The product of the dissolution process is a suspension containing approximately 13 wt% to 18 wt% dissolved BaS and additional insoluble components. The suspension, heated to 60 °C to 80 °C, is passed into thickeners. Here, the insoluble components of the black ash are separated from the dissolved BaS by sedimentation. The BaS solution obtained after separation of the insoluble components is then suitable for further processing into various barium products.

[0261] Example 3 - Production of barium carbonate (BaCO3) from a BaS solution by introducing CO2

[0262] A BaS solution prepared according to Example 2 above was further processed to BaCO3. For this purpose, gaseous CO2 was injected into the BaS solution, causing BaCO3 to precipitate out of the solution as a solid. During this reaction, carried out in gas-tight vessels, gaseous H2S was formed as a coproduct according to the reaction:

[0263] Ba(OH)(HS) + CO2BaCO3 + H2S

[0264] The obtained BaCO3 was partially separated from the water by filtration, leaving behind a mixture referred to as "dough" consisting of 65 wt.% to 85 wt.% solid and 15 wt.% to 35 wt.% water. This "dough" was then dried in a turbine dryer, resulting in a fine-grained BaCO3 powder (exemplary of an alkaline earth metal carbonate).

[0265] In alternative experiments conducted by the company itself, the “dough” was granulated in granulation drums, resulting in a coarse-grained BaCO3 granulate (exemplary of an alkaline earth metal carbonate).

[0266] The resulting H₂S gas was further processed in a Claus plant. The Claus process step results in the formation of elemental sulfur from the H₂S gas according to the following reaction equations:

[0267] 2 H2S + 3 O2 ⇌ SO2 + 2 H2O

[0268] 2 H2S + SO23 S + 2 H2O from a base el urch relocating with

[0269] As an alternative to producing BaCO3 by introducing CO2 into a BaS solution (see Example 3 above), BaCO3 was produced in Example 4 by adding a 30 wt% aqueous soda solution to a BaS solution prepared according to Example 2 above. BaCO3 precipitated as a solid. The reaction proceeds in suitable containers according to the following reaction equation:

[0270] Ba(OH)(HS) + Na2CO3BaCO3+ Na2S + H2O

[0271] The precipitation reaction was carried out with constant stirring to thoroughly mix both solutions (BaS solution and soda solution). The resulting BaCO3 was separated by filtration, yielding a paste with a solid content of 65% to 85% by weight and a liquid phase of 15% to 35% by weight. This paste was then washed by repeated resuspension in water and filtration, resulting in a BaCG3 product with a Na2S content of less than 0.2% by weight.

[0272] The final processing step to produce fine-grained BaCO3 powder or BaCO3 granules was carried out by drying in a turbine dryer or granulation in suitable granulating drums.

[0273] Example 5 - Preparation of Blanc fixe from a BaS solution using hydrochloric acid and sodium sulfate

[0274] In the present example 5, BaSO4 Blanc fixe was produced from a BaS solution prepared according to example 2 above.

[0275] For this purpose, a BaS solution prepared according to the above example 2 was first mixed with technical concentrated hydrochloric acid (approx. 35 wt%), resulting in a BaCl2 solution (approx. 10 wt% to 15 wt%) and gaseous H2S, as shown in the following reaction equation:

[0276] BaS + 2 HCl BaCI2+ H2S The reaction took place in gas-tight vessels and the resulting H2S was further processed to elemental sulfur in a Claus process analogous to the procedure described in example 3 above.

[0277] The addition of an aqueous solution of Na2SU4 (approx. 10 wt%) to the BaCl solution prepared in Example 5 resulted in the precipitation of BaSC (so-called “Blanc fixe”), according to the reaction equation:

[0278] BaCl + Na2SU4 BaSO4 + 2 NaCl

[0279] The BaSC contained in the suspension resulting from this precipitation was separated from the solution by filtration, and the resulting dough was washed several times with water until the desired NaCl content was reached.

[0280] Example 6 - Preparation of Blanc fixe from a BaS solution using sulfuric acid In the present example 6, BaSO4 Blanc fixe was prepared from a BaS solution prepared according to the above example 2.

[0281] For this purpose, a BaS solution prepared according to Example 2 above was mixed with technical-grade sulfuric acid (approx. 95 wt%). This also resulted in the precipitation of blanc fixe; this was processed according to the procedure described in Example 5 above.

[0282] Furthermore, gaseous H2S is formed. Therefore, the reaction also took place in gas-tight vessels, and the resulting H2S was further processed into elemental sulfur in a Claus process, analogous to the procedure described in Example 3 above.

[0283] Example 7 - Reduction of SrSO4 in a shaft furnace

[0284] At the top of a shaft furnace, pelletized strontium sulfate (SrSO4) (as an example of an alkaline earth metal sulfate) was fed semi-continuously via a sluice gate at an average throughput of 16.2 t / h. At the bottom of the shaft furnace, material was withdrawn from the 10 m high shaft at a rate of 10.8 t / h, resulting in an average residence time of 1.5 h for the material to be reduced. A reducing gas flowed through the shaft furnace in the opposite upward direction. This reducing gas was introduced at a temperature of 930 °C and a volumetric flow rate of 24,400 Nm³ at approximately one-third of the height of the shaft furnace. 3The reducing gas was a mixture of gases produced by combining a natural gas stream supplied to the process with a recirculating stream. On its way to the upper gas outlet of the furnace, the reducing gas was cooled to 650 °C at the furnace outlet by the endothermic reduction reaction occurring at 900 °C and by preheating the downward-moving fixed bed. The solid stream exiting the bottom of the furnace consisted of 95% SrS and 5% unreduced SrSÜ4 or other products from side reactions, in addition to the inert gangue in the raw material, and had a temperature of less than 400 °C at the furnace outlet. To achieve this temperature, ambient-temperature natural gas was introduced at the bottom of the furnace and also flowed upwards.The cold gas and the reforming reactions of the natural gas taking place in the bed achieved the necessary cooling of the solid to prevent reoxidation to sulfate after removal from the shaft furnace.

[0285] The recirculating gas stream, mixed with fresh natural gas, was heated in two counterflow heat exchangers before entering the shaft furnace. In the first heat exchanger, the heat from the shaft furnace exhaust gas was used for preheating after it had been cleaned of solid particles discharged from the furnace by a cyclone separator. During this process, the exhaust gas cooled to a temperature of approximately 200 °C. Post-treatment included a condensation stage for water removal, in which the gas stream was cooled to a temperature of approximately 40 °C. An amine scrubber was used to remove the CO2 produced. Subsequently, the remaining gas stream consisted largely of unused natural gas and contained only small amounts of water and CO2. To improve the utilization of the natural gas used, the gas stream was recirculated within the process stage.However, a partial stream separated before the amine scrubbing process had to be diverted to prevent the accumulation of impurities in the system; this partial stream was thermally converted in a burner with air. The heat released in this process was used in the second heat exchanger to set the desired shaft furnace inlet temperature of 930 °C, without requiring any additional electrical preheating.

[0286] The process yielded "white ash," comprising strontium sulfide (SrS) as the main product, as an example of an alkaline earth metal sulfide obtained in the process according to the invention. 10.8 t / h of product were obtained per hour; the SrS obtained could then be purified and further processed.

[0287] Further experiments have shown that BaS can also be obtained from BaSC in an advantageous way using the procedure in this example.

[0288] Example 8 - Purification of "White ash"

[0289] The product of the reduction process described in Example 7 above is a solid mixture (comprising SrS as the main product), which is referred to below as "white ash" to describe the subsequent processing steps and processes.

[0290] In the subsequent processing step, the SrS contained in the white ash was extracted with water in the leaching process. For this purpose, the white ash was stirred in dissolving agitators with rapidly rotating propeller-like tools in water at approximately 70 °C to 90 °C, during which, among other things, the following dissolution reaction took place:

[0291] SrS + H2O Sr(OH)(HS)

[0292] The product of the dissolution process is a suspension containing approximately 8 wt% to 12 wt% dissolved SrS and additional insoluble components. The suspension, heated to 70 °C to 90 °C, is passed into thickeners. Here, the insoluble components of the white ash are separated from the dissolved SrS by sedimentation. The resulting solid-free SrS solution, obtained after the removal of the insoluble components, is then suitable for further processing into various strontium products.

[0293] Example 9 - Production of strontium carbonate (SrCO3) from an SrS solution by introducing CO2

[0294] An SrS solution prepared according to Example 8 above was further processed to SrCO3. For this purpose, gaseous CO2 was injected into the SrS solution, causing the SrCO3 to precipitate out of the solution as a solid. During this reaction, carried out in gas-tight vessels, gaseous H2S is formed as a coproduct according to the following reaction:

[0295] Sr(OH)(HS) + CO₂ → SrCO₃ + H₂S The resulting SrCO₃ was partially separated from the water by filtration, leaving a mixture referred to as "dough" consisting of 65 wt.% to 85 wt.% solid and 15 wt.% to 35 wt.% water. This "dough" was then dried in a turbine dryer, resulting in a fine-grained SrCO₃ powder (exemplary of an alkaline earth metal carbonate).

[0296] In alternative experiments, the "dough" was granulated in granulating drums, resulting in coarse-grained SrCO3 granules (exemplary of an alkaline earth metal carbonate). The resulting H2S was further processed into elemental sulfur in a Claus process, analogous to the procedure described in Example 3 above.

[0297] Example 10 - Production of strontium carbonate (SrCO3) from an SrS solution by adding soda solution

[0298] As an alternative to the preparation of SrCO3 by introducing CO2 into an SrS solution (see Example 9 above), SrCO3 was prepared in Example 10 by adding a 30 wt% aqueous soda solution to an SrS solution prepared according to Example 8 above. As a result of this addition, SrCO3 precipitated as a solid. The reaction proceeds in suitable containers according to the following reaction equation:

[0299] Sr(OH)(HS) + Na2CO3SrCO3+ Na2S + H2O

[0300] The precipitation reaction was carried out with constant stirring to ensure thorough mixing of both solutions (SrS solution and soda solution). The resulting SrCO3 was separated by filtration, yielding a paste with a solid content of 65% to 85% by weight and a liquid phase of 15% to 35% by weight. This paste was then washed by repeated resuspension in water and filtration, resulting in an SrCG3 product with a Na2S content of less than 0.25% by weight.

[0301] The final processing step to produce fine-grained SrCO3 powder or SrCO3 granules was carried out by drying in a turbine dryer or granulation in suitable granulating drums. using hydrochloric acid

[0302] In the present example 11, SrCh was produced from an SrS solution prepared according to example 9 above.

[0303] For this purpose, an SrS solution prepared according to the above example 9 was first mixed with technical concentrated hydrochloric acid (approx. 35 wt%), resulting in an SrCl solution (approx. 6 wt% to 10 wt%) and gaseous H2S, as shown in the following reaction equation:

[0304] SrS + 2 HCl SrCl2+ H2S

[0305] The reaction took place in gas-tight vessels. Strontium chloride hexahydrate (SrCl₄I H₂O) was obtained as a crystal from the resulting SrCh solution by evaporating the water in dryers. The resulting H₂S was further processed to elemental sulfur in a Claus process, analogous to the procedure described in Example 3 above.

[0306] Example 12 - Production of strontium carbonate using hydrochloric acid and CO2

[0307] In the present example 12, SrCOs was produced from an SrS solution prepared according to example 9 above.

[0308] For this purpose, an SrS solution prepared according to the above example 9 was first mixed with technical concentrated hydrochloric acid (approx. 35 wt%), resulting in an SrCl solution (approx. 6 wt% to 10 wt%) and gaseous H2S, as shown in the following reaction equation:

[0309] SrS + 2 HCl SrCl2+ H2S

[0310] The reaction took place in gas-tight vessels. The resulting H₂S was further processed into elemental sulfur in a Claus process, analogous to the procedure described in Example 3 above.

[0311] The resulting SrCl solution was treated with sodium hydroxide solution (50 wt%), causing strontium hydroxide octahydrate (Sr(OH)₂ ■ 8 H₂O) to precipitate in crystalline form. The crystalline strontium hydroxide octahydrate (Sr(OH)₂ ■ 8 H₂O) was washed by repeated separation from the water using drum filters and subsequent resuspension to achieve a NaCl content of less than 0.007 wt%.

[0312] The purified strontium hydroxide was dissolved in water at approximately 60 °C to 80 °C, resulting in a solution containing approximately 10 wt% Sr(OH)₂. SrCO₃ was precipitated by injecting gaseous CO₂ into this Sr(OH)₂ solution.

[0313] The obtained SrCOs was partially separated from the water by filtration, leaving behind a mixture referred to as "dough" consisting of 65 wt.% to 85 wt.% solid and 15 wt.% to 35 wt.% water. This "dough" was then dried in a turbine dryer, resulting in a fine-grained SrCOs powder (exemplary of an alkaline earth metal carbonate).

[0314] In alternative experiments conducted by the company itself, the “dough” was granulated in granulation drums, resulting in a coarse-grained SrCOs granulate (exemplary of an alkaline earth metal carbonate).

Claims

Patent claims 1. A process for the industrial production of an alkaline earth metal compound other than an alkaline earth metal sulfate, comprising at least the following steps: 51) (i) Manufacture or supply of an alkaline earth metal sulfate and separately therefrom (ii) Production or supply of a reducing gas; 52) Reducing the alkaline earth metal sulfate produced or provided in step S1) using the reducing gas so that a corresponding alkaline earth metal sulfide results.

2. A method according to the preceding claim 1, wherein the alkaline earth metal compound which is not an alkaline earth metal sulfate is selected from the group consisting of: - Barium carbonate, - Barium soaps, - Barium sulfonates, - Barium titanate (BaTiCh), - Barium ferrite (BaFei2Oi9), - Barium chlorate (Ba(CIC>3)2), Barium chloride (BaCh) - Lithopone (BaSC ZnS), - Barium hydroxide (Ba(OH)2), - barium oxide (BaO), - Barium oxalate (BaC2C>4), - Barium acetate (Ba(C2H3C>2)2), - Barium chromate (BaCrC ), - other barium compounds, - Strontium carbonate, - strontium soaps, - strontium sulfonates, - Strontium titanate (SrTiOs), - Strontium ferrite (SrFei2Oi9), - Strontium chlorate (Sr(CIC>3)2), - Strontium chloride (SrCh), - Strontium hydroxide (Sr(OH)2), - Strontium oxide (SrO), - Strontium oxalate (SrC2C>4), Strontium acetate (Sr(C2H3C>2)2), Strontium chromate (SrCrC ), and - other strontium compounds.

3. The method according to the preceding claim 1, with the following additional step: 53) Producing an aqueous solution comprising dissolved components of the alkaline earth metal sulfide resulting in step S2), such that an aqueous solution comprising a dissolved alkaline earth metal sulfide results; and / or with the following additional step: 54) Introducing gaseous carbon dioxide into the aqueous solution resulting from step S3) comprising a dissolved alkaline earth metal sulfide, so that an alkaline earth metal carbonate results and precipitates wholly or partly as a solid; and so that hydrogen sulfide (H2S) results.

4. A method according to any one of the preceding claims, wherein the alkaline earth metal sulfate produced or provided in step S1) is selected from the group consisting of: Barium sulfate and Strontium sulfate; and / or wherein the reducing gas used in step S2) for the reduction of the alkaline earth metal sulfate is selected from the group consisting of: - Hydrogen (H2), - Ammonia (NH3), - Methane (CH4) and Mixtures thereof; and / or the alkaline earth metal sulfide resulting in step S2) is selected from the group consisting of: - Barium sulfide and - Strontium sulfide; and / or the alkaline earth metal carbonate resulting in step S4) is selected from the group consisting of: Barium carbonate (BaCCh) and Strontium carbonate (SrCCh).

5. Method according to any of the preceding claims with the following additional step: 55) Separating at least a proportion of the alkaline earth metal carbonate precipitated as a solid in step S4) to obtain a separated alkaline earth metal carbonate, wherein the separation preferably comprises centrifugation and / or filtration, preferably centrifugation; and optionally with the following additional step: 56) Drying at least a portion of the separated alkaline earth metal carbonate resulting from step S5) to obtain a dried alkaline earth metal carbonate; and / or with the following additional step: 57) Calcining the separated alkaline earth metal carbonate resulting from step S5) and / or of the dried alkaline earth metal carbonate resulting in step S6) such that a calcined alkaline earth metal carbonate results; and / or with the following additional step between the preparation or provision in step S1) and the reduction in step S2): S1 a) Heating the alkaline earth metal sulfate produced or provided in step S1), preferably heating to a temperature in the range of 400 °C to 1400 °C, preferably to a temperature in the range of 500 °C to 1300 °C, particularly preferably to a temperature in the range of 600 °C to 1100 °C, most preferably to a temperature in the range of 700 °C to 950 °C; and / or with the following additional step between the production or provision in step S1) and the reduction in step S2): S1 b) of the reducing gas produced or provided in step S1), preferably heating to a temperature in the range of 400 °C to 1400 °C, preferably to a temperature in the range of 500 °C to 1300 °C, particularly preferably to a temperature in the range of 600 °C to 1100 °C, most preferably to a temperature in the range of 700 °C to 950 °C.

6. Method according to any one of the preceding claims, wherein Step S2) of the procedure is carried out as a continuous process; or Step S2) of the process is carried out as a batch process; and / or wherein the alkaline earth metal carbonate precipitated as a solid in step S4); and / or the separated alkaline earth metal carbonate resulting in step S5); and / or the dried alkaline earth metal carbonate resulting in step S6); is selected from the group consisting of: Barium carbonate (BaCOs), preferably barium carbonate comprising less than 10 wt.% impurities, preferably less than 7 wt.%, particularly preferably less than 5 wt.%, most preferably less than 2 wt.%, in each case based on the total mass of barium carbonate and the included impurities; and / or less than 2 wt.% strontium oxide (SrO), preferably less than 1.8 wt.%, particularly preferably less than 1.6 wt.%, most preferably less than 1.45 wt.% % by weight, each based on the total mass of barium carbonate and the included minor constituents; and Strontium carbonate (SrCOs), preferably strontium carbonate comprising less than 10 wt.% impurities, preferably less than 7 wt.%, particularly preferably less than 5 wt.%, most preferably less than 2 wt.%, in each case based on the total mass of strontium carbonate and the included impurities; and / or less than 2 wt.% barium oxide (BaO), preferably less than 1.8 wt.%, particularly preferably less than 1.6 wt.%, most preferably less than 1.45 wt.%, in each case based on the total mass of strontium carbonate and the included impurities; and / or wherein the hydrogen sulfide resulting in step S4) is separated from the gas phase and / or - is further processed to sulfur dioxide and elemental sulfur; preferably in a Claus process; and / or is further processed to NaHS; and / or - is used in a chemical process that does not have elemental sulfur as the target product and does not have NaHS as the target product.

7. A method according to any one of the preceding claims, wherein step S2) of the method is carried out wholly or partly, preferably wholly, in a rotary kiln, and wherein the alkaline earth metal sulfate has a temperature in the range of 400 °C to 1400 °C when produced or provided in step S1), preferably a temperature in the range of 500 °C to 1300 °C, particularly preferably a temperature in the range of 600 °C to 1100 °C, and most preferably a temperature in the range of 700 °C to 950 °C; and / or wherein the reducing gas has a temperature in the range of 400 °C to 1400 °C when produced or provided in step S1), preferably a temperature in the range of 500 °C to 1300 °C, particularly preferably a temperature in the range of 600 °C to 1100 °C, and most preferably a temperature in the range of 700 °C to 1050 °C;and / or wherein the temperature during the process is in the range of 400 °C to 1400 °C, preferably in the range of 500 °C to 1200 °C, particularly preferably in the range of 600 °C to 1000 °C, most preferably in the range of 700 °C to 950 °C; and / or; wherein step S2) is carried out at a pressure in the range of 0.5 bar to 1.5 bar, preferably at a pressure in the range of 0.7 bar to 1.3 bar, particularly preferably at a pressure in the range of 0.8 bar to 1.2 bar, most preferably at a pressure in the range of 0.85 bar to 1.1 bar, preferably at a pressure in the range of 0.9 bar to 0.99 bar; and / or wherein in step S2) solids and reducing gas pass through the rotary kiln in countercurrent flow; and / or wherein, for heating the shaft kiln, reducing gas, preferably methane gas, is preheated to a temperature in the range of 500°C to 1300°C, preferably in the range of 600°C to 1100°C, particularly preferably in the range of 700°C to 1050°C in a preheater, preferably an electric preheater, before entering the shaft kiln;and / or wherein additional oxygen is supplied to the rotary kiln to heat it, so that a portion of the reducing gas introduced into the shaft kiln reacts in an exothermic reaction with oxygen in the shaft kiln; and / or wherein the rotary kiln is electrically heated; and / or wherein the gas mixture exiting the rotary kiln has a higher temperature than the solids entering the rotary kiln; and / or wherein the gas mixture exiting the rotary kiln is wholly or partially processed after exiting the rotary kiln, resulting in a processed gas mixture, and wherein the processing preferably comprises the removal of particulate substances; and / or the processing comprises the removal of water; and / or the processing comprises the removal of carbon dioxide (CO2); and / or Parts of the processed gas mixture are fed into the process as part of the reducing gas; and / or the particulate substances separated during the separation of particulate substances are fed into the process as part of the alkaline earth metal sulfate; and / or the gas mixture exiting the rotary kiln is used wholly or partially for heat recovery after exiting the rotary kiln.

8. A method according to any of the preceding claims, wherein step S2) of the method is carried out wholly or partly, preferably wholly, in a shaft furnace, and wherein the alkaline earth metal sulfate has a temperature in the range of 400 °C to 1400 °C when produced or provided in step S1), preferably a temperature in the range of 500 °C to 1300 °C, particularly preferably a temperature in the range of 600 °C to 1100 °C, and most particularly preferably a temperature in the range of 700 °C to 950 °C; and / or wherein the reducing gas, when manufactured or provided in step S1), has a temperature in the range of 400 °C to 1400 °C, preferably a temperature in the range of 500 °C to 1300 °C, particularly preferably a temperature in the range of 600 °C to 1100 °C, most preferably a temperature in the range of 700 °C to 1050 °C;and / or wherein step S2) is carried out at a pressure of 0.8 bar to 15 bar, preferably at a pressure of 3 bar to 10 bar, particularly preferably at a pressure of 4 bar to 8.5 bar, most preferably at a pressure of 6.5 bar to 7.8 bar; and / or wherein the height of the solid bed in the shaft furnace is in the range of 1 m to 30 m, preferably in the range of 2 m to 20 m, particularly preferably in the range of 6 m to 15 m, most preferably in the range of 8 m to 12 m; and / or; where in step S2) during reduction the bulk density of the solid in the shaft furnace is in the range of 0.6 t / m³ 3 up to 3.2 t / m 3 is preferably in the range of 0.9 t / m 3 up to 2.9 t / m 3 , particularly preferably in the range of 1.3 t / m 3 up to 2.7 t / m 3 , especially preferred in the range of 1.5 kg / m² 3 up to 2.6 kg / m² 3, each based on the mean bulk density of the entire solid bed; and / or wherein the temperature during the process is in the range of 400 °C to 1400 °C, preferably in the range of 500 °C to 1200 °C, particularly preferably in the range of 600 °C to 1000 °C, most preferably in the range of 700 °C to 950 °C; and / or wherein the alkaline earth metal sulfide resulting in step S2) leaves the shaft furnace at a temperature of less than 410 °C, preferably less than 400 °C, particularly preferably less than 390 °C, most preferably less than 385 °C; and / or wherein in step S2) solids and reducing gas pass through the shaft furnace in countercurrent flow; and / or wherein in step S2) the solids transport is gravity-driven; and / or wherein reducing gas with a temperature of less than 40 °C, preferably less than 35 °C, is used to cool the shaft furnace, particularly preferably less than 30 °C, very preferably less than 25 °C, is introduced into the shaft furnace; and / or wherein, for heating the shaft furnace, reducing gas, preferably methane gas, is preheated to a temperature in the range of 500 °C to 1300 °C, preferably 600 °C to 1100 °C, particularly preferably 700 °C to 1050 °C in a preheater, preferably an electric preheater, before entering the shaft furnace; and / or wherein, for heating the shaft furnace, oxygen is additionally supplied to the shaft furnace so that a portion of the reducing gas introduced into the shaft tube furnace reacts in an exothermic reaction with oxygen in the shaft tube furnace; and / or wherein the shaft furnace is electrically heated; and / or wherein the gas mixture exiting the shaft furnace has a higher temperature than the solids entering the shaft furnace;and / or wherein the gas mixture exiting the shaft furnace is wholly or partially processed after exiting the shaft furnace, resulting in a processed gas mixture, and wherein preferably; the processing includes the removal of particulate substances; and / or the processing includes the removal of water; and / or the processing includes the removal of carbon dioxide (CO2); and / or Parts of the processed gas mixture are fed into the process as part of the reducing gas; and / or the particulate substances separated during the separation of particulate substances are fed into the process as part of the alkaline earth metal sulfate; and / or the gas mixture exiting the shaft furnace is used wholly or partly for heat recovery after exiting the shaft furnace.

9. Method according to any of the preceding claims, wherein celestine is provided wholly or partially as the alkaline earth metal sulfate in step S1); or wherein the alkaline earth metal sulfate in step S1) is wholly or partly barite; and / or wherein the alkaline earth metal sulfate in step S1) is produced or provided in bulk, preferably as powdered bulk material and / or as granulated bulk material.

10. Production plant for the manufacture of an alkaline earth metal compound other than an alkaline earth metal sulfate, preferably an alkaline earth metal carbonate, particularly preferably an alkaline earth metal carbonate selected from the group consisting of: barium carbonate and strontium carbonate, wherein the production plant comprises at least: A) a device for producing or providing a reducing gas, preferably a reducing gas selected from the group consisting of: methane, hydrogen and ammonia; B) a device for producing or providing an alkaline earth metal sulfate, preferably an alkaline earth metal sulfate selected from the group consisting of: barium sulfate and strontium sulfate; C) a reactor for the reduction of an alkaline earth metal sulfate using a reducing gas.

11. Production plant according to claim 10, further comprising D) a container for an aqueous solution comprising a dissolved alkaline earth metal sulfide, wherein the container is preferably connected to a device for supplying water; and / or E) a stirring device for an aqueous solution comprising a dissolved alkaline earth metal sulfide; and / or F) a device for introducing carbon dioxide into a container for an aqueous solution comprising a dissolved alkaline earth metal sulfide; and / or G) a device for separating hydrogen sulfide, preferably a device for separating hydrogen sulfide comprising one or more containers in which the suspension containing the alkaline earth metal carbonate is passed through with gaseous carbon dioxide; and / or H) A device for separating solids, preferably alkaline earth metal carbonates, particularly preferably alkaline earth metal carbonates selected from the group consisting of: barium carbonate and strontium carbonate, from an aqueous solution; wherein the device is preferably selected from the group consisting of: centrifugation apparatus and filtration apparatus; particularly preferably the device is a centrifugation apparatus; and / or I) a device for drying solid alkaline earth metal carbonates; and / or J) a device for calcining alkaline earth metal carbonates; and / or K) a device for heating the reactor for the reduction of an alkaline earth metal sulfate by means of a reducing gas; and / or L) a device for heating an alkaline earth metal sulfate, preferably an alkaline earth metal sulfate selected from the group consisting of: barium sulfate and strontium sulfate, to temperatures in the range of 400 °C to 1400 °C, preferably to temperatures in the range of 500 °C to 1300 °C, particularly preferably to a temperature in the range of 600 °C to 1100 °C, most particularly preferably to a temperature in the range of 700 °C to 950 °C; and / or M) a device for heating a reducing gas, in particular methane and / or hydrogen, preferably for heating to a temperature in the range of 400 °C to 1400 °C, particularly preferably for heating to a temperature in the range of 700 °C to 1300 °C, most preferably to a temperature in the range of 750 °C to 1200 °C, very preferably to a temperature in the range of 800 °C to 1050 °C; and / or N) a device for drying an alkaline earth metal sulfate, preferably an alkaline earth metal sulfate selected from the group consisting of: barium sulfate and strontium sulfate.

12. Production plant according to one of the preceding claims 10 or 11, wherein the reactor C) for the reduction of an alkaline earth metal sulfate is selected from the group comprising reactors - Shaft furnace and - Rotary kiln; and / or wherein the reactor C) for the reduction of an alkaline earth metal sulfate is sealed in such a way that there are no unacceptable leaks of the reducing gas; and / or wherein the reactor C) for the reduction of an alkaline earth metal sulfate is a rotary kiln and is suitable for continuous operation; and / or wherein the reactor C) for the reduction of an alkaline earth metal sulfate is a shaft kiln and is suitable for quasi-continuous operation; and / or wherein the reactor C) for the reduction of an alkaline earth metal sulfate is suitable for operation, preferably continuous operation, at operating temperatures in the range of 400 °C to 1200 °C, preferably in the range of 500 °C to 1100 °C.

13. Production plant according to any one of the preceding claims 10 to 12, wherein reactor C) for the reduction of an alkaline earth metal sulfate is equipped with: an inlet opening for bulk solids, wherein the inlet opening for bulk solids is preferably equipped with a device for measuring the temperature of the bulk solids entering the inlet opening; and / or wherein the production plant has a device upstream of the inlet opening for bulk solids for measuring the mass and / or volume of the bulk solids entering the inlet opening; and / or an outlet opening for bulk solids wherein the outlet opening for bulk solids is preferably equipped with a device for measuring the temperature of the bulk solids exiting the outlet opening; and / or an inlet opening for reducing gas wherein the inlet opening for reducing gas is preferably equipped with a device for measuring the temperature of the reducing gas entering the inlet opening;and / or wherein the production plant is equipped with a device for measuring the mass and / or volume of the reducing gas entering the reactor; and / or an outlet for gaseous reaction byproducts; wherein the outlet opening for gaseous reaction products is preferably equipped with a device for measuring the temperature of the gaseous reaction products exiting the outlet opening; and / or wherein the production plant is equipped with a device for measuring the mass and / or volume of the gaseous reaction products exiting the outlet opening and / or wherein the production plant is equipped with a device for measuring the concentration of substances in the gaseous reaction products exiting the outlet opening.

14. Production plant according to any one of the preceding claims 10 to 13, wherein reactor C) for the reduction of an alkaline earth metal sulfate is a shaft furnace and wherein the shaft furnace is suitable for operating temperatures in the range of 400 °C to 1400 °C, preferably in the range of 500 °C to 1200 °C, particularly preferably in the range of 600 °C to 1000 °C, and most preferably in the range of 700 °C to 950 °C; and / or wherein the shaft furnace is not equipped with devices for the active mechanical conveying of solids; and / or wherein the shaft furnace is designed such that bulk solids are transported by gravity from an inlet opening for bulk solids to an outlet opening for bulk solids; and / or wherein the shaft furnace is equipped with an inlet opening for bulk solids and with an inlet opening for reducing gas, wherein these inlet openings are arranged such that a countercurrent of bulk solids and reducing gases can be generated in the shaft furnace; and / or wherein the shaft furnace is designed such that the inlet opening for bulk solids is designed as a lock system with movable flaps; and / or wherein the shaft furnace is equipped with an outlet opening for bulk solids, which is designed as a lock system with movable flaps; and / or wherein the shaft furnace is equipped with a temperature monitoring device with which the temperature of the bulk solids exiting through the discharge opening for bulk solids can be determined; and / or wherein the shaft furnace is equipped with a device for electrically heating the shaft furnace and the solids contained therein.

15. Production plant according to any one of the preceding claims 10 to 14, wherein reactor C) for the reduction of an alkaline earth metal sulfate is a rotary kiln, and wherein the rotary kiln is suitable for operating temperatures in the range of 500 °C to 1200 °C, preferably in the range of 600 °C to 1100 °C, particularly preferably in the range of 700 °C to 950 °C; and / or wherein the rotary kiln is equipped with devices for the active mixing of solids and gas phase; and / or wherein the rotary kiln is equipped with an inlet opening for bulk solids and is equipped with an inlet opening for reducing gas, wherein these inlet openings are arranged in such a way that a countercurrent of bulk solids and reducing gases can be generated in the rotary kiln; and / or wherein the production plant is designed in such a way that in front of the The rotary kiln's inlet opening for solids is equipped with a lock system, preferably a lock system with movable flaps; and / or the production plant is equipped with an outlet opening for bulk solids, which is designed as a lock system; and / or the rotary kiln is equipped with a temperature monitoring device with which the temperature of the bulk solids exiting through the outlet opening for bulk solids can be determined; and / or the rotary kiln is equipped with a device for electrically heating the rotary kiln and the solids contained therein.

16. Use of hydrogen and / or methane, preferably use of hydrogen, in a process for the production of an alkaline earth metal compound other than an alkaline earth metal sulfate, preferably an alkaline earth metal carbonate, preferably an alkaline earth metal carbonate selected from the group consisting of: barium carbonate and strontium carbonate, wherein the process is preferably a process according to any one of the preceding claims 1 to 9.

17. Kit for the preparation of an alkaline earth metal compound other than an alkaline earth metal sulfate, preferably for the preparation of an alkaline earth metal carbonate, particularly preferably for the preparation of an alkaline earth metal carbonate selected from the group consisting of: barium carbonate and strontium carbonate, comprising at least: a sulfate compound, preferably barium sulfate and / or strontium sulfate; and a reducing gas, preferably methane and / or hydrogen, particularly preferably hydrogen.

18. Use of a kit according to the preceding claim 17 for the production of an alkaline earth metal compound other than an alkaline earth metal sulfate, preferably for the production of an alkaline earth metal carbonate, particularly preferably for the production of an alkaline earth metal carbonate selected from the group consisting of: barium carbonate and strontium carbonate, wherein the method is preferably a method according to any one of the preceding claims 1 to 9.

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