Method for manufacturing manganese sulphate component from manganese-containing material of zinc electrolysis, manganese sulphate component and its use

Abstract

The invention relates to a method for manufacturing a manganese sulphate component (24) from a manganese-containing material (11) of zinc electrolysis. In the method the manganese-containing material is dissolved (101, 201, 402) in the presence of water (12), sulphuric acid (13) and at least one reducing agent (14) to form a suspension (25); a process solution (15) is formed from the suspension by separating (102, 202, 403) there from a first precipitate (16) containing at least lead (17) and silver (18); metals and / or metal compounds, including one or more of the following: zinc (20), copper (21), is precipitated (103, 203, 408) from the process solution by using at least one sulphide source (19), and a precipitate (23) containing metal sulphides (22) is separated (104, 204, 409) from the process solution, after which the manganese sulphate component formed is suitable for use as a fertiliser (24.1) in agriculture or as an industrial raw material (24.2). Furthermore, the invention also relates to the manganese sulphate component, the use and the product thereof.

Description

[0001] METHOD FOR MANUFACTURING MANGANESE SULPHATE COMPONENT FROM MANGANESE— CONTAINING MATERIAL OF ZINC ELECTROLYSIS, MANGANESE SULPHATE COMPONENT AND ITS USE AND PRODUCT

[0002] The invention relates to a method for manufacturing a manganese sulphate component from manganese-cont aining material of zinc electrolysis. Furthermore, the invention also relates to a manganese sulphate component and its use and to a product.

[0003] In zinc electrolysis, the zinc contained in the roasted zinc concentrate is first dissolved in sulphuric acid. This zinc sulphate solution is then electrolysed, causing the zinc to adhere to the surface of the aluminium cathode. Once the zinc layer has grown thick enough, the zinc is removed from the cathode and the cathode is returned to the process. Lead, on the other hand, serves as the anode material in electrolysis. It is alloyed with some silver to improve the properties of the cathode. The anode contains 0.6 to 1.0% by weight of silver. The purpose of the silver is to make the lead anode stronger. It also catalyses the evolution of oxygen.

[0004] Zinc concentrate contains some manganese, which dissolves, but is not removed during solution purification. During electrolysis, this manganese is oxidised to manganese dioxide on the anode surface. This presence of manganese also protects the anode from excessive corrosion and extends the service life of the anode. The forming manganese dioxide forms layers on the anode surface, which over time sink to the bottom of the electrolysis tanks. Therefore, the electrolysis tanks must be maintained and cleaned at certain intervals.

[0005] Anode slurry containing manganese from the zinc industry is treated as landfill waste. If not carried out with appropriate protection measures, which in turn will result in costs, landfilling will cause environmental problems. Large quantities of anode slurry are generated annually as a result of continuous industrial activity. In this case, large areas of land must be reserved for its final disposal. This procedure is not appropriate, as manganese is currently classified as a critical raw material in several market areas. Therefore, its recycling should be significantly enhanced.

[0006] The state-of-the-art publication US 2024 / 0076199 Al is known. It describes a reductive acid dissolution of manganese-contain- ing material of zinc electrolysis. Acid dissolution is followed by sulphide precipitation. The end result of this method is a crystallised manganese sulphate component. There are a number of problems associated with this solution that, for example, make the overall economics of the method less favourable.

[0007] It is an object of the present invention to provide a method for manufacturing a manganese sulphate component, wherein the manganese-cont aining material originating from zinc electrolysis is used to produce an end product, which is a manganese sulphate solution suitable for use as an agricultural fertiliser and / or as an industrial manganese-containing raw material. The characteristic features of the method according to the invention are presented in Claim 1. In addition, the object of the invention is to provide a corresponding apparatus, manganese sulphate component, its use and a product. The characteristic features of these are presented in Claims 25 and 28 to 30.

[0008] In the invention, metals and metal compounds are removed from manganese-containing material originating from zinc electrolysis by chemical methods, whereby as the end result of the method is obtained an aqueous manganese sulphate component. It is suitable for use as an agricultural fertiliser or as an industrial raw material.

[0009] According to a first embodiment, as a sub-step of the method, an aqueous acid dissolution of manganese-containing material originating from zinc electrolysis is carried out in the presence of at least one reducing agent and the precipitate formed in the acid dissolution is separated from the resulting solution. As a result, the manganese sulphate solution component formed is suitable as such for agricultural use.

[0010] According to another embodiment of the invention, the process solution formed after the acid dissolution and subsequent precipitate separation is subjected to sulphide precipitation using at least one sulphide source. It now forms a second precipitate that can be separated from the process solution. The manganese sulphate solution component formed after this precipitate separation is suitable for agricultural use and also as a raw material for industry. The second precipitate, including mainly zinc in the sulphide form, is as such suitable as a raw material for the zinc industry. In addition, the second precipitate is free of the substances removed in the first precipitate separation. This useful by-product in the form of metal sulphides improves the overall economics of the method.

[0011] The separation of the first precipitate at the end of the acid dissolution before sulphide precipitation has a beneficial effect on the chemical consumption of the method. The first precipitate is sulphates and the second precipitate is sulphides. In this case, the separation of the first precipitate before sulphide precipitation improves the overall economics of the method, because less of the chemical used in the sulphide precipitation is consumed. If the sulphide precipitate and the sulphate precipitate were mixed, the chemical consumption in sulphide precipitation would increase considerably, because the chemical used in it would then also react with the sulphates. In addition, in this case, the mixed precipitate obtained from sulphide precipitation, including a significant amount of sulphates and metal sulphides, would be less suitable for further utilisation. As already stated above, by means of the precipitate separation taking place before sulphide precipitation, the sulphide precipitate formed in sulphide precipitation is suitable as such for use as a raw material in the zinc industry, because its composition is largely zinc as metal sulphide.

[0012] According to one embodiment of the method, the method may include, in both of the above mentioned embodiments, reducing the iron content of the suspension and / or the process solution. According to one embodiment, iron may be precipitated to be as part of the first precipitate. In this case, the iron precipitation step is carried out after the acid dissolution step. Even then, the method can be carried out, according to its first embodiment, with only one precipitate separation or, according to its second embodiment, with only two precipitate separations. Another way to reduce the iron content of the process solution is through sulphide precipitation itself.

[0013] According to one embodiment of the method, the method may include, again in both of the above mentioned embodiments, at least one sub-step assembly of changing the manganese oxidation number to ensure that the end product remains in solution form. After the dissolution step, the suspension and the process solution subsequently formed from it may still contain manganese forms with undesirable oxidation numbers. These will later result in, for example, precipitation of the end product in the form of solid manganese dioxide. The presence of these undesirable oxidation number forms can be detected from the colour of the process solution. In the processing of the manganese oxidation number, the oxidation number desired appears as a pink colour of the process solution. If the colour of the solution is anything other than pink, it can be concluded that the process solution then contains undesirable and therefore precipitable manganese oxidation number forms. As a result of the observation, the process solution is subjected to processing that change the manganese oxidation number in the process solution to a favourable, non-precipitating form.

[0014] Changing the manganese oxidation number can be carried out, for example, after acid dissolution and also after a possible subsequent iron precipitation, if it is separately used as one embodiment. Changing the manganese oxidation number can be done in the solution according to a first embodiment by pH adjustment. In this case, the pH is first lowered by adding sulphuric acid and then raised by adding metallic zinc. One advantage of this embodiment is that, according to one embodiment, this same processing also reduces the cadmium content of the solution. With a suitable reagent used for pH adjustment, in this case zinc, this occurs as a side effect of changing the manganese oxidation number. According to another embodiment, changing the manganese oxidation number can also be carried out by using sodium sulphite as a chemical. As already stated, according to one embodiment, the need for changing the manganese oxidation number can be determined by visual inspection of the solution. It is a simple and quick procedure and does not require special equipment .

[0015] According to one embodiment, the material to be processed by the method according to the invention, i.e. , the manganese- containing material of zinc electrolysis, is moist. This has advantages, for example, in terms of pre-treatment of the material before its chemical treatment. According to one embodiment, the precipitate separation after the dissolution step of the manganese-containing material can be divided into two parts, coarse filtration of the suspension formed and subsequent fine filtration. In coarse filtration, the coarse material that has not dissolved in the dissolution step is first removed from the suspension-shaped process solution formed during dissolution. This includes, in addition to other possible waste materials such as stones, for example, manganese-containing material insoluble in dissolution step, i.e. , the process starting material, which is present in the coarsely filtered material as particles of different sizes. It is also possible to speak of screening a suspension of solids, through which a suspension of the liquid fraction of the solution and the fine sulphate precipitate, which is mainly formed during the dissolution, passes. The separated coarse manganese- containing solids can be treated in a selected manner after dissolution and then possibly redirected to the dissolution step. After coarse filtration, fine filtration of the suspension that has passed through screening is carried out. In that, from the suspension are separated the finely divided sulphate precipitate, which has a more homogenous particle composition formed during dissolution, and the process solution.

[0016] According to one embodiment, the discharge of the dissolution reactor can take place in two stages. The first stage can be the discharging of the coarse material insoluble in dissolution step from the reactor. It is carried out using a liquid-assisted method. It uses the suspension formed during the dissolution step to assist in emptying of the reactor and transferring the coarse material to the separation means. More specifically, according to one embodiment, emptying of the reactor and transfer of the material to the separation means can also be referred to as a dilution transfer. Despite the challenging starting material, like the manganese-containing material as a waste fraction of zinc electrolysis is, this method ensures a smoother, safer and more continuous reactor discharge and transfer of the coarse material to the separation means in a simple arrangement. The dilution transfer utilises the recycling of the suspension into the reactor through the screening apparatus and / or upstream of the screening apparatus. This ensures a sufficient amount of liquid, more specifically, sufficient liquid / solids ratio, in the reactor at all times, so that coarse material can also be removed from the reactor and forwarded to the separation means without any problems.

[0017] According to one embodiment, the separation of the sulphate precipitate from the process solution involves washing the separation means and the sulphate precipitate. The sulphate precipitate contains soluble manganese, which is washed off with washing water. The manganese-cont aining washing water can then be used as a base solution for the dissolution. In addition, this also improves the further processability of the sulphate precipitate component. Other additional advantages of the invention are apparent from the description and the characteristic features from the accompanying Claims.

[0018] The invention, which is not limited to the embodiments presented below, is described in more detail by reference to the accompanying figures, wherein

[0019] Figure la shows as a rough block diagram the sub-steps of the method according to the invention in a first embodiment ,

[0020] Figure lb shows as a rough block diagram the sub-steps of the method according to the invention in another embodiment ,

[0021] Figure 2a shows a first example of the method according to the invention as a rough flow diagram, Figure 2b shows a second example of the method according to the invention as a rough flow diagram,

[0022] Figure 3a shows a schematic diagram of an apparatus according to the invention in the case of the flow diagram shown in Figure 2b,

[0023] Figure 3b shows an embodiment of reactor discharging as a schematic diagram,

[0024] Figure 4 shows an example as a flow diagram of a slightly more advanced embodiment of the invention,

[0025] Figure 5 shows a schematic diagram of the apparatus according to the invention in the case of the flow diagram shown in Figure 4,

[0026] Figure 6 shows an embodiment of the sub-steps related to the acid dissolution of manganese-containing material of zinc electrolysis,

[0027] Figure 7 shows an embodiment for precipitation of iron from a suspension into a first precipitate,

[0028] Figure 8a shows a first embodiment of the sub-steps for changing the manganese oxidation number in the process solution and the concomitant removal of cadmium,

[0029] Figure 8b shows another embodiment of the sub-steps for changing the manganese oxidation number in the process solution,

[0030] Figure 9 shows an embodiment of the sub-steps for separating sulphide precipitate from the process solution,

[0031] Figure 10 shows as a rough block diagram another embodiment of the method according to the invention, including the iron precipitation shown in Figure 7,

[0032] Figure 11 shows as a rough block diagram a third embodiment of the method according to the invention, including changing the manganese oxidation number shown in Figure 8a,

[0033] Figure 12 shows as a rough block diagram a fourth embodiment of the method according to the invention, including the steps of the flow diagram shown in Figure 4, and

[0034] Figure 13 shows as a rough block diagram a fifth embodiment of the method according to the invention, including (only) at least one precipitate separation .

[0035] Figures la and lb show, as rough block diagrams, some examples of an industrial method according to the invention for manufacturing a manganese sulphate component from manganese-con- taining material of zinc electrolysis. Thus, zinc electrolysis can be characterised as a secondary source of manganese in the context of the invention. The manganese-cont aining material, in turn, can be characterised in the context of the invention as a material originating from a secondary source of manganese. Currently, manganese-cont aining material originating from zinc electrolysis is classified as a waste fraction that must be disposed of in accordance with environmental laws and regulations. It accumulates in significant quantities from electrolytic zinc production and its main disposal method has been landfilling .

[0036] Here, an industrial method, as distinguished from, for example, a laboratory-scale operation, refers to an activity that has the potential to process tons of starting raw material into an end product on a daily basis. In step 101 of the method, the dissolution of the manganese-containing material is carried out. The purpose of this is to form a manganese sulphate component from a manganese-containing material by acid dissolution, which is then treated in accordance with the method to provide a pure MnSCq solution as the end product of the method. In the method, a precipitate is formed in the manganese sulphate component in at least one sub-step 101, 103, belonging to the method which is also separated from the manganese sulphate component in the subsequent at least one sub-step 102, 104. The precipitate removes metals and metal compounds other than manganese that were present in the material 11 and thus also dissolved in the manganese sulphate component formed from it.

[0037] Figure 2a shows a first example of the method according to the invention as a flow diagram, which corresponds to the block diagram of Figure la. Reference is also made to the apparatus diagram in Figure 3a. In step 201 of the method, the manganese- containing material 11 is dissolved in the presence of water 12, sulphuric acid 13 and at least one reducing agent 14 to form a suspension 25. The dissolution takes place in a reactor 31. Water 12 forms an aqueous matrix for the sulphate formed during the acid dissolution of the manganese-containing material 11, into which matrix the dissolution takes place. During the dissolution, sulphuric acid 13 and at least one reducing agent 14 react with the manganese dioxide present in solid form in the manganese-containing material 11. In this case, they break down the structure of manganese dioxide (MnCg) and convert the manganese released from it into manganese sulphate (MnSCy) in the aqueous solution.

[0038] Water 12 can be, for example, tap water. In addition to tap water, the washing water 43' of the lead-silver precipitate to be separated later from the suspension 25, i.e. , the first precipitate 16, can also be used as water (Figure 3a) . It is produced from the filtration step 32 of the suspension 25. The wash water 43' contains manganese residue left in the precipitate 16, which is recovered by recycling the wash water 43' . The wash water 43' can be recycled to the next dissolution batch as its base solution.

[0039] As an acid, sulphuric acid 13 is a preferred dissolving chemical for use in the method according to the invention, for example because in the battery industry, which is an exemplary application for the end product 24.2 of the method according to the invention, battery materials, including manganese, are produced by precipitating metals as solid hydroxides out of a sulphate solution, leaving a sodium sulphate solution. The use of sulphuric acid 13 for dissolution results in the formation of manganese sulphate in solution form, from which the manganese is subsequently precipitated as hydroxide. Dissolving solid manganese sulphate in water is well known from industrial processes and also from the prior art. Manganese sulphate is then in solid form and powdery. In this case, it dusts when poured into water, creating occupational safety hazards (manganism) . However, in the case of the product according to the invention, the product is, according to one embodiment, in aqueous solution form, i.e. , already in liquid form, eliminating the dangerous dusty work step characteristic of the known method in later applications of the manganese sulphate component. In addition, sulphuric acid 13 has the added advantage over other acids suitable for use for the same purpose that sulphuric acid 13 does not introduce into the process such components that would later have to be removed by elimination before the use of the end product, i.e. , the manganese sulphate component 24.

[0040] When already in liquid form after the treatment process according to the invention, the manufacturing of the product consumes less energy compared to, for example, embodiments that involve converting the liquid manganese sulphate component into a solid form, for example, by evaporation. Thus, the formed aqueous solution of manganese sulphate component 24 is suitable for use as a fertiliser 24.1 in agriculture or as an industrial raw material 24.2 without solidification of the manganese sulphate component 24, for example by crystallisation, before its use.

[0041] The reducing agent 14 used in the dissolution may be one or more selected from the following: peroxide 14 ' , citric acid, one or more sugars. Among these examples, peroxide 14 ' , such as, for example, hydrogen peroxide 14*, is the most preferred because it is more effective than the other exemplary reducing agents 14. In addition, only water remains in the process as a residue from peroxide 14 ' , and no residues of, for example, organic carbon.

[0042] Peroxide 14 ' is added during the dissolution step, more specifically at the end thereof, so that for the suspension 25, a value range of pH = 3 to 4 is reached. This is a preferred pH range for, for example, pipelines and also for filter structures. Furthermore, the use of peroxide 14 ' for pH adjustment purposes is also advantageous because, for example, in the subsequent filtration of the suspension 25, the use of peroxide 14 ' as a pH adjuster ensures the functionality of the filter means 32, compared to, for example, hydroxides, such as, for example, sodium hydroxide, which would be a logical choice as a pH adjuster due to its affordability and availability. The applicant has observed in the pilot phase tests of the method that, for example, sodium hydroxide, when used as a neutralising chemical, causes problems in the form of filter clogging because it forms a very fine precipitate in the process according to the invention.

[0043] In the presented embodiment, in step 202, the process solution 15 is formed by separating the first precipitate 16 from the suspension 25. Thus, the first precipitate 16 originates already from the formation step 201 of the suspension 25, i.e. , from the dissolution of the manganese-containing material 11 in the presence of water 12, sulphuric acid 13 and at least one reducing agent 14. Thus, two functions are achieved in the same single method step 201, namely the dissolution of the material 11 and, in addition, the formation of the first precipitate 16 in the suspension 25 formed during the dissolution.

[0044] The first precipitate 16 includes at least lead 17, silver 18 and calcium 44 originating from the manganese-containing material 11. They are present in the precipitate 16 as the corresponding sulphates. These substances removed with the solid dissolution residue are formed into sulphates at the latest in this dissolution step, if they are not already that in the first place. At this point the first precipitate 16 is present in the entire solution volume, which is thus a suspension 25.

[0045] The separation of the first precipitate 16 can be done, for example, with a suitable filtration means 32. As an example of such, a frame filter 32 ' can be mentioned.

[0046] In connection with the filtration means 32, the precipitate 16 is additionally washed with the washing water 43. For it an inlet and recovery is arranged in connection with the filtration means 32. The precipitate 16 is washed because it is advantageous for the further treatment of the precipitate component that it forms that there is only very little manganese present in the precipitate 16, which would remain in the precipitate 16 during the drying of the manganese sulphate left therein. As already stated earlier, the manganese-containing washing water 43' from the washing the precipitate 16 can be utilised by using it as a base solution in the dissolution method step 201, instead of / in addition to clean water 12. In the case of the embodiment presented, the filtration means 32 is a horizontal frame filter 32 ' . Washing of the precipitate 16 can be done after the filter chambers of the frame filter 32 ' are filled, i.e. before the filter is discharged. In this case, the washing water flows through the precipitate cakes and rinses away the manganese solution in the precipitate 16. This manganese-cont aining washing water 43' is collected, for example, in washing water tank downstream the filtering means. From there, it can then be returned as a raw material for the next dissolution process. Once the washing step of the precipitate 16 has been completed, the filter chambers are opened and the precipitate cakes are dropped out of the filter means. After this, the chambers are closed and the filtration is continued with a new batch of bulk solution, i.e. suspension 25.

[0047] The amount of dry lead-silver precipitate 16 containing calcium crystals 44 is approximately 25 to 40% of the dry weight of the manganese-cont aining material 11 fed to the dissolution reactor 31. In other words, if 100 g of manganese-containing material 11 is fed, having a moisture content of, for example 30%, 70 g of dry material 11 enters the reactor 31, of which 25 to 40% will end up as lead-silver precipitate 16 and calcium crystals 44. The manganese sulphate solution 24 formed after filtration of the lead-silver precipitate 16 is suitable for use as a fertiliser 24.1 in agriculture. However, it can still be processed, for example, by iron precipitation (before precipitate separation 202) and / or manganese oxidation number adjustment (after precipitate separation 202) as described below in the description. However, the manganese sulphate solution 24 for agricultural use does not necessarily require sulphide precipitation (Figure 2b, reference numbers 203, 204) , which is subsequently performed on the process solution 15 as one of the main steps of the method. Figure 2b shows another example of the method according to the invention as a flow diagram and Figure 3a shows the corresponding apparatus diagram at a slightly more detailed level. For steps 201 and 202, reference is made to the explanations of Figure 2a. The presented embodiment extends the range of applications of the manganese sulphate solution 24 from agricultural use also to industrial use. Nevertheless, the implementation at the apparatus level remains relatively simple, but still versatile. In manufacturing, the transition from one product to another is rapid and, as a manufacturing process, does not require major modifications to the existing apparatus 10 nor to the apparatus 10 being purchased.

[0048] Once the process solution 15 is completed, i.e. after the first precipitate separation 202, metals and / or metal compounds are precipitated from the process solution 15 using at least one sulphide source 19 in step 203. The sulphide precipitable process solution 15 is a filtrate separated from the suspension 25 formed in the reductive acid dissolution. The reductive acid dissolution, in which the sulphide precipitable process solution 15 is formed, is therefore the first and also the only acid dissolution step of the method. The sulphide precipitation may have its own reactor 34 in the apparatus 10. In the sulphide precipitation, the substances that are separated from the process solution 15 precipitate as metal sulphides 22. The metals or sulphide compounds including them that precipitate in the precipitate 23 include one or more of the metals that were present in the manganese-containing material 11. Examples include zinc 20, copper 21, cadmium 30, 30.1, and iron 27, 27.1.

[0049] In step 204, a precipitate 23 including metal sulphides 22, and now a second precipitate in the order, is separated from the process solution 15. This is mainly zinc sulphide, but other metals already mentioned above are also present as precipitated metal sulphides 22. The manganese sulphate solution 24 formed after this is suitable for use as such, for example as a fertiliser 24.1 in agriculture and also as an industrial raw material 24.2.

[0050] Figure 4 shows an example of an industrial scale of the method according to the invention as a flow diagram, and Figure 5 shows a corresponding apparatus diagram as an even more detailed example of an embodiment that the previously presented examples of embodiments. However, a person skilled in the art will appreciate that the more detailed implementation shown in the figures and in this application is only one punctual application example of the method. The different sub-assemblies of the method presented and their proposed ways of implementation achieve different, even mutually independent, inventive advantages. Thus, not all of the sub-assemblies and steps shown, for example, in Figures 4 and 5, and their more detailed substeps, shown in Figures 6 to 9, are absolutely necessary to implement the concept and to achieve the advantages according to the invention. Moreover, all sub-steps (for example, reducing the iron content and / or changing the manganese oxidation number in the process solution 15) can be advantageously combined in an arbitrary order and also utilised in the application of Figure 2a, which lacks, for example, sulphide precipitation.

[0051] The raw material of the method according to the invention, i.e. the manganese-cont aining material 11 originating from zinc electrolysis, include manganese dioxide. As has already been mentioned in the description of the prior art, the manganese- containing material 11 is formed in the electrolysis process of zinc concentrate at the bottom of the electrolysis tank. From time to time it is scraped off from there. According to one embodiment, instead of intermediate landfilling, the material 11 can be collected directly from the tank as manganese slurry 11' , i.e. wet, for example, into suitable transport containers. The material 11 can be delivered to the processing according to the invention by means of the transport containers and can also be fed directly from them to the processing method according to the invention. This avoids contamination from the landfilling phase, such as, for example, the entry of rocks and / or foreign chemicals into the manganese-containing material 11. In addition, it has been observed that the manganese-containing material 11 originating from the zinc electrolysis is transferred more efficiently as wet manganese slurry 11 ' through the vibrating screen 42 used in the pre-screening of the manganese slurry 11 ' than the dry material. This is because the manganese slurry 11 ' contains aqueous soluble sulphate, which is prone to caking when it dries. As the material 11 dries, the soluble sulphate in the material 11 and thus also in the manganese slurry 11 ' solidifies as the water evaporates. When drier, the manganese-containing material 11 from zinc electrolysis also generates dust, which is a working safety hazard. Of course, it is also possible to use the manganese- containing material 11 from landfilling, but with the manganese slurry 11 ' supplied wet directly to the method from the bottom of the tank at least the above-mentioned advantages are achieved, and also the collection and treatment of seepage waters associated with the landfilling is avoided. Thus, the moisture content of the manganese-containing material 11 of zinc electrolysis used as a feedstock in the method can be, according to one embodiment, for example 30 to 55%, more particularly 35 to 50%.

[0052] In the process plant, the manganese-containing material 11 can be transferred to the reactor 31, for example, by a conveyor. The feeding from the transport container to the conveyor can take place such that upstream to the conveyor, more generally, prior to the reactor 31, the manganese-containing material 11 is pre-screened 42 in step 401. According to one embodiment, it can be implemented, for example, with a grid and / or screening mesh 42 ' equipped with vibration motors. The purpose of the pre-screening 42 is to remove particles from the manganese- containing material 11 originating from the zinc concentrate electrolysis method, which are unwanted by the process apparatus 10. Such particles include, for example, stones, concrete fragments and any plastic debris that may accompany the manga- nese-cont aining material 11.

[0053] If the manganese-containing material 11 is slightly moist, the vibration also breaks up the clumped wet mass, which then easily flows down through the screening mesh. If the force of the vibration motors is also applied to the feed silo below the mesh, the mass will easily flow along the sides of the feed silo onto the conveyor. For this purpose, a mechanical connection has also been arranged from the vibration motor to the feed silo.

[0054] In step 402, the manganese-containing material 11, now manganese slurry 11' , of zinc electrolysis is dissolved in water 12, acid 13 and at least one reducing agent 14. As already stated earlier in connection with figures 2a and 2b, this step can also be called the formation of the suspension 25. According to the sub-step flow diagram shown in Figure 6, according to one embodiment, step 402, i.e. the formation of the suspension 25, may be divided into a number of sub-steps 601 to 607, one possible combination of which is presented as an example below. According to one embodiment, the reactor 31 precharged with water 12 in step 601 is charged in step 602 according to the lowest assumed manganese content of the manganese-containing material 11 to be dissolved. In other words, the reactor 31 is initially charged with high manganese slurry 11 ' and low water 12 content. According to one embodiment, the default value for the manganese content of the material 11 can be, for example, 25% by weight. However, it can naturally be lower or higher than this, if the content in the material 11 to be processed is typically even lower or higher. In step 603, mixing the manganese-containing material 11 with water 12 forms a suspension 25.

[0055] During the formation of the suspension 25 of the manganese- containing material 11 and water 12, at least one sample 26 of the suspension 25 is taken from the reactor 31 in step 604 for the determination its manganese content in step 605. i. In this case, before the final formation of the suspension 25, i.e. the addition of other chemicals involved, i.e. sulphuric acid 13 and at least one reducing agent 14 to the reactor 31, several samples 26 of the suspension 25 formed by the material 11 and water 12 are taken from the reactor 31 to determine the exact manganese content of the solid component of the material 11, i.e. the feedstock. By taking one or more samples 26 from the suspension 25, a very precise concentration value of the total combined material 11 fed to the reactor 31 can be determined compared to a spot sample taken from the material 11 itself. If samples were taken directly from separate solids containers before the manganese-containing material 11 is fed into the reactor 31, their manganese content could vary greatly due to significant internal concentration variations in the manganese slurry 11 ' . By taking a sample 26 from a finished combination of several mass batches, a significantly more reliable concentration data can be obtained.

[0056] Once the suspension 25 of the material 11 and water 12 has been formed and the samples 26 have been taken from it, the dissolution of the material 11, i.e. the formation of the final suspension 25, is started by dosing in step 605.1 sulphuric acid 13 into the suspension 25 of the manganese-containing material 11 and water 12 to be processed and formed in the reactor 31. In this step, sulphuric acid 13 is added into the suspension 25 in the reactor 31 according to the calculated amount of the lowest assumed manganese content of the manganese-containing material 11.

[0057] In step 605. i, the exact manganese content of the solid component of the material 11 is determined from one or more samples 26 taken from the suspension 25. At the same time, however, the dissolution of the manganese-containing material 11 with water 12 and sulphuric acid 13 is already in full swing. In the content determination step 605. i, one or more samples 26 previously taken from the reactor 31 are decomposed for analysis to determine their exact manganese content. Here, the solids and liquid belonging to the suspension 25 are first suction filtered, leaving the solids on the paper. The suction-filtered solids can be rinsed with clean hot water before taking the sample 26 to be analysed. In this way, any soluble manganese amounts in the manganese sample precipitate, which may be present in the washing waters 43' obtained from the subsequent filtration stages 32 fed to the reactor 31, can be rinsed out of the solid manganese sample precipitate, thus from distorting the solids concentration determination result.

[0058] After this, water-washed solids are added into sample tubes, to which concentrated acids are also added. Then the tubes are placed in the laboratory's microwave disintegrator for about an hour. As a result the tubes will contain liquid, which is diluted and then analysed for its manganese content. Once these have been determined, a calculation is made in step 606. ii of how much manganese the mass placed in the tubes originally contained. An alternative method is to perform the determination by solids analysis. The analytic apparatus arrangement is referred to in Figure 5 by reference number 35. Once the manganese content of the solids has been determined, it is entered into the batch report, as a result of which the report counter 36 indicates how much sulphuric acid 13 and water 12 are still to be added to the reactor 31. In addition, the final amount of the reducing agent 14 to be added to form the suspension 25 is also clarified here. However, the feeding of the reducing agent 14 may already be in progress and started as step 605.2 during and / or after the initial sulphuric acid addition, possibly before the result of the precise concentration determination is known. During the concentration determination, i.e. step 606.1, the dissolution of the material 11 in water 12, sulphuric acid 13 and reducing agent 14 may already be in progress.

[0059] The counters 36 are based on the amount of manganese. The dissolution formula is:

[0060] MnO2+ H2SO4 + H2O2 — > MnSO4+ 2 H20 + 02(1)

[0061] It shows that for one mole of manganese, at least one mole of acid and at least one mole of peroxide are required. Once the amount of manganese itself has been precisely determined by the above-mentioned decomposition experiments, it is possible to say how much manganese was contained in the mass fed to the reactor 31 and, therefore, how much chemicals its (optimal) dissolution will require as a minimum.

[0062] Once the manganese content of the material 11 is confirmed, in step 607 the suspension 25 is finalised by adding the necessary additional amounts of water 12, sulphuric acid 13 and / or at least one reducing agent 14 based on the exact manganese content of the material 11 determined in step 605. i. If, for example, hydrogen peroxide 14* is used as reducing agent 14, it is slowly / moderately pumped into the reactor 31 in a final amount calculated according to the concentrations. Subsequently, the amounts of substances 12 to 14 correspond at least to the higher and more real manganese content measured in the material sample 26.

[0063] The reactor 31 may include a possible defoamer. According to a first embodiment, it can be implemented by feeding at least one defoamer. The defoamer is resistant to acidic conditions and is preferably biodegradable. Another possibility to implement the antifoam treatment is by spraying a mist of, for example, water 12, sulphuric acid 13 and hydrogen peroxide 14* into the foam. According to an embodiment, the feed of hydrogen peroxide 14* to the reactor 31 may be arranged below the surface of the suspension 25. This may prevent premature decomposition of hydrogen peroxide 14* during the formation of the suspension 25. In addition, by pumping hydrogen peroxide 14* below the surface, it is better contacted with the manganese particles of the suspension 25 and thus works more efficiently.

[0064] The reactor 31 is equipped with cooling 37, at least for the start of the dissolution process, because the process is highly exothermic. In addition, cooling the temperature of the reactor 31 to 40°C or preferably even lower reduces the strong gas and mist formation developed by the hydrogen peroxide 14*. The cooling 37 makes it easier to see into the reactor 31, because the reactor 31 is less likely to form a mist. In a later stage, the temperature can be raised to approximately 50 to 60°C once the layer of foam layer has formed on the surface of the reactor 31. The foam layer keeps the mist formation under control, maintaining the visibility into the reactor 31. Raising the temperature also improves the solubility of the manganese granules. In this way, less solid fraction 64 goes to the screen 45 following the dissolution step and the screening 45* proceeds faster. The reactor 31 may also have a breaking "whip" 38 or similar fitted to the upper part of the shaft of the mixer 39 to keep the rising foam layer under control. A further option for implementing the anti-foaming may be the use of ultrasound (not shown) .

[0065] The advantage of this embodiment, i.e. the sampling process and especially the analysis before the final dosing of the process chemicals 12 to 14, is that the dissolution process of the material 11 with the chemicals, especially sulphuric acid 13, can be started immediately, i.e. even before the concentration analyses are completed. If the lowest concentration of the material 11 is assumed to be 25% by weight manganese (25 to 45% by weight) , the initial chemical quantities are obtained from the calculator 36. However, since the manganese content in the material 11 is usually higher (typically about 30 to 45% by weight, but more generally 25 to 50% by weight) , the chemicals 13 and 14 are added later, already while the dissolution is in progress, in excess of what was initially calculated and this additional amount is determined when a mass sample is got analysed from the mass belonging to the suspension 25, i.e. , the material 11. Thus, by using this 25% by weight assumption of the material 11 concentration, the final analysis result does not need to wait before starting the dissolution process, but the start 606.1 of the process and the analysis 605. i, 606. ii of the sample 26 can be run in parallel.

[0066] During the formation step 402 of the suspension 25, its manganese content can be monitored by intermediate analyses. In addition, the colour of the suspension 25 can possibly be monitored, for example, by observing filtered intermediate samples to visually monitor the progress of the dissolution. Returning to Figure 4, according to one embodiment of the method, the method can also include at least one step 403, in which iron 27.2 is removed from the manganese sulphate component. This step can be implemented in several different ways. Furthermore, it can be implemented at different points in the overall process. According to one embodiment, iron 27.2 can be removed from the suspension 25 by precipitating it to be as part of the first precipitate 16, which is formed during the dissolution step 402 of the manganese-containing material 11. In this case, at the end of the dissolution step 402 of the manganese-containing material 11, the pH of the suspension 25 is adjusted in step 403 to precipitate iron 27.2 to be as part of the first precipitate 16. At the end of the dissolution step, the pH of the suspension 25 is then in the range of pH = 3 to 4.

[0067] As shown in Figure 7, according to one embodiment, step 403, i.e. the precipitation of iron 27.2 as a separate sub-step from the suspension 25 after its formation / at the end of its formation, may be divided into several sub-steps 701 to 703, one possible combination of which is presented as an example below. Some of the reasons for removal of iron include, for example, the possible formation of iron precipitate in the end product. Iron-containing solids are sticky and can clog farmers' sprayers when manganese sulphate solution is used as a fertiliser. According to one embodiment, the pH of the suspension 25 is adjusted by adding at least one reducing agent 14, such as, for example, hydrogen peroxide 14*, to the suspension 25 at the end of the dissolution of the manganese-containing material 11 in step 701 so that the pH value of the suspension 25 is raised to, for example, about pH = 3.5. More generally, at the end of the dissolution of the material 11, the pH of the suspension 25 is adjusted in step 701 to a value range of pH = 3 to 5, more specifically, to a value range of pH = 3 to 4. In this way, iron 27.2 can be removed from the suspension 25 into the same first precipitate 16 as was already formed in the suspension 25 during the dissolution step 402 of the manganese-con- taining material 11 in the presence of water 12, sulphuric acid 13 and at least one reducing agent 14. This also has the advantage that iron 27.2 can be removed with the chemical used in dissolving the manganese-cont aining material 11, i.e. with at least one reducing agent 14, such as, for example, hydrogen peroxide 14*, and no additional substances are required to remove iron 27.2. In addition, a further advantage is that the precipitate 16 formed here is relatively easy to separate from the suspension 25 due to its fineness without, for example, the risk of filter clogging, which has been found to be a problem when using, for example, sodium hydroxide for the same purpose. The development of hydrogen sulphide in such a pH range is also reduced in the subsequent sulphide precipitation in step 408. In addition to the removal of iron 27.2, increasing the pH of the suspension 25 also improves the quality of the end product 24, especially in fertiliser use. A pH value of the end product 24 that is closer to neutral is healthier for plants than a solution that is too acidic.

[0068] If the at least one reducing agent 14, such as, for example, hydrogen peroxide 14*, is not sufficient to raise the pH of the suspension 25 (for example, to precipitate iron) , a small amount of manganese slurry 11 ' , more generally, the manganese-contain- ing material 11 of zinc electrolysis, i.e. the raw material of the method according to the invention, can also be added to the suspension 25 in step 703. The need for this addition is seen by visual examination 702.2 of the sample filtered from the suspension 25 in step 702.1, performed in step 702. If in step 702.3 it is found that the dissolution has gone too far, so to speak, i.e. the suspension 25 contains a lot of excess peroxide 14 ' , the process solution 15 filtered from the suspension 25 bubbles, is yellowish and the pH practically no longer rises in a sensible manner. In this case, by adding manganese slurry 11 ' and possibly a small amount of acid 13 to the suspension 25 in step 703, the reaction to precipitate iron 27.2 into the first precipitate 16 can be reversed, if necessary. In this case, the excess peroxide 14 ' that has ended up into the suspension 25 is decomposed, which is what steps 702, 703 in question can also be called. Step 703 is only carried out if necessary. In this case, a small amount of additional acid and manganese dioxide that comes with the manganese slurry 11 ' helps to raise the pH of the suspension 25 as the acid, hydrogen peroxide 14* and manganese dioxide react with each other. Thus, the pH of the suspension 25 is adjusted during the precipitation of iron 27.2 by using one or more of the following: at least one reducing agent 14, such as, for example, hydrogen peroxide 14*, the manganese-cont aining material 11 and / or acid 13. The operations of step 403 can be carried out in the same reactor 31 as the actual dissolution, i.e. the formation of the sus- pension 25, was carried out.

[0069] Before the first precipitate 16 is separated from the suspension 25 in step 405, the suspension 25 can, according to one embodiment, additionally be pumped through a screen 45 in step 404 (Figures 3a and 3b) . This can be used to separate coarser material from the suspension 25, i.e. waste material from the method point of view, such as, for example, all kinds of stone and concrete materials and foreign objects. In addition, screening 45* can be used to separate any insoluble manganese granules and also anode chips from the suspension 25. Indeed, the pilot phase tests have shown that not all the manganese contained in the material 11 necessarily dissolves completely in the dissolution step 402 without a significant excess of chemicals. The bottom of the reactor 31 is left with coarse manganese-cont aining material granules, ranging in size from millimetres to ten millimetres and even more. These cause technical process problems in pipelines and pumps. For example, a wet screen 45' can be used as a screen 45.

[0070] Thus, according to one embodiment, the manganese sulphate component in suspension form may be passed from the reactor 31 through the wet screen 45' in step 404, whereby the coarse fraction insoluble in the dissolution step 402 is recovered as an overhead product from the screen 45 and the finely divided lead-silver precipitate 16, suspended in the process solution 15, in turn continues through the screen 45 to the fine filtration 32 to the frame filter 32 ' . According to one embodiment, the boundary between coarse and fine filtration can be, for example, in the range of 0.5 to 2.5 mm. The complete insolubility of the material 11 may be related, for example, to the fact that the material 11 possibly contains manganese in two or more oxidation number forms, some of which dissolve more easily and some less easily. Here, the more easily soluble oxidation number forms refer to oxidation number forms that are soluble at the main calculated chemical amounts (for example, 5 to 10% excesses are allowed) . Here, the oxidation number forms that are less easily soluble refer to those oxidation number forms that are also soluble, but require significant excess amounts of chemicals for achieving this, reducing the profitability of the process. This means up to several tenths of percent excess of the chemical content. Thus, according to one embodiment of the invention, the manganese-containing material 11 to be processed according to the invention can be characterised as containing manganese in two or more oxidation number forms. Furthermore, there are solubility differences between its different oxidation number forms. This is precisely what is assumed to be the case in the material 11 of zinc electrolysis. More generally, this feature can also be characterised, in terms of the method according to the invention, as including optimising the reductive acid treatment step with respect to the amount of one or more chemicals used therein. In this optimisation, the chemicals are used in a calculated amount based on the manganese content of the material 11. In this case, it is possible that at the end of the dissolution step, insoluble starting material still remains in the reactor 31, for example, due to the above-mentioned reason. It will not dissolve at the amount of chemical calculated on the basis of the manganese content of the material 11 and dosed into the reactor 31. Furthermore, in the absence of chemical overdosing, the insoluble material is characterised by being separated from the suspension 25 before its filtration 32.

[0071] According to one embodiment, the transfer of the coarser material fraction originating from the dissolution from the reactor 31 to the screening 45*, and also the screening 45* itself, can be carried out in a liquid-assisted dilution process. The dilution is achieved by recycling the suspension 25' , 25. Figure 3b shows one embodiment of the related apparatus implementation. It is located between the reactor 31 shown in Figure 3a, more generally the dissolution means 31 ' , and the filtration means 32, more generally the separation means 32* of the first precipitate 16. In Figure 3b, the suspension, including coarse material 64 to be screened out from it, is indicated by a reference number 25' . The suspension without coarse material 64 screened out from it, is, in turn, indicated by a reference number 25.

[0072] According to the embodiment, the reactor 31 is discharged for example as follows. When the dissolution of the material 11 is complete in the reactor 31, the recycling 63.1 of the suspension 25' in the reactor 31 is initiated from the lower part 61 of the reactor 31 back to the reactor 31, now to its upper part 62. In this case, the heavier coarse fraction 64 accumulated at the bottom of the reactor 31 is recycled through the bottom valve along the pipeline 65 back to the upper part 62 of the reactor 31. The pipeline 65 of the recycling 63.1 has a pipe branch 66 and a subsequent pipeline 67 to the screen 45 for screening 45* the coarse material 64 out of the suspension 25. After some time of the recycling 63.1, i.e. after mixing of the suspension 25 and the coarse material 64, the side branch 66 from the recycling line 63.1 to the screen 45 is opened. In this case, part of the suspension 25' and the accompanying coarse fraction 64 is returned to the reactor 31 and part goes to the screen 45. Thus, it can also be called as the feed to the screen 45 on the bypass principle. The coarse material 64 remains on the screen 45, from where it continues to the collection box 69. The suspension 25 containing lead-silver precipitate passes through the screen 45. The coarse-content suspension 25' is very challenging both in terms of its transfer and also in terms of its screening 45*. As already stated above, as a waste fraction originating from the zinc industry, it may contain, in addition to insoluble manganese granules, also stones, concrete and brick fragments and even possible foreign objects. More generally, it is solid and insoluble waste material from the point of view of the method according to the invention .

[0073] In the embodiment shown, the suspension 25 passing through the screen 45 can also be returned to the reactor 31 via the return line 68. Thus, this can also be referred to as a recirculation 63.2. In this case, the amount of liquid in the reactor 31 and also in the circuit 63.1 and also on the screen 45 remains sufficient at all times. This method, also called a dilution transfer, by recycling 63.1, 63.2 of the suspension 25' , 25 at one or more points after the reactor 31, either before and / or after the screen 45 back into the reactor 31, improves the removal of the coarse material 64 from the reactor 31, the problem-free flow of the coarse material-containing suspension 25' in the pipelines 65, 67, as well as the performance of the screening 45* itself. In other words, this enables a smoother mass flow to the screen 45 and also ensures better performance of the transfer of the suspension 25' .

[0074] Once most of the coarse fraction 64 has been removed by the screen 45, the flow of the suspension 25 from the screen 45 to the reactor 31 is cut off and diverted from the outlet side of the screen 45 to an intermediate container, into which the suspension 25 containing the lead-silver precipitate is led. The same is done for the bypass flow 63.1 arranged before the screen 45. The screening 45* is continued until the coarse fraction 64 is no longer discernible.

[0075] At the apparatus level, the liquid-assisted transfer of the suspension 25 out of the dissolution can be characterised in that the apparatus 10 includes the screening means 45 arranged between the dissolution means 31 ' and the first separation means 32* for separating the coarse fraction 64 insoluble in the dissolution means 31 ' from the suspension 25' . In addition, the apparatus 10 also includes dilution means 70 for diluting the suspension 25' before transferring the suspension 25' to the screening means 45.

[0076] The dilution means 70 in turn include transfer means 71.1,

[0077] 71.2, such as here pumps, with at least one recirculation 63.1,

[0078] 63.2. These are jointly adapted to transfer the suspension 25' from the dissolving means 31 ' to the screening means 45. This transfer line includes a bypass line 65 as a first recirculation 63.1 for recirculating at least part of the suspension 25' of the dissolving means 31 ' back to the dissolving means 31 ' . Furthermore, these are collectively adapted to return at least part of the suspension 25 from the screening means 45 to the dissolving means 31 ' via a return line 68 as a second recirculation 63.2.

[0079] After the screening 45*, the suspension 25 can be transferred, for example, by pumping, for example via the intermediate container, to the separation step of the first precipitate 16, which is carried out by filtration 32. According to one embodiment, this can be done, for example, with a frame filter 32 ' . In this case, the recovery of the lead-silver precipitate, i.e. the first precipitate 16 formed in the dissolution step, which according to the embodiment now presented includes also iron 27.2, is carried out. However, the first precipitate 16 is largely composed of lead sulphate and calcium sulphate. The first precipitate 16 can be supplied as a product component as an industrial raw material, for example, to a lead smelter, or for possible further processing and utilisation of the fractions separated from it. The manganese granules screened before separation of the first precipitate 16 can be ground and subsequently redissolved (not shown) . According to one embodiment, ultrasound can be used in the dissolution, for example, to enhance the dissolution of these manganese granules.

[0080] Returning to Figure 4, according to one embodiment of the method, the method may further include a sub-step 406 for adjusting the manganese oxidation number. According to one embodiment, after the separation of the first precipitate 16, i.e. step 405, but nevertheless before the second precipitation step 408 of the sulphide precipitate 23 using at least one sulphide source 19, the manganese oxidation number in the process solution 15 is changed / af f ected, more generally, is processed or even optimised, if necessary. This is done according to a first embodiment by adjusting the pH of the process solution 15 in step 406. The pH adjustment of the process solution 15, and thus the adjustment of the manganese oxidation number, changes the colour of the process solution 15 from yellow- ish / orangish back to pink. If the precipitation of iron 27.2 is carried out before this in step 403, it can then be called the first pH adjustment and if the influence on the manganese oxidation number is carried out in the same embodiment, it can then be called the second pH ad ustment. The step 406 may have its own reactor 40 after the filtration 32.

[0081] According to another embodiment, to change the colour of a yellowish or orangish solution to pink, i.e. to optimise the manganese oxidation number in the process solution 15, sodium sulphite 46 can be used as a chemical. Sodium sulphite is used to deoxygenate the various oxides of manganese in the process solution 15, causing manganese to return to its sulphate form and the process solution 15 to change its colour to the desired pink colour. Sodium sulphite 46 is used in solution form and dissolved in water. Since sodium may already be present in the process solution 15, and the excess sulphite is converted to sulphate in the final pH range of the process solution 15, the use of sodium sulphite 46 to change the manganese oxidation number to the desired one does not introduce additional components into the process solution 15.

[0082] In accordance with the flow diagram shown in Figure 8a, according to a first embodiment, step 406, i.e. affecting the manganese oxidation number after the separation step 405 of the first precipitate 16, may also be divided into several substeps 801 to 805, one possible combination of which is presented as an example below. According to an embodiment, the need to change the manganese oxidation number is determined based on the visual inspection of the process solution 15 performed in step 801. The manganese oxidation number is the desired one, i.e. Mn2+, when the process solution 15 is found to be pink in colour in step 802. Instead of that, if the process solution 15 is found in step 802 to be, for example, yellowish, orange or another non-pink colour (shades of green or purple) , the manganese oxidation number in the process solution 15 is incorrect (too high) and can then be changed (reduced) by pH adjustment in step 803a. If the manganese oxidation number in the process solution 15 is not at the desired level, solid manganese dioxide will begin to form at the bottom of the end product solution, i.e. the manganese sulphate solution 24, over time. In addition, some manganese hydroxides may also precipitate out of the solution 24, which will subsequently oxidise.

[0083] In addition to the determination of the manganese oxidation number of the process solution 15 by visual inspection in step 801 and its possible modification in a direction more favourable to the end product 24, this same sub-step 406 can also have a downward effect on the cadmium content of the process solution 15. The steps are performed in an ATEX-classif ied purification container 40, because hydrogen is generated in the method.

[0084] According to one embodiment, the manganese oxidation number in the process solution 15 is modified in step 803a by lowering the pH value of the process solution 15 from pH = 3.5 to the value range of pH = 1.5 to 2.5 by using sulphuric acid 13' . When the colour of the process solution 15 changes from orange / yellowish to pink, it can be concluded from the colour change observed in step 804 that the manganese oxidation number in the process solution 15 has changed as desired. Sulphuric acid 13' is a preferred chemical to use in this context, because the entire process is already based on it. Sulphuric acid 13' can be the same as that which was already used in the acid dissolution of the material 11.

[0085] After this, in step 805a, the pH of the process solution 15 is raised back to the value range of pH = 2.5 to 4.5, more specifically of pH = 2.5 to 4.5, using metallic zinc 28 in powder or granular form. Thus, with solid metallic zinc 28, the pH of the process solution 15 is restored to or close to its original value. The consumption of zinc 28 here can be, for example, about 1 to 5 grams, more specifically, 2 to 4 grams per litre of solution.

[0086] The partial dissolution of the solid metallic zinc 28 consumes then acid and as a result the pH of the process solution 15 rises again. As mentioned above, cadmium is also removed from the process solution 15 in this sub-step and it is based on the presence of metallic zinc 28 in the process solution 15, which according to one embodiment is used to raise the pH of the process solution. In this case, cadmium binds to the surface of metallic zinc 28. An alternative to metallic zinc 28 at this point may be, for example, metallic manganese.

[0087] As with other concentrations, in the method can also be determined the cadmium concentration of the process solution 15, if necessary. This can be done, for example, in the context of step 406, where a reduction of the cadmium content in the process solution 15 also occurs as a by-product. An example of a criterion value set for the cadmium concentration might be 200 mg / 1 kg of trace nutrient (in fertiliser) , i.e. approxi- mately 30 mg / 1 in a solution containing 150 g / 1 manganese. The determination of the cadmium content in the process solution 15, as well as all other metal content measurements in the process, can be performed, for example, with ICP-OES analysis apparatus .

[0088] Returning again to Figure 4, in the embodiment shown, the next step 407 after the pH adjustment steps 803a and 805a is the filtration of the mass solution 41, i.e. the separation of the second precipitate 29 in sequence from the process solution 15 (Figure 5) . This can be done, for example, with a separate frame filter 41 ' . The filtration is performed approximately 15 to 60 minutes after the start of step 805a, depending, for example, on how quickly the desired pH (> 3) (or cadmium content) was achieved.

[0089] The metallic zinc precipitate 29 obtained from the filtration in step 407, also including the cadmium 30.2 bound to zinc 28 ' from the solution 15 by the same pH adjustment process, can be further used, for example, as a raw material for the zinc industry. Now, the processing of the manganese oxidation number is proposed to take place before precipitation 103, 203, 408 using at least one sulphide source 19. On the other hand, it could take place also afterwards, i.e. after the sulphide precipitate 23 has been separated from the solution 15.

[0090] According to another embodiment, shown in Figure 8b, changing the manganese oxidation number in the process solution 15 may be accomplished using sodium sulphite 46. Steps 802 and 804 are performed as above. In step 803b, sodium sulphite 46 is added to the process solution 15. The amount to be added can be based on, for example, laboratory experiments. The pH of the process solution 15 may be approximately 3 before the addition. The addition of sodium sulphite 46 slightly increases the pH of the process solution 15 (approximately 3 -> 4) . After the sulphite addition, the pH of the process solution 15 can be lowered by adding sulphuric acid into it in step 805b. The pH of the process solution 15 is adjusted to a value range of pH = 3 to 4 with sulphuric acid. In this embodiment the separate filtration 407 according to the previous embodiment is not needed.

[0091] Next, in step 408, a sulphide precipitation is carried out. In this step, at least one sulphide-containing substance 19 is added to the process solution 15 as a reagent to precipitate metals and / or metal compounds from the process solution 15 as sulphide precipitation. The sulphide source 19 may be one or more of the following: sodium sulphide 19' , barium sulphide or hydrogen sulphide. Preferably, the sulphide source 19 is sodium sulphide 19' . Sodium sulphide 19' is in this context an easy chemical in terms of its solubility and also in terms of its feedability into the reactor 34. In step 408, the sulphide anion reacts with the soluble metal cations in the solution to form solid metal sulphides, which can then be separated from the solution 15 as a precipitate. In the precipitate 23 formed as a result of the precipitation in step 408, at least zinc 20, copper 21 and possible cadmium residues 30.1 precipitate from the process solution 15. Since sulphide precipitation affects the pH of the process solution 15, any iron residues 27.1 are also precipitated into the precipitate 23. Sodium sulphide 19' can be added to the process solution 15 as a solution. A gas scrubber is arranged in the reactor 34 to treat the gaseous hydrogen sulphide generated (not shown) .

[0092] In step 409, the precipitate 23, and now, in the embodiment shown, the third precipitate 23 in sequence, containing metal sulphides 22 is separated from the process solution 15. The solid sulphide precipitate 23 includes mostly zinc sulphide, but as mentioned above, possibly also other aforementioned metals as metal sulphides. This precipitate 23 can also be further utilised as raw material for industry, i.e. thus forming a product component in its own right.

[0093] In addition to sulphide precipitation, the precipitation of iron 27.2 from the process solution 15 to be as part of the second precipitate 23 can be carried out by a change in pH caused by the sulphide precipitation itself. Here, the pH of the process solution 15 changes naturally for the precipitation of iron 27 without additional chemicals, because the sulphide precipitation itself neutralises the process solution 15 to some extent. However, the precipitation of iron to be as part of the first precipitate 16 is the more advantageous way of removing iron from the end product, as it diversifies the possible uses of the process solution 15. In other words, during the preparation step of the manganese sulphate component 24, it is not yet known whether the final solution will be used as a fertiliser 24.1 or as an industrial raw material 24.2. Furthermore, in some cases, the removal of iron in sulphide precipitation is not always certain, possibly due to the incorrect iron oxidation number.

[0094] In accordance with the flow diagram shown in Figure 9, according to one embodiment, step 409, i.e. the separation of the sulphide precipitate 23 from the process solution 15, can also be divided into several sub-steps 901 to 903, one possible combination of which is presented as an example below.

[0095] In step 901, clarification of the solution 15 is carried out. In this step, solution 15 is settled by gravity so that fine grained heavy sulphide precipitate 23 settles at least at the lower part of the solution volume and most preferably at its bottom. The settling is preferably carried out in a conical container / thickener , whereby the precipitate 23 accumulates in the bottom cone and is more easily separable.

[0096] In step 902, the sulphide precipitate 23 is separated from the cont ainer / thickener . According to one embodiment, this can involve, for example, filtration. The sulphide precipitate 23 formed by sulphide precipitation 408 and separated from the process solution 15 in step 409 is suitable as such for use as a raw material 51 in the zinc industry 50. The sulphide precipitate 23 is mainly composed of zinc 20 as the equivalent of metal sulphide 22, which is the main raw material for the zinc production by electrolysis. The suitability as a raw material 51 for the zinc industry 50 is also partly enhanced by the fact that the sulphide precipitate 23 does not contain significant amounts of lead, silver and calcium in sulphate form, i.e. , the first precipitate 16. Their removal from the process solution 15 already in the first precipitate removal 102, 202, 403 improves the usability of the sulphide precipitate 23. In step 903, the solution layer in the upper part of the container is filtered with a suitable filtration apparatus 33. According to one embodiment, it may be, for example, a frame filter 33' .

[0097] The manganese sulphate solution 24 separated from the sulphide precipitate 23 in step 409 may be further diluted with water in step 410, for example to improve its frost resistance and / or to adjust the pH, if necessary. This can be done, for example, with sulphuric acid. Manganese-containing wash water from the filtration step 405 of the lead-silver precipitate 16 can also be used for the aqueous dilution. In this case, the amount of the final solution is preferably increased more than with pure water. The final solution 24 can be used as a fertiliser 24.1 in agriculture and / or as a manganese-containing raw material 24.2 for industry. The manganese content of the solution 24 can be, for example, 150 to 200 g / litre. The pH value of the final solution 24 for further processing / use can be in the range of pH = 3 to 4. This makes is suitable for both agricultural and industrial applications. In this case, as an industrial raw material 24.2, for example, the chemical consumption in the hydroxide precipitation of the solution is lower.

[0098] Figures 10 to 12 further illustrate some embodiments of the invention in the form of rough block diagrams. The figures show that different embodiments can be varied in several different ways, within the limits of the same inventive concept. Figure 10 shows a single embodiment of the method including the iron precipitation A shown in Figure 7, Figure 11 shows a single embodiment of the method including the manganese oxidation number processing B shown in Figure 8a, and Figure 12 shows a single embodiment of the method including the steps of the flow diagram shown in Figure 4, i.e. the iron precipitation A and also the manganese oxidation number processing B.

[0099] Figure 13 further shows another, simplified embodiment of an implementation of the method according to the invention. In the above method, there have been two precipitate separations 102 and 104, first for the sulphate precipitate 16 after the dissolution step 101 and then for the sulphide precipitate 23 after the sulphide precipitation step 103. However, according to another embodiment it could also be operated in such a way that the method has only one precipitate separation 102, 104. According to Figure 13, it would be only after the sulphide precipitation 103 or according to Figures la and 2a only after the dissolution 101 of the material 11. Thus, the method according to the invention can be said to include, in its basic form, at least one precipitate separation step.

[0100] However, the two precipitate separations 102, 104 described above, after the sulphide precipitation 103 and in addition also after the dissolution 101 of the material 11, i.e. before the sulphide precipitation 103, at least have the advantage that the first precipitate separation 102, carried out after the dissolution 101 of the material 11 but before the sulphide precipitation 103, removes the sulphate precipitate 16 containing lead, silver and calcium from the process, which can be directed as a separate component for further use. This precipitate 16 is simpler in composition than if the precipitate 23 formed in sulphide precipitation 103 were also mixed with it. On the other hand, the precipitate 23 formed in the sulphide precipitation 103 is also simpler in composition than if the sulphate precipitate 16 were also mixed with it.

[0101] In addition, the separation of the precipitate 16 before the sulphide precipitation 103 has a beneficial effect on the chemical consumption of the sulphide precipitation. In this case, the consumption of the sulphide source 19 in the sulphide precipitation is significantly lower, because the composition being processed lacks the solid-form sulphates, such as, for example, lead, silver and calcium, which were removed with the first precipitate 16. Another additional advantage is that the metal sulphides 22 containing precipitate 23 from the sulphide precipitation is more suitable as such as a raw material 51 for the zinc industry 50 than if the first sulphate precipitate 16 were also included. The precipitations used in the invention are simple to implement as process measures and can also be carried out with process chemicals that are less harmful than, for example, extractions.

[0102] In addition to the method, the invention also relates to an apparatus 10 for manufacturing a manganese sulphate component 24 from a manganese-cont aining material 11 of zinc electrolysis by reductive acid dissolution. The apparatus 10 includes dissolution means 31 ' for forming a suspension 25 from a manganese- containing material 11 of zinc electrolysis in the presence of water 12, sulphuric acid 13 and at least one reducing agent 14. In addition, the apparatus 10 includes first separation means 32* for separating at least one first precipitate 16 from the suspension 25. Furthermore, the apparatus 10 includes precipitation means 34 ' for precipitating metals and / or metal compounds from the process solution 15 using at least one sulphide source 19. The apparatus 10 also includes second separation means 33* for separating a second precipitate 23 containing metal sulphides 22 from the process solution 15, after which the manganese sulphate component 24 formed is suitable for use as such as a fertiliser 24.1 in agriculture or as an industrial raw material 24.2. The apparatus 10 can be operated in all its parts and operations at normal pressure and room temperature (no heating is required) , which makes it simple to implement in those respects. Since the dissolution process is highly exothermic and the solution is constantly warming up, the dissolution reactor 31 is, as mentioned above, equipped with cooling 37. Temperature control in the form of cooling 37 optimises the consumption of hydrogen peroxide 14*, at least at the beginning of the dissolution. In addition, subsequent temperature control improves the dissolution of the material 11. Thus, in one embodiment, the method according to the invention may include optimising the temperature of the dissolution process at the beginning of the dissolution so that the temperature is at the beginning of the dissolution below 40°C and even lower, such as, for example, below 38°C to optimise the consumption of hydrogen peroxide 14*. When added to a reactor 31 that is too hot, some of the hydrogen peroxide 14* may spontaneously decompose into water and oxygen. This causes excessive gas formation in the reactor 31 and significantly increases the consumption of hydrogen peroxide 14*. By optimising the temperature, the hydrogen peroxide 14* reaction can be fully directed to its actual purpose, i.e. the decomposition of manganese dioxide. In addition, the reactor 31 will not become too misty, when the gas evolution is initially more moderate. The consumption of hydrogen peroxide 14* in side reactions would also have an adverse effect on the consumption of other chemicals.

[0103] According to one embodiment, the apparatus 10 includes a prescreening 42 of the material 11 arranged prior to the reactor 31, i.e. the dissolution step. According to one embodiment, the pre-screening 42 can be implemented, for example, by means of a grid and / or screening mesh 42 ' equipped with vibration motors. The pre-screening 42 is adapted to remove from the manganese- containing material 11 originating from the electrolysis of zinc concentrate, particles that are undesirable for the process apparatus 10, such as, for example stones, concrete and / or possible plastic debris accompanying the material 11.

[0104] As is clear from the method description above, the apparatus 10 can also be implemented, for example, without any equipment for forming sulphide precipitate 23 and removing it from the process solution 15, whereby the end product 24 obtained from the dissolution method, including its ancillary steps, is suitable as such for use as a fertiliser in agriculture. However, a more preferred embodiment of the apparatus 10 is that shown in the figures. In this case, using the same single apparatus configuration and also the same process, it is possible, with very minor changes, to produce in the same process plant an end product for agricultural use, for example as a fertiliser (for example without sulphide precipitation) as well as for industrial needs (with sulphide precipitation) .

[0105] In addition to the method and apparatus 10, the invention also relates to a manganese sulphate component 24, which is formed from a manganese-cont aining material 11 of zinc electrolysis by means of a reductive acid treatment. In the reductive acid treatment, the material 11 is dissolved 101, 201, 402 in the presence of water 12, sulphuric acid 13 and at least one reducing agent 14 to form a suspension 25 of the manganese- containing material 11. A first precipitate 16 containing at least lead 17 and silver 18 is separated from the suspension 25. Metals and / or metal compounds, including one or more of the following: zinc 20, copper 21, are precipitated 103, 203, 408 from the process solution 15 using at least one sulphide source 19. A precipitate 23 containing metal sulphides 22 is separated 104, 204, 409 from the process solution 15, after which the formed manganese sulphate component 24 is suitable for use as such as a fertiliser 24.1 in agriculture or as an industrial raw material 24.2.

[0106] As already stated above, the process solution 15 obtained from the dissolution step as it is, i.e. without sulphide precipitation, would be suitable for use as such as a fertiliser 24.1 in agriculture. In this case, the invention can be defined, for example, as a method for preparing a manganese sulphate component 24 from manganese-cont aining material 11 of zinc electrolysis, wherein manganese-containing material 11 is dissolved 101, 201, 402 in the presence of water 12, sulphuric acid 13 and at least one reducing agent 14 to form a suspension 25, and then a process solution 15 is formed from the suspension 25 by separating 102, 202, 403 from it as a dissolution residue, after dissolution 101, 201, 402, a precipitate 16 containing at least lead 17 and silver 18. After this, the manganese sulphate component 24 formed of the process solution 15 is suitable for use as a fertiliser 24.1 at least in agriculture.

[0107] In addition, the invention also relates to the use of the manganese sulphate component 24 obtained by the method according to the invention. The manganese sulphate component 24 is used as a component in the manufacture of the end product 24.1, 24.2, which is selected from a fertiliser and, for example, a battery chemical.

[0108] The invention may also further relate to the use of the precipitate 23 containing metal sulphides 22, obtained by the method according to the invention, as a raw material component 51 in the zinc industry 50.

[0109] Another application still related to the invention is also the use of the solid dissolution residue of the manganese- containing material 11, i.e. lead-silver precipitate 16, as a component in the manufacture of another end product. The end product may include one or more of the metals present in the sulphate precipitate 16, i.e. lead and / or silver. In this case, the object of the invention may be, for example, the use of the precipitate 16 containing lead sulphate, which has been obtained by the method according to the invention, as a raw material component in the lead industry. In particular, the sulphate precipitate 16 in question is washed after the dissolution in which it was formed. In this case, its manganese content is non-existent, so that it does not interfere the further processing of the precipitate 16 in question.

[0110] Still further, the invention relates also to a product containing a manganese sulphate component obtained by the method according to the invention.

[0111] The raw material of the method according to the invention, i.e. the material originating from a secondary manganese source, is a manganese-cont aining material 11 originating from zinc electrolysis, for example in the form of a manganese slurry 11 ' . It includes mainly of oxidised manganese, i.e. solid manganese dioxide. Its manganese content may be, for example, 25 to 55% by weight, more particularly 30 to 50% by weight, even more particularly 35 to 50% by weight. The concentrations of metals in the manganese precipitate to be removed as impurities by the method may, in turn, be in the following value ranges: zinc 20 for example 1 to 15 wt-%, copper 21 for example 0.01 to 5 wt- %, cadmium 30, 30.1, 30.2 for example 0.01 to 5 wt-%, lead 17 for example 4 to 12 wt-%, more particularly 4 to 8 wt-%, silver 18 for example 0.01 to 5 wt-% and iron 27, 27.1, 27.2 for example 0.01 to 5 wt-% (of dry matter) . Another example of a manganese-cont aining material 11 could also be manganese dioxide separated from batteries. The method according to the invention does not produce any waste water. The water cycle of the process is closed. All wash waters and residues of previous solvents of the process can be recycled to the process.

[0112] It should be understood that the above description and the accompanying drawings are intended only to illustrate the present invention. The invention is therefore not limited to the embodiments presented above, but many different variations and modifications of the invention will be obvious to those skilled in the art, which are possible within the scope of the inventive concept defined by the appended Claims.

Claims

CLAIMS1. A method for manufacturing a manganese sulphate component from a manganese-cont aining material (11) of zinc electrolysis, wherein- a manganese-cont aining material (11) is dissolved (101, 201, 402) in the presence of water (12) , sulphuric acid (13) and at least one reducing agent (14) to form a suspension (25) ,- a process solution (15) is formed from the suspension (25) by separating (102, 202, 403) therefrom a first precipitate (16) including at least lead (17) and silver (18) ,- metals and / or metal compounds, including one or more of the following: zinc (20) , copper (21) , are precipitated (103, 203, 408) from the process solution (15) by using at least one sulphide source (19) ,- a precipitate (23) including metal sulphides (22) is separated (104, 204, 409) from the process solution (15) , after which the manganese sulphate component (24) formed is suitable for use as a fertiliser (24.1) in agriculture or as an industrial raw material (24.2) .

2. The method according to Claim 1, characterised in that the method further includes at least one step (403) in which iron (27.2, 27.1) is precipitated from the suspension (25) and / or from the process solution (15) to be as part of the first and / or second precipitate (16, 23) by adjusting the pH of the suspension (25) and / or the process solution (15) , and wherein the pH of the suspension (25) and / or the process solution (15) is adjusted (403, 701, 703) preferably using one or more of the following: at least one reducing agent (14) , such as, for example, hydrogen peroxide (14*) , and / or the manganese-containing material (11) of zinc electrolysis.

3. The method according to Claim 2, characterised in that iron (27.2) is precipitated (402) from the process solution (15) to be as part of the first precipitate (16) such that at the end of the dissolution (101, 201, 402) of the material (11) , the pH of the process solution (15) is adjusted (701, 704) to a value range of pH = 3 to 5, more particularly, to a value range of pH = 3 to 4.

4. The method according to Claim 2 or 3, characterised in that iron (27.1) is precipitated from the process solution (15) to be as part of the second precipitate (23) by sulphide precipitation (103, 203, 408) by affecting the pH of the process solution (15) .

5. The method according to any one of Claims 1 to 4, characterised in that the method includes changing (406) the manganese oxidation number in the process solution (15) , if necessary, the need for which is determined (802) based on visual inspection (801) of the process solution (15) .

6. The method according to any one of Claims 1 to 5, characterised in that the method includes changing (406) the manganese oxidation number in the process solution (15) , if necessary, by adjusting the pH (803a) of the process solution (15) .

7. The method according to Claim 6, characterised in that the manganese oxidation number in the process solution (15) is changed (406) by- lowering (803a) the pH of the process solution (15) to the value range of pH = 1.5 to 2.5 using sulphuric acid (13) ,- raising (805a) the pH of the process solution (15) to the value range of pH = 2.5 to 4.5 using zinc (28) .

8. The method according to Claim 7, characterised in that in addition to changing the manganese oxidation number, the pH adjustment (406) is used to reduce the cadmium content of the process solution (15) using said zinc (28) used to raise the pH of the process solution (15) .

9. The method according to Claim 5, characterised in that the manganese oxidation number in the process solution (15) is changed (406) using sodium sulphite (46) as the chemical.

10. The method of any one of Claims 1 to 9, characterised in that the sulphide source (19) is one or more of the following: sodium sulphide (19' ) , barium sulphide or hydrogen sulphide.

11. The method according to Claim 10, characterised in that the sulphide source (19) is sodium sulphide (19' ) .

12. The method according to any one of Claims 1 to 11, characterised in that the reducing agent (14) is one or more selected from the following: peroxide (14 ' ) , citric acid, one or more sugars .

13. The method according to any one of Claims 1 to 12, characterised in that the dissolution (101, 201, 402) of the manga- nese-cont aining material (11) is carried out by- forming (603) a suspension (25) by mixing the manganese- containing material (11) with water (12) ,- adding (605.1, 605.2) sulphuric acid (13) and at least one reducing agent (14) to the suspension (25) formed.

14. The method according to any one of Claims 1 to 13, characterised in that upon initiating the formation of the suspension (25) , sulphuric acid (13) is dosed (605.1) according to thecalculated amount of the lowest assumed manganese content of the manganese-containing material (11) .

15. The method according to any one of Claims 1 to 14, characterised in that upon initiating the formation of the suspension (25) ,- a sample (26) of the suspension (25) of the manganese- containing material (11) and water (12) is taken (604) for the determination of the manganese content (605. i) ,- the dissolution is initiated by dosing (605.1) sulphuric acid (13) into the suspension (25) to be processed according to the calculated amount of the lowest assumed manganese content of the manganese-containing material (11) ,- the exact manganese content of the dry matter fraction of the manganese-containing material (11) in a sample (26) taken from the suspension (25) , is determined (605. i) ,- the suspension (25) is finalised by dosing (607) water (12) , sulphuric acid (13) and at least one reducing agent (14) to it, based on the exact manganese content of the dry matter fraction of the manganese-containing material (11) determined.

16. The method according to any one of Claims 1 to 15, characterised in that the precipitate (23) including metal sulphides (22) is separated (407) from the process solution (15) by clarification (901) followed by filtration (902, 903) .

17. The method according to any one of Claims 1 to 16, characterised in that the pH of the process solution (15) before neutralisation is in the range of pH = 0 to 1.5.

18. The method according to any one of Claims 1 to 17, characterised in that the at least one reducing agent (14) , in the presence of which the manganese-containing material (11) isdissolved to form the suspension (25) , is hydrogen peroxide(14*) .

19. The method according to any one of Claims 1 to 18, characterised in that the manganese-cont aining material (11) of zinc electrolysis is manganese slurry (11' ) .

20. The method according to any one of Claims 1 to 19, characterised in that the first precipitate (16) is suitable for use as a raw material for the lead industry.

21. The method according to any one of Claims 1 to 20, characterised in that between the dissolution (101, 201, 402) of the manganese-cont aining material (11) and the separation (102, 202, 403) of the first precipitate (16) , there is a transfer of the suspension (25' ) to the screening (45*) and the subsequent screening (45*) of the suspension (25' ) , which are carried out at least part of the time by diluting the suspension (25' ) .

22. The method according to Claim 21, characterised in that the dilution of the suspension (25' ) is carried out by recycling (63.1, 63.2) of the suspension (25' , 25) , the recycling (63.1, 63.2) taking place before and / or after the screening (45*) of the suspension (25' ) .

23. The method according to any one of Claims 1 to 22, characterised in that the amount of the first precipitate (16) is 25 to 40% of the dry weight of the manganese-containing material (11) fed to the dissolution (101, 201, 402) .

24. The method according to any one of Claims 1 to 23, characterised in that peroxide (14 ' ) , more particularly hydrogen peroxide (14*) , is fed to the dissolution (101, 201, 402) below asurface of the suspension (25) to prevent premature decomposition of the peroxide (14 ' ) during the formation of the suspension (25) .

25. An apparatus for manufacturing a manganese sulphate component by reductive acid dissolution of a manganese-containing material (11) of zinc electrolysis, the apparatus (10) including- dissolution means (31 ' ) including at least one reactor (31) for forming a suspension (25' , 25) of manganese- containing material (11) in the presence of water (12) , sulphuric acid (13) and at least one reducing agent (14) ,- first separation means (32*) for separating a first precipitate (16) from the suspension (25) and for forming a process solution (15) ,- precipitation means (34 ' ) for precipitating metals and / or metal compounds from the process solution (15) using at least one sulphide source (19) ,- second separation means (33*) for separating a second precipitate (23) including metal sulphides (22) from the process solution (15) , after which the manganese sulphate component (24) formed is suitable for use as a fertiliser(24.1) in agriculture or as a raw material for industry(24.2) .

26. The apparatus according to Claim 25, characterised in that the apparatus (10) further includes- screening means (45) arranged between the dissolution means (31 ' ) and the first separation means (32*) for separating a coarse fraction (64) insoluble in the dissolution means (31 ' ) from the suspension (25' ) ,- dilution means (70) for diluting the suspension (25' ) before transferring the suspension (25' ) to the screening means (45) .

27. The apparatus according to Claim 26, characterised in that the dilution means (70) include transfer means (71.1, 71.2) with at least one recirculation (63.1, 63.2) adapted to achieve one or more of the following- to transfer the suspension (25 ' ) from the dissolution means (31 ' ) to the screening means (45) , wherein the recirculation (63.1) is adapted to form a bypass line (65) for recirculating at least a portion of the suspension (25' ) of the dissolution means (31 ' ) to the dissolution means (31 ' ) ,- to return at least a portion of the suspension (25) back as a second recycling (63.2) from the screening means (45) to the dissolution means (31 ' ) via a return line (68) .

28. A manganese sulphate component formed from a manganese- containing material (11) of zinc electrolysis by a reductive acid treatment, wherein- the manganese-cont aining material (11) is dissolved (101, 201, 402) in the presence of water (12) , sulphuric acid (13) and at least one reducing agent (14) to form a suspension (25) ,- a process solution (15) is formed from the suspension (25) by separating therefrom a first precipitate (16) containing at least lead (17) and silver (18) ,- metals and / or metal compounds including one or more of the following: zinc (20) , copper (21) , are precipitated (103, 203, 408) from the process solution (15) using at least one sulphide source (19) ,- a precipitate (23) including metal sulphides (22) is separated (104, 204, 409) from the process solution (15) , after which the manganese sulphate component (24) formed is suitable for use as a fertiliser (24.1) in agriculture or as an industrial raw material (24.2) .

29. Use of a manganese sulphate component, wherein the manganese sulphate component (24.1, 24.2) in aqueous solution form has been obtained by the method according to any one of Claims 1 to 24, as a component (24.1, 24.2) in the manufacture of an end product selected from a fertiliser and a battery chemical.

30. A product including a manganese sulphate component obtained by the method according to any one of Claims 1 to 24.

31. A method for manufacturing a manganese sulphate component from a manganese-cont aining material (11) of zinc electrolysis, wherein- a manganese-cont aining material (11) is dissolved (101, 201, 402) in the presence of water (12) , sulphuric acid (13) and at least one reducing agent (14) to form a suspension (25) ,- a process solution (15) is formed from the suspension (25) by separating (102, 202, 403) therefrom a precipitate (16) including at least lead (17) and silver (18) , after which the manganese sulphate component (24) formed by the process solution (15) is suitable for use as a fertiliser (24.1) , at least in agriculture.

32. Use of a precipitate including metal sulphides, obtained by the method according to any one of Claims 1 to 24, as a raw material component (51) in the zinc industry (50) .

33. Use of a precipitate including lead sulphate, obtained by the method according to any one of Claims 1 to 24, as a raw material component in the lead industry.

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