Method and application of dechlorination of titanium extraction tailings coupled with mineralization and storage of CO2 and co-production of NH4Cl

Abstract

The present invention discloses a method and application of titanium extraction tailings dechlorination coupled with mineralization and CO2 sequestration to produce NH4Cl. The titanium extraction tailings and hydrochloric acid are mixed and stirred to carry out a leaching reaction to obtain a first reactant; the first reactant is separated into solid and liquid to obtain a leachate and a leach residue, which can be used as a building material. After adding ammonia water to the leachate to adjust it to a predetermined pH value, carbon dioxide is introduced to carry out a mineralization reaction to obtain a second reactant; the second reactant is subjected to solid-liquid separation to obtain a separated liquid containing NH4Cl and solid residue (CaCO3 and MgCO3); the separated liquid is evaporated, concentrated, cooled and crystallized to obtain an NH4Cl product. The present invention can not only realize the recycling of valuable elements in titanium extraction tailings, but also reduce CO2 emissions to a certain extent, while co-producing building materials, CaCO3, MgCO3 and NH4Cl and other by-products, which is of great significance to promoting the green, low-carbon and sustainable development of the steel industry.

Description

Technical Field

[0001] The present invention relates to the technical field of the metallurgical industry, and in particular to a method and application of dechlorination of titanium extraction tailings coupled with mineralization and storage of CO2 and co-production of NH4Cl. Background Art

[0002] Titanium-extraction tailings are solid waste generated during the high-titanium blast furnace slag titanium extraction process, using a "high-temperature carbonization, low-temperature chlorination" process. They primarily contain elements such as Ca, Mg, Ti, Si, Al, C, and Cl. Effective utilization of these tailings is crucial for achieving a green and clean titanium-extraction process from high-titanium blast furnace slag. However, due to the high Cl ion content in these tailings, their application in building materials can severely corrode materials and reduce their service life. Therefore, it is imperative to explore economically viable ways to dechlorinate and recycle these tailings.

[0003] Patents CN201610830339.3 and CN201810167385.9 mix titanium-extracting tailings with a dechlorinating agent and then calcine and decarbonize them. The resulting low-chlorine titanium-extracting tailings are used as building materials. Patent CN201910188485.4 mixes titanium-extracting tailings with carbon-containing materials and granulates them. The tailings are then roasted to remove carbon and chlorine from the tailings and used as cement or concrete admixtures. Although the above processes can effectively reduce the chlorine content in the titanium-extracting tailings to meet the demand for building materials, the chlorine is discharged as hydrogen chloride or chlorine gas, which can easily cause environmental pollution and the chlorine is not fully utilized. Patent CN201811180048.X mixes titanium extraction tailings with water in a sealed container and then heats them to produce a titanium extraction tailings turbid liquid. After solid-liquid separation, drying, and grinding, slag powder is obtained for use in the preparation of building materials. Patent CN202211020361.3 adds water and a dechlorinating agent to the titanium extraction tailings to produce a tailings slurry. After separation in a hydrocyclone, underflow tailings slurry and overflow gypsum slurry are obtained. The overflow gypsum slurry is filtered to obtain gypsum. Both methods pose challenges in the disposal and resource utilization of chlorine-containing wastewater. Patent CN201210126531.6 crushes and separates the titanium extraction tailings, then leaches the coarse-grained titanium extraction tailings with hydrochloric acid, producing an aluminum dissolution solution after solid-liquid separation. The heated aluminum dissolution solution is then mixed with the fine-grained titanium extraction tailings, and after pH adjustment, temperature reduction, cooling, and filtration, polyaluminum chloride is obtained. While this process recovers Al and Cl from the titanium-extracting tailings, other valuable elements (Ca, Mg, Ti, Si, etc.) are not recycled. Therefore, efficiently and concisely realizing the resource utilization of titanium-extracting tailings is crucial for facilitating the large-scale treatment of high-titanium blast furnace slag using the "high-temperature carbonization, low-temperature chlorination" method and promoting the green, low-carbon, and sustainable development of the steel industry.

[0004] Based on this, the existing technology still needs to be improved. Summary of the Invention

[0005] To solve the above technical problems, the embodiments of the present invention propose a method and application of titanium extraction tailings dechlorination coupled with mineralization and storage of CO2 to co-produce NH4Cl, so as to solve the technical problems existing in the recycling of titanium extraction tailings in the prior art.

[0006] To solve the above technical problems, on the one hand, some embodiments of the present invention disclose a method for dechlorination of titanium extraction tailings coupled with mineralization and storage of CO2 and co-production of NH4Cl, comprising the following steps:

[0007] Step 1: mixing and stirring the titanium extraction tailings and hydrochloric acid to perform a leaching reaction to obtain a first reactant;

[0008] Step 2: separating the first reactant into solid and liquid to obtain leachate and leach residue;

[0009] Step 3: adding ammonia water to the leachate to adjust the pH to a predetermined value, and then introducing carbon dioxide to carry out a mineralization reaction to obtain a second reactant;

[0010] Step 4: performing solid-liquid separation on the second reactant to obtain a separated liquid and a solid residue;

[0011] Step 5: The separated liquid is evaporated, concentrated, cooled and crystallized to obtain NH4Cl product.

[0012] Furthermore, in step 1, the concentration of the added hydrochloric acid is 1-6 mol / L; the liquid-solid ratio of the hydrochloric acid to the titanium extraction tailings is (5-20):1.

[0013] Furthermore, in step 1, the reaction temperature of the leaching reaction is 30-90° C.; and the reaction time is 2-7 hours.

[0014] Furthermore, in step 2, the leached residue is dried and used as a raw material for building materials.

[0015] Furthermore, in step three, the predetermined pH value is 9-12.

[0016] Furthermore, in terms of weight percentage, the content of each element in the titanium extraction tailings is:

[0017] Ca 27.75%; Mg 8.71%; Al 9.18%; Si 11.98%; Ti 6.82%; C

[0018] 3.79%; O 25.06%; Cl 4.29%; others 2.42%.

[0019] Furthermore, the particle size of the titanium extraction tailings is 0.01 to 0.1 mm.

[0020] Furthermore, in the titanium extraction tailings, the elements exist in the following forms: CaO, MgO, TiO2, Al2O3, SiO2, TiC, CaCl2 and MgCl2.

[0021] Furthermore, the cooling crystallization temperature of the separated liquid is 0-30° C., and the time is 3-12 hours.

[0022] Furthermore, the drying temperature of the solid slag is 80-120°C.

[0023] On the other hand, some embodiments of the present invention further disclose a building material raw material prepared by the above method, which is obtained by drying the leached residue.

[0024] Some embodiments of the present invention further disclose a building material, comprising the above-mentioned building material raw materials.

[0025] By adopting the above technical solution, the present invention has at least the following beneficial effects:

[0026] The present invention provides a method and application of titanium extraction tailings dechlorination coupled with mineralization and CO2 storage and co-production of NH4Cl, which effectively recovers the chlorine element in the titanium extraction tailings. It can not only realize the recycling and utilization of valuable elements in the titanium extraction tailings, but also assist the large-scale process of "high-temperature carbonization and low-temperature chlorination" to treat high-titanium blast furnace slag, but also reduce CO2 emissions to a certain extent. At the same time, it co-produces building materials raw materials, CaCO3, MgCO3 and NH4Cl and other by-products, which is of great significance to promoting the green, low-carbon and sustainable development of the steel industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 This is a flow chart of a method for dechlorination of titanium extraction tailings coupled with mineralization and storage of CO2 and co-production of NH4Cl disclosed in some embodiments of the present invention. DETAILED DESCRIPTION

[0029] The following embodiments of the present disclosure are further described in detail with reference to the accompanying drawings and examples. The detailed description of the following examples and the accompanying drawings are intended to illustrate the principles of the present disclosure, but are not intended to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but rather includes all technical solutions within the scope of the claims.

[0030] The present disclosure provides these embodiments in order to make this disclosure thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values ​​set forth in these embodiments should be interpreted as merely exemplary, and not as limiting.

[0031] It should be noted that, in the description of this disclosure, unless otherwise specified, "plurality" means greater than or equal to two; terms such as "upper," "lower," "left," "right," "inner," and "outer" indicating directions or positional relationships are intended solely to facilitate and simplify the description of this disclosure, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this disclosure. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0032] In addition, the terms "first," "second," and similar terms used in this disclosure do not denote any order, quantity, or importance, but are merely used to distinguish different parts. "Perpendicular" does not mean perpendicular in the strict sense, but rather means within the tolerance range. "Parallel" does not mean parallel in the strict sense, but rather means within the tolerance range. "Include" or "comprising" and similar terms mean that the elements preceding the term include the elements listed after the term, and do not exclude the possibility of also including other elements.

[0033] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in this disclosure depending on the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intervening device between the specific device and the first or second device.

[0034] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined as such herein.

[0035] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0036] like Figure 1 As shown, some embodiments of the present invention disclose a method for dechlorination of titanium tailings coupled with mineralization and storage of CO2 and co-production of NH4Cl. The composition of the titanium tailings is shown in Table 1. The main components include elements such as Ca, Mg, Ti, Si, Al, C, and Cl, which exist in the form of CaO, MgO, TiO2, TiC, CaCl2, and MgCl2, respectively, and have a particle size of 0.01 to 0.1 mm.

[0037] Table 1 Chemical composition analysis of titanium tailings (wt.%)

[0038]

[0039] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: titanium extraction tailings and hydrochloric acid solution are mixed and stirred in a certain proportion to carry out a leaching reaction, and then the reactants are subjected to solid-liquid separation. In this process, the Ca, Mg, and Cl elements are leached by the hydrochloric acid to form a leachate containing Ca, Mg, and Cl ions, while the TiC, TiO2, SiO2, and part of the Al2O3 that do not react with the hydrochloric acid form a low-chlorine leachate residue, which can be used as a building material raw material after drying. Ammonia and CO2 are introduced into the leachate, and the pH value of the leachate is adjusted according to the amount of ammonia added. The solid residue obtained by solid-liquid separation is the mineralized products CaCO3 and MgCO3, and the separated liquid is evaporated, concentrated, and cooled and crystallized to obtain the NH4Cl product.

[0040] In the above process, the concentration of the hydrochloric acid solution is 1-6 mol / L, the liquid-solid ratio (hydrochloric acid: titanium extraction tailings) is 5-20:1, the leaching temperature is 30-90°C, the leaching time is 2-7h, the stirring method is magnetic stirring or mechanical stirring, the stirring rate is 600-1000r / min, the solid-liquid separation method is suction filtration, filter pressing or centrifugation, the leaching residue drying temperature is 80-120°C, the pH value of the leachate after adding ammonia water is 9-12, the solid slag drying temperature after mineralization is 80-120°C, the separation liquid cooling crystallization temperature is 0-30°C, and the time is 3-12h.

[0041] The method of coupling dechlorination of titanium tailings with mineralization and storage of CO2 and co-production of NH4Cl disclosed in the present invention, the hydrochloric acid concentration, liquid-solid ratio, leaching temperature and leaching time, stirring rate, etc. are mainly related to the leaching efficiency of Ca and Mg elements in the titanium tailings. Within a certain range, the higher the hydrochloric acid concentration, liquid-solid ratio, leaching temperature, leaching time, and stirring time, the higher the efficiency of leaching of Ca and Mg elements. The pH of the mineralization process is related to the mineralization efficiency. Within a certain range, the higher the pH, the more conducive it is to the reaction of CO2 with Ca and Mg ions. The cooling crystallization temperature and time are also mainly related to the crystallization efficiency. Within a certain range, the lower the temperature and the longer the time, the higher the crystallization efficiency.

[0042] Example 1

[0043] A method for titanium extraction tailings dechlorination coupled with mineralization and CO2 storage to produce NH4Cl, comprising the following steps:

[0044] (1) The titanium tailings and hydrochloric acid solution are mixed and stirred in a certain proportion to carry out a leaching reaction. The particle size of the titanium tailings is 0.05-0.1 mm, the concentration of the hydrochloric acid solution is 4 mol / L, the liquid-to-solid ratio of the mixed slurry is 10:1, the leaching temperature is 50°C, the leaching time is 5 h, and magnetic stirring is used at a stirring rate of 1000 r / min.

[0045] (2) performing solid-liquid separation on the reactant obtained in step (1) by suction filtration, and washing the reactant with deionized water 3 to 5 times to remove Ca, Mg, and Cl ions adsorbed on the surface of the leaching residue, thereby obtaining a leachate and a leaching residue, respectively;

[0046] (3) drying the low-chloride leaching residue obtained in step (2) at 110° C. for 12 h to obtain a raw material for preparing building materials;

[0047] (4) adding ammonia water to the leachate containing Ca, Mg, and Cl ions obtained in step (2) to adjust the pH to 10, then introducing CO2 to carry out a mineralization reaction, and then performing solid-liquid separation on the reaction product by suction filtration;

[0048] (5) drying the solid slag obtained in step (4) at 110° C. for 12 h to obtain mineralized products CaCO 3 and MgCO 3 ;

[0049] (6) The separated liquid obtained in step (4) is subjected to evaporation concentration and cooling crystallization to obtain NH4Cl product. The cooling crystallization temperature is 10°C and the time is 5 hours.

[0050] Example 2

[0051] A method for titanium extraction tailings dechlorination coupled with mineralization and CO2 storage to produce NH4Cl, comprising the following steps:

[0052] (1) The titanium tailings and hydrochloric acid solution are mixed and stirred in a certain proportion to carry out a leaching reaction. The particle size of the titanium tailings is 0.05-0.1 mm, the concentration of the hydrochloric acid solution is 1 mol / L, the liquid-to-solid ratio of the mixed slurry is 20:1, the leaching temperature is 90°C, the leaching time is 7 h, and magnetic stirring is used at a stirring rate of 800 r / min.

[0053] (2) performing solid-liquid separation on the reactant obtained in step (1) by filter pressing, washing the reactant with deionized water 3 to 5 times to remove Ca, Mg, and Cl ions adsorbed on the surface of the leaching residue, and obtaining a leachate and a leaching residue, respectively;

[0054] (3) drying the low-chloride leaching residue obtained in step (2) at 120° C. for 8 h to obtain a raw material for preparing building materials;

[0055] (4) adding ammonia water to the leachate containing Ca, Mg, and Cl ions obtained in step (2) to adjust the pH to 12, then introducing CO2 to carry out a mineralization reaction, and then performing solid-liquid separation on the reaction product by filter pressing;

[0056] (5) drying the solid slag obtained in step (4) at 120° C. for 8 h to obtain mineralized products CaCO 3 and MgCO 3 ;

[0057] (6) The separated liquid obtained in step (4) is subjected to evaporation concentration and cooling crystallization to obtain NH4Cl product. The cooling crystallization temperature is 0°C and the time is 3 hours.

[0058] Example 3

[0059] A method for titanium extraction tailings dechlorination coupled with mineralization and CO2 storage to produce NH4Cl, comprising the following steps:

[0060] (1) The titanium tailings and hydrochloric acid solution are mixed and stirred in a certain proportion to carry out a leaching reaction. The particle size of the titanium tailings is 0.01-0.05 mm, the concentration of the hydrochloric acid solution is 6 mol / L, the liquid-to-solid ratio of the mixed slurry is 5:1, the leaching temperature is 30°C, the leaching time is 5 h, and mechanical stirring is used at a stirring rate of 600 r / min.

[0061] (2) performing solid-liquid separation on the reactant obtained in step (1) by suction filtration, and washing the reactant with deionized water 3 to 5 times to remove Ca, Mg, and Cl ions adsorbed on the surface of the leaching residue, thereby obtaining a leachate and a leaching residue, respectively;

[0062] (3) drying the low-chloride leaching residue obtained in step (2) at 80° C. for 24 hours to obtain a raw material for preparing building materials;

[0063] (4) adding ammonia water to the leachate containing Ca, Mg, and Cl ions obtained in step (2) to adjust the pH to 11, then introducing CO2 to carry out a mineralization reaction, and then performing solid-liquid separation on the reaction product by suction filtration;

[0064] (5) drying the solid slag obtained in step (4) at 80° C. for 24 h to obtain mineralized products CaCO 3 and MgCO 3 ;

[0065] (6) The separated liquid obtained in step (4) is subjected to evaporation concentration and cooling crystallization to obtain NH4Cl product. The cooling crystallization temperature is 30°C and the time is 12 hours.

[0066] Example 4

[0067] A method for titanium extraction tailings dechlorination coupled with mineralization and CO2 storage to produce NH4Cl, comprising the following steps:

[0068] (1) The titanium tailings and hydrochloric acid solution are mixed and stirred in a certain proportion to carry out a leaching reaction. The particle size of the titanium tailings is 0.01-0.05 mm, the concentration of the hydrochloric acid solution is 3 mol / L, the liquid-to-solid ratio of the mixed slurry is 8:1, the leaching temperature is 70°C, the leaching time is 3 h, and mechanical stirring is used at a stirring rate of 1000 r / min.

[0069] (2) performing solid-liquid separation on the reactant obtained in step (1) by centrifugation, and washing the reactant with deionized water 3 to 5 times to remove Ca, Mg, and Cl ions adsorbed on the surface of the leaching residue, thereby obtaining a leachate and a leaching residue, respectively;

[0070] (3) drying the low-chloride leaching residue obtained in step (2) at 105° C. for 12 h to obtain a raw material for preparing building materials;

[0071] (4) adding ammonia water to the leachate containing Ca, Mg, and Cl ions obtained in step (2) to adjust the pH to 9, then introducing CO2 to carry out a mineralization reaction, and then separating the reaction product into solid and liquid by centrifugation;

[0072] (5) drying the solid slag obtained in step (4) at 105° C. for 12 h to obtain mineralized products CaCO 3 and MgCO 3 ;

[0073] (6) The separated liquid obtained in step (4) is subjected to evaporation concentration and cooling crystallization to obtain NH4Cl product. The cooling crystallization temperature is 20°C and the time is 8 hours.

[0074] Thus far, various embodiments of the present disclosure have been described in detail. To avoid obscuring the concept of the present disclosure, some details known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0075] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art will understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced with equivalents without departing from the scope and spirit of the present disclosure. In particular, as long as there are no structural conflicts, the various technical features mentioned in the various embodiments may be combined in any manner.

Claims

1. A method for dechlorination of titanium extraction tailings coupled with mineralization and storage of CO2 and co-production of NH4Cl, characterized in that: The following steps are involved: Step 1: mixing and stirring the titanium extraction tailings and hydrochloric acid to perform a leaching reaction to obtain a first reactant; Step 2: separating the first reactant into solid and liquid to obtain leachate and leach residue; Step 3: adding ammonia water to the leachate to adjust the pH to a predetermined value, and then introducing carbon dioxide to carry out a mineralization reaction to obtain a second reactant; Step 4: performing solid-liquid separation on the second reactant to obtain a separated liquid and a solid residue; Step 5: The separated liquid is evaporated, concentrated, cooled and crystallized to obtain the NH4Cl product; in step 1, the concentration of the added hydrochloric acid is 1-6 mol / L; the liquid-solid ratio of the hydrochloric acid to the titanium extraction tailings is (5-20):1, the reaction temperature of the leaching reaction is 30-90°C; and the reaction time is 2-7 hours; In step 3, the predetermined pH value is 9-12.

2. The method according to claim 1, characterized in that In step 2, the leached residue is dried and used as a building material raw material.

3. The method according to claim 1, characterized in that The particle size of the titanium extraction tailings is 0.01-0.1 mm.

4. The method according to claim 1, wherein The cooling crystallization temperature of the separated liquid is 0-30° C., and the time is 3-12 hours.

5. The method according to claim 1, wherein The drying temperature of the solid slag is 80-120°C.

6. A building material prepared by the method according to any one of claims 1 to 5, characterized in that: Obtained by drying the leaching residue.

7. A building material, characterized in that: Including the building material raw material according to claim 6.

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