Method for deep purification of barite by medium temperature activation and stepwise acid-base leaching

Abstract

The present application relates to a kind of methods for deep purification of barite by medium-temperature activation-stepwise acid-base leaching, belonging to the technical field of mineral processing and high-purity mineral material preparation.For the technical bottleneck that silicon, aluminum and iron impurities in barite concentrate are difficult to remove deeply because they exist in stable aluminosilicate lattice and quartz structure, the present application designs a stepwise sequential purification process of "medium-temperature activation roasting→gradient acid leaching to remove iron and aluminum→gradient alkali leaching to deeply remove silicon and aluminum" based on the thermal decomposition mechanism of aluminosilicate.Through the synergistic mechanism of "lattice thermal activation-stepwise leaching", deep removal of silicon, aluminum and iron impurities in barite is achieved.The obtained barium sulfate product has a purity of ≥99.5%, Fe<50ppmw and Al<50ppmw, and can be used in high-value-added fields such as photovoltaic glass, high-end coatings and electronic packaging materials.

Description

Technical Field

[0001] This invention relates to a method for deep purification of barite through medium-temperature activation and stepwise acid-base leaching, belonging to the field of mineral processing and high-purity mineral material preparation technology. Background Technology

[0002] Barite (mainly composed of BaSO4) is a key mineral raw material for the preparation of high-purity barium sulfate. Natural barite ore is generally closely associated with gangue minerals such as quartz, kaolinite, and calcite. Flotation is the main technique for separating barite, which can achieve preliminary separation of barite from minerals such as fluorite, calcite, and quartz, obtaining barite concentrate with a BaSO4 content of approximately 85-92%. However, flotation mainly acts on the surface-exposed mineral phases, and its separation capability is extremely limited for aluminosilicate impurities that exist in the barite matrix in the form of fine-grained embeddings or isomorphous structures.

[0003] In recent years, researchers have begun to explore chemical purification methods, but existing chemical methods have the following significant limitations: (1) Single acid leaching is insufficient for removing silicon and aluminum impurities. Although leaching barite flotation concentrate with sulfuric acid or hydrochloric acid can reduce the iron content to a low level, the removal rate of SiO2 and Al2O3 is limited, and the final purity of BaSO4 is difficult to exceed 98%. The fundamental reason is that the stable aluminosilicate mineral lattice (Si-O-Al bond) and quartz structure (Si-O-Si three-dimensional network) are difficult to be effectively destroyed by inorganic acids under normal temperature and pressure.

[0004] (2) The "alkali-then-acid" route has a colloidal contamination mechanism. If barite concentrate containing iron and aluminum impurities is directly leached with alkali, the silicate ions (SiO3) released by the dissolution of aluminosilicates will be affected. 2- It will react with Fe in the solution 3+ Al 3+ Rapid complexation and polymerization reactions occur, generating complex iron silicate and aluminum colloidal precipitates that densely coat the surface of barite particles, forming a dual physical and chemical barrier that severely hinders the mass transfer process. This leads to a significant decrease in the efficiency of subsequent washing or acid treatment, making the "alkali-first, acid-later" route difficult to apply industrially.

[0005] (3) Existing high-temperature roasting-acid leaching whitening technology has failed to solve the fundamental problem of deep purification. The patent application document with application number 201610938739.6 discloses that borax and NaOH are used as additives to roast at a high temperature of 1000~1100℃ and then acid leaching. Although whitening can be achieved, it has the following limitations: the roasting temperature is too high (1000~1100℃), resulting in high energy consumption; the addition of borax introduces exogenous B element, increasing the burden of subsequent separation; the whitening mechanism is based on the surface chemical effect of complex salt formation, and is not designed from the perspective of aluminosilicate lattice structure activation; the product uses whiteness as the main indicator, and no systematic technical solution has been established for the deep removal of key impurities such as Fe, Al, and Si; the lack of an alkaline leaching process results in incomplete removal of aluminum impurities released after aluminosilicate decomposition.

[0006] In summary, the core technical bottleneck of existing technologies in the deep purification of barite is: how to activate the aluminosilicate lattice with low energy consumption without introducing exogenous impurities, and how to avoid the generation of harmful byproducts through a precisely designed reaction sequence, so as to ultimately achieve the deep and synergistic removal of Fe and Al impurities. Summary of the Invention

[0007] To address the technical bottleneck of difficult deep removal of silicon, aluminum, and iron impurities from barite concentrate due to their presence in stable aluminosilicate lattices and quartz structures, this invention proposes a method for deep purification of barite through medium-temperature activation and graded acid-base leaching. Based on the thermal decomposition mechanism of aluminosilicates, a graded sequential synergistic purification process is designed, consisting of "medium-temperature activation roasting → gradient acid leaching for iron and aluminum removal → gradient alkaline leaching for deep removal of silicon and aluminum." Through the synergistic mechanism of "lattice thermal activation-graded leaching," deep removal of silicon, aluminum, and iron impurities from barite is achieved. The resulting barium sulfate product has a purity ≥99.5%, with Fe <50ppmw and Al <50ppmw, and can be used in high-value-added fields such as photovoltaic glass, high-end coatings, and electronic packaging materials.

[0008] A method for deep purification of barite through medium-temperature activation and stepwise acid-base leaching, the specific steps of which are as follows: (1) The barite concentrate is crushed and ground to a particle size of less than 200 mesh to obtain barite concentrate powder; (2) Barite concentrate powder is activated and roasted at a temperature of 550~750℃ in air atmosphere for 1~4h to thermally break the Si-O-Al bonds of aluminosilicate impurities in barite, and deaggregate and activate the aluminosilicate lattice to obtain activated roasted sand. (3) Activated calcined sand is added to an acid solution with a concentration of 10.0~20.0wt%, and leached by stirring at a temperature of 25~65℃ for 1~3h; then acid is added to adjust the acid concentration in the system to 20.0~36.0wt%, and leached by stirring at a temperature of 65~95℃ for 1~3h. Solid-liquid separation is performed to obtain a stepped acid leaching residue; the Fe content in the stepped acid leaching residue can be reduced to below 50ppmw, and the Al content can be reduced to below 920ppmw; the Al and Si residues in the stepped acid leaching residue are combined or exist in the aluminosilicate residue structure. (4) The graded acid leaching residue is added to a sodium hydroxide solution with a concentration of 7.4~20.0wt%, and leached by stirring at a temperature of 25~60℃ for 1~3h; then sodium hydroxide is added to adjust the sodium hydroxide concentration in the system to 20.0~30.0wt%, and leached by stirring at a temperature of 60~95℃ for 3~4h, and the solid and liquid are separated to obtain the graded alkaline leaching residue; (5) The leaching residue from the tiered alkaline process is washed with deionized water until neutral and then dried to obtain high-purity barium sulfate product.

[0009] In step (1), the barite concentrate contains not less than 85 wt.% barium sulfate, 400-900 ppmw iron, and 1000-1700 ppmw aluminum. The main impurities in the barite concentrate are silicon, aluminum, and iron in the form of aluminosilicates, quartz, and oxides.

[0010] Preferably, in step (3), the liquid-solid ratio of the acid solution to the activated calcined sand is 3~8:1 (mL:g).

[0011] Preferably, the acid solution is a sulfuric acid solution or a hydrochloric acid solution.

[0012] Preferably, in step (4), the liquid-to-solid ratio of sodium hydroxide solution to graded acid leaching residue is 3~15:1 (mL:g).

[0013] In step (5), the high-purity barium sulfate product contains no less than 99.5% barium sulfate, no more than 50 ppmw iron, and no more than 50 ppmw aluminum.

[0014] This invention relates to a method for deep purification of barite through medium-temperature activation and step-by-step acid-base leaching: (1) Medium-temperature activation of aluminosilicate: Al in barite concentrate is mainly hosted in the aluminosilicate phase, forming a stable three-dimensional network structure with Si-O-Al bonds; under medium-temperature calcination conditions of 550~750℃, the heat energy is sufficient to cause the Si-O-Al bonds to break thermally, thereby realizing the deagglomeration and structural activation of the aluminosilicate lattice, which causes the aluminosilicate skeleton to deagglomerate, creating structural conditions for subsequent chemical leaching. (2) Selective separation of Fe and Al in acid leaching: In the roasted sand material after calcination and activation, Fe exists in the form of Fe2O3, which has excellent solubility in the stepped acid system; Al2O3 released after the depolymerization of aluminosilicate can also be dissolved by the stepped acid. By optimizing the sulfuric acid concentration and leaching temperature, the preferential removal of Fe and the partial removal of Al can be achieved. (3) Alkaline leaching for deep removal of Si and Al: After acid leaching, although most of Fe and some Al have been dissolved, the remaining Al is mainly found in two forms that are difficult to be further acted upon by acid: one is the aluminosilicate residual phase that remains after roasting-acid leaching and is closely coexisting with quartz (SiO2); the other is the Al2O3 microparticles wrapped by dense quartz particles. If acid leaching is relied upon alone, it is impossible to break through the physical encapsulation and chemical inert barrier of the quartz structure. Based on the significant differences in the solubility characteristics of different minerals in alkaline media, this invention introduces an alkaline leaching step, so that Al2O3 and the aluminosilicate residual phase react in NaOH solution to generate soluble sodium aluminate, and quartz-type SiO2 is simultaneously dissolved and removed under alkaline leaching conditions.

[0015] The beneficial effects of this invention are: (1) The technical solution of the present invention is additive-free, medium-temperature activated, clean and efficient: no activator or calcination aid is required, which avoids the introduction of exogenous impurities and subsequent separation burden. The calcination temperature (550~750℃) is low and the energy consumption is significantly reduced. The atmospheric pressure air atmosphere reduces equipment investment and operation requirements. (2) The present invention features a tiered synergistic purification process: Based on a systematic study of the thermal decomposition behavior of aluminosilicates and the differences in the solubility of Fe / Al in acid / alkali systems, a synergistic process with strict sequential logic of "medium-temperature activation roasting → tiered acid leaching → tiered alkali leaching dealuminization" is designed; there is a clear scientific progressive relationship between each process, namely roasting and activating aluminosilicates → tiered acid leaching to remove Fe and part of Al → tiered alkali leaching to remove Si and Al, and the process logic is rigorous; (3) The present invention achieves deep removal of impurities to prepare high-purity products: Through the synergistic mechanism of “lattice thermal activation-sequential step leaching”, the targeted deep removal of Fe and Al impurities is achieved, the total removal rate of Al is ≥97%, the Fe content is reduced to below 50ppmw, and the product purity is significantly better than that of single acid leaching or “alkali first and acid later” route. (4) The barium sulfate content in the high-purity barium sulfate product of the present invention is not less than 99.5%, the iron content is less than 50 ppmw, and the aluminum content is less than 50 ppmw. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0017] Example 1: In this example, the barite concentrate contains no less than 85 wt.% barium sulfate, 400 ppmw iron, and 1700 ppmw aluminum. The main impurities in the barite concentrate are silicon, aluminum, and iron in the form of aluminosilicates, quartz, and oxides. A method for deep purification of barite through medium-temperature activation and stepwise acid-base leaching, the specific steps of which are as follows: (1) The barite concentrate is crushed and ground to a particle size of less than 200 mesh to obtain barite concentrate powder; (2) Barite concentrate powder is activated and roasted at 550℃ in air atmosphere for 1 hour to thermally break the Si-O-Al bonds of aluminosilicate impurities in barite, and deagglomerate and activate the aluminosilicate lattice to obtain activated roasted sand. (3) Activated calcined sand is added to a sulfuric acid solution with a concentration of 10.0 wt%, and the liquid-solid ratio of the sulfuric acid solution to the activated calcined sand is 3:1 mL:g; the mixture is stirred and leached at 25°C for 3 h; sulfuric acid is then added to adjust the sulfuric acid concentration in the system to 20.0 wt%, and the mixture is stirred and leached at 65°C for 3 h. Solid-liquid separation is performed to obtain a stepped acid leaching residue; the Fe content in the stepped acid leaching residue is reduced to 49 ppmw, and the Al content is reduced to 920 ppmw; the Al and Si residues in the stepped acid leaching residue are combined or exist in the aluminosilicate residue structure. (4) The graded acid leaching residue is added to a sodium hydroxide solution with a concentration of 7.4 wt%, wherein the liquid-solid ratio of the sodium hydroxide solution to the graded acid leaching residue is 3:1 mL:g; the residue is stirred and leached for 3 h at a temperature of 25 °C; sodium hydroxide is then added to adjust the sodium hydroxide concentration in the system to 20.0 wt%, and the residue is stirred and leached for 3 h at a temperature of 60 °C. Solid-liquid separation is then performed to obtain graded alkaline leaching residue. (5) The cascade alkaline leaching residue is washed with deionized water until neutral and dried to obtain high-purity barium sulfate product; In this embodiment, the high-purity barium sulfate product contains 99.5 wt% barium sulfate, 49 ppmw iron, and 30 ppmw aluminum.

[0018] Example 2: In this example, the barite concentrate contains no less than 85 wt.% barium sulfate, 400 ppmw iron, and 1700 ppmw aluminum. The main impurities in the barite concentrate are silicon, aluminum, and iron in the form of aluminosilicates, quartz, and oxides. A method for deep purification of barite through medium-temperature activation and stepwise acid-base leaching, the specific steps of which are as follows: (1) The barite concentrate is crushed and ground to a particle size of less than 200 mesh to obtain barite concentrate powder; (2) Barite concentrate powder is activated and roasted at 650℃ in air atmosphere for 2.5h to thermally break the Si-O-Al bonds of aluminosilicate impurities in barite, and deagglomerate and activate the aluminosilicate lattice to obtain activated roasted sand. (3) Activated calcined sand is added to a sulfuric acid solution with a concentration of 15.0 wt%, wherein the liquid-solid ratio of the sulfuric acid solution to the activated calcined sand is 5:1 mL:g, and the mixture is stirred and leached at 45°C for 2 h; then sulfuric acid is added to adjust the sulfuric acid concentration in the system to 28.0 wt%, and the mixture is stirred and leached at 80°C for 2 h, and the solid and liquid are separated to obtain a stepped acid leaching residue; the Fe content in the stepped acid leaching residue is reduced to 48 ppmw, and the Al content is reduced to 900 ppmw; the Al and Si residues in the stepped acid leaching residue are combined or exist in the aluminosilicate residue structure; (4) The graded acid leaching residue is added to a sodium hydroxide solution with a concentration of 20.0 wt%, wherein the liquid-solid ratio of the sodium hydroxide solution to the graded acid leaching residue is 9:1 mL:g; the residue is stirred and leached at 45°C for 2 hours; sodium hydroxide is then added to adjust the sodium hydroxide concentration in the system to 25.0 wt%, and the residue is stirred and leached at 80°C for 3.5 hours. Solid-liquid separation is then performed to obtain the graded alkaline leaching residue. (5) The cascade alkaline leaching residue is washed with deionized water until neutral and dried to obtain high-purity barium sulfate product; In this embodiment, the high-purity barium sulfate product contains 99.6 wt% barium sulfate, 48 ppmw iron, and 40 ppmw aluminum.

[0019] Example 3: In this example, the barite concentrate contains no less than 85 wt.% barium sulfate, 400 ppmw iron, and 1700 ppmw aluminum. The main impurities in the barite concentrate are silicon, aluminum, and iron in the form of aluminosilicates, quartz, and oxides. A method for deep purification of barite through medium-temperature activation and stepwise acid-base leaching, the specific steps of which are as follows: (1) The barite concentrate is crushed and ground to a particle size of less than 200 mesh to obtain barite concentrate powder; (2) Barite concentrate powder is activated and roasted at 750℃ in air atmosphere for 4 hours to thermally break the Si-O-Al bonds of aluminosilicate impurities in barite, and to depolymerize and activate the aluminosilicate lattice to obtain activated roasted sand. (3) Activated calcined sand is added to a sulfuric acid solution with a concentration of 20.0 wt%, wherein the liquid-solid ratio of the sulfuric acid solution to the activated calcined sand is 8:1 mL:g; the mixture is stirred and leached at 65°C for 1 h; sulfuric acid is then added to adjust the sulfuric acid concentration in the system to 36.0 wt%, and the mixture is stirred and leached at 95°C for 1 h. Solid-liquid separation is performed to obtain a stepped acid leaching residue; the Fe content in the stepped acid leaching residue is reduced to 42 ppmw, and the Al content is reduced to 820 ppmw; the Al and Si residues in the stepped acid leaching residue are combined or exist in the aluminosilicate residue structure. (4) The graded acid leaching residue is added to a sodium hydroxide solution with a concentration of 20.0 wt%, wherein the liquid-solid ratio of the sodium hydroxide solution to the graded acid leaching residue is 15:1 mL:g; the residue is stirred and leached at 60°C for 1 h; sodium hydroxide is then added to adjust the sodium hydroxide concentration in the system to 30.0 wt%, and the residue is stirred and leached at 95°C for 3 h. Solid-liquid separation is then performed to obtain the graded alkaline leaching residue. (5) The cascade alkaline leaching residue is washed with deionized water until neutral and dried to obtain high-purity barium sulfate product; In this embodiment, the high-purity barium sulfate product contains 99.8 wt% barium sulfate, 42 ppmw iron, and 45 ppmw aluminum.

[0020] Example 4: In this example, the barite concentrate contains no less than 85 wt.% barium sulfate, 400 ppmw iron, and 1700 ppmw aluminum. The main impurities in the barite concentrate are silicon, aluminum, and iron in the form of aluminosilicates, quartz, and oxides. A method for deep purification of barite through medium-temperature activation and stepwise acid-base leaching, the specific steps of which are as follows: (1) The barite concentrate is crushed and ground to a particle size of less than 200 mesh to obtain barite concentrate powder; (2) Barite concentrate powder is activated and roasted at 700℃ in air atmosphere for 3 hours to thermally break the Si-O-Al bonds of aluminosilicate impurities in barite, and to depolymerize and activate the aluminosilicate lattice to obtain activated roasted sand. (3) Activated calcined sand is added to a sulfuric acid solution with a concentration of 15.0 wt%, wherein the liquid-solid ratio of the sulfuric acid solution to the activated calcined sand is 6:1 mL:g; the mixture is stirred and leached at 45°C for 2 hours; sulfuric acid is then added to adjust the sulfuric acid concentration in the system to 28.0 wt%, and the mixture is stirred and leached at 80°C for 2 hours. Solid-liquid separation is performed to obtain a stepped acid leaching residue; the Fe content in the stepped acid leaching residue is reduced to 45 ppmw, and the Al content is reduced to 860 ppmw; the Al and Si residues in the stepped acid leaching residue are combined or exist in the aluminosilicate residue structure. (4) The graded acid leaching residue is added to a sodium hydroxide solution with a concentration of 14.0 wt%, wherein the liquid-solid ratio of the sodium hydroxide solution to the graded acid leaching residue is 10:1 mL:g; the residue is stirred and leached at 45°C for 2 hours; sodium hydroxide is then added to adjust the sodium hydroxide concentration in the system to 25.0 wt%, and the residue is stirred and leached at 80°C for 3.5 hours. Solid-liquid separation is then performed to obtain graded alkaline leaching residue. (5) The cascade alkaline leaching residue is washed with deionized water until neutral and dried to obtain high-purity barium sulfate product; In this embodiment, the high-purity barium sulfate product contains 99.7 wt% barium sulfate, 45 ppmw iron, and 38 ppmw aluminum.

[0021] Example 5: In this example, the barite concentrate contains 88.5 wt.% barium sulfate, 650 ppmw iron, and 1350 ppmw aluminum. The main impurities in the barite concentrate are silicon, aluminum, and iron in the form of aluminosilicates, quartz, and oxides. A method for deep purification of barite through medium-temperature activation and stepwise acid-base leaching, the specific steps of which are as follows: (1) The barite concentrate is crushed and ground to a particle size of less than 200 mesh to obtain barite concentrate powder; (2) Barite concentrate powder is activated and roasted at 650℃ in air atmosphere for 2.5h to thermally break the Si-O-Al bonds of aluminosilicate impurities in barite, and deagglomerate and activate the aluminosilicate lattice to obtain activated roasted sand. (3) Activated calcined sand is added to a sulfuric acid solution with a concentration of 15.0 wt%, wherein the liquid-solid ratio of the sulfuric acid solution to the activated calcined sand is 5:1 mL:g; the mixture is stirred and leached at 45°C for 2 hours; sulfuric acid is then added to adjust the sulfuric acid concentration in the system to 28.0 wt%, and the mixture is stirred and leached at 80°C for 2 hours. Solid-liquid separation is performed to obtain a graded acid leaching residue; the Fe content in the graded acid leaching residue is reduced to 46 ppmw, and the Al content is reduced to 880 ppmw. (4) The graded acid leaching residue is added to a sodium hydroxide solution with a concentration of 14.0 wt%, wherein the liquid-solid ratio of the sodium hydroxide solution to the graded acid leaching residue is 10:1 mL:g; the residue is stirred and leached at 45°C for 2 hours; sodium hydroxide is then added to adjust the sodium hydroxide concentration in the system to 25.0 wt%, and the residue is stirred and leached at 80°C for 3.5 hours. Solid-liquid separation is then performed to obtain graded alkaline leaching residue. (5) The cascade alkaline leaching residue is washed with deionized water until neutral and dried to obtain high-purity barium sulfate product; In this embodiment, the high-purity barium sulfate product contains 99.6 wt% barium sulfate, 46 ppmw iron, and 35 ppmw aluminum.

[0022] Example 6: In this example, the barite concentrate contains 90.2 wt.% barium sulfate, 520 ppmw iron, and 1480 ppmw aluminum. The main impurities in the barite concentrate are silicon, aluminum, and iron in the form of aluminosilicates, quartz, and oxides. A method for deep purification of barite through medium-temperature activation and stepwise acid-base leaching, the specific steps of which are as follows: (1) The barite concentrate is crushed and ground to a particle size of less than 200 mesh to obtain barite concentrate powder; (2) Barite concentrate powder is activated and roasted at 750℃ in air atmosphere for 1.5h to thermally break the Si-O-Al bonds of aluminosilicate impurities in barite, and deagglomerate and activate the aluminosilicate lattice to obtain activated roasted sand. (3) Activated calcined sand is added to a sulfuric acid solution with a concentration of 18.0 wt%, wherein the liquid-solid ratio of the sulfuric acid solution to the activated calcined sand is 4:1 mL:g; the mixture is stirred and leached at 55°C for 1.5 h; then sulfuric acid is added to adjust the sulfuric acid concentration in the system to 32.0 wt%, and the mixture is stirred and leached at 90°C for 1.5 h. Solid-liquid separation is performed to obtain a graded acid leaching residue; the Fe content in the graded acid leaching residue is reduced to 44 ppmw, and the Al content is reduced to 850 ppmw. (4) The graded acid leaching residue is added to a sodium hydroxide solution with a concentration of 10.0 wt%, wherein the liquid-solid ratio of the sodium hydroxide solution to the graded acid leaching residue is 6:1 mL:g; the residue is stirred and leached at 35°C for 1.5 h; sodium hydroxide is then added to adjust the sodium hydroxide concentration in the system to 22.0 wt%, and the residue is stirred and leached at 70°C for 3 h. Solid-liquid separation is then performed to obtain the graded alkaline leaching residue. (5) The cascade alkaline leaching residue is washed with deionized water until neutral and dried to obtain high-purity barium sulfate product; In this embodiment, the high-purity barium sulfate product contains 99.7 wt% barium sulfate, 44 ppmw iron, and 42 ppmw aluminum.

[0023] Example 7: In this example, the barite concentrate contains 86.5 wt.% barium sulfate, 780 ppmw iron, and 1600 ppmw aluminum. The main impurities in the barite concentrate are silicon, aluminum, and iron in the form of aluminosilicates, quartz, and oxides. A method for deep purification of barite through medium-temperature activation and stepwise acid-base leaching, the specific steps of which are as follows: (1) The barite concentrate is crushed and ground to a particle size of less than 200 mesh to obtain barite concentrate powder; (2) Barite concentrate powder is activated and roasted at 600℃ in air atmosphere for 3 hours to thermally break the Si-O-Al bonds of aluminosilicate impurities in barite, and deagglomerate and activate the aluminosilicate lattice to obtain activated roasted sand. (3) Activated calcined sand is added to a hydrochloric acid solution with a concentration of 12.0 wt%, wherein the liquid-solid ratio of the hydrochloric acid solution to the activated calcined sand is 7:1 mL:g; the mixture is stirred and leached at 35°C for 2.5 h; then hydrochloric acid is added to adjust the concentration of hydrochloric acid in the system to 24.0 wt%, and the mixture is stirred and leached at 75°C for 2.5 h. Solid-liquid separation is performed to obtain a graded acid leaching residue; the Fe content in the graded acid leaching residue is reduced to 47 ppmw, and the Al content is reduced to 900 ppmw. (4) The graded acid leaching residue is added to a sodium hydroxide solution with a concentration of 16.0 wt%, wherein the liquid-solid ratio of the sodium hydroxide solution to the graded acid leaching residue is 12:1 mL:g; the residue is stirred and leached at 50°C for 2.5 h; sodium hydroxide is then added to adjust the sodium hydroxide concentration in the system to 28.0 wt%, and the residue is stirred and leached at 85°C for 4 h. Solid-liquid separation is then performed to obtain the graded alkaline leaching residue. (5) The cascade alkaline leaching residue is washed with deionized water until neutral and dried to obtain high-purity barium sulfate product; In this embodiment, the high-purity barium sulfate product contains 99.5 wt% barium sulfate, 47 ppmw iron, and 48 ppmw aluminum.

[0024] Example 8: In this example, the barite concentrate contains 92.0 wt.% barium sulfate, 430 ppmw iron, and 1050 ppmw aluminum. The main impurities in the barite concentrate are silicon, aluminum, and iron in the form of aluminosilicates, quartz, and oxides. A method for deep purification of barite through medium-temperature activation and stepwise acid-base leaching, the specific steps of which are as follows: (1) The barite concentrate is crushed and ground to a particle size of less than 200 mesh to obtain barite concentrate powder; (2) Barite concentrate powder is activated and roasted at 580℃ in air atmosphere for 3.5h to thermally break the Si-O-Al bonds of aluminosilicate impurities in barite, and deagglomerate and activate the aluminosilicate lattice to obtain activated roasted sand. (3) Activated calcined sand is added to a sulfuric acid solution with a concentration of 13.0 wt%, wherein the liquid-solid ratio of the sulfuric acid solution to the activated calcined sand is 3.5:1 mL:g; the mixture is stirred and leached at 30°C for 2 h; then sulfuric acid is added to adjust the sulfuric acid concentration in the system to 22.0 wt%, and the mixture is stirred and leached at 70°C for 2 h. Solid-liquid separation is performed to obtain a graded acid leaching residue; the Fe content in the graded acid leaching residue is reduced to 48 ppmw, and the Al content is reduced to 910 ppmw. (4) The graded acid leaching residue is added to a sodium hydroxide solution with a concentration of 8.0 wt%, wherein the liquid-solid ratio of the sodium hydroxide solution to the graded acid leaching residue is 4:1 mL:g; the residue is stirred and leached at 30°C for 1.5 h; sodium hydroxide is then added to adjust the sodium hydroxide concentration in the system to 21.0 wt%, and the residue is stirred and leached at 65°C for 3 h. Solid-liquid separation is then performed to obtain graded alkaline leaching residue. (5) The cascade alkaline leaching residue is washed with deionized water until neutral and dried to obtain high-purity barium sulfate product; In this embodiment, the high-purity barium sulfate product contains 99.5 wt% barium sulfate, 48 ppmw iron, and 49 ppmw aluminum.

[0025] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for deep purification of barite through medium-temperature activation-step acid-base leaching, characterized in that, The specific steps are as follows: (1) The barite concentrate is crushed and ground to a particle size of less than 200 mesh to obtain barite concentrate powder; (2) Barite concentrate powder is activated and roasted at a temperature of 550~750℃ in air atmosphere for 1~4h to thermally break the Si-O-Al bonds of aluminosilicate impurities in barite, and deaggregate and activate the aluminosilicate lattice to obtain activated roasted sand. (3) The activated calcined sand is added to an acid solution with a concentration of 10.0~20.0wt%, and leached by stirring at a temperature of 25~65℃ for 1~3h; then acid is added to adjust the acid concentration in the system to 20.0~36.0wt%, and leached by stirring at a temperature of 65~95℃ for 1~3h. Solid-liquid separation is performed to obtain the graded acid leaching residue. (4) The graded acid leaching residue is added to a sodium hydroxide solution with a concentration of 7.4~20.0wt%, and leached by stirring at a temperature of 25~60℃ for 1~3h; then sodium hydroxide is added to adjust the sodium hydroxide concentration in the system to 20.0~30.0wt%, and leached by stirring at a temperature of 60~95℃ for 3~4h, and the solid and liquid are separated to obtain the graded alkaline leaching residue; (5) The cascade alkaline leaching residue is washed with deionized water until neutral and dried to obtain high-purity barium sulfate product.

2. The method for deep purification of barite by medium-temperature activation-step acid-base leaching according to claim 1, characterized in that: Step (1) The barite concentrate contains not less than 85 wt.% barium sulfate, 400-900 ppmw iron, and 1000-1700 ppmw aluminum.

3. The method for deep purification of barite by medium-temperature activation-step acid-base leaching according to claim 1, characterized in that: In step (3), the liquid-solid ratio of the acid solution to the activated calcined sand is 3~8:1 (mL:g).

4. The method for deep purification of barite by medium-temperature activation-step acid-base leaching according to claim 1, characterized in that: The acid solution is either sulfuric acid or hydrochloric acid.

5. The method for deep purification of barite by medium-temperature activation-step acid-base leaching according to claim 1, characterized in that: Step (4) The liquid-solid ratio of sodium hydroxide solution to graded acid leaching residue is 3~15:1 (mL:g).

6. The method for deep purification of barite by medium-temperature activation-step acid-base leaching according to claim 1, characterized in that: Step (5) The high-purity barium sulfate product contains ≥99.5% barium sulfate, <50ppmw iron, and <50ppmw aluminum.