阅读说明：本技术 一种石棉尾矿低成本综合利用方法 (Low-cost comprehensive utilization method of asbestos tailings ) 是由 陈居玲 张付洞 夏娇彬 肖建楠 于 2020-09-21 设计创作，主要内容包括：本发明公开了一种石棉尾矿低成本综合利用方法,包括如下步骤：将石棉尾矿粉碎后送酸碱联合浸出工序,经浸出、过滤后收得酸浸出液、碱浸出液和浸出残渣；收得的酸浸出液含有硫酸镁、硫酸铁、硫酸亚铁和硫酸镍,用于分离、生产碱式碳酸镁、氧化铁颜料、磁性氧化铁和镍精矿；收得的碱浸出液主要成份为硅酸钠,即水玻璃,用于生产高分散性白炭黑；收得的浸出残渣主要成份为二氧化硅和磁铁矿。本发明综合利用过程中无废渣、废水、废气排放,实现了石棉尾矿综合利用的洁净化、无害化,不仅适用于对石棉尾矿的综合利用,而且也同样适用于其它矿物如:蛇纹石矿、红土镍矿、镁橄榄石矿、煤矸石、含钒石煤的综合利用。(The invention discloses a low-cost comprehensive utilization method of asbestos tailings, which comprises the following steps: crushing asbestos tailings, sending the crushed asbestos tailings to an acid-base combined leaching process, and leaching and filtering the crushed asbestos tailings to obtain acid leaching liquid, alkali leaching liquid and leaching residues; the obtained acid leaching solution contains magnesium sulfate, ferric sulfate, ferrous sulfate and nickel sulfate and is used for separating and producing basic magnesium carbonate, iron oxide pigment, magnetic iron oxide and nickel concentrate; the main component of the obtained alkali leaching solution is sodium silicate, namely water glass, which is used for producing the high-dispersity white carbon black; the main components of the obtained leaching residue are silicon dioxide and magnetite. The invention has no waste residue, waste water and waste gas discharge in the comprehensive utilization process, realizes the cleaning and harmless comprehensive utilization of the asbestos tailings, is not only suitable for the comprehensive utilization of the asbestos tailings, but also is also suitable for the comprehensive utilization of other minerals such as serpentine ore, laterite-nickel ore, forsterite ore, coal gangue and vanadium-containing stone coal.)

1. A low-cost comprehensive utilization method of asbestos tailings is characterized by comprising the following steps: the method comprises the following steps: crushing asbestos tailings, sending the crushed asbestos tailings to an acid-alkali combined leaching process, and leaching and filtering the crushed asbestos tailings to obtain acid leaching liquid, alkali leaching liquid and leaching residues; the obtained acid leaching solution contains magnesium sulfate, ferric sulfate, ferrous sulfate and nickel sulfate and is used for separating and producing basic magnesium carbonate, iron oxide pigment, magnetic iron oxide and nickel concentrate; the main component of the obtained alkali leaching solution is sodium silicate, namely water glass, which is used for producing the high-dispersity white carbon black; the main components of the obtained leaching residue are silicon dioxide and magnetite, and the obtained leaching residue is subjected to magnetic separation to obtain iron fine powder and then returns to the acid leaching process for cyclic decomposition, so that the comprehensive utilization of basic magnesium carbonate, iron oxide pigment or magnetic iron oxide and white carbon black mother liquor is realized, the pollution to the environment caused by the generation and discharge of wastewater is eliminated, and the systematic cyclic use of the main production raw materials of magnesium precipitator, iron neutralizer and asbestos tailing alkali leaching agent is realized; (2) the recycling method of the precipitator comprises the following steps: the method comprises the following steps: the main component of basic magnesium carbonate mother liquor produced in the production of basic magnesium carbonate is ammonium sulfate, the basic magnesium carbonate mother liquor is sent to a magnesium carbonate mother liquor comprehensive utilization process to be mixed with any one of calcium oxide, calcium hydroxide, magnesium oxide and magnesia powder for ammonolysis reaction, ammonia is volatilized while calcium sulfate dihydrate and magnesium sulfate are generated, and the volatilized ammonia is absorbed by adopting a condensation absorption or water absorption method to prepare ammonia water; step two: feeding limestone into a lime kiln for calcination to generate calcium oxide, volatilizing kiln gas, removing dust from the kiln gas, cooling and purifying to obtain carbon dioxide gas, compressing the carbon dioxide gas, feeding the compressed carbon dioxide gas into a carbonization tower, contacting the carbon dioxide gas with the ammonia water obtained in the first step in the carbonization tower, controlling process conditions to respectively prepare an ammonium carbonate solution, an ammonium bicarbonate solution and carbonized ammonia water, feeding the obtained ammonium carbonate solution, the ammonium bicarbonate solution and the carbonized ammonia water into a basic magnesium carbonate preparation process for recycling the solution as a magnesium precipitator; (3) the neutralizer adopted in the production of the iron oxide pigment and the magnetic iron oxide is ammonia water, and the recycling method of the neutralizer comprises the following steps: the main component of the iron oxide pigment and the magnetic iron oxide mother liquor produced in the production process of the iron oxide pigment and the magnetic iron oxide is ammonium sulfate, the ammonium sulfate is sent to the procedure of comprehensively utilizing the iron oxide pigment and the magnetic iron oxide mother liquor, the ammonium sulfate is mixed with any one of calcium oxide, calcium hydroxide, magnesium oxide and magnesia powder and is subjected to ammonolysis reaction, ammonia is volatilized while calcium sulfate dihydrate and magnesium sulfate are generated, the volatilized ammonia is absorbed by adopting a condensation absorption or water absorption method to prepare ammonia water, and the obtained ammonia water is returned to the production procedure of the iron oxide pigment and the magnetic iron oxide and is circularly used as a neutralizer; (4) the method for recycling the alkali leaching agent comprises the following steps: step one, producing high-dispersity white carbon black by adopting a carbon precipitation method, taking carbon dioxide as a precipitator, and packaging after precipitation, aging, separation, rinsing, drying and granulation to obtain a high-dispersity white carbon black product; and step two, the main component of the white carbon black mother liquor produced in the high-dispersity white carbon black production process is sodium carbonate, the white carbon black mother liquor is sent to the white carbon black mother liquor comprehensive utilization process to be mixed with calcium oxide or calcium hydroxide and subjected to causticization reaction, industrial light calcium carbonate and sodium hydroxide solution are obtained after separation, washing and drying, and the obtained sodium hydroxide solution is returned to the alkaline leaching process of the acid-alkali combined leaching process after concentration adjustment to be circularly used as an alkaline leaching agent.

2. The low-cost comprehensive utilization method of asbestos tailings according to claim 1, characterized in that: the magnetic separation adopts any one of a dry method and a wet method.

3. The low-cost comprehensive utilization method of asbestos tailings according to claim 1, characterized in that: the precipitant required in the preparation of the basic magnesium carbonate is any one or combination of more than two of ammonium carbonate, ammonium bicarbonate and carbonized ammonia water.

Technical Field

The invention belongs to the technical field of comprehensive utilization of tailings and hydrometallurgy, and particularly relates to a low-cost comprehensive utilization method of asbestos tailings.

Background

The asbestos tailing is a dangerous solid waste produced in the asbestos picking process, belongs to silicate minerals, mainly comprises serpentine, magnetite and the like except a small amount of asbestos, and has a main chemical composition of SiO₂MgO and a small amount of Fe₂O₃、Al₂O₃、CaO、NiO、TiO₂The advanced production process is adopted to comprehensively utilize the asbestos tailings in a recycling manner, which is necessary for social and economic sustainable development and environmental protection of mining areas, and separation and extraction of valuable elements such as silicon, magnesium, iron, nickel and aluminum in the asbestos tailings and preparation of corresponding compounds are important ways for resource utilization of the asbestos tailings, but the utilization method has the defects of large raw material consumption, high production cost and the like.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a low-cost comprehensive utilization method of asbestos tailings, which realizes the systematic internal recycling of an alkali solvent used for decomposing the asbestos tailings, a precipitator used for producing magnesium carbonate and a neutralizer used for producing iron oxide while performing acid-base combined leaching on the asbestos tailings to separate elements such as silicon, magnesium, iron, nickel and the like in the asbestos tailings and preparing white carbon black, magnesium oxide, iron oxide (pigment iron oxide or magnetic iron oxide) and nickel concentrate for high-dispersity tires, and achieves the purposes of eliminating pollution and reducing cost.

In order to achieve the design purpose, the technical scheme adopted by the invention is as follows: a low-cost comprehensive utilization method of asbestos tailings comprises the following steps:

1. crushing asbestos tailings, sending the crushed asbestos tailings to an acid-base combined leaching process, and leaching and filtering the crushed asbestos tailings to obtain acid leaching liquid, alkali leaching liquid and leaching residues; the obtained acid leaching solution contains magnesium sulfate, ferric sulfate, ferrous sulfate and nickel sulfate and is used for separating and producing basic magnesium carbonate, iron oxide pigment, magnetic iron oxide and nickel concentrate; the main component of the obtained alkali leaching solution is sodium silicate, namely water glass, which is used for producing the high-dispersity white carbon black; the main components of the obtained leaching residue are silicon dioxide and magnetite, and the obtained leaching residue is subjected to magnetic separation to obtain iron fine powder and then returns to the acid leaching process for cyclic decomposition, so that the comprehensive utilization of basic magnesium carbonate, iron oxide pigment or magnetic iron oxide and white carbon black mother liquor is realized, the pollution to the environment caused by the generation and discharge of wastewater is eliminated, and the systematic cyclic use of the main production raw materials of magnesium precipitator, iron neutralizer and asbestos tailing alkali leaching agent is realized;

2. the recycling method of the precipitator comprises the following steps: the method comprises the following steps: the main component of basic magnesium carbonate mother liquor produced in the production of basic magnesium carbonate is ammonium sulfate, the basic magnesium carbonate mother liquor is sent to a magnesium carbonate mother liquor comprehensive utilization process to be mixed with any one of calcium oxide, calcium hydroxide, magnesium oxide and magnesia powder for ammonolysis reaction, ammonia is volatilized while calcium sulfate dihydrate and magnesium sulfate are generated, and the volatilized ammonia is absorbed by adopting a condensation absorption or water absorption method to prepare ammonia water; step two: feeding limestone into a lime kiln for calcination to generate calcium oxide, volatilizing kiln gas, removing dust from the kiln gas, cooling and purifying to obtain carbon dioxide gas, compressing the carbon dioxide gas, feeding the compressed carbon dioxide gas into a carbonization tower, contacting the carbon dioxide gas with the ammonia water obtained in the first step in the carbonization tower, controlling process conditions to respectively prepare an ammonium carbonate solution, an ammonium bicarbonate solution and carbonized ammonia water, feeding the obtained ammonium carbonate solution, the ammonium bicarbonate solution and the carbonized ammonia water into a basic magnesium carbonate preparation process for recycling the solution as a magnesium precipitator;

3. the neutralizer adopted in the production of the iron oxide pigment and the magnetic iron oxide is ammonia water, and the recycling method of the neutralizer comprises the following steps: the main component of the iron oxide pigment and the magnetic iron oxide mother liquor produced in the production process of the iron oxide pigment and the magnetic iron oxide is ammonium sulfate, the ammonium sulfate is sent to the procedure of comprehensively utilizing the iron oxide pigment and the magnetic iron oxide mother liquor, the ammonium sulfate is mixed with any one of calcium oxide, calcium hydroxide, magnesium oxide and magnesia powder and is subjected to ammonolysis reaction, ammonia is volatilized while calcium sulfate dihydrate and magnesium sulfate are generated, the volatilized ammonia is absorbed by adopting a condensation absorption or water absorption method to prepare ammonia water, and the obtained ammonia water is returned to the production procedure of the iron oxide pigment and the magnetic iron oxide and is circularly used as a neutralizer;

4. the method for recycling the alkali leaching agent comprises the following steps: step one, producing high-dispersity white carbon black by adopting a carbon precipitation method, taking carbon dioxide as a precipitator, and packaging after precipitation, aging, separation, rinsing, drying and granulation to obtain a high-dispersity white carbon black product; and step two, the main component of the white carbon black mother liquor produced in the high-dispersity white carbon black production process is sodium carbonate, the white carbon black mother liquor is sent to the white carbon black mother liquor comprehensive utilization process to be mixed with calcium oxide or calcium hydroxide and subjected to causticization reaction, industrial light calcium carbonate and sodium hydroxide solution are obtained after separation, washing and drying, and the obtained sodium hydroxide solution is returned to the alkaline leaching process of the acid-alkali combined leaching process after concentration adjustment to be circularly used as an alkaline leaching agent.

The magnetic separation adopts any one of a dry method and a wet method.

The precipitant required in the preparation of the basic magnesium carbonate is any one or combination of more than two of ammonium carbonate, ammonium bicarbonate and carbonized ammonia water.

The invention has the beneficial effects that: in the whole process of the full-element comprehensive utilization of the asbestos tailings, the systematic internal recycling of an alkali impregnant for decomposing the asbestos tailings, a precipitator for producing magnesium carbonate, a neutralizing agent for producing iron oxide pigment or magnetic iron oxide and a precipitator for producing high-dispersion white carbon black is realized, the collection and transportation amount of raw materials in the production process of the asbestos tailings are greatly reduced, the production cost of the asbestos tailings is reduced, the low-cost utilization of the asbestos tailings is realized, the risk of project construction caused by the price fluctuation of the raw materials is avoided, and the difficult problems of raw material purchase and transportation of the asbestos tailings comprehensive utilization project for construction in remote areas and mining areas are solved. The invention has no waste residue, waste water and waste gas discharge in the comprehensive utilization process, realizes the cleaning and harmless comprehensive utilization of the asbestos tailings, is not only suitable for the comprehensive utilization of the asbestos tailings, but also is also suitable for the comprehensive utilization of other minerals such as serpentine ore, laterite-nickel ore, forsterite ore, coal gangue and vanadium-containing stone coal.

Detailed Description

The following detailed description of specific embodiments of the invention. A low-cost comprehensive utilization method of asbestos tailings comprises the following steps:

1. crushing asbestos tailings, sending the crushed asbestos tailings to an acid-base combined leaching process, and leaching and filtering the crushed asbestos tailings to obtain acid leaching liquid, alkali leaching liquid and leaching residues; the obtained acid leaching solution contains magnesium sulfate, ferric sulfate, ferrous sulfate and nickel sulfate and is used for separating and producing basic magnesium carbonate, iron oxide pigment, magnetic iron oxide and nickel concentrate; the main component of the obtained alkali leaching solution is sodium silicate, namely water glass, which is used for producing the high-dispersity white carbon black; the main components of the obtained leaching residue are silicon dioxide and magnetite, and the obtained leaching residue is subjected to magnetic separation to obtain iron fine powder and then returns to the acid leaching process for cyclic decomposition, so that the comprehensive utilization of basic magnesium carbonate, iron oxide pigment or magnetic iron oxide and white carbon black mother liquor is realized, the pollution to the environment caused by the generation and discharge of wastewater is eliminated, and the systematic cyclic use of the main production raw materials of magnesium precipitator, iron neutralizer and asbestos tailing alkali leaching agent is realized;

2. the recycling method of the precipitator comprises the following steps: the method comprises the following steps: the main component of basic magnesium carbonate mother liquor produced in the production of basic magnesium carbonate is ammonium sulfate, the basic magnesium carbonate mother liquor is sent to a magnesium carbonate mother liquor comprehensive utilization process to be mixed with any one of calcium oxide, calcium hydroxide, magnesium oxide and magnesia powder for ammonolysis reaction, ammonia is volatilized while calcium sulfate dihydrate and magnesium sulfate are generated, and the volatilized ammonia is absorbed by adopting a condensation absorption or water absorption method to prepare ammonia water; step two: feeding limestone into a lime kiln for calcination to generate calcium oxide, volatilizing kiln gas, removing dust from the kiln gas, cooling and purifying to obtain carbon dioxide gas, compressing the carbon dioxide gas, feeding the compressed carbon dioxide gas into a carbonization tower, contacting the carbon dioxide gas with the ammonia water obtained in the first step in the carbonization tower, controlling process conditions to respectively prepare an ammonium carbonate solution, an ammonium bicarbonate solution and carbonized ammonia water, feeding the obtained ammonium carbonate solution, the ammonium bicarbonate solution and the carbonized ammonia water into a basic magnesium carbonate preparation process for recycling the solution as a magnesium precipitator;

3. the neutralizer adopted in the production of the iron oxide pigment and the magnetic iron oxide is ammonia water, and the recycling method of the neutralizer comprises the following steps: the main component of the iron oxide pigment and the magnetic iron oxide mother liquor produced in the production process of the iron oxide pigment and the magnetic iron oxide is ammonium sulfate, the ammonium sulfate is sent to the procedure of comprehensively utilizing the iron oxide pigment and the magnetic iron oxide mother liquor, the ammonium sulfate is mixed with any one of calcium oxide, calcium hydroxide, magnesium oxide and magnesia powder and is subjected to ammonolysis reaction, ammonia is volatilized while calcium sulfate dihydrate and magnesium sulfate are generated, the volatilized ammonia is absorbed by adopting a condensation absorption or water absorption method to prepare ammonia water, and the obtained ammonia water is returned to the production procedure of the iron oxide pigment and the magnetic iron oxide and is circularly used as a neutralizer;

4. the method for recycling the alkali leaching agent comprises the following steps: step one, producing high-dispersity white carbon black by adopting a carbon precipitation method, taking carbon dioxide as a precipitator, and packaging after precipitation, aging, separation, rinsing, drying and granulation to obtain a high-dispersity white carbon black product; and step two, the main component of the white carbon black mother liquor produced in the high-dispersity white carbon black production process is sodium carbonate, the white carbon black mother liquor is sent to the white carbon black mother liquor comprehensive utilization process to be mixed with calcium oxide or calcium hydroxide and subjected to causticization reaction, industrial light calcium carbonate and sodium hydroxide solution are obtained after separation, washing and drying, and the obtained sodium hydroxide solution is returned to the alkaline leaching process of the acid-alkali combined leaching process after concentration adjustment to be circularly used as an alkaline leaching agent.

The magnetic separation adopts any one of a dry method and a wet method.

The precipitant required in the preparation of the basic magnesium carbonate is any one or combination of more than two of ammonium carbonate, ammonium bicarbonate and carbonized ammonia water.

Example 1:

(1) crushing 1000kg of asbestos tailings, sending the crushed asbestos tailings to an acid-base combined leaching process, leaching and filtering to obtain 2800kg of acid leaching solution, 2300kg of alkali leaching solution and 50kg of leaching residue, wherein the obtained acid leaching solution contains magnesium sulfate, ferric sulfate, ferrous sulfate and nickel sulfate and is used for separating and producing basic magnesium carbonate, ferric oxide pigment and nickel concentrate, the main component of the obtained alkali leaching solution is sodium silicate, namely water glass, and is used for producing high-dispersity white carbon black, and the main component of the obtained leaching residue is silicon dioxide and magnetite, 25kg of iron fine powder is separated by wet magnetic separation, and then the obtained residue is returned to the acid leaching process for cyclic decomposition;

(2) the precipitant adopted in the production of basic magnesium carbonate is 2300kg of ammonium carbonate solution, which is generated by the comprehensive utilization of basic magnesium carbonate mother liquor and is recycled;

a magnesium carbonate mother liquor comprehensive utilization process, namely mixing 4700kg of magnesium carbonate mother liquor with 700kg of calcium oxide, carrying out ammonolysis reaction, volatilizing ammonia while generating calcium sulfate dihydrate, absorbing the volatilized ammonia by adopting a condensation absorption method to prepare 1900kg of ammonia water, feeding 1400kg of limestone into a lime kiln for calcining to generate calcium oxide, volatilizing kiln gas, dedusting, cooling and purifying the kiln gas to obtain 500kg of carbon dioxide gas, compressing the carbon dioxide gas, feeding the carbon dioxide gas into a carbonization tower, contacting ammonia water in the carbonization tower, controlling process conditions to prepare 2300kg of ammonium carbonate solution, feeding the ammonium carbonate solution into a basic magnesium carbonate preparation process for recycling as a magnesium precipitator;

(3) the process adopted by the production of the iron oxide pigment is an ammonia neutralization method, 650kg of ammonia is generated by the comprehensive utilization of the iron oxide pigment mother liquor and is recycled;

in the process of comprehensively utilizing the iron oxide pigment mother liquor, 1500kg of the iron oxide pigment mother liquor and 110kg of calcium hydroxide are mixed and subjected to ammonolysis reaction, ammonia is volatilized while calcium sulfate dihydrate is generated, the volatilized ammonia is absorbed by a water absorption method to prepare 650kg of ammonia water, and the obtained ammonia water is returned to the iron oxide pigment production process to be recycled as a neutralizer;

(4) the alkali impregnant used for the alkali leaching of the asbestos tailings is 150kg of sodium hydroxide, is generated by comprehensively utilizing the high-dispersity white carbon black mother liquor and is recycled;

the production of the high-dispersity white carbon black adopts a carbon precipitation method process, carbon dioxide is used as a precipitator, and the high-dispersity white carbon black product is prepared through precipitation, aging, separation, rinsing, drying granulation and packaging, 2600kg of the high-dispersity white carbon black mother liquor is sent to a white carbon black mother liquor comprehensive utilization process, the white carbon black mother liquor is mixed with 130kg of calcium oxide and subjected to causticization reaction, 210kg of industrial light calcium carbonate and 2550kg of sodium hydroxide solution (containing 150kg of sodium hydroxide) are obtained through separation, washing and drying, and the obtained sodium hydroxide solution is returned to an alkaline leaching process of an acid-alkali combined leaching process after the concentration is adjusted and is circularly used as an alkaline leaching agent.

Example 2:

(1) 500kg of serpentine ore is crushed and then sent to the acid-alkali combined leaching process, 1000kg of acid leaching liquid, 930kg of alkali leaching liquid and 30kg of leaching residue are obtained through leaching and filtering, and the obtained acid leaching liquid contains magnesium sulfate, ferric sulfate, ferrous sulfate and nickel sulfate and is used for separating and producing basic magnesium carbonate, magnetic iron oxide and nickel concentrate. The main component of the obtained alkali leaching solution is sodium silicate, namely water glass, which is used for producing high-dispersibility white carbon black, the main components of the obtained leaching residue are silicon dioxide and magnetite, the dry process is adopted for magnetic separation to obtain 10kg of iron concentrate powder, and the residue after iron separation is returned to the acid leaching process of the acid-alkali combined leaching process for cyclic decomposition;

(2) the precipitator adopted in the production of basic magnesium carbonate is carbonized ammonia water with the dosage of 1400kg, is generated by the comprehensive utilization of basic magnesium carbonate mother liquor and is recycled;

sending 2200kg of basic magnesium carbonate mother liquor to a magnesium carbonate mother liquor comprehensive utilization process, mixing with magnesia powder and carrying out ammonolysis reaction, volatilizing ammonia while generating magnesium sulfate, absorbing the volatilized ammonia by adopting a water absorption method to prepare ammonia water, sending limestone to a lime kiln for calcining to generate calcium oxide, volatilizing kiln gas, dedusting, cooling and purifying the kiln gas to obtain carbon dioxide gas, sending the carbon dioxide gas to a carbonization tower after compression, contacting ammonia water in the carbonization tower, controlling process conditions to prepare 1400kg of carbonized ammonia water, sending the obtained carbonized ammonia water to a basic magnesium carbonate preparation process for recycling as a magnesium precipitator;

(3) the production process of the magnetic iron oxide adopts an ammonia neutralization method, and the used neutralizer ammonia is generated by comprehensively utilizing the magnetic iron oxide mother liquor and is recycled, and the using amount is 360 kg;

sending 800kg of magnetic iron oxide mother liquor to a magnetic iron oxide mother liquor comprehensive utilization process, mixing the magnetic iron oxide mother liquor with 85kg of calcium oxide, carrying out ammonolysis reaction, volatilizing ammonia while generating calcium sulfate dihydrate, absorbing the volatilized ammonia by adopting a water absorption method to prepare 360kg of ammonia water, and returning the obtained ammonia water to the magnetic iron oxide production process for recycling as a neutralizer;

(4) the alkali impregnant used for the asbestos tailing alkali leaching is sodium hydroxide, the dosage is 70kg, the alkali impregnant is generated by the comprehensive utilization of the high-dispersity white carbon black mother liquor and is recycled;

the production of the high-dispersity white carbon black adopts a carbon precipitation method process, carbon dioxide is used as a precipitator, and the high-dispersity white carbon black product is prepared by precipitation, aging, separation, rinsing, drying granulation and packaging, 1400kg of high-dispersity white carbon black mother liquor is sent to a white carbon black mother liquor comprehensive utilization process, is mixed with 100kg of calcium hydroxide and is subjected to causticization reaction, 120kg of industrial light calcium carbonate and 1350kg of sodium hydroxide solution (containing 70kg of sodium hydroxide) are obtained by separation, washing and drying, and the obtained sodium hydroxide solution is returned to an alkaline leaching process of an acid-alkali combined leaching process after the concentration is adjusted to be circularly used as an alkaline leaching agent.