Accurate sodium and calcium separation method for glauberite ore
The method of three-stage crushing and four-stage countercurrent leaching effectively separates sodium and calcium from glauberite ore, improving resource utilization and achieving zero wastewater discharge.
Patent Information
- Application Number
- CN202411306885.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-19
- Publication Date
- 2024-12-20
AI Technical Summary
Existing methods struggle to accurately separate sodium and calcium from glauberite ore, leading to a low comprehensive utilization rate of glauberite resources.
A method involving three-stage crushing and continuous four-stage countercurrent leaching process, including screening, wet ball milling, hydrocyclone classification, and multiple filter press treatments, to achieve precise separation of sodium and calcium.
Enhances sodium sulfate concentration in the leaching solution to ≥260 g/L and reduces sodium content in glauberite gypsum to ≤0.1%, facilitating high resource utilization and zero discharge of production wastewater.
Smart Images
Figure CN119160918A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of glauberite resource utilization, and in particular relates to a method for accurately separating sodium and calcium from glauberite. Background Art
[0002] Calcium glauberite ore is mainly composed of calcite, sericite, dolomite, quartz, albite, anhydrite, chlorite, biotite, potassium feldspar and plagioclase, with contents of 65.08%, 11.71%, 6.05%, 5.83%, 3.34%, 3.22%, 1.88%, 1.13%, 0.76% and 0.52% respectively. According to analysis, the water-soluble Na content in the ore is 10.51%, the purity of calcite in the ore is 63.52%, and the content of soluble components such as calcite and anhydrite is 67.10%. The content of insoluble Na2O and K2O in the ore is relatively high, which are 0.43% and 1.11% respectively. Insoluble sodium is mainly found in albite, biotite and plagioclase, insoluble potassium is mainly found in sericite, potassium feldspar and biotite, calcium is mainly found in glauberite, anhydrite and dolomite, and magnesium is mainly found in dolomite, sericite, biotite and chlorite. The glauberite particle size in the ore is coarse, and the gangue mineral particle size is fine, mostly less than 0.01mm. Calcium glauberite is distributed in a disseminated manner, and mostly has a self-shaped plate-like crystal shape.
[0003] Calcium sulfate in glauberite is a complex salt of sodium sulfate and calcium sulfate, and its molecular formula is Na2SO4·CaSO4. The complexity of its chemical composition determines that it is a sparingly soluble salt. Therefore, how to achieve accurate separation of sodium and calcium in glauberite is the key to improving the comprehensive utilization rate of glauberite resources. Summary of the invention
[0004] The purpose of the present invention is to provide a method for accurately separating sodium and calcium from glauberite, so as to solve the problem that sodium and calcium in the existing glauberite are difficult to separate, resulting in a low comprehensive utilization rate of glauberite resources.
[0005] The technical solution adopted by the present invention is as follows:
[0006] A method for accurately separating sodium and calcium from glauberite, comprising the following steps:
[0007] (1) subjecting the glauberite ore to three-stage crushing treatment, wherein the glauberite ore is first subjected to a first stage of coarse crushing treatment, and after the coarse crushing treatment, glauberite ore particles having a particle size of less than 40 mm are obtained;
[0008] (2) subjecting the glauberite particles with a particle size of less than 40 mm obtained in step (1) to a second stage of secondary crushing to obtain glauberite particles with a particle size of less than 3 mm;
[0009] (3) feeding the glauberite particles with a particle size of less than 3 mm obtained in step (2) into a wet ball mill for a third stage of crushing, and preparing glauberite slurry through the wet ball mill;
[0010] (4) feeding the glauberite slurry obtained in step (3) into a hydrocyclone for classification treatment, and during the classification treatment, feeding the glauberite particles with a particle size greater than 0.2 mm in the glauberite slurry into a wet ball mill for re-crushing to ensure that the particle size of the glauberite particles obtained after the classification treatment is less than 0.2 mm;
[0011] (5) subjecting the glauberite particles having a particle size of less than 0.2 mm in step (4) to a continuous four-stage countercurrent leaching treatment, firstly subjecting the particles to a primary leaching treatment, and then subjecting the particles to a primary filter press treatment, wherein the primary filter press treatment obtains a crude nitrate solution and a primary filter press filter cake, and the primary filter press filter cake is washed, and the washing water is fed into the wet ball mill in step (3);
[0012] (6) subjecting the washed primary filter press filter cake in step (5) to secondary leaching treatment, and then subjecting the secondary leaching treatment to secondary filter press treatment to obtain secondary leachate and secondary filter press filter cake, and passing the secondary leachate into the hydrocyclone in step (4);
[0013] (7) subjecting the secondary filter press filter cake in step (6) to a tertiary leaching treatment, and after the tertiary leaching treatment, subjecting the secondary filter press filter cake to a tertiary filter press treatment to obtain a tertiary leachate and a tertiary filter press filter cake, using the tertiary leachate to wash the primary filter press filter cake in step (5), and using the tertiary leachate to subject the primary filter press filter cake to a secondary leaching treatment in step (6);
[0014] (8) using tap water or reverse osmosis water to perform a quaternary leaching treatment on the tertiary filter press cake in step (7), performing a quaternary filter press treatment after the quaternary leaching treatment to obtain a quaternary leachate and a quaternary filter press cake, washing and squeezing the quaternary filter press cake with deionized water to obtain Glauber's salt gypsum, and using the quaternary leachate to perform a tertiary leaching treatment on the secondary filter press cake in step (7).
[0015] Furthermore, in the step (1), the glauberite ore is screened before the three-stage crushing treatment, and the glauberite ore particles with a particle size less than 40 mm obtained by screening are directly subjected to the second-stage medium crushing treatment, and the glauberite ore particles with a particle size not less than 40 mm obtained by screening are subjected to the first-stage coarse crushing treatment.
[0016] Furthermore, the sodium sulfate content in the crude nitrate water obtained in step (5) is not less than 260 g / L.
[0017] Furthermore, the sodium content of the mirabilite gypsum obtained in step (8) is not higher than 0.1%.
[0018] Furthermore, the leaching principle reaction formula of the primary leaching treatment, the secondary leaching treatment, the tertiary leaching treatment, and the quaternary leaching treatment is Na2SO4·CaSO4+xH2O=Na2SO4+CaSO4·2H2O+(x-2)H2O.
[0019] Furthermore, the leaching temperature during the primary leaching treatment, the secondary leaching treatment, the tertiary leaching treatment, and the fourth leaching treatment is 40° C., the leaching time is 30 min, and the stirring speed is 250 r / min.
[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0021] 1. In the present invention, a three-stage crushing process is firstly adopted to crush the glauberite ore into glauberite ore particles, and a continuous four-stage countercurrent leaching process is adopted for the glauberite ore particles, so that the concentration of the leaching solution is greatly improved, and the sodium sulfate concentration of the crude nitrate water is increased to the maximum extent (Na2SO4 content ≥ 260g / l), while the sodium content of the glauberite gypsum is effectively reduced (Na+ content ≤ 0.1%), and the amount of leaching agent used is minimal, and continuous and automated production is easy to realize, which effectively solves the problem that sodium and calcium in the existing glauberite ore are difficult to separate, resulting in the comprehensive utilization rate of the glauberite ore resources.
[0022] 2. In the present invention, by adopting a continuous four-stage countercurrent leaching treatment process, the leachate from the four-stage leaching treatment is effectively recycled, achieving zero discharge of production wastewater, which is more economical and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative work, among which:
[0024] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION
[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.
[0026] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0027] It should be noted that reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.
[0028] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the invented product is usually placed when in use. They are only simplified descriptions for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the descriptions, and cannot be understood as indicating or implying relative importance.
[0029] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.
[0030] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0031] A method for accurately separating sodium and calcium from glauberite, comprising the following steps:
[0032] (1) subjecting the glauberite ore to three-stage crushing treatment, wherein the glauberite ore is first subjected to a first stage of coarse crushing treatment, and after the coarse crushing treatment, glauberite ore particles having a particle size of less than 40 mm are obtained;
[0033] (2) subjecting the glauberite particles with a particle size of less than 40 mm obtained in step (1) to a second stage of secondary crushing to obtain glauberite particles with a particle size of less than 3 mm;
[0034] (3) feeding the glauberite particles with a particle size of less than 3 mm obtained in step (2) into a wet ball mill for a third stage of crushing, and preparing glauberite slurry through the wet ball mill;
[0035] (4) feeding the glauberite slurry obtained in step (3) into a hydrocyclone for classification treatment, and during the classification treatment, feeding the glauberite particles with a particle size greater than 0.2 mm in the glauberite slurry into a wet ball mill for re-crushing to ensure that the particle size of the glauberite particles obtained after the classification treatment is less than 0.2 mm;
[0036] (5) subjecting the glauberite particles having a particle size of less than 0.2 mm in step (4) to a continuous four-stage countercurrent leaching treatment, firstly subjecting the particles to a primary leaching treatment, and then subjecting the particles to a primary filter press treatment, wherein the primary filter press treatment obtains a crude nitrate solution and a primary filter press filter cake, and the primary filter press filter cake is washed, and the washing water is fed into the wet ball mill in step (3);
[0037] (6) subjecting the washed primary filter press filter cake in step (5) to secondary leaching treatment, and then subjecting the secondary leaching treatment to secondary filter press treatment to obtain secondary leachate and secondary filter press filter cake, and passing the secondary leachate into the hydrocyclone in step (4);
[0038] (7) subjecting the secondary filter press filter cake in step (6) to a tertiary leaching treatment, and after the tertiary leaching treatment, subjecting the secondary filter press filter cake to a tertiary filter press treatment to obtain a tertiary leachate and a tertiary filter press filter cake, using the tertiary leachate to wash the primary filter press filter cake in step (5), and using the tertiary leachate to subject the primary filter press filter cake to a secondary leaching treatment in step (6);
[0039] (8) using tap water or reverse osmosis water to perform a quaternary leaching treatment on the tertiary filter press cake in step (7), performing a quaternary filter press treatment after the quaternary leaching treatment to obtain a quaternary leachate and a quaternary filter press cake, washing and squeezing the quaternary filter press cake with deionized water to obtain Glauber's salt gypsum, and using the quaternary leachate to perform a tertiary leaching treatment on the secondary filter press cake in step (7).
[0040] Furthermore, in the step (1), the glauberite ore is screened before the three-stage crushing treatment, and the glauberite ore particles with a particle size less than 40 mm obtained by screening are directly subjected to the second-stage medium crushing treatment, and the glauberite ore particles with a particle size not less than 40 mm obtained by screening are subjected to the first-stage coarse crushing treatment.
[0041] Furthermore, the sodium sulfate content in the crude nitrate water obtained in step (5) is not less than 260 g / L.
[0042] Furthermore, the sodium content of the mirabilite gypsum obtained in step (8) is not higher than 0.1%.
[0043] Furthermore, the leaching principle reaction formula of the primary leaching treatment, the secondary leaching treatment, the tertiary leaching treatment, and the quaternary leaching treatment is Na2SO4·CaSO4+xH2O=Na2SO4+CaSO4·2H2O+(x-2)H2O.
[0044] Furthermore, the leaching temperature during the primary leaching treatment, the secondary leaching treatment, the tertiary leaching treatment, and the fourth leaching treatment is 40° C., the leaching time is 30 min, and the stirring speed is 250 r / min.
[0045] In the implementation process of the present invention, based on the fact that glauberite in glauberite is a complex salt of sodium sulfate and calcium sulfate, its molecular formula is Na2SO4·CaSO4, and the complexity of its chemical composition determines that it is a sparingly soluble salt, therefore, based on the following reaction: Na2SO4·CaSO4+xH2O=Na2SO4+CaSO4·2H2O+(x-2)H2O, glauberite is dissolved in water to generate dihydrated calcium sulfate precipitation and sodium sulfate aqueous solution, thereby realizing the precise separation of sodium and calcium in glauberite. Its dissolution process includes the dissolution and crystallization of sodium sulfate and calcium sulfate: one is the destruction of solute crystallization, the physical process of dissolving particles and crystal separation and diffusion into the solution, and absorbing heat; the other is the chemical process of solute molecules and water molecules combining to form hydrates and releasing heat. Therefore, the dissolution process of glauberite is a complex physical-chemical process. After calcium sulfate crystallizes, a film will be formed to cover the surface of the mineral, thereby reducing the dissolution surface area, and having a certain inhibitory effect on the dissolution of sodium sulfate. According to the dissolution characteristics of calcium glauberite in water, the single factor effects such as reaction temperature, liquid-solid ratio, feed particle size, and leaching time were studied. The test results show that the solubility of Na2SO4 reaches the maximum at 40°C, but it is not much different from the solubility at 30°C; the increase of liquid-solid ratio will increase the leaching rate, but the increase of liquid-solid ratio will increase the material flow, reduce the equipment capacity, and lead to the increase of leaching energy consumption. The test shows that the liquid-solid ratio of 1.25:1 is more appropriate; the test shows that the finer the particle size, the more conducive to leaching, and the higher the leaching rate. However, too fine ore particle size will inevitably lead to an increase in grinding costs; in order to achieve a higher leaching rate, the larger the particle size, the longer the time required, which affects production efficiency. Specifically, the glauberite ore is firstly subjected to a three-stage crushing treatment to crush the glauberite ore into glauberite ore particles, and the glauberite ore particles are subjected to a continuous four-stage countercurrent leaching treatment process to greatly improve the concentration of the leaching solution, thereby maximizing the sodium sulfate concentration of the crude nitrate water (Na2SO4 content ≥ 260g / l), while effectively reducing the sodium content of the glauberite gypsum (Na+ content ≤ 0.1%), and using the least amount of leaching agent, which is easy to realize continuous and automated production, and effectively solves the problem of the difficulty in separating sodium and calcium in the existing glauberite ore, resulting in a high comprehensive utilization rate of glauberite ore resources.
[0046] At the same time, the continuous four-stage countercurrent leaching treatment process is adopted, so that the leachate from the four-stage leaching treatment can be effectively recycled and utilized, achieving zero discharge of production wastewater, which is more economical and environmentally friendly.
[0047] Example 1
[0048] A method for accurately separating sodium and calcium from glauberite, comprising the following steps:
[0049] (1) subjecting the glauberite ore to three-stage crushing treatment, wherein the glauberite ore is first subjected to a first stage of coarse crushing treatment, and after the coarse crushing treatment, glauberite ore particles having a particle size of less than 40 mm are obtained;
[0050] (2) subjecting the glauberite particles with a particle size of less than 40 mm obtained in step (1) to a second stage of secondary crushing to obtain glauberite particles with a particle size of less than 3 mm;
[0051] (3) feeding the glauberite particles with a particle size of less than 3 mm obtained in step (2) into a wet ball mill for a third stage of crushing, and preparing glauberite slurry through the wet ball mill;
[0052] (4) feeding the glauberite slurry obtained in step (3) into a hydrocyclone for classification treatment, and during the classification treatment, feeding the glauberite particles with a particle size greater than 0.2 mm in the glauberite slurry into a wet ball mill for re-crushing to ensure that the particle size of the glauberite particles obtained after the classification treatment is less than 0.2 mm;
[0053] (5) subjecting the glauberite particles having a particle size of less than 0.2 mm in step (4) to a continuous four-stage countercurrent leaching treatment, firstly subjecting the particles to a primary leaching treatment, and then subjecting the particles to a primary filter press treatment, wherein the primary filter press treatment obtains a crude nitrate solution and a primary filter press filter cake, and the primary filter press filter cake is washed, and the washing water is fed into the wet ball mill in step (3);
[0054] (6) subjecting the washed primary filter press filter cake in step (5) to secondary leaching treatment, and then subjecting the secondary leaching treatment to secondary filter press treatment to obtain secondary leachate and secondary filter press filter cake, and passing the secondary leachate into the hydrocyclone in step (4);
[0055] (7) subjecting the secondary filter press filter cake in step (6) to a tertiary leaching treatment, and after the tertiary leaching treatment, subjecting the secondary filter press filter cake to a tertiary filter press treatment to obtain a tertiary leachate and a tertiary filter press filter cake, using the tertiary leachate to wash the primary filter press filter cake in step (5), and using the tertiary leachate to subject the primary filter press filter cake to a secondary leaching treatment in step (6);
[0056] (8) using tap water or reverse osmosis water to perform a quaternary leaching treatment on the tertiary filter press cake in step (7), performing a quaternary filter press treatment after the quaternary leaching treatment to obtain a quaternary leachate and a quaternary filter press cake, washing and squeezing the quaternary filter press cake with deionized water to obtain Glauber's salt gypsum, and using the quaternary leachate to perform a tertiary leaching treatment on the secondary filter press cake in step (7).
[0057] Example 2
[0058] On the basis of Example 1, in the step (1), the glauberite ore is screened before being subjected to the three-stage crushing treatment, and the glauberite ore particles with a particle size less than 40 mm obtained by screening are directly subjected to the second-stage medium crushing treatment, and the glauberite ore particles with a particle size not less than 40 mm obtained by screening are subjected to the first-stage coarse crushing treatment.
[0059] Example 3
[0060] Based on the above embodiment, the sodium sulfate content in the crude nitrate water prepared in step (5) is not less than 260 g / L.
[0061] Example 4
[0062] Based on the above embodiment, the sodium content of the mirabilite gypsum obtained in step (8) is not higher than 0.1%.
[0063] Example 5
[0064] Based on the above embodiments, the leaching principle reaction formula of the primary leaching treatment, the secondary leaching treatment, the tertiary leaching treatment, and the quaternary leaching treatment is Na2SO4·CaSO4+xH2O=Na2SO4+CaSO4·2H2O+(x-2)H2O.
[0065] Example 6
[0066] On the basis of the above-mentioned embodiment, the leaching temperature during the primary leaching treatment, the secondary leaching treatment, the tertiary leaching treatment and the quaternary leaching treatment is 40° C., the leaching time is 30 min, and the stirring speed is 250 r / min.
[0067] As described above, the embodiments of the present invention are described above. The preferred embodiments of the present invention are described above. If the preferred implementation methods in each preferred embodiment are not obviously self-contradictory or based on a preferred implementation method, each preferred implementation method can be arbitrarily superimposed and used in combination. The embodiments and specific parameters in the embodiments are only for the purpose of clearly describing the verification process of the invention, and are not used to limit the patent protection scope of the present invention. The patent protection scope of the present invention is still subject to its claims. Any equivalent structural changes made by using the contents of the description and drawings of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for accurately separating sodium and calcium from glauberite, characterized in that: The following steps are involved: (1) subjecting the glauberite ore to three-stage crushing treatment, wherein the glauberite ore is first subjected to a first stage of coarse crushing treatment, and after the coarse crushing treatment, glauberite ore particles having a particle size of less than 40 mm are obtained; (2) subjecting the glauberite particles with a particle size of less than 40 mm obtained in step (1) to a second stage of secondary crushing to obtain glauberite particles with a particle size of less than 3 mm; (3) feeding the glauberite particles with a particle size of less than 3 mm obtained in step (2) into a wet ball mill for a third stage of crushing, and preparing glauberite slurry through the wet ball mill; (4) feeding the glauberite slurry obtained in step (3) into a hydrocyclone for classification treatment, and during the classification treatment, feeding the glauberite particles with a particle size greater than 0.2 mm in the glauberite slurry into a wet ball mill for re-crushing to ensure that the particle size of the glauberite particles obtained after the classification treatment is less than 0.2 mm; (5) subjecting the glauberite particles having a particle size of less than 0.2 mm in step (4) to a continuous four-stage countercurrent leaching treatment, firstly subjecting the particles to a primary leaching treatment, and then subjecting the particles to a primary filter press treatment, wherein the primary filter press treatment obtains a crude nitrate solution and a primary filter press filter cake, and the primary filter press filter cake is washed, and the washing water is fed into the wet ball mill in step (3); (6) subjecting the washed primary filter press filter cake in step (5) to secondary leaching treatment, and then subjecting the secondary leaching treatment to secondary filter press treatment to obtain secondary leachate and secondary filter press filter cake, and passing the secondary leachate into the hydrocyclone in step (4); (7) subjecting the secondary filter press filter cake in step (6) to a tertiary leaching treatment, and after the tertiary leaching treatment, subjecting the secondary filter press filter cake to a tertiary filter press treatment to obtain a tertiary leachate and a tertiary filter press filter cake, using the tertiary leachate to wash the primary filter press filter cake in step (5), and using the tertiary leachate to subject the primary filter press filter cake to a secondary leaching treatment in step (6); (8) using tap water or reverse osmosis water to perform a quaternary leaching treatment on the tertiary filter press cake in step (7), performing a quaternary filter press treatment after the quaternary leaching treatment to obtain a quaternary leachate and a quaternary filter press cake, washing and squeezing the quaternary filter press cake with deionized water to obtain Glauber's salt gypsum, and using the quaternary leachate to perform a tertiary leaching treatment on the secondary filter press cake in step (7).
2. A method for accurately separating sodium and calcium from glauberite according to claim 1, characterized in that: In the step (1), the glauberite ore is screened before the three-stage crushing treatment, and the glauberite ore particles with a particle size less than 40 mm obtained by screening are directly subjected to the second stage of medium crushing treatment, and the glauberite ore particles with a particle size not less than 40 mm obtained by screening are subjected to the first stage of coarse crushing treatment.
3. A method for accurately separating sodium and calcium from glauberite according to claim 1, characterized in that: The sodium sulfate content in the crude nitrate water prepared in step (5) is not less than 260 g / L.
4. A method for accurately separating sodium and calcium from glauberite according to claim 1, characterized in that: The sodium content of the mirabilite gypsum obtained in step (8) is not higher than 0.1%.
5. A method for accurately separating sodium and calcium from glauberite according to claim 1, characterized in that: The leaching principle reaction formula of the primary leaching treatment, the secondary leaching treatment, the tertiary leaching treatment and the quaternary leaching treatment is Na2SO4·CaSO4+xH2O=Na2SO4+CaSO4·2H2O+(x-2)H2O.
6. A method for accurately separating sodium and calcium from glauberite according to claim 1, characterized in that: The leaching temperature during the primary leaching treatment, the secondary leaching treatment, the tertiary leaching treatment and the fourth leaching treatment is 40° C., the leaching time is 30 min, and the stirring speed is 250 r / min.