Method for comprehensive utilization of high-iron bauxite by separating iron and aluminum

Abstract

The application belongs to the field of bauxite dressing, and discloses a comprehensive utilization method for iron-aluminum separation of high-iron bauxite. Based on the magnetic difference between iron minerals and bauxite minerals, the high-iron bauxite is preliminarily grouped by adopting flocculation-high intensity magnetic separation process, and is divided into a magnetic mineral group and a non-magnetic mineral group. Most of the iron minerals enter the magnetic mineral group, and most of the aluminum minerals enter the non-magnetic mineral group. The non-magnetic mineral group obtains high-quality bauxite concentrate through a mature bauxite flotation process. In the magnetic material group, the aluminum minerals and the iron minerals are in complex intergrowth relationship or even exist in the form of isomorphism. Through selective mineral phase directional transformation, the aluminum minerals are transformed into soluble aluminates, and are efficiently recovered by adopting leaching process. The iron minerals are transformed into strong magnetic minerals, and iron concentrate is obtained by adopting weak magnetic separation. While greatly reducing the amount of high-temperature roasting ore, the transformation process of the iron minerals and the aluminum minerals is simultaneously adjusted, and a more ideal iron-aluminum separation effect is obtained than that of the conventional bauxite separation process.

Description

Technical Field

[0001] This invention belongs to the field of bauxite beneficiation technology, and particularly relates to a method for the comprehensive utilization of iron and aluminum separation in high-iron bauxite. Background Technology

[0002] The iron minerals in high-iron bauxite are mainly hematite, goethite, and limonite, while the aluminum minerals are mainly gibbsite, diaspore, and boehmite. Excessive iron content will cause the alumina iron content in the product to exceed the standard and affect the settling of red mud. Wei Dangsheng et al. used a strong magnetic-anion reverse flotation process to treat a high-iron bauxite, obtaining a TFe grade of 56.1% and an iron recovery rate of 51.47% in the iron concentrate. Chen Zhiyou et al. used a single strong magnetic separation process to treat a high-iron bauxite in Dengfeng, Henan, obtaining a TFe grade of 50.05% and an iron recovery rate of 54.43%. (Patent document CN 10147260) Patent A discloses a mineral processing method for high-iron bauxite using strong magnetic separation followed by anion reverse flotation. The tailings from the strong magnetic separation are concentrated and filtered to obtain bauxite concentrate I. The strong magnetic separation concentrate is then regrinded and subjected to reverse flotation froth to obtain bauxite concentrate II. The product in the flotation cell is the iron concentrate. Patent document CN100571877A also discloses a method for processing high-iron bauxite using strong magnetic separation followed by anion reverse flotation. The high-iron bauxite is first treated with strong magnetic separation, and the tailings from the strong magnetic separation are bauxite. The strong magnetic concentrate is then regrinded and subjected to anion reverse flotation to obtain the iron concentrate. Physical mineral processing methods are only suitable for processing high-iron bauxite where the iron and aluminum minerals have a simple interdistribution relationship and there is no mutual substitution between iron and aluminum elements.

[0003] Mineral phase transformation is a superior method for processing high-iron bauxite with complex iron / aluminum mineral intergrowth relationships and extremely fine iron mineral grain size. Patent documents CN 102658235 A and CN 101767057 A both propose methods for obtaining iron concentrate and bauxite concentrate using direct reduction-magnetic separation. However, direct reduction of the raw ore at a high temperature of around 1300℃ results in excessively high roasting costs, making it difficult to achieve economical utilization of high-iron bauxite. Furthermore, it fails to fully consider the difference in reasonable temperature windows for the transformation of iron and aluminum mineral phases, and while iron is transformed into metallic iron, the aluminum phase is not controlled to form water-soluble aluminum salts. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above and to provide a method for comprehensive utilization of iron and aluminum in high-iron bauxite.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] A method for the comprehensive utilization of iron and aluminum in high-speed bauxite, characterized by comprising the following steps:

[0007] (1) The high-iron bauxite ore is crushed and then subjected to a first-stage grinding-classification process to obtain a first-stage grinding product;

[0008] (2) Add dispersant and iron mineral flocculant to the first grinding product obtained in step (1) and stir to adjust the slurry so that the gangue minerals and iron minerals in the grinding product are fully dispersed, the muddy limonite and the generated fine hematite agglomerate and flocculate, and then perform strong magnetic separation to obtain magnetic and non-magnetic materials.

[0009] (3) The non-magnetic material obtained in step (2) is concentrated, and the concentrated underflow is subjected to flotation to obtain bauxite concentrate. The flotation tailings are fed into the total tailings.

[0010] (4) The magnetic material obtained in step (2) is filtered, dried and dispersed, then mixed with reducing agent and sodium salt to form briquettes, and then roasted ore is obtained through mineral phase transformation, so that the weakly magnetic hematite / limonite is transformed into a strongly magnetic mineral of metallic iron / magnetite, and the aluminum mineral is transformed into sodium aluminate soluble in water / weak alkali.

[0011] (5) The roasted ore obtained in step (4) is subjected to two-stage grinding. The product of the two-stage grinding is leached to dissolve sodium aluminate. The leaching solution is purified, impurities removed, crystallized and calcined to obtain alumina product. The leaching residue is subjected to weak magnetic separation to obtain iron concentrate and weak magnetic separation tailings.

[0012] This invention makes reasonable use of the differences in physical properties between iron and aluminum minerals in high-iron bauxite, and achieves efficient separation and recovery of iron and aluminum minerals by efficiently and precisely controlling the mineral phase transformation of iron and aluminum minerals. It also fully considers the characteristics of tailings to carry out large-scale disposal of active tailings, which can provide a new approach for the comprehensive utilization of high-iron bauxite.

[0013] In the above-mentioned method for the comprehensive utilization of iron and aluminum in high-iron bauxite, preferably, in step (1), the Fe grade in the high-iron bauxite ore is ≥14% and the Al2O3 grade is ≥45%.

[0014] Preferably, in step (1), in the high-iron bauxite ore, some aluminum and iron exist in the form of lattice substitution.

[0015] Preferably, in step (1), the first-stage grinding-classification consists of a grinding mill and a hydrocyclone; the mass fraction of -0.075mm particles in the grinding product is 80%~95%.

[0016] Preferably, in step (2), the dispersant is any one or more of NaOH, Na2CO3, sodium hexametaphosphate, and water glass, with a dosage of 100g / t to 1000g / t; the iron mineral flocculant includes any one or more of corn starch, carboxymethyl cellulose, sodium humate, ammonium humate, and tannin, with a dosage of 100g / t to 1000g / t. By adding an appropriate amount of dispersant, gangue minerals and iron minerals are fully dispersed, creating favorable conditions for the selective flocculation of iron minerals; by adding an appropriate amount of iron mineral flocculant, the muddy limonite and the fine hematite particles generated by over-grinding during the grinding process are selectively flocculated and agglomerated, and the agglomerated particle size reaches or approaches the lower limit of the particle size for high-intensity magnetic separators, thereby improving the iron recovery rate of high-intensity magnetic separation.

[0017] Preferably, in step (3), the flotation process is flotation with one rougher, two cleaners, and one scavenger or flotation with one rougher, two cleaners, and two scavengers; the flotation reagents used in the flotation process include pH adjusters, inhibitors, and collectors; the pH adjuster is any one or more of Na2CO3, NaOH, and H2SO4, with a dosage of 1000g / t to 4000g / t; the inhibitor is any one or more of starch, sodium hexametaphosphate, sodium silicate, and sodium salicylate, with a dosage of 50g / t to 1000g / t; the collector is any one or more of sodium oleate, oxidized paraffin soap, and talc oil, with a dosage of 500g / t to 2000g / t.

[0018] Preferably, in step (4), the reducing agent is any one or more of bituminous coal, anthracite, and biomass fuel, and the amount used is 10% to 30% of the mass of the mineral powder; the sodium salt is any one or more of NaOH, Na2CO3, and Na2SO4, and the amount used is 5% to 30% of the mass of the mineral powder.

[0019] Preferably, in step (4), the mineral phase transformation temperature is 900℃~1300℃, and the mineral phase transformation time is 60min~120min. During the mineral phase transformation process, the difference in the mineral phase transformation temperature window between iron minerals and aluminum minerals is fully considered. Through the synergistic effect of high temperature, reducing agent and sodium salt, the fine-grained hematite / limonite is regulated to transform into metallic iron or magnetite and the crystal lattice grows to a suitable particle size for weak magnetic separation. Aluminum minerals combine with sodium salt to form Na2O·Al2O3, which is soluble in water / weak alkali.

[0020] Preferably, in step (5), the fineness of the two-stage grinding product is: 80% of the mass of particles in the -0.075mm size range to 95% of the mass of particles in the -0.038mm size range, the leaching liquid-solid ratio is 1~4:1, the leaching temperature is room temperature to 25~260℃, the stirring intensity is 50rad / min~500rad / min, and the leaching time is 30min~90min; the weak magnetic separation includes a first weak magnetic roughing and a first weak magnetic cleaning, and the magnetic field strength of the weak magnetic roughing and the weak magnetic cleaning is 0.05T~0.35T.

[0021] Preferably, in step (5), the weak magnetic separation tailings contain 2CaO·SiO2 and / or 3CaO·SiO2, which are somewhat similar to the components of cement clinker and can be used as cement clinker additives for large-scale disposal. The weak magnetic tailings are used as cement admixtures.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) Based on the magnetic differences between iron minerals and bauxite minerals, this invention uses a flocculation-strong magnetic separation process to pre-group high-iron bauxite into magnetic mineral groups and non-magnetic mineral groups. Most of the iron minerals enter the magnetic mineral group, while most of the aluminum minerals enter the non-magnetic mineral group. The non-magnetic mineral group obtains high-quality bauxite concentrate through a mature bauxite flotation process. In the magnetic material group, the aluminum minerals and iron minerals have complex intergrowth relationships and even exist in a form of isomorphism. Through selective mineral phase directional transformation, the aluminum minerals are transformed into soluble aluminates, which can be efficiently recovered by leaching. Meanwhile, the iron minerals are transformed into strongly magnetic minerals, and iron concentrate is obtained by weak magnetic separation. While significantly reducing the amount of high-temperature roasted ore, the transformation process of iron minerals and aluminum minerals is adjusted simultaneously, resulting in a more ideal iron and aluminum separation effect than conventional bauxite beneficiation processes.

[0024] (2) In high-iron bauxite, iron and aluminum are closely associated, and fine grinding / ultrafine grinding is generally required to achieve a high degree of iron / aluminum mineral individual liberation. Limonite is prone to mud formation, and it is often lost in the strong magnetic tailings due to exceeding the lower limit of the equipment recovery particle size during strong magnetic separation. By adding appropriate amounts of dispersants and flocculants to promote selective agglomeration of iron minerals, the recovery rate of iron in strong magnetic separation can be improved, and the iron-aluminum separation effect in the strong magnetic separation process can be improved. At the same time, the residual reagents of the added iron mineral flocculants enter the bauxite flotation process, which can inhibit the floating of iron minerals and help improve the grade of bauxite flotation concentrate.

[0025] (3) In high-iron bauxite, iron and aluminum are tightly bound, and some iron and aluminum even exist in the form of lattice substitution. During the mineral phase transformation of magnetic materials, iron is replaced from the bauxite lattice by sodium salt and lattice growth occurs, which can realize the efficient recovery of iron minerals. Bauxite minerals such as gibbsite, boehmite or diaspore are transformed into soluble Na2O·Al2O3 under high temperature and sodium salt action, and then leached, purified, removed impurities, crystallized and calcined to become alumina products, thereby realizing the comprehensive recovery of aluminum minerals.

[0026] (4) The tailings of the weak magnetic separation of the present invention have undergone a high-temperature mineral phase transformation process, have high mineral activity, and contain a certain amount of 2CaO·SiO2, 3CaO·SiO2, etc., which can be used as cement clinker additives for large-scale disposal, thereby realizing the reduction of tailings in mine production. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a process flow diagram of an embodiment of the present invention. Detailed Implementation

[0029] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0030] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0031] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0032] Example 1:

[0033] The results of chemical multi-element analysis, iron phase analysis, and aluminum phase analysis of the high-iron bauxite used in this embodiment are shown in Tables 1, 2, and 3, respectively.

[0034] Table 1: Results of Multi-Element Chemical Analysis of Raw Ore

[0035]

[0036] Table 2: Phase Analysis Results of Raw Iron Ore

[0037]

[0038] Table 3: Aluminum Phase Analysis Results of Raw Ore

[0039]

[0040] Chemical analysis reveals that the main recoverable components or elements in the ore are Al₂O₃ and iron, with grades of 45.01% and 21.76%, respectively. The contents of TiO₂, Ga₂O₃, Sc₂O₃, and Nb₂O₅ are 5.02%, 0.012%, 0.008%, and 0.010%, respectively, all of which can be considered for comprehensive recovery. Iron is mainly found in hematite (limonite), with a distribution rate of 95.31%, which represents the maximum theoretical recovery rate of iron when using strong magnetic separation to separate iron minerals from the ore. Al₂O₃ mainly exists in two forms: gibbsite and diaspore, with distribution rates of 77.56% and 12.22%, respectively, totaling 89.78%. This represents the maximum theoretical recovery rate of Al₂O₃ when separating aluminum minerals from the ore.

[0041] A method for the comprehensive utilization of iron and aluminum in high-iron bauxite ore according to the present invention is shown in the process flow diagram below. Figure 1 As shown, it includes the following steps:

[0042] (1) Crushing and primary grinding: The high-iron bauxite ore is crushed into crushed samples by coarse crushing, medium crushing and fine crushing. The crushed samples enter the primary grinding-classification operation to obtain grinding products with a fineness of -0.075mm accounting for 90%.

[0043] (2) Flocculation and strong magnetic separation: The grinding product obtained in step (1) is fed into a mixing tank, and 500g / t of iron mineral flocculant is added and stirred; then a strong magnetic separation operation with a magnetic field strength of 1.20T is performed to obtain two groups of materials: magnetic material and non-magnetic material.

[0044] (3) Aluminum selection from non-magnetic materials: The non-magnetic materials obtained in step (2) are concentrated. The underflow of the concentration is processed by flotation with one roughing, two cleaning, two scavenging, and middlings returned in sequence to obtain bauxite concentrate. Na2CO3 3000g / t, (NaPO3) 660g / t, and YA-20 500g / t are added during the roughing operation. YA-20 100g / t, 100g / t, and 50g / t are added during the cleaning, scavenging, and scavenging operations, respectively. The flotation tailings are fed into the total tailings.

[0045] (4) Magnetic material phase transformation: The magnetic material obtained in step (2) is filtered, dried and dispersed, and then mixed with reducing agent and sodium salt to form briquettes. The reducing agent is anthracite, and the amount added is 30% of the mass of the mineral powder; the sodium salt is Na2CO3, and the amount added is 20% of the mass of the mineral powder. After the material is briquetted, it is roasted at 1250℃ for 120 minutes to obtain roasted ore.

[0046] (5) Comprehensive recovery of iron and aluminum from roasted ore: The roasted ore obtained in step (4) is finely ground to -0.045mm, accounting for 95%. The ground product is leached for 60 minutes under the conditions of NaOH concentration of 10%, liquid-solid ratio of 4:1, leaching temperature of 120℃ and stirring intensity of 150rad / min to obtain leachate. The leaching residue is subjected to two weak magnetic separations under the conditions of roughing magnetic field strength of 0.30T and cleaning magnetic field strength of 0.25T to obtain iron concentrate and weak magnetic separation tailings.

[0047] (6) Weak magnetic tailings disposal: used for cement admixture disposal.

[0048] This embodiment yielded an iron concentrate with a roasted ore yield of 36.05%, a TFe grade of 88.94%, and an iron recovery rate of 85.35%, and a leachate with a leaching rate of 97.25%; and a bauxite concentrate with a flotation yield of 73.01%, an Al2O3 grade of 61.24%, and an Al2O3 recovery rate of 80.36%. The combined Al2O3 recovery rate of the leachate and the bauxite concentrate was 85.10%, reaching 94.79% of the theoretical Al2O3 recovery rate.

[0049] Example 2:

[0050] The results of chemical multi-element analysis, iron phase analysis, and aluminum phase analysis of the high-iron bauxite raw material used in this embodiment are shown in Tables 4, 5, and 6, respectively.

[0051] Table 4: Results of Multi-Element Chemical Analysis of Raw Ore

[0052]

[0053] Table 5: Phase Analysis Results of Raw Iron Ore

[0054]

[0055] Table 6: Aluminum Phase Analysis Results of Raw Ore

[0056]

[0057] Chemical analysis reveals that the main recoverable components or elements in the ore are Al₂O₃ and iron, with grades of 49.44% and 14.49%, respectively. Iron is primarily found in hematite (limonite), with a distribution rate of 91.35%. Adding the iron in magnetite and carbonates, the total distribution rate is 92.78%, which represents the maximum theoretical recovery rate of iron when using strong magnetic separation to separate iron minerals from the ore. Al₂O₃ mainly exists in two forms: gibbsite and diaspore, with distribution rates of 84.69% and 4.31%, respectively, totaling 89.00%. This represents the maximum theoretical recovery rate of Al₂O₃ when separating aluminum minerals from the ore.

[0058] Using the same process as in Example 1, an iron concentrate with a roasted ore yield of 37.56%, TFe grade of 89.93%, and iron recovery rate of 88.39% was obtained, along with a leachate of 97.73%; and a bauxite concentrate with an operating yield of 68.96%, Al2O3 grade of 60.69%, and Al2O3 recovery rate of 79.38%. The combined Al2O3 recovery rate of the leachate and bauxite concentrate was 86.47%, reaching the theoretical Al2O3 recovery rate of 97.16%.

[0059] Example 3:

[0060] The raw materials used in this embodiment are the same as those used in Embodiment 2. The method for comprehensive utilization of iron and aluminum in high-iron bauxite ore according to the present invention includes the following steps:

[0061] (1) Crushing and primary grinding: The high-iron bauxite ore is crushed into crushed samples by coarse crushing, medium crushing and fine crushing. The crushed samples enter the primary grinding-classification operation to obtain grinding products with a fineness of -0.075mm accounting for 85%.

[0062] (2) Flocculation and strong magnetic separation: The grinding product obtained in step (1) is fed into a mixing tank, and 500g / t of dispersant and 700g / t of iron mineral flocculant are added and stirred; then a strong magnetic separation operation with a magnetic field strength of 1.50T is performed to obtain two groups of materials: magnetic material and non-magnetic material.

[0063] (3) Magnetic material phase transformation: The magnetic material obtained in step (2) is filtered, dried and dispersed, and then mixed with reducing agent and sodium salt to form briquettes. The reducing agent is anthracite, and the amount added is 30% of the mass of the mineral powder; the sodium salt is Na2CO3, and the amount added is 20% of the mass of the mineral powder. After the material is briquetted, it is roasted at 1250℃ for 120 minutes to obtain roasted ore.

[0064] (4) Comprehensive recovery of iron and aluminum from roasted ore: The roasted ore obtained in step (3) is finely ground to -0.045mm, accounting for 95%. The ground product is leached for 90 minutes under the conditions of NaOH concentration of 10%, liquid-solid ratio of 5:1, leaching temperature of 125℃ and stirring intensity of 150rad / min to obtain leachate. The leaching residue is subjected to two weak magnetic separations under the conditions of roughing magnetic field strength of 0.30T and cleaning magnetic field strength of 0.25T to obtain iron concentrate. The tailings of weak magnetic separation and the non-magnetic materials obtained in step (2) are combined to obtain aluminum enriched products.

[0065] This embodiment yielded an iron concentrate with a roasted ore yield of 38.57%, a TFe grade of 91.59%, and an iron recovery rate of 90.48%, as well as a leachate with a leaching rate of 98.04%. The total aluminum content in the leachate and the aluminum-enriched product was 96.08%, achieving efficient separation of iron and aluminum in high-iron bauxite.

Claims

1. A method for the comprehensive utilization of iron and aluminum in high-iron bauxite, characterized in that, Includes the following steps: (1) The high-iron bauxite ore is crushed and then subjected to a first-stage grinding-classification process to obtain a first-stage grinding product; (2) Add dispersant and iron mineral flocculant to the first grinding product obtained in step (1), stir and adjust the slurry, and then perform strong magnetic separation to obtain magnetic and non-magnetic materials; (3) The non-magnetic material obtained in step (2) is concentrated, and the concentrated underflow is subjected to flotation to obtain bauxite concentrate. The flotation tailings are fed into the total tailings. (4) The magnetic material obtained in step (2) is filtered, dried, and dispersed, then mixed with a reducing agent and sodium salt to form briquettes, and then subjected to mineral phase transformation to obtain roasted ore; the reducing agent is any one or more of bituminous coal, anthracite, and biomass fuel, and the amount used is 10% to 30% of the mineral powder mass; the sodium salt is any one or more of NaOH, Na2CO3, and Na2SO4, and the amount used is 5% to 30% of the mineral powder mass; the mineral phase transformation temperature is 900℃ to 1300℃, and the mineral phase transformation time is 60 min to 120 min; (5) The roasted ore obtained in step (4) is subjected to two-stage grinding. The product of the two-stage grinding is leached to dissolve sodium aluminate. The leaching solution is purified, impurities removed, crystallized and calcined to obtain alumina product. The leaching residue is subjected to weak magnetic separation to obtain iron concentrate and weak magnetic separation tailings. The weak magnetic separation tailings contain 2CaO·SiO2 and / or 3CaO·SiO2. The weak magnetic separation tailings are used as cement admixtures.

2. The method for comprehensive utilization of iron and aluminum separation in high-speed bauxite ore according to claim 1, characterized in that, In step (1), the Fe grade in the high-iron bauxite ore is ≥14%, and the Al2O3 grade is ≥45%.

3. The method for comprehensive utilization of iron and aluminum separation in high-speed bauxite ore according to claim 1, characterized in that, In step (1), in the high-iron bauxite ore, some aluminum and iron exist in the form of lattice substitution.

4. The method for comprehensive utilization of iron and aluminum separation in high-speed bauxite ore according to claim 1, characterized in that, In step (1), the first-stage grinding-classification consists of a grinding mill and a hydrocyclone; the mass fraction of -0.075mm particles in the grinding product is 80%~95%.

5. The method for comprehensive utilization of iron and aluminum separation in high-speed bauxite ore according to claim 1, characterized in that, In step (2), the dispersant is any one or more of NaOH, Na2CO3, sodium hexametaphosphate, and water glass, and the dosage is 100g / t to 1000g / t; the iron mineral flocculant includes any one or more of corn starch, carboxymethyl cellulose, sodium humate, ammonium humate, and tannin, and the dosage is 100g / t to 1000g / t.

6. The method for comprehensive utilization of iron and aluminum separation in high-speed bauxite ore according to claim 1, characterized in that, In step (3), the flotation process is either flotation with one rougher, two cleaners, and one scavenger or flotation with one rougher, two cleaners, and two scavengers. The flotation reagents used in the flotation process include pH adjusters, inhibitors, and collectors. The pH adjuster is any one or more of Na2CO3, NaOH, and H2SO4, with a dosage of 1000g / t to 4000g / t. The inhibitor is any one or more of starch, sodium hexametaphosphate, sodium silicate, and sodium salicylate, with a dosage of 50g / t to 1000g / t. The collector is any one or more of sodium oleate, oxidized paraffin soap, and talc oil, with a dosage of 500g / t to 2000g / t.

7. The method for comprehensive utilization of iron and aluminum separation in high-speed bauxite according to claim 1, characterized in that, In step (5), the fineness of the two-stage grinding product is as follows: 80% of the particle size is -0.075mm and 95% is -0.038mm. The leaching liquid-solid ratio is 1~4:1, the leaching temperature is 25~260℃, the stirring intensity is 50rad / min~500rad / min, and the leaching time is 30min~90min. The weak magnetic separation includes a first weak magnetic roughing and a first weak magnetic cleaning. The magnetic field strength of the weak magnetic roughing and the weak magnetic cleaning is 0.05T~0.35T.

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