Method for resource utilization of clay vanadium shale

Abstract

The application discloses a method for resource utilization of clay-containing vanadium shale, and belongs to the field of solid waste resource utilization. In view of the fact that clay-containing vanadium shale cannot be effectively utilized due to low vanadium grade and failure to meet the requirements of development and utilization, thereby causing resource waste, the vanadium grade of the clay-containing vanadium shale is improved through pre-concentration, and the process steps mainly include: (1) classification without grinding after crushing: the clay-containing vanadium shale is crushed to - (2-4 mm) without grinding, wet screening classification is carried out with 25-45 mu m as a standard, to obtain oversize and undersize, and the undersize is a pre-concentration product I; (2) three-stage open-circuit short-flow flotation after grinding of the oversize: the oversize is ground to 50-85% of -74 mu m, and then three-stage open-circuit short-flow flotation is carried out in an acid environment with pulp pH of 3-4, and a flotation concentrate is a pre-concentration product II; a new type of combined collector is independently compounded and assembled, and the mass component distribution ratio of the new type of combined collector is as follows: 50-75% of dodecyl guanidine hydrochloride, and 25-50% of isooctanol; and the mass component distribution ratio of a combined depressant is as follows: 30-50% of water glass, and 50-70% of sodium fluorosilicate.

Description

TECHNICAL FIELD

[0001] The application relates to a method for resource utilization of clay-containing vanadium shale, and belongs to the field of solid waste resource utilization. BACKGROUND

[0002] The clay-containing vanadium shale is a low-grade vanadium ore and a unique mineral resource in China, and can be used as a potential raw material for extracting vanadium. In today's vanadium market, it is generally believed that the vanadium ore with a vanadium grade (calculated in terms of V2O5, the same below) of more than 1.5% has economic extraction value, i.e. resource utilization value. However, the vanadium grade of most clay-containing vanadium shale is obviously less than 1.5%, which leads to the fact that the clay-containing vanadium shale has been discarded as solid waste for a long time and cannot be developed and utilized, resulting in serious resource waste. Therefore, it is of great significance to improve the vanadium grade of the clay-containing vanadium shale through a simple and environmentally friendly pre-concentration method before extraction of vanadium so that the clay-containing vanadium shale can meet the requirement of resource utilization.

[0003] In view of the important role of pre-concentration in the resource utilization (i.e. economic extraction of vanadium) of the clay-containing vanadium shale, researchers in the field of mineral processing have made a lot of researches and developed a plurality of process methods. However, these process methods basically remain at the laboratory stage and are difficult to popularize and apply, and have the following problems: (1) the existing pre-concentration process methods have poor applicability and are basically not suitable for low-grade clay-containing vanadium shale, and the process is relatively complex; (2) the existing pre-concentration process methods have limited enrichment degree: the improvement degree of vanadium grade is basically less than one percentage point; in individual cases, the pre-concentration degree of specific clay-containing vanadium shale in specific areas can be more than one percentage point by using a complex process method, but this is generally at the expense of the recovery rate of vanadium, which is not worth the loss; (3) the conventional and traditional flotation reagents cannot meet the requirements of pre-concentration: the flotation method is more promising, and compared with gravity separation, the pre-concentration product with a higher grade can be obtained by using the flotation method, but the existing flotation pre-concentration basically uses the reagents transplanted from the conventional and traditional flotation reagents. However, the clay-containing vanadium shale has its own unique properties and characteristics, and its mineral composition is much more complex than that of the common flotation ore, so the conventional and traditional flotation reagents cannot meet the requirements of pre-concentration of the clay-containing vanadium shale, and problems such as difficulty in flotation of vanadium-containing minerals, large consumption of reagents and poor selectivity often occur.

[0004] Therefore, in order to realize the development and utilization of the clay-containing vanadium shale as a solid waste resource, it is urgent to develop a new method for resource utilization of the clay-containing vanadium shale, i.e. a new method for pre-concentration of the clay-containing vanadium shale, so as to improve the vanadium grade of the clay-containing vanadium shale and make it meet the requirement of economic extraction of vanadium. SUMMARY

[0005] In order to realize the resource utilization of clay vanadium-containing shale, solve the problems existing in the existing pre-enrichment process, the application provides a method for resource utilization of clay vanadium-containing shale, which effectively improves the vanadium grade of clay vanadium-containing shale through pre-enrichment treatment, so that the resource utilization requirement is well met, and subsequent low-cost, low-consumption, clean and environment-friendly vanadium extraction is facilitated, and the specific method is as follows:

[0006] (1) After crushing, no grinding classification: the clay vanadium-containing shale is crushed, then water is added for slurry preparation for wet screening classification, the oversize and undersize are obtained, and the undersize is the pre-enrichment product I;

[0007] (2) The oversize is ground and subjected to three-stage open-circuit short-flow flotation: the oversize obtained in step (1) is ground to obtain a fine ore slurry, the pH value of the ore slurry is adjusted, and three-stage open-circuit short-flow flotation is carried out in an acidic environment, and the concentrate of the three-stage open-circuit short-flow flotation is combined as the pre-enrichment product II; during the flotation process, a combined collector composed of dodecyl guanidine hydrochloride and isooctanol, and a combined depressant composed of water glass and sodium fluorosilicate are used.

[0008] Preferably, the pre-enrichment product I obtained in step (1) and the pre-enrichment product II obtained in step (2) have a vanadium grade that meets or exceeds the resource utilization requirement, and can be directly used for vanadium extraction.

[0009] Preferably, the clay vanadium-containing shale in step (1) is crushed to -(2-4 mm).

[0010] Preferably, the wet screening classification in step (1) uses a 325-500 mesh screen to obtain undersize of -(25-45 μm) size fraction, and oversize of +(25-45 μm) size fraction.

[0011] Preferably, the oversize in step (2) is ground to a-74 μm content of 50-85%; the acidic environment refers to a pH value of the ore slurry of 3-4.

[0012] Preferably, the combined collector in step (2) is composed of 50-75% dodecyl guanidine hydrochloride and 25-50% isooctanol, and the total mass percentage of dodecyl guanidine hydrochloride and isooctanol is 100%.

[0013] Preferably, the combined depressant in step (2) is composed of 30-50% water glass and 50-70% sodium fluorosilicate, and the total mass percentage of water glass and sodium fluorosilicate is 100%.

[0014] Preferably, the three-stage open-circuit short-flow flotation in step (2) comprises I-stage open-circuit flotation, II-stage open-circuit flotation and III-stage open-circuit flotation; the dosage of the combined collector in the I-stage open-circuit flotation is 200-400 g / t, and the dosage of the combined depressor is 600-1000 g / t; the dosage of the combined collector in the II-stage open-circuit flotation is 100-200 g / t, and the dosage of the combined depressor is 300-500 g / t; the dosage of the combined collector in the III-stage open-circuit flotation is 50-100 g / t, and the dosage of the combined depressor is 150-250 g / t.

[0015] Preferably, the pH of the ore slurry is adjusted by dilute H2SO4 in step (2).

[0016] Preferably, the clay-containing vanadium shale has a yellow to brown appearance, is in a sheet shape, and has a clay interlayer, and the SiO2 content is not less than 75%, and the vanadium grade (calculated as V2O5) is 0.3-0.8%, belonging to low-grade clay-containing vanadium shale.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] (1) The clay-containing vanadium shale has its particularity, and the illite, vanadium mica and kaolinite are in a cryptocrystalline interbedded coexistence, and are easy to be mudified in the crushing process, and a large amount of fine particles will be produced even without grinding. The vanadium is partially distributed in the fine particle (fine particle), and generally, the finer the particle size, the higher the content (i.e. the enrichment degree) of vanadium. That is, through simple and environmentally friendly wet screening classification, the purpose of partial vanadium classification and pre-enrichment can be achieved (the undersize is the fine particle, which realizes enrichment into the subsequent vanadium extraction process; to improve the vanadium recovery rate, the oversize is the coarse particle, which is treated separately to further enrich vanadium).

[0019] At the same time, through simple and environmentally friendly wet screening classification, the fine particles in the clay-containing vanadium shale have been recovered, which can avoid the adverse effects of the easy mudification of the clay-containing vanadium shale on the subsequent flotation pre-enrichment (a large amount of fine clay particles will deteriorate the flotation process, causing the flotation process to be difficult to control), and the existing pre-enrichment process method is basically for grinding treatment of all raw ores, and the present application recovers the fine particle part (undersize) in advance through classification without grinding after crushing, and only the coarse particle (oversize) is subjected to grinding treatment, which can increase the effective treatment capacity of the mill, reduce the energy consumption of the mill and increase the processing capacity.

[0020] (2) Floatation is a kind of beneficiation process method used more for enriching vanadium-containing minerals at present. But the existing floatation pre-enrichment process generally needs to be subjected to decarburization and desliming pretreatment, generally a process of 'roasting decarburization-desliming-closed circuit floatation', which has the defects of long flow, complex process, large reagent consumption, etc. The present application adopts'screened material after grinding full open circuit short flow floatation', simple three-stage open circuit floatation can meet the requirements, not only avoids the adverse effects of middlings returning, such as deteriorating the floatation environment, reducing the concentrate quality, affecting the enrichment degree, etc., but also has the advantages of simple flow, easy operation and implementation.

[0021] In vanadium-containing shale, the useful minerals are mainly vanadium-containing aluminosilicates (represented by mica and garnet), and the gangue minerals are mainly quartz. Therefore, the floatation pre-enrichment of vanadium-containing shale is essentially the separation of aluminosilicates and quartz. As for the floatation separation of aluminosilicates and quartz, there are some studies at present, but these studies only examine the influence of main factors, and there are still a series of problems such as large reagent consumption, poor selectivity, and unsatisfactory pre-enrichment effect, etc. In the present application, the collector and depressor are independently compounded and assembled, which has the advantages of strong pertinence, high selectivity, small reagent consumption, low reagent cost, etc., can effectively realize the separation of aluminosilicates and quartz (i.e. pre-enrichment of vanadium), and simplify the floatation flow, and three-stage open circuit floatation can achieve the purpose of pre-enrichment.

[0022] (3) The floatation pre-enrichment of vanadium-containing shale is essentially the separation of aluminosilicates and quartz. Since quartz has similar physical properties, chemical composition and surface charge to silicate minerals, it is very difficult to separate the two by floatation. Most of the existing technologies are under high alkaline conditions, using alkaline earth metal ions as activators and alkyl sulfonates as collectors to preferentially collect quartz, so as to realize the separation of quartz and aluminosilicate minerals and achieve the purpose of pre-enrichment. Although the alkaline condition can avoid the environmental impact of strong acid, considering the subsequent vanadium extraction process (generally acid leaching for vanadium extraction), acid environment floatation can save the sulfuric acid consumption to the greatest extent in the subsequent acid leaching for vanadium extraction. In addition, quartz is a typical oxide mineral, and its floatation behavior has been studied a lot. The results show that under high pH value (alkaline environment), cationic collectors make quartz have good recovery rate, which obviously cannot achieve the purpose of effective separation. At the same time, the recovery rate of some silicate minerals such as kaolinite, illite and garnet increases with the decrease of pH value, and the acid environment is more conducive to the floatation of aluminosilicate minerals. Therefore, the present application carries out floatation pre-enrichment under the acid environment of pH 3-4, which is obviously more advantageous.

[0023] (4) Collector plays the most important role in realizing the pre-concentration of flotation, dodecylamine (DDA) is the most commonly used cationic collector for silicate mineral flotation, mainly relying on electrostatic attraction to adsorb on the mineral surface, making the target mineral surface hydrophobic, easy to adhere to the bubble, and enhancing the floatability, the present application selects dodecyl guanidine hydrochloride (DDGH) as the collector, because compared to —N + H3 group (in DDA + Cation), —NHC(NH)N + H3 group (in DDG + Cation) can better adsorb on silicate minerals through hydrogen bonding.

[0024] In addition, single collector often has the disadvantages of high consumption, poor selectivity and poor separation effect, while through the control of the type and complex ratio of the collector, the synergistic effect can be achieved, and better pre-concentration effect of flotation can be obtained, in the flotation of silicate minerals, alcohol can be used as an auxiliary collector, and the addition of non-ionic collector (alcohol) to the main collector can improve the selectivity of the collector, reduce the consumption of the main collector and mechanical entrainment, and improve the stability of the foam. Therefore, in the present application, the collector is self-compounded and assembled, and the mass component distribution ratio of the new combined collector DDGH-2-EH is: 50-75% dodecyl guanidine hydrochloride (DDGH), 25-50% isooctanol (2-EH).

[0025] (5) Since aluminosilicate and quartz have similar floatability, it is particularly important to inhibit the selectivity of quartz, and the commonly used inhibitors for inhibiting quartz are water glass, sodium fluosilicate and the like, but the selectivity of single inhibitor is often poor, and the consumption is very high. Therefore, in the present application, water glass and sodium fluosilicate are combined for use, and the mass component distribution ratio of the combined inhibitor is: 30-50% water glass, 50-70% sodium fluosilicate, which can play a positive synergistic effect and show a better selective inhibition effect under low consumption conditions, thereby facilitating the separation of aluminosilicate and quartz.

[0026] In summary of the above aspects, a method for resource utilization of clay-containing vanadium shale can effectively improve the vanadium grade through pre-concentration treatment, so as to meet the requirements of resource utilization, and is beneficial to subsequent low-cost, low-consumption and clean and environmental protection vanadium extraction; at the same time, the new method of the present application has the advantages of simple process, low consumption, environmental protection and easy operation. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The process flow chart of the present application. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following embodiments are merely simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be determined by the claims.

[0029] Example 1

[0030] The vanadium-bearing clayey shale used in this embodiment is yellow in appearance, flaky, with clay interlayers, SiO2 content of 80.34%, and vanadium grade of only 0.72%, making it a low-grade vanadium-bearing clayey shale.

[0031] The combined collector used in this embodiment consists of 50% dodecyl guanidine hydrochloride and 50% isooctyl alcohol; the combined inhibitor consists of 50% water glass and 50% sodium fluorosilicate.

[0032] A method for the resource utilization of vanadium-bearing clayey shale, the specific process of pre-enrichment is as follows: Figure 1 As shown, the specific steps are as follows:

[0033] (1) Non-grinding classification after crushing: Clay-containing vanadium shale is crushed to -3mm, and then water is added to adjust the slurry without grinding. Wet screening classification is carried out with 400 mesh (i.e. 38μm) as the standard to obtain the oversize and undersize. The undersize is the -38μm particle size, which is the pre-enriched product I.

[0034] (2) Oversize material after grinding and open-circuit short-process flotation: The oversize material obtained in step (1), i.e., the +38μm particle size, is ground to a -74μm content of 65%. The pulp pH is adjusted to 3 with dilute H2SO4 and then subjected to three-stage open-circuit short-process flotation. In the first stage of open-circuit flotation, the combined depressant dosage is 1000g / t and the combined collector dosage is 200g / t; in the second stage of open-circuit flotation, the combined depressant dosage is 500g / t and the combined collector dosage is 100g / t; in the third stage of open-circuit flotation, the combined depressant dosage is 250g / t and the combined collector dosage is 50g / t. The concentrates from the three-stage open-circuit flotation are combined as pre-enriched product II.

[0035] In this embodiment, the pre-enriched product has a vanadium grade of 2.31% and a recovery rate of 89.77%, which effectively achieves the pre-enrichment of vanadium and meets the requirements for the resource utilization of vanadium-bearing clay shale. Moreover, the process is simple, low-consumption, environmentally friendly, and easy to operate and implement.

[0036] Example 2

[0037] The vanadium-bearing clayey shale used in this embodiment is yellow in appearance, flaky, with clay interlayers, SiO2 content of 82.79%, and vanadium grade of only 0.68%, making it a low-grade vanadium-bearing clayey shale.

[0038] The combined collector used in the embodiment consists of 60% dodecyl guanidine hydrochloride and 40% isooctanol; the combined depressant consists of 40% water glass and 60% sodium fluosilicate.

[0039] A method for resource utilization of clay-containing vanadium shale, the specific process of the pre-concentration process is as shown in Figure 1 The specific steps are described as follows:

[0040] (1) Classification without grinding after crushing: the clay-containing vanadium shale is crushed to -3 mm, then water is added for slurry preparation, and wet screening classification is performed with 400 mesh (i.e., 38 μm) as the standard, to obtain oversize and undersize, and the undersize, i.e., -38 μm size fraction, is the pre-concentration product I.

[0041] (2) Full open-circuit short-flow flotation after grinding of the oversize: the oversize, i.e., +38 μm size fraction, obtained in step (1) is ground to -74 μm with a 75% share, and after the pH of the slurry is adjusted to 3.5 by dilute H2SO4, three-stage open-circuit short-flow flotation is performed, in the first stage, the combined depressant is used in an amount of 800 g / t, and the combined collector is used in an amount of 300 g / t; in the second stage, the combined depressant is used in an amount of 400 g / t, and the combined collector is used in an amount of 150 g / t; in the third stage, the combined depressant is used in an amount of 200 g / t, and the combined collector is used in an amount of 75 g / t; the concentrates of the three stages are combined as the pre-concentration product II.

[0042] The pre-concentration product obtained in the embodiment has a vanadium grade of 2.27% and a recovery rate of 88.45%, effectively realizing the pre-concentration of vanadium, and well meeting the requirement for resource utilization of clay-containing vanadium shale, and the process is simple, low in consumption, environmentally friendly, and easy to operate and implement.

[0043] Example 3

[0044] The clay-containing vanadium shale used in the embodiment has a yellow appearance and is in a flaky shape, the flaky interlayer is clay, the SiO2 content is 85.11%, and the vanadium grade is only 0.63%, which is a low-grade clay-containing vanadium shale.

[0045] The combined collector used in the embodiment consists of 75% dodecyl guanidine hydrochloride and 25% isooctanol; the combined depressant consists of 30% water glass and 70% sodium fluosilicate.

[0046] A method for resource utilization of clay-containing vanadium shale, the specific process of the pre-concentration process is as shown in Figure 1 The specific steps are described as follows:

[0047] (1) Broken without grinding classification: the clay vanadium-containing shale is broken to -2 mm, then without grinding, water is added to adjust the slurry to 500 mesh (i.e. 25 μm) as a standard for wet screening classification, to obtain the oversize and undersize, the undersize, i.e. -25 μm size fraction, is the pre-concentration product I.

[0048] (2) Full open-circuit short-flow flotation after grinding of the oversize: the oversize obtained in step (1), i.e. +45 μm size fraction, is ground to -74 μm with an occupancy rate of 85%, after adjusting the pH of the slurry to 4 with dilute H2SO4, three-stage open-circuit short-flow flotation is carried out, in the first stage of open-circuit flotation, the combined depressant is used in an amount of 600 g / t, and the combined collector is used in an amount of 400 g / t; in the second stage of open-circuit flotation, the combined depressant is used in an amount of 300 g / t, and the combined collector is used in an amount of 200 g / t; in the third stage of open-circuit flotation, the combined depressant is used in an amount of 150 g / t, and the combined collector is used in an amount of 100 g / t; the concentrates of the three stages of open-circuit flotation are combined as the pre-concentration product II.

[0049] The pre-concentration product obtained in this example has a vanadium grade of 2.25% and a recovery rate of 88.36%, effectively realizing the pre-concentration of vanadium, and well meeting the requirements of resource utilization of clay vanadium-containing shale, and the process is simple, low in consumption, environmentally friendly, and easy to operate and implement.

[0050] Comparative Example 1

[0051] The difference from Example 3 is that only a single dodecylamine is used as the collector, and the clay vanadium-containing shale and the combined depressant used are the same as in Example 3, and the specific process flow is the same as in Example 3, and the specific pre-concentration process flow is as shown in Figure 1 , and the specific steps are described as follows:

[0052] (1) Broken without grinding classification: the clay vanadium-containing shale is broken to -2 mm, then without grinding, water is added to adjust the slurry to 500 mesh (i.e. 25 μm) as a standard for wet screening classification, to obtain the oversize and undersize, the undersize, i.e. -25 μm size fraction, is the pre-concentration product I.

[0053] (2) Full open-circuit short-flow flotation after grinding of the oversize: the oversize obtained in step (1), i.e. +45 μm size fraction, is ground to -74 μm with an occupancy rate of 85%, after adjusting the pH of the slurry to 4 with dilute H2SO4, three-stage open-circuit short-flow flotation is carried out, in the first stage of open-circuit flotation, the combined depressant is used in an amount of 600 g / t, and the combined collector is used in an amount of 400 g / t; in the second stage of open-circuit flotation, the combined depressant is used in an amount of 300 g / t, and the combined collector is used in an amount of 200 g / t; in the third stage of open-circuit flotation, the combined depressant is used in an amount of 150 g / t, and the combined collector is used in an amount of 100 g / t; the concentrates of the three stages of open-circuit flotation are combined as the pre-concentration product II.

[0054] The vanadium grade of the pre-concentration product obtained in this embodiment is only 1.37%, and the recovery rate is only 75.42%, which is not as good as that of Example 3, because:

[0055] The collector plays the most important role in achieving flotation pre-concentration. Dodecylamine (DDA) is the most commonly used cationic collector for silicate mineral flotation, which mainly relies on electrostatic attraction to be adsorbed on the surface of the mineral, making the surface of the target mineral hydrophobic, easily adhering to the air bubbles, and enhancing the floatability. In this application, dodecyl guanidine hydrochloride (DDGH) is selected as the collector, because compared to —N + H3 group (in DDA + Cation), —NHC(NH)N + H3 group (in DDG + Cation) can be better adsorbed on silicate minerals through hydrogen bonding.

[0056] In addition, a single collector often has the disadvantages of high consumption, poor selectivity, and poor separation effect, and by controlling the type and compounding ratio of the collector, the collectors can play a synergistic role, so that a better flotation pre-concentration effect can be obtained. In silicate mineral flotation, alcohol can be used as an auxiliary collector, and the addition of non-ionic collector (alcohol) to the main collector can improve the selectivity of the collector, reduce the consumption of the main collector and mechanical entrainment, and improve the stability of the foam.

Claims

1. A method for resource utilization of clayey vanadium-containing shale, characterized in that: The specific steps are as follows: ​ (1) broken without grinding classification: the clay vanadium-containing shale is broken, then water is added for slurry preparation, and wet screening classification is carried out without grinding, to obtain oversize and undersize, and the undersize is pre-enrichment product I; (2) three-stage open-circuit short-flow flotation after grinding of oversize: the oversize obtained in step (1) is ground to obtain a fine ore slurry, the pH value of the ore slurry is adjusted, and three-stage open-circuit short-flow flotation is carried out in an acidic environment, and the concentrate of the three-stage open-circuit short-flow flotation is combined as pre-enrichment product II; a combined collector composed of dodecyl guanidine hydrochloride and isooctanol and a combined depressant composed of water glass and sodium fluorosilicate are used in the flotation process; The clay vanadium-containing shale in step (1) is broken to - (2~4mm); The wet screening classification in step (1) uses a 325~500 mesh screen to obtain undersize of - (25~45μm) size fraction and oversize of + (25~45μm) size fraction; The acidic environment in step (2) refers to the pH value of the ore slurry being 3~4; The combined collector in step (2) is composed of 50~75% dodecyl guanidine hydrochloride and 25~50% isooctanol, and the total mass percentage of dodecyl guanidine hydrochloride and isooctanol is 100%.

2. The method for resource utilization of clay vanadium shale according to claim 1, characterized in that: The pre-enrichment product I obtained in step (1) and the pre-enrichment product II obtained in step (2) can be directly used for subsequent vanadium extraction.

3. The method for utilizing clay vanadium shale resources according to claim 1, characterized in that: Step (2) grinding to 74 μm 50 to 85% 4. The method for utilizing clay vanadium shale resources according to claim 1, characterized in that: The combined depressant in step (2) is composed of 30~50% water glass and 50~70% sodium fluorosilicate, and the total mass percentage of water glass and sodium fluorosilicate is 100%.

5. The method for utilizing clay vanadium shale resources according to claim 1, characterized in that: The three-stage open-circuit short-flow flotation in step (2) includes stage I open-circuit flotation, stage II open-circuit flotation and stage III open-circuit flotation; the dosage of the combined collector in stage I open-circuit flotation is 200~400g / t, and the dosage of the combined depressant is 600~1000g / t; the dosage of the combined collector in stage II open-circuit flotation is 100~200g / t, and the dosage of the combined depressant is 300~500g / t; the dosage of the combined collector in stage III open-circuit flotation is 50~100g / t, and the dosage of the combined depressant is 150~250g / t. The three-stage open-circuit short-flow flotation in step (2) includes stage I open-circuit flotation, stage II open-circuit flotation and stage III open-circuit flotation; the dosage of the combined collector in stage I open-circuit flotation is 200~400g / t, and the dosage of the combined depressant is 600~1000g / t; the dosage of the combined collector in stage II open-circuit flotation is 100~200g / t, and the dosage of the combined depressant is 300~500g / t; the dosage of the combined collector in stage III open-circuit flotation is 50~100g / t, and the dosage of the combined depressant is 150~250g / t.

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