A beneficiation method for efficiently recovering low-grade molybdenum bismuth sulfur polymetallic ore by flotation

Abstract

The present application belongs to the field of non-ferrous metal beneficiation, and discloses a beneficiation method for efficient recovery of low-grade molybdenum bismuth sulfur polymetallic ore flotation. First, the raw ore is ground and classified to form a slurry, and flotation reagents are added for sulfide ore full-flotation roughing, flotation cleaning, full-flotation scavenging, flotation scavenging cleaning, grinding, full-flotation cleaning reselection, and the full-flotation concentrate can obtain molybdenum concentrate, bismuth concentrate, copper concentrate and sulfur concentrate products through separation. The process can effectively reduce the grinding fineness of the first-stage grinding, preferentially recover the molybdenum bismuth sulfide minerals that have been liberated, and selectively grind the sulfide minerals that have not been fully liberated. Compared with the conventional grinding-full-flotation process, the process can save energy and reduce consumption, achieve the liberation of the molybdenum bismuth sulfide minerals with fine-grained dissemination to the greatest extent, avoid over-grinding and mudification of the liberated molybdenum bismuth sulfide minerals, improve the recovery rate, effectively reduce the flotation load of the full-flotation roughing, improve the separation efficiency of the full-flotation roughing, and comprehensively recover the copper elements in the ore.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal beneficiation technology, specifically to a beneficiation method for efficient recovery of low-grade molybdenum-bismuth-sulfur polymetallic ores via flotation. Background Technology

[0002] In this type of ore, the bismuth mineral is mainly bismuthite (Bi content is only 0.11%), the molybdenum mineral is mainly molybdenite (Mo content is as low as 0.030%), and it contains a small amount of chalcopyrite (Cu content is as low as 0.030%). Other metal sulfides are mainly pyrite and pyrrhotite. The particle size of molybdenite, bismuthite, and chalcopyrite is mainly distributed in the range of 0.005-0.15 mm, which falls into the category of fine-grained dispersibility. Molybdenite and bismuthite in the ore have good floatability, and the main challenge is efficient and low-cost monomer liberation. Pyrrhotite, on the other hand, is mainly hexagonal in crystal system, has weak magnetism, and is prone to mud formation and oxidation, making efficient flotation using conventional processes and reagent systems difficult.

[0003] Currently, the main beneficiation process for the comprehensive recovery of molybdenum, bismuth, and sulfur from this type of low-grade polymetallic ore is continuous grinding - molybdenum and bismuth can be floated - bismuth and sulfur mixed flotation process - molybdenum, bismuth, and sulfur separation and continuous grinding - molybdenum, bismuth, and sulfur full flotation - molybdenum, bismuth, and sulfur separation process. The main drawbacks of the above process are: (1) The liberation degree of the target mineral is low. When the continuous grinding reaches about 75% of -200 mesh, the liberation degrees of molybdenite, bismuthite and pyrite are only 67%, 64% and 78% respectively. If the liberation degree is further improved by fine grinding, the grinding energy consumption will be high and the target mineral will be severely muddied due to over-grinding, which will affect the comprehensive recovery technical indicators; (2) The low liberation degree of the individual minerals leads to poor flotation effect of molybdenum, bismuth and sulfur-poor intergrowth minerals in the full flotation roughing process. The recycling volume of middlings and scavenging middlings in the full flotation process is large, which seriously affects the roughing separation efficiency and ultimately results in high tailings of the target minerals and low roughing recovery rate; (3) The flotation effect of pyrite is poor and the sulfur content of the tailings is high, which seriously affects the comprehensive recovery of valuable oxide minerals in the subsequent process; (4) The copper mineral content is low and the embedded particle size is fine, so it is not economically and effectively recovered at present.

[0004] In general, existing mineral processing technologies suffer from low liberation of target minerals, leading to a large accumulation of molybdenum, bismuth, and sulfur intergrowths in the middlings and scavenging concentrates of full flotation. This results in high middlings recycling volumes, low roughing efficiency, poor recovery, and high tailings loss of target minerals. Furthermore, pyrite flotation is ineffective, with high sulfur content in the tailings, severely impacting the comprehensive recovery of valuable oxide minerals. Therefore, how to economically and efficiently improve the recovery rates of molybdenum, bismuth, and sulfur, and effectively recover chalcopyrite, has become a critical and challenging technical issue for this type of mining enterprise, requiring urgent solutions. Summary of the Invention

[0005] This invention aims to overcome the technical difficulties of low recovery rates in the beneficiation of low-grade, complex, and difficult-to-beneficiate molybdenum-bismuth-sulfur polymetallic ores using existing mineral processing technologies. It provides an energy-saving mineral processing technology for efficient and comprehensive recovery of molybdenum-bismuth-sulfur through flotation, which features low over-grinding rate of target minerals, early and green energy recovery, high mineral processing recovery rate, and comprehensive recovery of chalcopyrite.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0007] A mineral processing method for efficient recovery of low-grade molybdenum-bismuth-sulfur polymetallic ores via flotation includes the following steps:

[0008] (1) The raw ore of low-grade molybdenum-bismuth-sulfur polymetallic ore is crushed, ground and classified, and then fed into a mixing tank to prepare slurry to obtain ore feed slurry.

[0009] (2) The ore slurry obtained in step (1) is subjected to full flotation roughing of sulfide ore to obtain full flotation rough concentrate and full flotation roughing tailings;

[0010] (3) The fully floated rough concentrate obtained in step (2) is subjected to full float cleaning to obtain fully floated concentrate and fully floated middlings. The fully floated concentrate is used as feed for subsequent molybdenum-bismuth-sulfur separation operations.

[0011] (4) The full flotation roughing tailings obtained in step (2) are subjected to full flotation scavenging to obtain full flotation scavenging concentrate and flotation tailings;

[0012] (5) Mix the full flotation scavenging concentrate obtained in step (4) with the full flotation middlings obtained in step (3) and perform flotation scavenging to obtain scavenging concentrate and scavenging middlings. The scavenging middlings are returned to the full flotation roughing and re-selection in step (2).

[0013] (6) Grind the scavenged concentrate obtained in step (5) to obtain fine grinding slurry, and return the fine grinding slurry to step (3) for full flotation and re-selection;

[0014] (7) The full flotation concentrate obtained in step (3) is subjected to molybdenum-bismuth flotation desulfurization to obtain molybdenum-bismuth mixed concentrate and sulfur concentrate;

[0015] (8) The molybdenum-bismuth mixed concentrate obtained in step (7) is subjected to bismuth-copper flotation separation to obtain molybdenum concentrate and bismuth-copper mixed concentrate;

[0016] (9) Separate bismuth and copper from the bismuth-copper mixed concentrate obtained in step (8) to obtain bismuth concentrate and copper concentrate.

[0017] The mineral processing method of this invention firstly prioritizes the recovery of molybdenum, bismuth, and sulfur minerals that have been sufficiently liberated through flotation using a reasonable reagent system. Then, for target minerals that are intergrowth minerals and have entered the roughing tailings due to poor flotation adhesion, a full flotation scavenging process is performed with appropriate strong lifting. The resulting full flotation scavenging concentrate is combined with the middlings from the full flotation concentrate, which is mainly composed of intergrowth minerals and has detached from the concentrate, and then subjected to flotation scavenging. Finally, the scavenging concentrate is subjected to selective and precise grinding, allowing the selectively liberated scavenging concentrate to be returned to the full flotation concentrate for rapid and priority recovery, thereby significantly improving the full flotation concentrate recovery rate.

[0018] The mineral processing method of this invention prioritizes the recovery of molybdenum-bismuth sulfide minerals that have already been liberated. For molybdenum, bismuth, and sulfur minerals with poor liberation in the middlings and scavenging concentrates of full flotation, a concentrated flotation scavenging process is adopted, followed by selective grinding with an abrasive mill or vertical mill and then returning to the full flotation process for priority recovery. This process can not only significantly reduce the circulating load of middlings and reduce over-grinding and mudding of target minerals, thereby improving flotation separation efficiency and recovery rate, but also appropriately coarsen the grinding fineness before full flotation. Compared with grinding to the effective liberation of useful minerals in a single process, this method can significantly reduce grinding costs.

[0019] The mineral processing method of this invention takes advantage of the fact that the chalcopyrite in the ore is small in quantity and is mostly enriched in bismuth concentrate to form a bismuth-copper mixed concentrate. It makes full use of the characteristic of adding a modifier to increase the difference in floatability between bismuth ore and chalcopyrite, and finally achieves effective recovery of chalcopyrite, obtaining a copper concentrate grade of 15% to 20% and a copper recovery rate of >40%.

[0020] In summary, this invention targets low-grade, complex, and difficult-to-process molybdenum-bismuth-sulfur polymetallic ores. It fully utilizes the differences in the degree of liberation and floatability of the target minerals, prioritizing the recovery of well-liberated sulfide minerals. Intergrowth sulfide ores undergo appropriate enhanced flotation enrichment before selective grinding and preferential separation for recovery. This process features low grinding over-grinding of the target minerals, early and efficient recovery, energy efficiency, and high beneficiation recovery rates. The recovery rates of molybdenum, bismuth, and sulfur can be increased by 9–12 percentage points, 8–10 percentage points, and 12–15 percentage points, respectively, compared to conventional beneficiation processes.

[0021] In the above-mentioned beneficiation method, preferably, in step (1), the raw ore of the low-grade molybdenum-bismuth-sulfur polymetallic ore includes bismuthite, molybdenite, pyrite, pyrrhotite and chalcopyrite; the raw ore contains 0.05%-0.5% Bi, 0.02%-0.5% Mo, 0.5%-8% S and 0.01%-0.05% Cu.

[0022] More preferably, the molybdenite, bismuthite and chalcopyrite in the raw ore of the low-grade molybdenum-bismuth-sulfur polymetallic ore have an intercalation particle size distribution of 0.005 to 0.15 mm.

[0023] Preferably, in step (1), the fineness of the slurry after grinding and classifying the raw ore is 50% to 80% -0.075 mm.

[0024] Preferably, in step (1), the mass concentration of the slurry after conditioning is 30% to 65%.

[0025] Preferably, in steps (2), (3), (4), and (5), the modifiers used in the full flotation roughing, full flotation cleaning, full flotation scavenging, and flotation scavenging of the sulfide ore are selected from any one or a combination of sodium carbonate, water glass, sodium humate, copper sulfate, lead nitrate, and sodium hexametaphosphate, and the collectors used are selected from one or a combination of non-polar oils, xanthates, sulfur-nitrogen compounds, thioamine esters, and thiols.

[0026] More preferably, the collector is selected from one or a combination of several of butyl xanthate, ethyl xanthate, pentyl xanthate, ethyl thiocyanate, dodecanethiol, MBT, Z200, kerosene, emulsified kerosene, and diesel oil.

[0027] More preferably, in step (2), the amount of modifier used in the full flotation roughing of the sulfide ore is 50g / t-5000g / t, and the amount of collector used is 10g / t-1000g / t; in steps (3), (4), and (5), the amount of modifier used in the full flotation cleaning, full flotation scavenging, and scavenging cleaning is 0g / t-1000g / t, and the amount of collector used is 0g / t-300g / t.

[0028] Preferably, in step (6), the grinding fineness is ≥90% of the -200 mesh particle size, or the degree of liberation of molybdenum, bismuth, and sulfur minerals in the overflow slurry is ≥70%, and the grinding equipment is an abrasive mill or a vertical mill. The middlings of the full flotation concentrate are mainly sulfide minerals existing in the form of intergrowths, and the middlings regrinding equipment is an abrasive mill or a stirred mill.

[0029] Preferably, in step (7), the modifier used in the molybdenum-bismuth flotation desulfurization is selected from one or a combination of activated carbon, lime, mercapto compounds, sodium cyanurate, acetone cyanohydrin, water glass, and sodium hexametaphosphate, and the collector used is selected from any one or a combination of non-polar oil, xanthates, sulfur-nitrogen compounds, and thiols.

[0030] Preferably, in step (8), the flotation process for separating bismuth-inhibiting copper and molybdenum consists of one roughing, five cleaning, and three scavenging processes. The modifier used is selected from one or a combination of sodium sulfide, water glass, sodium hexametaphosphate, mercapto compounds, sodium sulfite, and sodium humate. The collector used is selected from any one or a combination of nonpolar oils, xanthates, sulfur-nitrogen compounds, and thiols.

[0031] Preferably, in step (9), the modifier used for bismuth-copper separation is selected from any one or a combination of several of water glass, copper sulfate, sodium hexametaphosphate, sodium sulfite, and sodium sulfide, and the collector used is selected from any one or a combination of several of xanthates, sulfur nitrogen compounds, thioamine esters, and thiols.

[0032] Compared with the prior art, the advantages of the present invention are as follows:

[0033] 1) This invention follows the principle of "early recovery if possible" and makes full use of the differences in the degree of liberation and floatability of different sulfide minerals. It prioritizes the recovery of sulfide minerals that are fully liberated. After appropriate enhanced enrichment by flotation of intergrowth sulfide minerals, a selective grinding-preferential separation and recovery process is adopted. This can effectively avoid over-grinding and mudding of liberated molybdenum-bismuth sulfide minerals in subsequent regrinding operations, and can also perform selective and precise grinding and liberation of intergrowth sulfide minerals, which has the advantages of energy saving and consumption reduction.

[0034] 2) This invention addresses the complex intermingling relationships and uneven particle size among minerals in low-grade, complex, and difficult-to-process molybdenum-bismuth-sulfur polymetallic ores. It employs a selective and precise regrinding-return-to-selection-recovery process for intergrowth sulfide minerals. This process achieves selective liberation of a large number of poorly liberated intergrowth minerals in the middlings of the full flotation concentrate and the scavenging concentrate. This not only significantly improves the liberation degree of the target minerals but also effectively prevents over-grinding, thereby significantly improving the quality and recovery rate of the full flotation concentrate.

[0035] 3) This invention innovatively changes the conventional method of returning middlings (middlings from full flotation and scavenging concentrate) generated during flotation to full flotation roughing operations in a centralized flotation re-enrichment-selective precision grinding-return to full flotation for priority separation and recovery. On the one hand, it significantly improves the liberation degree of the target minerals and avoids the impact and fluctuation of concentrate indicators caused by a large number of intergrowths in the middlings. On the other hand, it implements priority separation and recovery of sulfide minerals that have been liberated after regrinding, which greatly improves the separation efficiency of flotation operations.

[0036] 4) The mineral processing method of this invention can be used to comprehensively recover molybdenum, bismuth and sulfur minerals from low-grade, complex and difficult-to-process polymetallic ores. Compared with conventional mineral processing methods, the recovery rate of Mo is increased by 9 to 12 percentage points, the recovery rate of Bi is increased by 8 to 10 percentage points, and the recovery rate of S is increased by 12 to 15 percentage points.

[0037] 5) The mineral processing method of this invention takes advantage of the characteristic that most of the chalcopyrite in the ore is enriched in the bismuth concentrate to form a bismuth-copper mixed concentrate. It makes full use of the characteristic of adding modifiers to increase the difference in floatability between bismuth ore and chalcopyrite, and finally realizes that chalcopyrite can be effectively recovered from non-recoverable to effective, and obtains a copper concentrate grade of 15% to 20% and a copper recovery rate of >40%. Attached Figure Description

[0038] 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.

[0039] Figure 1 The above are flow charts of the high-efficiency recovery flotation process for low-grade molybdenum-bismuth-sulfur polymetallic ore in a certain concentrator plant, as shown in Embodiments 1-2 of the present invention.

[0040] Figure 2 The following is a flow chart of the mineral processing technology for Comparative Examples 1-2. Detailed Implementation

[0041] 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.

[0042] 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.

[0043] 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.

[0044] Example 1:

[0045] A mineral processing method for efficient recovery of low-grade molybdenum-bismuth-sulfur polymetallic ores by flotation according to the present invention is as follows:

[0046] The low-grade, complex, and difficult-to-process molybdenum-bismuth-sulfur polymetallic ore processed in this embodiment contains a wide variety of minerals. Molybdenum is mainly present in the form of molybdenite, with a distribution rate of 92%. Bismuth is mainly present in the form of bismuthite, with a distribution rate of 90%, bismuth occurring as bismuth sulfide accounting for 9%, and native bismuth accounting for 1%. Copper is mainly present in the form of chalcopyrite. Sulfur is mainly present in the forms of pyrite and pyrrhotite, with a distribution rate as high as 95%, and sulfur accounts for 5% of sulfates. The most abundant non-metallic minerals are garnet and fluorite, followed by quartz, sericite, calcite, plagioclase, and potassium feldspar, with small amounts of pyroxene, diopside, biotite, actinolite, topaz, and chlorite. The pyrite in the ore has a slightly coarser grain size, mainly distributed between 0.2 mm and 0.6 mm, belonging to the medium-fine grain dissemination category; the molybdenite and bismuth minerals have relatively finer grain sizes, mainly distributed between 0.005 mm and 0.10 mm, belonging to the micro-fine grain dissemination category. The ore contains 0.059% Mo, 0.11% Bi, 0.03% Cu, and 1.00% S.

[0047] Adopting such Figure 1 The efficient flotation and beneficiation method for molybdenum-bismuth-sulfur polymetallic ores shown herein comprises the following specific steps:

[0048] (1) The grinding product with a molybdenum content of 0.059%, a bismuth content of 0.11%, and a sulfur content of 1.00% (70% of which have a fineness of -0.075mm) is slurried in a mixing tank to obtain a feed slurry with a slurry concentration of about 50%.

[0049] (2) Add 600g / t of sodium carbonate, 750g / t of water glass, 90g / t of collector ester 105, and 30g / t of frother BK205 to the ore slurry in step (1) for flotation (i.e., full flotation roughing of sulfide ore) to obtain full flotation rough concentrate of molybdenum bismuth sulfide and full flotation roughing tailings.

[0050] (3) The fully floated rough concentrate from step (2) is subjected to a first-stage fine cleaning (i.e., full float fine cleaning), with a water glass dosage of 150g / , to obtain the fully floated concentrate and the fully floated fine middlings;

[0051] (4) The tailings from the full flotation roughing process in step (2) are subjected to a first enhanced scavenging process (i.e., full flotation scavenging), with collectors ester 105 and BK205 at 30 g / t and 10 g / t respectively, to obtain full flotation scavenging concentrate and final tailings (i.e. flotation tailings).

[0052] (5) After fully mixing the middlings of the full flotation concentrate in step (3) with the full flotation scavenging concentrate in step (4), perform a blank concentrate (i.e. flotation scavenging concentrate) to obtain scavenging concentrate and scavenging middlings. The scavenging middlings are returned to the full flotation roughing operation.

[0053] (6) The scavenged concentrate obtained in step (5) is ground for one stage using an abrasive mill to obtain grinding overflow slurry. The grinding overflow slurry is returned to the full flotation cleaning operation for separation. The fineness of the overflow slurry is -200 mesh, accounting for 95%.

[0054] (7) The full flotation concentrate obtained in step (3) is subjected to molybdenum-bismuth flotation desulfurization. The flotation process consists of one roughing, three cleaning, and three scavenging. The collector kerosene is 20 g / t, and the modifiers lime, acetone cyanohydrin, activated carbon, and water glass are 20 kg / t, 1000 g / t, 1500 g / t, and 2000 g / t, respectively.

[0055] (8) The molybdenum-bismuth mixed concentrate obtained in step (7) is subjected to bismuth-copper flotation separation. The flotation process consists of one roughing, five cleaning, and three scavenging processes. The collector kerosene is 50 g / t, and the modifiers Na2S and water glass are 5000 g / t and 1000 g / t, respectively.

[0056] (9) The bismuth-copper mixed concentrate obtained in step (8) is subjected to bismuth-copper flotation separation. The flotation process consists of one roughing, two cleaning and one scavenging. The collector butyl xanthate is 100 g / t, and the modifiers copper sulfate and ethyl thiocyanate are 100 g / t and 1000 g / t, respectively, to obtain bismuth concentrate and copper concentrate.

[0057] This method yielded a full flotation concentrate with a yield of 2.56%, a Mo grade of 2.10% and a Mo recovery of 91.12%, a Bi grade of 3.83% and a Bi recovery of 89.13%, and a S grade of 36.36% and a S recovery of 93.08%. After separation and beneficiation, the molybdenum-bismuth-sulfur full flotation concentrate yielded a molybdenum concentrate with a Mo grade of 50.35% and a Mo recovery of 85.65%, a bismuth concentrate with a Bi grade of 34.32% and a Bi recovery of 80.22%, and a copper concentrate with a Cu grade of 18% and a Cu recovery of 40%.

[0058] Example 2:

[0059] A mineral processing method for efficient recovery of low-grade molybdenum-bismuth-sulfur polymetallic ores by flotation according to the present invention is as follows:

[0060] The low-grade, complex, and difficult-to-process molybdenum-bismuth-sulfur polymetallic ore processed in this implementation has an extremely complex chemical composition. The recoverable components for beneficiation are molybdenum, bismuth, copper, and sulfur, with contents of 0.065%, 0.12%, 0.04%, and 1.10%, respectively. Molybdenum and bismuth minerals in the ore mainly exist in the form of molybdenite and bismuthite, while copper minerals mainly exist in the form of chalcopyrite. Other metallic sulfides are predominantly pyrite and pyrrhotite. Gangue minerals mainly consist of garnet, quartz, potassium feldspar, plagioclase, sericite, biotite, and calcite. The sulfide particle size in the ore is mainly distributed between 0.10 mm and 0.40 mm; the molybdenite and bismuth minerals have relatively finer particle sizes, mainly distributed between 0.005 mm and 0.10 mm, falling into the category of fine-grained dissemination.

[0061] Adopting such Figure 1 The efficient flotation and beneficiation method for molybdenum-bismuth-sulfur polymetallic ores shown herein comprises the following specific steps:

[0062] (1) The grinding product with a molybdenum content of 0.065%, bismuth content of 0.12%, copper content of 0.04%, and sulfur content of 1.10% (70% of which have a fineness of -0.075mm) is slurried in a mixing tank to obtain a feed slurry with a slurry concentration of about 50%.

[0063] (2) Add 600g / t of sodium carbonate, 750g / t of water glass, 100g / t of collector ethyl thiocyanate, and 30g / t of frother BK-205 to the ore slurry in step (1) and carry out flotation (i.e., full flotation roughing of sulfide ore) to obtain full flotation rough concentrate and full flotation roughing tailings.

[0064] (3) The fully floated rough concentrate from step (2) is subjected to a first-stage fine cleaning (i.e., full float fine cleaning), with a water glass dosage of 200g / , to obtain the fully floated concentrate and the fully floated fine middlings;

[0065] (4) The tailings from the full flotation roughing process in step (1) are subjected to a first enhanced scavenging process (i.e., full flotation scavenging), with collectors ethyl thiocyanate and BK-205 at 30 g / t and 10 g / t respectively, to obtain full flotation scavenging concentrate and final tailings (i.e. flotation tailings).

[0066] (5) After fully mixing the middlings from the full flotation concentrate in step (3) with the full flotation scavenging concentrate in step (4), perform a blank concentrate (i.e., full flotation scavenging concentrate) to obtain full flotation scavenging concentrate and scavenging tailings. The scavenging tailings are returned to the full flotation roughing operation.

[0067] (6) The scavenged concentrate obtained in step (5) is ground for one stage using an abrasive mill to obtain grinding overflow slurry. The grinding overflow slurry is returned to the full flotation cleaning operation for further selection. The fineness of the overflow slurry is -200 mesh, accounting for 95%.

[0068] (7) The full flotation concentrate obtained in step (3) is subjected to molybdenum-bismuth flotation desulfurization. The flotation process consists of one roughing, three cleaning, and three scavenging. The collector kerosene is 30 g / t, and the modifiers lime, acetone cyanohydrin, activated carbon, and water glass are 25 kg / t, 1200 g / t, 1000 g / t, and 1500 g / t, respectively.

[0069] (8) The molybdenum-bismuth mixed concentrate obtained in step (7) is subjected to molybdenum-bismuth separation. The flotation process consists of one roughing, five cleaning, and three scavenging processes. The collector kerosene is 60 g / t, and the modifiers Na2S and water glass are 3000 g / t and 800 g / t, respectively.

[0070] (9) The bismuth-copper mixed concentrate obtained in step (8) is subjected to bismuth-copper flotation separation. The flotation process consists of one roughing, two cleaning and one scavenging. The collector butyl xanthate is 120 g / t, and the modifiers copper sulfate and ethyl thiocyanate are 120 g / t and 1500 g / t, respectively, to obtain bismuth concentrate and copper concentrate.

[0071] This method yielded a full flotation concentrate with a yield of 2.88%, a Mo grade of 2.05% and a Mo recovery of 90.83%, a Bi grade of 3.71% and a Bi recovery of 89.04%, and a S grade of 35.48% and a S recovery of 92.89%. After separation and beneficiation, the molybdenum-bismuth-sulfur full flotation concentrate yielded a molybdenum concentrate with a Mo grade of 49.50% and a Mo recovery of 85.07%, a bismuth concentrate with a Bi grade of 33.80% and a Bi recovery of 80.00%, and a copper concentrate with a Cu grade of 20% and a Cu recovery of 38%.

[0072] Comparative Example 1:

[0073] use Figure 1 The conventional full flotation process shown is used to process low-grade molybdenum-bismuth-sulfur polymetallic ore. The raw ore is the same as in Example 1. The main difference from Example 1 is that the grinding particle size of the raw ore in step (1) is finer, with the fineness of -0.075mm increasing by 10 percentage points. In step (5), the middlings and scavenging concentrate of the full flotation concentrate are not enriched by scavenging and selective grinding. The middlings and scavenging concentrate are returned to the roughing operation. The specific steps are as follows:

[0074] (1) The grinding product with a molybdenum content of 0.059%, a bismuth content of 0.11%, and a sulfur content of 1.00% (80% of which have a fineness of -0.075mm) is slurried in a mixing tank to obtain a feed slurry with a slurry concentration of about 50%.

[0075] (2) Add 600g / t of sodium carbonate, 750g / t of water glass, 120g / t of collector ester 105 and 30g / t of frother BK205 to the ore slurry in step (1) for flotation (i.e., full flotation roughing of sulfide ore) to obtain molybdenum bismuth sulfide full flotation rough concentrate and roughing tailings.

[0076] (3) The fully floated rough concentrate from step (2) is subjected to a first-stage fine cleaning (i.e., full float fine cleaning), with a water glass dosage of 150g / , to obtain the fully floated concentrate and the finely cleaned middlings;

[0077] (4) The roughing tailings in step (1) are subjected to a full flotation scavenging process, with collectors ester 105 and BK205 at 30 g / t and 10 g / t respectively, to obtain full flotation scavenging concentrate and final tailings (i.e. flotation tailings).

[0078] (5) Return the middlings from step (3) and the full flotation scavenging concentrate from step (4) to the full flotation roughing operation;

[0079] (6) The molybdenum-bismuth-sulfur full flotation concentrate from step (3) was used as the feed for molybdenum-bismuth-sulfur separation. The yield of the full flotation concentrate was 3.34%, with a Mo grade of 1.50% and a Mo recovery rate of 84.92%, a Bi grade of 2.70% and a Bi recovery rate of 81.98%, and a S grade of 27.42% and a S recovery rate of 83.26%. After separation and beneficiation, the molybdenum-bismuth-sulfur full flotation concentrate yielded a molybdenum concentrate with a Mo grade of 40.05% and a Mo recovery rate of 76.43%, and a bismuth concentrate with a Bi grade of 29.60% and a Bi recovery rate of 70.78%. Copper was not recovered.

[0080] Comparative Example 2:

[0081] use Figure 2 The conventional process flow shown is used to process low-grade molybdenum-bismuth-sulfur polymetallic ore. The raw ore is the same as in Example 2. The main difference from Example 2 is that in step (1), the grinding particle size of the raw ore is finer, with the fineness of -0.075mm increasing by 10 percentage points. In step (5), the middlings and scavenging concentrate of the full flotation concentrate are not enriched by scavenging and selective grinding, and the middlings and scavenging concentrate are returned to the roughing operation. The specific steps are as follows:

[0082] (1) The grinding product with a molybdenum content of 0.065%, a bismuth content of 0.12%, and a sulfur content of 1.10% (80% of which have a fineness of -0.075mm) is slurried in a mixing tank to obtain a slurry concentration of about 50%.

[0083] (2) Add 600g / t of sodium carbonate, 750g / t of water glass, 120g / t of collector ethyl thiocyanate, and 30g / t of frother BK205 to the ore slurry in step (1) for flotation (i.e., full flotation roughing of sulfide ore) to obtain molybdenum bismuth sulfide full flotation rough concentrate and roughing tailings.

[0084] (3) The fully floated rough concentrate from step (2) is subjected to a first-stage fine cleaning (i.e., full float fine cleaning), with a water glass dosage of 200g / , to obtain the fully floated concentrate and the finely cleaned middlings;

[0085] (4) The roughing tailings in step (1) are subjected to a full flotation scavenging process with collectors ethyl thiocyanate and BK205 at 30 g / t and 10 g / t respectively, to obtain full flotation scavenging concentrate and final tailings (i.e. flotation tailings).

[0086] (5) Return the middlings from step (3) and the full flotation scavenging concentrate from step (4) to the full flotation roughing operation;

[0087] (6) The molybdenum-bismuth-sulfur full flotation concentrate from step (3) was used as the feed for molybdenum-bismuth-sulfur separation. The yield of the full flotation concentrate was 3.77%, with a Mo grade of 1.45% and a Mo recovery rate of 84.10%, a Bi grade of 2.60% and a Bi recovery rate of 81.68%, and a S grade of 24.22% and a S recovery rate of 83.01%. After separation and beneficiation, the molybdenum-bismuth-sulfur full flotation concentrate yielded a molybdenum concentrate with a Mo grade of 40.23% and a Mo recovery rate of 75.96%, and a bismuth concentrate with a Bi grade of 29.32% and a Bi recovery rate of 70.51%. Copper was not recovered.

[0088] In summary, the mineral processing method of this invention features improved coarse grinding fineness, early recovery, energy efficiency, selective grinding and liberation, and high recovery rate. Compared with conventional molybdenum-bismuth-sulfur full flotation or equal-flotation-mixed flotation processes, the recovery rates of molybdenum, bismuth, and sulfur can be increased by 9-12 percentage points, 8-10 percentage points, and 12-15 percentage points, respectively, with a significant improvement in concentrate quality. This process addresses the complex intergrowth relationships and uneven particle size distribution of minerals in low-grade, complex, and difficult-to-process molybdenum-bismuth-sulfur polymetallic ores. It fully utilizes the differences in liberation degree and floatability among different sulfide minerals, prioritizing the recovery of more fully liberated sulfide minerals. After appropriate enhanced flotation enrichment of intergrowth sulfide minerals, a selective grinding-preferential separation recovery process is employed. This significantly improves the liberation degree of the target minerals while effectively preventing over-grinding, resulting in significantly improved molybdenum and bismuth concentrate quality and recovery rates. This provides a new approach and strategy for the recovery and utilization of this type of low-grade, complex, and difficult-to-process polymetallic sulfide ores.

Claims

1. A mineral processing method for efficient recovery of low-grade molybdenum-bismuth-sulfur polymetallic ores through flotation, characterized in that, Includes the following steps: (1) The raw ore of low-grade molybdenum-bismuth-sulfur polymetallic ore is crushed, ground and classified, and then fed into a mixing tank to prepare slurry to obtain ore feed slurry. (2) The ore slurry obtained in step (1) is subjected to full flotation roughing of sulfide ore to obtain full flotation rough concentrate and full flotation roughing tailings; (3) The fully floated rough concentrate obtained in step (2) is subjected to full float cleaning to obtain fully floated concentrate and fully floated middlings. The fully floated concentrate is used as feed for subsequent molybdenum-bismuth-sulfur separation operations. (4) The full flotation roughing tailings obtained in step (2) are subjected to full flotation scavenging to obtain full flotation scavenging concentrate and flotation tailings; (5) Mix the full flotation scavenging concentrate obtained in step (4) with the full flotation middlings obtained in step (3) and perform flotation scavenging to obtain scavenging concentrate and scavenging middlings. The scavenging middlings are returned to the full flotation roughing and re-selection in step (2). (6) Grind the scavenged concentrate obtained in step (5) to obtain fine grinding slurry, and return the fine grinding slurry to step (3) for full flotation and re-selection; (7) The full flotation concentrate obtained in step (3) is subjected to molybdenum-bismuth flotation desulfurization to obtain molybdenum-bismuth mixed concentrate and sulfur concentrate; (8) The molybdenum-bismuth mixed concentrate obtained in step (7) is subjected to bismuth-copper flotation separation to obtain molybdenum concentrate and bismuth-copper mixed concentrate; (9) Separate bismuth and copper from the bismuth-copper mixed concentrate obtained in step (8) to obtain bismuth concentrate and copper concentrate.

2. The mineral processing method according to claim 1, characterized in that, In step (1), the raw ore of the low-grade molybdenum-bismuth-sulfur polymetallic ore includes bismuthite, molybdenite, pyrite, pyrrhotite and chalcopyrite; the raw ore contains 0.05%-0.5% Bi, 0.02%-0.5% Mo, 0.5%-8% S and 0.01%-0.05% Cu.

3. The mineral processing method according to claim 2, characterized in that, The molybdenite, bismuthite, and chalcopyrite in the raw ore of the low-grade molybdenum-bismuth-sulfur polymetallic ore have a grain size distribution of 0.005–0.15 mm.

4. The mineral processing method according to any one of claims 1 to 3, characterized in that, In step (1), the fineness of the slurry after grinding and classification of the raw ore is 50% to 80% -0.075 mm.

5. The mineral processing method according to any one of claims 1 to 3, characterized in that, In step (1), the mass concentration of the slurry after conditioning is 30% to 65%.

6. The mineral processing method according to any one of claims 1 to 3, characterized in that, In steps (2), (3), (4), and (5), the modifiers used in the full flotation roughing, full flotation cleaning, full flotation scavenging, and flotation scavenging of the sulfide ore are selected from any one or a combination of sodium carbonate, water glass, sodium humate, copper sulfate, lead nitrate, and sodium hexametaphosphate, and the collectors used are selected from any one or a combination of non-polar oils, xanthates, sulfur-nitrogen compounds, thioamine esters, and thiols.

7. The mineral processing method according to any one of claims 1 to 3, characterized in that, In step (6), the fineness of the grinding is ≥90% of the -200 mesh particle size, and the grinding equipment is an abrasive mill or a vertical mill.

8. The mineral processing method according to any one of claims 1 to 3, characterized in that, In step (7), the flotation process for molybdenum-bismuth flotation desulfurization consists of one roughing, three cleaning, and three scavenging stages. The modifier used is selected from one or a combination of activated carbon, lime, mercapto compounds, sodium cyanate, acetone cyanohydrin, water glass, and sodium hexametaphosphate. The collector used is selected from any one or a combination of non-polar oils, xanthates, sulfur-nitrogen compounds, and thiols.

9. The mineral processing method according to any one of claims 1 to 3, characterized in that, In step (8), the flotation process for separating bismuth-suppressed copper and molybdenum consists of one roughing, five cleaning, and three scavenging processes. The modifier used is selected from one or a combination of sodium sulfide, water glass, sodium hexametaphosphate, mercapto compounds, sodium sulfite, and sodium humate. The collector used is selected from any one or a combination of nonpolar oils, xanthates, sulfur-nitrogen compounds, and thiols.

10. The mineral processing method according to any one of claims 1 to 3, characterized in that, In step (9), the bismuth-copper separation flotation process consists of one roughing, two cleaning, and one scavenging. The modifier used is selected from any one or a combination of several of water glass, copper sulfate, sodium hexametaphosphate, sodium sulfite, and sodium sulfide. The collector used is selected from any one or a combination of several of xanthates, sulfur nitrogen compounds, thioamine esters, and thiols.

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