Method for recovering copper and sulfur in low-grade copper-molybdenum ore

Abstract

The invention provides a method for recovering copper and sulfur in low-grade copper-molybdenum ore, which comprises the following steps: crushing and grinding raw ore, carrying out copper-molybdenum mixed roughing, separating molybdenum ore from part of copper ore in the raw ore, separating the copper ore from the molybdenum ore through flotation operation of copper-molybdenum separation, and obtaining molybdenum concentrate and copper concentrate I; and flotation is conducted on tailings obtained after copper and molybdenum mixed roughing, and copper concentrate II and sulfur concentrate are obtained finally. According to the method, by the adoption of the technological process of preferentially recovering copper and then separating copper and sulfur to recover copper and sulfur products, segmented recovery of low-grade copper is achieved, meanwhile, comprehensive recovery of sulfur is also achieved, the mode that copper and molybdenum are separated firstly and then copper and sulfur are separated can reduce interference of sulfur ore in the copper-molybdenum separation process, and meanwhile the situation that sulfur ore is separated in the copper-sulfur separation process can be reduced. Therefore, mutual inclusion among the ores is reduced, the separation efficiency is improved, meanwhile, the ores are comprehensively recovered, and the method has the characteristic of reducing resource waste.

Description

Technical Field

[0001] The present application relates to mineral flotation technology, and in particular to a method for recovering copper and sulfur from low-grade copper-molybdenum ore. Background Art

[0002] High-quality mineral materials such as copper and molybdenum resources have been widely used in the development of the world. Copper in nature generally exists in the form of compounds, and only a few are produced in the form of natural copper. So far, more than 280 types of copper minerals have been discovered. The occurrence types of copper minerals are extremely complex, and can be roughly divided into three categories: copper sulfide minerals, copper oxide minerals, and natural copper. Among them, because copper is very easy to react with sulfur to form sulfide minerals in its natural state, it mainly occurs in the form of sulfide minerals. Among the copper sulfide minerals, the most industrially valuable mineral is chalcopyrite, which accounts for about two-thirds of the total reserves of copper minerals.

[0003] Molybdenum has never been found in its natural or free state. Among the more than 30 molybdenum minerals that have been identified, molybdenum sulfide minerals, molybdenum oxide minerals, molybdenate and other molybdenum-containing salts are its main occurrence forms. Molybdenum-containing ores usually include molybdenite (MoS2), calcium molybdate ore (CaMoO4), lead molybdenite (PbMoO4), calcium molybdenite (Ca[Mo, W]O4), iron molybdenum fluorite (Fe2[MoO4]3·7H2O) and blue molybdenite (Mo3O8·nH2O), but the most widely distributed and most economically valuable one is molybdenite in the form of sulfide.

[0004] Molybdenite and chalcopyrite are both common sulfide minerals in nature, usually closely coexisting in copper-molybdenum ores. With the increase in mining years in recent years, copper-molybdenum ores are facing problems such as more lean ores, fine embedded particles, complex associated conditions, low metal grades, and difficult ore selection in major selection plants. And because molybdenite and chalcopyrite are both sulfide minerals, the recovery of sulfur ores in their coexisting ores should also be paid attention to. Summary of the invention

[0005] The present application provides a method for recovering copper and sulfur in low-grade copper-molybdenum ores, which is used to provide a method for recovering copper and sulfur in copper-molybdenum ores which currently have a large number of lean ores, fine embedded particles, complex associated conditions and low metal grades.

[0006] The present application provides a method for recovering copper and sulfur from low-grade copper-molybdenum ore, comprising the following steps:

[0007] a) crushing the copper-molybdenum ore and grinding it to obtain ore pulp;

[0008] b) subjecting the raw ore pulp to mixed roughing of copper and molybdenum to obtain roughing copper-molybdenum concentrate and scavenging copper-molybdenum concentrate;

[0009] c) mixing the roughing copper-molybdenum concentrate and the scavenging copper-molybdenum concentrate, and adding a copper depressant to carry out a copper-molybdenum separation flotation to obtain a molybdenum concentrate and molybdenum tailings;

[0010] D) the selected molybdenum tailings are subjected to copper ore flotation to obtain copper concentrate I and selected copper tailings;

[0011] e) subjecting the scavenged tailings of the copper-molybdenum mixed roughing to copper-sulfur mixed roughing to obtain copper-sulfur mixed roughing tailings and copper-sulfur mixed roughing concentrate;

[0012] f) adding lime to the copper-sulfur mixed rougher concentrate and then regrinding the concentrate to obtain a copper-sulfur mixed ore slurry;

[0013] g) subjecting the copper-sulfur mixed ore pulp to copper-sulfur separation flotation to obtain copper concentrate II and sulfur crude ore, wherein the pH value of the pulp during the copper-sulfur separation flotation process is 8 to 8.5;

[0014] h) flotation the sulfur ore to obtain sulfur concentrate and tailings II.

[0015] The method for recovering copper and sulfur from low-grade copper-molybdenum ore provided in the present application has the following beneficial effects:

[0016] 1) A process flow of first recovering copper and then separating copper and sulfur to recover copper and sulfur products is adopted to achieve segmented recovery of low-grade copper and comprehensive recovery of sulfur. This method of first separating copper and molybdenum and then separating copper and sulfur can reduce the interference of sulfur ore in the copper-molybdenum separation process and also reduce the interference of molybdenum ore in the copper-sulfur separation process, thereby reducing the mutual inclusion between the ores and improving the separation efficiency. At the same time, the comprehensive recovery of various minerals can reduce the waste of resources.

[0017] 2) When separating copper and sulfur, a low alkalinity condition of pH 8 to 8.5 is used for separation, which has the characteristics of reducing the generation of alkaline wastewater and improving the separation degree of copper and sulfur.

[0018] 3) Before separating copper and sulfur, adding lime to the copper-sulfur mixed rougher concentrate and grinding the ore together can improve the distribution uniformity of lime in the slurry, which is more conducive to the combination of lime and sulfur ore, thereby enhancing the inhibition effect on sulfur ore and improving the separation efficiency of copper and sulfur.

[0019] Optionally, the copper-molybdenum mixed roughing in step b) adopts a mixed flotation process of one roughing and one scavenging;

[0020] In step b), a frother, a collector and an auxiliary agent are added to the raw ore pulp during the roughing process, the frother includes one or more of 2# oil, cresol oil, sodium alkyl sulfate and polyethylene glycol ether, the collector includes one or more of xanthate, isopropyl xanthate, butyl xanthate, ethyl xanthate, isobutyl xanthate and black medicine, and the auxiliary agent includes kerosene and / or diesel;

[0021] The amount of foaming agent used is 20-30g / t

[0022] The amount of collector used is 60-80 g / t;

[0023] The dosage of additives is 50-80g / t;

[0024] During the scavenging process of step b), kerosene is also added in an amount of 10 to 20 g / t.

[0025] Optionally, in step c), the copper inhibitor comprises sodium thioglycolate and sodium sulfide;

[0026] The usage of sodium thioglycolate is 200-300g / t;

[0027] The usage of sodium sulfide is 100-150g / t.

[0028] Optionally, in step d), the copper ore flotation adopts a flotation process of a roughing selection, a cleaning selection, a scavenging selection, and sequential return of the intermediate ore;

[0029] In the roughing process in step d), copper sulfate and a collector are added to the molybdenum tailings, wherein the added collector includes Z200, and the amount used is 60-80 g / t;

[0030] In the scavenging process in step d), a collector including Z200 is also added, and the amount used is 60-80 g / t;

[0031] The dosage of copper sulfate is 50-100g / t.

[0032] Optionally, the copper-sulfur mixed roughing in step e) adopts a mixed flotation process of a roughing, a pre-concentration, and the pre-concentrated middlings are returned to the roughing;

[0033] In step e), a collector and a frother are added to the scavenged tailings of the copper-molybdenum mixed roughing process, wherein the collector comprises one or more of xanthate, isopropyl xanthate, butyl xanthate, ethyl xanthate, isobutyl xanthate and black medicine;

[0034] The foaming agent includes one or more of 2# oil, cresol oil, sodium alkyl sulfate, and polyethylene glycol ether;

[0035] The amount of collector used is 100-130 g / t;

[0036] The usage of foaming agent is 10-20g / t.

[0037] Optionally, the copper-sulfur separation flotation in step g) adopts a flotation process of one roughing selection, four cleaning selections, one scavenging selection, and sequential return of the middling ore;

[0038] In step g), a collector is added to the copper-sulfur mixed ore pulp during the roughing process, wherein the collector comprises FBC and YA, wherein the amount of FBC is 30-50 g / t, and the amount of YA is 300-400 g / t;

[0039] In step g), a collector including YA is also added during the first concentration, and the amount thereof is 100-200 g / t;

[0040] In step g), a collector including YA is also added in the second concentration, and the amount thereof is 50-100 g / t.

[0041] Optionally, in step h), the flotation of the sulfur ore adopts a flotation process of a roughing selection, a cleaning selection, a scavenging selection, and a sequential return of the middling ore;

[0042] In step h), sulfuric acid and a collector are added during the roughing process, wherein the added collector comprises one or more of xanthate, isopropyl xanthate, butyl xanthate, ethyl xanthate, isobutyl xanthate, and black medicine, and the amount of the collector is 60-90 g / t, and the amount of sulfuric acid is 2500-3000 g / t;

[0043] In step h), sulfuric acid is also added during the concentration process, and the amount used is 300-600 g / t.

[0044] Optionally, the concentration of the raw ore pulp is 40-45%, and the grinding fineness is -0.074mm≥50%;

[0045] The concentration of copper-sulfur mixed ore slurry is 20-25%, and the grinding fineness is -0.038mm≥80%;

[0046] In step f), the amount of lime added is 1000-1500 g / t.

[0047] Optionally, in step c), before the roughing copper-molybdenum concentrate and the scavenging copper-molybdenum concentrate are mixed and subjected to copper-molybdenum separation flotation, a pretreatment operation is further performed, including:

[0048] The mixed roughing copper-molybdenum concentrate and scavenging copper-molybdenum concentrate are sent to a cyclone for cyclone classification, and the overflow of the cyclone is used for copper-molybdenum separation flotation;

[0049] The cyclone bottom flow enters the mill for grinding to obtain pre-treated mixed ore pulp, which is then returned to the cyclone for cyclone classification.

[0050] The fineness of the pre-treated mixed slurry is -0.038mm≥60%, and the concentration is 25-30%.

[0051] Optionally, in step g), during the copper-sulfur separation flotation process, the copper tailings and the middlings after roughing are combined for scavenging to obtain rough sulfur ore. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0053] Figure 1 A flow chart of a method for recovering copper and sulfur from low-grade copper-molybdenum ore provided in one embodiment of the present application. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work also fall within the scope of protection of the present application.

[0055] like Figure 1 As shown, the present application provides a method for recovering copper and sulfur from low-grade copper-molybdenum ore, comprising the following steps:

[0056] a) crushing the copper-molybdenum ore and grinding it to obtain ore pulp; the concentration of the ore pulp is 40-45%, and the grinding fineness is -0.074mm≥50%.

[0057] In the present application, the grinding fineness is controlled at the order of -0.074mm≥50%, and the fineness of 0.074mm is a relatively coarse particle size, and the raw ore is a sulfide ore containing molybdenum, copper, iron and sulfur, wherein molybdenum mainly exists in the form of molybdenite (MoS2), and copper mainly exists in the form of chalcopyrite (CuFeS2), wherein sulfur ore and other associated metal sulfide ores are embedded. Under this particle size, the dissociation degree of copper ore, molybdenum ore and sulfur ore is moderate, which enables these large particles of metal ore to be captured preferentially in the subsequent roughing process of copper-molybdenum mixed selection, avoiding the disadvantages of too low slurry fineness, excessive dissociation of metal ore, resulting in metal ion loss, and the inevitable high ion in the subsequent selection process, which has an adverse effect on flotation.

[0058] b) subjecting the raw ore pulp to mixed copper-molybdenum roughing to obtain roughing copper-molybdenum concentrate and scavenging copper-molybdenum concentrate; the mixed copper-molybdenum roughing adopts a mixed flotation process of one roughing and one scavenging; during the roughing process, a frother, a collector and an auxiliary agent are added to the raw ore pulp, the frother comprising one or more of 2# oil, cresol oil, sodium alkyl sulfate and polyethylene glycol ether, the collector comprising one or more of xanthate, isopropyl xanthate, butyl xanthate, ethyl xanthate, isobutyl xanthate and black medicine, and the auxiliary agent comprising kerosene and / or diesel.

[0059] In the present application, the collector, frother and auxiliary agent mentioned above are used to make the molybdenum ore and copper ore in the ore pulp float up for easy capture. In the present application, the frother used is 2# oil, the collector is FBC, and the auxiliary agent is kerosene, wherein FBC can selectively adhere to the surface of the copper ore, and the molybdenum ore has natural floatability, and its floatability can be further enhanced under the selective attachment of the auxiliary kerosene. The combined use of the above-mentioned agents can preferentially enrich the molybdenum ore and a part of the chalcopyrite in the original ore pulp, and separate them from the original ore pulp under the action of the frother. Therefore, the molybdenum ore and a part of the copper ore can be preferentially floated out after the copper-molybdenum mixed roughing, thereby reducing the influence of the molybdenum ore on the subsequent copper and sulfur separation.

[0060] c) mixing the roughing copper-molybdenum concentrate and the scavenging copper-molybdenum concentrate, and adding a copper depressant to carry out a copper-molybdenum separation flotation to obtain a molybdenum concentrate and molybdenum tailings;

[0061] In the present application, since the copper and molybdenum are separated in advance by flotation, the surfaces of the separated copper and molybdenum ores contain collectors or additives that can make them float. Therefore, when separating copper and molybdenum, the collectors on the surface of the minerals should be removed. There are many methods for removing the agents, such as water washing, grinding, concentration, etc. In the present application, the method of grinding for removal of the agents is adopted, that is, the agents on the surface of the ore particles are removed by grinding before the copper and molybdenum are separated.

[0062] In the flotation of copper and molybdenum separation, due to the natural floatability of molybdenum ore, the present application adopts the method of suppressing copper and floating molybdenum to separate copper and molybdenum ore. Therefore, a copper inhibitor is added to increase the hydrophilicity of the copper ore and suppress the floating of the copper ore, thereby achieving the separation of copper and molybdenum ore.

[0063] d) The molybdenum tailings are subjected to copper flotation to obtain copper concentrate I and copper tailings; the copper flotation adopts a flotation process of one roughing selection, one cleaning selection, one scavenging selection, and the intermediate ore is returned in sequence.

[0064] In the present application, molybdenum tailings, i.e., ore particles mainly composed of copper ore, are selected. In the copper ore flotation process, the copper ore is mainly enriched and floated. Since the addition of copper inhibitors reduces the floatability of copper ore during the copper-molybdenum separation process, it is necessary to eliminate the inhibition of copper inhibitors on copper ore during the copper ore flotation process and activate the copper ore. The activator used in the present application is copper sulfate, which can activate copper ore and will not introduce metal ions that have adverse effects on the flotation agent.

[0065] e) subjecting the scavenging tailings of the copper-molybdenum mixed roughing to copper-sulfur mixed roughing to obtain copper-sulfur mixed roughing tailings and copper-sulfur mixed roughing concentrate; the copper-sulfur mixed roughing adopts a mixed flotation process of a roughing, a pre-concentration, and the pre-concentrated middlings are returned to the roughing; wherein a collector and a frother are added to the scavenging tailings of the copper-molybdenum mixed roughing during the roughing process.

[0066] In the present application, the purpose of the copper-sulfur mixed roughing is to enrich and separate copper ore and sulfur ore from the scavenging tailings of the copper-molybdenum mixed roughing. Because the copper ore exists in the tailings in the form of chalcopyrite, the collector is a xanthate collector, which can selectively combine with the sulfur in the chalcopyrite and sulfur ore, thereby capturing the chalcopyrite and sulfur ore, and then with the aid of a frother, the chalcopyrite and sulfur ore can be adhered to the surface of the bubbles in the flotation process and float up, thereby realizing the separation of the chalcopyrite, sulfur ore and other gangue or ores.

[0067] The purpose of pre-concentration is to further enrich the copper and sulfur mixed ore obtained in the copper and sulfur mixed roughing process and reduce the content of other miscellaneous ores in the copper and sulfur mixed ore.

[0068] f) adding lime to the copper-sulfur mixed rougher concentrate and then regrinding to obtain copper-sulfur mixed ore slurry; the concentration of the copper-sulfur mixed ore slurry is 20-25%, the grinding fineness is -0.038mm≥80%; the amount of lime added is 1000-1500g / t.

[0069] In the present application, the purpose of regrinding is to obtain ore particles with grinding fineness that meets the requirements, and to remove the collector on the surface of the ore particles, which is convenient for the subsequent separation of copper and sulfur. In the regrinding process, lime is added to the copper and sulfur mixed ore for grinding together, which can make the lime (CaO) and the sulfur ore contact and react more fully, improve the hydrophilicity of the sulfur ore, and thus better suppress the sulfur ore.

[0070] In the present application, because the copper ore mainly exists in the form of chalcopyrite, it is more closely embedded with the sulfur ore. The copper-sulfur mixed ore is re-ground to make the grinding fineness reach the order of -0.038mm≥80%. The slurry of this fineness can enhance the dissociation degree of copper and sulfur ore, thereby facilitating the reduction of the mutual inclusion of copper and sulfur, and facilitating the separation of copper and sulfur. Moreover, this method can also reduce the amount of lime used, and can separate copper and sulfur under low alkalinity conditions, which has the characteristics of reducing alkali pollution and saving lime use.

[0071] g) The copper-sulfur mixed ore pulp is subjected to copper-sulfur separation flotation to obtain copper concentrate II and sulfur rough ore. The pH of the pulp during the copper-sulfur separation flotation process is 8-8.5; the copper-sulfur separation flotation adopts a flotation process of one roughing selection, four cleaning selections, one scavenging selection, and sequential return of the intermediate ore; during the roughing selection process, collectors are added to the copper-sulfur mixed ore pulp, and the collectors include FBC and YA.

[0072] In the present application, FBC (FBC is a branched alcohol) can selectively adsorb on the surface of copper ore to improve the floatability of copper ore; pyrite is often associated with chalcopyrite, and pyrite is easily inhibited under conditions of high alkalinity (pH greater than 12), but high alkalinity often requires the addition of a large amount of lime or the use of a strong base, which will result in the amount of acid used in subsequent neutralization, and will also produce a large amount of difficult-to-treat high-salinity wastewater, which is detrimental to the environment. The YA collector used in the present application is a cationic surfactant that can selectively adsorb with pyrite (that is, it is a selective inhibitor of pyrite), thereby improving the hydrophilicity of pyrite to achieve the purpose of inhibiting pyrite. Therefore, the YA collector and lime can work together to not only reduce the amount of lime used, but also improve the inhibition efficiency of sulfide (pyrite is included in sulfide).

[0073] In another achievable manner, hydroxymethyl cellulose is further added during the roughing process of copper-sulfur separation flotation, wherein the amount of hydroxymethyl cellulose added is 100-200 g / t. Its specific role is that the lime added during the regrinding process can be fully mixed with the ore particles during the grinding process (in the present application, due to the characteristics of sulfur ore being acidic and lime being alkaline, the acid-base neutralization reaction between the two during the grinding process can enable the lime to selectively combine with the sulfur ore, and because the ore particles are further ground during the regrinding process, the degree of dissociation between the copper ore and the sulfur ore is increased, that is, the mutual inclusion between the sulfur ore and the copper ore is reduced, so the addition of lime will selectively combine with the acidic sulfur ore), and the calcium in the lime, that is, calcium oxide, is a divalent multivalent ion. After combining with the sulfur ore, the calcium ion will be adsorbed on the surface of the sulfur ore, so that the surface of the sulfur ore has a positive charge, and the hydroxymethyl cellulose has a negative charge after being added (hydrolysis, etc. forms negatively charged particles). The electrical attraction between the two allows the hydroxymethyl cellulose to be adsorbed on the surface of the sulfur ore. In this process, calcium plays the role of a "bridge" to connect the sulfur ore and the hydroxymethyl cellulose, and the hydrophilic property of the hydroxymethyl cellulose strengthens the affinity of the sulfur ore with water, thereby enhancing the inhibitory effect on the sulfur ore.

[0074] h) The sulfur ore is subjected to sulfur flotation to obtain sulfur concentrate and tailings II; the sulfur ore flotation adopts a flotation process of roughing, cleaning, scavenging and sequential return of the intermediate ore, and sulfuric acid and collectors are added during the roughing process.

[0075] In the present application, sulfur ore flotation is the process of enriching and separating sulfur ore. Since alkaline lime is added to inhibit sulfur ore during copper and sulfur separation, sulfur ore needs to be activated during flotation. Sulfuric acid is added to neutralize the lime on the surface of the sulfur ore and restore the floatability of the sulfur ore. The collector adopts a xanthate collector, which can selectively combine with the sulfur ore so that the sulfur ore adheres to the bubbling surface during the flotation process and is captured.

[0076] In the present application, sulfuric acid is added to adjust the pH of the slurry to 4-5, thereby activating the sulfur ore.

[0077] In this application, the quality of each mine obtained is as follows:

[0078] Copper grade in molybdenum concentrate: ≤0.5%; copper grade in copper concentrate I: ≥22%; copper grade in copper concentrate II: ≥18%; sulfur concentrate grade: ≥45%; copper grade in tailings I: ≤0.015%; copper grade in tailings II ≤0.1%; copper recovery rate ≥60%; sulfur recovery rate ≥30%.

[0079] The method for recovering copper and sulfur from low-grade copper-molybdenum ore provided in the present application has the following beneficial effects:

[0080] 1) A process flow of first recovering copper and then separating copper and sulfur to recover copper and sulfur products is adopted to achieve segmented recovery of low-grade copper and comprehensive recovery of sulfur. This method of first separating copper and molybdenum and then separating copper and sulfur can reduce the interference of sulfur ore in the copper-molybdenum separation process, and can also reduce the interference of molybdenum ore in the copper-sulfur separation process, thereby reducing the mutual inclusion between the ores, improving the separation efficiency and the grade of the concentrate, and at the same time, the comprehensive recovery of various minerals can reduce the waste of resources.

[0081] 2) When separating copper and sulfur, a low alkalinity condition of pH 8 to 8.5 is used for separation, which has the characteristics of reducing the generation of alkaline wastewater and improving the separation degree of copper and sulfur.

[0082] 3) Before separating copper and sulfur, adding lime to the copper-sulfur mixed rougher concentrate and grinding the ore together can improve the distribution uniformity of lime in the slurry, which is more conducive to the combination of lime and sulfur ore, thereby enhancing the inhibition effect on sulfur ore and improving the separation efficiency of copper and sulfur.

[0083] Optionally, in step b), the amount of the foaming agent used is 20 to 30 g / t;

[0084] The amount of collector used is 60-80g / t; the amount of auxiliary agent used is 50-80g / t;

[0085] During the scavenging process of step b), kerosene is also added in an amount of 10 to 20 g / t.

[0086] In the present application, kerosene is also added during the scavenging process of step b) to capture and float the molybdenum ore in the tailings.

[0087] Optionally, in step c), the copper inhibitor comprises sodium thioglycolate and sodium sulfide;

[0088] The usage of sodium thioglycolate is 200-300g / t;

[0089] The usage of sodium sulfide is 100-150g / t.

[0090] In the present application, sodium thioglycolate and sodium sulfide can be selectively combined with copper ore to enhance the hydrophilicity of copper ore and inhibit copper ore. Because sodium sulfide is easily oxidized, the combination of sodium thioglycolate and sodium sulfide can reduce the amount of sodium sulfide used and reduce the oxidation of sodium sulfide, thereby enhancing the inhibitory effect on copper ore.

[0091] Optionally, copper sulfate and a collector are added to the molybdenum tailings during the roughing process in step d), and the added collector includes Z200, and the amount used is 60-80 g / t;

[0092] In the scavenging process in step d), a collector including Z200 is also added, and the amount used is 60-80 g / t;

[0093] The dosage of copper sulfate is 50-100g / t.

[0094] In the present application, copper sulfate is an activator of copper ore. The addition of copper sulfate can remove inhibitors (such as sodium thioglycolate and sodium sulfide) on the surface of copper ore, thereby restoring the floatability of copper ore and facilitating adsorption by the collector.

[0095] Optionally, in step e), the collector includes one or more of xanthate, isopropyl xanthate, butyl xanthate, ethyl xanthate, isobutyl xanthate, and black medicine;

[0096] The foaming agent includes one or more of 2# oil, cresol oil, sodium alkyl sulfate, and polyethylene glycol ether;

[0097] The amount of collector used is 100-130 g / t;

[0098] The usage of foaming agent is 10-20g / t.

[0099] In the present application, the collector is a xanthate, which can selectively combine with copper ore to capture the copper ore; the role of the frother is to produce dense and stable bubbles after aeration, so that the buoyant mineral particles adhere to the bubbles and float to achieve flotation.

[0100] Optionally, in step g), the amount of FBC is 30-50 g / t, and the amount of YA is 300-400 g / t;

[0101] In step g), a collector including YA is also added during the first concentration, and the amount thereof is 100-200 g / t;

[0102] In step g), a collector including YA is also added in the second concentration, and the amount thereof is 50-100 g / t.

[0103] Optionally, in step h), sulfuric acid and a collector are added during the roughing process, the added collector includes one or more of xanthate, isopropyl xanthate, butyl xanthate, ethyl xanthate, isobutyl xanthate, and black medicine, and the amount of the collector is 60-90 g / t, and the amount of sulfuric acid is 2500-3000 g / t;

[0104] In step h), sulfuric acid is also added during the concentration process, and the amount used is 300-600 g / t.

[0105] Optionally, in step c), before the roughing copper-molybdenum concentrate and the scavenging copper-molybdenum concentrate are mixed and subjected to copper-molybdenum separation flotation, a pretreatment operation is further performed, including:

[0106] The mixed roughing copper-molybdenum concentrate and scavenging copper-molybdenum concentrate are sent to a cyclone for cyclone classification, and the overflow of the cyclone is used for copper-molybdenum separation flotation;

[0107] The cyclone bottom flow enters the mill for grinding to obtain pre-treated mixed ore pulp, which is then returned to the cyclone for cyclone classification.

[0108] The fineness of the pre-treated mixed ore pulp is -0.038mm≥60%, and the concentration is 25-30%.

[0109] In this application, the method of flotation and grinding of the mixed rough copper-molybdenum concentrate and scavenged copper-molybdenum concentrate can avoid over-grinding of fine particles in the mixed ore, resulting in excessive dissociation of the ore and loss. Grinding can not only achieve the purpose of drug removal, but also the fineness of the pre-treated mixed slurry in this application is -0.038mm≥60%, which can also improve the separation of copper ore and molybdenum ore and reduce the mutual inclusion of copper and molybdenum.

[0110] The concentration of the pre-treated mixed slurry is 25-30%. This low-concentration slurry is conducive to the ore particles (molybdenum ore in this application) fully contacting with the bubbles during flotation and floating up. This relatively low-concentration slurry can also reduce the probability of copper ore floating in the slurry, which is conducive to the separation of copper and molybdenum ores.

[0111] Optionally, in step g), during the copper-sulfur separation flotation process, the copper tailings and the middlings after roughing are combined for scavenging to obtain rough sulfur ore.

[0112] In the present application, the copper tailings and the middlings after roughing are combined for scavenging to obtain sulfur coarse ore, which can reduce the output of tailings, reduce the waste of mineral resources, and also improve the recovery rate of copper concentrate and sulfur concentrate. Specific embodiments

[0114] Example 1

[0115] A method for recovering copper and sulfur from low-grade copper-molybdenum ore is as follows:

[0116] S101, crushing the copper-molybdenum ore and grinding it to obtain ore pulp with a concentration of 40% and a grinding fineness of -0.074mm≥50%.

[0117] S102, using a mixed flotation process of one roughing and one scavenging to carry out mixed roughing of copper and molybdenum on the raw ore pulp to obtain a roughing copper-molybdenum concentrate and a scavenging copper-molybdenum concentrate;

[0118] During the roughing process, 20 g / t of 2# oil, 60 g / t of FBC and 50 g / t of kerosene were added to the raw ore pulp;

[0119] 10g / t kerosene is added during the scavenging process.

[0120] S103, mixing the roughing copper-molybdenum concentrate and the scavenging copper-molybdenum concentrate, and sending them to a cyclone for cyclone classification, and the overflow of the cyclone is used for copper-molybdenum separation and flotation; the underflow of the cyclone enters a mill for grinding to obtain a pre-treated mixed slurry with a fineness of -0.038mm≥60% and a concentration of 25%, and the pre-treated mixed slurry is returned to the cyclone for cyclone classification;

[0121] In the copper-molybdenum separation flotation, sodium thioglycolate and sodium sulfide are added to the slurry obtained from the overflow of the cyclone to carry out a copper-molybdenum separation flotation to obtain molybdenum concentrate and molybdenum tailings;

[0122] The usage of sodium thioglycolate is 200-300g / t; the usage of sodium sulfide is 100g / t.

[0123] S104, flotation of the molybdenum tailings with a flotation process of roughing, cleaning, scavenging, and sequential return of the intermediate ore to flotate the copper ore to obtain copper concentrate I and copper tailings;

[0124] During the roughing process, 50 g / t of copper sulfate and 60 g / t of collector Z200 were added to the molybdenum tailings;

[0125] 60g / t Z200 is added during the scavenging process.

[0126] S105, the scavenging tailings of the copper-molybdenum mixed roughing are subjected to a mixed flotation process of a roughing, a pre-concentration, and the pre-concentrated middlings are returned to the roughing; copper-sulfur mixed roughing is performed to obtain copper-sulfur mixed roughing tailings and copper-sulfur mixed roughing concentrate;

[0127] During the roughing process, xanthate and 2# oil are added to the scavenging tailings of the copper-molybdenum mixed roughing;

[0128] The usage of xanthate is 100g / t; the usage of 2# oil is 10g / t.

[0129] S106, adding lime to the copper-sulfur mixed rougher concentrate and then regrinding to obtain a copper-sulfur mixed ore slurry with a concentration of 20% and a grinding fineness of -0.038 mm ≥ 80%;

[0130] The amount of lime added is 1000g / t.

[0131] S107, subjecting the copper-sulfur mixed ore pulp to flotation separation of copper and sulfur by a flotation process of first roughing, fourth cleaning, first scavenging, and sequential return of the intermediate ore, to obtain copper concentrate II and sulfur rough ore, wherein the pH of the pulp during the copper-sulfur separation flotation process is 8 to 8.5;

[0132] During the roughing process, FBC and YA are added to the copper-sulfur mixed ore pulp, wherein the amount of FBC is 30g / t and the amount of YA is 300g / t;

[0133] YA is added in the first concentration, and its dosage is 100g / t;

[0134] YA is added in the second concentration, and its dosage is 50g / t;

[0135] During the scavenging process, the copper tailings and the middlings after roughing are combined for scavenging to obtain the sulfur coarse ore.

[0136] S108, flotation of the sulfur ore by a flotation process of roughing, cleaning, scavenging, and sequential return of the intermediate ore to obtain sulfur concentrate and tailings II;

[0137] Sulfuric acid and xanthate are added during the roughing process, with the amount of xanthate being 60 g / t and the amount of sulfuric acid being 2500 g / t.

[0138] Sulfuric acid is added during the concentrating process, with the usage amount being 300g / t.

[0139] Example 2

[0140] A method for recovering copper and sulfur from low-grade copper-molybdenum ore is as follows:

[0141] S201, crushing the copper-molybdenum ore and grinding it to obtain ore pulp with a concentration of 45% and a grinding fineness of -0.074mm≥50%.

[0142] S202, using a mixed flotation process of one roughing and one scavenging to carry out mixed roughing of copper and molybdenum on the raw ore pulp to obtain a roughing copper-molybdenum concentrate and a scavenging copper-molybdenum concentrate;

[0143] During the roughing process, 30 g / t of 2# oil, 80 g / t of FBC and 80 g / t of kerosene were added to the raw ore pulp;

[0144] 20g / t kerosene is added during the scavenging process.

[0145] S203, the roughing copper-molybdenum concentrate and the scavenging copper-molybdenum concentrate are mixed and sent to a cyclone for cyclone classification, and the overflow of the cyclone is used for copper-molybdenum separation and flotation; the underflow of the cyclone enters a mill for grinding to obtain a pre-treated mixed slurry with a fineness of -0.038mm≥60% and a concentration of 30%, and the pre-treated mixed slurry is returned to the cyclone for cyclone classification;

[0146] In the copper-molybdenum separation flotation, sodium thioglycolate and sodium sulfide are added to the slurry obtained from the overflow of the cyclone to carry out a copper-molybdenum separation flotation to obtain molybdenum concentrate and molybdenum tailings;

[0147] The usage of sodium thioglycolate is 300g / t; the usage of sodium sulfide is 150g / t.

[0148] S204, flotation of the molybdenum tailings with a flotation process of roughing, cleaning, scavenging, and sequential return of the intermediate ore to flotate the copper ore to obtain copper concentrate I and copper tailings;

[0149] During the roughing process, 100 g / t of copper sulfate and 80 g / t of collector Z200 were added to the molybdenum tailings;

[0150] 80g / t Z200 is added during the scavenging process.

[0151] S205, the scavenging tailings of the copper-molybdenum mixed roughing are subjected to a mixed flotation process of a roughing, a pre-concentration, and the pre-concentrated middlings are returned to the roughing; copper-sulfur mixed roughing is performed to obtain copper-sulfur mixed roughing tailings and copper-sulfur mixed roughing concentrate;

[0152] During the roughing process, xanthate and 2# oil are added to the scavenging tailings of the copper-molybdenum mixed roughing;

[0153] The usage of xanthate is 130g / t; the usage of 2# oil is 20g / t.

[0154] S206, adding lime to the copper-sulfur mixed rougher concentrate and then regrinding to obtain a copper-sulfur mixed ore slurry with a concentration of 25% and a grinding fineness of -0.038 mm ≥ 80%;

[0155] The amount of lime added is 1500g / t.

[0156] S207, using a flotation process of first roughing, fourth cleaning, first scavenging, and sequential return of the intermediate ore to separate copper and sulfur from the copper-sulfur mixed ore pulp, to obtain copper concentrate II and sulfur rough ore, wherein the pH of the pulp during the copper-sulfur separation flotation process is 8-8.5;

[0157] During the roughing process, FBC and YA are added to the copper-sulfur mixed ore slurry, wherein the amount of FBC is 50g / t and the amount of YA is 400g / t;

[0158] YA is added in the first concentration, and its dosage is 200g / t;

[0159] YA is added in the second concentration, and its dosage is 100g / t;

[0160] During the scavenging process, the copper tailings and the middlings after roughing are combined for scavenging to obtain sulfur coarse ore.

[0161] S208, flotation of the sulfur ore by a flotation process of roughing, cleaning, scavenging, and sequential return of the intermediate ore to obtain sulfur concentrate and tailings II;

[0162] Sulfuric acid and xanthate are added during the roughing process, with the dosage of xanthate being 90 g / t and the dosage of sulfuric acid being 3000 g / t.

[0163] Sulfuric acid is added during the concentrating process, with the usage amount being 600g / t.

[0164] Example 3

[0165] A method for recovering copper and sulfur from low-grade copper-molybdenum ore is as follows:

[0166] S301, crushing the copper-molybdenum ore and grinding it to obtain ore pulp with a concentration of 43% and a grinding fineness of -0.074mm≥50%.

[0167] S302, using a mixed flotation process of one roughing and one scavenging to carry out mixed roughing of copper and molybdenum on the raw ore pulp to obtain a roughing copper-molybdenum concentrate and a scavenging copper-molybdenum concentrate;

[0168] During the roughing process, 25 g / t of 2# oil, 70 g / t of FBC and 70 g / t of kerosene were added to the raw ore pulp;

[0169] 15g / t kerosene is added during the scavenging process.

[0170] S303, the roughing copper-molybdenum concentrate and the scavenging copper-molybdenum concentrate are mixed and sent to a cyclone for cyclone classification, and the overflow of the cyclone is used for copper-molybdenum separation and flotation; the underflow of the cyclone enters a mill for grinding to obtain a pre-treated mixed slurry with a fineness of -0.038mm≥60% and a concentration of 28%, and the pre-treated mixed slurry is returned to the cyclone for cyclone classification;

[0171] In the copper-molybdenum separation flotation, sodium thioglycolate and sodium sulfide are added to the slurry obtained from the overflow of the cyclone to carry out a copper-molybdenum separation flotation to obtain molybdenum concentrate and molybdenum tailings;

[0172] The usage of sodium thioglycolate is 250g / t; the usage of sodium sulfide is 130g / t.

[0173] S304, flotation of the molybdenum tailings with a flotation process of roughing, cleaning, scavenging, and sequential return of the intermediate ore to flotate the copper ore to obtain copper concentrate I and copper tailings;

[0174] During the roughing process, 75 g / t of copper sulfate and 70 g / t of collector Z200 were added to the molybdenum tailings;

[0175] 70g / t Z200 was added during the scavenging process.

[0176] S305, the scavenging tailings of the copper-molybdenum mixed roughing are subjected to a mixed flotation process of a roughing, a pre-concentration, and the pre-concentrated middlings are returned to the roughing; copper-sulfur mixed roughing is performed to obtain copper-sulfur mixed roughing tailings and copper-sulfur mixed roughing concentrate;

[0177] During the roughing process, xanthate and 2# oil are added to the scavenging tailings of the copper-molybdenum mixed roughing;

[0178] The usage of xanthate is 115g / t; the usage of 2# oil is 15g / t.

[0179] S306, adding lime to the copper-sulfur mixed rougher concentrate and then regrinding to obtain a copper-sulfur mixed ore slurry with a concentration of 23% and a grinding fineness of -0.038 mm ≥ 80%;

[0180] The amount of lime added is 1250g / t.

[0181] S307, the copper-sulfur mixed ore pulp is subjected to a flotation process of first roughing, fourth cleaning, first scavenging, and sequential return of the intermediate ore to perform copper-sulfur separation flotation to obtain copper concentrate II and sulfur rough ore, and the pH of the pulp during the copper-sulfur separation flotation process is 8-8.5;

[0182] During the roughing process, FBC and YA are added to the copper-sulfur mixed ore slurry, wherein the amount of FBC is 40g / t and the amount of YA is 350g / t;

[0183] YA is added in the first concentration, and its dosage is 150g / t;

[0184] YA is added in the second concentration, and its dosage is 75g / t;

[0185] During the scavenging process, the copper tailings and the middlings after roughing are combined for scavenging to obtain sulfur coarse ore.

[0186] S308, flotation of the sulfur ore using a flotation process of roughing, cleaning, scavenging, and sequential return of the intermediate ore to obtain sulfur concentrate and tailings II;

[0187] Sulfuric acid and xanthate are added during the roughing process, with the amount of xanthate being 75 g / t and the amount of sulfuric acid being 2750 g / t.

[0188] Sulfuric acid is added during the concentrating process, with the usage amount being 450g / t.

[0189] Example 4

[0190] A method for recovering copper and sulfur from low-grade copper-molybdenum ore is as follows:

[0191] S401: Same operation as S301.

[0192] S402: Same operation as S302.

[0193] S403: Same operation as S303.

[0194] S404: Same operation as S304.

[0195] S405: Same operation as S305.

[0196] S406: Same operation as S306.

[0197] S407. The remaining operations are the same as S307, except that hydroxymethyl cellulose is added in the roughing process of copper-sulfur separation flotation, wherein the added amount of hydroxymethyl cellulose is 200 g / t.

[0198] S408: Same operation as S308.

[0199] Comparative Example 1

[0200] A method for recovering copper and sulfur from low-grade copper-molybdenum ore is as follows:

[0201] D101: Same operation as S301.

[0202] D102: Same operation as S302.

[0203] D103: Same operation as S303.

[0204] D104: Same operation as S304.

[0205] D105: Same operation as S305.

[0206] D106. The remaining operations are the same as S306, except that lime is not added during regrinding.

[0207] D107. The rest of the operations are the same as S307, except that 1250g / t of lime is added during the roughing process of copper-sulfur separation flotation.

[0208] D108: Same operation as S308.

[0209] Experimental example

[0210] In the following experiments, the FBC collector was purchased from Cangzhou Chengling Technology Co., Ltd., and the YA inhibitor was purchased from Beijing Ruibo New Resources Technology Co., Ltd.

[0211] The method of Example 3 was used to flotate a copper-molybdenum mine in Inner Mongolia. The copper grade of the raw ore used for the test was 0.032%, and the sulfur grade of the raw ore was 0.41%. The results are shown in Table 1:

[0212] Table 1

[0213]

[0214] The method of Example 3 was used to flotate a copper-molybdenum mine in Inner Mongolia. The copper grade of the raw ore used for the test was 0.035%, and the sulfur grade of the raw ore was 0.45%. The results are shown in Table 2:

[0215] Table 2

[0216]

[0217] The method of Example 4 was used to flotate a copper-molybdenum mine in Inner Mongolia. The copper grade of the raw ore used for the test was 0.032%, and the sulfur grade of the raw ore was 0.41%. The results are shown in Table 3:

[0218] Table 3

[0219]

[0220] From the comparison of the results in Table 3 and Table 1, it can be seen that the addition of hydroxymethyl cellulose during copper-sulfur separation can effectively improve the grade and recovery rate of copper concentrate II, and is also beneficial to the recovery of sulfur ore, and has a significant improvement on the grade and recovery rate of sulfur ore.

[0221] The method of Comparative Example 1 was used to flotate a copper-molybdenum mine in Inner Mongolia. The copper grade of the raw ore used for the test was 0.032%, and the sulfur grade of the raw ore was 0.41%. The results are shown in Table 4:

[0222] Table 4

[0223]

[0224] From the comparison of the results in Table 4 and Table 1, it can be seen that when lime is added during the roughing of copper-sulfur separation, the grades of the obtained copper concentrate II and sulfur concentrate are reduced, and the output of tailings II is increased. This shows that the flotation effect of adding lime during the roughing of copper-sulfur separation is lower than the effect of co-grinding and re-floating the mixed ore of lime and copper-sulfur.

[0225] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for recovering copper and sulfur from low-grade copper-molybdenum ore, characterized in that: The steps include: a) crushing the copper-molybdenum ore and grinding it to obtain ore pulp; b) subjecting the raw ore pulp to mixed roughing of copper and molybdenum to obtain roughing copper-molybdenum concentrate and scavenging copper-molybdenum concentrate; c) mixing the roughing copper-molybdenum concentrate and the scavenging copper-molybdenum concentrate, and adding a copper depressant to carry out a copper-molybdenum separation flotation to obtain a molybdenum concentrate and molybdenum tailings; D) the selected molybdenum tailings are subjected to copper ore flotation to obtain copper concentrate I and selected copper tailings; e) subjecting the scavenged tailings of the copper-molybdenum mixed roughing to copper-sulfur mixed roughing to obtain copper-sulfur mixed roughing tailings and copper-sulfur mixed roughing concentrate; f) adding lime to the copper-sulfur mixed rougher concentrate and then regrinding the concentrate to obtain a copper-sulfur mixed ore slurry; g) subjecting the copper-sulfur mixed ore pulp to copper-sulfur separation flotation to obtain copper concentrate II and sulfur crude ore, wherein the pH value of the pulp during the copper-sulfur separation flotation process is 8 to 8.5; h) flotation the sulfur ore to obtain sulfur concentrate and tailings II.

2. The method for recovering copper and sulfur from low-grade copper-molybdenum ore according to claim 1, characterized in that: In the step b), the mixed roughing of copper and molybdenum adopts a mixed flotation process of one roughing and one scavenging; In the step b), a frother, a collector and an auxiliary agent are added to the raw ore pulp during the roughing process, wherein the frother comprises one or more of 2# oil, cresol oil, sodium alkyl sulfate and polyethylene glycol ether, the collector comprises FBC, and the auxiliary agent comprises kerosene and / or diesel; The usage of the foaming agent is 20-30 g / t The usage amount of the collector is 60-80 g / t; The usage amount of the auxiliary agent is 50-80g / t; In the scavenging process of step b), kerosene is also added in an amount of 10 to 20 g / t.

3. The method for recovering copper and sulfur from low-grade copper-molybdenum ore according to claim 1, characterized in that: The copper inhibition in step c) comprises sodium thioglycolate and sodium sulfide; The usage of sodium thioglycolate is 200-300g / t; The usage of sodium sulfide is 100-150g / t.

4. The method for recovering copper and sulfur from low-grade copper-molybdenum ore according to claim 1, characterized in that: In the step d), the flotation of the copper ore adopts a flotation process of a roughing selection, a cleaning selection, a scavenging selection, and the intermediate ore is returned in sequence; In the roughing process in step d), copper sulfate and a collector are added to the molybdenum tailings, wherein the added collector includes Z200, and the amount used is 60-80 g / t; In the scavenging process in step d), a collector including Z200 is also added, and the amount used is 60-80 g / t; The dosage of copper sulfate is 50-100g / t.

5. The method for recovering copper and sulfur from low-grade copper-molybdenum ore according to claim 1, characterized in that: In the step e), the copper-sulfur mixed roughing separation adopts a mixed flotation process of a roughing separation, a pre-concentration, and the pre-concentrated middlings are returned to the roughing separation; In the step e), a collector and a frother are added to the scavenged tailings of the copper-molybdenum mixed roughing process, wherein the collector comprises one or more of xanthate, isopropyl xanthate, butyl xanthate, ethyl xanthate, isobutyl xanthate and black medicine; The foaming agent includes one or more of 2# oil, cresol oil, sodium alkyl sulfate, and polyethylene glycol ether; The usage amount of the collector is 100-130 g / t; The usage amount of the foaming agent is 10-20 g / t.

6. The method for recovering copper and sulfur from low-grade copper-molybdenum ore according to claim 1, characterized in that: In the step g), the copper-sulfur separation flotation adopts a flotation process of one roughing selection, four cleaning selections, one scavenging selection, and sequential return of the middling ore; In the step g), a collector is added to the copper-sulfur mixed ore pulp during the roughing process, wherein the collector comprises FBC and YA, wherein the amount of FBC is 30-50 g / t, and the amount of YA is 300-400 g / t; In the step g), a collector including YA is also added in the first concentration, and the amount thereof is 100-200 g / t; In the step g), a collector including YA is also added in the second concentration, and the amount thereof is 50-100 g / t.

7. The method for recovering copper and sulfur from low-grade copper-molybdenum ore according to claim 1, characterized in that: In the step h), the flotation of the sulfur ore adopts a flotation process of a roughing selection, a cleaning selection, a scavenging selection, and a sequential return of the intermediate ore; In the step h), sulfuric acid and a collector are added during the roughing process, wherein the added collector includes one or more of xanthate, isopropyl xanthate, butyl xanthate, ethyl xanthate, isobutyl xanthate, and black medicine, and the amount of the collector is 60-90 g / t, and the amount of sulfuric acid is 2500-3000 g / t; In the step h), sulfuric acid is also added during the concentration process, and the amount used is 300-600 g / t.

8. The method for recovering copper and sulfur from low-grade copper-molybdenum ore according to claim 1, characterized in that: The concentration of the raw ore pulp is 40-45%, and the grinding fineness is -0.074mm≥50%; The concentration of the copper-sulfur mixed ore slurry is 20-25%, and the grinding fineness is -0.038mm≥80%; The amount of lime added in step f) is 1000-1500 g / t.

9. The method for recovering copper and sulfur from low-grade copper-molybdenum ore according to claim 1, characterized in that: In the step c), before the roughing copper-molybdenum concentrate and the scavenging copper-molybdenum concentrate are mixed and subjected to copper-molybdenum separation flotation, a pretreatment operation is further performed, including: The mixed roughing copper-molybdenum concentrate and scavenging copper-molybdenum concentrate are sent to a cyclone for cyclone classification, and the overflow of the cyclone is used for copper-molybdenum separation flotation; The cyclone bottom flow enters the mill for grinding to obtain pre-treated mixed ore pulp, which is then returned to the cyclone for cyclone classification. The fineness of the pre-treated mixed ore pulp is -0.038mm≥60%, and the concentration is 25-30%.

10. The method for recovering copper and sulfur from low-grade copper-molybdenum ore according to any one of claims 1 to 9, characterized in that: In the step g), during the copper-sulfur separation flotation process, the copper tailings and the middlings after roughing are combined for scavenging to obtain rough sulfur ore.

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