Method for recovering valuable metals from copper slag and its application

Abstract

The present invention provides a method for recovering valuable metals in copper slag and its application. The method for recovering valuable metals in copper slag comprises the following steps: adding a composite depleting agent to hot copper slag at 1180-1320°C, slowly cooling the hot copper slag to room temperature, standing for more than 35 hours, and obtaining a self-pulverizing copper slag with a particle size of 1mm-10mm without traditional grinding; flotation of the self-pulverizing copper slag to further separate and recover metal sulfides, alloys and / or zinc ferrite; wherein the mass ratio of sodium sulfate to carbonaceous reducing agent in the composite depleting agent is 2-6:1; and the sulfur content in the composite depleting agent is 6-10 times the theoretical sulfur content required for all metal oxides in the copper slag to be fully sulfided. The present invention efficiently and cleanly realizes the stepwise recovery of valuable metals in copper slag, and has significant economic and environmental benefits.

Description

Technical Field

[0001] The invention relates to the field of copper slag treatment, and in particular to a method for recovering valuable metals in copper slag and application thereof. Background Art

[0002] Copper has excellent ductility, electrical conductivity and thermal conductivity, and is widely used in electricity, light industry, machinery, construction, national defense and other fields.

[0003] Copper slag is a product of the pyrometallurgical copper smelting process. For every ton of refined copper produced, about 2-3 tons of copper slag are discharged. The stacking of a large amount of copper slag requires the occupation of land or farmland, and its composition is complex, causing varying degrees of pollution to the surrounding environment. Copper slag contains a large number of available resources, and the main components of the phase are amorphous phase aggregates such as bornite, chalcocite, metallic copper, magnetite, fayalite, lead silicate, and iron silicate. With the promotion and application of modern oxygen-enriched enhanced smelting technology in the copper smelting process, the proportion of valuable metals lost in the oxidized state dissolved in silicates in the smelting slag has increased significantly, while traditional flotation can only have a significant recovery effect on mechanically included copper and iron sulfide particles, and cannot simultaneously recover oxidized copper; at the same time, in the existing copper mineral resources, heavy metals such as lead and zinc coexist with iron, which are impurities in the copper smelting process and are generally removed in the smelting slag. The existing copper slag recovery does not pay attention to the recovery of lead, zinc, and iron, resulting in a large amount of lead, zinc, and iron resources being wasted in copper slag.

[0004] In view of the increasing external dependence and prices of metals such as copper, lead and zinc, every additional ton of copper, lead and zinc recovered from smelting slag is of great significance to alleviating the shortage of copper, lead and zinc resources in my country and reducing the low-value utilization and waste of high-priced metals.

[0005] Among the commonly used technologies, the industry mainly uses mineral processing to recover valuable metals from copper smelting slag.

[0006] For example, in the publication number CN 105039728 A, solid copper slag, reducing agent and additive are first mixed and pelletized by the agglomeration method, and then reduced at high temperature to obtain iron-copper alloy particles and flue gas containing lead and zinc; the alloy particles are then crushed and magnetically separated to obtain iron-copper alloy particles and tailings, respectively. However, the method treats cold copper slag. Combined with the current status of the hot continuous production process of copper slag, it can no longer meet the requirements of the development of copper slag resources in my country, and it will also waste huge latent heat of hot copper slag, and the energy consumption is high. In the publication number CN117299347A, crushing and grinding are adopted, and a screening process is added during grinding. The characteristic of natural copper that it is easy to be shaped during the grinding process is utilized, and the shaped large particles of natural copper are preferentially screened and recovered, and then a high pulp concentration rapid flotation is performed to recover the copper sulfide with a faster flotation speed and the natural copper of normal size, and then the remaining copper oxide minerals are sulfided and recovered using a sulfidizing agent. However, its grinding-screening-sulfidation-regrinding-flotation process is complicated, with high cost and energy consumption. The applicant's previous patent with authorization number CN 114959279 B discloses a copper-cobalt slag reduction matte impoverishment method using gypsum solid waste and coke as solvents, which uses waste SO2 flue gas and CaSO4 components in gypsum to sulfide the oxidized metals to be recovered in the copper slag under a reducing atmosphere to make mattes for recovery; however, the SO2 and CaSO4 components added in this method cannot sulfide the copper slag to form self-powdering impoverished slag. After the slag is cooled, it is still necessary to use a cumbersome, multi-stage grinding process to crush the copper slag to meet the copper slag particle size requirements for subsequent recovery. Therefore, this method has at least the following defects: long process, high grinding energy consumption, and high requirements for SO2 flue gas recovery and treatment.

[0007] In view of this, it is urgent to optimize the technology for recovering valuable metals in copper slag, reduce the high energy consumption (accounting for more than half of the current copper slag resource cost in my country) grinding process, and solve the problems of long process, high energy consumption, and heavy environmental pollution load in the above-mentioned non-ferrous smelting slag recovery process, thereby significantly reducing costs and improving the economic benefits and environmental protection of the process. Summary of the invention

[0008] The main purpose of the present invention is to provide a method for recovering valuable metals in copper slag and its application, so as to solve the technical problems of environmental pollution of copper slag and high recycling cost.

[0009] To achieve the above object, the present invention provides a method for recovering valuable metals in copper slag, wherein a composite depleting agent is added to hot copper slag at 1180-1320° C., the hot copper slag is slowly cooled to room temperature, and is allowed to stand for more than 35 hours, and the pulverized copper slag is obtained without conventional copper slag grinding;

[0010] The particle size of the self-pulverizing copper slag is 1 mm-10 mm, and the particle size of the metal sulfide in the self-pulverizing copper slag is greater than 40 microns; the self-pulverizing copper slag is further separated and recovered by flotation after being treated, and metal sulfide, alloy and / or zinc ferrite;

[0011] The composite depleting agent comprises sodium sulfate and a carbonaceous reducing agent, and the mass ratio of sodium sulfate to the carbonaceous reducing agent in the composite depleting agent is 2-6:1;

[0012] The sulfur content in the composite depleting agent is 6 to 10 times the theoretical sulfur content required to completely sulfidize all the metal oxides in the copper slag.

[0013] Furthermore, in the step of slowly cooling the hot copper slag to room temperature, the slow cooling rate of the hot copper slag is 1-10°C / min.

[0014] Furthermore, the source of the carbonaceous reducing agent includes one or more of coke, pulverized coal, and waste carbon materials, and the source of the sodium sulfate includes waste sodium sulfate salt and / or Glauber's salt.

[0015] Furthermore, the molar ratio of fixed carbon to sodium sulfate in the composite depleting agent is 3.5-4.5:1.

[0016] Furthermore, the preparation of the composite depleting agent comprises the steps of: mixing the sodium sulfate and the carbonaceous reducing agent, granulating or pelletizing, and controlling the size of the composite depleting agent to be 0.2-5 cm.

[0017] Furthermore, the copper slag material in the hot copper slag includes one or more of copper smelting slag, copper converting slag, refining slag, depleted slag, copper sulfide ore smelting slag, matte converting slag, laterite ore reduction smelting slag and copper oxide ore reduction smelting slag; the copper smelting slag has a copper grade of 0-10% and an iron grade of 0-50%.

[0018] Furthermore, in terms of mass fraction, the chemical composition (wt%) of the copper slag includes: Fe 20-50, Cu 0.2-6.0, Pb 0.2-3.0, and Zn 0.5-5.0.

[0019] Furthermore, in the step of flotation of the self-pulverized copper slag to further separate and recover metal sulfides, alloys and / or zinc ferrite, the self-pulverized copper slag is first ball-milled before flotation, and the particle size of the self-pulverized copper slag is ball-milled to -80 to -200 mesh.

[0020] The present invention also provides an application of any of the above recovery methods in the recovery of valuable metals in copper slag obtained from pyrometallurgical copper smelting.

[0021] The beneficial effects of the present invention are as follows:

[0022] In the above-mentioned method for recovering valuable metals in copper slag and its application, and composite depleting agent, the present invention provides a composite depleting agent and a method for self-pulverizing copper slag caused by the composite depleting agent, wherein a carbonaceous reducing agent is composited with sodium sulfate, and after a series of reduction-sulfurization reactions, on the one hand, copper, lead, and zinc in the copper slag are enriched in the form of metal sulfides and alloys, and iron is mainly enriched in the form of zinc ferrite; on the other hand, the generated sodium sulfide absorbs water and expands in volume during the slow cooling process, and cooperates with the combined effect of the phase of the silicate component in the copper slag and the lattice expansion during the crystal transformation process, so as to promote the collapse of the stable structure inside the copper slag, realize the self-pulverization of the copper slag to form 1mm-10mm powder, and then change the traditional multi-stage grinding process of coarse crushing-fine crushing-ball milling of slow-cooled copper slag to one-step ball milling, thereby realizing efficient enrichment and recovery of valuable metals, shortening the copper slag resource process flow and grinding equipment investment, and greatly reducing the copper slag resource cost.

[0023] Among them, the specific reduction-sulfurization reaction in the copper slag is as follows:

[0024] The oxidized valuable metals (MeO) in the copper smelting slag undergo a series of reduction-sulfidation reactions with Na2SO4 in sodium sulfate to generate valuable metal sulfides [MeS]:

[0025] Na2SO4+4C=Na2S+4CO(g)

[0026] 2(MeO)+Na2S=2[MeS]+Na2O

[0027] As the reaction temperature of the material continues to increase, sulfate [MeSO4] will continue to decompose in a reducing atmosphere to generate the corresponding metal sulfide [MeS]:

[0028] [MeSO4]+4C=[MeS]+CO(g)

[0029] [MeSO4]+4CO(g)=[MeS]+4CO2(g)

[0030] Iron oxides and silicates in copper smelting slag will also be reduced and sulfided to [FeS], and further sulfided metal oxides in the slag:

[0031] (MeO)+[FeS]=[MeS]+(FeO)

[0032] On the other hand, the appropriate amount of sodium sulfide absorbs water and expands in volume during the slow cooling process, which promotes the pulverization of copper slag, and cooperates with the lattice expansion of the silicate component phase and crystal transformation process in the copper slag, further causing the collapse and pulverization of the stable structure inside the copper slag. Based on the above effects, the overall density of the copper slag is significantly reduced, and the particle size of the copper slag is controlled within 1mm-10mm, thereby changing the traditional multi-stage grinding process of slow cooling copper slag coarse crushing-fine crushing-re-ball milling to a one-step ball milling, effectively shortening the process flow and significantly reducing the grinding investment and operating costs.

[0033] In comparison, the copper slag treatment in commonly used technologies often requires mechanical processing such as crushing and grinding (grinding includes coarse crushing, fine crushing and ball milling) to reach the flotation threshold. The steps are complicated, energy consumption is high and the cost is high.

[0034] In addition, while ensuring the recovery rate of valuable metals, the present invention does not generate secondary waste residues, waste water and waste gas during the entire recovery process, is environmentally friendly, and has excellent application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0036] Figure 1 is a SEM image of the self-pulverizing copper slag prepared in Example 1 of the present invention;

[0037] Figure 2 is a SEM image of the self-pulverizing copper slag prepared in Example 2 of the present invention;

[0038] Figure 3 is a SEM image of the self-pulverizing copper slag prepared in Example 3 of the present invention;

[0039] Figure 4 This is a physical picture of the self-pulverizing copper slag obtained in Example 1 of the present invention;

[0040] Figure 5 It is a SEM picture of the self-pulverizing copper slag prepared in Comparative Example 1 of the present invention.

[0041] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0044] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0045] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0046] The present invention provides a method for recovering valuable metals in copper slag, comprising the steps of:

[0047] S1. Adding a composite impoverishing agent into hot copper slag, the hot copper slag is slowly cooled to room temperature and then left to stand for more than 35 hours to obtain pulverized copper slag.

[0048] The copper slag material in the hot copper slag includes one or more of copper smelting slag, copper converting slag, refining slag, depleted slag, copper sulfide ore smelting slag, matte converting slag, laterite ore reduction smelting slag and copper oxide ore reduction smelting slag; the copper smelting slag has a copper grade of 0-10% and an iron grade of 0-50%.

[0049] In some embodiments, the chemical composition of the copper slag, measured by mass fraction (wt %), includes: Fe 20-50, Cu 0.2-6.0, Pb 0.2-3.0, Zn 0.5-5.0.

[0050] For example, the hot copper slag is in a molten state and can be connected to the pyrometallurgical copper smelting process. The hot copper slag at 1180-1320°C after pyrometallurgical copper smelting can be directly recycled and processed to achieve integrated processing of copper-containing ore and copper slag.

[0051] As another example, the copper slag can also be recovered and returned to the furnace for reheating to 1200-1300° C. until the copper slag is molten to obtain hot slag.

[0052] The composite depleting agent comprises sodium sulfate and a carbonaceous reducing agent, wherein the molar ratio of fixed carbon to sodium sulfate in the composite depleting agent is 3.5-4.5:1; wherein the source of the carbonaceous reducing agent comprises one or more of coke, pulverized coal, and waste carbon materials, and the source of sodium sulfate comprises sodium sulfate waste salt and / or mirabilite. The coordinated treatment of solid wastes such as waste carbon materials and sodium sulfate waste salt with copper slag can effectively achieve the reduction and resource utilization of the above solid wastes, while reducing costs.

[0053] Exemplarily, the mass ratio of sodium sulfate waste salt to carbonaceous reducing agent can be 2-6:1.

[0054] In some embodiments, the composite depleting agent can be prepared by mixing sodium sulfate waste salt and a carbonaceous reducing agent in a mass ratio of 3 to 5:1, and then performing tableting or granulation to obtain a composite depleting agent; wherein the size of the composite depleting agent can be 0.2 to 5 cm, and the composite depleting agent of this size can be in full contact with the hot copper slag, thereby accelerating mass transfer and fully reacting.

[0055] For example, the main component of sodium sulfate waste salt is Na2SO4.

[0056] Also illustratively, the carbonaceous reducing agent includes one or more of coke, waste carbon material and pulverized coal.

[0057] In terms of mass fraction, the chemical composition of the carbonaceous reducing agent may be (wt%): C 92.00, H 3.11, S 1.85, N 1.32.

[0058] In some embodiments, the composite depleting agent can be added to the hot copper slag through the top or side feeding port of the chute. By improving the flow dynamics characteristics of the melt in the chute, the composite depleting agent can be immersed in the hot slag. As the slag flows, the composite depleting agent is evenly distributed at various positions of the melt in the slag bag, ensuring sufficient contact between the composite depleting agent and the melt.

[0059] The sulfur content in the composite depleting agent is 6 to 10 times the theoretical sulfur content required to completely sulfidize all the metal oxides in the copper slag, so as to ensure that all the metal oxides in the copper slag are sulfided-reduced.

[0060] Among them, the specific reduction-sulfurization reaction involved is as follows:

[0061] The oxidized valuable metals (MeO) in the copper smelting slag undergo a series of reduction-sulfidation reactions with Na2SO4 in sodium sulfate to generate valuable metal sulfides [MeS]:

[0062] Na2SO4+4C=Na2S+4CO(g)

[0063] 2(MeO)+Na2S=2[MeS]+Na2O

[0064] As the reaction temperature of the material continues to increase, sulfate [MeSO4] will continue to decompose in a reducing atmosphere to generate the corresponding metal sulfide [MeS]:

[0065] [MeSO4]+4C=[MeS]+CO(g)

[0066] [MeSO4]+4CO(g)=[MeS]+4CO2(g)

[0067] Iron oxides and silicates in copper smelting slag will also be reduced and sulfided to [FeS], and further sulfided metal oxides in the slag:

[0068] (MeO)+[FeS]=[MeS]+(FeO)

[0069] NaSO4 reacts with C first to obtain Na2S, and sodium sulfide undergoes an inter-sulfurization reaction with the metal oxide in the slag; at the same time, some oxides will also directly undergo a reduction reaction with carbon to obtain metals or alloys. The temperature also drops to a certain temperature, and the easily sulfided and easily reduced oxides are reduced to a certain limit, and zinc oxide and iron oxide eutectic precipitate zinc ferrite, ultimately achieving copper and lead enrichment in the form of metal matte and alloy, and zinc and iron are mainly enriched in the form of zinc ferrite.

[0070] It should also be noted that, under the slightly reducing atmosphere in step S1, the copper, lead and zinc components in the copper slag are synergistically sulfided and converted into metal matte particles, and the matte particles continue to aggregate and grow during the slow cooling process, reaching the particle size requirement (>40μm) that is beneficial to the subsequent flotation. In addition, an appropriate amount of sodium sulfide promotes the pulverization of the copper slag due to its volume expansion due to water absorption during the slow cooling process, and synergizes with the lattice expansion of the phase and crystal form transformation process of the silicate component in the copper slag, further causing the internal stable structure of the copper slag to collapse and pulverize. The particle size of the copper slag after pulverization is 1mm-10mm.

[0071] For example, after the copper slag is slowly cooled to room temperature, it can be left to stand in a humid environment. A higher water content in the air is beneficial to improving the pulverization efficiency of the copper slag.

[0072] In some embodiments, the slow cooling rate of the hot copper slag can be controlled at 1-10° C. / min.

[0073] S2. The self-pulverized copper slag is further separated and recovered by flotation to obtain metal sulfides, alloys and / or zinc ferrite;

[0074] Among them, flotation, as a commonly used mineral processing method, has the advantages of low cost, strong applicability, easy process control, and environmental friendliness compared to hydrometallurgy and pyrometallurgy, and therefore has received more widespread attention. Flotation has been proven to achieve excellent flotation indicators when treating most copper slags and has been applied on a large scale in industry. However, there are certain limitations on the sulfide particle size (required to be above 40 microns) and the ore size (required to be 0.01mm-0.25mm). When the metal sulfide grows insufficiently, it is mainly distributed in fine particles and has a complex relationship with the gangue minerals, resulting in poor separation effect. When the ore size is too large, grinding treatment is required to meet the flotation requirements, otherwise the ore particles are easy to settle in the flotation process and enrich in the flotation tailings, affecting the recovery rate of each metal sulfide and zinc ferrite.

[0075] In the present application, under the slightly reducing atmosphere in step S1, the copper, lead and zinc components in the copper slag are synergistically sulfided and converted into metal matte particles. The matte particles continue to aggregate and grow during the slow cooling process, reaching the particle size requirement (>40μm) that is beneficial to the subsequent flotation. In addition, an appropriate amount of sodium sulfide promotes the pulverization of the copper slag due to its volume expansion due to water absorption during the slow cooling process, and synergizes with the lattice expansion of the silicate component in the copper slag during the phase and crystal transformation process, further promoting the collapse and pulverization of the stable structure inside the copper slag, and the particle size of the self-pulverized copper slag is controlled at 1~10mm.

[0076] Based on the above effects, the overall density of copper slag is significantly reduced, thereby changing the traditional slow-cooling copper slag coarse crushing-fine crushing-ball milling grinding process to one-step ball milling, effectively shortening the process flow and significantly reducing grinding investment and operating costs.

[0077] For example, the self-pulverized copper slag can be ball-milled to -80 to -200 mesh and then subjected to flotation treatment.

[0078] It is also necessary to explain that grinding is a permanent process of flotation, which can crush the ore particles in the copper slag to an appropriate particle size, so that the useful minerals and the gangue minerals are fully dissociated, which is beneficial to the subsequent flotation operation. The copper slag particles after grinding are finer and the surface area is increased, which is more conducive to the adsorption of flotation reagents and the carrying of foam, thereby improving the flotation recovery rate and concentrate grade.

[0079] Since the copper slag of the present invention is pulverized under the synergistic influence of excess sodium sulfide and silicate lattice expansion, simple ball milling can also achieve excellent indicators in flotation. In this way, on the one hand, the cost is effectively reduced and the energy consumption is greatly reduced:

[0080] The coarse and fine crushing in grinding are the parts with higher costs in the mineral processing, including power consumption, metal material consumption and equipment investment. Simplifying the grinding steps can significantly reduce the mineral processing costs. The grinding process requires a lot of electricity and mechanical energy. Reducing grinding can significantly reduce energy consumption, which meets the current environmental protection requirements of energy conservation and emission reduction.

[0081] On the other hand, production efficiency has been significantly improved:

[0082] The grinding process takes a long time, and reducing grinding can shorten the time of the entire beneficiation process and improve production efficiency. At the same time, equipment failure or maintenance requirements may occur during the grinding process, and reducing grinding can reduce these potential production interruptions.

[0083] In some embodiments, flotation may include the steps of adding a flotation agent to sink the matte particles to the bottom, thereby separating the matte from the slag, and separating and recovering the metal sulfide and the floating zinc ferrite.

[0084] Metal sulfides are separated from the silicate copper slag after slow cooling to form a single metal matte ore phase, and then valuable metals such as lead, zinc and copper are recovered through the flotation process. The recovered metal matte / alloy (sulfides and alloys such as copper, lead, zinc and iron) are sent to the next step of blowing for further recovery, and the flotation tailings of the copper slag are then washed again to recover zinc ferrite and magnetite.

[0085] The present invention can not only synergistically utilize hazardous wastes such as waste carbon materials and sodium sulfate waste salt to efficiently recover valuable metals in copper slag, but also the heavy metal elements in the above hazardous wastes are transformed into the silicate lattice in the self-pulverized copper slag during the slow cooling process to be stabilized.

[0086] Since pulverized copper slag is a general solid waste, it can be sold as raw materials for cement and building materials after recovering elements such as lead, zinc, copper and iron, which meets the requirements of green and clean development of the metallurgical industry.

[0087] The present invention also provides an application of any of the above recovery methods in the recovery of valuable metals in copper slag obtained from pyrometallurgical copper smelting.

[0088] Example 1

[0089] Take 100g of domestic flash smelting slag, whose chemical composition by mass fraction includes Cu 1.68%, Pb1.5%, Fe 39.34%, O 0.27%, S 0.68%, Zn 3.44%, CaO 6.35%, SiO229.28%, add 47g of composite impoverishing agent at 1250℃, whose composition is 12g of coke powder and 35g of mirabilite (sodium sulfate). Keep the cooling rate at 1℃ / min to obtain slow-cooling copper slag. Figure 1 The SEM image of the slow-cooled copper slag obtained. After separation and sampling, the enrichment rates of copper and lead in the copper matte are 91.69% and 92.17%, respectively. The slow-cooled copper slag is left to stand for 38 hours in a humid environment to obtain the self-pulverized copper slag. The particle size of the self-pulverized copper slag is 1-10 mm. The particle size of the metal sulfide in the self-pulverized copper slag is greater than 40 microns. The main component of the matte phase of the self-pulverized copper slag is Cu 39 S 28, FeS, Fe3S4, ZnS and other sulfides.

[0090] After the pulverized copper slag is ball-milled to -80 to -200 mesh, the above metal sulfides can be effectively recovered in the subsequent flotation stage.

[0091] Example 2

[0092] Take 100g of Shandong copper smelting slag with chemical composition (wt%) including: Fe 40.13, Cu 3.25, Pb 1.03, Zn3.65, Ca 2.61, Si 11.59, add 47g of composite impoverishing agent at 1300℃, which consists of 12g of coke powder and 35g of sodium sulfate, and keep the cooling rate at 1℃ / min to obtain slow-cooling copper slag. Figure 2 The SEM image of the slow-cooled copper slag obtained. After separation and sampling, the enrichment rates of copper and lead in the copper matte are 92.3% and 93.5%, respectively. The slow-cooled copper slag is left to stand in a humid environment for 38 hours to obtain the self-pulverized copper slag. The particle size of the self-pulverized copper slag is 1-10 mm. The particle size of the metal sulfide in the self-pulverized copper slag is greater than 40 microns. The main component of the matte phase of the self-pulverized copper slag is Cu 39 S 28 , FeS, Fe3S4, ZnS and other sulfides.

[0093] After the pulverized copper slag is ball-milled to -80 to -200 mesh, the above metal sulfides can be effectively recovered in the subsequent flotation stage.

[0094] Example 3

[0095] Take 100g of Shandong copper smelting slag with a chemical composition (wt%) including: Fe 40.13, Cu 3.25, Pb 1.03, Zn3.65, Ca 2.61, Si 11.59. At 1300℃, add 53.7g of composite depletion agent, which consists of 13.7g of coke powder and 40g of sodium sulfate. Keep the cooling rate at 1℃ / min to obtain slowly cooled copper slag. Figure 3 The SEM image of the slow-cooled copper slag obtained. After separation and sampling, the enrichment rates of copper and lead in the copper matte are 91.3% and 92.5%, respectively. The slow-cooled copper slag is left to stand for 38 hours in a humid environment to obtain the self-pulverized copper slag. The particle size of the self-pulverized copper slag is 1-10 mm. The particle size of the metal sulfide in the self-pulverized copper slag is greater than 40 microns. The main component of the matte phase of the self-pulverized copper slag is Cu 39 S 28 , FeS, Fe3S4, ZnS and other sulfides.

[0096] After the pulverized copper slag is ball-milled to -80 to -200 mesh, the above metal sulfides can be effectively recovered in the subsequent flotation stage.

[0097] Comparative Example 1

[0098] The slag of a domestic flash smelting smelting contains Cu 1.68%, Fe 39.34%, O 0.27%, S 0.68%, Zn3.44%, CaO 6.35%, SiO229.28%. A composite impoverishing agent composed of 12% coke powder and 12% sodium sulfate (sodium sulfate) was added at 1250℃, and the cooling rate was maintained at 2℃ / min to obtain a slowly cooled copper slag. Figure 5 The SEM image of the slowly cooled copper slag is shown in Figure 2. Figure 5 It can be seen that the copper, lead and zinc enrichment effect is poor, and most of them are tiny matte particles, which cannot meet the flotation requirements; the slowly cooled copper slag was left to stand in a humid environment for 38 hours, and no powdering phenomenon occurred.

[0099] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the protection scope of the present invention.

Claims

1. A method for recovering valuable metals in copper slag, characterized in that: The composite impoverishing agent is added to the hot copper slag at 1180-1320° C., the hot copper slag is slowly cooled to room temperature, and is allowed to stand for more than 35 hours in a humid environment, and the pulverized copper slag is obtained without conventional copper slag grinding; The particle size of the self-pulverizing copper slag is 1 mm-10 mm, and the particle size of the metal sulfide in the self-pulverizing copper slag is greater than 40 microns; the self-pulverizing copper slag is further separated and recovered by flotation after being treated, and metal sulfide, alloy and / or zinc ferrite; The composite depleting agent comprises sodium sulfate and a carbonaceous reducing agent, and the mass ratio of sodium sulfate to the carbonaceous reducing agent in the composite depleting agent is 2-6:1; The sulfur content in the composite depleting agent is 6 to 10 times the theoretical sulfur content required to completely sulfidize all the metal oxides in the copper slag.

2. The method for recovering valuable metals in copper slag according to claim 1, characterized in that: In the step of slowly cooling the hot copper slag to room temperature, the slow cooling rate of the hot copper slag is 1-10° C. / min.

3. The method for recovering valuable metals in copper slag according to claim 1, characterized in that: The source of the carbonaceous reducing agent includes one or more of coke, pulverized coal, and waste carbon materials, and the source of the sodium sulfate includes waste sodium sulfate salt and / or sodium sulfate.

4. The method for recovering valuable metals in copper slag according to claim 1, characterized in that: The molar ratio of fixed carbon to sodium sulfate in the composite depleting agent is 3.5-4.5:

1.

5. The method for recovering valuable metals in copper slag according to claim 1, characterized in that: The preparation of the composite depleting agent comprises the following steps: mixing the sodium sulfate and the carbonaceous reducing agent, granulating or pelletizing, and tableting, and controlling the size of the composite depleting agent to be 0.2-5 cm.

6. The method for recovering valuable metals in copper slag according to claim 1, characterized in that: The copper slag material in the hot copper slag includes one or more of copper smelting slag, copper converting slag, refining slag, depleted slag, copper sulfide ore smelting slag, matte converting slag, laterite ore reduction smelting slag and copper oxide ore reduction smelting slag; the copper grade in the copper slag is 0-10%, and the iron grade is 0-50%.

7. The method for recovering valuable metals in copper slag according to claim 6, characterized in that: Calculated by mass fraction, the chemical composition of the copper slag includes: Fe 20-50, Cu 0.2-6.0, Pb 0.2-3.0, and Zn 0.5-5.

0.

8. The method for recovering valuable metals in copper slag according to claim 1, characterized in that: In the step of further separating and recovering metal sulfides, alloys and / or zinc ferrite by flotation after the self-pulverizing copper slag is treated, the self-pulverizing copper slag is first subjected to simple ball milling treatment before flotation, and the particle size of the self-pulverizing copper slag is ball milled to -80 to -200 mesh.

9. Use of the recovery method as claimed in any one of claims 1 to 8 in the recovery of valuable metals in copper slag obtained from pyrometallurgical copper smelting.

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