Method and device for recovering valuable metals from copper smelting slag

Abstract

The invention provides a method and a device for recovering valuable metals from copper smelting slag, and the method for recovering valuable metals from copper smelting slag comprises the following steps: before molten copper smelting slag is transferred into a slag ladle for cooling, adding first gas, gypsum slag and nitrogen into the molten copper smelting slag in a plasma injection mode, and after injection is completed, adding second gas into the slag ladle for cooling; and metal gaseous substances and copper slag are obtained. Carrying out post-treatment and flotation on the copper slag to obtain a valuable metal sulfonium phase and depleted slag; wherein the first gas is one or more of CO, H2, CO2 and CH4; and the metal gaseous substances comprise gaseous lead and gaseous zinc. And the valuable metal sulfonium phase is sulfides of copper, iron, lead and zinc. The process method and device are simple, the production time is shortened, CO2 emission can be reduced, secondary pollution caused by waste water and waste residues is avoided, and the green metallurgy requirement is met.

Description

Technical Field

[0001] The present invention belongs to the field of valuable metal recovery, and in particular relates to a method and device for recovering valuable metals from copper smelting slag. Background Art

[0002] Copper slag is a byproduct of the pyrometallurgical copper smelting process, with approximately 2-3 tons of slag emitted for every ton of refined copper produced. The storage of large quantities of copper slag requires land or farmland, and its complex composition causes varying degrees of environmental pollution. However, copper slag contains a wealth of potentially usable resources. Currently, copper slag is primarily used for beneficiation to recover valuable metals and tailings for cement and building materials. Traditional flotation processes can only significantly recover mechanically entrained copper sulfide particles, but are unable to simultaneously recover oxidized copper. In existing copper mineral resources, heavy metals such as lead, zinc, and iron often coexist with copper. During the copper smelting process, these elements are considered impurities and are typically removed from the smelting slag. However, current copper slag recovery processes do not adequately address the recovery of lead, zinc, and iron, resulting in the waste of these valuable metal resources. With copper prices continuing to rise, recovering more copper from smelting slag is crucial for alleviating my country's copper resource shortage and reducing the underutilization and waste of high-value metals.

[0003] In the prior art, although traditional hydrometallurgy can effectively recover iron elements, it produces a large amount of leachate and acidic waste slag, which are difficult to treat and cause secondary pollution. Usually, only a single valuable metal can be recovered from copper slag, and lead, zinc, and iron cannot be recovered simultaneously. The pyrometallurgical process achieves metal recovery through high-temperature reduction and flue gas treatment. Although it can simultaneously process multiple metals in copper slag, the main focus is on the recovery of iron and zinc, the energy consumption is high, and the process flow is complicated. Based on this, the present application proposes a method and device for recovering valuable metals from copper smelting slag. Summary of the Invention

[0004] The main purpose of the present invention is to provide a method and device for recovering valuable metals from copper smelting slag, aiming to solve the technical problems existing in the prior art of single type of valuable metal recovery, low recovery efficiency and secondary pollution.

[0005] To achieve the above objectives, the present invention provides a method for recovering valuable metals from copper smelting slag, comprising: before the molten copper smelting slag is transferred to a slag ladle for cooling, adding a first gas, gypsum slag and nitrogen to the molten copper smelting slag by plasma injection, after which metal gas and copper slag are obtained; and then post-processing the copper slag to obtain a valuable metal matte phase and depleted slag.

[0006] Wherein, the first gas is one or more of CO, H2, CO2, and CH4.

[0007] The metal gas includes gaseous lead and gaseous zinc.

[0008] The valuable metal matte phase is sulfides of copper, iron, lead and zinc.

[0009] According to an embodiment of the present application, the steps of post-processing the copper slag include: cooling, grinding and flotation.

[0010] The cooling time is 20 to 30 hours, and the powder particle size of the grinding is 35 to 100 μm.

[0011] According to an embodiment of the present application, the volume ratio of the first gas to nitrogen is 1:4 to 2:3.

[0012] According to an embodiment of the present application, the amount of the first gas added is 1 to 5 times the amount of the lead-zinc compounds in the copper smelting slag that are completely reduced.

[0013] According to an embodiment of the present application, the mass of the gypsum slag is 1 to 5 times the theoretical amount of completely sulfided oxidized copper in the copper smelting slag.

[0014] According to an embodiment of the present application, the chemical composition of the copper smelting slag is, by mass fraction, 20-50% Fe, 0.2-6.0% Cu, 0.2-3.0% Pb, and 0.5-5.0% Zn.

[0015] According to an embodiment of the present application, the gypsum slag includes desulfurization gypsum in a smelter and / or neutralizing gypsum in wastewater.

[0016] Among them, the main component of desulfurization gypsum slag is CaSO4·xH2O.

[0017] According to the embodiment of the present application, the temperature of the plasma is 5000-15000K, and the power density is 5-15kW / cm 2 , the plasma flow rate is 300~500L / min.

[0018] The present application also provides a device for recovering valuable metals from copper smelting slag, comprising:

[0019] The copper smelting furnace is used to heat copper smelting slag into molten copper smelting slag.

[0020] The slag chute is connected to the discharge port of the copper smelting furnace and is used to transfer the molten copper smelting slag.

[0021] The plasma device has a spraying range covering the molten copper smelting slag in the slag chute and is used to add gypsum slag and nitrogen into the molten copper smelting slag in a plasma spraying manner.

[0022] The slag ladle is located below the slag chute and is used to receive and cool the molten copper smelting slag.

[0023] The gas recovery device is set at the position of the molten copper smelting slag in the plasma blowing slag chute to collect the metal gas generated at the moment of plasma blowing.

[0024] According to an embodiment of the present application, the plasma device includes a plurality of plasma spray guns, which are distributed in a circular array, and 1 to 3 plasma spray guns are provided at the discharge port of each cubic meter of the copper smelting furnace.

[0025] The beneficial effects of the present invention are:

[0026] The method for recovering valuable metals from copper smelting slag disclosed herein utilizes the high temperature and high energy density of plasma to inject a first gas, gypsum slag, and nitrogen into the molten copper smelting slag before it is transferred to a slag ladle for cooling. In the plasma state, the first gas significantly enhances the reducing power and reaction rate of active groups generated by the first gas, effectively reducing metal oxides in the copper smelting slag and improving the recovery rate of valuable metals. The high-temperature plasma also reduces the viscosity of the copper smelting slag, thereby increasing its fluidity and promoting the sedimentation of the metal matte phase, which is beneficial for improving subsequent flotation efficiency. The fluidity of the molten copper smelting slag during the transfer process is coordinated to achieve uniform stirring, promote sufficient reaction, and produce metal gaseous products and copper slag, wherein the metal gaseous products include gaseous lead and gaseous zinc. Post-treatment of the copper slag promotes the growth of copper sulfide and metallic copper crystal particles, improving the subsequent copper flotation recovery rate, producing a valuable metal matte phase and depleted slag, and achieving the recovery of multiple metals from the copper smelting slag. Moreover, the process method of the present application is simple, easy to operate, reduces production time, can also reduce CO2 emissions, and has no secondary pollution from wastewater and waste residue, thus meeting the requirements of green metallurgy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0028] Figure 1 is the XRD pattern of the cooled slag prepared in Example 1 of the present invention;

[0029] Figure 2 This is a physical picture of the cooled slag prepared in Example 1 of the present invention;

[0030] Figure 3 This is a SEM image of the cooled slag prepared in Example 1 of the present invention;

[0031] Figure 4 This is a physical picture of the cooled slag prepared in Example 2 of the present invention;

[0032] Figure 5 : is the XRD pattern of the cooled slag prepared in Example 2 of the present invention;

[0033] Figure 6 This is a SEM image of the cooled slag prepared in Example 2 of the present invention;

[0034] Figure 7 This is a physical picture of the cooled slag sample prepared in Comparative Example 1 of the present invention;

[0035] Figure 8 This is an SEM image of the cooled slag sample prepared in Comparative Example 1 of the present invention.

[0036] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0037] The following will be combined with the accompanying 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 embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0038] Moreover, 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 ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] To achieve the above objectives, the present invention provides a method for recovering valuable metals from copper smelting slag, comprising: before the molten copper smelting slag is transferred to a slag ladle for cooling, adding a first gas, gypsum slag and nitrogen to the molten copper smelting slag by plasma injection, thereby obtaining metal gas and copper slag after the injection; and then post-treating the copper smelting slag to obtain a valuable metal matte phase and depleted slag.

[0040] Wherein, the first gas is one or more of CO, H2, CO2, and CH4.

[0041] The metal gas includes gaseous lead and gaseous zinc.

[0042] The valuable metal matte phase is sulfides of copper, iron, lead and zinc.

[0043] In some embodiments, copper smelting slag is heated to a molten state in a copper smelting furnace. Before the molten copper smelting slag is transferred to a slag ladle for natural cooling, a plasma injection method is used to inject a first gas, gypsum slag, and nitrogen onto the surface or interior of the molten copper smelting slag. The flow of the copper smelting slag allows for thorough mixing of the generated plasma, promoting chemical reactions. For example, lead and zinc oxides in the copper smelting slag are reduced to gaseous lead and gaseous zinc, which are then recovered in gaseous form. High-temperature plasma can also reduce the viscosity of the copper smelting slag, such as by converting Fe3O4 to FeO, which reduces viscosity and improves fluidity, thereby facilitating subsequent flotation efficiency.

[0044] At the same time, after the injection is completed, the molten copper smelting slag is passed into the slag bag for natural cooling (therefore, the cooling time is relatively long, such as 20 to 30 hours), so that the molten copper smelting slag in the slag bag is slowly cooled, which is conducive to the growth of copper sulfide and metallic copper crystal particles, and improves the subsequent flotation copper recovery rate. In addition, natural cooling can reduce the slag temperature in the slag bag to a certain range, so that the hardness of the slag is relatively reduced. This is conducive to subsequent grinding and thus reduces energy consumption. Subsequent grinding is carried out to obtain a powder particle size of 35μm to 100μm, which is then subjected to flotation separation to achieve the recovery of multiple metals in the copper smelting slag.

[0045] Among them, the specific sulfidation-reduction reaction occurring in the present invention includes:

[0046] The oxidized valuable metals (MeO) in the copper smelting slag and the CaSO4 in the gypsum solid waste undergo a series of reactions through CO plasma-enhanced reduction to produce valuable metal sulfides [MeS] and pure metals:

[0047] CuO+[S 2- ]=CuS+O 2-

[0048] Under a strong reducing atmosphere, lead-zinc oxide (MeO) and lead-zinc silicate in the smelting slag will also be reduced to metal elements and enter the gas phase:

[0049] MeO + reducing atmosphere = [Me] (g)

[0050] Me x SiOy + reducing atmosphere = Me(g)

[0051] The above-mentioned method for recovering valuable metals from copper smelting slag involves injecting a first gas, gypsum slag, and nitrogen onto the surface of or within the molten copper smelting slag before the molten copper smelting slag is transferred to a slag ladle for cooling. Under the action of a first gas, the high temperature and high energy density of a plasma are utilized. The first gas, in a plasma state, significantly enhances the reducing power and reaction rate of active groups generated by the first gas, effectively reducing metal oxides in the copper smelting slag and improving the recovery rate of valuable metals. The high-temperature plasma also reduces the viscosity of the copper smelting slag, thereby increasing its fluidity and promoting the sedimentation of the metal matte phase, which is beneficial for improving subsequent flotation efficiency. The fluidity of the molten copper smelting slag during the transfer process is coordinated to achieve uniform stirring, promote sufficient reaction, and produce metal gaseous products and copper slag. Post-treatment of the copper slag promotes the growth of copper sulfide and metallic copper crystal particles, improving the subsequent copper flotation recovery rate, producing a valuable metal matte phase and depleted slag, and achieving the recovery of multiple metals from the copper smelting slag.

[0052] The process method of the application is simple, easy to operate, reduces production time, can also reduce CO2 emissions, and has no secondary pollution from wastewater and waste residue, and meets the requirements of green metallurgy.

[0053] In some embodiments, the volume ratio of the first gas to nitrogen is 1:4 to 2:3.

[0054] N2 plasma can be generated through methods such as arc discharge. N2 can generate high-temperature plasma when excited by a plasma gun. To maintain the plasma state, a certain concentration of N2 gas is required. Therefore, by controlling the ratio of the first gas to nitrogen, the concentration of the effective reactants in the reaction system can be adjusted. For example, when the CO content in the first gas is high, the reaction rate will accelerate. In this case, appropriately increasing the proportion of nitrogen can slow the reaction rate and make the reaction more stable.

[0055] In some embodiments, in a plasma environment, CO2 molecules are excited or ionized by high-energy electrons to generate active radicals, such as CO2 + 、CO + , O + CH4 molecules will be excited or ionized by high-energy electrons to generate active groups, such as CH3 + 、CH2 + 、CH + 、C + and H + The high temperature and high energy density of plasma can further enhance the reduction ability and reaction rate of CO2 and CH4, effectively reduce metal oxides, and improve the recovery rate of metals.

[0056] In some embodiments, the amount of the first gas added is 1 to 5 times the amount required to completely reduce the lead and zinc compounds in the copper smelting slag.

[0057] Copper smelting slag usually contains lead (Pb) and zinc (Zn) oxides or sulfides. By adjusting the amount of lead (Pb) and zinc (Zn) added to 1 to 5 times the amount of the fully reduced amount, it can ensure that the lead and zinc compounds in the copper smelting slag are fully reduced, avoiding the partial unreduction of lead and zinc due to insufficient reducing agent, thereby significantly improving the recovery rate of valuable metals such as copper, lead, and zinc, reducing resource waste, and reducing the impact of harmful elements.

[0058] In some embodiments, the mass of the gypsum slag is 1 to 5 times the theoretical amount of completely sulfided oxidized copper in the copper smelting slag.

[0059] In some embodiments, the gypsum slag comprises desulfurized gypsum from a smelter and / or neutralized gypsum from wastewater, wherein the desulfurized gypsum slag is primarily composed of CaSO4·xH2O. The chemical composition of the gypsum slag, by mass, is as follows: Ca 25.0-30.0%, Mg 0.45-0.50%, K 0.03-0.035%, Fe 0.10-0.15%, Cd 0.010-0.015%, Cu 0.0003-0.0006%, S 17.00-20.00%, and Pb 0.010-0.013%.

[0060] Calcium sulfate (CaSO4) in gypsum slag can decompose to form calcium sulfide (CaS) at high temperature. Calcium sulfide, as a sulfiding agent, can react with oxidized copper to form copper sulfide, thereby converting copper from an oxidized state to a sulfided state. Controlling the amount of gypsum slag added can ensure that the oxidized copper is fully sulfided and improve the copper recovery rate. The addition of gypsum slag can change the chemical composition of copper smelting slag, reduce viscosity, and improve the separation of valuable metal matte phase and depleted slag. Because gypsum slag is a waste generated in the copper smelting process, using it to treat copper smelting slag can not only reduce waste emissions, but also achieve resource recycling. The process is simple, reduces energy consumption and costs, and is easy to implement industrial applications.

[0061] In some embodiments, the chemical composition of the copper smelting slag is, by mass fraction, 20-50% Fe, 0.2-6.0% Cu, 0.2-3.0% Pb, and 0.5-5.0% Zn.

[0062] In some embodiments, the copper smelting slag is derived from a combination of bornite, chalcocite, metallic copper, magnetite, fayalite, and amorphous materials. For example, the copper smelting slag has a copper grade of 0-10%, an iron grade of 0-50%, and a lead and zinc grade of 1-5%.

[0063] In some embodiments, the gypsum slag includes desulfurization gypsum from a smelter and / or neutralized gypsum from wastewater.

[0064] Among them, the main component of desulfurization gypsum slag is CaSO4·xH2O.

[0065] In some embodiments, the plasma temperature is 2000-3500K, and the power density is 5-15 kW / cm 2 , the plasma flow rate is 300~500L / min.

[0066] In some embodiments, the high temperature of the plasma can cause copper oxides or sulfides in the copper smelting slag to decompose into a more easily handled form, thereby improving the copper recovery rate. In a high temperature environment, the rate of chemical reaction is significantly accelerated, which helps to complete the smelting process in a shorter time and improve production efficiency. High power density helps to maintain the high temperature state of the plasma and ensure the continuous progress of the reaction. The appropriate flow rate can ensure the effective transfer of heat and reactants in the plasma, making the reaction more uniform. By adjusting the flow rate, the coverage and action area of the plasma can be controlled, improving production efficiency and product quality.

[0067] The present application also provides a device for recovering valuable metals from copper smelting slag, comprising:

[0068] Copper smelting furnace is used to heat copper smelting slag into molten copper smelting slag. For example, medium frequency furnace is used.

[0069] The slag chute is connected to the discharge port of the copper smelting furnace and is used to transfer the molten copper smelting slag.

[0070] The plasma device has a spraying range covering the molten copper smelting slag in the slag chute and is used to add gypsum slag and nitrogen into the molten copper smelting slag in a plasma spraying manner.

[0071] The slag ladle is located below the slag chute and is used to receive and cool the molten copper smelting slag.

[0072] The gas recovery device is set at the position of the molten copper smelting slag in the plasma blowing slag chute to collect the metal gas generated at the moment of plasma blowing.

[0073] In some embodiments, a gas recovery device is provided to collect metal gaseous substances generated at the moment of plasma blowing, thereby improving the recovery rate of valuable metals, reducing the emission of harmful gases and dust, stabilizing the process flow, reducing costs, and realizing the recycling of resources.

[0074] The slag chute is used to transfer molten copper smelting slag from the copper smelting furnace to the slag ladle. The slag chute is an inclined channel that uses gravity to guide the molten copper smelting slag from the copper smelting furnace outlet to the slag ladle. The slag chute must be designed to ensure smooth flow of molten slag and avoid blockage.

[0075] The plasma device injects the first gas, gypsum slag and nitrogen into the surface or inside of the molten copper smelting slag in a blowing manner, and uses the high temperature and high energy density of the plasma to excite the sulfur element in the gypsum slag into [S 2- ]. In a reducing atmosphere, it chemically reacts with molten copper smelting slag.

[0076] In some embodiments, the position of the plasma device is controlled to achieve more uniform and effective plasma jet coverage of the copper smelting slag surface, resulting in higher heating efficiency and shorter holding time. Furthermore, the plasma jet, generated by the flow and agitation of the molten copper slag during its fall, achieves the reduction and volatilization of some lead and zinc oxides and the sulfidation conversion of copper oxide, while also facilitating the thorough mixing of the added first gas, gypsum slag, and copper smelting slag.

[0077] In some embodiments, the plasma device includes a plurality of plasma spray guns, which are distributed in a circular array, and 1 to 3 plasma spray guns are provided at the discharge port of each cubic meter of the copper smelting furnace.

[0078] For further understanding of the present invention, now illustrate with examples:

[0079] Example 1

[0080] Gypsum slag was dried to a moisture content of less than 15%, then ground in a mortar until it passed a 200-mesh sieve. The chemical composition of the gypsum slag, calculated by mass percentage, was as follows: Ca 28.0%, Mg 0.49%, K 0.033%, Fe 0.11%, Cd 0.010%, Cu 0.0005%, S 19.00%, and Pb 0.011%. 100g of bottom-blown copper slag from a smelter was collected. The chemical composition, calculated by mass percentage, was as follows: Fe 40.13%, Cu 3.25%, Pb 1.03%, Zn 3.65%, Ca 2.61%, and Si 11.59%. The copper slag was rapidly melted in a medium-frequency furnace. The plasma torch was used to spray the molten copper slag in the slag chute. After successful arc ignition using N2 plasma, the CO concentration was maintained at 20%. ， The volume ratio of CO to nitrogen was 1:4, and the injection rate was 80 L / min. Simultaneously, 9.16 g of gypsum slag was injected onto the surface of or into the molten copper smelting slag for 10 minutes before the molten copper smelting slag was transferred to a slag ladle for cooling. The molten copper smelting slag was then passed into the slag ladle and cooled for 24 hours to produce cooled slag. The cooled slag contained valuable metal matte and depleted slag.

[0081] Figure 1The XRD pattern of the cooled slag prepared in Example 1 shows that the main phases in the depleted slag are Fe2SiO4, Fe3O4 and Fe2O3. The matte phase in the valuable metal matte phase is mainly composed of Cu 39 S 28 , FeS, Fe3S4 and other sulfides.

[0082] Figure 2 This is a physical picture of the cooling slag prepared in Example 1. It can be seen that the matte phase settles to the bottom layer and has a clear dividing line with the depleted slag. The above-mentioned matte phase can be effectively recovered in the subsequent mineral processing stage, and the generated lead and zinc elements are volatilized into the flue gas for condensation recovery.

[0083] Figure 3 This is a SEM image of the cooled slag produced in Example 1. The results show that the particle size of the Cu-Fe-S matte particles and Fe-S sulfides exceeds 100 μm, enabling efficient recovery in sulfide grinding and flotation. Furthermore, a clear boundary exists between the Fe-S sulfide and the Fe-O-Si-Ca depleted slag phase, facilitating the dissociation of the mineral monomers. Calculated copper sulfide enrichment exceeds 94.6%, and the lead and zinc volatilization rate exceeds 95.6%.

[0084] Example 2

[0085] Gypsum slag was dried to a moisture content of less than 15%, then ground in a mortar until it passed a 200-mesh sieve. The chemical composition of the gypsum slag, by mass percentage, was as follows: Ca 28.0%, Mg 0.49%, K 0.033%, Fe 0.11%, Cd 0.010%, Cu 0.0005%, S 19.00%, and Pb 0.011%. 100g of bottom-blown copper slag from a smelter was collected. The chemical composition, by mass percentage, was as follows: Fe 40.13%, Cu 3.25%, Pb 1.03%, Zn 3.65%, Ca 2.61%, and Si 11.59%. The copper slag was rapidly melted in an intermediate frequency furnace. The plasma torch was used to spray the molten copper slag in the slag chute. After successful arc ignition using N2 plasma, the H2 concentration was maintained at 30%. The H2:N2 gas was injected at a volume ratio of 3:10 at a flow rate of 80 L / min. Simultaneously, 9.16 g of gypsum slag was injected into the molten copper slag for 10 minutes before it was transferred to a slag ladle for cooling. The molten copper slag was then passed into the slag ladle and cooled for 24 hours to produce cooled slag. The cooled slag contained valuable metal matte and depleted slag.

[0086] Figure 4This is a photo of the cooled slag produced in Example 2. It shows obvious stratification, with the matte layer settling to the bottom and forming a distinct boundary with the depleted slag. Large copper matte particles also appear in the depleted slag. Figure 5 The XRD pattern of the cooled slag prepared in Example 2 shows that the main phases in the depleted slag are Fe2SiO4, Fe3O4 and Fe2O3. The main components of the matte phase are Cu 39 S 28 , FeS, Fe3S4 and other sulfides, which can be effectively recovered in the subsequent beneficiation stage. The generated lead and zinc elements volatilize into the flue gas.

[0087] Figure 6 This is a SEM image of the cooled slag produced in Example 2. It shows that the Cu-Fe-S matte particles and Fe-S sulfides have a particle size greater than 50 μm, allowing for efficient recovery in sulfide grinding and flotation. Furthermore, a clear boundary exists between the sulfides and the Fe-O-Si-Ca depleted slag phase, facilitating the dissociation of the mineral monomers. Calculations show that the copper enrichment rate in the sulfides exceeds 95%, and the lead and zinc volatilization rate exceeds 87.8%.

[0088] Example 3

[0089] Gypsum slag was dried to a moisture content of less than 15%, then ground in a mortar until it passed a 200-mesh sieve. The chemical composition of the gypsum slag, calculated by mass percentage, was as follows: Ca 28.0%, Mg 0.49%, K 0.033%, Fe 0.11%, Cd 0.010%, Cu 0.0005%, S 19.00%, and Pb 0.011%. A sample of 100 g of bottom-blown copper slag from a smelter revealed the following chemical composition, calculated by mass percentage,: Fe 40.13%, Cu 3.25%, Pb 1.03%, Zn 3.65%, Ca 2.61%, and Si 11.59%. The copper smelting slag is placed in a medium frequency furnace for rapid melting. The plasma spray gun covers the molten copper smelting slag in the slag chute. After the N2 plasma arc is successfully struck, the volume concentration of the mixture of CO2 and CH4 is maintained at 30%, and the spraying flow rate is 80L / min. At the same time, before the molten copper smelting slag is transferred to the slag bag for cooling, 9.16g of gypsum slag is sprayed into the molten copper slag for 10 minutes. After the spraying is completed, the molten copper smelting slag is passed into the slag bag and cooled in the slag bag for 24 hours to obtain cooled slag. The cooled slag includes valuable metal matte phase and depleted slag.

[0090] The cooled slag exhibits distinct stratification, with the matte layer settling to the bottom and forming a distinct boundary with the depleted slag. Large copper matte particles also appear in the depleted slag. These can be effectively recovered in the subsequent beneficiation stage. The resulting elemental lead and zinc volatilize into the flue gas. Calculations indicate that the copper enrichment rate in the sulfides exceeds 95.8%, and the lead and zinc volatilization rate exceeds 91.3%.

[0091] Comparative Example 1

[0092] Gypsum slag was dried to a moisture content of less than 15%, then ground in a mortar until it passed a 200-mesh sieve. The chemical composition of the gypsum slag, calculated by mass percentage, was as follows: Ca 28.0%, Mg 0.49%, K 0.033%, Fe 0.11%, Cd 0.010%, Cu 0.0005%, S 19.00%, and Pb 0.011%. 100g of bottom-blown copper slag from a smelter was collected and the composition, by mass percentage, was as follows: Fe 40.13%, Cu 3.25%, Pb 1.03%, Zn 3.65%, Ca 2.61%, and Si 11.59%. The copper slag was rapidly melted in an intermediate frequency furnace. Simultaneously, before the molten copper slag was transferred to a slag ladle for cooling, 9.16g of gypsum slag was added directly to the molten copper slag. After cooling in the slag ladle for 24 hours, a cooled slag sample was obtained.

[0093] Figure 7 The actual picture of the cooling slag sample prepared in Comparative Example 1 shows that no obvious stratification phenomenon and large copper matte particles were observed in the sample cross section. Without the use of plasma, the CaSO4 in the gypsum slag could not be decomposed into [S 2- ] form, and self-decomposes into CaO and SO2 at high temperature, resulting in the oxidized copper not being sulfided, and unable to make the small amount of matte in the slag aggregate and settle, so no stratification occurs. Figure 8 This is an SEM image of the cooled slag sample in Example 3. The test results show that the particle sizes of the Cu-Fe-S matte particles and Fe-S sulfide are both small. The copper slag particle size must be greater than 40 μm to meet the flotation requirements. The smaller matte particles lead to low grinding flotation efficiency, and there is no reducing atmosphere. Lead and zinc are present in the slag phase in the form of silicates.

[0094] In summary, the above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for recovering valuable metals from copper smelting slag, characterized in that: include: Before the molten copper smelting slag is transferred to a slag ladle for cooling, a first gas, gypsum slag, and nitrogen are added to the molten copper smelting slag by plasma injection. After the injection is completed, metal gas and copper slag are obtained. The copper slag is then post-treated and flotated to obtain a valuable metal matte phase and depleted slag. Wherein, the first gas is one or more of CO, H2, CO2, and CH4; The metal gaseous substances include gaseous lead and gaseous zinc; The valuable metal matte phase is sulfide of copper, iron, lead and zinc.

2. The method for recovering valuable metals from copper smelting slag according to claim 1, characterized in that: The steps of post-processing the copper slag include: cooling and grinding; The cooling time is 20 to 30 hours, and the powder particle size of the grinding is 35 to 100 μm.

3. The method for recovering valuable metals from copper smelting slag according to claim 1, characterized in that: The volume ratio of the first gas to nitrogen is 1:4 to 2:

3.

4. The method for recovering valuable metals from copper smelting slag according to claim 1, characterized in that: The amount of the first gas added is 1 to 5 times the amount of the lead and zinc compounds in the copper smelting slag that are completely reduced.

5. The method for recovering valuable metals from copper smelting slag according to claim 1, characterized in that: The mass of the gypsum slag is 1 to 5 times the theoretical amount of completely sulfided oxidized copper in the copper smelting slag.

6. The method for recovering valuable metals from copper smelting slag according to claim 1, characterized in that: Calculated by mass fraction, the chemical composition of the copper smelting slag is Fe 20-50%, Cu 0.2-6.0%, Pb 0.2-3.0%, and Zn 0.5-5.0%.

7. The method for recovering valuable metals from copper smelting slag according to claim 1, characterized in that: The gypsum slag includes desulfurized gypsum from a smelter and / or neutralized gypsum from wastewater; Among them, the main component of desulfurization gypsum slag is CaSO4·xH2O.

8. The method for recovering valuable metals from copper smelting slag according to claim 1, characterized in that: The temperature of the plasma is 2000-3500K, and the power density is 5-15kW / cm 2 , the plasma flow rate is 300~500L / min.

9. A device for recovering valuable metals from copper smelting slag, characterized in that: include: A copper smelting furnace, used for heating copper smelting slag into molten copper smelting slag; a slag chute connected to the discharge port of the copper smelting furnace and used for transferring the molten copper smelting slag; a plasma device, the spraying range of which covers the molten copper smelting slag in the slag chute, and is used to add gypsum slag and nitrogen to the molten copper smelting slag by plasma spraying; a slag ladle, located below the slag chute, for receiving and cooling molten copper smelting slag; The gas recovery device is installed at the position of the molten copper smelting slag in the plasma jet slag chute to collect the metal gas generated at the moment of plasma jetting.

10. The device for recovering valuable metals from copper smelting slag according to claim 9, characterized in that: The plasma device includes a plurality of plasma spray guns, which are distributed in a ring array, and 1 to 3 plasma spray guns are arranged at the discharge port of each cubic meter of the copper smelting furnace.

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