A method for reducing and recovering valuable metals from low-grade copper-containing solid waste materials

Abstract

The present invention provides a method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials. This method involves proportioning the low-grade copper-containing solid waste materials with at least one slag-forming agent such as quartzite, limestone, and iron particles, as well as coke, and performing reduction smelting on the mixture using a vertical high-temperature smelting furnace. By controlling the conditions of the reduction process, most of the copper oxides in the smelting slag are reduced to metallic copper, which aggregates with precious metals such as gold and silver to form coarse copper particles. The density of the coarse copper particles is greater than that of the slag, so they quickly sink in the foam layer and settle into the coarse copper layer, while the impurity metal oxides are not reduced and remain in the slag phase. The method proposed by the present invention can effectively overcome the disadvantages of low comprehensive recovery rate, long process flow, and high furnace condition control requirements in the prior art for low-grade copper-containing solid waste slag, achieving the maximum comprehensive recovery and utilization of copper and precious metal resources, and having good economic and environmental benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive recovery and utilization of secondary resources of non-ferrous metals, and particularly relates to a method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials. Background Art

[0002] With the rapid development of technology, the update and iteration of electronic products have accelerated, and the number of waste electronic products has increased day by day. The core component in electronic waste is the circuit board. The waste circuit board not only contains valuable metals such as copper, gold, and silver but also harmful heavy metal elements, and is listed in the National Hazardous Waste List (No. 900-045-49). If not utilized, it will not only cause waste of valuable metals but also pollute the environment.

[0003] Most of the treatment processes for copper-containing solid waste residues adopt pyrometallurgical processes. Existing pyrometallurgical processes generally include closed blast furnace smelting process, Ausmelt furnace smelting process, flash furnace smelting process, Kaldo furnace smelting process, side-blown furnace smelting process, bottom-blown furnace smelting process, etc. At present, according to the characteristics of these smelting processes themselves, there are still disadvantages in the comprehensive recovery of low-grade copper-containing solid waste, such as low recovery rate, long process flow, low raw material adaptability, serious secondary pollution, and high requirements for furnace condition control.

[0004] In view of this, it is necessary to design an improved method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials.

[0006] To achieve the above-mentioned invention purpose, the present invention provides a method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials, including the following steps:

[0007] Mix the low-grade copper-containing solid waste material to be treated with a slag-forming agent and coke to obtain a mixed material; add the mixed material into the furnace through the charging port at the top of the vertical smelting furnace, and adopt the method of reduction smelting to reduce the copper oxide in the low-grade copper-containing solid waste material to metallic copper and enter the crude copper phase, while the impurity metal oxides are not reduced and remain in the slag phase; after the smelting is completed, discharge the crude copper phase from the copper discharge port at the top of the vertical smelting furnace, and discharge part of the slag phase from the slag discharge port at the top of the vertical smelting furnace;

[0008] The low-grade copper-containing solid waste material is low-grade copper-containing solid waste smelting slag or a mixture of copper-containing smelting slag, waste circuit board, waste miscellaneous copper, and electroplating sludge.

[0009] Preferably, when the low-grade copper-containing solid waste material is low-grade copper-containing solid waste smelting slag, the ingredients are prepared according to the composition of high-silicon and high-calcium furnace slag, and the mass fraction of iron in the high-silicon and high-calcium furnace slag is 21-25%, the mass fraction of silicon dioxide is 34-45%, the mass fraction of calcium oxide is 18-25%, and the mass fraction of aluminum is <10%.

[0010] Preferably, when the low-grade copper-containing solid waste material is a mixture, the ingredients are blended according to the slag type composition, and the mass fraction of iron in the obtained mixture after batching is 18-25%, the mass fraction of silicon dioxide is 28-35%, the mass fraction of calcium oxide is 15-22%, and the mass fraction of aluminum is <10%.

[0011] Furthermore, when the low-grade copper-containing solid waste material is low-grade copper-containing solid waste smelting slag, the valuable metals therein are recovered by reduction according to the following steps:

[0012] S1. According to the slag composition of high-silicon and high-calcium furnace slag, low-grade copper-containing solid waste smelting slag is mixed with a slag-making agent and coke, and the mass fraction of iron in the mixed material after mixing is 21-25%, the mass fraction of silicon dioxide is 34-45%, the mass fraction of calcium oxide is 18-25%, and the mass fraction of aluminum is less than 10%;

[0013] S2, after the mixed material in step S1 is put into a vertical smelting furnace, natural gas and process air are introduced into the furnace through a smelting spray gun, and the mixed material is quickly drawn into the molten pool for smelting and slag-making reaction under the stirring of the airflow at the outlet of the spray gun, and the liquid level of the molten pool is controlled at 1100mm. When the liquid level reaches 1100mm, stop adding copper-containing materials and only add reducing coke for reduction;

[0014] S3, measuring the height of the molten pool liquid level by a probe rod and determining the reduction end point and reduction time according to the composition and morphology of the reduction slag at the upper and middle part of the probe rod;

[0015] S4. When the reduction end point is reached through the detection rod, stop adding the reducing coke, reduce the amount of natural gas to the flow rate of the insulation state, raise the smelting spray gun to the parking position of the smelting furnace for insulation, and let it settle for 5-20 minutes;

[0016] S5, performing copper discharge operation from the copper discharge port, and performing slag discharge operation from the slag discharge port.

[0017] Preferably, in step S2, the total amount of mixed material fed into the furnace is 4-6 t / h, the copper grade in the mixed material is 3-10%, the amount of coke in the reduction smelting process is 0.9-1.1 t / h, and the amount of natural gas is 450-550 m 3 / h, process weight is 5700-6200m 3 / h, the ratio of natural gas to process air volume is 1:10 - 1:14, and the residual oxygen concentration in the flue gas is 1 - 4%.

[0018] Preferably, in step S3, when reaching the reduction end point, the slag sample on the surface of the detection rod is in the shape of wire mesh mercury and the thickness of the foam layer in the molten bath is 300 - 1000 mm.

[0019] Furthermore, when the low-grade copper-containing solid waste material is a mixture of copper smelting slag, waste circuit boards, scrap copper, and electroplating sludge, the valuable metals therein are recovered by reduction according to the following steps:

[0020] (1) Crush large waste circuit boards and scrap copper into small-sized furnace feed materials, steam-dry and granulate the wet and powdery electroplating sludge into granular materials, and sort out large visible aluminum.

[0021] (2) According to the slag type composition of the furnace slag, mix the raw materials treated in step (1) with slag formers and coke. The mass fraction of iron in the mixed material after batching is 18 - 25%, the mass fraction of silicon dioxide is 28 - 35%, the mass fraction of calcium oxide is 15 - 25%, and the mass fraction of aluminum is < 10%.

[0022] (3) After putting the mixed material in step (2) into the vertical smelting furnace, introduce natural gas and process air or oxygen into the furnace through the smelting spray gun. The materials are quickly drawn into the interior of the molten bath by the agitation of the gas flow at the spray gun outlet for smelting slag formation reaction, and control the molten bath liquid level at 1100 mm.

[0023] (4) Analyze the appearance morphology of the oxidized smelting slag in step (3) or conduct X-ray fluorescence composition analysis, and timely adjust the dosage of the slag former according to the analysis results and experience to accurately control the slag type composition of the furnace slag in step (2).

[0024] (5) After step (4) ends, stop adding the batching, only add reduction coke, keep the distance between the spray gun port and the molten bath liquid level above 150 - 250 cm, and spray a mixture of natural gas and process air in a certain proportion through the spray gun, so that most of the copper oxides in the smelting slag are reduced to metallic copper and enter the crude copper phase, while the impurity metal oxides are not reduced and remain in the slag phase.

[0025] (6) After step (5) ends, stop adding reduction coke, reduce the natural gas volume to the heat preservation state flow rate, lift the smelting spray gun to the docking position in the smelting furnace for heat preservation, and let it stand and settle for 10 - 20 min.

[0026] (7) Conduct copper discharging operation from the copper discharging port and slag discharging operation from the slag discharging port.

[0027] Preferably, in step (3), the total amount of mixed material fed into the furnace is 6-8 t / h, the copper grade in the mixed material is 5-30%, the amount of coke is 0.4-0.8 t / h, and the amount of natural gas is 230-350 m 3 / h, process air volume is 6200-6700m 3 / h, the ratio of natural gas to process air volume is 1:18-1:30, and the residual oxygen concentration in flue gas is 5-8%.

[0028] Preferably, in step (5), the strong reducing atmosphere is obtained by controlling the amount of reducing coke to 0.8-1.0 t / h and the amount of natural gas to 400-500 m 3 / h, process air volume is 5700-6200m 3 / h, the ratio of natural gas to process air volume is 1:11-1:16, and the residual oxygen concentration in flue gas is 3-5%.

[0029] Preferably, in step (5), when the reduction end point is reached, the slag sample on the surface of the probe rod is in the shape of a wire mesh mercury and the thickness of the foam layer in the molten pool is 100-300 mm.

[0030] Preferably, in step (6), the natural gas flow rate is 200-300m 3 / h, process air volume is 2000-3000m 3 / h, the ratio of natural gas to process air volume is 1:10.

[0031] The beneficial effects of the present invention are:

[0032] The present invention provides a method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials. The method comprises mixing low-grade copper-containing solid waste materials with at least one slag-forming agent selected from quartz, limestone, and iron particles, and coke, and reducing and smelting the mixture in a vertical high-temperature smelting furnace; by controlling the conditions of the reduction process, most of the copper oxides in the smelting slag are reduced to metallic copper, and aggregated with rare and precious metals such as gold and silver to form crude copper particles. The crude copper particles have a greater density than the slag, and rapidly descend in the foam layer and sink into the crude copper layer, while the impurity metal oxides are not reduced and remain in the slag phase. The method proposed by the present invention can effectively overcome the shortcomings of the prior art of low comprehensive recovery rate of low-grade copper-containing solid waste slag, long process, and high requirements for furnace condition control, and realizes the maximum comprehensive recovery and utilization of copper and rare and precious metal resources, with good economic and environmental benefits. The method proposed in the present invention overcomes the shortcomings of the prior art of low comprehensive recovery rate of low-grade copper-containing solid waste slag, long process and high requirements for furnace condition control, and is suitable for the reduction and recovery of valuable metals in single low-grade copper-containing solid waste smelting slag and a mixture of low-grade copper-containing solid waste smelting slag, achieving the maximum comprehensive recovery and utilization of copper and rare precious metal resources, and has good economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic flow chart of the method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials proposed by the present invention;

[0034] Figure 2 It is another schematic flow chart of the method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials proposed by the present invention;

[0035] Figure 3 It is a schematic structural diagram of the vertical smelting furnace adopted in Embodiments 1-10 of the present invention;

[0036] The reference numerals are as follows: 1. Vertical smelting furnace; 2. Smelting spray gun; 3. Probe rod; 4. Feeding port; 5. Slag discharge port; 6. Copper discharge port. Detailed implementation manners

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Here, it should also be noted that in order to avoid obscuring the present invention due to unnecessary details, only the structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, while other details less related to the present invention are omitted.

[0039] In addition, it should also be noted that the term "comprises", "comprising" or any other variant thereof is intended to cover a non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0040] The method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials provided by the present invention includes the following steps:

[0041] Mix the low-grade copper-containing solid waste materials to be processed with a slag-forming agent and coke to obtain a mixed material; add the mixed material into the furnace through the feeding port 4 at the top of the vertical smelting furnace 1, and adopt the method of reduction smelting to reduce the copper oxide in the low-grade copper-containing solid waste materials to metallic copper and enter the crude copper phase, while the impurity metal oxides are not reduced and remain in the slag phase; after the smelting is completed, discharge the crude copper phase from the copper discharge port 6. To prevent the formation of a frozen layer at the furnace bottom, the crude copper phase should not be completely discharged, and a part of the crude copper phase needs to be reserved to prevent slag formation. Discharge a part of the slag phase from the slag discharge port 5 to start the next round of strong reduction smelting and slag formation after the slag discharge is completed.

[0042] As an embodiment of the present invention, the vertical smelting furnace 1 includes a furnace body. The top of the furnace body is provided with a flue outlet and a feeding port 4, the bottom of the furnace body is provided with a slag discharge port 5 and a copper discharge port 6. Inside the furnace body, there are a smelting spray gun 2 and a detection rod 3 that penetrate the inner wall of the furnace body and extend to the lower part of the furnace body. The smelting spray gun 2 is used to introduce natural gas and process air into the furnace, and the detection rod 3 is used to measure the liquid level height in the furnace and analyze the composition and morphology of the reducing slag at the middle and upper positions of the detection rod 3 to determine the reduction end point and reduction time; the temperature of the vertical smelting furnace 1 is 1280 - 1350 °C. In some embodiments, the vertical smelting furnace 1 is 10 - 20 m high, and the distance between the bottom end of the smelting spray gun 2 and the liquid level in the furnace is 150 - 250 cm. It should be noted that in some other embodiments, the size of the vertical smelting furnace 1 and the installation position of the smelting spray gun 2 can also be adjusted according to needs, as long as the requirements can be met, and it is not limited hereby.

[0043] As an embodiment of the present invention, the low-grade copper-containing solid waste material is low-grade copper-containing smelting slag or a mixture of copper-containing smelting slag, waste circuit boards, waste miscellaneous copper, and electroplating sludge, and the slag former is at least one of quartz stone, limestone, and iron pellets. When the low-grade copper-containing solid waste material is low-grade copper-containing smelting slag, batching is carried out according to the slag type composition of high-silicon high-calcium furnace slag. In the slag type of high-silicon high-calcium furnace slag, the mass fraction w(Fe) of iron is 21 - 25%, the mass fraction w(SiO2) of silicon dioxide is 34 - 45%, the mass fraction w(CaO) of calcium oxide is 18 - 25%, and the mass fraction w(Al) of aluminum < 10%; when the low-grade copper-containing solid waste material is a mixture, batching is carried out according to the slag type composition of the furnace slag. After batching, the mass fraction w(Fe) of iron in the obtained mixture is 18 - 25%, the mass fraction w(SiO2) of silicon dioxide is 28 - 35%, the mass fraction w(CaO) of calcium oxide is 15 - 22%, and the mass fraction w(Al) of aluminum < 10%.

[0044] Further, please refer to Figure 1 As shown, when the low-grade copper-containing solid waste material is low-grade copper-containing smelting slag, the valuable metals therein are recovered by reduction according to the following steps:

[0045] S1. Batching: According to the slag type composition of high-silicon high-calcium furnace slag, batch the low-grade copper-containing smelting slag with the slag former and coke. After batching, the mass fraction w(Fe) of iron in the mixture is 21 - 25%, the mass fraction w(SiO2) of silicon dioxide is 34 - 45%, the mass fraction w(CaO) of calcium oxide is 18 - 25%, and the mass fraction w(Al) of aluminum < 10%;

[0046] S2. Foam reduction smelting: After putting the mixture in step S1 into the vertical smelting furnace 1, natural gas and process air are introduced into the furnace through the smelting spray gun 2. The materials are quickly involved in the internal of the molten pool by the agitation of the gas flow at the spray gun outlet to carry out the smelting slag-making reaction. The reaction process proceeds according to the following equation: 2MeO + SiO2 = 2MeO·SiO2, where natural gas is used as the heat source and process air is the combustion promoter. This process controls the strong reduction atmosphere for strong reduction smelting by controlling the spray gun end pressure, reduction coke amount, reduction natural gas amount, reduction process air amount, and reduction time, so that most of the copper oxides in the smelting slag are reduced to metallic copper and enter the blister copper phase, while the impurity metal oxides are not reduced and remain in the slag phase. Control the molten pool liquid level at 1100 mm. When the liquid level reaches 1100 mm, stop adding copper-containing materials and only add reduction coke for reduction.

[0047] S3. Judgment of reduction end point: Measure the molten pool liquid level through the probe rod 3 and determine the reduction end point and reduction time by analyzing the composition and morphology of the reduction slag at the middle and upper positions of the probe rod 3.

[0048] S4. Static settling: When the reduction end point is detected by the probe rod 3, stop adding reduction coke, reduce the natural gas amount to the heat preservation state flow rate, lift the smelting spray gun 2 to the docking position in the smelting furnace for heat preservation, and carry out static settling for 5 - 30 min.

[0049] S5. Blister copper discharging and slag discharging: Carry out the blister copper discharging operation from the blister copper outlet 6. Relying on the pressure of the slag layer helps to discharge the blister copper phase. To prevent the formation of a frozen layer at the furnace bottom, the blister copper phase should not be completely discharged, and a part of the blister copper phase needs to be reserved to prevent slag formation. Carry out the slag discharging operation from the slag outlet 5, and also reserve a part of the slag phase. After the slag discharging is completed, add the batching again to start the next round of strong reduction smelting and slag-making.

[0050] In the above technical solution, by mixing the low-grade copper-containing solid waste smelting slag with at least one slag-making agent such as quartzite, limestone, and iron particles and coke for batching, and adding it to the top of the vertical high-temperature smelting furnace, the materials fall to the furnace bottom and are quickly melted in the molten pool under the agitation of the mixed gas flow of the smelting spray gun. Through controlling the slag surface height, reduction coke amount, natural gas amount, natural gas / process air volume ratio, spray gun end pressure, and reduction time, strong reduction smelting is carried out on the smelting slag. Since the high-silica and high-calcium slag type has a relatively large viscosity, a foam layer is easily generated in the molten slag during strong reduction smelting, increasing the surface area of the molten slag and strengthening the gas-solid two-phase kinetic conditions, which is conducive to the occurrence of reduction reactions. By controlling the thickness of the reduction smelting slag foam layer, most of the copper oxides in the smelting slag are reduced to metallic copper, aggregated with precious metals such as gold and silver into blister copper particles. The blister copper particles have a higher density than the molten slag and quickly sink to the blister copper layer in the foam layer, while the impurity metal oxides are not reduced and remain in the slag phase.

[0051] Preferably, in step S1, before batching, the melting slag needs to be pretreated according to its size. If it is large-sized slag, it needs to be crushed into small pieces of 1 - 20 cm. If it is powdered material, it needs to be dried and granulated to facilitate batching and the subsequent reduction process.

[0052] Preferably, in step S2, during the reduction smelting process, the coke amount is 0.9 - 1.1 t / h, the natural gas amount is 450 - 550 m 3 / h, the process air volume is 5700 - 6200 m 3 / h, the ratio of natural gas to process air volume is 1:10 - 1:14, and the residual oxygen concentration in the flue gas is 1 - 4%. During the above process, due to the relatively high viscosity of the high-calcium and high-silicon slag, the molten slag is prone to generating a foam layer, increasing the surface area of the molten slag, strengthening the gas-solid two-phase kinetic conditions, and facilitating the reduction reaction. By controlling the thickness of the foam layer of the reduction smelting slag, most of the copper oxides in the smelting slag are reduced to metallic copper, and precious metals such as gold and silver are collected and aggregated into granular form. The density of the crude copper particulate matter is greater than that of the molten slag, and it quickly descends in the foam layer and sinks into the crude copper layer, while the impurity metal oxides are not reduced and remain in the slag phase.

[0053] Preferably, in step S2, the process air volume can protect the smelting lance 2 from high-temperature melting, and the minimum process air volume shall not be lower than 5500 m 3 / h.

[0054] Preferably, in step S3, when reaching the reduction end point, the slag sample on the surface of the probe 3 is in the shape of wire mesh mercury, and the thickness of the molten pool foam layer is 300 - 1000 mm. The foam layer can be quickly eliminated by controlling the ratio of the heat-preserving natural gas to the process air at 1:10 - 1:13.

[0055] Preferably, in step S3, the analysis of the composition and morphology of the reduction slag is sampled by the probe 3, and the direction of slag type adjustment is preliminarily judged according to the physical state conditions of the slag on the probe 3, such as the undercooked state, thickness, color, magnetism, weight, etc.

[0056] Preferably, in step S4, during the heat preservation process, the natural gas flow rate is 200 - 300 m 3 / h, the process air volume is in the same proportion of 2000 - 3000 m 3 / h, and the gas / air ratio is introduced at 1:10 to ensure the full combustion of natural gas.

[0057] Further, please refer to Figure 2 As shown, when the low-grade copper-containing solid waste material is a mixture of copper smelting slag, waste circuit boards, waste miscellaneous copper, and electroplating sludge, the valuable metals in it are recovered by reduction according to the following steps:

[0058] (1) Pretreatment of raw materials: Break large waste circuit boards and waste miscellaneous copper into small pieces of 5 - 20 cm as furnace charge materials. Steam-dry and granulate the wet and powdery electroplating sludge into granular materials with a diameter of 1 - 5 cm, and sort out large visible aluminum;

[0059] (2) Batching: According to the slag type composition of the furnace slag, batch the raw materials treated in step (1) with slag formers and coke. After batching, the mass fraction w(Fe) of iron in the mixed material is 18 - 25%, the mass fraction w(SiO2) of silicon dioxide is 28 - 35%, the mass fraction w(CaO) of calcium oxide is 15 - 25%, and the mass fraction w(Al) of aluminum < 10%;

[0060] (3) Weak oxidation smelting and slag formation: After putting the mixed material in step (2) into the vertical smelting furnace 1, introduce natural gas and process air or oxygen into the furnace through the smelting spray gun 2. The materials are quickly drawn into the interior of the molten pool by the agitation of the gas flow at the spray gun outlet for smelting and slag formation reaction. The reaction process proceeds according to the following equation: 2MeO + SiO2 = 2MeO·SiO2, where natural gas is used as the heat source and process air and oxygen are combustion aids; in this process, the impurity metals in the materials are oxidized into the slag phase by controlling the weak oxidation atmosphere, and most of the metallic copper is not oxidized and sinks into the crude copper phase, controlling the molten pool liquid level at 1100 mm;

[0061] (4) Process control: Analyze the appearance morphology of the oxidized smelting slag in step (3) or conduct X-ray fluorescence composition analysis, and adjust the dosage of the slag former in a timely manner according to the analysis results and experience to accurately control the slag type composition of the furnace slag in step (2);

[0062] (5) Strong reduction smelting: After step (4) ends, stop adding the batch materials, only add reduction coke, keep the distance between the spray gun port and the molten pool liquid level above 150 - 250 cm, and spray a mixture of natural gas and process air in a certain proportion through the spray gun. Conduct strong reduction smelting on the formed copper-containing smelting slag by controlling the spray gun port depth, spray gun stirring intensity, reduction coke amount, reduction natural gas amount, and reduction time to control the strong reduction atmosphere, so that most of the copper oxides in the smelting slag are reduced to metallic copper and enter the crude copper phase, while the impurity metal oxides are not reduced and remain in the slag phase;

[0063] (6) Static settling: After step (5) ends, stop adding reduction coke, reduce the natural gas volume to the heat preservation state flow rate, lift the smelting spray gun 2 to the docking position of the smelting furnace for heat preservation, and conduct static settling for 5 - 30 min;

[0064] (7) Copper and slag discharging: Conduct copper discharging operation from the copper discharging port 6. Relying on the pressure of the slag layer helps to discharge the blister copper phase. To prevent the formation of a frozen layer at the furnace bottom, not all of the blister copper phase should be discharged, and a part of the blister copper phase needs to be reserved to prevent slag formation. Conduct slag discharging operation from the slag discharging port 5, and also reserve a part of the slag phase. After the slag discharging is completed, add the batching again to start the next round of strong reduction smelting and slag formation.

[0065] In the above technical solution, after mixing low-grade copper-containing materials such as waste circuit boards and electroplating sludge with at least one slag-forming agent among quartzite, limestone, and iron pellets and coke for batching, it is added to the top of the vertical high-temperature smelting furnace. After the materials fall to the furnace bottom, they are involved in the molten pool and quickly melted under the agitation of the mixed gas flow of the smelting spray gun. By controlling the weak oxidation atmosphere, most of the impurity metal elements are oxidized and enter the slag layer, and most of the copper is not oxidized. Because the density of copper is greater than that of the molten slag, it sinks into the blister copper layer, and precious and rare metals such as gold and silver enter the blister copper layer synergistically under the wrapping of copper. According to the X-ray fluorescence analysis results of the smelting slag composition and empirical judgment, timely adjust the dosage of the slag-forming agent to accurately control the slag type composition of the furnace slag, and conduct strong reduction smelting on the oxidized copper by controlling the strong reduction atmosphere, so that most of the copper oxides in the smelting slag are reduced to metallic copper and precious and rare metals such as gold and silver are collected again into the blister copper layer, while the impurity metal oxides are not reduced. After standing for a period of time, the blister copper phase rich in precious and rare metals is stratified from the slag phase.

[0066] More preferably, in step (3), the weak oxidation atmosphere means that under the condition of ensuring that the mixed materials can be fully melted, the oxygen partial pressure is slightly excessive. Specifically: when the total amount of the charged mixture is 6 - 8 t / h, the copper grade in the mixture is 5 - 30%, the coke amount is 0.4 - 0.8 t / h, the natural gas amount is 230 - 350 m 3 / h, the process air volume is 6200 - 6700 m 3 / h, the ratio of natural gas to process air volume is 1:18 - 1:30, and the residual oxygen concentration in the flue gas is 5 - 8%.

[0067] More preferably, in step (3), the process air volume can protect the smelting spray gun 2 from high-temperature melting, and the minimum process air volume shall not be lower than 5500 m 3 / h.

[0068] More preferably, in step (5), the strong reduction atmosphere is achieved by controlling the reduction coke amount to 0.8 - 1.0 t / h, the natural gas amount to 400 - 500 m 3 / h, the process air volume to 5700 - 6200 m 3 / h, the ratio of natural gas to process air volume to 1:11 - 1:16, and the residual oxygen concentration in the flue gas to 3 - 5%.

[0069] More preferably, in step (6), the natural gas flow rate in the heat preservation state is 200 - 300 m 3 / h, the process air volume is 2000 - 3000 m 3 / h, and the ratio of natural gas to process air volume is 1:10 to ensure complete combustion of natural gas.

[0070] The following further describes the method for reducing and recovering valuable metals in low - grade copper - containing solid waste materials proposed by the present invention in combination with specific embodiments:

[0071] In the following embodiments, the process of reducing and recovering valuable metals in low - grade copper - containing solid waste materials is realized by means of a vertical smelting furnace 1, and its structural schematic diagram is as Figure 3 shown. The vertical smelting furnace 1 includes a furnace body. At the top of the furnace body, there are a flue gas outlet and a feeding port 4. At the bottom of the furnace body, there are a slag discharge port 5 and a copper discharge port 6. Inside the furnace body, there are a smelting spray gun 2 and a detection rod 3 that penetrate the inner wall of the furnace body and extend to the lower part of the furnace body. The smelting spray gun 2 is used to introduce natural gas and process air into the furnace, and the detection rod 3 is used to measure the liquid level height in the furnace and analyze the composition and morphology of the reducing slag at the upper - middle position of the detection rod 3 to determine the reduction end point and reduction time; the vertical smelting furnace 1 is 14 m high, and the distance between the bottom end of the smelting spray gun 2 and the liquid surface in the furnace is 200 mm. It should be noted that in some other embodiments, the height of the vertical smelting furnace 1 and the installation position of the smelting spray gun 2 can also be adjusted according to needs as long as the requirements can be met, and this is not limited herein.

[0072] Example 1

[0073] This example proposes a method for reducing and recovering valuable metals in low - grade copper - containing solid waste materials. The low - grade copper - containing solid waste material is low - grade copper - containing solid waste smelting slag. The specific reduction and recovery method is as follows:

[0074] Mix the low - grade copper - containing solid waste smelting slag with quartz stone, limestone, iron pellets, and coke. After mixing, the mass fraction of iron w(Fe) in the mixed material is 21%, the mass fraction of silicon dioxide w(SiO2) is 34%, the mass fraction of calcium oxide w(CaO) is 18%, and the mass fraction of aluminum w(Al) < 10% of the slag type composition; add the mixed material into the vertical smelting furnace 1 through the feeding port 4, control the molten pool liquid level to be 1100 mm, the distance between the port of the smelting spray gun 2 and the liquid surface in the molten pool is 200 mm, the end pressure of the spray gun 2 is 14 kPa, the furnace temperature is 1290 °C, the total input amount is 5 t / h, the copper grade in the furnace is 8%, the coke amount is 0.8 t / h, control the natural gas amount to be 320 m 3 / h, the process air volume is 6200 m 3 / h, and conduct strong reduction smelting with the residual oxygen concentration in the flue gas being 4%; after stopping feeding, only add coke for reduction, the coke amount is 0.9 t / h, the natural gas amount is 450 m 3 / h, the process air volume is 6100 m 3 / h, the residual oxygen concentration of the flue gas is 3%. After reduction for 15 minutes under this reduction condition, the thickness of the foam layer on the molten bath slag surface is 300 mm. After standing and settling for 15 minutes, a crude copper alloy rich in rare and precious metals with a copper content of 98.34% and a water-quenched slag with a copper content of 0.27% are obtained from the copper discharge port 6 and the slag discharge port 5 respectively.

[0075] Example 2

[0076] This example presents a method for reducing and recovering valuable metals from low-grade copper-containing solid waste materials. The low-grade copper-containing solid waste materials are low-grade copper-containing solid waste smelting slag. The specific reduction and recovery method is as follows:

[0077] Mix the low-grade copper-containing solid waste smelting slag with quartzite, limestone, iron pellets, and coke. After batching, the mass fraction of iron w(Fe) in the mixed material is 23%, the mass fraction of silicon dioxide w(SiO2) is 36%, the mass fraction of calcium oxide w(CaO) is 19%, and the mass fraction of aluminum w(Al) < 10% of the slag type composition; add the mixed material into the vertical smelting furnace 1 from the charging port 4, control the molten bath liquid level to be 1100 mm, the distance between the port of the smelting spray gun 2 and the liquid surface in the molten bath is 200 mm, the end pressure of the spray gun 2 is 14 kPa, the furnace temperature is 1290 °C, the total charging amount is 5 t / h, the copper grade in the furnace is 7%, the coke amount is 0.9 t / h, control the natural gas amount to be 330 m 3 / h, the process air volume is 6200 m 3 / h, conduct strong reduction smelting with a residual oxygen concentration of 4% in the flue gas; after stopping feeding, only add coke for reduction, the coke amount is 1.0 t / h, the natural gas amount is 480 m 3 / h, the process air volume is 6100 m 3 / h, the residual oxygen concentration of the flue gas is 2%. After reduction for 13 minutes under this reduction condition, the thickness of the foam layer on the molten bath slag surface is 500 mm. After standing and settling for 15 minutes, a crude copper alloy rich in rare and precious metals with a copper content of 98.62% and a water-quenched slag with a copper content of 0.24% are obtained from the copper discharge port 6 and the slag discharge port 5 respectively.

[0078] Example 3

[0079] This example presents a method for reducing and recovering valuable metals from low-grade copper-containing solid waste materials. The low-grade copper-containing solid waste materials are low-grade copper-containing solid waste smelting slag. The specific reduction and recovery method is as follows:

[0080] Mix low-grade copper-containing solid waste smelting slag with quartz, limestone, iron pellets and coke. After batching, the mass fraction of iron w(Fe) in the mixed material is 23%, the mass fraction of silicon dioxide w(SiO2) is 38%, the mass fraction of calcium oxide w(CaO) is 20%, and the mass fraction of aluminum w(Al) < 10% of the slag type composition; Add the mixed material into the vertical smelting furnace 1 from the feeding port 4, control the molten pool liquid level to be 1100 mm, the distance between the port of the smelting spray gun 2 and the liquid surface in the molten pool is 200 mm, the end pressure of the spray gun 2 is 15 kpa, the furnace temperature is 1300 °C, the total amount of material entering the furnace is 5 t / h, the copper grade entering the furnace is 6%, the coke amount is 1.0 t / h, control the natural gas amount to be 340 m 3 / h, the process air volume is 6100 m 3 / h, and perform strong reduction smelting with the flue gas residual oxygen concentration of 3%; After stopping feeding, only add coke for reduction, the coke amount is 1.0 t / h, the natural gas amount is 500 m 3 / h, the process air volume is 5900 m 3 / h, the flue gas residual oxygen concentration is 2%, and after reducing for 10 min under this reduction condition, the thickness of the foam layer on the molten pool slag surface is 700 mm. Let it stand and settle for 20 min, and obtain a crude copper alloy rich in rare precious metals with a copper content of 98.55% and a water-quenched slag with a copper content of 0.21% from the copper discharge port 6 and the slag discharge port 5 respectively.

[0081] Example 4

[0082] This example proposes a method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials. The low-grade copper-containing solid waste material is low-grade copper-containing solid waste smelting slag. The specific reduction and recovery method is as follows:

[0083] Mix low-grade copper-containing solid waste smelting slag with quartz, limestone, iron pellets and coke. After batching, the mass fraction of iron w(Fe) in the mixed material is 23%, the mass fraction of silicon dioxide w(SiO2) is 39%, the mass fraction of calcium oxide w(CaO) is 21%, and the mass fraction of aluminum w(Al) < 10% of the slag type composition; Add the mixed material into the vertical smelting furnace 1 from the feeding port 4, control the molten pool liquid level to be 1100 mm, the distance between the port of the smelting spray gun 2 and the liquid surface in the molten pool is 200 mm, the end pressure of the spray gun 2 is 15 kpa, the furnace temperature is 1320 °C, the total amount of material entering the furnace is 5 t / h, the copper grade entering the furnace is 5%, the coke amount is 1.0 t / h, control the natural gas amount to be 340 m 3 / h, the process air volume is 5900 m 3 / / h, and perform strong reduction smelting with the flue gas residual oxygen concentration of 3%; After stopping feeding, only add coke for reduction, the coke amount is 1.0 t / h, the natural gas amount is 500 m 3 / h, the process air volume is 5800 m 3 / h, the residual oxygen concentration of the flue gas is 2%. After reduction for 10 min under this reduction condition, the thickness of the foam layer on the molten bath slag surface is 800 mm. After standing and settling for 25 min, a crude copper alloy rich in rare and precious metals with a copper content of 98.77% and a water-quenched slag with a copper content of 0.18% are obtained from the copper discharge port 6 and the slag discharge port 5 respectively.

[0084] Example 5

[0085] This example proposes a method for reducing and recovering valuable metals from low-grade copper-containing solid waste materials. The low-grade copper-containing solid waste materials are low-grade copper-containing smelting slag. The specific reduction and recovery method is as follows:

[0086] Mix the low-grade copper-containing smelting slag with quartzite, limestone, iron pellets and coke. After batching, the mass fraction of iron w(Fe) in the mixed material is 23%, the mass fraction of silicon dioxide w(SiO2) is 42%, the mass fraction of calcium oxide w(CaO) is 22%, and the mass fraction of aluminum w(Al) < 10% of the slag type composition; add the mixed material into the vertical smelting furnace 1 from the feeding port 4, control the molten bath liquid level to be 1100 mm, the distance between the port of the smelting spray gun 2 and the liquid surface in the molten bath is 200 mm, the end pressure of the spray gun 2 is 15 kPa, the furnace temperature is 1350 °C, the total feeding amount is 5 t / h, the copper grade in the furnace is 3%, the coke amount is 1.0 t / h, control the natural gas amount to be 350 m 3 / h, the process air volume is 5900 m 3 / h, conduct strong reduction smelting with a residual oxygen concentration of 2% in the flue gas; after stopping the feeding, only add coke for reduction, the coke amount is 1.0 t / h, and the natural gas amount is 550 m 3 / h, the process air volume is 5700 m 3 / h, the residual oxygen concentration of the flue gas is 2%. After reduction for 5 min under this reduction condition, the thickness of the foam layer on the molten bath slag surface is 1000 mm. After standing and settling for 30 min, a crude copper alloy rich in rare and precious metals with a copper content of 98.88% and a water-quenched slag with a copper content of 0.13% are obtained from the copper discharge port 6 and the slag discharge port 5 respectively.

[0087] Example 6

[0088] This example proposes a method for reducing and recovering valuable metals from low-grade copper-containing solid waste materials. The low-grade copper-containing solid waste materials are a mixture of copper-containing smelting slag, waste circuit boards, waste miscellaneous copper and electroplating sludge. The specific reduction and recovery method is as follows:

[0089] Mix copper-containing smelting slag, waste circuit boards, scrap copper, electroplating sludge with quartzite, limestone, iron pellets and coke. After batching, the mass fraction w(Fe) of iron in the mixed material is 21%, the mass fraction w(SiO₂) of silicon dioxide is 31%, the mass fraction w(CaO) of calcium oxide is 17%, and the mass fraction w(Al) of aluminum is <10% of the slag type composition; add the mixed material into the vertical smelting furnace 1 from the feeding port 4, control the molten pool liquid level at 1100 mm, the distance between the port of the smelting spray gun 2 and the liquid surface in the molten pool is 200 mm, the furnace temperature is 1345 °C, the total feeding amount is 8 t / h, the copper grade in the furnace is 5%, the coke amount is 0.8 t / h, control the natural gas amount at 350 m 3 / h, and carry out weak oxidation smelting with the residual oxygen concentration in the flue gas being 5%; control the reduction coke amount at 1.0 t / h, the natural gas amount at 500 m 3 / h, the process air volume is 5700 m 3 / h, the residual oxygen concentration in the flue gas is 3%. Under this reduction condition, after reducing for 5 min, the thickness of the foam layer on the molten pool slag surface is 300 mm, and let it stand and settle for 15 min. Obtain a crude copper alloy rich in rare precious metals with a copper content of 98.15% and a water-quenched slag with a copper content of 0.44% from the copper discharge port 6 and the slag discharge port 5 respectively.

[0090] Example 7

[0091] This example proposes a method for reducing and recovering valuable metals from low-grade copper-containing solid waste materials. The low-grade copper-containing solid waste materials are a mixture of copper-containing smelting slag, waste circuit boards, scrap copper, and electroplating sludge. The specific reduction and recovery method is as follows:

[0092] Mix copper-containing smelting slag, waste circuit boards, scrap copper, electroplating sludge with quartzite, limestone, iron pellets and coke. After batching, the mass fraction w(Fe) of iron in the mixed material is 22%, the mass fraction w(SiO₂) of silicon dioxide is 32%, the mass fraction w(CaO) of calcium oxide is 18%, and the mass fraction w(Al) of aluminum is <10% of the slag type composition; add the mixed material into the vertical smelting furnace 1 from the feeding port 4, control the molten pool liquid level at 1100 mm, the distance between the port of the smelting spray gun 2 and the liquid surface in the molten pool is 200 mm, the furnace temperature is 1340 °C, the total feeding amount is 8 t / h, the copper grade in the furnace is 8%, the coke amount is 0.7 t / h, control the natural gas amount at 330 m 3 / h, and carry out weak oxidation smelting with the residual oxygen concentration in the flue gas being 5%; control the reduction coke amount at 0.9 t / h, the natural gas amount at 480 m 3 / h, the process air volume is 5800 m 3 / h, the residual oxygen concentration of the flue gas is 3%. After reduction for 8 minutes under this reduction condition, the thickness of the foam layer on the molten bath slag surface is 250 mm. After standing and settling for 15 minutes, a crude copper alloy rich in rare and precious metals with a copper content of 98.73% and a water-quenched slag with a copper content of 0.45% are obtained from the copper discharge port 6 and the slag discharge port 5 respectively.

[0093] Example 8

[0094] This example presents a method for reducing and recovering valuable metals from low-grade copper-containing solid waste materials. The low-grade copper-containing solid waste materials are a mixture of copper smelting slag, waste circuit boards, waste miscellaneous copper, and electroplating sludge. The specific reduction and recovery method is as follows:

[0095] Charge the copper smelting slag, waste circuit boards, waste miscellaneous copper, electroplating sludge, quartz stone, limestone, iron pellets, and coke. After batching, the mass fraction of iron w(Fe) in the mixed material is 22%, the mass fraction of silicon dioxide w(SiO2) is 31%, the mass fraction of calcium oxide w(CaO) is 17%, and the mass fraction of aluminum w(Al) < 10% of the slag type composition; Add the mixed material into the vertical smelting furnace 1 from the charging port 4, control the molten bath liquid level at 1100 mm, the distance between the port of the smelting spray gun 2 and the liquid surface in the molten bath is 200 mm, the furnace temperature is 1330 °C, the total charging amount is 7 t / h, the copper grade in the furnace is 10%, the coke amount is 0.7 t / h, control the natural gas amount at 310 m 3 / h, and conduct weak oxidation smelting with a residual oxygen concentration of 6% in the flue gas; Control the reduction coke amount at 0.8 t / h and the natural gas amount at 460 m 3 / h, and the process air volume is 5900 m 3 / h, the residual oxygen concentration of the flue gas is 4%. After reduction for 12 minutes under this reduction condition, the thickness of the foam layer on the molten bath slag surface is 200 mm. After standing and settling for 15 minutes, a crude copper alloy rich in rare and precious metals with a copper content of 98.52% and a water-quenched slag with a copper content of 0.46% are obtained from the copper discharge port 6 and the slag discharge port 5 respectively.

[0096] Example 9

[0097] This example presents a method for reducing and recovering valuable metals from low-grade copper-containing solid waste materials. The low-grade copper-containing solid waste materials are a mixture of copper smelting slag, waste circuit boards, waste miscellaneous copper, and electroplating sludge. The specific reduction and recovery method is as follows:

[0098] Mix copper-containing smelting slag, waste circuit boards, scrap copper, electroplating sludge with quartz stone, limestone, iron pellets and coke. After batching, the mass fraction w(Fe) of iron in the mixed material is 23%, the mass fraction w(SiO₂) of silicon dioxide is 33%, the mass fraction w(CaO) of calcium oxide is 19%, and the mass fraction w(Al) of aluminum is <10% of the slag type composition; Add the mixed material into the vertical smelting furnace 1 from the feeding port 4, control the molten pool liquid level at 1100 mm, the distance between the port of the smelting spray gun 2 and the liquid surface in the molten pool is 200 mm, the furnace temperature is 1310 °C, the total amount charged into the furnace is 6 t / h, the copper grade charged into the furnace is 15%, the coke amount is 0.6 t / h, control the natural gas amount at 300 m 3 / h, and carry out weak oxidation smelting with the flue gas residual oxygen concentration of 7%; Control the reduction coke amount at 0.8 t / h, the natural gas amount at 450 m 3 / h, the process air volume is 6000 m 3 / h, the flue gas residual oxygen concentration is 5%. After reducing for 18 min under this reduction condition, the thickness of the foam layer on the molten pool slag surface is 150 mm. Let it stand and settle for 15 min, and obtain a crude copper alloy rich in rare precious metals with a copper content of 97.88% and a water-quenched slag with a copper content of 0.47% from the copper discharge port 6 and the slag discharge port 5 respectively.

[0099] Example 10

[0100] This example proposes a method for reducing and recovering valuable metals from low-grade copper-containing solid waste materials. The low-grade copper-containing solid waste materials are a mixture of copper-containing smelting slag, waste circuit boards, scrap copper, and electroplating sludge. The specific reduction and recovery method is as follows:

[0101] Mix copper-containing smelting slag, waste circuit boards, scrap copper, electroplating sludge with quartz stone, limestone, iron pellets and coke. After batching, the mass fraction w(Fe) of iron in the mixed material is 24%, the mass fraction w(SiO₂) of silicon dioxide is 32%, the mass fraction w(CaO) of calcium oxide is 19%, and the mass fraction w(Al) of aluminum is <10% of the slag type composition; Add the mixed material into the vertical smelting furnace 1 from the feeding port 4, control the molten pool liquid level at 1100 mm, the distance between the port of the smelting spray gun 2 and the liquid surface in the molten pool is 200 mm, the furnace temperature is 1290 °C, the total amount charged into the furnace is 5 t / h, the copper grade charged into the furnace is 20%, the coke amount is 0.6 t / h, control the natural gas amount at 280 m 3 / h, and carry out weak oxidation smelting with the flue gas residual oxygen concentration of 8%; Control the reduction coke amount at 0.8 t / h, the natural gas amount at 430 m 3 / h, the process air volume is 6100 m 3 / h, the residual oxygen concentration of the flue gas is 6%. After reduction for 25 minutes under this reduction condition, the thickness of the foam layer on the molten bath slag surface is 100 mm. After standing and settling for 15 minutes, a crude copper alloy with a copper content of 97.03% rich in rare and precious metals and a water-quenched slag with a copper content of 0.49% are obtained from the copper discharge port 6 and the slag discharge port 5 respectively.

[0102] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials, characterized in that: The steps include: The low-grade copper-containing solid waste to be treated is mixed with a slag-forming agent and coke to obtain a mixture; the mixture is added into the furnace through the charging port on the top of the vertical smelting furnace, and the copper oxide in the low-grade copper-containing solid waste is reduced to metallic copper and enters the crude copper phase by a reduction smelting method, while the impurity metal oxide is not reduced and remains in the slag phase; after the smelting is completed, the crude copper phase is discharged from the copper discharge port on the top of the vertical smelting furnace, and part of the slag phase is discharged from the slag discharge port on the top of the vertical smelting furnace; The low-grade copper-containing solid waste material is low-grade copper-containing solid waste smelting slag or a mixture of copper-containing smelting slag and waste circuit boards, waste copper, and electroplating sludge, and the slag-making agent is quartz stone, limestone, and iron particles; When the low-grade copper-containing solid waste material is low-grade copper-containing solid waste smelting slag, the valuable metals therein are recovered by reduction according to the following steps: S1. According to the slag composition of high-silicon and high-calcium furnace slag, low-grade copper-containing solid waste smelting slag is mixed with a slag-making agent and coke, and the mass fraction of iron in the mixed material after mixing is 21-25%, the mass fraction of silicon dioxide is 34-45%, the mass fraction of calcium oxide is 18-25%, and the mass fraction of aluminum is less than 10%; S2, after the mixed material in step S1 is put into a vertical smelting furnace, natural gas and process air are introduced into the furnace through a smelting spray gun, and the mixed material is quickly drawn into the molten pool for smelting and slag-making reaction under the stirring of the airflow at the outlet of the spray gun, and the liquid level of the molten pool is controlled at 1100mm. When the liquid level reaches 1100mm, stop adding copper-containing materials and only add reducing coke for reduction; during the reduction process, the total amount of mixed material entering the furnace is 4-6t / h, the copper grade in the mixed material is 3-10%, the amount of coke in the reduction smelting process is 0.9-1.1t / h, and the amount of natural gas is 450-550m 3 / h, process air volume is 5700-6200m 3 / h, the ratio of natural gas to process air volume is 1:10-1:14, and the residual oxygen concentration of flue gas is 1-4%; S3, measuring the height of the molten pool liquid level by a probe rod and determining the reduction end point and reduction time according to the composition and morphology of the reduction slag at the upper and middle part of the probe rod; when the reduction end point is reached, the slag sample on the surface of the probe rod is in the shape of wire mesh mercury and the thickness of the foam layer in the molten pool is 300-1000mm; S4. When the reduction end point is reached by the detection rod, stop adding the reducing coke, reduce the amount of natural gas to the flow rate of the insulation state, raise the smelting spray gun to the docking position of the smelting furnace for insulation, and let it settle for 5-30 minutes; S5, performing copper discharge operation from the copper discharge port, and performing slag discharge operation from the slag discharge port; When the low-grade copper-containing solid waste material is a mixture of copper-containing smelting slag, waste circuit boards, waste copper, and electroplating sludge, the valuable metals therein are recovered by reduction according to the following steps: (1) Large pieces of waste circuit boards and waste copper are crushed into small pieces for feeding into the furnace, the wet and powdery electroplating sludge is steam dried and granulated into granular materials, and large pieces of visible aluminum are sorted out; (2) according to the slag type composition, the raw materials treated in step (1) are mixed with a slag-forming agent and coke, wherein the mass fraction of iron in the mixed material is 18-25%, the mass fraction of silicon dioxide is 28-35%, the mass fraction of calcium oxide is 15-25%, and the mass fraction of aluminum is less than 10%; (3) After the mixed material in step (2) is put into a vertical smelting furnace, natural gas and process air or oxygen are introduced into the furnace through a smelting spray gun. The mixed material is quickly drawn into the molten pool for smelting and slag forming reaction under the stirring of the airflow at the outlet of the spray gun, and the liquid level of the molten pool is controlled at 1100mm; when the total amount of the mixed material entering the furnace is 6-8t / h, the copper grade in the mixed material is 5-30%, the amount of coke is 0.4-0.8t / h, and the amount of natural gas is 230-350m 3 / h, process air volume is 6200-6700m 3 / h, the ratio of natural gas to process air volume is 1:18-1:30, and the residual oxygen concentration of flue gas is 5-8%; (4) Analyze the appearance morphology of the oxidized smelting slag in step (3) or perform X-ray fluorescence composition analysis, and timely adjust the amount of slag-forming agent added based on the analysis results and experience to accurately control the slag type composition of the slag in step (2); (5) After step (4) is completed, stop adding ingredients and only add reducing coke, keep the spray gun port 150-250 cm above the molten pool liquid surface, and spray a certain proportion of natural gas and process air mixture through the spray gun, so that most of the copper oxides in the smelting slag are reduced to metallic copper and enter the crude copper phase, while the impurity metal oxides are not reduced and remain in the slag phase; the amount of coke in the reduction process is 0.8-1.0 t / h, and the amount of natural gas is 400-500m 3 / h, process air volume is 5700-6200m 3 / h, the ratio of natural gas to process air volume is 1:11-1:16, and the residual oxygen concentration of flue gas is 3-5%; (6) After step (5) is completed, stop adding reducing coke, reduce the amount of natural gas to a flow rate in a heat preservation state, raise the smelting lance to the parking position of the smelting furnace for heat preservation, and let it stand for 5-30 minutes; (7) copper discharge operation is performed from the copper discharge port, and slag discharge operation is performed from the slag discharge port.

2. The method for reducing and recovering valuable metals in low-grade copper-containing solid waste materials according to claim 1, characterized in that: In step (6), the natural gas flow rate is 200-300m 3 / h, process air volume is 2000-3000m 3 / h, the ratio of natural gas to process air volume is 1:10.

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