Method for recovering copper matte from copper-poor smelting slag by injecting fly ash

Abstract

The present application relates to a kind of methods for recovering copper matte by injecting fly ash into copper smelting slag, belonging to pyrometallurgical technical field.The copper smelting slag (slag-sulfide mixture) is added to the lean electric furnace and heated to 1100~1300℃, so that the copper smelting slag is heated to molten state to obtain copper smelting slag melt;Fly ash is used as reducing agent and slagging agent, and fly ash powder is sprayed into copper smelting slag melt through a spray gun for reaction, and copper matte and waste slag are obtained after natural settlement and separation, completing the lean process of copper smelting slag, and the waste slag is recycled.The present application optimizes the existing copper smelting slag lean process in electric furnace, which can ensure the continuity of copper smelting process and realize efficient recovery of copper matte.

Description

Technical Field

[0001] This invention relates to a method for recovering copper matte from copper smelting slag by injecting fly ash, which belongs to the field of pyrometallurgical technology. Background Technology

[0002] Copper smelting slag is an unavoidable non-ferrous metal smelting slag produced during copper smelting. Its copper content can reach over 5%, approaching or slightly exceeding the exploitable grade of existing copper ore. Excessive copper content in the slag is a major cause of significant copper loss during oxygen-enriched smelting. With the increasing depletion of high-grade copper ore resources, the sources of copper concentrate entering the furnace are diverse and complex, leading to problems such as unstable composition, unreasonable slag shape, poor fluidity, and high copper content in the smelting slag. To reduce copper loss caused by slag discarding, copper smelting slag depletion has become a necessary step in the oxygen-enriched copper smelting process.

[0003] Electric arc furnace (EAF) slag depletion technology is widely used in industry due to its advantages such as strong raw material adaptability, short process, high copper recovery rate (copper content in waste slag is only 0.4%–1%), and full utilization of slag heat. However, the large amount of magnetic iron in copper smelting slag increases its viscosity, severely affecting the recovery of copper matte. During the smelting process, the magnetic iron needs to be reduced. Commonly used reducing agents in EAF slag depletion include coal, coke, diesel, biomass, and some industrial waste. The large amounts of fossil-based reducing agents such as pulverized coal, natural gas, and diesel not only consume additional resources but also release large amounts of greenhouse gases that damage the ecological environment. Furthermore, EAF slag depletion often requires the separate addition of slag-forming agents such as quartz and limestone, which undoubtedly increases smelting costs and makes resource recycling difficult. Summary of the Invention

[0004] To address the problems of existing copper smelting slag depletion processes in electric arc furnaces, this invention proposes a method for recovering copper matte from copper smelting slag through fly ash injection. This invention uses fly ash as both a reducing agent and a slag-forming agent to deplete copper smelting slag discharged from an oxygen-enriched smelting furnace in an electric arc furnace. The fly ash reduces the magnetic iron in the copper smelting slag and provides components such as CaO, SiO2, MgO, and Al2O3 for slag formation, thereby reducing melt viscosity, promoting the sedimentation and enrichment of copper matte particles, and increasing the copper matte recovery rate to over 95%. This method solves problems such as high copper loss from copper smelting slag, high consumption of fossil reducing agents and conventional slag-forming agents, and significant environmental risks.

[0005] A method for recovering copper matte from copper smelting slag by injecting fly ash, characterized by the following specific steps: (1) Add copper smelting slag (slag-matte mixture) into a depleted electric furnace and heat it to 1100~1300℃ to heat the copper smelting slag to a molten state to obtain copper smelting slag melt; (2) Using fly ash as a reducing agent and slag-forming agent, fly ash powder is sprayed into the copper smelting slag melt through a spray gun to react. After natural sedimentation and separation, copper matte and waste slag are obtained, completing the copper smelting slag depletion process. The waste slag is then used for resource utilization.

[0006] In step (2), the fly ash contains 1-20% fixed carbon, 30-50% SiO2, 10-20% CaO, 4-10% MgO, and 15-20% Al2O3 by mass.

[0007] The mass ratio of fly ash in step (2) to copper smelting slag in step (1) is (0.05~0.15):1.

[0008] The beneficial effects of this invention are: (1) This invention uses industrial solid waste fly ash as a reducing agent and slag-forming agent, without the need to add additional carbonaceous reducing agent and conventional slag-forming agent; the unburned carbon in fly ash can reduce Fe3O4 in copper smelting slag to FeO, and fly ash can also provide the calcium, silicon and aluminum components required for slag formation, thereby simplifying the silicate network structure in copper smelting slag, reducing the viscosity of the melt, achieving the purpose of improving the settling and enrichment environment of copper matte, and further improving the copper matte recovery rate; (2) The present invention can reduce the volume and resource utilization of fly ash while efficiently depleting copper smelting slag; it has significant advantages such as low cost, low energy consumption and good environmental benefits. Detailed Implementation

[0009] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0010] Example 1: By mass percentage, the copper smelting slag composition in this example is Cu: 17.82%, Fe: 33.06%, MgO: 1.95%, SiO2: 19.13%, Al2O3: 2.96%, CaO: 2.12%; the fly ash contains C: 2.55%, MgO: 6.57%, SiO2: 35.01%, Al2O3: 19.28%, CaO: 12.05%. A method for recovering copper matte from copper smelting slag by injecting fly ash, the specific steps of which are as follows: (1) Add copper smelting slag (slag-matte mixture) into a depleted electric furnace and heat it to 1200°C to heat the copper smelting slag to a molten state to obtain copper smelting slag melt; (2) Fly ash is used as a reducing agent and slag-forming agent to provide the carbonaceous material required for the copper smelting slag depletion process and the calcium and silicon elements required for slag formation. No additional carbonaceous reducing agent or conventional slag-forming agent is required. The fly ash powder is sprayed into the copper smelting slag melt through a spray gun for reaction. After natural sedimentation and separation for 60 minutes, copper matte and waste slag are obtained, completing the copper smelting slag depletion process. The waste slag can be used as building material for resource utilization. The mass ratio of the fly ash powder to the copper smelting slag in step (1) is 0.05:1. In this embodiment, the copper matte recovery rate is 95%.

[0011] Example 2: By mass percentage, the copper smelting slag composition in this example is Cu: 16.93%, Fe: 38.55%, MgO: 2.36%, SiO2: 23.15%, Al2O3: 2.50%, CaO: 3.15%; the fly ash contains C: 2.55%, MgO: 6.57%, SiO2: 35.01%, Al2O3: 19.28%, CaO: 12.05%. A method for recovering copper matte from copper smelting slag by injecting fly ash, the specific steps of which are as follows: (1) Add copper smelting slag (slag-matte mixture) into a depleted electric furnace and heat it to 1300°C to heat the copper smelting slag to a molten state to obtain copper smelting slag melt; (2) Fly ash is used as a reducing agent and slag-forming agent to provide the carbonaceous material required for the copper smelting slag depletion process and the calcium and silicon elements required for slag formation. No additional carbonaceous reducing agent or conventional slag-forming agent is required. The fly ash powder is sprayed into the copper smelting slag melt through a spray gun for reaction. After natural sedimentation and separation for 70 minutes, copper matte and waste slag are obtained, completing the copper smelting slag depletion process. The waste slag can be used as building material for resource utilization. The mass ratio of the fly ash powder to the copper smelting slag in step (1) is 0.10:1. In this embodiment, the copper matte recovery rate is 96%.

[0012] Example 3: By mass percentage, the copper smelting slag composition in this example is Cu: 18.35%, Fe: 36.45%, MgO: 1.25%, SiO2: 20.53%, Al2O3: 3%, CaO: 2.75%; the fly ash contains C: 2.55%, MgO: 6.57%, SiO2: 35.01%, Al2O3: 19.28%, CaO: 12.05%. A method for recovering copper matte from copper smelting slag by injecting fly ash, the specific steps of which are as follows: (1) Add copper smelting slag (slag-matte mixture) into a depleted electric furnace and heat it to 1250°C to heat the copper smelting slag to a molten state to obtain copper smelting slag melt; (2) Fly ash is used as a reducing agent and slag-forming agent to provide the carbonaceous material required for the copper smelting slag depletion process and the calcium and silicon elements required for slag formation. No additional carbonaceous reducing agent or conventional slag-forming agent is required. The fly ash powder is sprayed into the copper smelting slag melt through a spray gun for reaction. After natural sedimentation and separation for 80 minutes, copper matte and waste slag are obtained, completing the copper smelting slag depletion process. The waste slag can be used as building material for resource utilization. The mass ratio of the fly ash powder to the copper smelting slag in step (1) is 0.15:1. In this embodiment, the copper matte recovery rate is 97%.

[0013] Example 4: By mass percentage, the copper smelting slag composition in this example is Cu: 18.59%, Fe: 35.84%, MgO: 1.07%, SiO2: 21.22%, Al2O3: 2.86%, CaO: 2.64%; the fly ash contains C: 2.98%, MgO: 6.31%, SiO2: 34.88%, Al2O3: 17.53%, CaO: 13.34%. A method for recovering copper matte from copper smelting slag by injecting fly ash, the specific steps of which are as follows: (1) Add copper smelting slag (slag-matte mixture) into a depleted electric furnace and heat it to 1280°C to heat the copper smelting slag to a molten state to obtain copper smelting slag melt; (2) Fly ash is used as a reducing agent and slag-forming agent to provide the carbonaceous material required for the copper smelting slag depletion process and the calcium and silicon elements required for slag formation. No additional carbonaceous reducing agent or conventional slag-forming agent is required. The fly ash powder is sprayed into the copper smelting slag melt through a spray gun for reaction. After natural sedimentation and separation for 60 minutes, copper matte and waste slag are obtained, completing the copper smelting slag depletion process. The waste slag can be used as building material for resource utilization. The mass ratio of the fly ash powder to the copper smelting slag in step (1) is 0.15:1. In this embodiment, the copper matte recovery rate is 96%.

[0014] Example 5: By mass percentage, the copper smelting slag composition in this example is Cu: 17.62%, Fe: 37.28%, MgO: 1.03%, SiO2: 20.56%, Al2O3: 3.12%, CaO: 2.63%; the fly ash contains C: 2.75%, MgO: 6.33%, SiO2: 35.42%, Al2O3: 18.76%, CaO: 11.30%. A method for recovering copper matte from copper smelting slag by injecting fly ash, the specific steps of which are as follows: (1) Add copper smelting slag (slag-matte mixture) into a depleted electric furnace and heat it to 1200°C to heat the copper smelting slag to a molten state to obtain copper smelting slag melt; (2) Fly ash is used as a reducing agent and slag-forming agent to provide the carbonaceous material required for the copper smelting slag depletion process and the calcium and silicon elements required for slag formation. No additional carbonaceous reducing agent or conventional slag-forming agent is required. The fly ash powder is sprayed into the copper smelting slag melt through a spray gun for reaction. After natural sedimentation and separation for 120 minutes, copper matte and waste slag are obtained, completing the copper smelting slag depletion process. The waste slag can be used as building material for resource utilization. The mass ratio of the fly ash powder to the copper smelting slag in step (1) is 0.13:1. In this embodiment, the copper matte recovery rate is 95%.

[0015] Compared with the direct reduction of copper smelting slag using anthracite, the method of this invention makes full use of the unburned carbon in fly ash to reduce Fe3O4 in copper smelting slag to FeO, and provides some of the calcium, silicon and aluminum components required for slag formation, thereby simplifying the silicate network structure in copper smelting slag, reducing melt viscosity, causing copper matte particles to grow larger, and further improving the copper matte recovery rate. Therefore, the copper matte recovery rate is significantly higher than that of anthracite.

[0016] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for recovering copper matte from copper smelting slag by injecting fly ash, characterized in that, The specific steps are as follows: (1) Add copper smelting slag into a depleted electric furnace and heat it to 1100~1300℃ to heat the copper smelting slag to a molten state to obtain copper smelting slag melt; (2) Using fly ash as a reducing agent and slag-forming agent, fly ash powder is sprayed into the copper smelting slag melt through a spray gun for reaction. After natural sedimentation and separation, copper matte and waste slag are obtained, completing the copper smelting slag depletion process. The waste slag is then used for resource utilization. The fly ash contains 1-20% fixed carbon, 30-50% SiO2, 10-20% CaO, 4-10% MgO, and 15-20% Al2O3. The mass ratio of fly ash powder to copper smelting slag in step (1) is (0.05-0.15):1.