Method for smelting copper oxide ore and pyrite to produce crude copper

Abstract

The application discloses a method for preparing crude copper by smelting copper oxide ore and pyrite, and belongs to the technical field of non-ferrous metal smelting. The method comprises the following steps: (1) mixing, crushing and obtaining a mixture after the copper oxide ore, a reducing agent and a flux are mixed, wherein the reducing agent is pyrite concentrate; (2) pretreating the mixture obtained in the step (1) to obtain pretreated material; and (3) reducing and smelting the pretreated material obtained in the step (2) to obtain slag and crude copper. The method uses pyrite to replace carbonaceous reducing agents to prepare the crude copper by reducing and smelting the copper oxide ore, effectively alleviates the environmental protection pressure of copper smelting production units on the basis that the crude copper meets the quality requirements, reduces the comprehensive cost of preparing the crude copper, and prolongs the service life of equipment.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal smelting, specifically relating to a method for preparing crude copper by smelting copper oxide ore and pyrite. Background Technology

[0002] Copper, as a fundamental strategic metal, occupies an indispensable position in the modern industrial system. As the primary mineral resource for copper smelting, the grade of easily beneficiated copper sulfide ores has declined sharply with increasing copper consumption and usage time, and they face the risk of increasing depletion. Therefore, to maintain the supply and demand of copper, the importance of copper oxide ores with complex occurrence states and large grade fluctuations is becoming increasingly prominent.

[0003] However, while traditional hydrometallurgical processes (such as leaching-extraction-electrowinning) can process some copper oxide ores, they often suffer from disadvantages such as low leaching efficiency, increased reagent consumption, difficulty in solution purification, and high solid-liquid separation costs when dealing with complex ores with high-bonding copper oxide ores, high mud content, or associated alkaline gangue minerals (such as calcium and magnesium).

[0004] Pyrometallurgy, especially reduction smelting, has become a promising and important technological direction for processing copper oxide ore resources due to its advantages of strong raw material adaptability, large processing scale, relatively short process, and direct production of metallic phase products (crude copper). Reduction smelting is usually carried out at high temperature and in a strong reducing atmosphere, using carbonaceous reducing agents (such as coke, pulverized coal, or natural gas) to reduce copper in copper oxide minerals (such as malachite (Cu2CO3(OH)2), cuprite (Cu2O), azurite (Cu3(CO3)2(OH)2), etc.) to metallic copper (crude copper). At the same time, gangue components react with flux to form molten slag, thus realizing the production of crude copper from copper oxide ore as raw material.

[0005] However, the current process of preparing crude copper through reduction smelting of copper oxide ore presents several problems: ① Carbonaceous reducing agents easily cause excessive reduction of impurity elements in the copper oxide ore, even generating elemental substances that enter the crude copper, leading to an increase in impurity content. Simultaneously, the slag formed from gangue components (such as SiO2, Al2O3, CaO, and MgO) is quite viscous, resulting in poor separation between the slag and copper. This leads to lower copper content in the crude copper, making it prone to producing substandard crude copper products. More copper entering the slag results in higher reagent consumption and longer flotation time, increasing subsequent slag treatment costs and reducing efficiency. ② Currently, the reduction smelting process typically requires a smelting temperature of 1350-1450℃, resulting in high energy consumption and strong corrosiveness to smelting equipment. ③ Carbonaceous reducing agents contain a high amount of carbon (C), leading to high concentrations of harmful gases such as CO in the flue gas. This increases the difficulty of flue gas treatment, increasing environmental pressure on smelting production units and raising flue gas treatment costs.

[0006] Therefore, it is necessary to provide a method for smelting copper oxide ore and pyrite to prepare crude copper, reducing slag viscosity, improving the separation effect between slag and copper, and thus increasing the yield of crude copper products. Simultaneously, it lowers the smelting temperature, reduces energy consumption, alleviates the environmental pressure on smelting production units, and reduces flue gas treatment costs. Summary of the Invention

[0007] To overcome the problems in the prior art, this invention uses pyrite to replace carbonaceous reducing agents in the reduction smelting of copper oxide ore to prepare crude copper. This completely eliminates the problem of a significant increase in the generation of harmful gases such as CO caused by the consumption of reducing agents, alleviating the environmental pressure on smelting production units. At the same time, it reduces slag viscosity and smelting temperature, improves the separation effect between slag and crude copper, increases the purity of crude copper, reduces the rate of defective crude copper, reduces energy consumption, reduces the corrosive effect of the smelting process on equipment, and extends the service life of the equipment.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0009] This invention provides a method for preparing crude copper by smelting copper oxide ore and pyrite, the method comprising the following steps:

[0010] (1) The copper oxide ore, reducing agent and flux are mixed and crushed to obtain a mixture, wherein the reducing agent is pyrite concentrate;

[0011] The copper oxide ore contains, by mass fraction, 18%-28% Cu, <5% Fe, and <5% S;

[0012] The pyrite concentrate contains, by mass fraction, Fe > 30% and S > 35%;

[0013] The mass ratio of copper oxide ore to pyrite concentrate is calculated as CuO in copper oxide ore and FeS2 in pyrite concentrate, with CuO:FeS2 = 2.5-3.0:1.

[0014] (2) The mixture obtained in step (1) is pretreated to obtain pretreated material;

[0015] The specific process of the pretreatment is as follows: heating the mixture to 400-500℃ and holding it at that temperature for 0.5-1.5 hours;

[0016] (3) The pretreated material obtained in step (2) is subjected to reduction smelting to obtain slag and crude copper. After smelting, the slag and crude copper directly exhibit a good upper and lower stratification state.

[0017] Preferably, the main component of the copper oxide ore is malachite (Cu2CO3(OH)2).

[0018] Preferably, in step (1), the flux is a mixture of quartz and limestone, wherein the mass of quartz added is 2%-12% of the mass of copper oxide ore, and the mass of limestone added is 3%-10% of the mass of copper oxide ore.

[0019] Preferably, in step (1), the particle size of the crushed mixture is 100-150 mesh.

[0020] Preferably, in step (3), the reduction melting temperature is 1250-1300℃ and the reduction melting time is 1-3h.

[0021] Preferably, in step (3), the slag is crushed, flotated and recovered, and then returned to reduction smelting. The Fe / SiO2 mass ratio in the slag is Fe:SiO2 = 0.5-1.5:1, and the CaO mass fraction is 4%-8%.

[0022] Preferably, the flue gas generated in steps (2) and (3) is transported to the acid production process as a raw material for acid production after waste heat recovery and dust collection.

[0023] The beneficial effects of this invention are:

[0024] 1. This invention prepares crude copper by using pyrite as a carbonaceous reducing agent in the reduction smelting of copper oxide ore. During the smelting process, the iron element in pyrite exists in the slag in the form of fir olivine, which improves the slag type, reduces the slag viscosity, greatly promotes the efficient separation of slag and copper melt, reduces the mechanical inclusion of copper in the slag, allows more copper to enter the crude copper, increases the copper content in the crude copper, and improves the crude copper qualification rate.

[0025] 2. The iron element in pyrite exists in the slag in the form of fir olivine. The melting point of the fir olivine slag phase is significantly lower than that of traditional calcium-based slag or silicon-saturated slag, which allows the smelting process to be carried out at a lower temperature. This not only directly reduces energy consumption, but also reduces the erosion intensity of smelting equipment by high temperature, which is conducive to extending the service life of the equipment.

[0026] 3. SO2 is the most significant pollutant in the flue gas produced during pyrometallurgical copper smelting. It needs to be treated in conventional smelting processes. Usually, it is used as a raw material for acid production after conventional waste heat recovery and dust collection. The SO2 generated during the preparation process of this invention only needs to be treated in accordance with the conventional treatment methods for flue gas produced during pyrometallurgical copper smelting. No additional treatment methods or equipment are required, and it will not significantly increase the difficulty or cost of flue gas treatment for smelting production units.

[0027] 4. This invention utilizes the relatively weak reducing properties of pyrite to first reduce the copper oxide generated from the decomposition of copper oxide ore to cuprous oxide and cuprous sulfide, and then further convert them into elemental copper through the reaction of these two phases. This reduction path differs from the traditional method of directly reducing copper oxide to elemental copper with carbonaceous reducing agents. It can achieve targeted reduction of copper oxide, effectively reducing the probability of excessive reduction of impurity elements such as lead, zinc, arsenic, antimony, and bismuth in copper oxide ore, thereby significantly reducing the number of impurity elements entering the crude copper. This not only helps to improve the purity of crude copper, but also further improves the qualified rate of crude copper, while reducing the processing load and production cost of subsequent refining processes.

[0028] 5. The method of this invention can effectively reduce carbon emissions, fully respond to the "dual carbon" target, and has extremely significant strategic and environmental value for promoting the low-carbon transformation of the copper smelting industry and actively responding to global warming.

[0029] 6. The crude copper prepared by the method of the present invention contains Cu>98.5%, Fe<0.5%, and S<0.5%, and the quality of the crude copper meets the relevant standard requirements with a high pass rate. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described. Example 1

[0032] This embodiment prepares crude copper according to the following method:

[0033] (1) Take copper oxide ore (containing 25.35% Cu, 3.56% Fe, and 2.08% S) and pyrite concentrate (containing 43.61% Fe and 49.14% S) and mix them at a mass ratio of CuO:FeS2=2.7:1. Add quartz and limestone flux (where the mass of quartz added is 2% of the mass of copper oxide ore and the mass of limestone added is 3% of the mass of copper oxide ore), crush to a particle size of 100-150 mesh, and obtain a mixture (in the mixture, the mass percentage of material with a particle size of 100-150 mesh is 93%).

[0034] (2) The mixture is pretreated by keeping it at 400℃ for 1.5h to obtain pretreated material. At the same time, the smoke and dust generated in this process are recovered.

[0035] (3) The pretreated material is further heated to 1250℃ for reduction smelting for 3 hours to obtain slag and crude copper. The smoke and flue gas generated in this process are recovered, and the slag is returned to the smelting after crushing and flotation.

[0036] The smoke and flue gas generated during pretreatment and smelting are sent to the acid production process after waste heat recovery and dust collection.

[0037] The crude copper prepared in this embodiment contains 98.82% Cu, 0.23% Fe, and 0.31% S, which is a qualified product. The slag has an Fe / SiO2 ratio of 1.5:1 and a CaO content of 4%. Example 2

[0038] This embodiment prepares crude copper according to the following method:

[0039] (1) Take copper oxide ore (containing 20.67% Cu, 2.41% Fe, and 3.22% S) and pyrite concentrate (containing 40.02% Fe and 45.36% S) and mix them at a mass ratio of CuO:FeS2=3.0:1. Add quartz and limestone flux (where the mass of quartz added is 8% of the mass of copper oxide ore and the mass of limestone added is 7% of the mass of copper oxide ore), crush to a particle size of 100-150 mesh, and obtain a mixture (in the mixture, the mass percentage of material with a particle size of 100-150 mesh is 91%).

[0040] (2) The mixture is pretreated by keeping it at 450℃ for 1.0h to obtain pretreated material. At the same time, the dust and flue gas generated in this process are recovered.

[0041] (3) The pretreated material is further heated to 1270℃ for reduction smelting for 2.0h to obtain slag and crude copper. The dust and flue gas generated in this process are recovered, and the slag is returned to smelting after crushing and flotation.

[0042] The smoke and flue gas generated during pretreatment and smelting are sent to the acid production process after waste heat recovery and dust collection.

[0043] The crude copper prepared in this embodiment contains 98.74% Cu, 0.31% Fe, and 0.25% S, which is a qualified product. The slag has an Fe / SiO2 ratio of 1.1:1 and a CaO content of 6%. Example 3

[0044] This embodiment prepares crude copper according to the following method:

[0045] (1) Take copper oxide ore (containing 23.92% Cu, 3.83% Fe, and 2.45% S) and pyrite concentrate (containing 42.18% Fe and 36.73% S) and mix them at a mass ratio of CuO:FeS2=2.5:1. Add quartz and limestone flux (where the mass of quartz added is 12% of the mass of copper oxide ore and the mass of limestone added is 10% of the mass of copper oxide ore), crush to a particle size of 100-150 mesh, and obtain a mixture (in the mixture, the mass percentage of material with a particle size of 100-150 mesh is 94%).

[0046] (2) The mixture is pretreated by keeping it at 500℃ for 0.5h to obtain pretreated material. At the same time, the dust and flue gas generated in this process are recovered.

[0047] (3) The pretreated material is further heated to 1300℃ for reduction smelting for 1 hour to obtain slag and crude copper. The dust and flue gas generated in this process are recovered, and the slag is returned to the smelting after crushing and flotation.

[0048] The smoke and flue gas generated during pretreatment and smelting are sent to the acid production process after waste heat recovery and dust collection.

[0049] The crude copper prepared in this embodiment contains 98.67% Cu, 0.37% Fe, and 0.31% S, which is a qualified product. The slag has an Fe / SiO2 ratio of 0.5:1 and a CaO content of 8%.

[0050] In summary, this invention uses pyrite as a substitute for carbonaceous reducing agents in the reduction smelting of copper oxide ore to prepare crude copper. This method yields crude copper with a high copper content and low levels of impurities such as Fe and S, ensuring that the crude copper meets quality requirements while effectively alleviating the environmental pressure on copper smelting production units, reducing the overall cost of crude copper preparation, and extending the service life of equipment.

[0051] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and in detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for preparing crude copper by smelting copper oxide ore and pyrite, characterized in that: The method includes the following steps: (1) The copper oxide ore, reducing agent and flux are mixed and crushed to obtain a mixture, wherein the reducing agent is pyrite concentrate; The copper oxide ore contains, by mass fraction, 18%-28% Cu, <5% Fe, and <5% S; The pyrite concentrate contains, by mass fraction, Fe > 30% and S > 35%; The mass ratio of copper oxide ore to pyrite concentrate is calculated as CuO in copper oxide ore and FeS2 in pyrite concentrate, with CuO:FeS2 = 2.5-3.0:

1. (2) The mixture obtained in step (1) is pretreated to obtain pretreated material; The specific process of the pretreatment is as follows: heating the mixture to 400-500℃ and holding it at that temperature for 0.5-1.5 hours; (3) The pretreated material obtained in step (2) is subjected to reduction smelting to obtain slag and crude copper.

2. The method according to claim 1, characterized in that: In step (1), the flux is a mixture of quartz and limestone, wherein the mass of quartz added is 2%-12% of the mass of copper oxide ore, and the mass of limestone added is 3%-10% of the mass of copper oxide ore.

3. The method according to claim 1, characterized in that: In step (1), the particle size of the crushed mixture is 100-150 mesh.

4. The method according to claim 1, characterized in that: In step (3), the reduction melting temperature is 1250-1300℃ and the reduction melting time is 1-3h.

5. The method according to claim 1, characterized in that: In step (3), the slag is crushed, flotated and recovered and then returned to reduction smelting.

6. The method according to claim 1, characterized in that: The flue gas generated in steps (2) and (3) is transported to the acid production process as a raw material for acid production after waste heat recovery and dust collection.

Images