Method for preparing crude copper by smelting copper oxide ore and pyrite

Abstract

The invention 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 and crushing copper oxide ore, a reducing agent and a flux to obtain a mixed material, wherein the reducing agent is pyrite concentrate; (2) pretreating the mixed material obtained in the step (1) to obtain a pretreated material; and (3) the pretreated material obtained in the step (2) is subjected to reduction smelting, and slag and crude copper are obtained. The pyrite is used for replacing a carbonaceous reducing agent to carry out reduction smelting on the copper oxide ore to prepare the crude copper, on the basis of ensuring that the crude copper meets the quality requirement, the environmental protection pressure of a copper smelting production unit is effectively relieved, the comprehensive cost of crude copper preparation is reduced, and the service life of equipment is prolonged.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of non-ferrous metal smelting, and particularly relates to a method for preparing crude copper by smelting copper oxide ore and pyrite. BACKGROUND

[0002] Copper is a basic strategic metal and occupies an indispensable position in the modern industrial system. As the main mineral resources for smelting copper, with the increase of copper consumption and use time, the grade of easily smelted copper sulfide ore is rapidly decreasing and is facing the risk of exhaustion. Therefore, in order to maintain the supply and demand of copper, the importance of copper oxide ore resources with complex occurrence and large fluctuation in grade is increasingly prominent.

[0003] However, although the traditional hydrometallurgical process (such as leaching-extraction-electrodeposition) can process some copper oxide ores, when facing complex ores with high combined rate of copper oxide, high clay content or associated alkaline gangue minerals (such as calcium and magnesium), there are often disadvantages such as low leaching efficiency, dramatic increase of reagent consumption, difficulty in solution purification and high cost of solid-liquid separation.

[0004] Pyrometallurgy, especially reduction smelting process, has become an important technical direction for processing copper oxide ore resources due to its strong adaptability to raw materials, large processing scale, relatively short process and direct production of metal phase products (crude copper). Reduction smelting usually uses carbonaceous reducing agents (such as coke, coal powder or natural gas) to reduce copper in copper oxide minerals (such as malachite (Cu2CO3(OH)2), cuprite (Cu2O), blue copper (Cu3(CO3)2(OH)2) and the like) to metallic copper (crude copper) under high temperature and strong reducing atmosphere, while the gangue components react with flux to form molten slag, realizing the preparation of crude copper from copper oxide ore as raw material.

[0005] However, there are many problems in the process of preparing crude copper by reduction smelting of copper oxide ore at present: ① The carbonaceous reducing agent can easily cause excessive reduction of impurity elements in the copper oxide ore and even generate elemental substances to enter the crude copper, resulting in an increase in the impurity content in the crude copper. At the same time, the slag formed by the gangue components (such as SiO2, Al2O3, CaO and MgO) is relatively viscous, which leads to poor separation effect of the slag and copper, resulting in low copper content in the crude copper, easy occurrence of unqualified crude copper products, more copper entering the slag, and more reagents consumed and longer flotation time in the flotation process, causing the cost of subsequent slag treatment to increase and the treatment efficiency to decrease. ② The smelting temperature in the current reduction smelting process is usually 1350-1450℃, which has high energy consumption and strong corrosion to the smelting equipment. ③ The carbonaceous reducing agent contains a large amount of C element, which can cause the flue gas to be rich in high-concentration CO and other harmful gases, increase the difficulty of flue gas treatment, and increase the environmental protection pressure and the cost of flue gas treatment per unit of smelting production.

[0006] Therefore, it is necessary to provide a method for smelting copper oxide ore and pyrite to prepare crude copper, which reduces the viscosity of the slag, improves the separation effect of the slag and copper, thereby improving the qualified rate of the crude copper product. At the same time, the smelting temperature is reduced, the energy consumption is reduced, the environmental pressure of the smelting production unit is relieved, and the flue gas treatment cost is reduced. SUMMARY

[0007] In order to overcome the problems in the background art, the present application uses pyrite to replace carbonaceous reducing agent for reducing smelting of copper oxide ore to prepare crude copper, completely eliminates the problem of large increase in the amount of harmful gases such as CO caused by reducing agent consumption, relieves the environmental pressure of the smelting production unit, reduces the viscosity of the slag and the smelting temperature, improves the separation effect of the slag and crude copper, improves the purity of the crude copper, reduces the unqualified rate of the crude copper, reduces the energy consumption, reduces the erosion intensity of the equipment during the smelting process, and prolongs the service life of the equipment.

[0008] In order to achieve the above-mentioned purpose, the present application realizes the following technical scheme: The present application provides a method for smelting copper oxide ore and pyrite to prepare crude copper, which comprises the following steps: (1) mixing and crushing copper oxide ore, reducing agent and flux to obtain a mixture, wherein the reducing agent is pyrite concentrate; The copper oxide ore contains Cu: 18%-28%, Fe: <5%, and S: <5% by mass; The pyrite concentrate contains Fe: >30% and S: >35% by mass; The mass ratio of copper oxide ore to pyrite concentrate is CuO: FeS2 = 2.5-3.0:1, calculated based on CuO in the copper oxide ore and FeS2 in the pyrite concentrate; (2) pretreating the mixture obtained in step (1) to obtain a pretreated material; The specific process of the pretreatment is to heat the mixture to 400-500℃ and keep it at this temperature for 0.5-1.5h; (3) reducing smelting the pretreated material obtained in step (2) to obtain slag and crude copper. After smelting, the slag and crude copper directly present a good upper and lower layered state.

[0009] As a preferred embodiment, the main component of the copper oxide ore is malachite (Cu2CO3(OH)2).

[0010] As a preferred embodiment, in step (1), the flux is a mixture of quartz and limestone, 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.

[0011] Preferably, in step (1), the particle size of the crushed mixture is 100-150 mesh.

[0012] Preferably, in step (3), the reduction melting temperature is 1250-1300℃ and the reduction melting time is 1-3h.

[0013] Preferably, in step (3), the slag is crushed, flotated and recovered, and then returned to the smelting process for reduction. The Fe / SiO2 mass ratio in the slag is Fe:SiO2 = 0.5-1.5:1, and the CaO mass fraction is 4%-8%.

[0014] 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.

[0015] The beneficial effects of this invention are: 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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

[0021] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0022] 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

[0023] This embodiment prepares crude copper according to the following method: (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%).

[0024] (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.

[0025] (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.

[0026] The smoke and flue gas generated during pretreatment and smelting are sent to the acid production process after waste heat recovery and dust collection.

[0027] 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

[0028] This embodiment prepares crude copper according to the following method: (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%).

[0029] (2) The mixture is pretreated by keeping it at 450℃ for 1.0h to obtain pretreated material. At the same time, the smoke and dust generated in this process are recovered.

[0030] (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.

[0031] The smoke and flue gas generated during pretreatment and smelting are sent to the acid production process after waste heat recovery and dust collection.

[0032] 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

[0033] This embodiment prepares crude copper according to the following method: (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%).

[0034] (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.

[0035] (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.

[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 98.67% 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%.

[0038] 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.

[0039] 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.

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