Method for realizing iron cycle and copper intensified recovery in one-step copper smelting process of low-iron copper concentrate

Abstract

The application discloses a method for realizing iron circulation and copper reinforced recovery in a one-step copper smelting process of low-iron copper concentrate, which comprises the following steps: directly pouring smelting slag produced by mixing low-iron copper concentrate with iron ore powder and smelting by a one-step copper smelting method into a reduction smelting furnace, adding appropriate amount of reducing agent blocks and slagging agents, forming copper-iron alloy after reduction and purification, and naturally separating and settling the copper-iron alloy in the furnace, returning the obtained copper-containing molten iron at the lower layer to a flash smelting furnace for reuse, and directly selling the upper layer molten slag after water quenching as tailing slag. The application returns the copper-containing molten iron at the lower layer to the furnace, solves the problem that the copper-iron alloy is difficult to apply, replaces part of iron-containing raw materials for slagging, realizes iron circulation, returns the molten liquid directly, avoids heat loss as much as possible, indirectly saves energy consumption, and makes the melts more easily contact, which is beneficial to smelting and slagging reactions.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for achieving iron recycling and enhanced copper recovery in a one-step copper smelting process of low-iron copper concentrate. Background Technology

[0002] In the field of copper smelting, the one-step copper smelting process combines "matte making and smelting" and "copper matte blowing" into a single furnace, which can significantly shorten the copper smelting process and has received widespread attention. However, because the one-step copper smelting method directly produces crude copper, the oxygen potential of the smelting furnace is higher than that of traditional smelting furnaces, resulting in a copper content in the slag exceeding 10% and the presence of a large amount of difficult-to-select elemental copper, which greatly increases the pressure on slag copper beneficiation.

[0003] One-step copper smelting slag typically requires electric furnace depletion, followed by slow slag cooling, crushing and grinding, and finally mineral processing to obtain copper concentrate and tailings with a copper content below 0.3%. Clearly, existing copper smelting slag treatment processes have the following shortcomings: 1) Complex process flow; 2) Significant sensible heat is dissipated to the external environment during the slow cooling stage, making it difficult to utilize; 3) The slag becomes very hard after cooling, resulting in high crushing and grinding costs; 4) Since a large portion of the copper in one-step copper smelting slag exists in a metallic state, flotation is difficult, making it hard to control the copper content of the tailings below 0.3% in actual processing. Furthermore, for high-copper-content copper concentrates, the iron content is relatively low. One-step copper smelting requires the addition of iron-containing materials for slag formation, but the added iron is lost with the tailings and cannot be reused, increasing material consumption costs.

[0004] Chinese patent CN 115011806A discloses a method for deep depletion of copper slag with low carbon content. This method directly reduces copper and iron in copper smelting slag to a copper-iron alloy, avoiding the complex processes of slow cooling, crushing, grinding, and flotation of copper slag. However, the resulting copper-iron alloy has a severely excessive copper content, making it unsuitable as a raw material for steelmaking. Therefore, the product obtained after consuming a large amount of reducing agent is difficult to utilize. Furthermore, this method adds 45% to 125% of the slag mass as a slag-forming agent, significantly increasing the slag processing capacity. Summary of the Invention

[0005] The purpose of this invention is to provide a method for achieving iron recycling and enhanced copper recovery in a one-step copper smelting process using low-iron copper concentrate.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for achieving iron recycling and enhanced copper recovery in a one-step copper smelting process using low-iron copper concentrate includes the following steps:

[0008] a) Mix low-iron copper concentrate with an appropriate amount of iron ore powder to achieve an iron-silicon ratio of 0.4 to 0.5. At the same time, add 6% to 8% of calcium oxide by weight of the low-iron copper concentrate. Then, smelt the concentrate in a flash furnace in one step to produce smelting slag and crude copper.

[0009] b) The obtained smelting slag is fed into a reduction smelting furnace, and a certain amount of reducing agent blocks and slag-forming agent are added and mixed. After a period of depletion and reduction, the generated copper-iron alloy naturally settles and separates in the furnace. The copper-containing molten iron obtained from the lower layer is directly returned to the flash smelting furnace, so that the copper in the slag can be recovered and the iron can be returned to the smelting process to participate in slag formation to achieve recycling. The upper layer of slag is water-quenched and sold directly as tail slag.

[0010] Furthermore, the iron-silicon ratio in the low-iron copper concentrate is 0.15~0.35, the iron content is 3%~7%, and the copper content is 40%~55%.

[0011] Furthermore, the reducing agent block is made by crushing, grinding, cold pressing, or granulating one or more of the following: waste iron filings, waste anode carbon blocks from aluminum electrolysis, waste cathode carbon blocks from aluminum electrolysis, petroleum coke, and asphalt, with a density of 3.5 g / cm³. 3 ~5.0g / cm 3 It is between slag and copper matte, and the amount added is 2% to 15% of the mass of slag.

[0012] Furthermore, the slag-forming agent is one or more of CaO, CaB2O4, Al2O3, and CaF2, and its addition amount is 1% to 10% of the mass of the smelting slag.

[0013] Furthermore, the depletion reduction time is 20 min to 60 min, and the temperature is 1200 ℃ to 1500 ℃.

[0014] Furthermore, the copper content of the tailings after water quenching does not exceed 0.30%.

[0015] Furthermore, the copper-iron alloy obtained from the depletion process is returned directly to the flash smelting furnace without cooling. The transfer equipment consists of a high-temperature slag ladle and a slag ladle car. The flash smelting furnace is equipped with a chute with a weir above the furnace body to facilitate the pouring and addition of the melt.

[0016] The significant advantages of this invention are:

[0017] This invention addresses the problem of excessively high copper content in the slag during the one-step copper smelting process of high-copper, low-iron copper concentrate. It involves adding a reducing agent to the slag for direct reduction, and adding no more than 10% of a slag-forming agent to adjust the slag properties and control the reduction depth. The resulting copper-containing molten iron is directly recycled into the smelting furnace, and the depleted slag is water-quenched and sold directly. This process offers the following advantages:

[0018] 1) Eliminating processes such as slow cooling of molten slag, crushing of cold slag, grinding, and flotation significantly shortens the process flow;

[0019] 2) Direct reduction and depletion of molten metal can reduce the copper content in the tailings to below 0.3% in one step, avoiding the difficulty of reducing the copper content in the tailings to below 0.3% through mineral processing due to the high content of difficult-to-benefit elemental copper in the slag.

[0020] 3) Adding no more than 10% of slag-forming agent will not cause a significant increase in slag volume;

[0021] 4) The copper-iron alloy product is returned to the smelting system, which not only solves the problem of the copper-iron alloy product being difficult to use, but also saves some iron-containing raw materials used for slag making. In addition, the copper-iron alloy can eliminate the iron oxide particles precipitated during the smelting process and improve the smelting indicators.

[0022] 5) Some iron elements form a loop in the entire process, realizing the self-circulation and reuse of iron in the system. This can significantly reduce the amount of iron oxide slagging agent, which reduces costs and resource waste, while also improving the copper recovery rate. It has practical application value and economic benefits. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process flow for achieving iron recycling and enhanced copper recovery in the one-step copper smelting process of low-iron copper concentrate according to the present invention.

[0024] Figure 2 This is a schematic diagram of the process of transferring copper-iron alloy to a flash melting furnace according to the present invention. Detailed Implementation

[0025] A method for achieving iron recycling and enhanced copper recovery in a one-step copper smelting process using low-iron copper concentrate includes the following steps:

[0026] a) Mix low-iron copper concentrate with an appropriate amount of iron ore powder to achieve an iron-silicon ratio of 0.4 to 0.5. At the same time, add 6% to 8% of calcium oxide by weight of the low-iron copper concentrate. Then, smelt the concentrate in a flash furnace in one step to produce smelting slag and crude copper.

[0027] b) The obtained smelting slag is fed into a reduction smelting furnace, and 2% to 15% of reducing agent blocks and 1% to 10% of slag-forming agent by mass of the smelting slag are added and mixed. After a lean reaction at 1200 ℃ to 1500 ℃ for 20 min to 60 min, the generated copper-iron alloy naturally settles and separates in the furnace. The copper-containing molten iron obtained from the lower layer is directly returned to the flash smelting furnace, so that the copper in the slag can be recovered and the iron can be returned to the smelting process to participate in slag formation to achieve recycling. The upper layer of slag is water-quenched and sold directly as tail slag, with a copper content of no more than 0.30%.

[0028] The iron-silicon ratio in the low-iron copper concentrate is 0.15-0.35, the iron content is 3%-7%, and the copper content is 40%-55%.

[0029] The reducing agent block is made by crushing, grinding, cold pressing or granulating one or more of the following: waste iron filings, waste anode carbon blocks from aluminum electrolysis, waste cathode carbon blocks from aluminum electrolysis, petroleum coke, and asphalt.

[0030] The slag-forming agent is one or more of CaO, CaB2O4, Al2O3, and CaF2.

[0031] The following are specific implementation examples based on the technical solution of this invention. The invention can be better understood through these embodiments and in conjunction with the accompanying drawings. It should be noted that this invention is not limited to the following embodiments. Any non-substantial modifications or alterations to the form or content of this invention made by those skilled in the art based on the principles of this invention are within the scope of protection of this invention.

[0032] Example 1:

[0033] The main components of a low-iron copper concentrate are: Cu 54%, S 15%, Fe 3%, SiO2 20%, with an iron-silicon ratio of 0.15. 100 tons of copper concentrate are mixed with 35 tons of iron ore powder and 6 tons of calcium oxide and smelted in a one-step flash smelting furnace. The iron-silicon ratio of the mixture is 0.4, producing 94 tons of smelting slag, which contains 15% copper. The molten slag is poured into a reduction smelting furnace, and 3.76 tons of a composite reducing agent block of "waste iron filings + aluminum electrolysis waste anode carbon powder" (with a ratio of waste iron filings to aluminum electrolysis waste anode carbon powder of 3:7) are added. The reaction is carried out at 1250℃ for 60 minutes, after which 10% (by weight) of CaO is added, allowing for natural sedimentation and separation in the furnace. The upper layer of tailings contains 0.29% copper and is poured into a slag bag as waste for sale. The lower layer of copper-containing molten iron is returned to the smelting furnace to form a loop, and the copper content of the smelting slag produced again is reduced to 8%.

[0034] Example 2:

[0035] The main components of a low-iron copper concentrate are: Cu 54%, S 15%, Fe 4%, SiO2 14%, with an iron-silicon ratio of 0.28. 120 tons of copper concentrate were mixed with 40 tons of iron ore powder and 8 tons of calcium oxide and smelted in a one-step flash smelting furnace. The iron-silicon ratio of the mixture was 0.5, producing 127 tons of smelting slag, which contained 18% copper. The molten slag was poured into a reduction smelting furnace, and 2.54 tons of a composite reducing agent block of "waste iron filings + aluminum electrolysis waste cathode carbon powder" (with a ratio of waste iron filings to electrolysis waste cathode carbon powder of 4:6) were added. The reaction was carried out at 1250℃ for 40 minutes, after which 5% (by weight of the slag) of CaB2O4 was added, and the mixture was allowed to settle and separate in the furnace. The upper slag contains 0.28% copper and is poured into a slag bag as waste for sale. The lower layer of copper-containing molten iron is returned to the smelting furnace to form a loop, and the copper content of the smelting slag produced again is reduced to 9%.

[0036] Example 3:

[0037] The main components of a low-iron copper concentrate are: Cu 60%, S 12%, Fe 7%, SiO2 20%, with an iron-silicon ratio of 0.35. 100 tons of copper concentrate are mixed with 20 tons of iron ore powder and 7 tons of calcium oxide and smelted in a one-step flash smelting furnace. The iron-silicon ratio of the mixture is 0.5, producing 95 tons of smelting slag with a copper content of 16%. The molten slag is poured into a reduction smelting furnace, and 14.25 tons of a composite reducing agent block of "scrap iron + petroleum coke" (with a ratio of scrap iron to petroleum coke of 8:2) are added. The reaction is carried out at 1350℃ for 30 minutes. Then, 3% CaO and 2% CaF2 (by weight of the slag) are added, followed by sedimentation and separation. The upper tailings slag contains 0.30% copper and is discarded and sold. The lower layer, containing copper-containing molten iron, is returned to the smelting furnace to form a loop. The copper content of the smelting slag produced again is reduced to 6%.

[0038] Example 4:

[0039] The main components of a low-iron copper concentrate are: Cu 54%, S 15%, Fe 4%, SiO2 14%, with an iron-silicon ratio of 0.29. 100 tons of copper concentrate are mixed with 35.5 tons of iron ore powder and 6.5 tons of calcium oxide and smelted in a one-step flash smelting furnace. The iron-silicon ratio of the mixture is 0.4, producing 85 tons of smelting slag, which contains 20% copper. The molten slag is poured into a reduction smelting furnace, and 12.75 tons of a composite reducing agent block of "scrap iron + petroleum coke" (with a ratio of scrap iron to petroleum coke of 7:3) are added. The mixture is reacted at 1500℃ for 20 minutes, followed by the addition of 8% CaO and 1% Al2O3 by mass of the smelting slag, and then allowed to settle and separate. The upper layer of tailings contains 0.28% copper and is poured into a slag bag as waste for sale. The lower layer of copper-containing molten iron is returned to the smelting furnace to form a loop, and the copper content of the smelting slag produced again is reduced to 8%.

[0040] Example 5:

[0041] The main components of a low-iron copper concentrate are: Cu 54%, S 15%, Fe 4%, SiO2 14%, with an iron-silicon ratio of 0.29. 100 tons of copper concentrate are mixed with 37 tons of iron ore powder and 8 tons of calcium oxide and smelted in a one-step flash smelting furnace. The iron-silicon ratio of the mixture is 0.45, producing 85 tons of smelting slag with a copper content of 16%. The molten slag is poured into a reduction smelting furnace, and 2.55 tons of a composite reducing agent block of "scrap iron + asphalt" (with a ratio of 7:3) are added. The mixture is reacted at 1300℃ for 40 minutes, followed by sedimentation and separation. The upper tailings slag contains 0.29% copper and is poured into a slag bag as a waste slag furnace. The lower layer, containing copper-containing molten iron, is returned to the smelting furnace to form a loop. The copper content of the smelting slag produced again is reduced to 8%.

[0042] Example 6:

[0043] The main components of a low-iron copper concentrate are: Cu 54%, S 15%, Fe 4%, SiO2 14%, with an iron-silicon ratio of 0.29. 100 tons of copper concentrate are mixed with 37 tons of iron ore powder and 8 tons of calcium oxide and smelted in a one-step flash smelting furnace. The iron-silicon ratio of the mixture is 0.45, producing 85 tons of smelting slag, which contains 16% copper. The molten slag is poured into an electric furnace and allowed to settle for 120 minutes. Then, the upper slag in the electric furnace is slowly cooled, crushed, and ground. Finally, the tailings after flotation contain 0.34% copper.

[0044] Table 1 Comparison of some parameters in the embodiments

[0045]

[0046] Comparing Examples 1-4, it can be seen that using different slag-forming agents can reduce the copper content in the slag to the ideal level of below 0.3%. At the same time, the addition of slag-forming agents is limited to no more than 10%, which will not cause a significant increase in the amount of slag. Furthermore, some iron elements form a loop in the entire process, which can realize the self-circulation and reuse of iron in the system, greatly reducing the amount of iron oxide slag-forming agents. This not only reduces costs and resource waste, but also improves the copper recovery rate, which has practical application value and economic benefits.

[0047] Comparing Examples 4-6, it can be seen that compared with the conventional crushing-grinding-flotation method, the method of the present invention can reduce the copper content of the smelting slag from 0.34% to below 0.3%, which has obvious advantages. In addition, the process of the present invention does not require the slag to be slowly cooled, and the cooled slag to be crushed, ground and floated again. The reducing agent can be directly added to the smelting furnace, which greatly shortens the process flow and realizes the reuse of heat lost during slow cooling to a certain extent.

[0048] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for achieving iron recycling and enhanced copper recovery in a one-step copper smelting process using low-iron copper concentrate, characterized in that: Includes the following steps: a) Mix low-iron copper concentrate with an appropriate amount of iron ore powder to achieve an iron-silicon ratio of 0.4 to 0.

5. At the same time, add 6% to 8% of calcium oxide by weight of the low-iron copper concentrate and smelt it in a flash furnace using a one-step copper smelting method to produce smelting slag and crude copper. b) The obtained smelting slag is sent to the reduction smelting furnace, and a certain amount of reducing agent block and slag-forming agent are added and mixed. After a period of depletion and reduction, the generated copper-iron alloy naturally settles and separates in the furnace. The copper-containing molten iron obtained from the lower layer is directly returned to the flash smelting furnace, so that the copper in the slag can be recovered and the iron can be returned to the smelting process to participate in slag formation to achieve recycling. The upper layer of slag is water-quenched and sold directly as tail slag. The low-iron copper concentrate has an iron-silicon ratio of 0.15 to 0.35, an iron content of 3% to 7%, and a copper content of 40% to 55%. The amount of slag-forming agent added is 1% to 10% of the mass of the smelting slag; The copper content of the tailings after water quenching does not exceed 0.30%.

2. The method for achieving iron recycling and enhanced copper recovery in a one-step copper smelting process from low-iron copper concentrate according to claim 1, characterized in that: The reducing agent block is made by crushing, grinding, cold pressing or granulating one or more of the following: waste iron filings, waste anode carbon blocks from aluminum electrolysis, waste cathode carbon blocks from aluminum electrolysis, petroleum coke, and asphalt. The amount added is 2% to 15% of the mass of the smelting slag.

3. The method for achieving iron recycling and enhanced copper recovery in a one-step copper smelting process from low-iron copper concentrate according to claim 1, characterized in that: The slag-forming agent is one or more of CaO, CaB2O4, Al2O3, and CaF2.

4. The method for achieving iron recycling and enhanced copper recovery in a one-step copper smelting process from low-iron copper concentrate according to claim 1, characterized in that: The depletion and reduction process takes 20 to 60 minutes and is carried out at a temperature of 1200 ℃ to 1500 ℃.

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