A method for reducing the Fe3O4 content in the slag of a copper or nickel flash furnace settling tank

Abstract

This invention discloses a method for reducing the Fe3O4 content in the slag of a copper or nickel flash furnace settling tank. The method includes the following steps: injecting a reactive substance through a spray gun, the reactive substance reacting with the Fe3O4 in the settling tank slag to generate FeO·SiO2 and SO2; wherein the Fe3O4 content in the settling tank slag is 20-25%; the reactive substance is copper concentrate; or nickel concentrate; or a mixture of copper concentrate and pulverized coal. This invention reduces the level of iron(III) oxide (Fe3O4) in the settling tank slag by uniformly spraying copper concentrate and pulverized coal onto the surface of the molten pool of the settling tank using interactive and reduction reactions, thereby reducing the copper content in the flash smelting slag and the copper content in the subsequent slag beneficiation tailings; uniformly spraying nickel concentrate onto the surface of the molten pool of the settling tank, again using interactive and reduction reactions to reduce the level of iron(III) oxide (Fe3O4) in the settling tank slag, thereby improving the slag depletion efficiency of nickel smelting, reducing the nickel content in the depleted waste slag, and thus improving the overall copper and nickel recovery rate in the smelting process, enhancing the economic benefits of smelting enterprises.

Description

Technical Field

[0001] This invention relates to the field of copper flash furnace refining technology, and in particular to a method for reducing the Fe3O4 content in the slag of a copper or nickel flash furnace settling tank. Background Technology

[0002] Copper is a vital material for national economic development, and its importance is increasingly prominent with the accelerating pace of industrialization. Currently, copper smelting can be divided into pyrometallurgical smelting and hydrometallurgical smelting. Pyrometallurgical copper smelting accounts for 85% of global copper production, with flash furnace smelting being one of the mainstream methods. With the development of continuous copper smelting technology, flash furnaces are evolving towards "four highs" (high feed rate, high oxygen enrichment, high matte grade, and high heat load). During this process, the amount of ferric oxide (Fe3O4) generated in the slag is relatively high. The formation of Fe3O4 encapsulates or traps valuable metals such as copper, reducing the recovery rate of slag beneficiation and overall lowering the copper smelting recovery rate. Meanwhile, the demand and production of stainless steel, a major consumer of nickel, are constantly increasing. The fuel cell, catalyst, and electroplating industries, which use nickel as a primary raw material, are developing rapidly, leading to a continuous rise in market demand for nickel. With the accelerating pace of industrialization, the importance of nickel is becoming increasingly prominent. Flash smelting technology, invented in Finland in the early 1950s, is a metallurgical technique for processing powdered sulfide ores. It boasts advantages such as high processing capacity, high automation, low environmental pollution, and low energy consumption, making it one of the mainstream nickel smelting methods. However, when flash smelting produces low-nickel matte, the highly oxidizing environment of the smelting process makes it difficult to control the content of iron tetroxide (Fe3O4) in the slag. This is especially true when using a flash furnace for one-step nickel smelting to produce high-nickel matte, resulting in a relatively high amount of Fe3O4 in the slag. The formation of Fe3O4 encapsulates or traps valuable metals such as nickel, reducing the efficiency of electric arc furnace reduction and depletion of the slag. This leads to a higher nickel content in the discarded slag, ultimately reducing the overall nickel smelting recovery rate.

[0003] Flash smelting slag contains a high amount of iron(III) oxide, which is one of the main reasons for the high copper content in the slag. The increased Fe3O4 (iron(III) oxide) content in the slag is not conducive to flash smelting slag beneficiation, increasing the cost of slag beneficiation. At the same time, the increased copper content in the slag tailings reduces the copper recovery rate.

[0004] Ferric oxide (Fe3O4) is fused into the slag, nickel matte, and the slag layer between the nickel matte and slag layers. As the amount of Fe3O4 in the melt increases, the melt viscosity increases, hindering the separation of nickel matte and slag, making it difficult to remove both. Simultaneously, the increased slag viscosity makes maintaining a thin slag layer difficult, and thermal conductivity decreases. To maintain the nickel matte temperature, the smelting temperature must be increased, which is detrimental not only to energy consumption but also to the maintenance of the flash furnace lining. Sometimes, Fe3O4 precipitates and settles at the bottom of the furnace or adheres and accumulates on the furnace wall, causing the slag melting point to rise, making smelting difficult, and reducing the effective volume of the molten pool, thus decreasing the amount of nickel matte stored in the settling tank. Flash smelting slag contains a high amount of Fe3O4, which is one of the main reasons for the high nickel content in the slag and the root cause of nodule formation in the settling tank. Meanwhile, the increased iron tetroxide content in the slag from the settling tank leads to the formation of a coating on nickel oxides in the slag, which is detrimental to subsequent flash smelting and electric arc furnace reduction of nickel slag, thus increasing smelting costs. Actual production revealed a positive correlation between the nickel content and the Fe3O4 content in the electric arc furnace slag. When the Fe3O4 content in the depleted slag is 2%, the discarded slag contains 0.2% Ni; when the Fe3O4 content is 7%, the discarded slag can reach 1.0% Ni. Therefore, reducing the nickel content in the slag requires controlling the Fe3O4 content.

[0005] Therefore, controlling the amount of ferric oxide in the sedimentation tank slag is particularly important.

[0006] Existing measures to reduce the iron tetroxide content in sedimentation tank sludge include:

[0007] (1) Coke powder added to the reaction tower: A certain proportion of coke powder is added to the reaction tower along with the raw materials in the batching system through the drying system. Due to the high ignition point of coke powder, some of it is not easily burned as fuel in the upper part of the tower. When it reaches the lower part of the tower, it reacts with oxygen at a very low partial pressure, partially generating carbon monoxide, creating a weak reducing atmosphere. This allows the generated iron(III) oxide to be reduced to ferrous oxide and slag, effectively reducing the activity of FeO and making the reduction reaction easier. At the same time, unreacted coke powder can still play a role after falling into the molten pool, reducing the iron(III) oxide in the slag and matte or nickel matte. Currently, the amount of coke powder added accounts for 0.3% to 0.5% of the furnace charge. However, because the reaction tower is a strong oxidizing atmosphere, some coke will be oxidized and lost when coke powder is added from the top of the reaction tower. At the same time, it is difficult for the coke powder to be evenly distributed when added from the reaction tower, resulting in uneven distribution in the settling tank. It is easy to accumulate in the settling tank, affecting the overall reduction effect of Fe3O4 and limiting the reduction of Fe3O4 content in the slag in the settling tank. Meanwhile, coke powder will reduce NiO to metallic nickel, increasing the proportion of metallic nickel in nickel matte and raising the melting point of nickel matte, which is not conducive to the separation of nickel matte from slag in the settling tank.

[0008] (2) Adding pig iron to the settling tank: Iron(III) oxide (Fe3O4) easily forms a bottom crust in the settling tank, which is difficult to eliminate quickly once formed. Therefore, adding pig iron can be a faster method. The pig iron reacts with the Fe3O4 in the bottom crust to generate ferrous oxide, effectively eliminating the bottom crust. From 570℃ onwards, as the temperature rises, magnetic iron oxide can be reduced to ferrous oxide by iron, which then combines with silica to form slag. Pig iron can be added to the furnace through the measuring hole, inspection hole, observation hole at the top of the reaction tower, and burner holes in the settling tank. However, while adding pig iron through these points is a manual operation, it can be used as an emergency measure to reduce the Fe3O4 content in the slag in the settling tank, but not as a long-term means of reducing the Fe3O4 content. Furthermore, excessive addition of pig iron increases the Fe content in the slag, leading to high pig iron costs.

[0009] (3) Appropriately increase the silica content: At higher temperatures, iron(III) oxide can be reduced by ferrous sulfide in the presence of SiO2, as shown in the following reaction: 3Fe3O4 + FeS + SiO2 = 5(2FeO·SiO2) + SO2. The interaction between iron(III) oxide and ferrous sulfide can occur at much lower temperatures in the presence of silica. This is essentially the formation of slag by FeO and SiO2, generating 2FeO·SiO2, which effectively reduces the reactivity of FeO. Based on this principle, increasing the silica content in the slag can promote the reduction of iron(III) oxide by ferrous sulfide. The SiO2 content in flash furnace slag is generally controlled at above 32%, and the Fe / SiO2 ratio in the slag is generally 1.15–1.25 to reduce the formation of magnetic iron oxide. However, increasing the silica content will increase the amount of slag in the settling tank, and when producing high-grade copper matte or nickel matte, the lack of FeS in the copper matte or nickel matte and slag limits the reduction of Fe3O4 content in the settling tank slag.

[0010] Patent CN102876902A discloses a method for flash-molten pool composite smelting of copper concentrate and an Outokumpu flash furnace.

[0011] A method is disclosed in this patent, in which a spray gun is fixed above a settling tank. A mixture of dry copper concentrate, quartz sand, dust, and coal is sprayed through air or oxygen-enriched air. The solid materials are mixed with high-speed oxygen-enriched air inside the spray gun and sprayed at high speed onto the surface of the melt below, forming a violently stirred zone in the melt. The stirred melt, the sprayed oxygen-enriched air, and the solid materials form a gas-slag-matte foam and emulsion. Under high temperature and a strong oxidizing atmosphere, the solid materials rapidly undergo metallurgical reactions such as thermal decomposition, oxidation, and melting, completing the slag formation and matte formation process, and generating SO2 flue gas and a small amount of soot. Due to the violent churning of the melt and the formation of gas-slag-matte foam and emulsion, the heat and mass transfer between the copper concentrate, the melt, and the oxygen-enriched air is very rapid. The melting and metallurgical reactions are completed in a very short time. The generated matte and slag melt flow towards the slag outlet on the rising flue side. After leaving the stirred melt zone, it undergoes clarification and separation at the rear of the settling tank. A high-speed spray gun installed at the outlet of the reaction tower injects oxygen-enriched air at high speed onto the surface of the melt, spraying copper concentrate, coal, and other reducing agents. This vigorous agitation of the melt allows for better heat and mass transfer of the products in the reaction tower, ensuring sufficient contact and reaction between Fe3O4 and unreacted sulfides, thus accelerating the redox process. The agitation of the melt entrains raw materials, which act as reducing agents for Fe3O4, oxidizing and melting exothermically. The injected coal serves both as fuel, supplementing the heat generated by the copper concentrate reaction, and as a reducing agent, reducing Fe3O4 and CuO, improving slag fluidity, accelerating the clarification and separation from matte, and reducing the copper content in the slag. However, this patent involves placing a top-blowing lance above the settling tank, positioned in the middle near the reaction tower. Here, the molten pool temperature is relatively low, and the pool is relatively calm, resulting in insufficient reaction kinetics and thermodynamic conditions. To significantly increase the temperature in this area, it is necessary to simultaneously inject oxygen-enriched air or air for supplemental heating and to agitate the molten pool. Otherwise, the interaction and reduction reactions will not be effective. This measure consumes a large amount of fuel, leading to high costs. Furthermore, the lance's placement in the middle of the settling tank near the reaction tower, while simultaneously agitating the melt, reduces the area originally used for slag and copper matte clarification and separation, hindering slag-matte separation. This results in higher copper content in the slag, increasing production costs. Simultaneously, the injection of oxygen-enriched air or air causes intense oxidation and combustion reactions in the vicinity of the lance. The lance's complex structure makes its lifespan uncertain, and its high cost further exacerbates the problem. Most importantly, for nickel flash furnace smelting, reducing agents such as pulverized coal cannot be injected, as this will cause nickel oxides in the slag to be reduced to metallic nickel, which will remain in the slag or enter the nickel matte. This will greatly increase the melting point of the nickel matte and slag, increase the viscosity of the slag and nickel matte, hinder the separation of slag and matte, and result in an increase in the final nickel content of the slag. Summary of the Invention

[0012] The purpose of this invention is to provide a method for reducing the Fe3O4 content in the slag of a copper or nickel flash furnace settling tank. This method involves installing a spray gun in the settling tank to uniformly spray copper concentrate and pulverized coal onto the surface of the molten pool. Through interactive and reduction reactions, the level of iron tetroxide (Fe3O4) in the slag is reduced, thereby decreasing the copper content in the flash smelting slag and subsequent slag beneficiation tailings, improving the overall copper recovery rate in the smelting process, and enhancing the economic benefits of the smelting enterprise. To achieve the above objective, this invention provides the following technical solution:

[0013] This invention provides a method for reducing the Fe3O4 content in the slag of a copper or nickel flash furnace settling tank, the method comprising the following steps:

[0014] The reactant is sprayed through a spray gun, and the reactant reacts with Fe3O4 in the sedimentation tank slag to generate FeO·SiO2 and SO2; wherein the Fe3O4 content in the sedimentation tank slag is 20-25%;

[0015] The reactant is copper concentrate; or nickel concentrate; or a mixture of copper concentrate and pulverized coal.

[0016] As a preferred embodiment, the copper concentrate contains 38-40% FeS and 8%-10% SiO2.

[0017] As a preferred embodiment, the nickel concentrate contains 38-45% FeS and 8-12% SiO2.

[0018] As a preferred embodiment, the carbon content in the pulverized coal is 45% to 55%.

[0019] As a preferred embodiment, the amount of copper concentrate injected is 10-12 t / h; the amount of nickel concentrate injected is 8-10 t / h; and the jet velocity of the injected copper concentrate or nickel concentrate is 10-15 m / s.

[0020] As a preferred embodiment, the amount of pulverized coal injected is 3-5 t / h, and the jet velocity is 10-15 m / s.

[0021] As a preferred embodiment, the spray gun is positioned 200-250 mm above the slag layer in the sedimentation tank.

[0022] As a preferred embodiment, the spray guns are installed on the end wall and the two side walls of the sedimentation tank, with a total of 3 to 6 spray guns; of which 1 to 2 are installed on the end wall and 1 to 2 are installed on each of the two side walls.

[0023] The technical effects and advantages of this invention are as follows:

[0024] (1) The spray gun of this invention is set in the sedimentation tank directly below the reaction tower, which is in the high-temperature zone of the sedimentation tank. No additional heating is required; only nitrogen is needed as the transport gas. At the same time, high-temperature copper or nickel matte and slag from the reaction tower fall into the sedimentation tank in this area, resulting in large liquid level fluctuations and good reaction kinetics. Therefore, this invention significantly reduces Fe3O4 in the slag with fewer measures.

[0025] (2) The present invention makes full use of the liquid surface fluctuation area of ​​the sedimentation tank directly below the reaction tower, without reducing the original slag and matte clarification and separation area of ​​the sedimentation tank, while reducing the Fe3O4 content in the slag, promoting the separation of slag and matte in the sedimentation tank, thereby reducing the copper or nickel content in the slag exiting the furnace more significantly.

[0026] (3) The present invention uses nitrogen as the transport gas, and nitrogen can also be used as a protective gas to protect the spray gun, so the life of the spray gun is relatively long.

[0027] (4) In this invention, the sulfiding agent or pulverized coal is directly sprayed into the settling tank, which makes the distribution more uniform and the reaction efficiency higher. This is beneficial to reducing the Fe3O4 content in the slag of the settling tank, while also reducing the metallic nickel content in the nickel matte and lowering the melting point of the nickel matte. This is beneficial to the separation of slag and matte in the settling tank and reduces the nickel content in the slag. At the same time, direct spraying into the settling tank will not affect the smelting state of the reaction tower, and the process operation is relatively simple.

[0028] (5) The present invention makes full use of the high temperature zone (1450~1500℃) of the sedimentation tank at the bottom of the reaction tower to accelerate the reaction and reduction reaction in the sedimentation tank. The Fe3O4 content of the sedimentation tank slag is reduced to a greater extent and the effect is more obvious. Moreover, there is no need to inject oxygen-enriched air and fuel to supplement the heat.

[0029] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0030] Figure 1 This is a front view of the copper flash furnace structure, an exemplary embodiment of the present invention.

[0031] Figure 2 A top view of the structure of a copper flash furnace, which is an exemplary embodiment of the present invention;

[0032] Figure 3 This is a front view of the structure of a nickel flash furnace, an exemplary embodiment of the present invention.

[0033] Figure 4 This is a top view of the structure of a nickel flash furnace, which is an exemplary embodiment of the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] The design principle of this invention is as follows:

[0036] The Fe3O4 produced in the reaction tower enters the sedimentation tank, where it undergoes an interactive reaction in the presence of FeS and SiO2:

[0037] 3Fe3O4+FeS+SiO2=5(2FeO·SiO2)+SO2;

[0038] According to the interaction reaction equation, increasing the reactivity of FeS and SiO2 can promote the reaction to proceed in the forward direction and reduce the Fe3O4 content.

[0039] When flash smelting produces lower-grade copper matte or nickel matte, the FeS content in the copper matte or nickel matte and slag is relatively high. This allows for significant cross-reactions in the settling tank, reducing the Fe3O4 content in the slag. Therefore, when smelting lower-grade copper matte or nickel matte, the amount of Fe3O4 produced in the reaction tower is small, and cross-reactions in the settling tank are also more likely to occur. Consequently, the Fe3O4 problem in the settling tank slag from flash smelting is not severe.

[0040] When flash smelting produces high-grade copper matte or nickel matte, the Fe3O4 content in the slag exiting the reaction tower is above 35%. Even when producing low-grade copper matte or nickel matte, the Fe3O4 content in the slag exiting the reaction tower is above 20%. However, the FeS content in high-grade copper matte or nickel matte is reduced, resulting in a lower degree of cross-reaction in the settling tank. Therefore, the Fe3O4 content in the flash smelting settling tank slag is still between 15% and 20%. During the formation of Fe3O4, valuable metals such as copper or nickel are encapsulated or trapped. At the same time, Fe3O4 and Cu2O easily form a eutectic phase, resulting in high slag viscosity. This affects the separation of slag from copper or nickel matte, leading to high copper or nickel content in the slag (1.8%–2.0% copper and 0.30%–0.35% nickel). This affects the subsequent slag beneficiation process, resulting in a copper content of 0.25%–0.28% in the beneficiation tailings and a low overall copper or nickel recovery rate.

[0041] This invention utilizes the heat from the high-temperature zone directly below a flash copper or nickel smelting reactor. By adding a spray gun to the settling tank to inject copper concentrate (to supplement FeS), or nickel concentrate (to supplement FeS), or copper concentrate and pulverized coal (to supplement C), the Fe3O4 content in the slag is reduced by enhancing the interaction and reduction reactions in the settling tank.

[0042] First, blown copper or nickel concentrate:

[0043] Copper or nickel concentrate contains FeS and SiO2. Increasing the reactivity of FeS and SiO2 in the slag promotes their interaction, thereby reducing the Fe3O4 content in the settling tank slag. The reaction equation is shown below:

[0044] 3Fe3O4+FeS+SiO2=5(2FeO·SiO2)+SO2;

[0045] Meanwhile, nickel oxides in the smelting slag can also react with FeS to convert nickel oxides in the slag into nickel sulfides, thereby entering the nickel matte phase and reducing the nickel content of the slag.

[0046] 9NiO+7FeS=3Ni3S2+7FeO+SO2;

[0047] Second, copper concentrate and pulverized coal are injected simultaneously:

[0048] The oxygen potential in the sedimentation tank is low, and the carbon in the injected pulverized coal will reduce Fe3O4. The presence of carbon will promote the interaction reaction. Under the dual effects of the interaction reaction and the reduction reaction, the Fe3O4 content in the sedimentation tank can be reduced even further. The following series of reactions occur in this process:

[0049] Fe3O4 + C = 3FeO + CO;

[0050] Fe3O4 + 4C = 3Fe + 4CO;

[0051] Fe3O4 + Fe = 4FeO;

[0052] 2FeO + SiO2 = 2FeO·SiO2;

[0053] Figure 1 This is a front view of the copper flash furnace structure, an exemplary embodiment of the present invention. Figure 2 A top view of the copper flash furnace structure, as shown in the exemplary embodiment of the present invention. Figure 1-2 As shown, the copper flash furnace includes a reaction tower, a settling tank, a rising flue, and a spray gun; the settling tank is equipped with the reaction tower and the rising flue, and the spray gun is located on the side wall and end wall of the settling tank directly below the reaction tower; the settling tank includes a slag layer and a copper matte layer.

[0054] Figure 3 This is a front view of the structure of a nickel flash furnace according to an exemplary embodiment of the present invention. Figure 4 This is a top view of the structure of a nickel flash furnace, an exemplary embodiment of the present invention; as shown. Figure 3-4As shown, the nickel flash furnace includes a reaction tower, a settling tank, a rising flue, a slag depletion zone, and a spray gun; the settling tank is equipped with the reaction tower and the rising flue, and the spray gun is located on the side wall and end wall of the settling tank directly below the reaction tower; multiple electrodes are provided on the slag depletion zone; the settling tank includes a slag layer and a nickel matte layer.

[0055] Furthermore, such as Figures 1-4 As shown, the sedimentation tank spray guns are installed on the end wall and the two side walls of the sedimentation tank, with a total of 3 to 6 spray guns. Among them, 1 to 2 spray guns are installed on the end wall and 1 to 2 spray guns are installed on each of the two side walls. The spray guns are installed 200 to 250 mm above the slag layer in the sedimentation tank. The reactant is delivered from the spray guns by high-pressure nitrogen gas. The reactant is copper concentrate; or nickel concentrate; or a mixture of copper concentrate and coal powder.

[0056] Based on the above-mentioned nickel flash furnace, the present invention provides a method for reducing the Fe3O4 content in the slag of the nickel flash furnace settling tank. The method includes the following steps: injecting a reactive substance from a spray gun using high-pressure nitrogen gas, wherein the reactive substance reacts with Fe3O4 in the slag of the settling tank to generate FeO·SiO2 and SO2; wherein the Fe3O4 content in the slag of the settling tank is 20-25%; and the reactive substance is copper concentrate; or nickel concentrate; or a mixture of copper concentrate and pulverized coal.

[0057] In one possible implementation, the copper concentrate contains 38-40% FeS and 8%-10% SiO2; the nickel concentrate contains 38-45% FeS and 8-12% SiO2; and the pulverized coal contains 45%-55% C.

[0058] In one possible implementation, the amount of copper concentrate injected is 10-12 t / h; the amount of nickel concentrate injected is 8-10 t / h; the jet velocity of the injected concentrate is 10-15 m / s; the amount of pulverized coal injected is 3-5 t / h; and the jet velocity of the injected copper or nickel concentrate is 10-15 m / s. The pressure of the high-pressure nitrogen gas is above 50 kPa, and the purity of the nitrogen gas is ≥99.6%, using ordinary industrial nitrogen gas.

[0059] This injection method allows copper concentrate and / or pulverized coal to be evenly distributed on the surface of the slag layer in the high-temperature zone directly below the reaction tower, promoting the interaction and reduction reactions in the slag layer area directly below the reaction tower. This effectively reduces the Fe3O4 content in the slag, decreasing it from 15-20% to 8-10%. The copper content in the flash furnace grate slag is significantly reduced, and the copper content in the tailings after slag beneficiation is reduced to 0.19%-0.22%. After the smelting slag is reduced and depleted in the electric furnace, the nickel content in the slag is reduced to 0.25%-0.26%.

[0060] Example 1: (Only copper concentrate is injected)

[0061] A domestic copper flash furnace operates at a reaction temperature of approximately 1500℃, producing 70% high-grade copper matte. The Fe3O4 content in the slag exiting the reaction tower is above 35%. Through certain interactive reactions, the Fe3O4 content in the slag in the settling tank is still around 20%. The copper content in the flash furnace slag discharge is 1.8%–2.0%, and the copper content in the tailings after slag beneficiation is 0.25%–0.28%.

[0062] Three spray guns are installed on the end wall and side wall of the settling tank directly below the reaction tower: one on the end wall and one on each of the two side walls. The spray guns are positioned 200 mm above the slag layer. High-pressure nitrogen gas is used to spray copper concentrate into the settling tank through the spray guns. The copper concentrate has an FeS content of 39.85% and a SiO2 content of 8.86%. The spray rate of copper concentrate is 10 t / h, and the spray jet velocity is 10 m / s. The copper concentrate reacts with the slag in the high-temperature zone of the settling tank directly below the reaction tower to generate FeO·SiO2 and SO2. The Fe3O4 content in the settling tank slag is reduced from 20% to 10%, and the copper content in the flash grate slag is significantly reduced. The copper content in the tailings after slag beneficiation is reduced to 0.20%–0.22%. The overall copper recovery rate of flash smelting is improved, resulting in significant economic benefits.

[0063] Example 2: (Nickel concentrate only)

[0064] In a domestic nickel flash furnace, the reaction temperature in the reaction tower is around 1500℃. It produces 30% low-grade nickel matte. The Fe3O4 content in the slag exiting the reaction tower is over 20%. Through certain interactive reactions, the Fe3O4 content in the slag in the settling tank is still 15%. After the smelting slag is sent to the electric furnace for reduction and depletion, the slag contains 0.30% nickel.

[0065] Three spray guns were installed on the end wall and side wall of the settling tank directly below the reaction tower: one on the end wall and one on each of the two side walls. The spray guns were positioned 250 mm above the slag layer. High-pressure nitrogen gas was used to spray nickel concentrate into the settling tank through the spray guns. The nickel concentrate contained 38% FeS and 11% SiO2. The spray rate was 8 t / h, and the jet velocity was 10 m / s. The nickel concentrate reacted with the slag in the high-temperature zone of the settling tank directly below the reaction tower to generate FeO·SiO2 and SO2. The Fe3O4 content in the settling tank slag decreased from 15% to 8%, and the nickel content in the slag discharged from the settling tank was significantly reduced. After the smelting slag was reduced and depleted in the electric furnace, the nickel content in the slag decreased to 0.25%. The overall nickel recovery rate of flash smelting was improved, resulting in significant economic benefits.

[0066] Example 3: (Nickel concentrate only)

[0067] In a foreign nickel flash furnace, the reaction temperature in the reaction tower is about 1450℃. It produces 70% high-nickel matte. The Fe3O4 content in the slag exiting the reaction tower is above 35%. Through certain interactive reactions, the Fe3O4 content in the slag in the settling tank is still 20%. After the smelting slag is sent to the electric furnace for reduction and depletion, the slag contains 0.35% nickel.

[0068] Three spray guns were installed on the end wall and side wall of the settling tank directly below the reaction tower, one on the end wall and one on each of the two side walls. The spray guns were positioned 200 mm above the slag layer. High-pressure nitrogen gas was used to spray nickel concentrate into the settling tank through the spray guns. The nickel concentrate had an FeS content of 40.68% and a SiO2 content of 9.78%. The spray rate of nickel concentrate was 10 t / h, and the spray jet velocity was 10 m / s. The Fe3O4 content of the slag in the settling tank decreased from 20% to 10%. The nickel concentrate and the slag in the settling tank reacted in the high-temperature zone of the settling tank directly below the reaction tower to generate FeO·SiO2 and SO2. The nickel content of the slag discharged from the settling tank was significantly reduced. After the smelting slag was reduced and depleted in the electric furnace, the nickel content of the slag was reduced to 0.26%. The overall nickel recovery rate of flash smelting was improved, and the economic benefits were obvious.

[0069] Example 4: (Simultaneous injection of copper concentrate and pulverized coal)

[0070] A domestic copper flash furnace operates at a reaction temperature of approximately 1500℃, producing 70% high-grade copper matte. The Fe3O4 content in the slag exiting the reaction tower is above 35%. Through certain interactive reactions, the Fe3O4 content in the slag in the settling tank is still around 20%. The copper content in the flash furnace slag discharge is 1.8%–2.0%, and the copper content in the tailings after slag beneficiation is 0.25%–0.28%.

[0071] Three spray guns are installed on the end wall or side wall of the settling tank directly below the reaction tower (one on the end wall and one on each side wall). The spray guns are positioned 200 mm above the slag layer. High-pressure nitrogen gas is used to spray copper concentrate and pulverized coal into the settling tank through the spray guns. The FeS content is 39.85%, the SiO2 content is 8.86%, and the C content in the pulverized coal is 50%. The spray rate of copper concentrate is 10 t / h, the spray rate of pulverized coal is 3 t / h, and the spray jet velocity is 10 m / s. The copper concentrate and the slag in the settling tank react in the high-temperature zone of the settling tank directly below the reaction tower to generate FeO·SiO2 and SO2. The Fe3O4 content in the settling tank slag is reduced from 20% to 9%, the copper content in the flash grate slag is significantly reduced, and the copper content in the tailings after slag beneficiation is reduced to 0.19%–0.21%. The overall copper recovery rate of flash smelting is improved, resulting in significant economic benefits.

[0072] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for reducing the Fe304 content in the residue of a copper or nickel flash tank, characterized in that, The method comprises the following steps: The reaction material is reacted with Fe3O4 in the precipitating pool residue to generate FeO•SiO2 and SO2 by blowing the reaction material from the lance with nitrogen gas as the conveying gas; wherein the content of Fe3O4 in the precipitating pool residue is 20-25 %; The reaction material is copper concentrate; or is nickel concentrate; or is a mixture of copper concentrate and coal powder; The lance is arranged in the precipitating pool directly below the reaction tower and is located on the end walls and the two end side walls of the precipitating pool, 200-250 mm above the residue layer of the precipitating pool.

2. The method of reducing the Fe304 content of copper or nickel flash furnace settling pond slags according to claim 1, characterized in that, The content of FeS in the copper concentrate is 38-40 %, and the content of SiO2 is 8-10 %.

3. The method of reducing the Fe304 content of the copper or nickel flash furnace settling pond sludge of claim 1, wherein, The content of FeS in the nickel concentrate is 38-45 %, and the content of SiO2 is 8-12 %.

4. The method of reducing the Fe304 content of the copper or nickel flash furnace settling pond sludge of claim 1, wherein, The content of C in the coal powder is 45-55 %.

5. The method of reducing the Fe304 content of the copper or nickel flash furnace settling pond sludge of claim 3, wherein, The amount of the sprayed copper concentrate is 10-12 t / h; the amount of the sprayed nickel concentrate is 8-10 t / h; and the jet velocity of the sprayed copper concentrate or nickel concentrate is 10-15 m / s.

6. The method of reducing the Fe304 content of the copper or nickel flash furnace settling pond sludge of claim 4, wherein, The amount of the sprayed coal powder is 3-5 t / h, and the jet velocity of the sprayed coal powder is 10-15 m / s.

7. The method of reducing the Fe304 content of the copper or nickel flash furnace settling pond sludge of claim 1, wherein, The lance is 3-6 lances in total; wherein there are 1-2 lances on the end walls, and there are 1-2 lances on each of the two end side walls.

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