Method for preparing reduced iron powder from hydrometallurgy hematite slag

Abstract

The invention relates to a method for preparing reduced iron powder from hydrometallurgy hematite slag, and belongs to the technical field of chemical metallurgy. The method comprises the following steps: crushing the hydrometallurgy hematite slag, uniformly mixing the crushed hydrometallurgy hematite slag with a carbonaceous reducing agent and an activating agent, and carrying out deoxidation and impurity removal reaction under the conditions that the temperature is 800-1300 DEG C, the mass ratio of carbon to iron is 0.6-1.2 and the reaction time is 1-4 hours. And finely grinding an impurity-removed product, then carrying out magnetic separation, carrying out deep impurity removal on the obtained magnetic product at 700-1050 DEG C by adopting hydrogen, and after the reaction is finished, carrying out rapid cooling by adopting nitrogen protection to obtain the reduced iron powder. According to the method, impurity components in the hydrometallurgy hematite slag can be effectively removed, and the produced reduced iron powder is high in quality, fine in granularity, narrow in distribution and good in reaction activity.

Description

Technical Field

[0001] The invention relates to a method for preparing reduced iron powder from hydrometallurgical hematite slag, belonging to the technical field of material chemical industry. Background Art

[0002] Hematite iron removal from hydrometallurgical solutions such as zinc and nickel is an advanced technology for hydrometallurgical iron removal. Its principle is to oxidize, hydrolyze, crystallize and precipitate ferrous ions in zinc sulfate and nickel sulfate solutions containing ferrous sulfate under high temperature and high pressure conditions to obtain Fe2O3. The iron removal product produced by this hematite iron removal method is called hematite slag. Since the oxidative hydrolysis, crystallization and precipitation of ferrous ions are affected by the coexistence of zinc sulfate, nickel sulfate and other sulfates in the solution, the hematite slag produced contains certain impurity components in addition to ferric oxide. The typical hematite slag composition is Fe2O3 70%~90%, ZnSO4 1%~6%, NiSO4 0.2~2.5%, CaSO4 0.5%~5%, S 3%~8%, Mn0.2%~1%, P≤0.5%, and the rest is mainly crystal water.

[0003] At present, high-quality hematite slag can be used as raw materials for cement, ceramics, and iron smelting. However, since the hematite slag produced by industrial production contains more impurities and has a low iron content, it is difficult to use the hematite slag at a high value. Therefore, how to efficiently remove the impurities in the hematite slag, how to improve the iron grade in the hematite slag, and how to prepare the hematite slag into a higher-value product to realize the utilization of iron resources are common technical problems faced by the hydrometallurgical industry. In the prior art, patent application CN109607622A introduces a method for preparing iron red products by removing iron slag from hematite ore by hydrometallurgical zinc smelting; the method comprises the following steps:

[0004] Step 1, washing the iron removal slag of the wet zinc smelting hematite process with deionized water to remove soluble sulfate and other salt substances in the iron removal slag of the wet zinc smelting hematite process;

[0005] Step 2, placing the iron removal slag of the wet zinc smelting hematite method after washing in step 1 in a sulfuric acid solution, and performing high-temperature hydrothermal impurity removal in an acidic solution to remove impurities such as jarosite, sodium iron vanadium, and basic sulfates of zinc and iron, and at the same time, converting the iron ions decomposed from the iron vanadium into ferric oxide under a high temperature and high pressure environment;

[0006] Step 3: subject the iron removal slag of the wet zinc smelting hematite method after the acid solution high temperature hydrothermal removal in step 2 to neutral solution high temperature hydrothermal removal to obtain an iron red product. This technology uses high temperature and high pressure acid leaching to remove impurities and neutral high temperature hydrothermal removal to obtain an iron red product with a ferric oxide content of 95.8-96.7wt% and Fe67.3-68.1wt%.

[0007] Because among the currently disclosed technologies, the methods for removing impurities from hematite generally include: flotation (including direct and reverse flotation), magnetic separation, gravity separation, roasting and beneficiation, and the technology introduced in CN109607622A; but the existing technologies involved are either extremely costly or have a lot of room for improvement in impurity removal effects, and there are few records in the existing technologies of using hydrometallurgical hematite slag as raw material to prepare reduced iron powder with high iron content and narrow particle size distribution.

[0008] The hematite slag produced by the hydrometallurgical iron removal process of non-ferrous metals such as zinc and nickel to be treated by the present invention contains various impurities such as zinc sulfate, nickel sulfate, calcium sulfate, manganese sulfate, sulfate ions combined with oxygen in ferric oxide, crystal water, etc., and the impurity components exist in the hematite slag in various forms such as inclusion, encapsulation, complexation, adsorption, etc. It is difficult to remove these impurity components with low cost and high efficiency and prepare reduced iron powder with a narrow particle size distribution by using the existing flotation method, magnetic separation method, gravity separation method, roasting beneficiation method and the method disclosed in CN109607622A, resulting in difficulty in high-value utilization of the hematite slag produced by the hydrometallurgical iron removal. Summary of the invention

[0009] Aiming at the shortcomings of hydrometallurgical hematite slag, such as many impurity components, complex occurrence forms of impurity components, difficulty in effective impurity removal by existing methods, and difficulty in high-value utilization of hematite slag, the present invention, based on the existing technology, further studies and overcomes key technologies, obtains a scheme for preparing reduced iron powder with thorough separation of impurity components, high iron content, and good product quality, and based on this, forms the present invention. The present invention provides a method for preparing reduced iron powder from hydrometallurgical hematite slag, which comprises: crushing the hydrometallurgical hematite slag and mixing it evenly with a carbonaceous reducing agent and an activator, performing a deoxidation and impurity removal reaction at high temperature, and efficiently separating zinc, sulfur, oxygen and other components in the hematite slag. The impurity removal product is finely ground and then subjected to magnetic separation to remove impurities such as calcium oxide, carbon, manganese, and phosphorus; the obtained magnetic product is subjected to deep impurity removal at high temperature using hydrogen to remove impurities such as zinc, sulfur, oxygen, and carbon involved, and nitrogen protection is used to quickly cool the reaction after the reaction is completed to obtain reduced iron powder.

[0010] The present invention provides a method for preparing reduced iron powder from hydrometallurgical hematite slag, and the specific operation process includes: crushing the hydrometallurgical hematite slag and mixing it evenly with a carbonaceous reducing agent and an activator, and then performing a deoxidation and impurity removal reaction at high temperature. The impurity removal product is finely ground and then magnetically separated, and the obtained magnetic product is deeply impurized by hydrogen at high temperature. After the reaction is completed, nitrogen protection is used to quickly cool down to obtain reduced iron powder. The specific steps are as follows:

[0011] (1) High-temperature deoxidation and impurity removal: The crushed hematite slag is mixed evenly with a carbonaceous reducing agent and an activator, and high-temperature deoxidation and impurity removal is carried out under the conditions of 800-1300°C, a carbon / iron mass ratio of 0.6-1.2, and a reaction time of 30 min-210 min; the activator is calcium oxide and / or strong calcium oxide, and the amount of the activator added is 1-5% of the weight of the hematite slag;

[0012] (2) Fine grinding and magnetic separation: The impurity-removed product produced in step (1) is finely ground to a particle size of ≤74 μm, and then subjected to magnetic separation to obtain a magnetic product.

[0013] (3) Deep impurity removal: The magnetic product of step (2) is subjected to deep impurity removal at 700-1050°C by using hydrogen. After the reaction is completed, nitrogen is used for rapid cooling to obtain reduced iron powder. The cooling rate of rapid cooling is 5-10°C / min.

[0014] Optimized, the hydrometallurgical hematite slag includes hematite slag produced by removing iron from non-ferrous metal hydrometallurgical solutions such as zinc and nickel using the hematite method. Its main chemical components include by mass percentage: Fe2O3 70%~90%, ZnSO4 1%~6%, NiSO4 0.2~2.5%, CaSO4 0.5%~5%, S 3%~8%. Further preferably, the hydrometallurgical hematite slag is mainly composed of: Fe2O3 70%~90%, ZnSO4 1%~6%, NiSO4 0.2~2.5%, CaSO4 0.5%~5%, S 3%~8%, Mn0.2%~1%, P≤0.5%, and the rest is mainly crystal water.

[0015] The particle size of the hydrometallurgical hematite slag is less than or equal to 74 microns.

[0016] Optimally, the carbonaceous reducing agent used in the high-temperature deoxidation and impurity removal in step (1) is one or more of coke powder, anthracite, and reduced coal, and the activator is quicklime or limestone powder. The amount of the activator added is 1% to 5% by weight of the hematite slag, preferably 2% to 3%.

[0017] The temperature of the high-temperature deoxidation and impurity removal in step (1) of the present invention is controlled to be 800-1300°C, preferably 900-1150°C, and more preferably 1000-1100°C, because under such conditions, the removal efficiency of impurity components such as zinc, sulfur, and oxygen is high, the energy consumption is low, and the operating cost is relatively suitable; although too high a temperature can improve the removal efficiency of impurity components, it will lead to increased energy consumption and higher operating costs. Too low a temperature will lead to a poor removal effect of impurity components, or even no removal of impurity components, resulting in poor quality of reduced iron powder.

[0018] Optimally, the magnetic field strength of the magnetic separation process in step (2) is 500-1200 Gs.

[0019] Optimally, the reaction time of deep impurity removal in step (3) is 1 to 4 hours.

[0020] The temperature of deep impurity removal in step (3) of the present invention is controlled to be 700-1100°C, preferably 850-1000°C because under this temperature condition, the removal efficiency of impurity components such as zinc, oxygen, and carbon is high, the iron powder does not stick together, the dispersibility is good, the energy consumption is low, and the operating cost is relatively suitable; too high a temperature will cause the iron powder to stick together, the dispersibility will deteriorate, and the energy consumption and operating cost will increase. Too low a temperature will lead to poor removal efficiency of impurity components and poor quality of reduced iron powder.

[0021] Control the relative amount of hydrogen to 50~150Nm 3 / t-iron powder, because the impurity removal efficiency is high under this dosage condition, and the operating cost is relatively appropriate. Too little hydrogen dosage will lead to low impurity removal efficiency and poor quality of reduced iron powder; the hydrogen flow rate is controlled to be 0.2-1.0m / min, because the impurity removal efficiency is high and the hydrogen utilization efficiency is high under this flow rate condition. Too low flow rate will lead to low impurity removal efficiency, and too fast flow rate will lead to low hydrogen utilization. At the same time, at this flow rate, the temperature of deep impurity removal can make the particle size range of the product distribution narrower.

[0022] Furthermore, the chemical composition of the reduced iron powder produced by the present invention is: MFe≥90%, Zn≤0.3%, Ni≤0.6%, S≤0.5%, CaO≤0.5%, Mn≤0.2%, Cr≤0.1%, P≤0.0.03%, and the rest are mainly oxygen and carbon.

[0023] The particle size distribution range of the reduced iron powder obtained by the present invention is narrow. 90 Can be controlled at 58 microns and below.

[0024] The beneficial effects of the present invention are:

[0025] (1) The present invention can effectively remove various impurity components in hydrometallurgical hematite slag. By adopting various process steps and reaction principles, zinc sulfate, calcium sulfate, manganese sulfate and other impurity components in the hematite slag can be deeply removed step by step. The reduced iron powder produced has a high iron content and a low impurity content, and the reduced iron powder has high quality.

[0026] (2) The present invention realizes the high-value utilization of hydrometallurgical hematite slag, and prepares hematite slag with low iron content and high impurity content, which is difficult to utilize as a resource, into high-value reduced iron powder, thereby improving the utilization value of hydrometallurgical hematite slag.

[0027] (3) The present invention can be connected with the hydrometallurgical hematite iron removal process, and the reduced iron powder produced has fine particle size, narrow distribution, high reaction activity, and good quality, which can realize the high-value utilization of hydrometallurgical associated iron. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a SEM image of the reduced iron powder obtained in Example 3;

[0029] Figure 2 This is the particle size distribution diagram of the reduced iron powder obtained in Example 3.

[0030] from Figure 1 It can be seen that the reduced iron obtained by the present invention has a larger specific surface area and a maximum particle size of less than 75 microns.

[0031] from Figure 2 It can be seen that the particle size distribution of the product obtained in Example 3 of the present invention is relatively narrow. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with specific implementation modes.

[0033] Example 1

[0034] A method for preparing reduced iron powder from hydrometallurgical hematite slag, the specific operation process of which includes: crushing the hematite slag produced by zinc hydrometallurgical iron removal and mixing it evenly with a carbonaceous reducing agent and an activator, and then performing a deoxidation and impurity removal reaction at high temperature. The impurity removal product is finely ground and magnetically separated, and the obtained magnetic product is deeply impurized at high temperature using hydrogen. After the reaction is completed, nitrogen protection is used to quickly cool down to obtain reduced iron powder. The specific operation is as follows: 2.0 kg of hematite slag produced by zinc hydrometallurgical iron removal is taken, and its chemical composition is Fe2O3 80%, ZnSO4 2.6%, NiSO4 0.2%, CaSO4 1.8%, S 3.5%, Mn0.20%, P0.1%, and the rest is mainly crystal water. After the hematite slag is crushed to a particle size of ≤74 microns, it is fully mixed with 1120g of coke powder (carbon / iron mass ratio is 1.0) and 100g of quicklime (activator addition amount is 5%), and the mixture is heated to 1000℃ and the reaction time is 3h for high-temperature deoxidation and impurity removal. After the impurity removal product is cooled to room temperature, it is finely ground to a particle size of ≤74 microns, and then wet magnetic separation is carried out under the condition of a magnetic field strength of 800 Gs to obtain 1062g of magnetic product. Under the action of hydrogen, the magnetic product is heated to 950℃, the reaction time is 2h, the hydrogen flow rate is 0.5m / min, and the hydrogen dosage is 90Nm 3 / t-iron powder, after the reaction, nitrogen protection was used for rapid cooling, and the cooling rate of rapid cooling was 8°C / min, to obtain 1035g of reduced iron powder. The chemical composition of the reduced iron powder is: MFe 95.7wt%, Zn 0.21wt%, Ni 0.05wt%, S 0.35wt%, CaO 0.38%, Mn0.05wt%, Cr 0.03wt%, P 0.001wt%, and the balance is oxygen and carbon.

[0035] The recovery rate of iron was 93.8%;

[0036] The D of the reduced iron powder obtained 30 10.5 microns, D 50 27.3 microns, D 75 43.6 μm D 90 It is 52.5 microns.

[0037] Example 2

[0038] A method for preparing reduced iron powder from hematite slag by hydrometallurgy, the specific operation process of which includes: crushing the hematite slag produced by zinc hydrometallurgy to remove iron, mixing it evenly with a carbonaceous reducing agent and an activator, and then performing a deoxidation and impurity removal reaction at high temperature. The impurity removal product is finely ground and magnetically separated, and the obtained magnetic product is deeply impurized by hydrogen at high temperature. After the reaction is completed, nitrogen protection is used to quickly cool down to obtain reduced iron powder. The specific operation is as follows: 2.0 kg of hematite slag produced by zinc hydrometallurgy to remove iron is taken, and its chemical composition is Fe2O3 74.2%, ZnSO4 3.7%, NiSO4 0.3%, CaSO4 2.5%, S 4.8%, Mn0.21%, P 0.10%, and the rest is mainly crystal water. After the hematite slag is crushed to a particle size of ≤74 microns, it is fully mixed with 890.4g of coke powder (carbon / iron mass ratio is 0.6) and 200g of quicklime (activator addition amount is 10%), and the mixture is heated to 1100℃ and the reaction time is 4h for high-temperature deoxidation and impurity removal. After the impurity removal product is cooled to room temperature, it is finely ground to a particle size of ≤74 microns, and then wet magnetic separation is carried out under the condition of a magnetic field strength of 600Gs to obtain 1155g of magnetic product. Under the action of hydrogen, the magnetic product is heated to 900℃, the reaction time is 3h, the hydrogen flow rate is 0.8m / min, and the hydrogen dosage is 150Nm 3 / t-iron powder, after the reaction, nitrogen protection was used for rapid cooling, and the cooling rate of rapid cooling was 6°C / min, to obtain 1035g of reduced iron powder. The chemical composition of the reduced iron powder is: MFe 96.4wt%, Zn 0.10wt%, Ni 0.04wt%, S 0.31wt%, CaO 0.32%, Mn 0.03wt%, Cr 0.01wt%, P 0.001wt%, and the balance is oxygen and carbon.

[0039] The recovery rate of iron was 92.5%;

[0040] The D of the reduced iron powder obtained 30 9.5 microns, D 50 25.2 microns, D 75 47.3 μm D 90 It is 55.7 microns.

[0041] Example 3

[0042] A method for preparing reduced iron powder from hydrometallurgical hematite slag, the specific operation process of which includes: crushing the hematite slag produced by zinc hydrometallurgy to remove iron, mixing it with a carbonaceous reducing agent and an activator, and then performing a deoxidation and impurity removal reaction at high temperature. The impurity removal product is finely ground and then magnetically separated, and the obtained magnetic product is deeply impurized at high temperature using hydrogen. After the reaction is completed, nitrogen protection is used to quickly cool down to obtain reduced iron powder. The specific operation is as follows: 2.0 kg of hematite slag produced by zinc hydrometallurgy to remove iron is taken, and its chemical composition is Fe2O3 85.7%, ZnSO4 2.1%, NiSO4 0.2%, CaSO4 1.2%, S 3.0%, Mn0.15%, P 0.06%, and the rest is mainly crystal water. After the hematite slag is crushed to a particle size of ≤74 microns, it is fully mixed with 1129g of anthracite (carbon / iron mass ratio of 0.8) and 50g of quicklime (activator addition amount of 2.5%), and the mixture is heated to 1050℃ and the reaction time is 3.5h for high-temperature deoxidation and impurity removal. After the impurity removal product is cooled to room temperature, it is finely ground to a particle size of ≤74 microns, and then wet magnetic separation is carried out under a magnetic field strength of 1100 Gs to obtain 1261g of magnetic product. Under the action of hydrogen, the magnetic product is heated to 950℃, the reaction time is 4h, the hydrogen flow rate is 1 m / min, and the hydrogen dosage is 100Nm 3 / t-iron powder, after the reaction, nitrogen protection was used for rapid cooling, and the cooling rate of rapid cooling was 4°C / min, to obtain 1215g of reduced iron powder. The chemical composition of the reduced iron powder is: MFe 95.5wt%, Zn 0.11wt%, Ni 0.06wt%, S 0.33wt%, CaO 0.33%, Mn 0.02wt%, Cr 0.01wt%, P 0.001wt%, and the balance is oxygen and carbon.

[0043] The recovery rate of iron was 96.7%;

[0044] The D of the reduced iron powder obtained 30 15.93 microns, D 50 25.47 microns, D 75 37.96 microns, D 90is 49.00 microns.

[0045] Example 4

[0046] A method for preparing reduced iron powder from hydrometallurgical hematite slag, the specific operation process of which includes: crushing the hematite slag produced by nickel hydrometallurgical iron removal, mixing it evenly with a carbonaceous reducing agent and an activator, and then performing a deoxidation and impurity removal reaction at high temperature. The impurity removal product is finely ground and magnetically separated, and the obtained magnetic product is deeply impurized at high temperature using hydrogen. After the reaction is completed, nitrogen protection is used to quickly cool down to obtain reduced iron powder. The specific operation is as follows: 2.0 kg of hematite slag produced by nickel hydrometallurgical iron removal is taken, and its chemical composition is Fe2O3 90%, ZnSO4 0.2%, NiSO4 1.8%, CaSO4 1.1%, S 2.6%, Mn0.12%, P 0.04%, and the rest is mainly crystal water. After the hematite slag is crushed to a particle size of ≤74 microns, it is fully mixed with 1075g of reducing coal (carbon / iron mass ratio of 0.7) and 150g of limestone powder (activator addition amount of 10%), and the mixture is heated to 800℃ and the reaction time is 4h for high-temperature deoxidation and impurity removal. After the impurity removal product is cooled to room temperature, it is finely ground to a particle size of ≤74 microns, and then wet magnetic separation is carried out under a magnetic field strength of 500 Gs to obtain 1245g of magnetic product. Under the action of hydrogen, the magnetic product is heated to 1000℃, the reaction time is 4h, the hydrogen flow rate is 0.2 m / min, and the hydrogen dosage is 50Nm 3 / t-iron powder, after the reaction, nitrogen protection was used for rapid cooling, and the cooling rate of rapid cooling was 4°C / min, to obtain 1241g of reduced iron powder. The chemical composition of the reduced iron powder is: MFe 94.2wt%, Zn 0.1wt%, Ni 0.6wt%, S 0.35wt%, CaO0.32%, Mn 0.01wt%, Cr 0.01wt%, P 0.001wt%, and the balance is oxygen and carbon.

[0047] The recovery rate of iron was 92.8%;

[0048] The D of the reduced iron powder obtained 30 12.2 microns, D 50 27.1 microns, D 75 43.2 μm D 90 It is 56.7 microns.

[0049] Example 5

[0050] The other conditions are the same as those in Example 1, except that the reaction temperature for high-temperature deoxidation and impurity removal of hematite slag, coke powder and quicklime is 1300° C. The chemical composition of the reduced iron powder obtained under these conditions is: MFe 97.2wt%, Zn 0.12wt%, Ni 0.03wt%, S 0.32wt%, CaO 0.30%, Mn 0.04wt%, Cr 0.02wt%, P 0.001wt%, and the balance is oxygen and carbon.

[0051] The recovery rate of iron was 94.6%;

[0052] The D of the reduced iron powder obtained 30 9.7 microns, D 50 24.6 microns, D 75 36.1 μm D 90 It is 49.5 microns.

[0053] Example 6

[0054] The other conditions are the same as those in Example 1, except that the reaction temperature for high-temperature deoxidation and impurity removal of hematite slag, coke powder and quicklime is 800° C. The chemical composition of the reduced iron powder obtained under these conditions is: MFe 90.1wt%, Zn 0.87wt%, Ni 0.03wt%, S 0.95wt%, CaO 0.76%, Mn 0.15wt%, Cr 0.04wt%, P 0.002wt%, and the balance is oxygen and carbon.

[0055] The recovery rate of iron is 90.2%; compared with Example 1, the recovery rate of iron is significantly reduced and the iron content in the product is also significantly lower.

[0056] The D of the reduced iron powder obtained 30 12.1 microns, D 50 25.6 microns, D 75 39.2 μm D 90 It is 51.4 microns.

[0057] Comparative Example 1

[0058] The other conditions are the same as those in Example 1, except that the reaction temperature for high-temperature deoxidation and impurity removal of hematite slag, coke powder and quicklime is 700° C. The chemical composition of the reduced iron powder obtained under these conditions is: MFe 76.5wt%, Zn 1.58wt%, Ni 0.03wt%, S 2.13wt%, CaO 1.06%, Mn 0.21wt%, Cr 0.05wt%, P 0.003wt%, and the balance is oxygen and carbon.

[0059] The recovery rate of iron was 83.1%;

[0060] The D of the reduced iron powder obtained 30 14.2 microns, D 50 28.1 microns, D 75 42.4 μm D 90 It is 55.3 microns.

[0061] Comparative Example 2

[0062] Other conditions are the same as those in Example 1, except that:

[0063] After the first magnetic separation, the carbon / iron mass ratio is 1.0, the coke powder and magnetic product are mixed evenly, and the reaction time is 2h at 950℃; after the reaction, the furnace is cooled to room temperature (cooling rate is 1℃ / min), and then magnetic separation is performed again (the magnetic separation conditions are the same as the first magnetic separation), and 1045g of reduced iron is obtained. The chemical composition of the reduced iron is: MFe 92.5wt%, Zn 0.18wt%, Ni 0.03wt%, S 0.35wt%, CaO 0.35%, Mn 0.05wt%, Cr0.03wt%, P 0.001wt%, and the balance is oxygen and carbon.

[0064] At this time, most of the reduced iron obtained is in block form, with excess carbon wrapped in the middle.

[0065] Comparative Example 3

[0066] Other conditions are the same as those in Example 1, except that:

[0067] The magnetic product was heated to 950°C under the action of hydrogen, the reaction time was 2h, the flow rate of hydrogen was 0.1m / min, the amount of hydrogen was 18Nm 3 / t-iron powder, after the reaction, nitrogen protection was used for rapid cooling, and the cooling rate of rapid cooling was 3°C / min, to obtain 1041g of reduced iron powder. The chemical composition of the reduced iron is: MFe 93.6wt%, Zn 0.22wt%, Ni0.03wt%, S 0.35wt%, CaO0.31%, Mn 0.04wt%, Cr0.03wt%, P 0.001wt%, and the balance is oxygen and carbon.

[0068] The recovery rate of iron was 95.1%;

[0069] The D of the reduced iron powder obtained 30 40.6 microns, D 50 75.2 microns, D 75 98.5 μm D 90 The micrometer is 120 microns.

[0070] Comparative Example 4

[0071] Other conditions are the same as those in Example 1, except that:

[0072] The magnetic product was heated to 1150°C under the action of hydrogen, the reaction time was 2h, the hydrogen flow rate was 0.2m / min, the hydrogen dosage was 36Nm 3 / t-iron powder, after the reaction, nitrogen protection was used for rapid cooling, and the cooling rate of rapid cooling was 2°C / min, to obtain 1032g of reduced iron powder. The chemical composition of the reduced iron is: MFe 97.3wt%, Zn 0.12wt%, Ni 0.03wt%, S 0.30wt%, CaO 0.25%, Mn 0.05wt%, Cr0.02wt%, P 0.001wt%, and the balance is oxygen and carbon.

[0073] The recovery rate of iron was 96.2%;

[0074] The D of the reduced iron powder obtained 30 62 microns, D 50 135 microns, D 75 180 μm D 90 It is 220 microns.

[0075] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for preparing reduced iron powder from hydrometallurgical hematite slag, characterized in that The steps include: (1) High-temperature deoxidation and impurity removal: The crushed hematite slag is mixed evenly with a carbonaceous reducing agent and an activator, and high-temperature deoxidation and impurity removal is carried out under the conditions of 800-1300°C, a carbon / iron mass ratio of 0.6-1.2, and a reaction time of 1-4 hours; the activator is calcium oxide and / or strong calcium oxide, and the amount of the activator added is 1-12% of the weight of the hematite slag; (2) Fine grinding and magnetic separation: The impurity-removed product produced in step (1) is finely ground to a particle size of ≤74 μm, and then subjected to magnetic separation to obtain a magnetic product; (3) Deep impurity removal: The magnetic product of step (2) is subjected to deep impurity removal at 700-1050°C by using hydrogen. After the reaction is completed, nitrogen protection is used for rapid cooling to obtain reduced iron powder. The cooling rate of the rapid cooling is 5-10°C / min.

2. The method for preparing reduced iron powder from hydrometallurgical hematite slag according to claim 1, characterized in that: The hydrometallurgical hematite slag comprises, by mass percentage, 70% to 90% Fe2O3, 1% to 6% ZnSO4, 0.2 to 2.5% NiSO4, 0.5% to 5% CaSO4, and 3% to 8% S.

3. The method for preparing reduced iron powder from hydrometallurgical hematite slag according to claim 1, characterized in that: The particle size of the hematite slag is less than or equal to 74 microns.

4. The method for preparing reduced iron powder from hydrometallurgical hematite slag according to claim 1, characterized in that: The carbonaceous reducing agent used in the high-temperature deoxidation and impurity removal in step (1) is one or more of coke powder, anthracite, and reduced coal, and the activator is quicklime or limestone powder. The amount of the activator added is 1% to 10% of the weight of the hematite slag, preferably 2% to 10%.

5. The method for preparing reduced iron powder from hydrometallurgical hematite slag according to claim 1, characterized in that: The temperature of the high-temperature deoxidation and impurity removal in step (1) is controlled to be 800-1300°C, preferably 900-1150°C, and more preferably 1000-1100°C.

6. The method for preparing reduced iron powder from hydrometallurgical hematite slag according to claim 1, characterized in that: The magnetic field intensity of the magnetic separation process in step (2) is 500-1200 Gs.

7. The method for preparing reduced iron powder from hydrometallurgical hematite slag according to claim 1, characterized in that: The reaction time of the deep impurity removal in step (3) is 1 to 4 hours.

8. The method for preparing reduced iron powder from hydrometallurgical hematite slag according to claim 1, characterized in that: The temperature of deep impurity removal in step (3) is controlled to be 700-1100°C, preferably 850-1000°C.

9. The method for preparing reduced iron powder from hydrometallurgical hematite slag according to claim 1, characterized in that: In step (3), the relative amount of hydrogen is controlled to be 50~150Nm 3 / t-iron powder, control the flow rate of hydrogen to 0.2-1.0m / min.

10. The method for preparing reduced iron powder from hydrometallurgical hematite slag according to claim 1, characterized in that: The chemical composition of the reduced iron powder produced by the present invention includes, by mass percentage, MFe≥90%, Zn≤0.3%, Ni≤0.6%, S≤0.5%, CaO≤0.5%, Mn≤0.2%, Cr≤0.1%, and P≤0.0.03%; The D of the reduced iron powder obtained 90 At 58 microns and below.

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