Process for nickel extraction from a high acid, atmospheric, leaching medium

Abstract

The present application relates to a kind of high acid, atmospheric, circulating leaching process of nickel, comprising the following steps: (1) nickel is ground and treated, and fine grinding nickel is obtained;(2) fine grinding nickel is leached by concentrated sulfuric acid, and respectively obtain hydrogen sulfide gas and leaching slurry;(3) leaching slurry is filtered and separated by leaching filter press, and respectively obtain filter residue and leaching liquid after filter press;Leaching liquid after filter press is treated by evaporation concentrator, and respectively obtain condensed water A and concentrated mother liquor;(4) filter residue enters slurry dissolving tank and is dissolved, and slurry filter press is filtered, and respectively obtain filter copper residue and iron, nickel, cobalt containing sulfate dissolved solution;(5) iron, nickel, cobalt containing sulfate dissolved solution is reacted with medium pressure steam and oxygen to remove iron, and obtain iron-removed slurry;(6) iron-removed slurry is separated by sedimentation, washed and evaporated, and respectively obtain hematite tailings, nickel sulfate crystal and high acid mother liquor.The present application has low cost, short process, and can realize the separation of main metal nickel and impurity metal copper and iron.

Description

Technical Field

[0001] This invention relates to the non-ferrous metal hydrometallurgical industry, belonging to the field of metallurgical process technology and equipment, and particularly to a high-acid, atmospheric-pressure, cyclic leaching process for nickel matte. Background Technology

[0002] A non-ferrous metallurgical enterprise uses a side-blown furnace to process high-magnesium, low-nickel concentrate and various difficult-to-process nickel raw materials such as return slag. The materials undergo strong oxidation smelting in the side-blown smelting zone, and the smelting product is medium-grade nickel matte (the chemical composition of medium-grade nickel matte is: Ni-32%, Cu-24%, Fe-14%, Co-1.1%, S-26%). To increase the nickel content and reduce the iron content in medium-grade nickel matte, it is generally necessary to send the medium-grade nickel matte to a converter for blowing to produce high-grade nickel matte. However, this reaction process results in a large loss rate of cobalt, with approximately 40% of the cobalt being blown into the slag, significantly reducing the cobalt yield.

[0003] To improve the cobalt yield, it is urgent to develop a process for treating nickel matte directly using hydrometallurgical techniques without refining. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a short-process, low-cost, high-acid, atmospheric-pressure, cyclic leaching process for nickel matte.

[0005] To address the aforementioned problems, the present invention provides a high-acid, atmospheric-pressure, cyclic leaching process for nickel matte, comprising the following steps:

[0006] (1) Medium-grade nickel matte is fed into a dry ball mill for grinding to obtain finely ground medium-grade nickel matte with a particle size of -280 mesh and greater than 95%;

[0007] (2) The finely ground medium-grade nickel matte is conveyed by a screw conveyor into the first stage of the multi-stage atmospheric pressure leaching tank. At the same time, concentrated sulfuric acid is added to the first stage atmospheric pressure leaching tank for leaching, and the sulfuric acid concentration in each stage of the atmospheric pressure leaching tank is controlled to be ≥6mol / L. After leaching, hydrogen sulfide gas and leaching slurry are obtained respectively. The hydrogen sulfide gas is collected and sulfur is prepared by the Claus process or directly absorbed by liquid alkali.

[0008] (3) The leaching slurry is filtered and separated by a leaching filter press to obtain filter residue and leaching filtrate; the leaching filtrate is treated by an evaporator to obtain condensate A and concentrated mother liquor; the concentrated mother liquor is returned to the multi-stage atmospheric pressure leaching tank for circulating leaching; the condensate A enters the slurry dissolving tank.

[0009] (4) The filter press residue enters the slurry dissolution tank, where it is slurry dissolved using fresh water and washing liquid. After filtration in the slurry filter press, copper filter residue and sulfate solution containing iron, nickel, and cobalt are obtained respectively. The copper filter residue is then sent to a copper industry company for processing.

[0010] (5) The sulfate solution containing iron, nickel and cobalt is fed into a pressurized iron removal reactor, while medium-pressure steam and oxygen are simultaneously supplied to carry out the iron removal reaction, and iron-removed slurry is obtained.

[0011] (6) The iron-removed slurry enters a pressure thickener for sedimentation and separation, yielding underflow A and overflow A respectively;

[0012] The underflow A enters a three-stage CCD washing and thickening machine for processing, yielding underflow B and overflow B respectively; the overflow B is returned to the slurry dissolving tank; the underflow B enters a washing filter press, yielding CCD washing filtrate and hematite tailings respectively; the CCD washing filtrate is returned to the slurry dissolving tank; the hematite slag is packaged and sold externally.

[0013] The overflow liquid A is processed by an evaporator crystallizer to obtain condensate B, nickel sulfate crystals, and high-acid mother liquor; condensate B is returned to the three-stage CCD washing thickener; and the high-acid mother liquor is returned to the multi-stage atmospheric pressure leaching tank.

[0014] In step (2), the discharge port of the screw conveyor is connected to the inlet of the first-stage atmospheric leaching tank in the multi-stage atmospheric leaching tank by a flange.

[0015] In step (2), the multi-stage atmospheric pressure leaching tank is formed by connecting multiple atmospheric pressure leaching tanks with successively decreasing heights through pipes, and each atmospheric pressure leaching tank is equipped with a stirrer controlled by a motor.

[0016] The leaching conditions in step (2) are a liquid-to-solid mass ratio of 4:1, a leaching temperature of 85℃, and a leaching time of 2 hours.

[0017] In step (4), during the slurry dissolution, the nickel ion concentration is controlled at 110~130 g / L and the iron ion concentration is controlled at 40~60 g / L.

[0018] In step (5), the temperature of the iron removal reaction is 180~200℃, and the oxygen partial pressure is 0.4MPa.

[0019] In step (6), the iron concentration of the overflow liquid A is 3.0~5.0 g / L.

[0020] In step (6), the hematite tailings have an iron content ≥55%, a nickel content <0.5%, and a sulfur content <2%.

[0021] In step (6), the sulfuric acid content of the high-acid mother liquor is 8~10 mol / L.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. This invention utilizes grinding, leaching, leaching solution evaporation and crystallization, pressurized iron precipitation, and iron removal solution evaporation and crystallization to achieve a short-process treatment of medium-grade nickel matte. It also has the advantages of low production and operating costs and flexible product processing, making it highly competitive in the market.

[0024] 2. This invention utilizes a dry ball mill to grind medium-grained nickel matte to a particle size of -280 mesh with a purity greater than 95%. This material is then conveyed to a multi-stage high-acid atmospheric pressure leaching tank for atmospheric pressure leaching. A circulating leaching method is employed, causing iron, nickel, and cobalt sulfates to crystallize during the leaching process. The mother liquor from the crystallization is returned for further circulating leaching, thus achieving the separation of iron, nickel, and cobalt from sulfuric acid. The resulting crystals are dissolved in water to obtain iron, nickel, and cobalt sulfate solutions and copper-containing slag, thereby achieving the separation of copper and nickel. After iron removal from the nickel, iron, and cobalt sulfate solution using a hematite method, hematite slag and a high-acid nickel sulfate solution are produced. To save operating costs, this solution is evaporated and concentrated, producing crude nickel sulfate crystals and a concentrated acid mother liquor. The concentrated acid mother liquor can be returned to the leaching system for circulating leaching. The final product can be sold directly as crude nickel sulfate crystals, or dissolved and purified by extraction to produce refined nickel sulfate crystals or electrolytic nickel products, allowing for flexible processing.

[0025] 3. In this invention, the problem of separating metal ions from sulfuric acid is solved by using concentrated mother liquor leaching, thus realizing the repeated and cyclical use of acid.

[0026] 4. In this invention, the high-acid solution after pressurized iron precipitation is creatively treated by evaporation and crystallization, and the concentrated sulfuric acid concentration is returned to the front-end leaching system. At the same time, it avoids using liquid alkali or soda ash to neutralize sodium ions introduced into the system; or using nickel carbonate to neutralize the sodium sulfate wastewater produced; or using calcium oxide to neutralize the calcium slag produced.

[0027] 5. This invention enables a short-process treatment of nickel matte. By enhancing the acidity of the leaching solution, nickel, iron, and cobalt can be leached under normal pressure. Copper is leached in the form of copper sulfide slag, achieving copper and nickel separation during the leaching process. Precious metals are enriched in the copper slag, achieving a high concentration of precious metals. The concentrated mother liquor recycling leaching mode achieves the separation of iron, nickel, cobalt, and sulfuric acid. After iron removal from hematite, the high-acid solution is evaporated and concentrated, and the resulting high-acid mother liquor is returned to normal pressure leaching for reuse, which can reduce the acid consumption in the front-end leaching and save the cost of alkali consumption required for neutralizing the acid in the back-end iron removal solution. During the evaporation and crystallization process, high-concentration nickel sulfate can be crystallized, while only trace amounts of low-concentration ferric sulfate crystallize out, and most of the ferric sulfate is returned to the front-end leaching process, achieving the effect of secondary iron removal in the final product (nickel sulfate).

[0028] 6. The method of this invention can separate the main metal nickel from the impurity metals copper and iron, and can produce copper slag with high copper content and hematite slag with high iron content, which creates favorable conditions for downstream processing. Attached Figure Description

[0029] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

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

[0031] Figure 2 This is a device connection diagram for the present invention.

[0032] In the diagram: 1—Dry ball mill; 2—Screw conveyor; 3—Multi-stage atmospheric pressure leaching tank; 4—Leaching filter press; 5—Evaporator concentrator; 6—Pulping and dissolving tank; 7—Pulping filter press; 8—Pressurized iron settling kettle; 9—Pressurized thickener; 10—Three-stage CCD washing thickener; 11—Washing filter press; 12—Evaporator crystallizer. Detailed Implementation

[0033] like Figures 1-2 As shown, a process for high-acid, atmospheric-pressure, cyclic leaching of nickel matte includes the following steps:

[0034] (1) Medium nickel matte is fed into a dry ball mill 1 for grinding to obtain finely ground medium nickel matte with a particle size of -280 mesh and greater than 95%.

[0035] This invention employs a dry ball mill 1 primarily because the leaching system needs to maintain a consistent sulfuric acid concentration and cannot introduce external fresh water to dilute the sulfuric acid in any form. Therefore, a dry ball mill 1 is required to process the medium-grade nickel matte. The particle size of the medium-grade nickel matte after grinding must reach -280 mesh or greater than 95% to create favorable conditions for atmospheric pressure leaching.

[0036] (2) Finely ground nickel matte is conveyed via screw conveyor 2 into the first stage of the multi-stage atmospheric leaching tank 3. Simultaneously, concentrated sulfuric acid is added to the first stage for leaching. The liquid-to-solid mass ratio (kg / kg) is 4:1, the leaching temperature is 85℃, and the leaching time is 2 hours. As the leaching reaction proceeds, the acidity of each stage of the atmospheric leaching tank gradually decreases. Acid solution is added promptly during the reaction (return liquid at the rear end) to maintain the sulfuric acid concentration in each stage of the atmospheric leaching tank at ≥6 mol / L. At the end of leaching, hydrogen sulfide gas and leached slurry are obtained. The collected hydrogen sulfide gas is used to prepare sulfur via the Claus process or directly absorbed by liquid alkali.

[0037] Finely ground nickel matte is added to the atmospheric leaching tank via screw conveyor 2. This is mainly because the atmospheric leaching tank is a high-acid leaching tank, and a small amount of hydrogen sulfide gas will be generated during the leaching process. Therefore, it is necessary to take good sealing measures for the atmospheric leaching tank to ensure the directional and concentrated collection of hydrogen sulfide gas. Thus, the discharge port of screw conveyor 2 is connected to the inlet of the first-stage atmospheric leaching tank in the multi-stage atmospheric leaching tank 3 by flange. The inside of screw conveyor 2 is sealed by the finely ground nickel matte and the screw, which can ensure the sealing effect of the atmospheric leaching tank at the feeding position.

[0038] After leaching, the leaching rates of Fe, Co, and Ni can all reach over 98%. During the leaching process, the Cu element in the raw material is suppressed in the slag in the form of Cu2S, and the copper leaching rate is basically 0%. The copper content in the leaching slag can reach about 70%, while the nickel and cobalt contents are 0.6% and 0.05%, respectively, thus achieving a high degree of separation between copper and nickel.

[0039] Among them, the multi-stage atmospheric pressure leaching tank 3 is composed of multiple atmospheric pressure leaching tanks with successively decreasing heights connected in series by pipes, and each atmospheric pressure leaching tank is equipped with a stirrer controlled by a motor.

[0040] (3) The leaching slurry is filtered and separated by leaching filter press 4 to obtain filter residue and leaching filter liquid respectively; the leaching filter liquid is treated by evaporator 5 to obtain condensate A and concentrated mother liquor respectively; the concentrated mother liquor and crystals are not separated and are returned to multi-stage atmospheric pressure leaching tank 3 for circulating leaching, so that iron, nickel and cobalt sulfates crystallize and precipitate during the leaching process, thus achieving the separation of iron, nickel and cobalt from sulfuric acid; condensate A enters slurry dissolving tank 6 and can be used to dissolve iron, nickel and cobalt sulfates in the leaching process.

[0041] The leaching and filtration solution is a saturated solution of iron, nickel, and cobalt sulfates, and the sulfuric acid concentration should be the same as the acidity during the leaching process, which can reach 6 mol / L.

[0042] The volume of the leaching liquid after hydraulic filtration should be the same as the volume of the solution during the leaching process (evaporation is not considered).

[0043] (4) The filter press residue enters the slurry dissolution tank 6, where it is dissolved using fresh water and washing liquid. During slurry dissolution, the nickel ion concentration is controlled at 110~130 g / L and the iron ion concentration at 40~60 g / L. After dissolution, the iron, nickel, and cobalt sulfates enter the solution, which is then filtered through the slurry filter press 7 to obtain copper filter slag (i.e., leaching residue) and a sulfate solution containing iron, nickel, and cobalt. The copper filter slag is then sent to a copper industry company for processing.

[0044] All precious metals are enriched in the leaching and pressure-filtering copper slag, which can achieve the concentration and high enrichment of precious metals.

[0045] (5) The sulfate solution containing iron, nickel, and cobalt is fed into a pressurized iron removal reactor 8, while medium-pressure steam and oxygen are simultaneously supplied to carry out the iron removal reaction at a temperature of 180~200℃ and an oxygen partial pressure of 0.4MPa. After the reaction is completed, the iron-removed slurry is obtained.

[0046] The chemical composition of the sulfate solution containing iron, nickel, and cobalt can be adjusted and controlled within a certain range (by controlling the amount of fresh water added during dissolution). If conditions permit, the nickel ion concentration should be increased as much as possible, mainly to reduce the evaporation of the solution after iron removal, thereby reducing the operating cost of evaporation and crystallization of the solution after iron removal.

[0047] Medium-pressure steam is introduced to provide heat for the iron removal reaction. Under the above reaction conditions, all iron ions in the solution can be precipitated into the slag in the form of hematite.

[0048] (6) After iron removal, the slurry enters the pressure thickener 9 for sedimentation and separation, yielding underflow A and overflow A (i.e., liquid after iron removal). To control the nickel content in the hematite slag, the iron content in the liquid after iron removal can be appropriately relaxed to 3.0~5.0 g / L to improve the nickel ion recovery rate.

[0049] The underflow A enters the three-stage CCD washing and thickening machine 10 for further processing to reduce the nickel and sulfur content of hematite and improve the grade of hematite tailings, yielding underflow B and overflow B respectively. Overflow B is returned to the slurry dissolving tank 6. Underflow B enters the washing filter press 11 to obtain CCD washing filtrate and hematite tailings respectively. The iron ore tailings have an iron content ≥55%, a nickel content <0.5%, and a sulfur content <2%. The CCD washing filtrate is returned to the slurry dissolving tank 6 for slurry dissolution of iron, nickel, and cobalt sulfate crystals. The hematite slag is packaged and sold externally.

[0050] Overflow liquid A (after iron removal) is treated by evaporator crystallizer 12, and the solution temperature can be maintained at around 90℃. Direct entry into the evaporator crystallization system can save on the operating costs of the evaporator crystallization system. After evaporation and crystallization, condensate B, nickel sulfate crystals, and high-acid mother liquor are obtained respectively. Condensate B is returned to the three-stage CCD washing thickener 10 and can be used as washing water for hematite CCD. After washing, it can be returned to the front end of the pulping process to dissolve iron, nickel, and cobalt sulfate crystals, achieving volume balance in the entire process. High-acid mother liquor is returned to the multi-stage atmospheric pressure leaching tank 3. Nickel sulfate crystals can be sold directly or dissolved and purified by extraction to produce refined nickel sulfate crystals or electrolytic nickel products.

[0051] Iron ions in the leaching solution after iron removal are primarily concentrated in the high-acid mother liquor during evaporation and crystallization, thus achieving secondary purification of iron ions through evaporation and crystallization. Simultaneously, since the high-acid mother liquor produced after evaporation of the iron-removed solution also needs to be returned to the multi-stage atmospheric pressure leaching tank 3 for treatment, to ensure volume balance in the leaching system, the iron-removed solution needs to be concentrated to a certain extent. The volume evaporated during concentration should be the same as the volume of the high-acid mother liquor produced after evaporation of the iron-removed solution.

[0052] The main control index for evaporation crystallization is the acid content of the high-acid mother liquor, which should be controlled at 8~10 mol / L sulfuric acid content to ensure that the acid content is higher than the acidity required for leaching. The acidity can be replenished after leaching.

[0053] During the evaporation and crystallization process, nickel sulfate crystals precipitate out. Since the solution still contains 3.0~5.0 g / L of ferric sulfate, some ferric sulfate and cobalt sulfate may be attached to the nickel sulfate crystals. However, most of the ferric sulfate, cobalt sulfate and other impurity elements will be enriched in the high-acid mother liquor and returned to the leaching system. The impurity elements are introduced from copper slag and hematite slag. After cobalt sulfate is enriched to a certain extent, it precipitates out with the nickel sulfate crystals. After the nickel sulfate crystals are dissolved, they are extracted to achieve comprehensive recovery of nickel and cobalt.

[0054] In this invention, the entire process is carried out in a high-acid environment. Therefore, the sealing of the equipment and the absorption of acid mist must be taken seriously to ensure the on-site working environment. At the same time, since the atmospheric pressure leaching system will produce hydrogen sulfide gas, it is necessary to strictly monitor the sealing of the atmospheric pressure leaching tank to avoid hydrogen sulfide leakage.

[0055] Since the production media are all high-acid solutions, the selection of materials for the equipment is crucial. In particular, the multi-stage atmospheric pressure leaching tank 3 produces hydrogen sulfide gas, which requires resistance to both acid and hydrogen sulfide corrosion. It is recommended to use steel lined with rubber and brick, or zirconium or steel lined with zirconium. For other reaction equipment (evaporation crystallizer), it is recommended to use titanium or steel lined with titanium.

[0056] In addition, the volume balance of the entire process relies on the evaporator crystallizer 12. When the production system volume is large, the evaporation capacity of the evaporation system can be increased to improve the concentration of sulfuric acid and ions. When the production system volume is small, the evaporation capacity of the evaporation system can be reduced to reduce the amount of condensate produced. New water needs to be added as required.

[0057] The acid balance of the entire process requires adjustment in conjunction with the evaporator crystallizer 12. By controlling the degree of evaporation and crystallization, the acid concentration of the high-acid mother liquor and the concentrated mother liquor is controlled, ensuring the acidity control of the leaching process. According to metallurgical calculations, the acid consumed by the atmospheric pressure leaching system is much greater than the acid produced by the hematite iron removal system. Therefore, concentrated sulfuric acid needs to be added during the production process to ensure the leaching acidity. Example

[0058] Based on a production scale of 1 t. Ni / h, the required amount of medium-grade nickel matte is 3.125 t. ore / h. During the leaching and filter press residue slurry dissolution, the nickel ion concentration is controlled at 120 g / L, and the sulfuric acid concentration in the high-acid mother liquor from evaporation and crystallization is controlled at 900 g / L.

[0059] The specific implementation process is as follows:

[0060] Medium-grain nickel ore is fed into dry ball mill 1 at a rate of 3.125 t / h to finely grind the medium-grain nickel ore to a particle size of -280 mesh greater than 95%. The finely ground ore powder is connected to the feed port of screw conveyor 2 through the discharge port. The discharge port of screw conveyor 2 is connected to the feed port of atmospheric pressure leaching tank 1. The finely ground medium-grain nickel ore powder is added to the atmospheric pressure leaching tank through screw conveyor 2. The material conveying speed of screw conveyor 2 is controlled at 3.125 t / h by frequency conversion speed regulation, which matches the processing capacity of dry ball mill 1.

[0061] In addition to adding medium-grade nickel matte powder, the atmospheric pressure leaching tank #1 also requires the addition of concentrated mother liquor, high-acid mother liquor, and a small amount of concentrated sulfuric acid. The solid-to-liquid mass ratio of the leaching solution is controlled at 4:1, while maintaining the reaction acidity at 6 mol / L during the leaching process. In atmospheric pressure leaching tanks #2-#4, as the reaction proceeds, the sulfuric acid is gradually consumed, requiring the addition of a small amount of concentrated sulfuric acid to ensure the reaction acidity is maintained at 6 mol / L. Due to the use of concentrated mother liquor circulation leaching, the sulfate in the leaching solution is basically saturated before leaching. As nickel, iron, and cobalt are continuously leached, sulfate continuously precipitates in the form of crystals until only copper sulfide slag remains in the slurry.

[0062] The leached slurry is fed to a leaching filter press 4 for filtration to achieve liquid-solid separation. The volume of the liquid after leaching and filtration is approximately 12.5 m³. 3 After evaporation and concentration, approximately 1.5 t / h of condensate A is discharged, resulting in a volume of 11 m³. 3 / h; After filtration, the slag enters the slurry dissolving tank 6. Simultaneously, 1.5t / h of condensate A from evaporation and concentration, and 7.0t / h of condensate B from evaporation and crystallization are added to the slurry dissolving tank 6 (this portion of water is first sent to the three-stage CCD washing thickener 10 to wash the hematite slag), dissolving the sulfate crystals into the solution, controlling the nickel content to 120g / L and the iron content to 53g / L. The slurry continues to be sent to the slurry filter press 7 for filtration, achieving solid-liquid separation of the copper slag and the sulfate solution. The copper slag, after washing, is sent to the copper company for processing (copper slag chemical composition: copper ≥70%, nickel <0.6%, cobalt <0.05%); the sulfate solution is sent to the pressure iron settling reactor 8 for processing. The pressure-controlled iron settling kettle 8 controls the reaction temperature to 180-200℃, oxygen partial pressure to 0.4MPa, and kettle pressure to 1.2MPa. The produced slurry is thickened by a pressure thickener 9 to achieve solid-liquid separation. The underflow is washed by a three-stage CCD washing thickener 10 to produce hematite slag (chemical composition: iron ≥55%, nickel <0.5%, sulfur <2%), which is then simply packaged and sold. The overflow liquid from the thickener is the liquid after iron removal (chemical composition: nickel 120g / L, iron 3-5g / L). To reduce the loss of nickel ions, the iron ion content of the liquid after iron removal is controlled at 3-5g / L during the iron removal process to improve the nickel yield.

[0063] Before entering the pressure thickener 9, the iron-removed slurry needs to undergo flash evaporation for cooling and depressurization, simultaneously producing flash steam, which is then returned to the atmospheric leaching tank for reuse. If there is any surplus flash steam, it can be used to supplement the evaporation concentration and evaporation crystallization systems. The volume of the liquid after iron removal remains at 8.5 m³. 3 Based on a flow rate of / h (ignoring evaporation volume loss), 7.0t / h of condensate B needs to be evaporated during the evaporation and crystallization process, and the amount of mother liquor produced is 1.5m³. 3 The sulfuric acid content can reach 1000 g / L per hour, and it is also a saturated solution of nickel sulfate. After back leaching, the sulfuric acid can be effectively utilized, and the leached nickel sulfate, iron, cobalt, and other sulfates can be precipitated in a timely manner. The condensate produced by evaporation and crystallization is 7.0 t / h, which is sent to a 10-stage CCD washing and thickening machine; the produced high-acid mother liquor (volume 1.5 m³) 3 The leaching process was repeated ( / h), and the concentrated mother liquor (volume 11.0m³) was collected after evaporation and concentration. 3 The leaching process ( / h) is combined with the atmospheric pressure leaching tank, thus controlling the leaching volume to 12.5m³. 3 / h, to achieve volume balance of the entire process.

Claims

1. A process for high-acid, atmospheric-pressure, cyclic leaching of nickel matte, comprising the following steps: (1) Medium-sized nickel matte is fed into a dry ball mill (1) for grinding to obtain medium-sized nickel matte with a particle size of -280 mesh and a fine grinding content of more than 95%. (2) The finely ground nickel matte is fed into the first stage of the multi-stage atmospheric pressure leaching tank (3) via a screw conveyor (2). At the same time, concentrated sulfuric acid is added to the first stage atmospheric pressure leaching tank for leaching, and the sulfuric acid concentration in each stage of the atmospheric pressure leaching tank is controlled to be ≥6mol / L. After leaching, hydrogen sulfide gas and leaching slurry are obtained respectively. The hydrogen sulfide gas is collected and sulfur is prepared by Claus process or directly absorbed by liquid alkali. (3) The leaching slurry is filtered and separated by a leaching filter press (4) to obtain filter residue and leaching filter liquid respectively; the leaching filter liquid is treated by an evaporator (5) to obtain condensate A and concentrated mother liquor respectively; the concentrated mother liquor is returned to the multi-stage atmospheric pressure leaching tank (3) for circulating leaching; the condensate A enters the slurry dissolving tank (6). (4) The filter press residue enters the slurry dissolution tank (6), and after slurry dissolution using fresh water and washing liquid, it enters the slurry filter press (7) for filtration, to obtain filter press copper slag and sulfate solution containing iron, nickel and cobalt respectively; the filter press copper slag is sent to the copper industry company for processing; during the slurry dissolution, the nickel ion concentration is controlled at 110~130g / L and the iron ion concentration is 40~60g / L; (5) The sulfate solution containing iron, nickel and cobalt is fed into a pressurized iron removal reactor (8), while medium-pressure steam and oxygen are simultaneously supplied to carry out the iron removal reaction, and iron-removed slurry is obtained; ⑹ The iron-removed slurry enters a pressure thickener (9) for sedimentation and separation to obtain underflow A and overflow A respectively; the iron concentration of the overflow A is 3.0~5.0 g / L; The underflow A enters a three-stage CCD washing and thickening machine (10) for processing, yielding underflow B and overflow B respectively; the overflow B is returned to the slurry dissolving tank (6); the underflow B enters a washing filter press (11), yielding CCD washing filtrate and hematite tailings respectively; the CCD washing filtrate is returned to the slurry dissolving tank (6); the hematite slag is packaged and sold; the hematite tailings contain ≥55% iron, <0.5% nickel, and <2% sulfur. The overflow liquid A is processed by the evaporator crystallizer (12) to obtain condensate B, nickel sulfate crystals and high acid mother liquor respectively; the condensate B is returned to the three-stage CCD washing thickener (10); the high acid mother liquor is returned to the multi-stage atmospheric pressure leaching tank (3).

2. The process for high-acid, atmospheric-pressure, cyclic leaching of nickel matte as described in claim 1, characterized in that: In step (2), the discharge port of the screw conveyor (2) is connected to the inlet of the first-stage atmospheric leaching tank in the multi-stage atmospheric leaching tank (3) by a flange.

3. The process for high-acid, atmospheric-pressure, cyclic leaching of nickel matte as described in claim 1, characterized in that: In step (2), the multi-stage atmospheric pressure leaching tank (3) is formed by connecting multiple atmospheric pressure leaching tanks with successively decreasing heights through pipes, and each atmospheric pressure leaching tank is equipped with a stirrer controlled by a motor.

4. The process for high-acid, atmospheric-pressure, cyclic leaching of nickel matte as described in claim 1, characterized in that: The leaching conditions in step (2) are a liquid-to-solid mass ratio of 4:1, a leaching temperature of 85℃, and a leaching time of 2 hours.

5. The process for high-acid, atmospheric-pressure, cyclic leaching of nickel matte as described in claim 1, characterized in that: In step (5), the temperature of the iron removal reaction is 180~200℃, and the oxygen partial pressure is 0.4MPa.

6. The process for high-acid, atmospheric-pressure, cyclic leaching of nickel matte as described in claim 1, characterized in that: In step (6), the sulfuric acid content of the high-acid mother liquor is 8~10 mol / L.

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