Method for treating lateritic nickel ores

Abstract

The present invention belongs to the technical field of hydrometallurgy, and provides a method for treating lateritic nickel ores. The treatment method achieves both the recovery of nickel and cobalt and the production of a by-product, i.e. a ferrosilicon alloy, by means of beneficiation, high-pressure acid leaching, cyclic leaching and ore pulp neutralization, CCD washing, underflow filter pressing, and reduction smelting. In the method, on the basis of the extraction of nickel and cobalt by means of existing conventional methods, reduction smelting is performed on leaching residues obtained from the high-pressure acid leaching of high-silicon lateritic nickel ores, so as to obtain a ferrosilicon alloy; therefore, not only environmental protection problems caused by the generation of a large amount of leaching residues are solved, but iron and silicon are also productized and made to be high-value-added products. In the method, the leaching rates of nickel and cobalt are high after high-pressure acid leaching is utilized; moreover, due to the fact that iron is essentially in the form of hematite at a high temperature and high pressure, the consumption of sulfuric acid and lime in a subsequent iron removal process is low, and good economic returns are yielded; the comprehensive recovery of elements such as nickel, cobalt, iron and silicon is achieved by means of step-by-step enrichment and purification; and the method has significant advantages in terms of the treatment of high-silicon and high-iron lateritic nickel ores.

Description

A method for processing laterite nickel ore

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to a Chinese patent application filed with the Patent Office of China on January 18, 2024, with application number 202410075172.9 and invention name “A method for processing laterite nickel ore”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application belongs to the technical field of hydrometallurgy, and specifically relates to a method for processing laterite nickel ore. Background Art

[0004] In recent years, the rapid development of the new energy vehicle industry has led to a surge in demand for lithium-ion batteries containing nickel, cobalt, and manganese. This has driven a rapid increase in the consumption of battery-grade chemicals such as nickel sulfate, cobalt sulfate, and manganese sulfate. Due to the increasing depletion of traditional nickel sulfide ore resources, the efficient development of laterite nickel ore has become a hot topic.

[0005] At present, the current processing methods of laterite nickel ore are mainly as follows:

[0006] Existing patent documents disclose a clean production method for separating and comprehensively utilizing iron from nickel, cobalt, and silicon in the hydrochloric acid atmospheric pressure leaching process of laterite nickel ore. The process steps of this invention include grinding-leaching-hydrolysis-filtration to obtain a silica filter cake as a building material raw material, neutralization-filtration-washing-drying of the filtrate to obtain high-grade iron concentrate, and impurity removal-extraction-precipitation-electrolysis of the neutralized filtrate to obtain a nickel-cobalt product. This document solves the problems of difficult treatment and high acid consumption of atmospheric pressure leaching solution of laterite nickel ore, and realizes the separation and comprehensive utilization of nickel, cobalt, and iron. However, when the iron content in the raw material is high, due to the large amount of iron leaching during the atmospheric pressure leaching process, a large amount of serpentine-type laterite nickel ore needs to be consumed for neutralization and iron removal, the batching process is complicated, and the iron concentrate and silica products obtained have low added value.

[0007] The current industrialized method for processing laterite nickel ore involves: laterite nickel ore processing - beneficiation - high-pressure acid leaching - circulating leaching and pre-neutralization - CCD washing - iron and aluminum removal - nickel and cobalt precipitation to obtain a nickel-cobalt intermediate. The leached residue and iron and aluminum slag undergo CCD washing and tailings neutralization before being sent to deep-sea landfill or filtered and stored. This process consumes little acid and alkali, has a high nickel and cobalt recovery rate, and offers low operating costs. However, this process only recovers nickel and cobalt from the laterite nickel ore, and does not comprehensively recover elements such as iron and silicon. When the silicon content in the raw material is relatively high, the amount of leached residue is large. As environmental protection requirements in construction sites become increasingly stringent, the trend is to decontaminate and commercialize leached residue and iron and aluminum slag. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present application is to overcome the defects of the existing methods for treating laterite nickel ore, such as the failure to recycle elements such as silicon and iron, or the low added value of the recycled products, the large amount of leaching residue, and the poor environmental benefits, thereby providing a method for treating laterite nickel ore.

[0009] To this end, this application provides the following technical solutions:

[0010] The present application provides a method for processing laterite nickel ore, comprising the following steps:

[0011] S1, beneficiating laterite nickel ore to obtain ore pulp;

[0012] S2, subjecting the slurry to high-pressure acid leaching and flash evaporation to obtain leached slurry;

[0013] S3, performing cyclic leaching and slurry neutralization on the leached slurry to obtain a neutralized slurry;

[0014] S4, performing CCD countercurrent washing on the neutralized slurry to obtain underflow and overflow, and recovering nickel and cobalt from the overflow;

[0015] S5, performing filter pressing on the underflow to obtain leaching residue and filtrate;

[0016] S6, reducing and smelting the leached slag to obtain ferrosilicon alloy and slag.

[0017] Optionally, in step S6, the reduction smelting temperature is 1400-1700° C., and the reduction smelting time is 2-4 hours.

[0018] Optionally, in step S6, the reduction smelting uses at least one of blue coke and coke as a reducing agent;

[0019] And / or, the reducing agent is 80%-100% of the mass of the leaching residue.

[0020] Optionally, in step S6, pellets or silica are added according to the components in the leached residue and the composition of the target product ferrosilicon.

[0021] In the actual process, silica is generally needed to be supplemented. Pellets are only added when the silicon content in the leaching slag is high and ferrosilicon with a low silicon content is produced.

[0022] Optionally, in step S2, the high-pressure acid leaching uses a concentration of 20-70 g / L sulfuric acid, a temperature of 180-255° C., a mass ratio of leachate to ore of 1.5-4, a leaching time of 1-3 h, and a leaching pressure of 1.5-4.5 MPa.

[0023] Optionally, in step S2, in the flash evaporation step S1, the particle size of the minerals in the slurry is ≤100 mesh;

[0024] And / or, the solid content of the slurry is 20-40 wt%.

[0025] Optionally, in step S3, the pH at the end point of the cyclic leaching and slurry neutralization is 1-2, the temperature is 60-90°C, the mass ratio of the leachate to the ore is 2-4, and the leaching time is 2-4h.

[0026] The circulating leaching and slurry neutralization process utilizes the acid-consuming materials such as the return material obtained in the nickel-cobalt recovery process to not only leach the nickel and cobalt in the acid-consuming materials, but also neutralizes the residual acid in the leached slurry obtained after high-pressure acid leaching.

[0027] Optionally, in step S4, the mass ratio of the wash water of the CCD washing to the solids in the ore pulp is 2 to 4.

[0028] In this application, the wash water is a return liquid that contains almost no nickel and cobalt, and is generally the solution after nickel and cobalt are precipitated during the S4 nickel and cobalt recovery process.

[0029] Optionally, in step S5, the obtained filtrate is combined with the overflow in step S4.

[0030] In this application, the main components of laterite nickel ore are as follows:

[0031] Table 1

[0032] "Others" mainly consist of oxygen and a small amount of mineral elements.

[0033] The technical solution of this application has the following advantages:

[0034] The processing method of laterite nickel ore provided in this application is to recover nickel and cobalt by means of mineral processing-high-pressure acid leaching-circulating leaching and slurry neutralization-CCD washing-underflow filter press-reduction smelting, and produce ferrosilicon alloy as a by-product. Based on the existing conventional method for extracting nickel and cobalt, this method reduces and smelts the leaching residue of high-pressure acid leaching of high-silicon laterite nickel ore to obtain ferrosilicon alloy, which not only solves the environmental problems caused by the production of a large amount of leaching residue, but also realizes the productization and high added value of iron and silicon. After high-pressure acid leaching is adopted in this application, the nickel and cobalt leaching rate is high, and because iron exists basically in the form of hematite under high temperature and high pressure, the consumption of lime in sulfuric acid and subsequent iron removal processes is low and the economic benefit is good. The comprehensive recovery of elements such as nickel, cobalt, iron and silicon is achieved through step-by-step enrichment and purification. This process scheme has great advantages for the treatment of high-silicon and high-iron laterite nickel ore.

[0035] The processing method of laterite nickel ore provided in the present application can supplement pellets or silica according to the iron and silicon content in the leaching residue and the type of ferrosilicon product, and the products are flexible and diverse. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0037] FIG1 is a process flow chart of a method for treating laterite nickel ore provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] The following examples are provided to further better understand the present application, but are not limited to the best implementation mode described herein, and do not limit the content and protection scope of the present application. Any product identical or similar to the present application obtained by anyone under the inspiration of the present application or by combining the features of the present application with other prior arts shall fall within the scope of protection of the present application.

[0039] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0040] In order to facilitate comparison between data, the composition of the laterite nickel ore selected in the following examples and comparative examples of this application is shown in the following table:

[0041] Table 2

[0042] Example 1

[0043] This embodiment provides a method for processing laterite nickel ore, the process flow of which is shown in FIG1 and specifically comprises the following steps:

[0044] (1) performing beneficiation on laterite nickel ore to obtain laterite nickel ore slurry, waste rock, sawdust, etc.; wherein the particle size of the minerals in the laterite nickel ore slurry after beneficiation is less than 100 mesh and the solid content is 30%;

[0045] (2) High-pressure acid leaching is performed on the laterite nickel ore pulp, using sulfuric acid as a leaching agent and high-pressure steam as a heat source, and after leaching, the leached pulp is obtained by multi-stage flash cooling; wherein, the high-pressure acid leaching uses sulfuric acid with a concentration of 70g / L, a temperature of 255°C, a liquid-to-solid ratio (the mass ratio of the leachate to the ore) of 2, a leaching time of 1h, and a leaching pressure of 4.5MPa;

[0046] (3) Flash evaporation is performed on the leached pulp to cool it down to about 100°C, and the leaching is circulated. Then, an alkaline substance (generally the secondary iron-aluminum removal pulp and the secondary nickel-cobalt precipitation pulp obtained in the nickel-cobalt recovery process) is used for neutralization to obtain a neutralized pulp; the pH value of the pulp neutralization endpoint is 1, the temperature is 90°C, the liquid-solid ratio (the mass ratio of the leachate to the ore) is 3, and the leaching time is 4h;

[0047] (4) The neutralized slurry is subjected to CCD countercurrent washing to obtain an underflow and an overflow, and the overflow is subjected to iron removal and nickel and cobalt precipitation (wherein, limestone is added for both primary and secondary iron removal, sodium hydroxide is added for primary nickel and cobalt precipitation, and lime milk is added for secondary nickel and cobalt precipitation, the same below) and other nickel and cobalt recovery; the wash water ratio (mass ratio of wash water to solids in the slurry) of the CCD washing is 2, and the wash water is the precipitated liquid obtained by nickel and cobalt precipitation;

[0048] (5) filter pressing the CCD washing underflow to obtain leaching residue and filtrate, which is then incorporated into the CCD overflow;

[0049] (6) The leached slag is subjected to reduction smelting to obtain ferrosilicon and slag; in the reduction smelting process, not only is it necessary to add blue coke as a reducing agent, but also it is necessary to supplement pellets or silica according to the components in the leached slag and the composition of the target product ferrosilicon. In this embodiment, the amount of blue coke added is 90% of the mass of the leached slag, the reduction smelting temperature is 1500°C, and the time is 3h. After testing, the composition of iron in the leached slag is 32%, and silicon is 32%. The silicon content in the production target product ferrosilicon is 40%, and the supplemented pellets containing 85% iron (generally containing 85% iron, the rest is silicon dioxide, oxygen, calcium, etc.) account for 18.8% of the mass of the leached slag.

[0050] Example 2

[0051] This embodiment provides a method for processing laterite nickel ore, the process flow of which is shown in FIG1 and specifically comprises the following steps:

[0052] (1) performing beneficiation on laterite nickel ore to obtain laterite nickel ore slurry, waste rock, sawdust, etc.; wherein the particle size of the minerals in the laterite nickel ore slurry after beneficiation is less than 100 mesh and the solid content is 35%;

[0053] (2) High-pressure acid leaching is performed on the laterite nickel ore pulp, using sulfuric acid as a leaching agent and high-pressure steam as a heat source, and after leaching, the leached pulp is obtained by multi-stage flash cooling; wherein, the high-pressure acid leaching uses sulfuric acid with a concentration of 50g / L, a temperature of 220°C, a liquid-to-solid ratio (the mass ratio of the leachate to the ore) of 2, a leaching time of 2h, and a leaching pressure of 4MPa;

[0054] (3) flash evaporation is performed on the leached pulp to cool it down to about 100°C, and then cyclic leaching and pulp neutralization are performed to obtain neutralized pulp; the pH value at the end point of the cyclic leaching and pulp neutralization is 1.5, the temperature is 80°C, the liquid-solid ratio (the mass ratio of the leachate to the ore) is 3, and the leaching time is 3h;

[0055] (4) CCD countercurrent washing is performed on the neutralized slurry to obtain an underflow and an overflow, and the overflow is subjected to iron removal and nickel and cobalt precipitation and other nickel and cobalt recovery; the wash water ratio (mass ratio of wash water to solids in the slurry) of the CCD washing is 3, and the wash water is the precipitated liquid obtained by nickel and cobalt precipitation;

[0056] (5) filter pressing the CCD washing underflow to obtain leaching residue and filtrate, which is then incorporated into the CCD overflow;

[0057] (6) The leached slag is subjected to reduction smelting to obtain ferrosilicon and slag; in the reduction smelting process, not only is it necessary to add blue coke as a reducing agent, but also it is necessary to supplement pellets or silica according to the composition of the leached slag and the type of ferrosilicon. In this embodiment, the amount of blue coke added is 80% of the mass of the leached slag, the reduction smelting temperature is 1400°C, the time is 4 hours, the silicon content in the target product ferrosilicon is 60%, and silica containing 98% silicon dioxide (silica generally contains 98% silicon dioxide, and the rest are aluminum, iron, calcium, magnesium, oxygen and other elements, the same below) is supplemented to account for 35% of the mass of the leached slag.

[0058] Example 3

[0059] This embodiment provides a method for processing laterite nickel ore, the process flow of which is shown in FIG1 and specifically comprises the following steps:

[0060] (1) performing beneficiation on laterite nickel ore to obtain laterite nickel ore slurry, waste rock, sawdust, etc.; wherein the particle size of the minerals in the laterite nickel ore slurry after beneficiation is less than 100 mesh and the solid content is 20%;

[0061] (2) High-pressure acid leaching is performed on the laterite nickel ore pulp, using sulfuric acid as a leaching agent and high-pressure steam as a heat source, and after leaching, the leached pulp is obtained by multi-stage flash cooling; wherein, the high-pressure acid leaching uses sulfuric acid with a concentration of 30g / L, a temperature of 200°C, a liquid-to-solid ratio (the mass ratio of the leachate to the ore) of 2, a leaching time of 2h, and a leaching pressure of 3.5MPa;

[0062] (3) Flash evaporation is performed on the leached pulp to cool it down to about 100°C, and then cyclic leaching and pulp neutralization are performed to obtain neutralized pulp; the pH value at the end point of the cyclic leaching and pulp neutralization is 2, the temperature is 90°C, the liquid-solid ratio (the mass ratio of the leachate to the ore) is 2, and the leaching time is 4 hours;

[0063] (4) performing CCD countercurrent washing on the neutralized slurry to obtain underflow and overflow, and performing iron removal and nickel and cobalt precipitation on the overflow to recover nickel and cobalt; the wash water ratio (mass ratio of wash water to solids in the slurry) of the CCD washing is 4, and the wash water is the precipitated liquid obtained by nickel and cobalt precipitation;

[0064] (5) filter pressing the CCD washing underflow to obtain leaching residue and filtrate, which is then incorporated into the CCD overflow;

[0065] (6) The leached slag is subjected to reduction smelting to obtain ferrosilicon and slag; in the reduction smelting process, not only is it necessary to add semi-coke as a reducing agent, but also it is necessary to supplement pellets or silica according to the composition of the leached slag and the type of ferrosilicon. In this embodiment, the amount of semi-coke added is 100% of the mass of the leached slag, the reduction smelting temperature is 1700°C, the time is 2h, the silicon content in the target product ferrosilicon is 80%, and the supplemented silica containing 98% silicon dioxide accounts for 210% of the mass of the leached slag.

[0066] Example 4

[0067] This embodiment provides a method for processing laterite nickel ore, the process flow of which is shown in FIG1 and specifically comprises the following steps:

[0068] (1) performing beneficiation on laterite nickel ore to obtain laterite nickel ore slurry, waste rock, sawdust, etc.; wherein the particle size of the minerals in the laterite nickel ore slurry after beneficiation is less than 100 mesh and the solid content is 25%;

[0069] (2) High-pressure acid leaching is performed on the laterite nickel ore pulp, using sulfuric acid as a leaching agent and high-pressure steam as a heat source, and after leaching, the leached pulp is obtained by multi-stage flash cooling; wherein, the concentration of high-pressure acid leaching used is 20g / L sulfuric acid, the temperature is 180°C, the liquid-solid ratio (the mass ratio of the leachate to the ore) is 4, the leaching time is 3h, and the leaching pressure is 1.5MPa;

[0070] (3) Flash evaporation is performed on the leached pulp to cool it down to about 100°C, and then cyclic leaching and pulp neutralization are performed to obtain neutralized pulp; the pH value at the end point of the cyclic leaching and pulp neutralization is 1.5, the temperature is 90°C, the liquid-solid ratio (the mass ratio of the leachate to the ore) is 5, and the leaching time is 1 hour;

[0071] (4) CCD countercurrent washing is performed on the neutralized slurry to obtain an underflow and an overflow, and the overflow is subjected to iron removal and nickel and cobalt precipitation and other nickel and cobalt recovery; the wash water ratio (mass ratio of wash water to solids in the slurry) of the CCD washing is 3, and the wash water is the precipitated liquid obtained by nickel and cobalt precipitation;

[0072] (5) filter pressing the CCD washing underflow to obtain leaching residue and filtrate, which is then incorporated into the CCD overflow;

[0073] (6) The leached slag is subjected to reduction smelting to obtain ferrosilicon and slag; in the reduction smelting process, not only is it necessary to add semi-coke as a reducing agent, but also it is necessary to supplement pellets or silica according to the composition of the leached slag and the type of ferrosilicon. In this embodiment, the amount of semi-coke added is 95% of the mass of the leached slag, the reduction smelting temperature is 1600°C, the time is 2.5h, the silicon content in the target product ferrosilicon is 70%, and the supplemented silica containing 98% silicon dioxide accounts for 163% of the mass of the leached slag.

[0074] The calculation method of the recovery rate of each element in Examples 1-4 is:

[0075] Element recovery rate = corresponding element amount in product / corresponding element amount in raw material × 100%.

[0076] The specific recovery rates are shown in the table below:

[0077] Table 3

[0078] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for treating laterite nickel ore, characterized in that, It includes the following steps: S1. Beneficiate laterite nickel ore to obtain pulp; S2. Subject the above pulp to high-pressure acid leaching and flash evaporation to obtain the leached pulp; S3. Subject the leached pulp to cyclic leaching and pulp neutralization to obtain the neutralized pulp; S4. Subject the neutralized pulp to CCD countercurrent washing to obtain underflow and overflow, and recover nickel and cobalt from the overflow; S5. Filter-press the underflow to obtain leached residue and filtrate; S6. Carry out reduction smelting on the leached residue to obtain ferrosilicon alloy and slag.

2. The treatment method of laterite nickel ore according to claim 1, characterized in that, In step S6, the temperature of the reduction smelting is 1400 - 1700 °C, and the reduction smelting time is 2 - 4 h.

3. The method for treating laterite nickel ore according to claim 1, characterized in that, In step S6, the reduction smelting uses at least one of semi-coke and coke as the reducing agent.

4. The method for treating laterite nickel ore according to claim 3, characterized in that, The reducing agent is 80% - 100% of the mass of the leached residue.

5. The treatment method of laterite nickel ore according to any one of claims 1-4, characterized in that, In step S6, pellet ore or silica is supplemented according to the components in the leached residue and the composition of the target product ferrosilicon.

6. The method for treating laterite nickel ore according to any one of claims 1-5, characterized in that, In step S2, the high-pressure acid leaching uses sulfuric acid with a concentration of 20 - 70 g / L, the temperature is 180 - 255 °C, the mass ratio of the leaching solution to the ore is 1.5 - 4, the leaching time is 1 - 3 h, and the leaching pressure is 1.5 - 4.5 MPa.

7. The treatment method of laterite nickel ore according to claim 6, characterized in that, In step S2, in the flash evaporation step S1, the particle size of the minerals in the pulp ≤ 100 mesh; And / or, the solid content of the pulp is 20 - 40 wt%.

8. The method for treating laterite nickel ore according to any one of claims 1-7, characterized in that, In step S3, the pH at the end of cyclic leaching and pulp neutralization is 1 - 2, the temperature is 60 - 90 °C, the mass ratio of the leaching solution to the ore is 2 - 4, and the leaching time is 2 - 4 h.

9. The method for treating laterite nickel ore according to any one of claims 1-8, characterized in that, In step S4, the mass ratio of the washing water for CCD washing to the solid in the pulp is 2 - 4.

10. The treatment method of laterite nickel ore according to any one of claims 1-9, characterized in that, In step S5, the obtained filtrate is combined with the overflow in step S4.

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