Method for improving the quality of nickel-cobalt hydroxide intermediate products and hydrometallurgical treatment method

Abstract

The present invention discloses a method for improving the quality of a nickel-cobalt hydroxide intermediate product and a method for high-pressure leaching hydrometallurgical treatment of laterite nickel ore. The method for improving the quality of the nickel-cobalt hydroxide intermediate product is to improve the quality by combining high-temperature heat treatment with wet acid leaching treatment. The present application can improve the quality of the nickel-cobalt hydroxide intermediate product, and obtain a nickel-cobalt oxide product with low impurities that can be directly sold, and has the advantages of simple process and low cost. Based on the above-mentioned quality-improved product, the laterite nickel ore high-pressure leaching hydrometallurgical treatment is carried out, which simplifies the downstream process, reduces transportation costs, reduces equipment investment, and reduces subsequent extraction pressure.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy, and in particular to a method for improving the quality of a nickel-cobalt hydroxide intermediate product and a high-pressure leaching hydrometallurgical treatment method for laterite nickel ore containing the same. Background Art

[0002] At present, high-pressure leaching hydrometallurgy of limonite-type laterite nickel ore is one of the main process methods of nickel metallurgy. The process flow of this method is: leaching-iron and aluminum removal-precipitation of nickel and cobalt, obtaining a large amount of nickel cobalt hydroxide (MHP) intermediate products, whose impurities mainly include manganese, magnesium, iron, aluminum, etc.; converting MHP into nickel sulfate solution, that is, leaching-impurity removal-extraction separation of impurities and nickel and cobalt, to obtain the final nickel and cobalt product.

[0003] The inventors of the present application have realized that the above process method has the following problems: 1) The nickel-cobalt hydroxide intermediate product needs to be transported during the process, and the transportation process will incur huge freight costs; 2) The extraction and impurity removal system and the nickel-cobalt separation system have huge flow rates, complex procedures, and cumbersome processes, and some evaporation systems need to be built, resulting in increased production investment costs. 3) The reagents that need to be added during impurity removal will introduce other impurities, and the organic back-extraction solution loaded after extraction needs to be further neutralized, etc. Therefore, it is of great significance in the field of metallurgy to provide an efficient treatment method. Summary of the invention

[0004] The object of the present invention is to provide a method for improving the quality of nickel-cobalt hydroxide intermediate products and a laterite nickel ore high-pressure leaching hydrometallurgical treatment method comprising the same. The above object of the present invention is achieved through the following technical solutions.

[0005] According to one aspect of the present invention, a method for improving the quality of a nickel-cobalt hydroxide intermediate product provided by the present invention uses a nickel-cobalt hydroxide intermediate product obtained by precipitating nickel and cobalt by a precipitation method in a high-pressure leaching hydrometallurgical process of laterite nickel ore as a raw material, and adopts a process combining high-temperature heat treatment with wet acid leaching treatment to reduce the water content of the nickel-cobalt hydroxide intermediate product and remove the impurity magnesium element, thereby improving the quality of the nickel-cobalt hydroxide intermediate product.

[0006] Optionally, high temperature heat treatment is first used, followed by wet acid leaching treatment.

[0007] Alternatively, optionally, wet acid leaching treatment is first used, followed by high temperature heat treatment.

[0008] Optionally, during high temperature heat treatment, the temperature is 300°C to 1000°C and the time is 0.5h to 6h.

[0009] Optionally, during high-temperature heat treatment, a rotary kiln is directly used for drying and roasting, or the material is first dried and then fed into a rotary kiln for roasting.

[0010] Optionally, during the wet acid leaching treatment, the pH is controlled to be 4 to 7.5, the temperature is 20° C. to 100° C., and the time is 0.5 h to 4 h.

[0011] Optionally, during the wet acid leaching treatment, water is added for slurrying to control the liquid-solid ratio to (2-8):1; wherein the acid is one or more selected from hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, and carbonic acid.

[0012] Optionally, after the wet acid leaching step, the method further comprises: filtering and drying the filter cake, wherein the drying temperature is 100° C. to 150° C. and the drying time is 2 h to 6 h.

[0013] Optionally, the method further includes: returning the filtrate to the laterite nickel ore wet process system for nickel and cobalt recovery, wherein the filtrate is a solution containing nickel and cobalt impurities.

[0014] Optionally, the raw material has a moisture content of 40% to 70% and a magnesium content of 2% to 5%.

[0015] Optionally, the final product obtained after quality improvement does not contain moisture and has a magnesium content of no more than 0.2%.

[0016] According to another aspect of the present invention, the present invention provides a high-pressure leaching hydrometallurgical treatment method for laterite nickel ore, which comprises: acid dissolving, removing impurities, and extracting the upgraded intermediate product obtained by the method for improving the quality of the nickel-cobalt hydroxide intermediate product as described above to obtain a final nickel-cobalt product.

[0017] Beneficial effects: The present invention starts from improving the quality of the intermediate product nickel cobalt hydroxide, adopts a process combining high-temperature heat treatment with wet acid leaching treatment, improves and optimizes its water content and impurity magnesium, reduces the water content of the nickel cobalt hydroxide intermediate product to zero, removes the magnesium element therein, improves the quality of the nickel cobalt hydroxide intermediate product, and obtains a nickel cobalt oxide product with low impurities that can be directly sold, and has the advantages of simple process and low cost.

[0018] In addition, by improving the quality of the MHP intermediate product in the high-pressure leaching hydrometallurgical treatment of laterite nickel ore, its quality is improved. Based on the above-mentioned quality-improved products, the high-pressure leaching hydrometallurgical treatment of laterite nickel ore is continued, which simplifies the downstream process, reduces transportation costs, reduces equipment investment, and reduces subsequent extraction pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic flow chart of the method for improving the quality of the nickel cobalt hydroxide intermediate product in the present invention.

[0020] Figure 2 It is a schematic flow chart of a method for improving the quality of nickel cobalt hydroxide intermediate products according to one embodiment of the present invention.

[0021] Figure 3 It is a schematic flow chart of a method for improving the quality of nickel cobalt hydroxide intermediate products according to one embodiment of the present invention.

[0022] Figure 4 The present invention is a schematic diagram of a process for high-pressure leaching of laterite nickel ore by hydrometallurgical treatment. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Figure 1 The following is a schematic diagram showing a process flow diagram of a method for improving the quality of a nickel cobalt hydroxide intermediate product provided by the present invention. Figure 1 As shown, the quality of MHP is improved by combining high-temperature heat treatment with wet acid leaching treatment to obtain a product with improved quality.

[0025] This application, starting from the two aspects of water content and impurity magnesium content, adopts high-temperature heat treatment process and wet acid leaching treatment process to reduce the water content of nickel cobalt hydroxide intermediate product to zero, with high nickel and cobalt content, removes magnesium element, and improves the quality of nickel cobalt hydroxide intermediate product. There is no need to change the existing process and equipment, reduce the water content, reduce huge transportation costs, reduce the physical amount of post-processing, and greatly reduce the impurity magnesium content, so that the subsequent extraction pressure is reduced, and there is no need for equipment investment such as evaporation system. It is an efficient process means to improve the quality of MHP, and it is also expected in the subsequent hydrometallurgical treatment of MHP intermediate product refining.

[0026] The invention provides a high-pressure leaching hydrometallurgical treatment method for laterite nickel ore. Starting from the quality of the nickel-cobalt hydroxide intermediate product, the quality of the nickel-cobalt hydroxide intermediate product is improved by the above-mentioned quality improvement method, roasting reduces the physical amount, increases the nickel-cobalt content, removes magnesium, reduces its impact on downstream processes, and reduces the problems of high cost, large equipment investment, and high subsequent extraction pressure in the hydrometallurgical treatment process.

[0027] Figure 2The process of the method for improving the quality of the nickel cobalt hydroxide intermediate product provided in one embodiment of the present invention is schematically shown. The method for improving the quality of the nickel cobalt hydroxide intermediate product provided in this embodiment is to dry the nickel cobalt hydroxide intermediate product filter cake and perform high-temperature heat treatment; then the powder obtained after the high-temperature heat treatment is subjected to wet selective leaching treatment to selectively dissolve the Mg element therein, and other valuable metals remain in the solid. Specifically, Figure 2 As shown, the following steps are included:

[0028] 1) First, the nickel cobalt hydroxide intermediate product is dried to remove the moisture in MHP, the drying temperature is 100°C to 150°C, the drying time is 2h to 6h, and a dried block solid is obtained. Flash drying can be used for drying, and the raw material does not contain moisture after drying.

[0029] Among them, the nickel cobalt hydroxide intermediate product MHP is the nickel cobalt hydroxide intermediate product MHP obtained by precipitation of nickel and cobalt in the high-pressure leaching hydrometallurgical process of laterite nickel ore. The impurities in the raw materials mainly include manganese, magnesium, iron, aluminum, etc. The magnesium content is 2% to 5%, and the water content is 40% to 70%.

[0030] 2) The dried block solid is subjected to high temperature heat treatment at a temperature of 300° C. to 1000° C. for a time of 0.5 h to 6 h to obtain a solid powder.

[0031] High temperature heat treatment can be carried out by high temperature roasting in a rotary kiln, the temperature can be, for example, 450°C, 550°C, 650°C, 750°C, 850°C, 950°C, etc., the time is 0.5h to 6h, the hydroxide is decomposed into oxides, and brown-black powder is obtained after roasting. Manganese, magnesium, iron, and aluminum in the raw materials all exist in the form of hydroxides, which can be effectively decomposed to form oxides under the above conditions. In addition, the inventors of the present application also found that if the temperature is too low, it cannot be completely decomposed, and it is easy to agglomerate and cannot form loose powder; and if the temperature is too high, the energy consumption increases.

[0032] In this embodiment, a drying treatment is performed before high temperature heat treatment, and free water in MHP can be removed by drying treatment. Under the above conditions, free water can be removed quickly and completely in about 4 hours. High temperature and long time will increase energy consumption. Of course, it is not limited to this, and direct drying and roasting in a rotary kiln can also be used.

[0033] After the above treatment, the MHP product with a moisture content of 40% to 70% is dehydrated and converted into an oxide with the same metal content and less physical volume, so that the valuable metal content of the intermediate product is further enriched, saving a large amount of freight in the intermediate links; the above treatment steps can also decompose the basic sulfates of various metals contained in the hydroxide into sulfates.

[0034] 3) The solid powder obtained by high temperature heat treatment is treated by acid leaching to selectively dissolve magnesium, add water for slurrying, control the liquid-solid ratio (2-8):1; for example, it can be 2:1, 4:1, 6:1, etc., control the pH to 4-7.5, the temperature is 20°C-100°C, for example, it can be 40°C, 60°C, 80°C, etc., the time is 0.5h-4h, filter and dry to obtain the intermediate product after upgrading. Among them, the acid can be one or more of hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, carbonic acid, etc.

[0035] After the above wet treatment process, some soluble salts originally entrained in MHP will be directly dissolved by water, such as magnesium sulfate. Since the order of metal precipitation is iron, aluminum, nickel, cobalt, manganese and magnesium, acid washing will wash away some magnesium. By controlling the pH in the range where nickel and cobalt are not dissolved, magnesium oxide is dissolved, acid is added to adjust the pH to 4.5, or carbon dioxide is introduced.

[0036] 4) After acid leaching, the product is filtered and dried to obtain a nickel cobalt oxide powder product with low impurities. The product can be sold after packaging, which reduces the subsequent processing cost.

[0037] In addition, the treated solution containing nickel and cobalt impurities can be returned to the laterite nickel ore wet process system for nickel and cobalt recovery. For example, the solution after iron and aluminum removal is mixed to a first stage of nickel and cobalt precipitation, and the solution after iron and aluminum removal is returned to a first stage and mixed to a second stage of nickel and cobalt precipitation.

[0038] Figure 3 The process of the second nickel cobalt hydroxide intermediate product quality improvement method provided in one embodiment of the present invention is schematically shown. The method for improving the quality of the nickel cobalt hydroxide intermediate product provided in this embodiment is different from the previous embodiment in that the acid leaching treatment is placed first, that is, Mg is first removed from the MHP slurry, and then filtering and high-temperature treatment are performed, thereby improving the quality of the nickel cobalt hydroxide intermediate product. Specifically, Figure 2 As shown, the following steps are included:

[0039] 1) The nickel cobalt hydroxide intermediate product is subjected to an acid leaching treatment method to selectively dissolve the magnesium element, and a filter cake is obtained by filtration. The specific acid leaching treatment conditions are the same as those in the previous embodiment.

[0040] 2) Drying the filter cake at a drying temperature of 100° C. to 150° C. for a drying time of 2 h to 6 h, and removing moisture from the filter cake by drying.

[0041] 3) The solid obtained after drying is subjected to high-temperature heat treatment at a temperature of 300° C. to 1000° C. for a time of 0.5 h to 4 h to obtain an upgraded intermediate product.

[0042] Based on the nickel-cobalt hydroxide intermediate product obtained by precipitation of nickel and cobalt in the high-pressure leaching hydrometallurgical process of laterite nickel ore, this application adopts a process combining high-temperature heat treatment and wet acid leaching treatment to improve the quality of the nickel-cobalt hydroxide intermediate product.

[0043] Figure 2 and Figure 3 Two combined methods are schematically shown, one is calcination followed by magnesium removal, and the other is magnesium removal followed by calcination. Based on the water content of MHP itself, it is preferred to first remove magnesium by wet method, then dry it and then treat it by pyrolysis; compared with the lifting method of first drying and pyrolysis, then wet treatment, and then drying, it can further reduce energy consumption under the condition of basically the same process effect.

[0044] Figure 4 A high-pressure leaching hydrometallurgical treatment method for laterite nickel ore provided in one embodiment of the present invention is schematically shown, comprising:

[0045] 1) High-pressure leaching is performed on the laterite nickel ore to remove iron and aluminum, and nickel and cobalt are precipitated by precipitation to obtain nickel and cobalt hydroxide intermediate products. Among them, high-pressure leaching of HPAL, for example, adding sulfuric acid in a pressure autoclave at 250°C, leaches out the valuable elements in the laterite nickel ore, and impurities are also leached out. Generally, limestone is first used to remove iron and aluminum, and then nickel and cobalt are precipitated to form MHP intermediate products. The precipitation method includes one of the active magnesium oxide or magnesium hydroxide precipitation method, the sodium hydroxide precipitation method, and the calcium oxide or calcium hydroxide precipitation method.

[0046] The nickel cobalt hydroxide intermediate product obtained in this step has a water content in the range of 40% to 70%, and a magnesium content of 2% to 5%, which is higher than other impurities. Among them, the nickel cobalt hydroxide intermediate product obtained by the magnesium oxide precipitation method has a higher magnesium content, generally 3% to 5%, while the nickel cobalt hydroxide intermediate product obtained by the sodium hydroxide and lime milk precipitation method has a lower magnesium content, generally 2% to 3%. The high content of impurity magnesium will cause a higher subsequent extraction pressure, and it is also necessary to build a magnesium sulfate evaporation system for post-treatment, which requires a large equipment investment.

[0047] 2) The nickel cobalt hydroxide intermediate product is improved in quality by the nickel cobalt hydroxide intermediate product quality improvement method of the present invention to obtain an improved intermediate product. The improved intermediate product does not contain water, and the impurity magnesium content is reduced, and magnesium can be effectively removed to no more than 0.2%.

[0048] 3) The intermediate product after upgrading is acid-dissolved, impurities removed, and extracted to obtain a nickel-cobalt product. Acid dissolution, impurity removal, and extraction are all performed by conventional methods. In this step, the intermediate product after upgrading is subjected to the removal of magnesium, the physical amount of post-processing is reduced, the impurity magnesium content is greatly reduced, the extraction pressure is reduced, the steps of extracting magnesium, magnesium stripping to form a magnesium sulfate solution, and evaporating and crystallizing to produce magnesium sulfate heptahydrate are omitted, the process is simplified, and the investment cost is reduced.

[0049] The technical solution of the present invention is further described below in conjunction with specific embodiments:

[0050] Example 1

[0051] Sodium hydroxide is used to precipitate the MHP product (nickel 39%, cobalt 3.5%, magnesium 3%, and water content 65%). First, it is dried, and the drying temperature is controlled at 120°C for 4 hours; the dried block solid is subjected to high-temperature heat treatment at 900°C for 2 hours. Secondly, the brown-black powder obtained by high-temperature heat treatment is treated by sulfuric acid acid leaching and stirring, and the pH is controlled at 6 for 2 hours, and the temperature is controlled at room temperature 40°C. After the treatment, it is filtered and dried to become the upgraded product. After measurement, the product does not contain water, and contains 55% nickel, 5.3% cobalt, and 0.05% magnesium.

[0052] Example 2

[0053] First, the laterite nickel ore hydrometallurgical MHP product (dry magnesium content of 2.1%) with a water content of 65% was roasted at 800°C for 2 hours to obtain a brown-black powder. Secondly, the brown-black powder was slurried with water, the liquid-to-solid ratio was controlled at 2:1, the temperature was 60 degrees, the time was 2 hours, the pH was adjusted to 5.0 with sulfuric acid, filtered and washed, and dried to obtain a low-impurity nickel-cobalt oxide powder product that can be directly sold. The nickel and cobalt leaching rates were 0.12% and 0.56% respectively, and the magnesium leaching rate was >90%. After testing, the magnesium content in the final nickel-cobalt oxide product was only 0.13%.

[0054] Example 3

[0055] Sodium hydroxide is used to precipitate the MHP product (nickel 39%, cobalt 3.5%, magnesium 3%, and water content 65%). First, the carbonic acid leaching and stirring method is used to treat it, and carbon dioxide is introduced to control the pH at 4 for 2 hours, and the temperature is controlled at room temperature 40°C. Secondly, the filter cake is dried, and the drying temperature is controlled at 120°C for 4 hours; the dried block solid is subjected to high-temperature treatment at 900°C for 2 hours. The obtained solid is the final product. After measurement, the product does not contain water, contains 51% nickel, 4.9% cobalt, and 0.2% magnesium.

[0056] Example 4

[0057] First, the laterite nickel ore is subjected to high-pressure leaching at a temperature of 250°C, iron and aluminum are removed by limestone neutralization, and nickel and cobalt are precipitated by sodium hydroxide precipitation to obtain the nickel-cobalt hydroxide intermediate product MHP. The product has a water content of 63% and a magnesium content of 2.5%.

[0058] Secondly, the nickel cobalt hydroxide intermediate product MHP is first subjected to a drying and high-temperature heat treatment, wherein it is dried at 150°C for 3 hours and calcined at 800°C for 3 hours; then acid leaching treatment is adopted, carbon dioxide is introduced, the pH value is controlled at 5, the temperature is kept at room temperature, and the time is 4 hours to improve the quality, and the improved intermediate product is obtained, which contains 0.15% magnesium.

[0059] Finally, the intermediate product after upgrading is acid-dissolved with sulfuric acid, impurities such as manganese, copper, and zinc are removed with p204, and nickel and cobalt are separated and cobalt is extracted with p507 extractant to obtain the final nickel-cobalt product. Compared with the case without upgrading, the extraction pressure is lower.

[0060] Compared with the prior art, some embodiments of the present invention also have the following advantages:

[0061] (1) The water content of the nickel cobalt hydroxide intermediate product obtained by the precipitation method of nickel cobalt in the prior art is high, generally 40% to 70%, among which the magnesium oxide precipitation method is relatively low, but also up to 45%. Due to the high water content, the transportation of MHP from the production site to the refinery is equivalent to transporting more than half of the water, which consumes huge freight. The present application reduces the water content of the nickel cobalt hydroxide intermediate product by starting from the water content, thereby reducing the transportation cost of MHP.

[0062] (2) The nickel content obtained by precipitating nickel and cobalt using magnesium oxide precipitation is only about 35%, while that obtained by using sodium hydroxide precipitation can reach about 40%. The physical quantity is too large, which causes inconvenience to subsequent processing. From the perspective of physical quantity, this application reduces the physical quantity by increasing the dry basis valuable element content of the nickel and cobalt hydroxide intermediate product, which makes it more convenient for subsequent processing after improvement.

[0063] (3) The magnesium content of MHP obtained by different precipitation methods is different. The magnesium content obtained by the magnesium oxide precipitation method is relatively high, generally 3% to 5%, and the magnesium content obtained by the sodium hydroxide and lime milk precipitation method is relatively low, generally 2% to 3%. The present application reduces the impurity content in the nickel cobalt hydroxide intermediate product, especially the magnesium content therein, thereby reducing the subsequent extraction pressure and reducing the equipment investment cost, thereby avoiding the problem of high investment cost caused by the magnesium sulfate evaporation system that needs to be built in the prior art.

[0064] The description of the present invention is given for the purpose of illustration and description, and is not intended to be exhaustive or to limit the invention to the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for particular uses.

Claims

1. A high pressure leaching hydrometallurgical treatment method for laterite nickel ore, characterized in that: include: Leaching laterite nickel ore under high pressure to remove iron and aluminum, and using a precipitation method to precipitate nickel and cobalt to obtain a nickel-cobalt hydroxide intermediate product; wherein the nickel-cobalt hydroxide intermediate product has a water content of 40% to 70% and a magnesium content of 2% to 5%; The nickel-cobalt hydroxide intermediate product quality improvement method is used to improve the quality of the nickel-cobalt hydroxide intermediate product to obtain an improved intermediate product; wherein the improved intermediate product does not contain water and has a magnesium content of no more than 0.2%; The intermediate product after upgrading is subjected to acid dissolution, impurity removal and extraction to obtain a final nickel-cobalt product; The method for improving the quality of the nickel cobalt hydroxide intermediate product is to reduce the water content of the nickel cobalt hydroxide intermediate product and remove the impurity magnesium element by combining high-temperature heat treatment with wet acid leaching treatment to improve the quality of the nickel cobalt hydroxide intermediate product; During the high-temperature heat treatment, a rotary kiln is directly used for drying and roasting at a temperature of 300°C to 1000°C for 0.5h to 6h to decompose the hydroxide into oxides and the basic sulfates of various metals included into sulfates to obtain a solid powder. Alternatively, first drying at a drying temperature of 100°C to 150°C for 2h to 6h, then feeding into a rotary kiln for roasting at a temperature of 300°C to 1000°C for 0.5h to 6h, decomposing the hydroxide into oxides, and decomposing the basic sulfates of various metals into sulfates, to obtain a solid powder; During wet acid leaching treatment, the pH is controlled at 4-6, the temperature is 20°C-100°C, and the time is 0.5h-4h.

2. The high pressure leaching hydrometallurgical treatment method for laterite nickel ore according to claim 1, characterized in that: When improving quality, high temperature heat treatment is used first, followed by wet acid leaching treatment.

3. The high pressure leaching hydrometallurgical treatment method for laterite nickel ore according to claim 1, characterized in that: When improving quality, wet acid leaching treatment is used first, followed by high-temperature heat treatment.

4. The high pressure leaching hydrometallurgical treatment method for laterite nickel ore according to claim 1, characterized in that: When the quality is improved, during the wet acid leaching treatment, water is added for slurrying to control the liquid-to-solid ratio (2-8):1; wherein the acid is one or more selected from hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, and carbonic acid.

5. The high pressure leaching hydrometallurgical treatment method for laterite nickel ore according to claim 2, characterized in that: When the quality is improved, after the wet acid leaching treatment step, it also includes: filtering and drying the filter cake, wherein the drying temperature is 100° C. to 150° C. and the drying time is 2 h to 6 h.

6. The high-pressure leaching hydrometallurgical treatment method for laterite nickel ore according to claim 5, characterized in that: Also includes: The filtrate is returned to the laterite nickel ore wet process system for nickel and cobalt recovery, and the filtrate is a solution containing nickel and cobalt impurities.

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