Method for preparing MHP based on oxidation precipitation method

Abstract

The invention relates to a method for preparing MHP based on an oxidation precipitation method, and the method comprises the following steps: mixing laterite-nickel ore iron and aluminum removed liquid, a composite oxidant and a precipitant solution, carrying out precipitation reaction to obtain a reacted material containing MHP, and carrying out thickening treatment to obtain MHP, in the precipitant solution, a precipitant comprises magnesium hydroxide and / or magnesium carbonate. According to the method, the composite oxidizing agent and the precipitating agent are compounded and subjected to precipitation reaction with the laterite-nickel ore liquid subjected to iron and aluminum removal, accurate regulation and control of the nickel-cobalt-manganese content proportion can be achieved by controlling the MHP crystallization process, and preparation of MHP with different manganese contents is met; and the problems of difficulty in MHP filter pressing, high water content, high impurity magnesium content and low production efficiency caused by seed crystal circulation due to local over-alkali during MHP precipitation are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and in particular to a method for preparing MHP based on an oxidation precipitation method. Background Art

[0002] MHP (nickel cobalt hydroxide) is an intermediate product in the hydrometallurgy of laterite nickel ore. That is, a high-pressure acid leaching process is usually adopted, with sulfuric acid as a leaching agent to dissolve metals such as nickel and cobalt from the laterite nickel ore. MHP is then obtained through processes such as impurity removal and precipitation. It is mainly used in the energy field and can be used as a key material for fuel cells, supercapacitors and battery positive electrodes. It can also be used to prepare metal salts such as nickel sulfate and cobalt sulfate, and has good application prospects.

[0003] At present, in the hydrometallurgical process of laterite nickel ore, the seed growth process is mostly used to prepare MHP products. In the preparation process, seeds are usually added in advance to provide a ready-made crystal surface for the ions to be precipitated, significantly reducing the nucleation energy barrier and increasing the precipitation reaction rate. However, it generally has the problem of low production efficiency. The reason is that after the precipitation process is completed, more than 90% of the bottom flow obtained will continue to return to the precipitation process as seeds, and each cycle can actually only grow 10% and takes a long time, resulting in a general reduction in production efficiency.

[0004] In response to the above-mentioned problem of low production efficiency, a direct precipitation reaction process of controlled crystallization precipitation with non-seed growth can effectively improve the problem of low production efficiency. The precipitation process in the existing technology mostly uses sodium hydroxide as a precipitant. Due to the strong alkalinity of sodium hydroxide, the process conditions need to be strictly controlled. Otherwise, it is easy to cause the problem of local over-alkalinity. Local over-alkalinity will lead to excessively high pH in the local aqueous solution, which in turn will cause multiple metal ions, such as nickel ions, cobalt ions, magnesium ions and manganese ions, to precipitate simultaneously. This makes the precipitated product contain more impurity ions, resulting in poor quality of the prepared MHP. In addition, the use of sodium hydroxide will also cause the generated precipitate particles to be fine, increasing the difficulty of sedimentation and filtration during solid-liquid separation, affecting production efficiency, and the high moisture content of the filter cake also increases the cost of subsequent transportation and processing. In addition, in the actual application process of MHP, different application fields have different requirements for the Mn content in MHP. How to accurately and flexibly control the Mn content in the obtained MHP in the preparation process is also one of the current problems.

[0005] Therefore, how to provide a method for preparing high-quality MHP with a simple preparation process and high production efficiency, while also being able to accurately and flexibly control the Mn content in the obtained MHP, has become a technical problem that needs to be solved urgently. Summary of the Invention

[0006] To address the above-mentioned technical problems, the present invention provides a method for preparing MHP based on an oxidation precipitation process. The present invention utilizes a composite oxidant and a precipitant to react with a laterite nickel ore solution after iron and aluminum removal. By controlling the MHP crystallization process, the ratio of nickel, cobalt, and manganese content can be precisely regulated, enabling the preparation of MHP with varying manganese contents. The composite oxidant rapidly forms some high-valent manganese oxides during the initial precipitation of the MHP, providing nucleation and crystallization sites for the MHP. This mitigates the explosive nucleation and agglomeration of numerous crystal nuclei caused by local over-alkalinity, thereby alleviating the difficult filtration, high water content, and high magnesium content of the impurity MHP. Furthermore, the composite oxidant provides greater flexibility in adjusting the manganese recovery rate, and the use of a precipitant comprising magnesium hydroxide and / or magnesium carbonate further mitigates the problem of local over-alkalinity.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing MHP based on an oxidative precipitation method, the method comprising the following steps:

[0009] The iron and aluminum-removed liquid of laterite nickel ore, a composite oxidant and a precipitant solution are mixed to carry out a precipitation reaction to obtain a reaction material containing MHP, which is then concentrated to obtain MHP;

[0010] In the precipitant solution, the precipitant includes magnesium hydroxide and / or magnesium carbonate.

[0011] The present invention adopts a composite oxidant and a precipitant to carry out a precipitation reaction with the iron and aluminum removed liquid of laterite nickel ore. By controlling the MHP crystallization process, the ratio of nickel, cobalt and manganese content can be precisely regulated to meet the preparation requirements of MHP with different manganese contents while taking into account the quality of the obtained MHP, namely, low impurity content and low water content. The composite oxidant can quickly form some high-valent manganese oxides in the early stage of MHP precipitation, providing nucleation and crystallization sites for MHP, improving the problems of explosive nucleation and agglomeration of a large number of crystal nuclei caused by local over-alkali, thereby alleviating the problems of difficult filtration, high water content and high impurity magnesium content of MHP. In addition, the composite oxidant will be more flexible in adjusting the manganese recovery rate, and the use of a precipitant including magnesium hydroxide and / or magnesium carbonate can further avoid the problem of local over-alkali.

[0012] As a preferred technical solution of the present invention, the composite oxidant includes a main oxidant and a secondary oxidant.

[0013] Preferably, the primary oxidant comprises a solid peroxide oxidant and / or a manganese-containing oxidant.

[0014] Preferably, the solid peroxide oxidant comprises Na2O2 and / or K2O2.

[0015] Preferably, the manganese-containing oxidant comprises K2MnO4 and / or KMnO4.

[0016] Preferably, the secondary oxidant comprises NaClO and / or H2O2.

[0017] The main oxidant of the present invention includes a solid peroxide oxidant and / or a manganese-containing oxidant. The sodium hydroxide and hydrogen peroxide generated by the reaction of peroxide (Na2O2 and / or K2O2) with water can provide OH while oxidizing divalent manganese ions. - To precipitate manganese and nickel-cobalt ions, a manganese-containing oxidant (K2MnO4 and / or KMnO4) is used. The advantage is that it can not only oxidize manganese ions, but also the manganese dioxide formed after its reduction can provide the crystal nuclei required for the precipitation of nickel-cobalt ions.

[0018] As a preferred technical solution of the present invention, the molar amount of the oxidant required to oxidize divalent manganese to trivalent or higher manganese in the laterite nickel ore after iron and aluminum removal is taken as the required theoretical amount, and the molar ratio of the composite oxidant to the required theoretical amount is (0.0001-1):1, for example, 0.0001:1, 0.0002:1, 0.0003:1, 0.0004:1, 0.0005:1, 0.0006:1, 0.0007:1, 0.0008:1, 0.0009:1, 0.001:1, 0.005:1, 0.01:1, 0.5:1 or 1:1, etc., preferably (0.0001-0.001):1.

[0019] In the present invention, the Mn content in the resulting MHP can be precisely and flexibly controlled by adjusting the molar ratio of the composite oxidant to the required theoretical amount to (0.0001-0.001):1. Excessive composite oxidant content significantly increases the moisture content of the resulting MHP, hindering subsequent storage and transportation.

[0020] Preferably, the method for preparing the precipitant solution comprises: mixing an alkaline solution and a solution containing magnesium sulfate, and performing a base conversion reaction to obtain the precipitant solution.

[0021] As a preferred technical solution of the present invention, in the alkaline solution, the alkaline substance includes any one of sodium carbonate, ammonium carbonate or sodium hydroxide, or a combination of at least two of them.

[0022] Preferably, the concentration of the alkaline solution is 0.5wt% to 30wt%, for example, 0.5wt%, 1wt%, 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 28wt% or 30wt%, etc.

[0023] Preferably, the magnesium sulfate-containing solution comprises the liquid after manganese precipitation of laterite nickel ore.

[0024] Preferably, the concentration of magnesium ions in the magnesium sulfate solution is 4 g / L to 6 g / L, for example, 4 g / L, 5 g / L or 6 g / L.

[0025] In the present invention, an alkaline solution and a magnesium sulfate solution are mixed to carry out an alkali-transfer reaction to obtain the precipitant solution, which has the following advantages: first, the preparation cost is saved. Compared with directly preparing a precipitant solution containing magnesium hydroxide and / or magnesium carbonate, the alkali-transfer reaction uses the liquid after manganese precipitation of laterite nickel ore as the magnesium sulfate solution, which can further reduce the cost, and the liquid after manganese precipitation of laterite nickel ore is reused, which is also convenient for further improving the utilization rate of raw materials; second, the magnesium hydroxide and / or magnesium carbonate generated by the alkali-transfer reaction is used as a precipitant, and in the later precipitation reaction process, the precipitation effect is relatively better, and the obtained MHP crystals are better and the quality is higher.

[0026] As a preferred technical solution of the present invention, in the alkali-transfer reaction, the amount of the alkaline substance added is 10 wt% to 100 wt% of the theoretical amount required to precipitate all the magnesium in the magnesium sulfate-containing solution, for example, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt% or 100 wt%, etc., preferably 50 wt% to 60 wt%.

[0027] In the present invention, by further regulating the total amount of alkaline substance added to 50wt% to 60wt% of the theoretical amount required to completely precipitate the magnesium in the magnesium sulfate solution, the precipitant content in the resulting precipitant solution is regulated within an optimal range, facilitating the subsequent precipitation reaction and resulting in better MHP performance. If the alkaline substance content is too low, the alkaline conversion reaction will be incomplete, reducing the precipitating components in the resulting precipitant solution, thereby affecting the subsequent precipitation reaction; if the alkaline substance content is too high, the resulting precipitant solution will contain incompletely reacted alkaline substances, resulting in an increase in the precipitating components and enhanced alkalinity. During the subsequent precipitation process, local over-alkalinity reactions may occur, thereby affecting the moisture content of the resulting MHP.

[0028] Preferably, the temperature of the alkali transfer reaction is 30°C to 60°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C.

[0029] Preferably, the alkali transfer reaction time is 2 min to 10 min, for example, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min.

[0030] Preferably, the stirring speed of the alkali transfer reaction is 1 r / min to 5 r / min, for example, 1 r / min, 2 r / min, 3 r / min, 4 r / min or 5 r / min.

[0031] Preferably, the pressure of the alkali-transfer reaction is normal pressure.

[0032] The normal pressure mentioned in the present invention refers to standard atmospheric pressure, which is about 100 kPa.

[0033] As a preferred technical solution of the present invention, the liquid after iron and aluminum removal from the laterite nickel ore includes nickel, cobalt, manganese and magnesium.

[0034] Preferably, the concentration of nickel in the laterite nickel ore liquid after iron and aluminum removal is 2 g / L to 6 g / L, for example, 2 g / L, 3 g / L, 4 g / L, 5 g / L or 6 g / L.

[0035] Preferably, the concentration of cobalt in the laterite nickel ore liquid after iron and aluminum removal is 0.1 g / L to 0.6 g / L, for example, 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L or 0.6 g / L.

[0036] Preferably, the concentration of manganese in the laterite nickel ore liquid after iron and aluminum removal is 1 g / L to 6 g / L, for example, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L or 6 g / L.

[0037] Preferably, the concentration of magnesium in the laterite nickel ore liquid after iron and aluminum removal is 4 g / L to 12 g / L, for example, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L or 12 g / L.

[0038] As a preferred technical solution of the present invention, the mixed raw materials also include an auxiliary precipitant.

[0039] Preferably, the auxiliary precipitant includes any one of EDTA, ammonia water or a surfactant, or a combination of at least two of them.

[0040] Preferably, the surfactant includes any one of cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate or polyethylene glycol, or a combination of at least two thereof.

[0041] As a preferred technical solution of the present invention, the pH of the precipitation reaction is 6.8-7.5, for example, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4 or 7.5.

[0042] Preferably, the precipitation reaction temperature is 30°C to 85°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C or 85°C.

[0043] Preferably, the precipitation reaction time is 1 h to 8 h, for example, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, etc., preferably 2 h to 6 h.

[0044] As a preferred technical solution of the present invention, after the thickening treatment, the process further comprises a step of performing solid-liquid separation on the obtained underflow MHP slurry to obtain MHP.

[0045] Preferably, the solid-liquid separation includes a filtration process.

[0046] Preferably, the filtration treatment comprises vacuum filtration or filter press filtration.

[0047] As a preferred technical solution of the present invention, the method for preparing MHP based on the oxidation precipitation method comprises the following steps:

[0048] (1) mixing an alkaline solution and a magnesium sulfate solution, stirring and mixing at 1 rpm to 5 rpm and 30° C. to 60° C. for 2 to 10 minutes to perform a base conversion reaction to obtain a precipitant solution, wherein the precipitant comprises magnesium hydroxide and / or magnesium carbonate;

[0049] The concentration of the alkaline solution is 0.5 wt% to 30 wt%; the magnesium sulfate-containing solution comprises a laterite nickel ore manganese precipitation solution having a magnesium ion concentration of 4 g / L to 6 g / L; in the alkali conversion reaction, the amount of the alkaline substance added is 10 wt% to 100 wt% of the theoretical amount required to completely precipitate the magnesium in the magnesium sulfate-containing solution;

[0050] (2) mixing the laterite nickel ore after iron and aluminum removal, a composite oxidant, a precipitant solution, and an auxiliary precipitant, and performing a precipitation reaction at 30° C. to 85° C. and a pH of 6.8 to 7.5 for 1 to 8 hours to obtain a reaction material containing MHP, and performing a thickening treatment on the obtained underflow MHP slurry to obtain MHP;

[0051] The molar amount of the oxidant required to oxidize divalent manganese to trivalent or higher manganese in the laterite nickel ore after iron and aluminum removal is taken as the required theoretical amount, and the molar ratio of the composite oxidant to the required theoretical amount is (0.0001-0.001):1; the laterite nickel ore after iron and aluminum removal liquid contains nickel with a concentration of 2g / L-6g / L, cobalt with a concentration of 0.1g / L-0.6g / L, manganese with a concentration of 1g / L-6g / L, and magnesium with a concentration of 4g / L-12g / L.

[0052] Compared with the prior art, the present invention has at least the following beneficial effects:

[0053] 1) The present invention adopts a direct precipitation reaction process and can effectively improve the quality of MHP by controlling the MHP crystallization process, that is, low impurity content and low water content.

[0054] 2) The composite oxidant of the present invention can quickly form some high-valent manganese oxides in the early stage of MHP precipitation, providing nucleation and crystallization sites for MHP, improving the problems of explosive nucleation and agglomeration of a large number of crystal nuclei caused by local over-alkali, thereby improving the problems of difficult filtration, high water content and high impurity magnesium content of MHP. In addition, the composite oxidant will be more flexible in adjusting the manganese recovery rate, and the use of a precipitant including magnesium hydroxide and / or magnesium carbonate can further avoid the problem of local over-alkali. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The present invention provides a flow chart of a method for preparing MHP based on an oxidative precipitation method.

[0056] Figure 2 This is a flow chart of the method for preparing MHP based on the oxidation precipitation method provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0057] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0058] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0059] Figure 1 The flow chart of the method for preparing MHP based on the oxidation precipitation method provided by the present invention is shown, and the method comprises the following steps:

[0060] The iron-aluminum-removed liquid of laterite nickel ore, a composite oxidant and a precipitant solution are mixed to carry out precipitation reaction to obtain a reaction material containing MHP, which is then concentrated to obtain MHP.

[0061] The main components of the laterite nickel ore liquid after iron and aluminum removal used in the following examples and comparative examples include the following components: Ni is 3.87 g / L, Co is 0.41 g / L, Mn is 2.73 g / L and Mg is 6.44 g / L.

[0062] The magnesium sulfate solution used in the following examples and comparative examples is the solution after manganese precipitation in laterite nickel ore, wherein the magnesium ion concentration is 5 g / L.

[0063] Example 1

[0064] This embodiment provides a method for preparing MHP based on oxidation precipitation method, as shown in the flow chart. Figure 2 As shown, the method includes the following steps:

[0065] (1) Sodium carbonate and sodium hydroxide (mass ratio 1:1) are dissolved in deionized water to prepare an alkaline solution with a concentration of 15 wt%, and the alkaline solution is mixed with a laterite nickel ore manganese precipitation solution at 50° C. and a speed of 2 r / min for 5 min under normal pressure to perform an alkali conversion reaction to obtain a precipitant solution containing magnesium hydroxide and magnesium carbonate, wherein the total amount of sodium carbonate and sodium hydroxide added is regulated to be 55 wt% of the theoretical amount required to completely precipitate magnesium in the laterite nickel ore manganese precipitation solution;

[0066] (2) The de-ironized and de-aluminized laterite nickel ore solution, Na2O2, KMnO4, NaClO, a precipitant solution containing magnesium hydroxide and magnesium carbonate, and aqueous ammonia were mixed and subjected to precipitation reaction at 55°C and pH 7 for 4 hours to obtain a reaction material containing MHP. The resulting underflow MHP slurry was subjected to filter pressing after concentration treatment to obtain MHP. The molar amount of the oxidant required to oxidize divalent manganese in the de-ironized and de-aluminized laterite nickel ore solution to trivalent or higher manganese was taken as the required theoretical amount. The molar ratio of the composite oxidant (Na2O2, KMnO4, and NaClO) to the required theoretical amount was 0.0005:1, and the mass ratio of Na2O2, KMnO4, and NaClO was 1:1:0.5.

[0067] Example 2

[0068] This embodiment provides a method for preparing MHP based on an oxidative precipitation method, the method comprising the following steps:

[0069] (1) ammonium carbonate and sodium hydroxide (mass ratio 1:1) are dissolved in deionized water to prepare an alkaline solution with a concentration of 0.5 wt %, and the alkaline solution is mixed with a laterite nickel ore manganese precipitation solution at 30° C. and a speed of 1 r / min for 10 min under normal pressure to perform an alkali conversion reaction to obtain a precipitant solution containing magnesium hydroxide and magnesium carbonate, wherein the total amount of sodium carbonate and sodium hydroxide added is regulated to be 50 wt % of the theoretical amount required to completely precipitate magnesium in the laterite nickel ore manganese precipitation solution;

[0070] (2) The de-ironized and de-aluminized laterite nickel ore solution, K2O2, K2MnO4, NaClO, a precipitant solution containing magnesium hydroxide and magnesium carbonate, and EDTA were mixed and subjected to precipitation reaction at 40°C and pH 6.8 for 6 hours to obtain a reaction material containing MHP. After thickening, the obtained underflow MHP slurry was filter-filtered to obtain MHP. The molar amount of the oxidant required to oxidize divalent manganese in the de-ironized and de-aluminized laterite nickel ore solution to trivalent or higher manganese was taken as the required theoretical amount, the molar ratio of the composite oxidant (K2O2, K2MnO4, and NaClO) to the required theoretical amount was 0.0001:1, and the mass ratio of K2O2, K2MnO4, and NaClO was 1:1:0.5.

[0071] Example 3

[0072] This embodiment provides a method for preparing MHP based on an oxidative precipitation method, the method comprising the following steps:

[0073] (1) dissolving sodium hydroxide in deionized water to prepare an alkaline solution with a concentration of 30 wt %, mixing the alkaline solution with a solution obtained after manganese precipitation from laterite nickel ore at 60° C. and 5 rpm for 2 min under normal pressure to perform an alkali conversion reaction to obtain a solution containing a magnesium hydroxide precipitant, wherein the amount of sodium hydroxide added is regulated to be 60 wt % of the theoretical amount required to completely precipitate magnesium in the solution obtained after manganese precipitation from laterite nickel ore;

[0074] (2) The de-ironized and de-aluminized laterite nickel ore solution, Na2O2, K2MnO4, NaClO, a magnesium hydroxide precipitant solution and ammonia water were mixed and subjected to precipitation reaction at 70°C and pH 7.2 for 2 hours to obtain a reaction material containing MHP. After thickening treatment, the obtained underflow MHP slurry was filter-filtered to obtain MHP, wherein the molar amount of the oxidant required for oxidizing divalent manganese in the de-ironized and de-aluminized laterite nickel ore solution to trivalent or higher manganese was taken as the required theoretical amount, the molar ratio of the composite oxidant (Na2O2, K2MnO4 and NaClO) to the required theoretical amount was 0.001:1, and the mass ratio of Na2O2, K2MnO4 and NaClO was 1:1:0.5.

[0075] Example 4

[0076] This example provides a method for preparing MHP based on an oxidative precipitation method. The difference between the method and Example 1 is that the total amount of sodium carbonate and sodium hydroxide added is 10 wt % of the theoretical amount required to completely precipitate magnesium in the liquid after manganese precipitation from laterite nickel ore. The remaining preparation methods and parameters are consistent with Example 1.

[0077] Example 5

[0078] This example provides a method for preparing MHP based on an oxidative precipitation method. The difference between the method and Example 1 is that the total amount of sodium carbonate and sodium hydroxide added is 100 wt % of the theoretical amount required to completely precipitate magnesium in the liquid after manganese precipitation from laterite nickel ore. The remaining preparation methods and parameters are consistent with Example 1.

[0079] Example 6

[0080] This example provides a method for preparing MHP based on an oxidative precipitation method. The method differs from Example 1 in that the alkali conversion reaction is omitted and a precipitant solution containing magnesium hydroxide and magnesium carbonate of equal concentrations is directly used. The addition of an aqueous ammonia solution is omitted in step (2). The remaining preparation methods and parameters are consistent with those in Example 1.

[0081] Example 7

[0082] This example provides a method for preparing MHP based on an oxidation precipitation method. The difference between the method and Example 1 is that the molar amount of the oxidant required to oxidize divalent manganese in the laterite nickel ore after iron and aluminum removal to trivalent or higher manganese is used as the required theoretical amount, and the molar ratio of the composite oxidant (Na2O2, KMnO4 and NaClO) to the required theoretical amount is 0.0015:1. The remaining preparation methods and parameters are consistent with Example 1.

[0083] Examples 8 to 10

[0084] Examples 8 to 10 provide a method for preparing MHP based on an oxidative precipitation method. The difference between the method and Example 1 is that the molar amount of the oxidant required to oxidize divalent manganese in the laterite nickel ore after iron and aluminum removal to trivalent or higher manganese is used as the required theoretical amount, and the molar ratio of the composite oxidant (Na2O2, KMnO4 and NaClO) to the required theoretical amount is 0.0003:1, 0.0008:1 and 0.001:1, respectively. The rest of the preparation method and parameters are consistent with Example 1.

[0085] Comparative Example 1

[0086] This comparative example provides a method for preparing MHP based on an oxidative precipitation method. The method differs from Example 1 in that a single oxidant, NaClO, is used as the oxidant, and the molar ratio of the oxidant (NaClO) to the required theoretical amount is 0.0005:1. The remaining preparation methods and parameters are consistent with Example 1.

[0087] Comparative Example 2

[0088] This comparative example provides a method for preparing MHP based on an oxidative precipitation method. The method differs from Example 1 in that Na2O2, KMnO4, and NaClO are omitted, and in step (2), the laterite nickel ore liquid after iron and aluminum removal, the precipitant solution containing magnesium hydroxide and magnesium carbonate, and ammonia water are directly mixed. The remaining preparation methods and parameters are consistent with those in Example 1.

[0089] The components and moisture content of the MHP obtained in Examples 1 to 10 and Comparative Examples 1 to 2 were tested, respectively. The specific contents are shown in Table 1.

[0090] Table 1

[0091]

[0092]

[0093] The test results show that:

[0094] (1) It can be seen from Examples 1 to 6 that the present invention uses a composite oxidant and a precipitant to carry out a precipitation reaction with the laterite nickel ore after iron and aluminum removal, and controls the MHP crystallization process to achieve precise regulation of the nickel, cobalt and manganese content ratio, thereby meeting the preparation of MHP with different manganese contents and taking into account the quality of the obtained MHP, namely, low impurity content and low water content; wherein, the composite oxidant and precipitant system will be more flexible in adjusting the manganese recovery rate, and the selection of the precipitant can also avoid the problem of a large amount of impurities in the MHP system caused by local over-alkali.

[0095] Specifically, the obtained MHP has a Mn content of 5.21wt% to 9.49wt%, a Ni content of 36.72wt% to 41.43wt%, a Co content of 3.45wt% to 4.46wt%, and a Mg content of 1.59wt% to 2.48wt%. The Ni, Co, and Mn contents are all within a reasonable range, and the content of the impurity Mg is relatively low, meeting the use requirements of MHP. The moisture content is also between 43.15% and 47.32%, meeting the MHP product standards.

[0096] (2) It can be seen from Examples 1 and 4 to 5 that the present invention further regulates the total amount of alkaline substance added to 50 wt% to 60 wt% of the theoretical amount required to precipitate all magnesium in the magnesium sulfate solution, thereby regulating the content of the precipitant in the obtained precipitant solution within a preferred range, facilitating the subsequent precipitation reaction, and resulting in better performance of the obtained MHP.

[0097] (3) It can be seen from Examples 1 and 7 that the present invention can accurately and flexibly control the Mn content in the obtained MHP by further adjusting the molar ratio of the composite oxidant to the required theoretical amount to (0.0001-0.001):1 after compounding with the precipitant, while taking into account the high quality of the obtained MHP.

[0098] (4) Taking Example 1 and Examples 8 to 10 as examples, the Mn content in the MHP obtained in these four examples was evaluated. The Mn contents in Example 1 and Examples 8 to 10 were 7.37 wt%, 6.18 wt%, 7.94 wt% and 8.89 wt%, respectively, indicating that the method for preparing MHP provided by the present invention can not only obtain an MHP product with a low water content, but also can adjust the Mn content in the MHP product by adding the amount of the composite oxidant, thereby being able to adapt to different product requirements.

[0099] (5) It can be seen from Example 1 and Comparative Example 1 that the present invention, by adopting a composite oxidant, can quickly form some high-valent manganese oxides in the early stage of MHP precipitation, providing nucleation and crystallization sites for MHP, improving the problems of explosive nucleation and agglomeration of a large number of crystal nuclei caused by local over-alkali, thereby improving the problems of difficult filtration, high water content and high impurity magnesium content of MHP. If a single oxidant is used, it is impossible to better control the quality of the obtained MHP.

[0100] (6) It can be seen from Example 1 and Comparative Example 2 that when no oxidant is used and the precipitant is not compounded, it is impossible to precipitate Mn and it is also impossible to control the Mn content in the obtained MHP.

[0101] In summary, the present invention adopts a composite oxidant and a precipitant to carry out a precipitation reaction with the laterite nickel ore liquid after iron and aluminum removal. By controlling the MHP crystallization process, the ratio of nickel, cobalt and manganese content can be precisely controlled to meet the preparation of MHP with different manganese contents. The composite oxidant can quickly form some high-valent manganese oxides in the early stage of MHP precipitation, providing nucleation and crystallization sites for MHP, improving the problems of explosive nucleation and agglomeration of a large number of crystal nuclei caused by local over-alkali, thereby improving the problems of difficult filtration, high water content and high impurity magnesium content of MHP. In addition, the composite oxidant will be more flexible in adjusting the recovery rate of manganese, and the use of a precipitant including magnesium hydroxide and / or magnesium carbonate can further avoid the problem of local over-alkali.

[0102] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing MHP based on oxidation precipitation method, characterized in that: The method comprises the following steps: The iron and aluminum-removed liquid of laterite nickel ore, a composite oxidant and a precipitant solution are mixed to carry out a precipitation reaction to obtain a reaction material containing MHP, which is then concentrated to obtain MHP; In the precipitant solution, the precipitant includes magnesium hydroxide and / or magnesium carbonate.

2. The method according to claim 1, characterized in that The composite oxidant includes a main oxidant and a secondary oxidant; Preferably, the primary oxidant comprises a solid peroxide oxidant and / or a manganese-containing oxidant; Preferably, the solid peroxide oxidant comprises Na2O2 and / or K2O2; Preferably, the manganese-containing oxidant comprises K2MnO4 and / or KMnO4; Preferably, the secondary oxidant comprises NaClO and / or H2O2.

3. The method according to claim 1 or 2, characterized in that The molar amount of the oxidant required to oxidize divalent manganese to trivalent or higher manganese in the laterite nickel ore after iron and aluminum removal is the required theoretical amount, and the molar ratio of the composite oxidant to the required theoretical amount is (0.0001-1):1, preferably (0.0001-0.001):

1.

4. The method according to any one of claims 1 to 3, characterized in that The preparation method of the precipitant solution comprises: mixing an alkaline solution and a solution containing magnesium sulfate, and performing a base conversion reaction to obtain the precipitant solution.

5. The method according to claim 4, characterized in that In the alkaline solution, the alkaline substance includes any one of sodium carbonate, ammonium carbonate or sodium hydroxide, or a combination of at least two thereof; Preferably, the concentration of the alkaline solution is 0.5wt% to 30wt%; Preferably, the magnesium sulfate-containing solution comprises the liquid after manganese precipitation of laterite nickel ore.

6. The method according to claim 5, characterized in that In the alkali conversion reaction, the amount of the alkaline substance added is 10 wt% to 100 wt% of the theoretical amount required to precipitate all the magnesium in the magnesium sulfate solution, preferably 50 wt% to 60 wt%; Preferably, the temperature of the alkali conversion reaction is 30°C to 60°C; Preferably, the time of the alkali transfer reaction is 2 min to 10 min; Preferably, the stirring speed of the alkali transfer reaction is 1 r / min to 5 r / min.

7. The method according to any one of claims 1 to 6, characterized in that The laterite nickel ore liquid after iron and aluminum removal contains nickel, cobalt, manganese and magnesium; Preferably, the concentration of nickel in the laterite nickel ore liquid after iron and aluminum removal is 2 g / L to 6 g / L; Preferably, the concentration of cobalt in the laterite nickel ore liquid after iron and aluminum removal is 0.1 g / L to 0.6 g / L; Preferably, the concentration of manganese in the laterite nickel ore liquid after iron and aluminum removal is 1 g / L to 6 g / L; Preferably, the concentration of magnesium in the laterite nickel ore liquid after iron and aluminum removal is 4 g / L to 12 g / L.

8. The method according to any one of claims 1 to 7, characterized in that The mixed raw materials also include an auxiliary precipitant; Preferably, the auxiliary precipitant includes any one of EDTA, ammonia water or a surfactant, or a combination of at least two of them.

9. The method according to any one of claims 1 to 8, characterized in that The pH of the precipitation reaction is 6.8 to 7.5; Preferably, the temperature of the precipitation reaction is 30°C to 85°C; Preferably, the precipitation reaction time is 1 h to 8 h, preferably 2 h to 6 h.

10. The method according to any one of claims 1 to 9, characterized in that After the thickening treatment, the method further includes a step of performing solid-liquid separation on the obtained underflow MHP slurry to obtain MHP.

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