A method for preparing MHP from laterite nickel ore by using active magnesium oxide and recycling tail water

Abstract

The application discloses a method for preparing MHP from laterite nickel ore by using active magnesium oxide and recycling tail water, which comprises the following steps: treating the laterite nickel ore by high-pressure acid leaching, obtaining a solution to be refined after removing iron and aluminum, adding a certain amount of active magnesium oxide and fully reacting; concentrating the mixed solution after the reaction to obtain clear liquid and solid-containing slurry; filtering and washing the solid-containing slurry to obtain MHP; collecting the clear liquid, filtrate and washing liquid, adding a certain amount of tail water treatment reagent, filtering after the reaction, recycling the filtrate as acid leaching water or washing water, and separating by-product calcium sulfate and magnesium hydroxide from magnesium and calcium solid residues after tail water treatment; calcining the magnesium hydroxide to obtain active magnesium oxide, which is further used for the preparation of MHP. The method for preparing MHP from laterite nickel ore by using active magnesium oxide and recycling tail water is simple in process, low in cost, can significantly improve production efficiency and realize the recycling of magnesium resources and water resources.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, specifically a method for preparing MHP from laterite nickel ore by using active magnesium oxide and recycling tail water. Background Art

[0002] In the face of climate change, countries around the world are actively promoting the low-carbon transformation of energy. The new energy vehicle industry has also developed rapidly. Nickel (Ni), cobalt (Co), and lithium (Li), as key raw materials for power batteries, are also experiencing a rapid increase in demand.

[0003] At present, the main process for preparing nickel is the wet refining of laterite nickel ore. In a high temperature and high pressure environment, laterite nickel ore is selectively leached with sulfuric acid to extract Ni, Co, Mg, Mn, Cu, etc. The slurry is neutralized, washed, and impurities are removed before adding a precipitant to produce the intermediate product MHP (nickel cobalt hydroxide). At present, the precipitation process mostly uses sodium hydroxide as a precipitant. Although this method is simple, the consumption of the precipitant sodium hydroxide is large, and due to the strong alkalinity of sodium hydroxide, the generated precipitate particles are small, which increases the difficulty of sedimentation and filtration during solid-liquid separation, affecting production efficiency, and the filter cake has a high moisture content, which increases the cost of later transportation and processing. Using sodium hydroxide as a precipitant, while preparing MHP, Na + Ions, including Na + Direct discharge of ion tail water will pollute land and water resources, and the cost and difficulty of tail water treatment are high, which increases production costs. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a wet refining method for laterite nickel ore in which the precipitate is easy to settle and filter and the tail water can be recycled.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water comprises the following steps:

[0007] (1) high-pressure acid leaching of laterite nickel ore to obtain a solution to be refined;

[0008] (2) adding active magnesium oxide to the solution to be extracted in step (1) to fully react;

[0009] (3) the mixed solution after the reaction is concentrated to obtain a clear liquid and a solid slurry;

[0010] (4) filtering the solid slurry and washing it with water to obtain MHP;

[0011] (5) using a tail water treatment reagent to treat the tail water consisting of the clear liquid in step (3), the filtrate in step (4) and the water washing liquid, wherein the tail water treatment reagent is quicklime, modified quicklime or slaked lime, which reacts with the tail water to obtain a solid slag containing calcium and magnesium, and the solid slag containing calcium and magnesium is separated by gravity separation to obtain calcium sulfate and magnesium hydroxide, and the magnesium hydroxide is calcined to prepare active magnesium oxide for use in step (2), thereby realizing the circulation of magnesium resources.

[0012] In the above method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water, in step (1): the acid used for high-pressure acid leaching of laterite nickel ore is sulfuric acid solution.

[0013] In the above method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water, in step (2): the magnesium oxide content in the activated magnesium oxide is 88-99.8 wt.%, preferably 92.5-95.5 wt.%; and the citric acid activity value of the activated magnesium oxide is 10-100 s, preferably 10-40 s.

[0014] The above method for preparing MHP from laterite nickel ore using active magnesium oxide and recycling tail water comprises the following steps: in step (2): the amount of active magnesium oxide added is the amount of Ni in the solution to be extracted in step (1); 2+ and Co 2+ 0.5 to 1.0 times, preferably 0.6 to 0.75 times the total mass.

[0015] In the above method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water, in step (3): the mixed solution after the reaction is concentrated using a thickener for natural sedimentation, and the clear liquid and the solid slurry are obtained by layering.

[0016] In the above method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water, in step (4) and step (5): filtration is performed by plate and frame filter pressing, vacuum filtration or centrifugal filtration.

[0017] The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water, in step (5): the tail water treatment reagent is added by dry powder addition or slurry addition, preferably slurry addition; the tail water treatment reagent slurry concentration is greater than or equal to 0wt.% and less than or equal to 70wt.%, preferably 30wt.% to 55wt.%; the slurry is mechanically stirred, and the stirring rate is 100 to 500r / min, preferably 200 to 300r / min; the slurry mixing time is 3 to 300min, preferably 5 to 10min; the amount of tail water treatment reagent added is 0.85 to 2.50 times the total mass of Mg in the tail water to be treated, calculated as Ca mass, preferably 1.50 to 1.84 times; the tail water treatment temperature is 10 to 60°C, preferably 20 to 40°C, and the reaction time between the tail water and the tail water treatment reagent is 10 to 180min, preferably 30 to 60min.

[0018] In the above method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water, the modified quicklime preparation method in step (5) is as follows:

[0019] (a) Adding aminosilane coupling agent and quicklime to ethanol and stirring to react for 0.5 to 2 hours;

[0020] (b) adding carboxymethyl-β-cyclodextrin to water, stirring and mixing until uniform, and then adding to the mixture obtained in step (a), stirring and reacting for 1 to 3 hours;

[0021] (c) adding magnesium hydroxide seed particles to the mixture obtained in step (b), stirring and heating to 60-80° C. and maintaining stirring for 2-5 hours, filtering after the reaction is completed, and drying the filter residue to obtain modified calcium oxide.

[0022] The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water comprises the following steps: in step (a), the volume ratio of an aminosilane coupling agent to ethanol is 0.01 to 0.1:1, and the mass-to-volume ratio of quicklime to the aminosilane coupling agent is (100 to 200):1 g / mL; in step (b), the mass-to-volume ratio of carboxymethyl-β-cyclodextrin to water is (300 to 400):1 g / L, and the amount of carboxymethyl-β-cyclodextrin used is 1.1 to 1.5 times the amount of the aminosilane coupling agent; and in step (c), the amount of magnesium hydroxide seed particles added is 5 to 10% of the mass of the carboxymethyl-β-cyclodextrin.

[0023] The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water comprises the following steps: in step (a), the volume ratio of aminosilane coupling agent to ethanol is 0.05:1, and the mass volume ratio of quicklime to aminosilane coupling agent is 150:1 g / mL; in step (b), the mass volume ratio of carboxymethyl-β-cyclodextrin to water is 350:1 g / L, and the amount of carboxymethyl-β-cyclodextrin is 1.2 times the amount of aminosilane coupling agent; and in step (c), the amount of magnesium hydroxide seed particles added is 6% of the mass of carboxymethyl-β-cyclodextrin.

[0024] The separation of solid slag containing calcium and magnesium utilizes the density difference between magnesium hydroxide and calcium sulfate and adopts gravity separation method to separate the two.

[0025] The chemical reactions involved in the present invention are mainly as follows:

[0026] Active magnesium oxide is added to the solution, and the magnesium oxide hydrolyzes:

[0027] MgO+H2O→Mg(OH)2↓

[0028] Magnesium hydroxide ionizes in aqueous solution:

[0029] Mg(OH)2→Mg 2+ +2OH -

[0030] OH ionized by magnesium hydroxide - The ions combine with nickel ions (or cobalt ions) in the solution to form nickel hydroxide precipitates (or cobalt hydroxide precipitates):

[0031] Mg(OH)2+NiSO4→Ni(OH)2↓+MgSO4

[0032] Mg(OH)2+CoSO4→Co(OH)2↓+MgSO4

[0033] When activated magnesium oxide and laterite nickel ore acid leaching solution generate nickel hydroxide precipitation, the tail water is a solution containing MgSO4. To treat the tail water, one or more of quicklime or slaked lime is added:

[0034] CaO+H2O→Ca(OH)2↓

[0035] Ca(OH)2+MgSO4→Mg(OH)2↓+CaSO4↓

[0036] After the tail water is treated, the solid slag containing calcium and magnesium is separated to obtain by-products of calcium sulfate and magnesium hydroxide, and the magnesium hydroxide is calcined to prepare active magnesium oxide.

[0037]

[0038] The technical solution of the present invention achieves the following beneficial technical effects:

[0039] (1) In the present invention, MHP is prepared from laterite nickel ore using activated magnesium oxide, and the amount added is only Ni in the laterite nickel ore acid leaching solution. 2+ 0.5 to 1.0 times the total amount of ions, due to the OH that can be ionized per unit mole of active magnesium oxide - The traditional NaOH precipitant ionizes OH - ions, so the unit consumption is small and the cost is low.

[0040] (2) The addition of active magnesium oxide produces a weaker alkaline solution, and the nickel hydroxide precipitate produced during use is easy to settle and filter, effectively avoiding the current problems of sedimentation and filtration difficulties during the use of NaOH precipitant, and significantly improving production efficiency.

[0041] (3) When active magnesium oxide is added to prepare MHP from laterite nickel ore, the tail water produced is mainly a solution containing MgSO4. After the introduction of quicklime, modified quicklime or slaked lime, the filtrate can be used as acid leaching water or MHP washing water after filtration. Compared with the tail water containing Na2SO4 produced by NaOH precipitant, the treatment method is efficient, simple and low-cost. The treated tail water can be recycled to achieve zero water discharge.

[0042] (4) The calcium and magnesium-containing solid slag obtained after tail water treatment is separated by gravity separation to obtain by-products of calcium sulfate and magnesium hydroxide. The magnesium hydroxide is calcined to prepare active magnesium oxide, which is then used in the sedimentation process of MHP, realizing the recycling of magnesium resources and reducing production costs.

[0043] (5) The process of the present invention is simple, low-cost, and MHP is easy to settle and filter, which can significantly improve production efficiency. In addition, the tail water treatment is simple and efficient. After the tail water treatment, the filtrate is recycled to achieve zero water discharge. The magnesium hydroxide obtained after solid slag separation is calcined to generate highly active magnesium oxide, which is used as a precipitant, thereby achieving the recycling of magnesium resources.

[0044] (6) First, aminosilane coupling agent is used to modify calcium oxide to increase the hydrophobicity of calcium oxide and reduce the hydrophilicity of calcium oxide, thereby delaying the reaction of calcium oxide with water, and avoiding the formation of more calcium hydroxide precipitates while generating magnesium hydroxide precipitates, which collide with the magnesium hydroxide precipitates and agglomerate, making it difficult to precipitate, filter and wash the magnesium hydroxide.

[0045] (7) In order to quickly generate larger particles of magnesium hydroxide that are easy to settle, filter and wash, and to avoid the poor dispersibility of aminosilane coupling agent modified calcium oxide in tail water; the salt-forming reaction between the carboxyl group of carboxymethyl-β-cyclodextrin and the amino group of aminosilane coupling agent is used to make the aminosilane coupling agent modified calcium oxide and carboxymethyl-β-cyclodextrin compounded together, and then the magnesium hydroxide seed particles are combined with the hydroxyl group of carboxymethyl-β-cyclodextrin through hydrogen bonds, so that the magnesium hydroxide seed particles and calcium oxide are organically compounded. The magnesium hydroxide seed particles provide crystal nuclei for the magnesium hydroxide generated by the reaction. The calcium hydroxide generated by the slow reaction of calcium oxide with water is dissolved in water and then reacts with magnesium ions in the tail water to form magnesium hydroxide precipitates that can quickly adhere to the surface of the magnesium hydroxide seed particles, so that the newly generated finer particles of magnesium hydroxide are converted into larger particles of magnesium hydroxide; solve the problems of small magnesium hydroxide particle size, easy agglomeration of crystals, and difficulty in settling, filtering and washing in the magnesium hydroxide production process using the calcium hydroxide method. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The present invention is a process flow diagram of a method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0048] Example 1

[0049] Refer to Figure 1 As shown in Table 1, the chemical composition of the leachate after high-pressure leaching of laterite nickel ore with sulfuric acid solution and removal of iron and aluminum is shown in Table 1.

[0050] Table 1. Chemical composition of laterite nickel ore acid leaching solution Unit: g / L

[0051]

[0052] 5L of the leachate was placed in a beaker and placed in a constant-temperature water bath with stirring. 13.09g (0.6 times the total mass of Ni and Co) of activated magnesium oxide with a MgO content of 93.5wt.% and a citric acid activity of 22s was added and stirred thoroughly. After the reaction was complete, the solution was poured into a test thickener. The solid-liquid separation was observed and the settling time was recorded to obtain a clear liquid A and a solid-containing slurry. The solid-containing slurry was vacuum filtered, the filter cake was washed with water and filtered again, and the two filtrates, B, and clear liquid A, were mixed and treated as tail water to obtain the filter cake, which is MHP. A comparison of the effects of activated magnesium oxide and sodium hydroxide as precipitants under the same conditions is shown in Table 2.

[0053] Table 2. Comparison of the effects of activated magnesium oxide and sodium hydroxide as precipitants

[0054]

[0055] As shown in Table 2, the method of preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water of the present invention has a slightly higher Ni content in MHP than that of conventional sodium hydroxide as a precipitant, a lower filter cake moisture content, and a much higher sedimentation rate than sodium hydroxide, thus having good sedimentation and filtration rates. In addition, the unit consumption of the precipitant is 766 kg, which is less than half of that of sodium hydroxide (1588 kg).

[0056] Take 350 ml of tap water, add 125.3 g (calculated by Ca mass, which is 1.50 times the total mass of Mg in the tail water to be treated) of quicklime with a purity of 80 wt.% to prepare lime milk. The slurry is prepared by mechanical stirring at a stirring rate of 250 r / min and a stirring time of 10 min.

[0057] 5 L of tail water consisting of filtrate B and clear liquid A was taken into a beaker, placed in a water bath at 30°C, and the prepared lime milk was slowly poured into the slurry and stirred thoroughly for 40 minutes. After stirring, vacuum filtration was performed for 15 minutes to obtain calcium- and magnesium-containing solid slag and filtrate C. After drying, the calcium- and magnesium-containing solid slag had a water content of 28.66%. The dried calcium- and magnesium-containing solid slag was re-selected to separate by-products of calcium sulfate and magnesium hydroxide. The magnesium hydroxide was calcined to prepare active magnesium oxide, which was recycled as a precipitant.

[0058] The changes in indicators before and after tail water treatment are shown in Table 3.

[0059] Table 3. Chemical composition of tail water before and after treatment Unit: g / L

[0060]

[0061] As can be seen from Table 3, the main metal ions in the tail water are Mg 2+ Ionic solution, after adding slaked lime, generates precipitates containing magnesium and calcium. The Mg in filtrate C 2+ The ion concentration is less than 1g / L, and it can be recycled as acid leaching water or washing water, thereby achieving zero discharge of tail water.

[0062] Example 2

[0063] The chemical composition of the leachate after high-pressure leaching of laterite nickel ore with sulfuric acid solution and removal of iron and aluminum is shown in Table 4.

[0064] Table 4. Chemical composition of laterite nickel ore acid leaching solution Unit: g / L

[0065]

[0066] 5L of the leachate was placed in a beaker and placed in a constant-temperature water bath with stirring. 15.07g (0.7 times the total mass of Ni and Co) of activated magnesium oxide with a MgO content of 95wt.% and a citric acid activity of 33s was added and stirred thoroughly. The slurry was poured into a thickener, and the solid-liquid separation was observed and the settling time was recorded to obtain a clear liquid A and a solid-containing slurry. The solid-containing slurry was vacuum filtered, and the filter cake was washed with water and filtered again. The two filtrates, B, and clear liquid A, were mixed and treated as tail water to obtain the filter cake, which is MHP. A comparison of the effects of activated magnesium oxide and sodium hydroxide as precipitants under the same conditions is shown in Table 5.

[0067] Table 5. Comparison of the effects of activated magnesium oxide and sodium hydroxide as precipitants

[0068]

[0069] As shown in Table 5, the method of the present invention for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water has the following characteristics: the Ni content in MHP is comparable to that of conventional sodium hydroxide as a precipitant; the filter cake has a low moisture content; the sedimentation rate is much higher than that of sodium hydroxide; the method has good sedimentation rate and filtration rate; and the unit consumption of the precipitant is also much lower than that of sodium hydroxide.

[0070] Take 350 ml of tap water, add 137.7 g (calculated by Ca mass, which is 1.75 times the total mass of Mg in the tail water to be treated) of quicklime with a purity of 90 wt.% to prepare lime milk. The slurry is prepared by mechanical stirring at a stirring rate of 150 r / min and a stirring time of 20 min.

[0071] 5 L of tail water consisting of filtrate B and clear liquid A was taken into a beaker, placed in a water bath at 40°C, and the prepared lime milk was slowly poured into the slurry and stirred thoroughly for 60 minutes. After stirring, vacuum filtration was performed for 15 minutes to obtain calcium- and magnesium-containing solid slag and filtrate C. After drying, the calcium- and magnesium-containing solid slag had a water content of 27.95%. The dried calcium- and magnesium-containing solid slag was re-selected to separate by-products of calcium sulfate and magnesium hydroxide. The magnesium hydroxide was calcined to prepare active magnesium oxide, which was recycled as a precipitant.

[0072] The changes in indicators before and after tail water treatment are shown in Table 6.

[0073] Table 6. Chemical composition of tail water before and after treatment Unit: g / L

[0074]

[0075] As can be seen from Table 6, the main metal ions in the tail water are Mg 2+ Ionic solution, after adding slaked lime, generates precipitates containing magnesium and calcium. The Mg in filtrate C 2+ The ion concentration is less than 1g / L, and it can be recycled as acid leaching water or washing water, thereby achieving zero discharge of tail water.

[0076] Example 3

[0077] The modified calcium oxide powder prepared in the following manner was used to treat the tail water in this embodiment:

[0078] (a) N-aminoethyl-3-aminopropylmethyldimethoxysilane and 90 wt.% pure quicklime were added to ethanol and stirred for 2 h; the volume ratio of N-aminoethyl-3-aminopropylmethyldimethoxysilane to ethanol was 0.05:1, and the mass volume ratio of quicklime to N-aminoethyl-3-aminopropylmethyldimethoxysilane was 150:1 g / mL;

[0079] (b) adding carboxymethyl-β-cyclodextrin to water, stirring and mixing until uniform, and then adding to the mixture obtained in step (a), stirring and reacting for 1.5 hours; the mass volume ratio of carboxymethyl-β-cyclodextrin to water is 350:1g / L, and the amount of carboxymethyl-β-cyclodextrin is 1.2 times the amount of N-aminoethyl-3-aminopropylmethyldimethoxysilane;

[0080] (c) adding magnesium hydroxide seed particles to the mixture obtained in step (b), wherein the amount of the magnesium hydroxide seed particles added is 6% of the mass of the carboxymethyl-β-cyclodextrin, and heating to 70° C. with stirring and maintaining the stirring reaction for 5 hours. After the reaction is completed, filtering is performed, and the resulting filter residue is dried and crushed to obtain the modified calcium oxide.

[0081] Take 350 ml of tap water, add 137.7 g of modified quicklime to prepare lime milk, and the preparation is carried out by mechanical stirring at a stirring rate of 150 r / min and a stirring time of 20 min.

[0082] 5 L of tail water from Example 2 was taken, heated in a 40°C water bath, and the prepared lime milk was slowly added. The mixture was thoroughly stirred for 60 minutes. After stirring, vacuum filtration was performed for 9 minutes to obtain a calcium- and magnesium-containing solid slag and filtrate C. After drying, the calcium- and magnesium-containing solid slag had a water content of 28.23%. The dried calcium- and magnesium-containing solid slag was then re-selected to separate the byproducts calcium sulfate and magnesium hydroxide. The magnesium hydroxide was calcined to produce activated magnesium oxide, which was recycled as a precipitant. The changes in indicators before and after tail water treatment are shown in Table 7.

[0083] Table 7. Chemical composition of tail water before and after treatment Unit: g / L

[0084]

[0085] As can be seen from Table 7, the main metal ions in the tail water are Mg 2+ Ionic solution, after adding modified calcium oxide powder, generates precipitates containing magnesium and calcium. Mg in filtrate C 2+The ion concentration is less than 1g / L, and it can be recycled as acid leaching water or washing water, thereby achieving zero discharge of tail water.

[0086] Comparing Table 7 with Table 6, the modified lime or quicklime is used to treat the tail water. The composition of the filtrate after treatment is not much different, and both have good effects. The water content of the calcium and magnesium solid slag obtained by using modified lime to treat the tail water is not much different (28.23% and 27.95% respectively), but the vacuum filtration time is significantly reduced compared with lime as the tail water treatment reagent. It can be seen that the calcium and magnesium solid slag are easier to filter when the tail water is treated with modified lime.

[0087] 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 readily appreciate that other variations or modifications based on the above descriptions are possible. 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 claims of this patent application.

Claims

1. A method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water, characterized in that: The following steps are involved: (1) Laterite nickel ore is subjected to high-pressure acid leaching to obtain a solution to be refined; (2) adding active magnesium oxide to the solution to be extracted in step (1) to allow it to react fully; (3) The mixed solution after the reaction is concentrated to obtain a clear liquid and a solid slurry; (4) The solid slurry is filtered and washed with water to obtain MHP; (5) using a tail water treatment reagent to treat the tail water consisting of the clear liquid in step (3), the filtrate in step (4) and the water washing liquid, wherein the tail water treatment reagent is modified quicklime, which reacts with the tail water to obtain a solid slag containing calcium and magnesium, and the solid slag containing calcium and magnesium is separated by gravity separation to obtain calcium sulfate and magnesium hydroxide, and the magnesium hydroxide is calcined to prepare active magnesium oxide for use in step (2), thereby realizing the recycling of magnesium resources; the amount of the tail water treatment reagent added is calculated as the mass of Ca, which is 0.85 to 2.50 times the total mass of Mg in the tail water to be treated; The preparation method of the modified quicklime in step (5) is as follows: (a) Add aminosilane coupling agent and quicklime to ethanol and stir to react for 0.5 to 2 hours; (b) adding carboxymethyl-β-cyclodextrin to water, stirring and mixing until uniform, and then adding to the mixture obtained in step (a), stirring and reacting for 1 to 3 hours; (c) adding magnesium hydroxide seed particles to the mixture obtained in step (b), stirring and heating to 60-80° C. and maintaining stirring for 2-5 hours, filtering after the reaction is completed, and drying the filter residue to obtain modified calcium oxide; In step (a), the volume ratio of the aminosilane coupling agent to ethanol is 0.01 to 0.1:1, and the mass volume ratio of quicklime to the aminosilane coupling agent is (100 to 200): 1 g / mL; in step (b), the mass volume ratio of carboxymethyl-β-cyclodextrin to water is (300 to 400): 1 g / L, and the amount of carboxymethyl-β-cyclodextrin used is 1.1 to 1.5 times the amount of the aminosilane coupling agent; in step (c), the amount of magnesium hydroxide seed particles added is 5 to 10% of the mass of carboxymethyl-β-cyclodextrin.

2. The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water according to claim 1, characterized in that: In step (1), the acid used for high-pressure acid leaching of laterite nickel ore is a sulfuric acid solution.

3. The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water according to claim 1, characterized in that: In step (2): the magnesium oxide content in the active magnesium oxide is 88 to 99.8 wt.%; and the citric acid activity value of the active magnesium oxide is 10 to 100 s.

4. The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water according to claim 3, characterized in that: In step (2): the magnesium oxide content in the active magnesium oxide is 92.5 to 95.5 wt.%; and the citric acid activity value of the active magnesium oxide is 10 to 40 s.

5. The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water according to claim 1, characterized in that: In step (2): the amount of active magnesium oxide added is the amount of Ni in the solution to be extracted in step (1). 2+ and Co 2 + 0.5 to 1.0 times the total mass.

6. The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water according to claim 1, characterized in that: In step (2): the amount of active magnesium oxide added is the amount of Ni in the solution to be extracted in step (1). 2+ and Co 2 + 0.6 to 0.75 times the total mass.

7. The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water according to claim 1, characterized in that: In step (3): the mixed solution after the reaction is concentrated by natural sedimentation using a thickener, and the clear liquid and the solid slurry are obtained by layering.

8. The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water according to claim 1, characterized in that: In step (5): the tail water treatment reagent is added by dry powder addition or slurry addition; the tail water treatment reagent slurry concentration is greater than or equal to 30 wt.% and less than or equal to 70 wt.%; the slurry is mechanically stirred at a stirring rate of 100 to 500 r / min; the slurry mixing time is 3 to 300 min; the tail water treatment temperature is 10 to 60 ° C, and the reaction time between the tail water and the tail water treatment reagent is 10 to 180 min.

9. The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water according to claim 8, characterized in that: In step (5): the tail water treatment reagent is added by slurry mixing; the tail water treatment reagent slurry mixing concentration is 30wt.% to 55wt.%; the slurry mixing adopts mechanical stirring, and the stirring rate is 200 to 300r / min; the slurry mixing time is 5 to 10min; the amount of tail water treatment reagent added is 1.50 to 1.84 times the total mass of Mg in the tail water to be treated, calculated on the basis of Ca mass; the tail water treatment temperature is 20 to 40°C, and the reaction time between the tail water and the tail water treatment reagent is 30 to 60min.

10. The method for preparing MHP from laterite nickel ore using activated magnesium oxide and recycling tail water according to claim 1, characterized in that: In step (a), the volume ratio of the aminosilane coupling agent to ethanol is 0.05:1, and the mass volume ratio of quicklime to the aminosilane coupling agent is 150:1 g / mL; in step (b), the mass volume ratio of carboxymethyl-β-cyclodextrin to water is 350:1 g / L, and the amount of carboxymethyl-β-cyclodextrin is 1.2 times the amount of the aminosilane coupling agent; in step (c), the amount of magnesium hydroxide seed particles added is 6% of the mass of carboxymethyl-β-cyclodextrin.

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