Comprehensive utilization method of peridotite

Abstract

The invention provides a comprehensive utilization method of peridotite, which comprises the following steps: S100, adding the peridotite into a sulfuric acid solution with the concentration of 1.5-2.5 mol / L, and reacting for 25-90 minutes at the temperature of 85-105 DEG C according to the liquid-solid ratio of 5-8; then adjusting the temperature to 50-80 DEG C, reacting for 1-3 hours, and filtering to obtain a mixture of silica gel and talc and filtrate A; s200, washing the mixture of the silica gel and the talc, adding NaOH of which the mass is 0.35-0.65 times that of the SiO2 into the mixture, reacting for 10-30 minutes at the temperature of 60-90 DEG C, and filtering to obtain a water glass solution and a talc solid; s300, magnesium oxide is added into the filtrate A, the pH value of the filtrate is adjusted to 3-4, meanwhile, ferrous ions are fully oxidized, and goethite and filtrate B are obtained through filtering; s400, magnesium oxide is continuously added into the filtrate B, the pH value of the filtrate is adjusted to 7-8, filtering is conducted, and nickel hydroxide and filtrate C are obtained; s500, the filtrate C is subjected to evaporative crystallization, and magnesium sulfate crystals are obtained. According to the method, the overall utilization value of peridotite is remarkably improved, and new impurity elements are not introduced.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of minerals, and in particular relates to a comprehensive utilization method of peridotite. Background Art

[0002] Peridotite is a magnesium-rich silicate rock, mainly composed of olivine minerals (Li Dianhui. Mineralogical study of Pyang-Gaung olivine in Myanmar [D]. China University of Geosciences (Beijing), 2016.). As an important mineral resource, peridotite is widely used in refractory materials, building materials, fertilizers, casting and other fields. According to the statistical data of the Ministry of Natural Resources of my country in 2022, the national peridotite reserves are 160.08 million tons. In recent years, the amount of peridotite ore used in the preparation of refractory materials in my country has exceeded 17 million tons, the amount used in the preparation of building materials has exceeded 2.8 million tons, and the amount used in the preparation of fertilizers has exceeded 2.49 million tons (Ning Pengyuan, Wang Chunlian, Zhu Pingping, et al. Origin, distribution, deposit types and development and utilization status of peridotite in China [J / OL]. Chinese Geology, 1-22 [2024-10-14].).

[0003] In addition to the above uses, peridotite can also be used as an important raw material for extracting magnesium because its MgO content is as high as 30% to 50% (Ma Jianhua, Wang Baoren, Wang Xiuyan. Research on the process of preparing magnesium sulfate from pure peridotite [J]. Inorganic Salt Industry, 2009, 41 (11): 31-33.). In addition, peridotite also contains about 40% SiO2, 6% to 9% Fe and trace amounts of Ni, and these components have not been fully recycled in the previous magnesium extraction process. How to extract and utilize the elements in peridotite as comprehensively as possible without introducing new impurity elements (to avoid causing new waste) has become a technical problem that needs to be solved in this field.

[0004] If the magnesium, silicon, iron and nickel elements in peridotite can be separated, extracted and utilized at the same time, it will not only reduce solid waste emissions, but also greatly improve the utilization value and economic benefits of peridotite. Summary of the invention

[0005] Based on the above situation, the main purpose of the present invention is to provide a comprehensive utilization method of peridotite to solve the above problems existing in the prior art.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a method for comprehensive utilization of peridotite, comprising the following steps:

[0008] S100: crushing and grinding the peridotite to pass through a 200-mesh sieve, adding the mixture to a sulfuric acid solution having a concentration of 1.5 to 2.5 mol / L, wherein the liquid-to-solid ratio of the sulfuric acid solution to the peridotite is 5 to 8, and performing a first-stage reaction at a temperature of 85 to 105° C. for a reaction time of 25 to 90 min; then adjusting the temperature to 50 to 80° C. to continue the second-stage reaction for a reaction time of 1 to 3 hours, filtering, and obtaining a mixture of silica gel and talc and a filtrate A;

[0009] S200: After washing the mixture of silica gel and talc obtained in step S100, NaOH is added thereto, wherein the mass of NaOH is 0.35 to 0.65 times the mass of SiO2, reacting for 10 to 30 minutes at a temperature of 60 to 90° C., filtering, and obtaining a water glass solution with a modulus of 2 to 3.5 and a talc solid;

[0010] S300: adding magnesium oxide to the filtrate A obtained in step S100, adjusting the pH value of the filtrate to 3-4, and fully oxidizing the divalent iron ions by aeration or adding hydrogen peroxide, filtering to obtain goethite and filtrate B;

[0011] S400: Continue to add magnesium oxide to the filtrate B obtained in step S200, adjust the pH value of the filtrate to 7-8, and filter to obtain nickel hydroxide and filtrate C;

[0012] S500: Evaporating and crystallizing the filtrate C to obtain magnesium sulfate crystals.

[0013] Preferably, in step S100, the concentration of the sulfuric acid solution is preferably 2 mol / L, the liquid-to-solid ratio of the sulfuric acid solution to the peridotite is preferably 6, the reaction temperature of the first stage reaction is preferably 100°C, and the reaction time is preferably 60 min; and the reaction temperature of the second stage reaction is preferably 75°C, and the reaction time is preferably 2 hours.

[0014] Preferably, in step S200, the mixture of silica gel and talc is washed three times, the liquid-to-solid ratio of each washing is 3 to 6, and the duration of each washing is 20 to 30 minutes.

[0015] Preferably, the washing liquid is circulated and utilized progressively, and the first washing liquid obtained after the first washing in each round is used for preparing the sulfuric acid solution used in the next round of step S100; the second washing liquid obtained after the second washing is used as the first washing in the next round of step S200; and the third washing liquid obtained after the third washing is used as the second washing in the next round of step S200.

[0016] Preferably, in step S200, the mass of NaOH is preferably 0.4 times the mass of SiO2, the reaction temperature is preferably 80°C, and the reaction time is preferably 20 min.

[0017] Preferably, when oxidizing the divalent iron ions by aeration, the molar ratio of oxygen to divalent iron ions is 1-4.

[0018] Preferably, the molar ratio of oxygen to divalent iron ions used is preferably 2.5.

[0019] Preferably, when the divalent iron ions are oxidized by adding hydrogen peroxide, the molar ratio of the hydrogen peroxide to the divalent iron ions is 1 to 2, and the concentration of the hydrogen peroxide is 30%.

[0020] Preferably, the molar ratio of the hydrogen peroxide to the divalent iron ions used is preferably 1.5.

[0021] Preferably, in the step S500, when the filtrate C is evaporated and crystallized, the temperature range used is 90-110°C.

[0022] Preferably, in the step S500, when the filtrate C is evaporated and crystallized, the temperature used is preferably 100°C.

[0023] The invention provides a method for comprehensive utilization of peridotite, wherein silicon, iron, magnesium, nickel and other elements in the peridotite are extracted and prepared into water glass, goethite, magnesium sulfate and nickel hydroxide respectively, and high-purity talc solid is extracted at the same time, thereby greatly improving the overall utilization value of the peridotite. Moreover, the method does not introduce new impurity elements, has the advantages of high comprehensive utilization rate, high product added value, good economic benefit, and easy industrial application, and thus opens up a new way for comprehensive and efficient resource utilization of peridotite.

[0024] Other beneficial effects of the present invention will be explained in the specific implementation manner through the introduction of specific technical features and technical solutions. Through the introduction of these technical features and technical solutions, those skilled in the art should be able to understand the beneficial technical effects brought about by the technical features and technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[0026] Figure 1 A flow chart of a preferred implementation of the method for comprehensive utilization of peridotite provided by the present invention;

[0027] Figure 2 The present invention is a flowchart of another preferred embodiment of the method for comprehensive utilization of peridotite provided by the present invention. DETAILED DESCRIPTION

[0028] The present invention is described below based on embodiments, but the present invention is not limited to these embodiments. In the following detailed description of the present invention, some specific details are described in detail. In order to avoid confusing the essence of the present invention, known methods, processes, procedures, and components are not described in detail.

[0029] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0030] Unless the context clearly requires otherwise, throughout the specification and claims, the words "include", "comprising" and similar words should be interpreted in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to".

[0031] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0032] The present invention provides a method for comprehensive utilization of peridotite, comprising the following steps:

[0033] S100: crushing and grinding the peridotite to pass through a 200-mesh sieve, adding the mixture to a sulfuric acid solution having a concentration of 1.5 to 2.5 mol / L, wherein the liquid-to-solid ratio of the sulfuric acid solution to the peridotite is 5 to 8, and performing a first-stage reaction at a temperature of 85 to 105° C. for a reaction time of 25 to 90 min; then adjusting the temperature to 50 to 80° C. to continue the second-stage reaction for a reaction time of 1 to 3 hours, filtering, and obtaining a mixture of silica gel and talc and a filtrate A;

[0034] S200: After washing the mixture of silica gel and talc obtained in step S100, NaOH is added thereto, wherein the mass of NaOH is 0.35 to 0.65 times the mass of SiO2, reacting for 10 to 30 minutes at a temperature of 60 to 90° C., filtering, and obtaining a water glass solution with a modulus of 2 to 3.5 and a talc solid;

[0035] S300: adding magnesium oxide to the filtrate A obtained in step S100, adjusting the pH value of the filtrate to 3-4, and fully oxidizing the divalent iron ions by aeration or adding hydrogen peroxide, filtering to obtain goethite and filtrate B;

[0036] S400: Continue to add magnesium oxide to the filtrate B obtained in step S200, adjust the pH value of the filtrate to 7-8, and filter to obtain nickel hydroxide and filtrate C;

[0037] S500: Evaporating and crystallizing the filtrate C to obtain magnesium sulfate crystals.

[0038] Specifically, for step S100, the first stage reaction is an acid leaching reaction. By using the appropriate peridotite powder particle size, sulfuric acid solution concentration, liquid-solid ratio of sulfuric acid solution to peridotite, first stage reaction temperature and reaction time provided by the present invention, the talc (chemical formula: Mg3Si4O 10 (OH)2) basically does not participate in the reaction, while forsterite (chemical formula: (Mg,Fe)2[SiO4]) and magnesia nickel ore (chemical formula: (Ni,Mg)SiO3·nH2O) in peridotite can fully and smoothly react with sulfuric acid as follows:

[0039] (Mg,Fe)2[SiO4]+2H2SO4=2(Mg,Fe)SO4+H4SiO4

[0040] (Ni,Mg)SiO3·nH2O+H2SO4=(Ni,Mg)SO4+H4SiO4+(n-1)H2O

[0041] After the first stage reaction is completed, the reaction temperature is further adjusted, and the second stage reaction is continued in the solution obtained in the first stage. At this time, since the reaction temperature is suitable for the polymerization of orthosilicic acid, the orthosilicic acid will condense into silica gel. The reaction equation is as follows:

[0042] nH4SiO4=nSiO2·(n+1)H2O+(n-1)H2O.

[0043] At this time, filtration is performed, and the mixture of silica gel and talc is filtered out in a solid form, and the obtained liquid is filtrate A. In addition to the residual sulfuric acid, the main components of filtrate A include magnesium sulfate and ferrous sulfate, as well as a small amount of nickel sulfate.

[0044] Those skilled in the art can understand that crushing and grinding the peridotite to pass a 200-mesh sieve means that the particle size of the peridotite after crushing and grinding is less than 74 μm.

[0045] For step S200, the mixture of silica gel and talc obtained in step S100 must first be washed. The reason for washing is that due to the porosity of silica gel, a small amount of filtrate A will inevitably be adsorbed during the filtration process of step S100. In order to facilitate obtaining a purer water glass solution and talc solid through step S200, the mixture of silica gel and talc obtained through step S100 is washed to fully wash off the filtrate A adsorbed by the silica gel as much as possible, and then react with sodium hydroxide to obtain a water glass solution and talc solid. Both the water glass solution and the talc solid can be directly used in the industrial industry.

[0046] In this step, SiO2 in silica gel reacts with NaOH as follows:

[0047] 2NaOH+mSiO2=Na2O·mSiO2+H2O

[0048] Here, m is the modulus (ie, m is 2 to 3.5).

[0049] There is no strict restriction on the implementation order of step S200, that is, although the step is named "S200", it can be implemented after step S100. It does not have to be performed before step S300. It can also be performed after step S300, or even S400, or S500, or it can be performed simultaneously with one or more steps among steps S300, S400, S500, etc.

[0050] For step S300, the acidity of the filtrate A is appropriately adjusted from the original significantly acidic environment to a pH value within the range of 3 to 4, so that the oxidation of divalent iron ions can proceed smoothly. The adjusting substance added when adjusting the pH value is magnesium oxide, and the oxidant added during the oxidation process is oxygen or hydrogen peroxide. It can be seen that in the process of extracting iron in step S300, the metal element contained in the introduced auxiliary substance is magnesium, and magnesium already exists in the filtrate A. Therefore, step S300 does not introduce new other metal elements (impurity elements), and will not cause waste of other metal elements, which significantly improves the economic benefits of the comprehensive utilization of peridotite.

[0051] In step S300, in order to control the amount of magnesium oxide added to be appropriate, it can be achieved by monitoring the pH value of the filtrate while adding it in small amounts. Specifically, magnesium oxide is first added until the pH value of the filtrate becomes 3-4, and the pH value of the filtrate is continuously monitored in real time. Once the pH value of the filtrate drops below 3, magnesium oxide is continuously added thereto to return the pH value to between 3 and 4. When magnesium oxide does not need to be added for more than 20 minutes and the pH value does not drop below 3, it can be determined that the divalent iron ions have been fully oxidized (of course, the amount of hydrogen ions and iron ions to be reacted in the filtrate A can also be calculated in advance, and the amount of magnesium oxide to be consumed can be calculated by the corresponding reaction equation, and the magnesium oxide can be added at one time);

[0052] When the divalent iron ions are oxidized by aeration, the chemical reactions occurring in step S300 include:

[0053] MgO+2H + =Mg 2+ +H2O

[0054] 4Fe 2++2H2O+O2+4MgO=4FeOOH↓+4Mg 2+

[0055] When the divalent iron ions are oxidized by adding hydrogen peroxide, the chemical reactions occurring in step S300 include:

[0056] MgO+2H + =Mg 2+ +H2O

[0057] 2Fe 2+ +H2O2+2H + =2Fe 3+ +2H2OFe 3+ +2H2O=FeOOH↓+3H +

[0058] After the oxidation reaction of the divalent iron ions in step S300 is fully completed, filtration is performed, and the solid obtained at this time is goethite (chemical formula: FeOOH), and the remaining liquid is filtrate B, which mainly contains magnesium sulfate and a small amount of nickel sulfate.

[0059] For step S400, the pH value of the filtrate B is appropriately adjusted by continuing to add an appropriate amount of magnesium oxide to a pH value of 7 to 8, so that the nickel element can be smoothly extracted and deposited in the form of nickel hydroxide. The chemical reactions occurring in this step include:

[0060] MgO+2H + =Mg 2+ +H2O

[0061] Ni 2+ +H2O+MgO=Ni(OH)2↓+Mg 2+

[0062] In this step, in order to control the amount of magnesium oxide added to be appropriate, it can be achieved by adding it in small amounts while monitoring the pH value of the filtrate. Specifically, magnesium oxide is first added until the pH value of the filtrate becomes 7-8, and the pH value of the filtrate is continuously monitored in real time. Once the pH value of the filtrate drops below 7, magnesium oxide is continuously added thereto to return the pH value to between 7 and 8. When magnesium oxide does not need to be added for more than 20 minutes and the pH value does not drop below 7, it can be determined that the nickel element has been extracted and deposited (of course, the amount of hydrogen ions and nickel ions to be reacted in the filtrate B can also be calculated in advance, the amount of magnesium oxide to be consumed can be calculated by the corresponding reaction equation, and the magnesium oxide can be added all at once).

[0063] After the Ni element is fully deposited, the nickel hydroxide solid and the filtrate C are obtained by filtration. The main component of the filtrate C is magnesium sulfate. At this time, the filtrate C is evaporated and crystallized in step S500 to obtain magnesium sulfate crystals.

[0064] The present invention provides a method for comprehensive utilization of peridotite, which extracts silicon, iron, magnesium, nickel and other elements in peridotite into water glass, goethite, magnesium sulfate and nickel hydroxide respectively, and simultaneously extracts high-purity talc solid, thereby greatly improving the overall utilization value of peridotite. Moreover, the method does not introduce new impurity elements, has the advantages of high comprehensive utilization rate, high product added value, good economic benefits, easy industrialization and the like, and opens up a new way for comprehensive and efficient resource utilization of peridotite.

[0065] Preferably, in step S100, the concentration of the sulfuric acid solution is preferably 2 mol / L, the liquid-to-solid ratio of the sulfuric acid solution to the peridotite is preferably 6, the reaction temperature of the first stage reaction is preferably 100°C, and the reaction time is preferably 60 min; and the reaction temperature of the second stage reaction is preferably 75°C, and the reaction time is preferably 2 h.

[0066] By the above preferred selection of the reaction parameters in step S100, the reaction rate of step S100 can be further improved, thereby optimizing the implementation efficiency of the comprehensive utilization method of peridotite of the present invention.

[0067] Preferably, in step S200, the mixture of silica gel and talc is washed three times, the liquid-to-solid ratio of each washing is 3 to 6, and the duration of each washing is 20 to 30 minutes.

[0068] Preferably, the washing liquid is circulated and utilized progressively, and the first washing liquid obtained after the first washing in each round is used for preparing the sulfuric acid solution used in the next round of step S100; the second washing liquid obtained after the second washing is used as the first washing in the next round of step S200; and the third washing liquid obtained after the third washing is used as the second washing in the next round of step S200.

[0069] Specifically, because in industrial production, the above steps S100-S500 are usually performed in multiple rounds, after the step S100 in the first round is completed, the step S100 in the second round can be started with the next batch of peridotite raw materials, so the washing liquid used for washing the mixture of silica gel and talc can be cyclically utilized, and the first washing liquid obtained after the first washing in each round is used for the preparation of the sulfuric acid solution used in the next round of step S100; the second washing liquid obtained after the second washing is used as the first washing in the next round of step S200; the third washing liquid obtained after the third washing is used as the second washing in the next round of step S200, and the third washing in the next round of step S200 can be achieved with clean water (clean water is also used for the first washing in the first round), and the cyclical utilization is continued until the last round of washing of the mixture of silica gel and talc is completed.

[0070] Preferably, in step S200, the mass of NaOH is preferably 0.4 times the mass of SiO2, the reaction temperature is preferably 80°C, and the reaction time is preferably 20 min.

[0071] The above parameter settings are helpful to increase the reaction rate of silicon dioxide and sodium hydroxide, that is, to increase the generation rate of water glass solution.

[0072] Preferably, when oxidizing the divalent iron ions by aeration, the molar ratio of oxygen to divalent iron ions is 1-4.

[0073] Preferably, the molar ratio of oxygen to divalent iron ions used is preferably 2.5.

[0074] Preferably, when the divalent iron ions are oxidized by adding hydrogen peroxide, the molar ratio of the hydrogen peroxide to the divalent iron ions is 1 to 2, and the concentration of the hydrogen peroxide is 30%.

[0075] Preferably, the molar ratio of the hydrogen peroxide to the divalent iron ions used is preferably 1.5.

[0076] By selecting the above parameters, it is possible to ensure that the divalent iron ions are fully oxidized while increasing their oxidation rate as much as possible, which is beneficial to the efficient precipitation of goethite.

[0077] Preferably, in the step S500, when the filtrate C is evaporated and crystallized, the temperature range used is 90-110°C.

[0078] Preferably, in the step S500, when the filtrate C is evaporated and crystallized, the temperature used is preferably 100°C.

[0079] Through the above arrangement, magnesium sulfate crystals can be obtained efficiently, quickly and fully without causing excessive waste of heating resources.

[0080] The present invention mainly utilizes the following equipment when carrying out the above-mentioned method for comprehensive utilization of peridotite:

[0081] ① A jaw crusher and a Raymond mill for crushing and grinding the peridotite in step S100;

[0082] ② A reaction kettle or reaction tank used for various reactions in steps S100, S200, S300, and S400;

[0083] ③ A filter press for solid-liquid separation in steps S100, S200, S300, and S400;

[0084] ④ An evaporator and a crystallizer for evaporating and crystallizing the filtrate C in step S500;

[0085] ⑤ Bag-type fine filter and centrifuge for crystallization separation in step S500;

[0086] ⑥ Tanks or tanks used to prepare sulfuric acid solutions and store various solutions (slurries), as well as corresponding supporting conveying devices.

[0087] Embodiment 1:

[0088] The content of MgO in the peridotite of this embodiment is 39.04%, the content of SiO2 is 33.35%, the content of FeO is 7.75%, the content of Fe2O3 is 0.51%, and the content of Ni is 0.25%. The specific steps are as follows:

[0089] Step S100: After the peridotite is crushed and ground to a particle size of less than 74 μm, it is added to a sulfuric acid solution with a concentration of 1.5 mol / L according to a liquid-to-solid ratio of 8, and a first-stage reaction is carried out at a temperature of 100° C. for 30 min; then a second-stage reaction is continued at a temperature of 80° C. for 1.5 hours, and filtered to obtain a mixture of silica gel and talc and a filtrate A;

[0090] Step S200: After washing the mixture of silica gel and talc, NaOH is added thereto, the mass of NaOH being 0.4 times the mass of SiO2, reacting for 10 minutes at 90°C, filtering, and obtaining a water glass solution with a modulus of 2.5 and a talc solid;

[0091] Step S300: magnesium oxide is added to the filtrate A under stirring conditions to adjust the pH value of the filtrate to 3.2-3.7, and the divalent iron ions are fully oxidized by aeration, and goethite and filtrate B are obtained by filtration:

[0092] Step S400: adding magnesium oxide to the filtrate B under stirring conditions, adjusting the pH of the solution to 7.5-8 at the end point, causing the nickel ions to undergo a hydrolysis reaction, and filtering to obtain nickel hydroxide and filtrate C:

[0093] Step S500: evaporating and crystallizing the filtrate C to obtain magnesium sulfate crystals.

[0094] Embodiment 2:

[0095] The content of MgO in the peridotite of this embodiment is 48.01%, the content of SiO2 is 42.42%, the content of FeO is 6.77%, the content of Fe2O3 is 1.51%, and the content of Ni is 0.28%. The specific steps are as follows:

[0096] Step S100: After the peridotite is ground to a particle size of more than 90% less than 74 μm, the mixture is added to a sulfuric acid solution with a concentration of 2.5 mol / L according to a liquid-to-solid ratio of 5, and a first-stage reaction is carried out at a temperature of 90° C. for 40 min; a second-stage reaction is then carried out at a temperature of 70° C. for 1 hour, and the mixture is filtered to obtain a mixture of silica gel and talc and a filtrate A;

[0097] Step S200: After washing the mixture of silica gel and talc, NaOH is added thereto, the mass of NaOH being 0.46 times the mass of SiO2, reacting for 20 minutes at 90°C, filtering, and obtaining a water glass solution with a modulus of 3 and talc solid;

[0098] Step S300: adding magnesium oxide to the filtrate A under stirring conditions to adjust the pH value of the filtrate to 3-3.5, and fully oxidizing the divalent iron ions by aeration or adding hydrogen peroxide, and filtering to obtain goethite and filtrate B;

[0099] Step S300: adding magnesium oxide to the filtrate B under stirring conditions, adjusting the pH of the solution to 7.3-7.8 at the end point to hydrolyze the nickel ions, and filtering to obtain nickel hydroxide and the filtrate C;

[0100] Step S500: evaporating and crystallizing the filtrate C to obtain magnesium sulfate crystals.

[0101] Those skilled in the art will appreciate that, without conflict, the above-mentioned preferred solutions can be freely combined and superimposed.

[0102] It should be understood that the above-mentioned embodiments are merely illustrative and not restrictive. Without departing from the basic principles of the present invention, various obvious or equivalent modifications or substitutions that can be made by those skilled in the art to the above-mentioned details will all be included in the scope of the claims of the present invention.

Claims

1. A method for comprehensive utilization of peridotite, characterized in that: The following steps are involved: S100: crushing and grinding the peridotite to pass through a 200-mesh sieve, adding the mixture to a sulfuric acid solution having a concentration of 1.5 to 2.5 mol / L, wherein the liquid-to-solid ratio of the sulfuric acid solution to the peridotite is 5 to 8, and performing a first-stage reaction at a temperature of 85 to 105° C. for a reaction time of 25 to 90 min; then adjusting the temperature to 50 to 80° C. to continue the second-stage reaction for a reaction time of 1 to 3 hours, filtering, and obtaining a mixture of silica gel and talc and a filtrate A; S200: After washing the mixture of silica gel and talc obtained in step S100, NaOH is added thereto, wherein the mass of NaOH is 0.35 to 0.65 times the mass of SiO2, reacting for 10 to 30 minutes at a temperature of 60 to 90° C., filtering, and obtaining a water glass solution with a modulus of 2 to 3.5 and a talc solid; S300: adding magnesium oxide to the filtrate A obtained in step S100, adjusting the pH value of the filtrate to 3-4, and fully oxidizing the divalent iron ions by aeration or adding hydrogen peroxide, filtering to obtain goethite and filtrate B; S400: Continue to add magnesium oxide to the filtrate B obtained in step S200, adjust the pH value of the filtrate to 7-8, and filter to obtain nickel hydroxide and filtrate C; S500: Evaporating and crystallizing the filtrate C to obtain magnesium sulfate crystals.

2. The method according to claim 1, characterized in that In step S100, the concentration of the sulfuric acid solution is preferably 2 mol / L, the liquid-to-solid ratio of the sulfuric acid solution to the peridotite is preferably 6, the reaction temperature of the first stage reaction is preferably 100°C, and the reaction time is preferably 60 min; and the reaction temperature of the second stage reaction is preferably 75°C, and the reaction time is preferably 2 hours.

3. The method according to claim 1, characterized in that In the step S200, the mixture of silica gel and talc is washed three times, the liquid-to-solid ratio of each washing is 3-6, and the duration of each washing is 20-30 minutes.

4. The method according to claim 3, characterized in that The washing liquid is circulated and utilized progressively. The first washing liquid obtained after the first washing in each round is used for preparing the sulfuric acid solution used in the next round of step S100; the second washing liquid obtained after the second washing is used as the first washing in the next round of step S200; and the third washing liquid obtained after the third washing is used as the second washing in the next round of step S200.

5. The method according to claim 1, characterized in that In the step S200, the mass of NaOH is preferably 0.4 times the mass of SiO2, the reaction temperature is preferably 80°C, and the reaction time is preferably 20 minutes.

6. The method according to claim 1, characterized in that When oxidizing the divalent iron ions by aeration, the molar ratio of oxygen to divalent iron ions used is 1 to 4.

7. The method according to claim 6, characterized in that The molar ratio of oxygen to ferrous ions used is preferably 2.

5.

8. The method according to claim 1, characterized in that When the divalent iron ions are oxidized by adding hydrogen peroxide, the molar ratio of the hydrogen peroxide to the divalent iron ions is 1 to 2, and the concentration of the hydrogen peroxide is 30%.

9. The method according to claim 8, characterized in that The molar ratio of hydrogen peroxide to divalent iron ions used is preferably 1.

5.

10. The method according to claim 1, characterized in that In step S500, when the filtrate C is evaporated and crystallized, the temperature range used is 90-110°C.

11. The method according to claim 10, characterized in that In the step S500, when the filtrate C is evaporated and crystallized, the temperature used is preferably 100°C.

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