Method for treating magnesium-containing minerals

Abstract

The invention provides a treatment method of magnesium-containing minerals. The treatment method comprises the following steps: mixing the magnesium-containing mineral with first hydrochloric acid, carrying out first leaching treatment, and carrying out solid-liquid separation on a product to obtain first leaching filtrate and first leaching filter residues; carrying out iron and aluminum precipitation treatment on the first leaching filtrate and a first neutralizer, and carrying out solid-liquid separation on a product to obtain iron and aluminum removed liquid and iron and aluminum slag; carrying out nickel and cobalt precipitation treatment on the iron and aluminum removed liquid and a second neutralizer, and carrying out solid-liquid separation on a product to obtain nickel and cobalt slag and magnesium chloride containing liquid; the first leaching filter residues and second hydrochloric acid are mixed for second leaching treatment, and second leaching filtrate and second leaching filter residues are obtained after a product is subjected to solid-liquid separation; returning the second leaching filtrate to a mixture of magnesium-containing minerals and first hydrochloric acid for first leaching treatment; and obtaining silicon slag from the second leaching filter residue. The method can solve the problem of low valuable metal recovery rate in the magnesium-containing mineral acid leaching process in the prior art, and is suitable for the field of metallurgy.

Description

Technical Field

[0001] The invention relates to the field of metallurgy, and in particular to a method for treating magnesium-containing minerals. Background Art

[0002] China is one of the major countries with magnesium-containing mineral resources, with proven reserves of 5 billion tons. Magnesium-containing minerals include serpentine, magnesite, dolomite and other minerals. Taking serpentine as an example, serpentine can be used in fertilizer manufacturing, refractory material production, roadbed and pavement filling, ceramic production, building materials processing, jade processing, metallurgical additives, chemical product processing and mineral product recovery. Among them, the processing of chemical products (metal magnesium, magnesium oxide, magnesium hydroxide, silicon products, iron red) and the recovery of mineral products (nickel, platinum, chromium, etc.) are the main research directions of serpentine comprehensive utilization research.

[0003] The main component of serpentine is magnesium silicate, which has a high magnesium content. In the research and practice of serpentine leaching in my country, the leaching agents used are divided into two methods: acid leaching and alkaline leaching. The alkaline leaching method is less used. The acid leaching method mostly uses sulfuric acid, and a small amount of leaching agent is hydrochloric acid. The existing mature serpentine leaching process is a sulfuric acid system, and there is no mature hydrochloric acid leaching process. However, the leaching effect of the sulfuric acid leaching process is not ideal. There are problems such as slow leaching rate, low magnesium ion leaching rate and low leaching residue recovery rate. These problems lead to large consumption of serpentine raw materials, poor comprehensive recovery effect, and poor economic benefits.

[0004] Although patent CN103215446 discloses a clean production method for hydrochloric acid atmospheric pressure leaching of serpentine laterite nickel ore, which mainly includes: mixing serpentine laterite nickel ore with hydrochloric acid for atmospheric pressure leaching reaction, so that nickel, cobalt, iron and magnesium are leached into the acid leaching solution, and silicon enters the slag phase; then the acid leaching solution is quantitatively injected into a calcination and hydrolysis furnace for calcination reaction, and the hydrogen chloride gas generated at the top of the furnace is separated from magnesium oxide by a multi-stage dust removal system and then enters an absorption tower to achieve hydrochloric acid regeneration. The mixed oxide powder collected at the bottom of the calcination furnace is mainly composed of iron oxide, which contains nickel oxide and a small amount of cobalt oxide, magnesium oxide and aluminum oxide. The mixed oxide powder is used as a raw material for subsequent blast furnace reduction smelting to produce nickel iron. However, the hydrochloric acid atmospheric pressure leaching production method has the following problems: (1) During the hydrochloric acid atmospheric pressure leaching process, only one stage of leaching is used, and the impurities and magnesium are not completely leached. The unleached oxides (such as magnesium and iron) enter the silicon slag, resulting in a complex silicon slag composition, low utilization value, and high production cost for subsequent silicon product preparation; (2) The separation of nickel iron and magnesium by hydrolysis and calcination fails to achieve the separation of valuable metals Ni / Co and iron elements, and the recovery loss of Mg elements is high. (3) The acid leaching solution is directly calcined and hydrolyzed without concentration, and the water content in the flue gas is high, resulting in high energy consumption. (4) The calcination and hydrolysis of the acid leaching solution is highly corrosive to equipment and has high cost.

[0005] In summary, the leaching effect of the existing magnesium-containing mineral acid leaching process is not ideal, and there is still no systematic optimization research on the hydrochloric acid acid leaching process. There are problems such as complex composition of leached silicon slag, low utilization value, high loss of Mg element recovery, low recovery rate of valuable metal Ni / Co, and high energy consumption. Therefore, it is necessary for the present invention to provide a new treatment method for magnesium-containing minerals to solve the above problems and further improve the comprehensive utilization rate of magnesium-containing minerals. Summary of the invention

[0006] The main purpose of the present invention is to provide a method for treating magnesium-containing minerals to solve the problems of unsatisfactory leaching effect and low recovery rate of valuable metals Ni and Co in the acid leaching process of magnesium-containing minerals in the prior art.

[0007] In order to achieve the above-mentioned purpose, according to a first aspect of the present invention, there is provided a method for treating magnesium-containing minerals, comprising the following steps: mixing the magnesium-containing mineral with a first hydrochloric acid for a first leaching treatment, and obtaining a first leaching filtrate and a first leaching residue after solid-liquid separation of the product; treating the first leaching filtrate with a first neutralizer for iron-aluminum precipitation, and obtaining a liquid after iron-aluminum removal and an iron-aluminum slag after solid-liquid separation of the product; treating the liquid after iron-aluminum removal with a second neutralizer for nickel-cobalt precipitation, and obtaining a nickel-cobalt slag and a liquid after magnesium chloride after solid-liquid separation of the product; mixing the first leaching residue with a second hydrochloric acid for a second leaching treatment, and obtaining a second leaching filtrate and a second leaching residue after solid-liquid separation of the product; returning the second leaching filtrate to the mixture of the magnesium-containing mineral and the first hydrochloric acid for the first leaching treatment; and sequentially slurrying, washing, filtering and drying the second leaching residue to obtain silicon slag.

[0008] Furthermore, the temperature of the first leaching treatment is 50-105° C., and the time is 0.5-20 h; preferably, the hydrochloric acid concentration of the system after the first leaching treatment is 5-30 g / L.

[0009] Furthermore, the temperature of the second leaching treatment is 50-105° C., and the time is 0.5-20 h; preferably, the hydrochloric acid concentration of the system after the second leaching treatment is 40-120 g / L.

[0010] Further, the first neutralizer and the second neutralizer are each independently selected from one or more of MgO, MgCO3, NaOH, Mg, Ca(OH)2 or CaO.

[0011] Furthermore, the pH value of the iron-aluminum precipitation treatment is 3-5; preferably, the temperature of the iron-aluminum precipitation treatment is 50-100° C., and the time is 0.5-20 hours.

[0012] Furthermore, after removing iron and aluminum, Mg 2+ Concentration ≤52g / L.

[0013] Furthermore, the endpoint pH value of the system after the nickel-cobalt precipitation treatment is greater than 7.0; preferably, the temperature of the nickel-cobalt precipitation treatment is 30-100° C., and the time is 0.5-20 h.

[0014] Furthermore, before the magnesium-containing mineral is mixed with the first hydrochloric acid, the magnesium-containing mineral is subjected to grinding and magnetic separation in sequence; preferably, the particle size of the magnesium-containing mineral after grinding is 80 to 250 mesh; preferably, the intensity of the magnetic separation is 150 to 250 ka / m.

[0015] Furthermore, the heating method of the second leaching treatment is steam heating, and the pressure of the saturated steam of the steam is 0.1-0.4 MPa.

[0016] Furthermore, the magnesium chloride-containing liquid is added with a decalcifying agent to remove calcium, and then evaporated and crystallized to obtain magnesium chloride hexahydrate; the magnesium chloride hexahydrate is then thermally decomposed to obtain magnesium oxide and hydrochloric acid; preferably, the decalcifying agent is selected from CO2.

[0017] Furthermore, the magnesium-containing mineral includes serpentine, magnesite or dolomite; preferably, after the magnesium-containing mineral is mixed with the first hydrochloric acid for the first leaching treatment, the first leaching filtrate contains magnesium ions, chloride ions, iron ions and nickel ions.

[0018] By applying the technical solution of the present invention and treating magnesium-containing minerals through the above-mentioned treatment method, it is possible to solve the problems of unsatisfactory leaching effect of the acid leaching process of magnesium-containing minerals in the prior art, complex composition of leached silicon slag and low utilization value, high loss of Mg element recovery, low recovery rate of valuable metals Ni / Co and high energy consumption, and to achieve efficient treatment of magnesium-containing minerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 A schematic flow chart of a method for treating magnesium-containing minerals according to an embodiment of the present invention is shown;

[0021] Figure 2 The relationship between the pH of the iron and aluminum precipitation treatment and the ion concentrations of Ni, Co, Fe, and Al in the solution after the iron and aluminum precipitation is shown;

[0022] Figure 3 It shows that the Mg content in the liquid after iron and aluminum removal 2+ The relationship between the concentration and the ion concentration in the solution after nickel and cobalt precipitation;

[0023] Figure 4 The phase diagram of the nickel-cobalt slag in Example 1 is shown. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0025] As described in the background technology section of this application, the leaching effect of the prior art acid leaching process of magnesium-containing minerals is not ideal, and there are problems such as complex components of the leached silicon slag, low utilization value, high loss of Mg element recovery, low recovery rate of valuable metal Ni / Co, and high energy consumption. In order to solve this problem, this application provides a treatment method for magnesium-containing minerals, such as Figure 1 As shown, the method comprises the following steps: mixing the magnesium-containing mineral with the first hydrochloric acid for the first leaching treatment, and obtaining the first leaching filtrate and the first leaching residue after solid-liquid separation of the product; treating the first leaching filtrate with the first neutralizer for iron-aluminum precipitation, and obtaining the iron-aluminum-removed liquid and iron-aluminum slag after solid-liquid separation of the product; treating the iron-aluminum-removed liquid with the second neutralizer for nickel-cobalt precipitation, and obtaining the nickel-cobalt slag and the magnesium chloride-containing liquid after solid-liquid separation of the product; mixing the first leaching residue with the second hydrochloric acid for the second leaching treatment, and obtaining the second leaching filtrate and the second leaching residue after solid-liquid separation of the product; returning the second leaching filtrate to the mixture of the magnesium-containing mineral and the first hydrochloric acid for the first leaching treatment; and sequentially slurrying, washing, filtering and drying the second leaching residue to obtain silicon slag.

[0026] The present invention provides a process for "two-stage countercurrent leaching treatment" of magnesium-containing minerals in a hydrochloric acid system, wherein the first leaching treatment can leach iron, aluminum, nickel, cobalt and most of magnesium, and the second leaching treatment can leach the remaining difficult-to-leach Mg-containing minerals in the first leaching residue. At the same time, in order to make full use of the residual acid and improve the leaching rate of the metal elements, the second leaching filtrate is then returned to the first leaching treatment. After the above-mentioned "two-stage countercurrent leaching treatment" steps, the effective separation of silicon from iron, aluminum, nickel, cobalt and magnesium in the magnesium-containing minerals is achieved, and the silicon slag (mainly composed of SiO2) finally obtained has a high silicon content and less impurities, which can be used as a raw material for silicon products such as industrial silicon. At the same time, the above-mentioned steps also reduce the consumption of hydrochloric acid in the acid leaching treatment and the consumption of neutralizers in the subsequent precipitation of iron, aluminum, nickel and cobalt.

[0027] Furthermore, the present invention sequentially performs iron-aluminum precipitation treatment and nickel-cobalt precipitation treatment on the first leaching filtrate after the first leaching treatment, and obtains iron-aluminum slag, nickel-cobalt slag and magnesium chloride-containing liquid. Through the above operation, the effective recycling of magnesium element and the recovery of valuable metals nickel and cobalt are achieved, and the Ni and Co grades in the recovered nickel-cobalt slag are relatively high.

[0028] In summary, the various steps in the treatment method of magnesium-containing minerals of the present invention cooperate with each other, and finally silicon slag with high utilization value and low impurity content, magnesium chloride-containing liquid with high magnesium recovery rate, and valuable metal Ni / Co with high recovery rate can be obtained. Among them, the leaching rates of Mg, Fe, Ni, Co, and Mg can all reach more than 96%, greatly improving the comprehensive utilization efficiency of magnesium-containing minerals. At the same time, the consumption of hydrochloric acid and neutralizer in the treatment method of the present invention is low, the production energy consumption is low, and the economic benefit is high.

[0029] The magnesium-containing minerals include but are not limited to serpentine, and may also be magnesium-containing minerals such as magnesite and dolomite. After these magnesium-containing minerals are leached with hydrochloric acid, the leachate contains magnesium ions, chloride ions, iron ions and nickel ions.

[0030] It is further explained here that the main components of serpentine include 10-30wt% Si, 15-30wt% Mg, 2-8wt% Fe, 0.1-5wt% Al, 0.01-1wt% Co, 0.01-1wt% Ni, 0.1-2wt% Mn and 0.05-2wt% Ca, as well as other elements such as O and H.

[0031] In order to further improve the leaching rate and efficiency of metal elements, the temperature of the first leaching treatment is preferably 50-105°C and the time is 0.5-20 hours. The temperature of the second leaching treatment is preferably 50-105°C and the time is 0.5-20 hours.

[0032] In order to further balance the leaching rate of metal elements and the amount of neutralizer used in subsequent iron and aluminum precipitation treatments and nickel and cobalt precipitation treatments, the hydrochloric acid (HCl) concentration of the system after the first leaching treatment is preferably 5 to 30 g / L.

[0033] In order to further improve the separation effect of Mg and Si, the hydrochloric acid (HCl) concentration of the system after the second leaching treatment is preferably 40-120 g / L. The present invention increases the hydrochloric acid concentration of the system after the second leaching treatment, leaches the Mg-containing minerals that are difficult to leach in the first leaching residue, thereby improving the recovery rate of the Mg element and reducing the impurities in the silicon slag product.

[0034] In a preferred embodiment, the first leaching treatment and the second leaching treatment are carried out under normal pressure. The normal pressure leaching treatment has low pressure resistance requirements for the equipment, and hydrochloric acid is less corrosive to the equipment under normal pressure. Preferably, the concentrations of the first hydrochloric acid and the second hydrochloric acid are independently 25 to 37 wt%.

[0035] In order to further improve the leaching rate of metal elements, iron-aluminum slag, nickel-cobalt slag and magnesium chloride-containing liquid with high separation degree are obtained. Preferably, the first neutralizer and the second neutralizer are independently selected from one or more of MgO, MgCO3, NaOH, Mg, Ca(OH)2 or CaO. NaOH can be added to the reaction system in the form of a solution, and the ore pulp containing CaO can also be used as a neutralizer to reduce costs.

[0036] In a preferred embodiment, the pH value of the iron and aluminum precipitation treatment is 4.2 to 4.8. The present invention controls the pH value of the iron and aluminum precipitation treatment within the range of 4.2 to 4.8. This is based on the inventor's study of the effect of the pH of the iron and aluminum precipitation treatment on the concentration of metal ions in the solution after the iron and aluminum precipitation. Figure 2 As shown, when the pH value is within the range of 4.2 to 4.8, the concentration of Fe and Al ions in the liquid can be reduced to below 1 mg / L after iron and aluminum removal, and at this time, high-value metals such as nickel and cobalt will still not precipitate in large quantities into the iron and aluminum slag to cause losses.

[0037] In order to achieve effective separation of magnesium and nickel-cobalt and improve the grade of nickel-cobalt slag, the endpoint pH value of the system after nickel-cobalt precipitation treatment is greater than 7.0, and more preferably the pH value is ≥ 7.2. Preferably, the temperature of nickel-cobalt-manganese precipitation treatment is 30-100°C and the time is 0.5-20h. More preferably, the temperature of nickel-cobalt-manganese precipitation treatment is 50-90°C.

[0038] In a preferred embodiment, the Mg in the liquid after iron and aluminum removal is 2+ Concentration ≤52g / L. Before the nickel-cobalt precipitation treatment, the present invention needs to control the Mg content in the liquid after iron and aluminum removal. 2+ The concentration is below 52g / L (including 52g / L), which is based on the inventor's research on Mg in the liquid after iron and aluminum removal. 2+ The concentration of Mg has an unexpected effect on the ion concentration of Ni and Co in the solution after nickel and cobalt precipitation. 2+ When the concentration exceeds 52g / L, after the neutralizer is added, the pH value increases to a certain value, but the pH value will not rise rapidly with the addition of the neutralizer, and the pH value of nickel-cobalt precipitation end point of 7.2 or above cannot be reached. Therefore, the nickel-cobalt precipitation effect is not good. In addition, the magnesium ion concentration in the solution after nickel-cobalt precipitation will decrease significantly due to the entry of Mg in the nickel-cobalt slag. The product is as follows: Figure 3 As shown, the above results in a low recovery rate of Ni and Co in the nickel-cobalt slag, a low grade, and a relatively high magnesium content, which reduces the economic value and grade of the nickel-cobalt slag.

[0039] And when Mg 2+When the concentration exceeds 52g / L, when you want to reach the end pH value of nickel-cobalt precipitation treatment, the pH value will not rise rapidly with the addition of neutralizer, and the Mg ion concentration in the solution will drop significantly after nickel-cobalt precipitation. At the same time, a large amount of slag is produced, and the Mg content in the nickel-cobalt slag is high, while the Ni and Co contents are low. For example, when Mg 2+ When the concentration is 49 g / L, the endpoint pH value of the nickel-cobalt precipitation treatment is 7.2, wherein the components of the nickel-cobalt precipitation slag include: 40.28% Mg, 0.067% Ni and 0.012% Co; for example, when Mg 2+ When the concentration is 45g / L, the endpoint pH value of nickel-cobalt precipitation treatment is 7.4, wherein the components of nickel-cobalt precipitation slag include: 41.26% Mg, 0.145% Ni and 0.027% Co; for example, when Mg 2+ When the concentration is 40 g / L, the endpoint pH value of the nickel-cobalt precipitation treatment is 7.6, wherein the components of the nickel-cobalt precipitation slag include: 39.80% Mg, 0.093% Ni and 0.017% Co.

[0040] In order to achieve the corresponding end point pH value of nickel-cobalt precipitation treatment above 7, the pH value will not rise rapidly with the addition of neutralizer during the nickel-cobalt precipitation process, and the Mg ion concentration in the magnesium chloride-containing liquid will drop significantly, resulting in a large amount of nickel-cobalt slag and a high Mg content in the nickel-cobalt slag, which in turn leads to low Ni and Co content, reducing the economic value of the nickel-cobalt slag. 2+ When the concentration is below 52 g / L (including 52 g / L), the concentration of Ni and Co ions in the solution after nickel-cobalt precipitation can be below 5 mg / L, and the Ni grade in the nickel-cobalt precipitation slag can be above 10%.

[0041] In a preferred embodiment, before the magnesium-containing mineral is mixed with the first hydrochloric acid, the magnesium-containing mineral is subjected to grinding and magnetic separation treatment in sequence. The present invention can improve the leaching efficiency and the purity of SiO2 in silicon slag by grinding and magnetic separation treatment of the magnesium-containing mineral. The magnesium-containing mineral can improve the leaching efficiency by grinding treatment, and the magnesium-containing mineral can screen and separate magnetic substances by magnetic separation treatment to avoid mixing with the insoluble SiO2 in the magnesium-containing mineral after acid leaching treatment. Preferably, the particle size of the magnesium-containing mineral after grinding is 80 to 250 mesh. Preferably, the intensity of magnetic separation is 150 to 250 ka / m.

[0042] In order to further improve the leaching efficiency of metal elements, the second leaching treatment is preferably heated by steam, and the pressure of the saturated steam is 0.1-0.4 MPa. Steam heating has high heating efficiency, saves energy, and has a simple equipment structure. In order to further reduce production energy consumption, the second leaching filtrate is preferably used as a heat source for the first leaching treatment.

[0043] In an optional embodiment, the magnesium chloride-containing liquid is added to a decalcifying agent for decalcification, and then evaporated and crystallized to obtain magnesium chloride hexahydrate; and the magnesium chloride hexahydrate is then thermally decomposed to obtain magnesium oxide and hydrochloric acid. The present invention is based on the operation of two-stage acid leaching treatment, iron and aluminum precipitation treatment, and nickel and cobalt precipitation treatment, and obtains a magnesium chloride-containing liquid with a high magnesium recovery rate. The magnesium chloride-containing liquid can be recovered by evaporation, crystallization, and thermal decomposition to obtain magnesium oxide and hydrochloric acid. The hydrochloric acid can be recycled as an acid leaching agent, and the magnesium oxide can be used as a neutralizing agent, which further reduces the production cost of magnesium-containing mineral processing.

[0044] The present application is further described in detail below in conjunction with specific examples, which should not be construed as limiting the scope of protection claimed in the present application. In the examples, serpentine is used as an example for testing.

[0045] Example 1

[0046] The main components of serpentine are: Si: 19.2%, Mg: 26.39%, Fe: 4.01, Al: 0.19%, Co: 0.036%, Ni: 0.23%, Ca: 0.4%.

[0047] Serpentine is subjected to grinding and magnetic separation (magnetic separation intensity is 200ka / m), and the particle size of the product after grinding is more than 90% of 150 mesh; under normal pressure, the serpentine is mixed with hydrochloric acid solution (37%) and water for the first leaching treatment (temperature is 85°C, time is 2h, liquid-solid ratio is 3.7), and the concentration of hydrochloric acid in the system after the first leaching treatment is 9.31g / L, and the product is filtered to obtain the first leaching filtrate and the first leaching residue. The first leaching filtrate includes Mg: 62670mg / L, Fe: 6070.20mg / L, Al: 209mg / L, Ni: 339.4mg / L, and Co: 50.72mg / L.

[0048] The first leaching filtrate was treated with iron and aluminum precipitation (temperature 80°C, time 5h, aeration, pH value adjusted to 4.8 with MgO slurry), and then filtered to obtain iron and aluminum removal liquid and iron and aluminum slag. The iron and aluminum removal liquid includes Al: 1.20mg / L, Fe: 0.5mg / L, Ni: 299.6mg / L, Co: 46.14mg / L, Mg: 63141mg / L.

[0049] The Mg ion concentration of the de-iron and de-aluminum solution is diluted to 45000 mg / L, and the diluted de-iron and de-aluminum solution is subjected to nickel and cobalt precipitation treatment (temperature is 90°C, time is 5 hours, neutralizing agent is MgO, MgO dosage coefficient per liter of solution is 1.91 g / L, and end point pH value is 7.26), and after filtration, nickel and cobalt precipitation slag and magnesium chloride-containing solution are obtained. Among them, the magnesium chloride-containing solution includes Ni: 1.5 mg / L, Co: 0.02 mg / L, Mg: 44.92 g / L; the nickel and cobalt slag grade is: Ni: 12.1%, Mg: 26.4%, Co: 1.21%.

[0050] The magnesium chloride-containing liquid is passed through CO2 to remove calcium, and then evaporated and crystallized to obtain magnesium chloride hexahydrate, which is then thermally decomposed to obtain magnesium oxide and hydrochloric acid.

[0051] Under normal pressure, the first leaching residue was mixed with a hydrochloric acid solution (37%) and water for a second leaching treatment (temperature of 95°C, time of 3h, liquid-to-solid ratio of 6.6). After the second leaching treatment, the concentration of hydrochloric acid in the system was 68.31g / L. The products were separated to obtain a second leaching filtrate and a second leaching residue. The second leaching filtrate was returned to the first leaching treatment, and the second leaching residue was slurried, washed, filtered, and dried to obtain silicon slag.

[0052] The composition of silicon slag is: Fe: 0.09%, Al: 0.04%, Ca: 0.03%, Si: 42.9%, Mg: 1.24%, which meets the requirements for the main impurities of serpentine leaching slag for the preparation of industrial silicon (Si4410) ("Requirements for the Chemical Composition of Serpentine Leaching Slag for the Preparation of Industrial Silicon").

[0053] pass Figure 4 Phase identification showed that the main phases of nickel-cobalt slag were Mg(OH)2 and a small amount of Mg2(OH)ClCO3·3H2O.

[0054] Example 2

[0055] The main components of serpentine are: Si: 19.4%, Mg: 24.45%, Fe: 3.29, Al: 0.41%, Co: 0.069%, Ni: 0.31%, Ca: 0.24%.

[0056] The serpentine was subjected to grinding and magnetic separation (magnetic separation intensity was 200ka / m), and the particle size of the product after grinding was more than 90% of 150 mesh; under normal pressure, the serpentine was mixed with hydrochloric acid solution (37%) and water for the first leaching treatment (temperature was 95°C, time was 3h, liquid-solid ratio was 3.7), and the concentration of hydrochloric acid in the system after the first leaching treatment was 8.76g / L, and the product was filtered to obtain the first leaching filtrate and the first leaching residue.

[0057] Among them, the first leaching filtrate includes Mg: 59601 mg / L, Fe: 6873.69 mg / L, Al: 416 mg / L, Ni: 491.3 mg / L, and Co: 62.20 mg / L.

[0058] The first leaching filtrate was treated with iron and aluminum precipitation (temperature 80°C, time 5h, aeration, pH value adjusted to 4.6 with MgO slurry), and then filtered to obtain iron and aluminum removal liquid and iron and aluminum slag. The iron and aluminum removal liquid includes Al: 3.01mg / L, Fe: 0.9mg / L, Ni: 489.2mg / L, Co: 56.14mg / L, Mg: 59003mg / L.

[0059] The Mg ion concentration of the de-iron and de-aluminum solution was diluted to 50000 mg / L, and the diluted de-iron and de-aluminum solution was treated with nickel and cobalt precipitation (temperature 80°C, time 6 hours, neutralizing agent MgO, MgO dosage coefficient per liter of solution 2.02 g / L, end point pH value 7.19), and after filtration, nickel and cobalt precipitation slag and magnesium chloride-containing solution were obtained. Among them, Ni: 3.8 mg / L, Co: 0.05 mg / L, Mg: 49.90 g / L; nickel and cobalt slag grade: Ni: 14.1%, Mg: 24.4%, Co: 1.95%.

[0060] The magnesium chloride-containing liquid is passed through CO2 to remove calcium, and then evaporated and crystallized to obtain magnesium chloride hexahydrate, which is then thermally decomposed to obtain magnesium oxide and hydrochloric acid.

[0061] Under normal pressure, the first leaching residue is mixed with hydrochloric acid solution (37%) and water for the second leaching condition: temperature is 95°C, time is 3h, liquid-to-solid ratio is 3.7, the concentration of hydrochloric acid in the system after the second leaching treatment is 79.3g / L, and the product is separated to obtain the second leaching filtrate and the second leaching residue. The second leaching filtrate is returned to the first leaching treatment, and the second leaching residue is slurried, washed, filtered and dried to obtain silicon slag.

[0062] The Ni and Co leaching rates of serpentine are ≥99%, the Mg leaching rate is ≥99%, and the Fe leaching rate is ≥97%.

[0063] The final silicon slag composition is: Fe: 0.31%, Al: 0.03%, Ca: 0.017%, Si: 40.9%, Mg: 1.94%. The silicon slag can be used as raw material for preparing industrial silicon after further processing.

[0064] Example 3

[0065] The main components of serpentine are: Si: 17.6%, Mg: 26.39%, Fe: 4.01, Al: 0.19%, Co: 0.036%, Ni: 0.23%, Ca: 0.4%.

[0066] The serpentine was subjected to grinding and magnetic separation (magnetic separation intensity was 200ka / m), and the particle size of the product after grinding was more than 90% of 150 mesh; under normal pressure, the serpentine was mixed with hydrochloric acid solution (37%) and water for the first leaching treatment (temperature was 85°C, time was 2h, liquid-solid ratio was 3.7), and the concentration of hydrochloric acid in the system after the first leaching treatment was 9.31g / L, and the product was filtered to obtain the first leaching filtrate and the first leaching residue.

[0067] Among them, the first leaching filtrate includes Mg: 62670 mg / L, Fe: 6070.20 mg / L, Al: 209 mg / L, Ni: 339.4 mg / L, and Co: 50.72 mg / L.

[0068] The first leaching filtrate was treated with iron and aluminum precipitation (temperature 80°C, time 5h, aeration, pH value adjusted to 4.6 with MgO slurry), and then filtered to obtain iron and aluminum removal liquid and iron and aluminum slag. The iron and aluminum removal liquid includes Al: 3.01mg / L, Fe: 0.9mg / L, Ni: 489.2mg / L, Co: 56.14mg / L, Mg: 59003mg / L.

[0069] The Mg ion concentration of the de-iron and de-aluminum solution was diluted to 51000 mg / L, and the diluted de-iron and de-aluminum solution was treated with nickel and cobalt precipitation (temperature 70°C, time 6 hours, neutralizing agent MgO, MgO dosage coefficient per liter of solution 1.97 g / L, end point pH value 7.09), and after filtration, nickel and cobalt precipitation slag and magnesium chloride-containing solution were obtained. Among them, Ni: 4.2 mg / L, Co: 0.04 mg / L, Mg: 50.79 g / L; nickel and cobalt slag grade: Ni: 11.1%, Mg: 25.2%, Co: 1.17%.

[0070] The magnesium chloride-containing liquid is passed through CO2 to remove calcium, and then evaporated and crystallized to obtain magnesium chloride hexahydrate, which is then thermally decomposed to obtain magnesium oxide and hydrochloric acid.

[0071] Under normal pressure, the first leaching residue was mixed with a hydrochloric acid solution (37%) and water for a second leaching treatment (temperature of 95°C, time of 3h, liquid-to-solid ratio of 6.6). After the second leaching treatment, the concentration of hydrochloric acid in the system was 68.31g / L. The products were separated to obtain a second leaching filtrate and a second leaching residue. The second leaching filtrate was returned to the first leaching treatment, and the second leaching residue was slurried, washed, filtered, and dried to obtain silicon slag.

[0072] The Ni and Co leaching rates of serpentine are ≥99%, the Mg leaching rate is ≥98%, and the Fe leaching rate is ≥99%.

[0073] The final silicon slag composition: Fe: 0.09%, Al: 0.04%, Ca: 0.03%, Si: 42.9%, Mg: 1.24%. The composition meets the requirements for the main impurities of serpentine leaching slag for the preparation of industrial silicon (Si4410) ("Chemical Composition Requirements for Serpentine Leaching Slag for the Preparation of Industrial Silicon").

[0074] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for treating magnesium-containing minerals, characterized in that: The following steps are involved: The magnesium-containing mineral is mixed with a first hydrochloric acid to perform a first leaching treatment, and the product is subjected to solid-liquid separation to obtain a first leaching filtrate and a first leaching residue; The first leaching filtrate is treated with a first neutralizing agent to precipitate iron and aluminum, and the product is subjected to solid-liquid separation to obtain a liquid after iron and aluminum removal and iron-aluminum slag; The iron- and aluminum-removed liquid is treated with a second neutralizing agent to precipitate nickel and cobalt, and the product is subjected to solid-liquid separation to obtain nickel-cobalt slag and a liquid containing magnesium chloride; The first leaching residue is mixed with a second hydrochloric acid for a second leaching treatment, and the product is subjected to solid-liquid separation to obtain a second leaching filtrate and a second leaching residue; the second leaching filtrate is returned to the mixture of the magnesium-containing mineral and the first hydrochloric acid for the first leaching treatment; The second leaching residue is sequentially subjected to slurry washing, filtering and drying to obtain silicon slag.

2. The method for treating magnesium-containing minerals according to claim 1, characterized in that: The temperature of the first leaching treatment is 50-105°C and the time is 0.5-20h; Preferably, the hydrochloric acid concentration of the system after the first leaching treatment is 5 to 30 g / L.

3. The method for treating magnesium-containing minerals according to claim 1 or 2, characterized in that: The temperature of the second leaching treatment is 50-105°C and the time is 0.5-20h; Preferably, the hydrochloric acid concentration of the system after the second leaching treatment is 40-120 g / L.

4. The method for treating magnesium-containing minerals according to any one of claims 1 to 3, characterized in that: The first neutralizing agent and the second neutralizing agent are each independently selected from one or more of MgO, MgCO3, NaOH, Mg, Ca(OH)2 or CaO.

5. The method for treating magnesium-containing minerals according to any one of claims 1 to 4, characterized in that: The pH value of the iron and aluminum precipitation treatment is 3 to 5; Preferably, the temperature of the iron-aluminum precipitation treatment is 50-100° C. and the time is 0.5-20 hours.

6. The method for treating magnesium-containing minerals according to any one of claims 1 to 5, characterized in that: The Mg in the liquid after iron and aluminum removal 2+ Concentration ≤52g / L.

7. The method for treating magnesium-containing minerals according to any one of claims 1 to 6, characterized in that: The endpoint pH value of the system after the nickel-cobalt precipitation treatment is greater than 7.0; Preferably, the nickel-cobalt precipitation treatment is carried out at a temperature of 30 to 100° C. and for a time of 0.5 to 20 hours.

8. The method for treating magnesium-containing minerals according to any one of claims 1 to 7, characterized in that: Before the magnesium-containing mineral is mixed with the first hydrochloric acid, the magnesium-containing mineral is subjected to grinding and magnetic separation treatments in sequence; Preferably, the particle size of the magnesium-containing mineral after grinding is 80 to 250 mesh; Preferably, the intensity of the magnetic separation is 150-250 ka / m.

9. The method for treating magnesium-containing minerals according to any one of claims 1 to 8, characterized in that: The heating method of the second leaching treatment is steam heating, and the pressure of the saturated steam is 0.1-0.4 MPa.

10. The method for treating magnesium-containing minerals according to any one of claims 1 to 9, characterized in that: The magnesium chloride-containing liquid is added with a decalcifying agent to remove calcium, and then evaporated and crystallized to obtain magnesium chloride hexahydrate; and the magnesium chloride hexahydrate is thermally decomposed to obtain magnesium oxide and hydrochloric acid; Preferably, the decalcifying agent is selected from CO2; Preferably, the magnesium-containing mineral comprises serpentine, magnesite or dolomite; Preferably, after the magnesium-containing mineral is mixed with the first hydrochloric acid to undergo the first leaching treatment, the first leaching filtrate contains magnesium ions, chloride ions, iron ions and nickel ions.

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