Method for preparing refined water glass and magnesium salt from serpentine-containing mineral raw material and application of refined water glass and magnesium salt

Abstract

The invention provides a method for preparing refined water glass and magnesium salt from a serpentine-containing mineral raw material and application of the serpentine-containing mineral raw material, and the method comprises the following steps: processing the serpentine-containing mineral raw material into serpentine-containing mineral powder, uniformly mixing the serpentine-containing mineral powder with a reaction aid according to a ratio, and then carrying out reduction roasting treatment to obtain a roasting reaction product; the roasting reaction product is placed in the leaching solution I for a leaching reaction I, after the leaching reaction is finished, filtering and washing are conducted, filtrate I and filter residues I are obtained, and the filtrate I is refined water glass; and placing the filter residue I in the leaching solution II to carry out a leaching reaction II, filtering and washing after the leaching reaction II is finished to obtain a filtrate II and a filter residue II, and carrying out post-treatment on the filtrate II to obtain the refined magnesium salt. According to the method, the serpentine-containing mineral raw materials and the auxiliaries are mixed and roasted to obtain the leaching product, then the refined sodium silicate and the refined magnesium salt are obtained through selective leaching, the tailings can be used as steel smelting raw materials, all-component resource utilization of tailings-free solid waste is achieved, and meanwhile the method has the significance of resource utilization and ecological and sustainable development.

Description

Technical Field

[0001] The invention relates to the technical field of extracting valuable components from asbestos tailings, and in particular to a method for preparing refined water glass and magnesium salts from serpentine-containing mineral raw materials and applications thereof. Background Art

[0002] In modern industrial production, the demand for high-purity silicon and magnesium compounds continues to rise, but traditional preparation processes have numerous drawbacks. The production of water glass from silicon-containing raw materials faces challenges with low silicon extraction rates and difficulty increasing purity. The refining process is complex and costly, and the product is prone to impurities that affect quality. The production of magnesium salts relies on magnesium ore, but purification efficiency is low and impurity levels are difficult to control, making it unable to meet market demand for high-purity magnesium salts.

[0003] Serpentine-containing raw materials, such as serpentinite, serpentine mines, and chrysotile asbestos mines, produce large amounts of stripping waste rock and beneficiation tailings during the mining and beneficiation process. Most of these wastes contain a certain amount of silicon and magnesium components, but have long been poorly utilized. They not only occupy land resources but also pose potential environmental pollution, resulting in a significant waste of resources. Furthermore, if improperly handled, harmful substances in the tailings, such as chromium and iron, pose a threat to the ecological environment. Furthermore, these wastes often contain minerals such as chlorite and talc, which have strong internal chemical bonds and highly stable structures. Conventional acid or alkaline leaching processes make it difficult to effectively dissociate the silicon and magnesium components, resulting in generally low extraction rates for silica and magnesium ions.

[0004] Cr2O3, often present in serpentine-containing mineral raw materials, is easily converted to soluble hexavalent chromium under oxidizing conditions and subsequently leached out. Furthermore, existing magnesium extraction processes often require elevated temperatures and strong acid conditions for magnesium ion extraction, leading to the co-dissolution of impurities such as iron and aluminum. This complicates the subsequent impurity removal process and poses a significant risk of secondary pollution from the impurity removal tailings.

[0005] Based on this, many researchers have tried to improve the process to solve the above problems. For example, Chinese patent CN116081659 uses asbestos tailings as raw materials and adopts ammonium sulfate roasting method to prepare refined magnesium sulfate solution in one step, but this method has little damage to talc and chlorite, resulting in limited application range. For another example, Chinese patent CN105502426 uses strong alkali roasting to extract silicon dioxide in chrysotile asbestos tailings, but does not take into account the co-dissolution of impurity ions and subsequent impurity removal and purification problems. Although these prior arts have improved, they still have many defects and fail to fundamentally solve the efficient utilization and environmental problems of serpentine-containing mineral raw materials.

[0006] Based on the above background, the present invention aims to provide a method for efficiently preparing refined water glass and refined magnesium salts in one step from serpentine-containing mineral raw materials, and realizing resource utilization of all components of solid waste, so as to overcome the defects and shortcomings of the existing technology, meet the market demand for high-purity silicon and magnesium compounds, solve the problem of waste disposal, and promote the sustainable development of resources and the environment. Summary of the Invention

[0007] The present invention aims to address at least one of the aforementioned deficiencies in the prior art. For example, one object of the present invention is to provide a method for preparing refined water glass and magnesium salt from serpentine-containing mineral raw materials; a second object of the present invention is to provide refined water glass and applications of refined water glass; and a third object of the present invention is to provide refined magnesium salt and applications of refined magnesium salt.

[0008] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing refined water glass and magnesium salt from a serpentine-containing mineral raw material, the method comprising: 1) processing the serpentine-containing mineral raw material into a serpentine-containing ore powder, and mixing it with a reaction aid in a proportion and then performing a reduction roasting treatment to obtain a roasting reaction product; 2) placing the roasting reaction product in a leaching solution I for leaching reaction I, filtering and rinsing after completion to obtain a filtrate I and a filter residue I, wherein the filtrate I is refined water glass; 3) placing the filter residue I in a leaching solution II for leaching reaction II, filtering and rinsing after completion to obtain a filtrate II and a filter residue II, and post-treating the filtrate II to obtain a refined magnesium salt.

[0009] Optionally, the chemical composition of the serpentine-containing mineral raw material includes, by mass percentage, 37.0% to 42.0% SiO2, 36.0% to 42.0% MgO, 0.8% to 1.2% Al2O3, 3.0% to 8.0% TFe2O3, 0.4% to 0.7% CaO, 0.4% to 0.7% Cr2O3, 0.1% to 0.3% NiO, and 0.0% to 0.5% other impurity oxides; the loss on ignition is 11.0% to 13.5%; the serpentine-containing mineral raw material includes stripping waste rock and mineral processing tailings generated during the mining and beneficiation of serpentine and serpentine mines and chrysotile asbestos mines, the main mineral type is serpentine, and also includes one or more of talc, magnesite, magnetite, brucite, chlorite and quartz.

[0010] Optionally, the reaction aid includes one or both of sodium hydroxide and potassium hydroxide; the mixing ratio is such that the molar ratio of the reaction aid to SiO2 in the serpentine-containing mineral powder is 3.0 to 4.0.

[0011] Optionally, the reduction roasting treatment is carried out in a closed high-temperature roasting furnace; the conditions for the reduction roasting treatment are adding a carbonaceous reducing agent and / or continuously introducing carbon monoxide into the closed roasting furnace; the temperature of the reduction roasting treatment is 700°C to 800°C, and the time of the reduction roasting treatment is 60min to 120min.

[0012] Optionally, the leaching solution I is one of industrial pure water or an aqueous solution containing sodium hydroxide / potassium hydroxide with a pH value of 7.5 to 9. The equipment for the leaching reaction I includes an alkali-resistant reactor with a stirring and heating device; the solid-liquid ratio of the roasting reaction product to the leaching solution I in the leaching reaction I is 100 to 200 g / L; the temperature of the leaching reaction I is 70° C. to 90° C., and the time is 30 min to 90 min.

[0013] Optionally, in the leaching reaction I, the SiO2 leaching rate is 85.0% to 95.0%, the chromium ion leaching rate is 0.5% to 1.5%, and the iron ion leaching rate is 0.1% to 2.0%.

[0014] Optionally, the leaching solution II is one of sulfuric acid and hydrochloric acid solutions, with an initial pH value of 4.0 to 5.0, and the pH value is controlled to be stable within the initial value range during the reaction; the equipment for the leaching reaction II includes an acid-resistant reactor with a stirring and heating device; the solid-liquid ratio of the leaching solution II to the filter residue I is 100 to 200 g / L; the temperature of the leaching reaction II is 15° C. to 30° C., and the time is 60 min to 120 min.

[0015] Alternatively, the Mg in the leaching reaction II 2+ The leaching rate of iron ions is 78.0% to 90.0%, and the leaching rate of iron ions is 0.8% to 1.5%.

[0016] A second aspect of the present invention provides a refined water glass and an application of the refined water glass.

[0017] Optionally, the mass concentration of SiO2 in the water glass is 31.5g / L to 79.8g / L, and the purity of SiO2 is 99.80% to 99.95%;

[0018] The refined water glass is prepared by the following method: 1) processing a serpentine-containing mineral raw material into a serpentine-containing ore powder, uniformly mixing the ore powder with a reaction aid in a certain proportion, and then performing a reduction roasting treatment to obtain a roasting reaction product; 2) placing the roasting reaction product in a leaching liquid I to perform a leaching reaction I, and after the leaching reaction is completed, filtering and rinsing to obtain a filtrate I and a filter residue I, wherein the filtrate I is the refined water glass.

[0019] Optionally, the application of the refined water glass includes: application in the preparation of high-purity silicon-containing compound products, or application in the preparation of solid water glass.

[0020] Wherein, the refined water glass is evaporated and dried to obtain solid water glass.

[0021] A third aspect of the present invention provides a refined magnesium salt and an application of the refined magnesium salt.

[0022] Alternatively, the refined magnesium salt is prepared by the preparation method described in the first aspect;

[0023] Mg in the refined magnesium salt 2+ The mass concentration is 11.34g / L~24.50g / L.

[0024] Optionally, the application of the refined magnesium salt includes: application in the preparation of high-purity magnesium-containing compound products, or application in the preparation of magnesium salt powder.

[0025] The refined magnesium salt is evaporated and dried to obtain magnesium salt powder, and the mass percentage of MgSO4 and MgCl2 contained in the magnesium salt powder is 98.80% to 99.50%.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) The present invention uses alkali as a roasting reaction aid, which can effectively destroy the mineral structures of serpentine, talc, chlorite, etc., and the extraction rate of silicon dioxide is as high as 85.0% to 95.0%. The purity of SiO2 in the refined water glass product can reach 99.80% to 99.95%.

[0028] (2) By controlling the roasting conditions, the present invention suppresses the oxidation reaction of chromium in a reducing atmosphere, maintaining the chromium ion as trivalent chromium. Furthermore, during the water leaching process, due to the alkaline environment of the solution, the chromium leaching rate remains extremely low, at only 0.5% to 1.5%. This effectively reduces the risk of chromium entering the water glass and the resulting heavy metal contamination.

[0029] (3) The present invention selectively extracts magnesium ions by controlling the leaching conditions. 2+ The leaching rate is as high as 78.0% to 90.0%, and the purity of the magnesium salt can reach 98.80% to 99.50%. Directly obtaining the refined magnesium salt reduces the impurity removal process steps and the generation of impurity removal slag.

[0030] (4) The present invention mixes serpentine-containing mineral raw materials with auxiliary agents and roasts them to obtain products that can be selectively leached in steps, and obtains refined water glass and refined magnesium salt respectively through the selective leaching steps. The tailings can be used as raw materials for steel smelting, thereby realizing the resource utilization of all components of solid waste without tailings discharge, which has important significance for resource and environmental protection and ecological and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and other objects and / or features of the present invention will become more apparent from the following description in conjunction with the accompanying drawings, in which:

[0032] Figure 1 A flow chart of the preparation method of the present invention is shown.

[0033] Figure 2 The XRD patterns of Cr2O3 alkali calcined products under aerobic and anaerobic conditions are shown.

[0034] Figure 3 The XRD patterns of the alkali roasted slag and water leaching slag of the serpentine-containing mineral raw material prepared by the method of the present invention are shown.

[0035] Explanation of the main reference numerals: Cr2O3-O2 represents aerobic conditions, and Cr2O3-N2 represents reducing conditions;

[0036] NB-750℃-M4.0 is roasted slag, and NS-750℃-M4.0 is water-leached slag. DETAILED DESCRIPTION

[0037] Hereinafter, the method for preparing refined water glass and magnesium salt from serpentine-containing mineral raw materials and its application will be described in detail with reference to exemplary embodiments.

[0038] The principle of the present invention is that the serpentine-containing mineral powder first decomposes at high temperature during alkaline roasting in a reducing atmosphere, and the silicon dioxide component therein reacts with NaOH to generate Na4SiO4. The silicon dioxide component and the magnesium oxide component also generate soluble Na2MgSiO4 under the condition of sodium hydroxide roasting. The SiO2 in Na2MgSiO4 and Na4SiO4 can be extracted by water leaching.

[0039] SiO2+4NaOH=Na4SiO4+2H2O,

[0040] SiO2+4NaOH+2MgO+SiO2=2Na2MgSiO4+2H2O,

[0041] Under reducing conditions, the oxidation reaction of Cr can be effectively inhibited, so that Cr remains trivalent; during the water immersion process, due to the residual alkali, the water immersion system is alkaline, and trivalent Cr is re-precipitated as Cr(OH)3.

[0042] Cr2O3+2NaOH=2NaCrO2+H2O,

[0043] Under reducing conditions, the iron ions can be inhibited from forming sodium ferrite which is easily soluble in water, so that the iron ions remain in the water-leached residue in the form of hematite.

[0044] By controlling the reduction roasting conditions, chromium ions and iron ions are retained in the filter residue, and high-purity water glass is prepared in one step.

[0045] Since different metal ions have different dissolution pH values, the pH value of the leaching process is controlled to inhibit the leaching of iron ions and selectively leach magnesium ions, thereby preparing refined magnesium salt in one step.

[0046] Exemplary embodiment 1

[0047] This exemplary embodiment provides a method for preparing refined water glass and magnesium salt from serpentine-containing mineral raw materials, the method may include:

[0048] S1. Processing the serpentine-containing mineral raw material into serpentine-containing mineral powder, uniformly mixing the raw material with a reaction aid, and then performing reduction roasting treatment to obtain a roasting reaction product.

[0049] In this embodiment, the chemical composition of the serpentine-containing mineral raw material includes, by mass percentage, 37.0% to 42.0% SiO2, 36.0% to 42.0% MgO, 0.8% to 1.2% Al2O3, 3.0% to 8.0% TFe2O3, 0.4% to 0.7% CaO, 0.4% to 0.7% Cr2O3, 0.1% to 0.3% NiO, and 0.0% to 0.5% other impurity oxides; the loss on ignition is 11.0% to 13.5%; the serpentine-containing mineral raw material includes stripping waste rock and mineral processing tailings generated during the mining and beneficiation of serpentine and serpentine mines and chrysotile asbestos mines, and the main mineral type is serpentine, and also includes one or more of talc, magnesite, magnetite, brucite, chlorite and quartz.

[0050] In this embodiment, the reaction aid includes one or both of sodium hydroxide and potassium hydroxide; the ratio is based on a molar ratio of the reaction aid to SiO2 in the serpentine-containing mineral powder of 3.0 to 4.0, such as 3.1, 3.3, 3.5 and 3.9.

[0051] Among them, if too much additive is added, it will cause waste of resources, and if too little additive is added, it will lead to incomplete reaction and low silica leaching rate.

[0052] In this embodiment, the reduction roasting treatment is carried out in a closed high-temperature roasting furnace; the conditions for the reduction roasting treatment are adding a carbonaceous reducing agent and / or continuously introducing carbon monoxide into the closed roasting furnace; the temperature of the reduction roasting treatment is 700°C to 800°C, for example, 700°C, 730°C, 750°C and 790°C, etc.

[0053] Among them, when the roasting temperature is too low, the reaction between sodium hydroxide and serpentine in asbestos tailings is incomplete, and the silica leaching rate is low. When the roasting temperature is too high, the energy consumption is high, so 700℃~800℃ is selected.

[0054] In this embodiment, the reduction roasting treatment time is 60 min to 120 min, for example, 61 min, 90 min, 110 min, and 115 min.

[0055] Among them, when the roasting time is too short, the reaction between the additive and the serpentine in the asbestos tailings will be incomplete, reducing the extraction rate of silica; when the roasting time is too long, the energy consumption will increase, which is not economical.

[0056] In this embodiment, the roasting reaction product mainly includes sodium / potassium magnesium silicate, sodium / potassium silicate, periclase, magmasite, and a small amount of one or more of sodium / potassium chromate and chromium / nickel iron ore.

[0057] S2. placing the roasting reaction product in leaching liquid I to carry out leaching reaction I. After completion, filtering and rinsing to obtain filtrate I and filter residue I, wherein the filtrate I is refined water glass.

[0058] In this embodiment, the leaching solution I is one of industrial pure water or an aqueous solution containing sodium hydroxide / potassium hydroxide with a pH value of 7.5 to 9, and the equipment for the leaching reaction I includes an alkali-resistant reactor with a stirring and heating device.

[0059] In this embodiment, the solid-liquid ratio of the roasting reaction product to the leachate I in the leaching reaction I is 100-200 g / L, for example, 105 mL / g, 125 mL / g, 150 mL / g and 195 mL / g; a large solid-liquid ratio will result in a low silica leaching rate, and a small solid-liquid ratio will result in a reduced silica concentration in the water glass.

[0060] In this embodiment, the temperature of the leaching reaction I is 70°C to 90°C, such as 71°C, 82°C, 85°C, and 89°C. A temperature that is too low will result in an incomplete reaction and a low silica leaching rate. The time of the leaching reaction I is 30 minutes to 90 minutes, such as 31 minutes, 45 minutes, 70 minutes, and 89 minutes. A reaction time that is too short will result in an incomplete reaction, while a reaction time that is too long will increase time costs.

[0061] In this embodiment, the SiO2 leaching rate in the leaching reaction I is 85.0% to 95.0%, the chromium ion leaching rate is 0.5% to 1.5%, and the iron ion leaching rate is 0.1% to 2.0%; the filter residue I mainly contains one or more of periclase, hematite, magnesium hydroxide, and a small amount of chromium hydroxide / nickel.

[0062] S3, placing the filter residue I in the leaching liquid II to carry out leaching reaction II, filtering and rinsing after the end to obtain filtrate II and filter residue II, and post-treating the filtrate II to obtain refined magnesium salt.

[0063] In this embodiment, the leaching solution II is a solution of sulfuric acid and hydrochloric acid, with an initial pH value of 4.0 to 5.0. During the reaction, the pH value is controlled to be stable within the initial value range; if the pH of the reaction system is too high, the Mg2+ leaching rate will be too low, and if the pH is too low, impurity ions such as iron ions will be dissolved together.

[0064] In this embodiment, the equipment for the leaching reaction II includes an acid-resistant reactor with a stirring and heating device; the solid-liquid ratio of the leaching solution II to the filter residue I is 100-200 g / L, for example, 110 g / L, 120 g / L, 140 g / L and 195 g / L; too high a solid-liquid ratio will result in a low magnesium ion leaching rate, and too high a solid-liquid ratio will result in increased energy consumption.

[0065] In this embodiment, the temperature of the leaching reaction II is 15°C to 30°C, such as 15°C, 18°C, 20°C, and 29°C. Increased temperature will lead to increased energy consumption. The duration of the leaching reaction II is 60 min to 120 min, such as 61 min, 80 min, 90 min, and 115 min. If the leaching time is too short, the magnesium ion leaching will be incomplete, and if the leaching time is too long, the energy consumption will increase.

[0066] In this embodiment, the Mg in the leaching reaction II 2+ The leaching rate is 78.0% to 90.0%, and the iron ion leaching rate is 0.8% to 1.5%; the filter residue II mainly contains iron, chromium, and nickel oxides and can be used as raw material for steel smelting.

[0067] Exemplary embodiment 2

[0068] The present exemplary embodiment provides a purified water glass and an application of the purified water glass.

[0069] In this embodiment, the SiO2 mass concentration in the refined water glass is 31.5 g / L~79.8 g / L, and the SiO2 purity is 99.80%~99.95%; the refined water glass can be prepared by the following method: 1) processing the serpentine-containing mineral raw material into serpentine-containing mineral powder, and mixing it with the reaction auxiliary agent in a proportion and then performing reduction roasting treatment to obtain a roasting reaction product; 2) placing the roasting reaction product in the leaching liquid I to carry out the leaching reaction I, and after the end, filtering and rinsing to obtain the filtrate I and the filter residue I, the filtrate I is the refined water glass.

[0070] In this embodiment, the application of the refined water glass may include: application in the preparation of high-purity silicon-containing compound products, or application in the preparation of solid water glass.

[0071] Wherein, the refined water glass is evaporated and dried to obtain solid water glass.

[0072] Exemplary Embodiment 3

[0073] This exemplary embodiment provides a refined magnesium salt and an application of the refined magnesium salt. The refined magnesium salt can be prepared by the preparation method described in exemplary embodiment 1.

[0074] In this embodiment, the Mg in the refined magnesium salt is 2+ The mass concentration is 11.34g / L~24.50g / L.

[0075] In this embodiment, the application of the refined magnesium salt includes: application in the preparation of high-purity magnesium-containing compound products, or application in the preparation of magnesium salt powder.

[0076] The refined magnesium salt is evaporated and dried to obtain magnesium salt powder, and the mass percentage of MgSO4 and MgCl2 contained in the magnesium salt powder is 98.80% to 99.50%.

[0077] In order to better understand the above exemplary embodiments of the present invention, they are further described below with reference to specific examples.

[0078] Example 1

[0079] The process of preparing refined water glass and magnesium salt from serpentine mineral raw materials is as follows: Figure 1 The serpentine-containing mineral raw material selected for the test is Aksai asbestos tailings, which mainly contains serpentine, a small amount of talc, magnetite and quartz. The main chemical composition is shown in Table 1:

[0080] Table 1 Main chemical components of asbestos tailings

[0081] element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[TFe2O3]]> MgO CaO Loss on ignition other <![CDATA[Content w B / %]]> 40.33 1.20 3.09 41.59 0.47 12.74 0.48

[0082] S1. Processing the Aksai asbestos tailings into mineral powder with a particle size of less than 100 mesh, mixing sodium hydroxide and the mineral powder at a molar ratio of sodium hydroxide to silicon dioxide in the mineral powder of 3.0, placing the mixture in a sealed high-temperature furnace into which carbon monoxide is continuously introduced, and roasting the mixture at a temperature of 700° C. for 60 minutes to obtain a roasting reaction product, wherein the roasting reaction product mainly contains sodium magnesium silicate, sodium silicate, magnesium oxide, hematite, and sodium chromate.

[0083] S2. The roasting reaction product was placed in a reactor filled with industrial pure water and equipped with a stirring and heating device for leaching. The leaching reaction was performed at a liquid-to-solid ratio of 100 g / L, a temperature of 70°C, and a time of 30 minutes. After the leaching was completed, the leached product was filtered to obtain a filter residue I and a filtrate I. The filter residue I mainly contained periclase, maghemite, magnesium hydroxide, and chromium hydroxide. The filtrate I was refined water glass with a SiO2 concentration of 31.5 g / L and a SiO2 purity of 99.80%. The silica leaching rate was 85.0%, the chromium ion leaching rate was only 0.5%, and the iron ion leaching rate was 2.0%.

[0084] S3, the filter residue I was placed in a hydrochloric acid solution with a pH value of 4.0 for leaching, the leaching solid-liquid ratio was 100g / L, the leaching temperature was 15°C, and the leaching time was 60min. After the leaching was completed, the filtrate II and the filter residue II were obtained by filtration and rinsing. Mg 2+ The leaching rate was 78.0%, the iron ion leaching rate was 0.8%; the Mg content in the filtrate was 2+ The mass concentration is 11.34 g / L. After evaporation and drying, magnesium chloride powder is obtained, in which the mass percentage of MgCl2 in the magnesium chloride powder is 98.80%. Filter residue II mainly contains iron, chromium, and nickel oxides, with an iron content of 65.8%, and can be used as a raw material for steel smelting.

[0085] Example 2

[0086] The serpentine mineral raw material selected for the test is Shandong Tai'an serpentine. The mineral types contained are mainly serpentine, with a small amount of talc, magnetite and quartz. The main chemical composition is shown in Table 2:

[0087] Table 2 Main chemical components of serpentine tailings

[0088] element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[TFe2O3]]> MgO CaO Loss on ignition other <![CDATA[Content w B / %]]> 37.89 0.81 6.91 40.25 0.54 13.03 0.47

[0089] S1. Processing Shandong Tai'an serpentine tailings into mineral powder with a particle size of less than 100 mesh, mixing potassium hydroxide and the mineral powder at a molar ratio of potassium hydroxide to silicon dioxide in the mineral powder of 4.0, placing the mixture in a closed high-temperature furnace with coke, and roasting it at a temperature of 800° C. for 120 minutes to obtain a roasting reaction product, wherein the roasting reaction product mainly contains potassium magnesium silicate, potassium silicate, magnesium oxide, hematite, and potassium chromate.

[0090] S2. The roasting reaction product was placed in a reactor containing potassium hydroxide and having a pH value of 7.5 and a stirring and heating device for leaching. The leaching reaction was performed at a liquid-to-solid ratio of 200 g / L, a temperature of 90° C., and a time of 90 minutes. After the leaching was completed, the leached product was filtered to obtain a filter residue I and a filtrate I. The filter residue I mainly contained periclase, maghemite, magnesium hydroxide, and chromium hydroxide. The filtrate I was refined water glass with a SiO2 concentration of 79.8 g / L and a SiO2 purity of 99.95%. The silica leaching rate was 95.0%, the chromium ion leaching rate was only 1.5%, and the iron ion leaching rate was 0.1%.

[0091] S3, the filter residue I was placed in a sulfuric acid solution with a pH value of 5.0 for leaching, the leaching solid-liquid ratio was 200g / L, the leaching temperature was 30°C, and the leaching time was 120min. After the leaching was completed, the filtrate II and the filter residue II were obtained by filtration and rinsing. Mg 2+ The leaching rate was 90.0%, the iron ion leaching rate was 1.5%; the Mg content in the filtrate was 2+ The mass concentration is 24.50 g / L. After evaporation and drying, magnesium sulfate powder is obtained, and the mass percentage of MgSO4 in the magnesium sulfate powder is 99.50%. The filter residue II mainly contains iron, chromium, and nickel oxides, with an iron content of 67.5%, which can be used as a raw material for steel smelting.

[0092] Example 3

[0093] The serpentine-containing mineral raw materials selected for the test are serpentine-type stripping waste rocks from the asbestos mine in Shimian County. The mineral types contained are mainly serpentine, with a small amount of talc, magnetite, and quartz. The main chemical compositions are shown in Table 3:

[0094] Table 3 Main chemical compositions of stripped waste rock

[0095] element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[TFe2O3]]> MgO CaO Loss on ignition other <![CDATA[Content w B / %]]> 40.33 1.20 3.09 41.59 0.47 12.74 0.48

[0096] S1. Processing serpentinite-type stripping waste rock from the asbestos mine in Shimian County into mineral powder with a particle size of less than 50 mesh, mixing potassium hydroxide and the mineral powder at a molar ratio of potassium hydroxide to silicon dioxide in the mineral powder of 3.5, placing the mixture in a closed high-temperature furnace with coal powder, and roasting the mixture at a temperature of 750° C. for 100 minutes to obtain a roasting reaction product, wherein the roasting reaction product mainly contains potassium magnesium silicate, potassium silicate, magnesium oxide, hematite, and potassium chromate.

[0097] S2. The roasting reaction product was placed in a reactor containing potassium hydroxide and having a pH value of 9 and a stirring and heating device for leaching. The leaching reaction was carried out at a liquid-to-solid ratio of 150 g / L, a temperature of 80° C., and a time of 60 minutes. After the leaching was completed, the leached product was filtered to obtain a filter residue I and a filtrate I. The filter residue I mainly contained periclase, magmasite, magnesium hydroxide, and chromium hydroxide. The filtrate I was refined water glass with a SiO2 concentration of 68.3 g / L and a SiO2 purity of 99.85%. The silica leaching rate was 90.0%, the chromium ion leaching rate was only 1.1%, and the iron ion leaching rate was 0.9%.

[0098] S3, the filter residue I was placed in a sulfuric acid solution with a pH value of 4.5 for leaching, the leaching solid-liquid ratio was 150g / L, the leaching temperature was 25°C, and the leaching time was 90min. After the leaching was completed, the filtrate II and the filter residue II were obtained by filtration and rinsing. Mg 2+ The leaching rate was 85.0%, the iron ion leaching rate was 1.1%; the Mg content in the filtrate was 2+ The mass concentration is 19.50 g / L. After evaporation and drying, magnesium sulfate powder is obtained, and the mass percentage of MgSO4 in the magnesium sulfate powder is 99.00%. The filter residue II mainly contains iron, chromium, and nickel oxides, with an iron content of 65.2%, which can be used as a raw material for steel smelting.

[0099] Example 4

[0100] The serpentine-containing mineral raw material selected for the test is the Da'an asbestos tailings in Shaanxi Province. The mineral types contained are mainly serpentine, with a small amount of brucite, magnetite, chlorite, brucite and quartz. The main chemical compositions are shown in Table 4:

[0101] Table 4 Main chemical components of asbestos tailings

[0102] element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[TFe2O3]]> MgO CaO Loss on ignition other <![CDATA[Content w B / %]]> 37.69 1.20 7.75 40.13 0.42 14.5 0.31

[0103] S1. Processing the Da'an asbestos tailings in Shaanxi Province into mineral powder with a particle size of less than 50 mesh, mixing sodium hydroxide and the mineral powder at a molar ratio of sodium hydroxide to silicon dioxide in the mineral powder of 3.5, placing the mixture in a sealed high-temperature furnace with carbon black, and roasting it at a temperature of 700° C. for 120 minutes to obtain a roasting reaction product, which mainly contains sodium magnesium silicate, sodium silicate, magnesium oxide, hematite, and sodium chromate.

[0104] S2. The roasting reaction product was placed in a reactor containing sodium hydroxide at a pH of 8.0 and equipped with a stirring and heating device for leaching. The leaching reaction was performed at a liquid-to-solid ratio of 150 g / L, a temperature of 85° C., and a time of 100 min. After the leaching was completed, the leached product was filtered to obtain a filter residue I and a filtrate I. The filter residue I mainly contained periclase, magmasite, magnesium hydroxide, and chromium hydroxide. The filtrate I was refined water glass with a SiO2 concentration of 65.3 g / L and a SiO2 purity of 99.85%. The silica leaching rate was 93.4%, the chromium ion leaching rate was only 0.9%, and the iron ion leaching rate was 0.8%.

[0105] S3, the filter residue I was placed in a hydrochloric acid solution with a pH value of 4.8 for leaching, the leaching solid-liquid ratio was 200g / L, the leaching temperature was 30°C, and the leaching time was 100min. After the leaching was completed, the filtrate II and the filter residue II were obtained by filtration and rinsing. Mg 2+ The leaching rate was 85.0%, the iron ion leaching rate was 1.2%; the Mg content in the filtrate was 2+ The mass concentration is 21.50 g / L. After evaporation and drying, magnesium chloride powder is obtained, in which the mass percentage of MgCl2 in the magnesium chloride powder is 98.90%. The filter residue II mainly contains iron, chromium, and nickel oxides, with an iron content of 65.5%, and can be used as a raw material for steel smelting.

[0106] Example 5

[0107] The Qinghai Mangya serpentinite selected for the test contains mainly serpentine, with a small amount of talc, magnetite and magnesite. The main chemical compositions are shown in Table 5:

[0108] Table 5 Main chemical components of serpentinite

[0109] element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[TFe2O3]]> MgO CaO Loss on ignition other <![CDATA[Content w B / %]]> 39.89 0.81 6.91 40.25 0.54 12.5 0.47

[0110] S1. Process the Qinghai Mangya serpentinite into a mineral powder with a particle size of less than 50 mesh. Mix sodium hydroxide and the mineral powder at a molar ratio of sodium hydroxide to silicon dioxide in the mineral powder of 3.8, place the mixture in a sealed high-temperature furnace with activated carbon, and roast it at a temperature of 730° C. for 120 minutes to obtain a roasting reaction product. The roasting reaction product mainly contains sodium magnesium silicate, sodium silicate, magnesium oxide, hematite, and sodium chromate.

[0111] S2. The roasting reaction product was placed in a reactor containing sodium hydroxide at a pH of 8.0 and equipped with a stirring and heating device for leaching. The leaching reaction was performed at a liquid-to-solid ratio of 120 g / L, a temperature of 90° C., and a time of 100 min. After the leaching was completed, the leached product was filtered to obtain a filter residue I and a filtrate I. The filter residue I mainly contained periclase, magmasite, magnesium hydroxide, and chromium hydroxide. The filtrate I was refined water glass with a SiO2 concentration of 75.3 g / L and a SiO2 purity of 99.90%. The silica leaching rate was 92.4%, the chromium ion leaching rate was only 1.0%, and the iron ion leaching rate was 1.8%.

[0112] S3, the filter residue I was placed in a sulfuric acid solution with a pH value of 4.8 for leaching, the leaching solid-liquid ratio was 180g / L, the leaching temperature was 25°C, and the leaching time was 100min. After the leaching was completed, the filtrate II and the filter residue II were obtained by filtration and rinsing. Mg 2+ The leaching rate was 89.0%, the iron ion leaching rate was 0.9%; the Mg content in the filtrate was 2+ The mass concentration is 23.50 g / L. After evaporation and drying, magnesium sulfate powder is obtained, and the mass percentage of MgSO4 in the magnesium sulfate powder is 98.80%. The filter residue II mainly contains iron, chromium, and nickel oxides, with an iron content of 67.5%, which can be used as a raw material for steel smelting.

[0113] Figure 2 The XRD patterns of the products of Cr2O3 alkali roasting under aerobic conditions and reducing conditions are shown. From the figure, it can be seen that the products of Cr2O3 alkali roasting under aerobic conditions are Na2Cr2O7 and Na2CrO4, and Cr exists in hexavalent form; the product of Cr2O3 alkali roasting under reducing conditions is NaCrO2, and Cr exists in trivalent form.

[0114] Figure 3 The XRD patterns of the alkali-roasted slag and water-leached slag obtained from experiments according to the present invention are shown. As can be seen, sodium magnesium silicate, sodium orthosilicate, and periclase are formed in the slag (NB-750°C-M4.0). Maghemite and sodium chromate, with their contents below 10%, are not detected in the XRD pattern. After water leaching (NS-750°C-M4.0), the sodium magnesium silicate and sodium orthosilicate dissolve, leaving only the diffraction peak of periclase.

[0115] Although the present invention has been described above with reference to the exemplary embodiments and the accompanying drawings, it will be apparent to those skilled in the art that various modifications may be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for preparing refined water glass and magnesium salt from serpentine-containing mineral raw materials, characterized in that: The method comprises: 1) processing a serpentine-containing mineral raw material into a serpentine-containing mineral powder, uniformly mixing the serpentine-containing mineral powder with a reaction aid, and then performing a reduction roasting treatment to obtain a roasting reaction product; 2) placing the roasting reaction product in a leaching solution I to carry out a leaching reaction I, and filtering and rinsing after completion to obtain a filtrate I and a filter residue I, wherein the filtrate I is refined water glass; 3) placing the filter residue I in the leaching solution II to carry out leaching reaction II, filtering and rinsing after the end to obtain filtrate II and filter residue II, and post-treating the filtrate II to obtain refined magnesium salt.

2. The method for preparing refined water glass and magnesium salt from serpentine-containing mineral raw materials according to claim 1, characterized in that: The chemical composition of the serpentine-containing mineral raw material includes, by mass percentage, 37.0% to 42.0% SiO2, 36.0% to 42.0% MgO, 0.8% to 1.2% Al2O3, 3.0% to 8.0% TFe2O3, 0.4% to 0.7% CaO, 0.4% to 0.7% Cr2O3, 0.1% to 0.3% NiO, and 0.0% to 0.5% other impurity oxides; the loss on ignition is 11.0% to 13.5%; the serpentine-containing mineral raw material includes stripping waste rock and mineral processing tailings generated during the mining and mineral processing of serpentine and serpentine mines and chrysotile asbestos mines, the main mineral type is serpentine, and also includes one or more of talc, magnesite, magnetite, brucite, chlorite and quartz.

3. The method for preparing refined water glass and magnesium salt from serpentine-containing mineral raw materials according to claim 1, characterized in that: The reaction aid includes one or both of sodium hydroxide and potassium hydroxide; the mixing ratio is such that the molar ratio of the reaction aid to SiO2 in the serpentine-containing mineral powder is 3.0-4.

0.

4. The method for preparing refined water glass and magnesium salt from serpentine-containing mineral raw materials according to claim 1, characterized in that: The reduction roasting treatment is carried out in a closed high-temperature roasting furnace; the conditions for the reduction roasting treatment are adding a carbonaceous reducing agent and / or continuously introducing carbon monoxide into the closed roasting furnace; the temperature of the reduction roasting treatment is 700°C to 800°C, and the time of the reduction roasting treatment is 60min to 120min.

5. The method for preparing refined water glass and magnesium salt from serpentine-containing mineral raw materials according to claim 1, characterized in that: The leaching solution I is one of industrial pure water or an aqueous solution containing sodium hydroxide / potassium hydroxide with a pH value of 7.5 to 9. The equipment for the leaching reaction I includes a reactor with a stirring and heating device. The solid-liquid ratio of the roasting reaction product to the leaching solution I in the leaching reaction I is 100 to 200 g / L. The temperature of the leaching reaction I is 70° C. to 90° C., and the time is 30 min to 90 min. In the leaching reaction I, the leaching rate of SiO2 is 85.0% to 95.0%, the leaching rate of chromium ions is 0.5% to 1.5%, and the leaching rate of iron ions is 0.1% to 2.0%.

6. The method for preparing refined water glass and magnesium salt from serpentine-containing mineral raw materials according to claim 1, characterized in that: The leaching solution II is a solution of sulfuric acid and hydrochloric acid, and the pH value is maintained at 4.0-5.0 during the leaching process; the equipment for the leaching reaction II includes a reactor with a stirring and heating device; the solid-liquid ratio of the leaching solution II to the filter residue I is 100-200 g / L; the temperature of the leaching reaction II is 15° C.-30° C., and the time is 60 min-120 min; The Mg in the leaching reaction II 2+ The leaching rate is 78.0% to 90.0%, and the iron ion leaching rate is 0.8% to 1.5%; the filter residue II can be used as a raw material for steel smelting.

7. A refined water glass, characterized in that: The SiO2 mass concentration in the water glass is 31.5 g / L to 79.8 g / L, and the SiO2 purity is 99.80% to 99.95%; The refined water glass is prepared by the following method: 1) processing a serpentine-containing mineral raw material into a serpentine-containing mineral powder, uniformly mixing the raw material with a reaction aid, and then performing a reduction roasting treatment to obtain a roasting reaction product; 2) placing the roasting reaction product in a leaching solution I to carry out a leaching reaction I, filtering and rinsing after the reaction to obtain a filtrate I and a filter residue I, wherein the filtrate I is refined water glass.

8. The use of the purified water glass according to claim 7, characterized in that: The applications include: application in preparing high-purity silicon-containing compound series products, or application in preparing solid water glass.

9. A refined magnesium salt, characterized in that The refined magnesium salt is prepared by the method according to any one of claims 1 to 6; Mg in the refined magnesium salt 2+ The mass concentration is 11.34g / L~24.50g / L.

10. The use of the refined magnesium salt according to claim 9, characterized in that The application includes: application in preparing high-purity magnesium-containing compound series products, or application in preparing magnesium salt powder, wherein the mass percentage of MgSO4 and MgCl2 in the prepared magnesium salt powder is 98.80% to 99.50%.

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