Silicate mineral and production method thereof

Abstract

To provide silicate mineral having an average particle diameter larger than several hundred nm without containing impurities such as crystalline silica.SOLUTION: The silicate mineral powder of the present invention has a crystalline silica content of 0.05 wt.% or less and an asbestos content of 0.1 wt.% or less. The mineral preferably contains carbonate and preferably has an average particle diameter of 100 nm or more. Further, the silicate mineral powder of the present invention is obtained by subjecting natural silicate mineral to warm water treatment, hot water treatment, or hydrothermal reaction treatment at a pH of 4 or more and 9.4 or less. At this time, the temperature in the warm water treatment, hot water treatment, or hydrothermal reaction treatment is 120°C or more and 370°C or less, the pressure is equal to or higher than the saturation vapor pressure of water, and the processing time is 1 minute or more and 10 hours or less.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to silicate minerals and a method for producing the same.

Background Art

[0002] Silicate compounds are diverse among minerals and are widely used in cosmetics, foods, pharmaceuticals, and industrial products. Deep underground, groundwater is heated by volcanic activity to become high-temperature and high-pressure hot water (subcritical / supercritical water), which dissolves rocks to form a supercritical aqueous solution state. When it is depressurized and cooled near the ground, the solubility decreases and precipitation occurs. This is the principle of the formation of ore veins. As can be seen from the earth and sand components on the ground, silicate compounds are the main constituent components among them. Silicate compounds include not only silica SiO2, but also calcium silicate, magnesium silicate, iron silicate, sodium silicate, etc. containing many metals such as Al, Ca, Fe, K, Na, Mg, etc., or minerals containing multiple metals, and many of their hydrates are also formed.

Table 1

[0003] Naturally, due to the precipitation principle, impurities are often contained. Among them, it is often the case that SiO2, which is a constituent component, is contained as an impurity.

[0004] The object of the present invention is to remove these impurities generated in the precipitation process of silicate minerals, and it targets aluminum silicate, calcium silicate, magnesium silicate, iron silicate, etc. and their hydrates. Hereinafter, magnesium silicate hydrate (also referred to as talc, talcum, etc.) will be used as an example to explain this technology, but it is a technology that can be applied to other silicate minerals in principle.

[0005] Magnesium silicate hydrate is widely used in cosmetics, foods, pharmaceuticals, and industrial products. However, since it is a natural mineral, it often contains impurities. In commercial use, toxic substances and heavy metals are separated and removed before utilization. Nevertheless, in many cases, these materials, including talc which is a natural mineral, are likely to be contaminated with components that are likely to co-precipitate during mineral formation, such as SiO2, and these co-precipitating components often get mixed into the products. For example, it often contains a small amount of tremolite and chrysotile caused by asbestos. The inclusion of asbestos is not permitted not only in cosmetics, foods, pharmaceuticals, etc., but also in industrial products. The inclusion of other crystalline SiO2 (also referred to as crystalline silica, quartz, etc.) has also recently become a concern.

[0006] However, the formation of minerals underground is precipitation due to temperature and pressure, and the composition of the precipitate varies depending on the location where the minerals are mined. Scrutinizing and selecting parts that contain almost no such impurities for use has been regarded as the only solution, but still, there are many cases where trace amounts of impurities are contained, especially in application fields such as medical, food, and cosmetics, which has become a major problem.

[0007] Also, focusing on crystalline SiO2, since the physical properties required for existing component separation, such as the specific gravity of magnesium silicate hydrate and SiO2, are almost the same, separation by centrifugation, sedimentation separation, specific gravity separation, and also adsorption operations such as chromatography methods has been considered impossible.

[0008] Here, it has been proposed to artificially synthesize talc in the form of fine particles using hydrothermal synthesis including a supercritical field (see Patent Document 1).

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] However, the synthetic talc obtained by the method described in Patent Document 1 has a small particle size of 20 nm to 100 nm. In the application fields where hydrous silicate compounds such as talc are actually used, natural minerals are sieved by grinding and used. Therefore, the particle size is several tens of μm or more, and even when it is small, it is sub-μm or more. From the viewpoint of user safety (nano risk), it is desirable to provide talc with a larger particle size. In principle, it is possible to grow the particle size by a hydrothermal method or the like. However, in artificial synthesis, there are problems in terms of manufacturing cost, productivity, and optimization of properties. Actually, it is not a method for industrially producing particles of several hundreds of nm or more.

[0011] Therefore, even when trying to remove impurities from natural minerals, regarding crystalline silica, in the sense of dissolving and removing SiO2 impurities from the mixed system of magnesium hydrous silicate and impurity SiO2, impurities can be dissolved under alkaline conditions, but at the same time, magnesium hydrous silicate also dissolves. Therefore, there has been no study on separation and removal that leaves magnesium hydrous silicate while dissolving and removing SiO2 impurities. In principle, as an industrial method, conditions are required to dissolve only SiO2 without dissolving magnesium hydrous silicate. However, considering that mineral formation occurs simultaneously in nature in the first place, it is because their solubilities are almost the same that they are mixed, and the search for such conditions is extremely difficult.

[0012] Regarding asbestos, asbestos is serpentine and amphibole. Generally, it has heat resistance and is stable in both acids and alkalis. That is, under the conditions where it can be dissolved and removed, other components, for example, magnesium hydrous silicate itself will be dissolved, which is generally very difficult.

[0013] The present invention has been made in view of such problems, and it is to be able to provide a silicate mineral having an average particle size larger than several hundreds of nm without containing impurities such as crystalline silica.

Means for Solving the Problems

[0014] As a result of intensive research, the inventors of the present invention have found that by subjecting a silicate mineral derived from a natural mineral to hot water or hydrothermal reaction treatment at pH 9.4 or lower, toxic impurities such as crystalline silica and asbestos can be dissolved in water or removed by reaction modification, and thus the present invention has been completed. Specifically, the present invention provides the following.

[0015] The present invention is a method for producing a silicate mineral powder, including a step of subjecting a silicate mineral derived from a natural mineral to hot water or hydrothermal reaction treatment at pH 9.4 or lower. Further, carbonic acid or the like can coexist in the reaction field, thereby controlling the pH to be low and enabling reaction modification and removal of impurities.

[0016] Hydrothermal reaction is widely used as a single crystal growth method for metal oxide crystals, including quartz. Under hydrothermal conditions, metal oxides repeatedly dissolve and precipitate to grow crystals. This crystal growth is called Ostwald ripening. Unstable fine particles and sharp tips with high surface energy are more likely to dissolve, and single crystal growth proceeds so that more stable surfaces are exposed. In practice, it is industrially used as a method for promoting faster crystal growth and producing large single crystals by utilizing the mechanism and principle of this Ostwald ripening.

[0017] Since the solubility of metal oxides varies with temperature, generally, in order to promote this single crystal growth, a temperature distribution is created in the crystal growth vessel to perform crystal growth at a higher speed. Under subcritical hydrothermal conditions or high-pressure supercritical conditions (high water density), a method is adopted in which raw materials are dissolved in a high-temperature field and seed crystals are grown in a low-temperature field. When using a relatively low-pressure and low-density supercritical water state, conversely, precipitation is caused in a high-temperature (low water density) field, and natural stagnation that easily occurs is actively utilized. Usually, it takes at least several hours, generally several days to several weeks.

[0018] Considering the principle of Ostwald ripening, when magnesium silicate hydrate such as talc with different particle sizes and shapes is hydrothermally aged, dissolution occurs in both components from fine particles and acicular particles. Different from crystal growth, the present invention is not about the growth of tremolite, chrysotile, or crystalline silica (quartz) that may be contained as impurities, but about the dissolution or reaction modification and removal of impurities. By suppressing the dissolution of silicate minerals and causing the dissolution or reaction modification of impurities such as crystalline silica more selectively, the main component silicate minerals free of impurities including crystalline silica are adjusted.

[0019] In addition, compared with the artificial synthesis of talc using hydrothermal synthesis, in which the adjustment of silicate minerals free of crystalline silica and chrysotile as impurities is also possible in principle, it is excellent in terms of manufacturing cost. Also, since the raw material is a pulverized natural mineral, it is possible to recover particles with a particle size of 100 nm or more required in the market.

[0020] Since it is a reaction field where Ostwald ripening occurs, the shape of the recovered silicate mineral particles has fewer fine particulate products and a rounder particle shape compared to general pulverized natural products. Also, there are more hydroxyl groups on the surface of the product.

[0021] The pH is 9.4 or less. At high pH, crystalline silica can be dissolved, but at the same time, the dissolution of silicate minerals also occurs. In the first place, subcritical and supercritical hydrothermal synthesis (artificial synthesis) of silicate minerals preferably uses a low pH. Since silicate minerals precipitate under this condition, it is considered to be desirable in principle as a condition for dissolving only crystalline silica without dissolving silicate minerals.

[0022] This concept is the same for the removal of impurities in asbestos such as chrysotile. Since asbestos such as chrysotile is a mineral showing basicity, it is possible in principle to set conditions for dissolving these and precipitating silicate minerals by not setting a high pH under hydrothermal conditions.

[0023] These impurities are particularly problematic when they are in the form of acicular products. However, under hydrothermal conditions, the acicular substances dissolve from their tips. Considering the dissolution rate and amount of a large amount of silicate minerals, even if the same amount dissolves, ultimately, only the silicate minerals present in large quantities can be left.

[0024] An acid can coexist to lower the pH, and carbonic acid can also be used as the acid. In this case, carbonate formation may occur depending on the conditions. As the talc formation mechanism in the reaction field of mineral formation deep underground, the following reaction is known.

Number

[0025] This shows that serpentine (chrysotile) reacts with CO2 under hydrothermal conditions to form talc. The Mg in chrysotile precipitates as magnesium carbonate. However, since the solubility of magnesium carbonate under hydrothermal conditions is higher than that of other products, it can also be dissolved and removed by a semi-batch extraction operation.

[0026] Also, recent research has reported carbonation by the reaction of calcium silicate, etc. with CO2. Not only the study of mineral formation mechanisms, but also the hardening of calcium silicate compounds by carbonation (Goto et al., Inorganic Materials, Vol. 5, Jan. 22 - 27 (1998)), the CO2 absorption into concrete (CO2-SUICOM (registered trademark) process), and the synthesis of artificial marble by the CO2 coexistence hydrothermal reaction with calcium silicate by Professor Richard Riman of Rutgers University in the United States, etc. are being put into practical use as research and development and technology development for solving the CO2 problem. That is, carbonation proceeds under hydrothermal conditions in the coexistence of CO2.

[0027] On the other hand, in the geophysical field, the following is known as another formation mechanism of talc formation underground.

Number

[0028] This reaction mechanism is a reaction in which talc is formed in the presence of silica under hydrothermal conditions. As described above, it is suggested that it is possible to modify talc through the reaction between carbonate and silica.

[0029] That is, tremolite mixed as a trace component Ca2(Mg,Fe)5Si8O 22 (OH)2 (where Mg / (Mg + Fe) = 1.0 - 0.9) However, when a small amount of tremolite is mixed, under hydrothermal conditions, not only dissolution and removal occur, but in the presence of CO2, it carbonates, and at the same time, the silica component present as an impurity also reacts while dissolving, resulting in denaturation into talc.

[0030] In addition, in the present invention, the hot water or hot water treatment or hydrothermal reaction treatment is preferably carried out in the presence of Mg ions. When crystalline silica or the like is contained in the mineral, from an equilibrium perspective, coexistence of Mg may promote the formation of magnesium silicate. Simply put, there is also a reaction in which SiO2 combines with Mg. However, in reality, Mg ions and Si ions coexist due to the dissolution of silica and magnesium silicate. By supplying magnesium ions, the dissolution equilibrium of silica and magnesium silicate can be made to predominantly cause the dissolution of silica.

[0031] The silicate mineral derived from natural minerals as raw materials is provided by pulverizing natural minerals. Therefore, it is difficult to make the average particle size less than 200 nm, and for the product after hydrothermal reaction treatment, the average particle size is 200 nm or more.

[0032] Therefore, according to the present invention, talc having an average particle size larger than 100 nm can be provided without containing impurities such as crystalline silica and asbestos components.

[0033] In the present invention, it is preferable that the temperature in the warm water or hot water treatment or the hydrothermal reaction treatment is 70° C. or higher and 370° C. or lower, and the pressure is equal to or higher than the saturated vapor pressure of water.

[0034] According to the present invention, impurities such as crystalline silica or asbestos can be dissolved and reacted to remove them by using low-temperature heat of 370°C or less (preferably 300°C or less, more preferably 250°C or less, even more preferably 200°C or less, and particularly preferably 150°C or less), which is more advantageous in terms of production costs. As low-temperature heat, not only heat from a heat source device but also reuse of waste heat within a factory can be considered.

[0035] The present invention can be applied to any of a batch apparatus, a semi-batch apparatus, and a flow-through apparatus. However, it is preferable to carry out the warm water or hot water treatment or the hydrothermal reaction treatment using a semi-batch apparatus or a flow-through apparatus, and it is more preferable to carry out the warm water or hot water treatment or the hydrothermal reaction treatment using a semi-batch apparatus.

[0036] The solubility of silica in pure water has been reported. However, in the case of hydrothermal treatment of minerals containing other ions, as in this system, the dissolution of those minerals naturally occurs, and the solubility differs from that of silica in high-temperature, high-pressure water. In general, the solubility of a specific component in the presence of other minerals and the concentration of dissolved chemical species can be solved by simultaneously solving the solubility equilibrium equation of any substance, and further, the dissociation equilibrium of water and the charge balance. The necessary chemical equilibrium can be predicted with good accuracy, including in the supercritical region, using the HKF (Helgeson Kirkham Flouer) model and the improved HKF model by Sue et al. (Sue, K., Hakuta, Y., Smith, RL, Adschiri, T., & Arai, K. (1999). Solubility of lead(II) oxide and copper(II) oxide in subcritical and supercritical water. Journal of Chemical & Engineering Data, 44(6), 1422-1426. https: / / doi.org / 10.1021 / je9901029)

[0037] For example, by adding an alkali or due to the influence of coexisting ions, the saturation solubility becomes larger. Also, in the process of mineral precipitation underground, when minerals precipitate and when silica precipitates as an impurity, it is suggested that the solubility of the precipitated minerals is low and the precipitation rate is high. It is inferred that not only the above equilibrium theory but also kinetically, the situation is such that silica is easily dissolved. Although this has been verified experimentally, it can be fully explained that dissolution 10 times or more faster can be achieved not only in terms of equilibrium theory but also kinetically.

[0038] As a reaction system, the optimum value of the water flow rate during operation is determined from this equilibrium theory and kinetic theory.

[0039] By using a semi-batch apparatus, heat recovery and preheating can also be carried out in warm water / hot water treatment or hydrothermal reaction treatment, so it is even more excellent in terms of manufacturing cost. Also, since impurities such as crystalline silica and asbestos that have been extracted and removed can be removed outside the system, contamination due to their reprecipitation can be prevented.

[0040] When the reaction apparatus is a semi-batch apparatus, the amount of the aqueous solvent supplied to the semi-batch apparatus is preferably 0.1 times or more of the theoretical amount that saturates and dissolves the crystalline silica contained in the silicate mineral as a raw material in the reaction solution containing coexisting ions in the reaction field. Alternatively, the amount of crystalline silica contained in the silicate mineral as a raw material charged into the semi-batch apparatus is preferably 10 times or less of the theoretical amount that saturates and dissolves in the reaction solution containing coexisting ions in the reaction field.

[0041] When using a flow-through device, a silicate mineral is supplied in a suspended state in water, and hot water or hot water treatment or hydrothermal reaction treatment is performed. Heat recovery at the outlet and further utilization as preheating of the raw material can be carried out. Unlike the semi-batch device, the temperature of the extraction tank rises. Since there is no heat loss during cooling, the heat recovery rate is improved. At this time, silica dissolved in the cooling section may re-precipitate in the subsequent cooling section. To avoid this, it is necessary to suppress the Ostwald ripening and recrystallization growth of the remaining silica by sufficiently dissolving crystalline silica and rapidly cooling. The condition study can be carried out by a small batch test.

[0042] In addition, the concentration of the silicate mineral water slurry supplied to the flow-through device is preferably 0.1 times or more of the theoretical amount that saturates and dissolves the crystalline silica contained in the silicate mineral as a raw material in a reaction solution containing coexisting ions in the reaction field.

Effects of the Invention

[0043] According to the present invention, a silicate mineral having an average particle diameter larger than several hundred nanometers can be provided without containing impurities such as crystalline silica.

Brief Description of the Drawings

[0044]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0045] Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention.

[0046] <Manufacturing Apparatus for Hydrous Magnesium Silicate Powder> Figure 1 is a schematic diagram of a production apparatus 1 for magnesium silicate hydrate powder.

[0047] The production apparatus 1 includes an extraction means 10 and, if necessary, a cooling means 20.

[0048] 〔Extraction means 10〕 The extraction means 10 is an apparatus that brings a raw material liquid into contact with an aqueous material and subjects the raw material to warm water or hot water treatment or hydrothermal reaction treatment. The form of the extraction means 10 may be any of a batch apparatus, a semi-batch apparatus, and a continuous apparatus. However, since the temperature in hydrothermal reaction treatment or the like can be made lower, and not only the heat from the heat source apparatus but also the waste heat in the factory can be utilized, in terms of manufacturing cost advantages, the extraction means 10 is preferably a batch apparatus or a semi-batch apparatus, and it is more preferable to perform warm water or hot water treatment or hydrothermal reaction treatment using a semi-batch apparatus.

[0049] By using a semi-batch apparatus, heat recovery and preheating in warm water / hot water treatment or hydrothermal reaction treatment can also be performed, so it is even more excellent in terms of manufacturing cost. In addition, since impurities such as crystalline silica and asbestos removed by extraction can be removed outside the system, contamination due to their reprecipitation can be prevented.

[0050] Also, the form of the extraction means 10 may be a continuous apparatus (flow-through apparatus). When using a flow-through apparatus, a silicate mineral is supplied in a suspended state in water, and warm water or hot water treatment or hydrothermal reaction treatment is performed. Heat recovery at the outlet and further utilization as preheating of the raw material can be carried out. Unlike the semi-batch apparatus, there is no heat loss during the temperature rise and cooling of the extraction tank, so the heat recovery rate is improved. At this time, there is a possibility that silica or the like dissolved in the cooling section will reprecipitate in the subsequent cooling section. To avoid this, it is necessary to suppress the Ostwald ripening and recrystallization growth of the remaining silica by sufficient dissolution of crystalline silica and rapid cooling. The condition study can be carried out by a small-scale batch test.

[0051] Hereinafter, unless otherwise specified, the extraction means 10 will be described as a semi-rotary device, but it is not limited to this.

[0052] [Raw material] The raw material charged into the extraction means 10 is a silicate mineral, which may be derived from natural minerals or synthetic minerals, but preferably a silicate mineral derived from natural minerals.

[0053] The types of metals constituting the silicate mineral are not particularly limited, and in addition to alkali metals and alkaline earth metals, aluminum, iron, etc. can be mentioned. Specific examples of silicate minerals include aluminum silicate, magnesium silicate, calcium silicate, iron silicate, or silicate minerals containing a plurality of these metals. Further, the silicate mineral may be a hydrous silicate mineral as its hydrate.

[0054] For example, when the silicate mineral is a natural mineral such as talc (hydrous magnesium silicate), according to the Enforcement Order of the Industrial Safety and Health Act (Cabinet Order No. 318 of 1972) and the Asbestos Hazard Prevention Regulations (Ministry of Health, Labour and Welfare Ordinance No. 21 of 2005), the content of asbestos (tremolite, chrysotile, etc.) contained in the natural mineral is set to 0.1% or less. Therefore, it is preferable to use a silicate mineral with a content rate of 0.1% or less as the raw material.

[0055] By the way, as a method for determining the content rate of asbestos in talc using the X-ray diffraction method, "Analysis Method of Asbestos Content in Natural Minerals", which is an annex to Kiankaifa No. 0828001, is adopted. In this method, it is assumed that a general-purpose X-ray diffraction device (XRD device) is used, and the measurement conditions are as follows ("Analysis Method of Asbestos Content in Talc", Asbestos Analysis Manual for Preliminary Investigation Based on the Asbestos Regulations, March 2018, Ministry of Health, Labour and Welfare). Tube voltage: 40 kV or more Tube current: 30 mA or more Anticathode: Cu Monochromatization: Graphite monochromator or Ni filter Detector: Scintillation counter, proportional counter, Geiger counter, semiconductor detector, etc. Slit system: Light-receiving slit 0.3 mm or 0.2 mm Diverging slit: 1° Scattering slit: 1° Goniometer scanning speed: 1 / 8° per minute or less Time constant: Use an appropriate time constant. Full scale of the chart: For the measurement of the intensity of the diffraction line, the net peak area obtained by subtracting the background is determined. Select an appropriate full scale on the recording chart so that the diffraction line can be confirmed as a peak.

[0056] Generally, in the measurement of trace components, the measurement peak may be hidden in the baseline noise. Therefore, in order to increase the signal / noise ratio, it is necessary to set the integration time to a long time. As a result, trace detection is possible in principle without using a powerful radiation source.

[0057] However, if evaluated within the measurement time used for general crystal structure analysis, the integration time may be insufficient to fully detect the peak, and the asbestos content may be determined to be 0.1% by weight or less, which is the safety standard.

[0058] In the invention described in this embodiment, long-time measurement is carried out with full consideration of that point, and analysis is performed based on the calibration curve created based on precise baseline evaluation. By subjecting asbestos to reaction modification and removal, the asbestos content is truly made 0.1% by weight or less, that is, while relying on the determination result of a general-purpose X-ray diffractometer as specified in the attached table of Kianhua Fa No. 0828001, by making full use of precise analysis methods, it is confirmed that the safety standard in the attached table is achieved with sufficient accuracy.

[0059] [Dispersion medium] In addition, the dispersion medium for dispersing the raw materials is an aqueous material. The aqueous material refers to water, a polar organic solvent, or a mixed solvent of water and a polar organic solvent. Examples of the aqueous material include water, alcohols, carboxylic acids, ketones, ethers, esters, amides, amines, sulfur compounds, etc., and mixtures thereof.

[0060] Examples of the alcohols include methanol, ethanol, isopropyl alcohol, t-butyl alcohol, propylene glycol, and phenol.

[0061] Examples of the carboxylic acids include lower carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, and caproic acid.

[0062] Examples of the ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone.

[0063] Examples of the ethers include ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, tetrahydrofuran, dioxane, and methyl cellosolve.

[0064] Examples of the esters include ethyl acetate and butyl acetate.

[0065] Examples of the amides include formamide, dimethylformamide, acetamide, dimethylacetamide, nitromethane, and acetonitrile.

[0066] Examples of the amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, and hexamethylenediamine.

[0067] Examples of the sulfur compounds include dimethyl sulfoxide.

[0068] Among them, since the handling is easy, the aqueous material preferably contains one or more selected from water, alcohols, and carboxylic acids, and more preferably is water.

[0069] Also, for reaction field control, a pH adjuster, an oxidizing agent, or a reducing agent can be added to the aqueous material.

[0070] Examples of the pH adjuster include hydrochloric acid, nitric acid, acetic acid, sulfuric acid, carbonic acid, or their ammonium salts as acids, and potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, or ammonia as alkalis.

[0071] Examples of the oxidizing agent / reducing agent include hydrogen peroxide, oxygen, nitric acid, formic acid, hydrazine, hydrogen, ammonia, ethanol, formaldehyde, etc.

[0072] These substances not only simply relate to the solubility of the target impurities but also function as reactive substances.

[0073] For example, when carbonic acid or CO2 coexists in the aqueous material, carbonate formation occurs, and further, through the reaction with silica, transformation from toxic impurity minerals to non-toxic carbonate minerals or talc may occur.

[0074] Also, it is preferable that Mg ions are added to the aqueous material. As a result, the subsequent warm water or hot water treatment or hydrothermal reaction treatment will be carried out in the presence of Mg ions.

[0075] When crystalline silica or the like is contained in a mineral, the formation of magnesium silicate may be promoted by coexisting Mg in an equilibrium theory. Simply put, there is also a reaction in which SiO2 combines with Mg. However, in reality, Mg ions and Si ions coexist due to the dissolution of silica and magnesium silicate. However, if magnesium ions are supplied, the dissolution equilibrium of the silica and magnesium silicate can also be made to predominantly cause the dissolution of silica. Therefore, it is preferable that Mg ions are added to the aqueous material.

[0076] [Raw material liquid] In the present embodiment, a raw material liquid in which a raw material is dispersed using a dispersion medium is charged into the extraction means 10. The form of the raw material liquid can be charged as a powder or as a fluid fluid. If it has fluidity, it is not particularly limited, and examples include an aqueous solution, slurry, paste, or suspension containing the raw material components.

[0077] When it is difficult to prepare an aqueous slurry, the raw material may be dispersed in an aqueous material such as ethanol to form a slurry.

[0078] When the reaction apparatus is a semi-batch apparatus, the amount of the aqueous solvent supplied to the semi-batch apparatus is preferably 0.1 times or more, more preferably 0.3 times or more, still more preferably 0.5 times or more, and even more preferably 0.8 times or more of the theoretical amount for saturating and dissolving the crystalline silica contained in the silicate mineral as the raw material in the reaction solution containing the coexisting ions in the reaction field. Alternatively, the amount of the crystalline silica contained in the silicate mineral as the raw material charged into the semi-batch apparatus is preferably 10 times or less, more preferably 3.5 times or less, still more preferably 2 times or less, and even more preferably 1.3 times or less of the theoretical amount for saturating and dissolving in the reaction solution containing the coexisting ions in the reaction field.

[0079] In this specification, it is preferable that the amount of crystalline silica is 0.1 times or more the theoretical amount at which it is saturated and dissolved in a reaction solution containing coexisting ions in the reaction field. Stated simply in terms of chemical equilibrium theory, the preferable amount of crystalline silica is equal to or more than the theoretical amount of water at which it is saturated and dissolved, and the degree of freedom is narrow. However, in the present invention, reaction rate theory dominates over chemical equilibrium theory, and the property that silica is more soluble than talc is utilized. For example, when an alkali is added or when Mg ions are added, the chemical equilibrium changes. Also, since the dissolution rate of crystalline silica simultaneously becomes higher than that of other minerals such as talc, in the case of a semi-batch process, a process in a flow-through apparatus, or a batch process for a short time, it becomes kinetically advantageous, and thus the amount of crystalline silica can be even less than the theoretical amount of water at which it is saturated and dissolved. Therefore, regarding the amount of crystalline silica, the degree of freedom is high, and it is sufficient if it is 0.1 times or more the theoretical amount.

[0080] The same applies when the extraction means 10 is a flow-through apparatus. The concentration of the silicate mineral water slurry supplied to the flow-through apparatus is preferably 0.1 times or more the theoretical amount at which the crystalline silica contained in the silicate mineral as a raw material is saturated and dissolved in a reaction solution containing coexisting ions in the reaction field, more preferably 0.3 times or more, still more preferably 0.5 times or more, and even more preferably 0.8 times or more.

[0081] In the present invention, the theoretical amount at which it is saturated and dissolved in a reaction solution containing coexisting ions in the reaction field can be determined using the HKF (Helgeson Kirkham Flouer) model. The solubility evaluation method is as described above.

[0082] The pH of the raw material liquid charged into the extraction means is 9.4 or less. If the pH exceeds 9.4, even when hydrothermal reaction treatment or the like is performed using hydrous magnesium silicate derived from natural minerals as a raw material, there is a possibility that the crystalline silica that can be contained in the raw material cannot be sufficiently dissolved, which is not preferable.

[0083] In order to dissolve impurities more preferably in the solvent, the upper limit of the pH is preferably 7 or less. Further, from the viewpoint of causing transformation from impurity minerals to talc formation by coexisting carbonic acid or CO2 in the aqueous material, the pH is more preferably 6 or less, and even more preferably 5 or less.

[0084] The lower limit of the pH is not particularly limited, but from the viewpoint of suppressing corrosion of the apparatus including the extraction means 10, the lower limit of the pH is preferably 1 or more, and more preferably 2 or more. In addition, from the viewpoint of causing transformation from impurity minerals to talc formation by coexisting carbonic acid or CO2 in the aqueous material, the pH is more preferably 3 or more, and even more preferably 4 or more.

[0085] The timing of being in the coexistence of an acid or a base is not particularly limited, and it is sufficient if it is in the coexistence of an acid or a base before the raw material liquid and the aqueous material come into contact with each other by the extraction means 10. However, in order to simplify the configuration of the manufacturing apparatus 1, it is preferable to supply an acid or a base in the raw material adjustment stage to make the raw material liquid acidic or basic.

[0086] Although not essential, the raw material liquid is preferably deaerated. Examples of the raw material deaeration apparatus include existing technology deaeration apparatuses such as a deaeration apparatus using ultrasonic waves, a deaeration apparatus performing reduced pressure, a deaeration apparatus feeding a rare gas into the raw material liquid, a deaeration apparatus using a permeation membrane, and a deaeration apparatus combining these existing technology deaeration apparatuses. By deaerating the raw material liquid, corrosion of the extraction means 10 and the cooling means 20 due to dissolved oxygen can be suppressed.

[0087] [Supply of aqueous material] Subsequently, the aqueous material continuously supplied to the extraction means 10 will be described.

[0088] Examples of the type of the aqueous material include the materials described above as the dispersion medium.

[0089] Although not necessary, the aqueous material is preferably degassed. As the degassing device for the aqueous material, the device described above as the degassing device for the raw material can be mentioned. By degassing the aqueous material, fluctuations in the supply amount of the aqueous material caused by bubbles or the like generated by the dissolved gas can be suppressed. In addition, corrosion of the extraction means 10 and the cooling means 20 due to dissolved oxygen can be suppressed. In addition, dissolved oxygen affects the redox state of the hydrothermal reaction field, and the presence of gases such as CO2 that strongly affect the reforming reaction under hydrothermal conditions is also an important factor for controllable processing.

[0090] The aqueous material is in a pressurized state by a pressure pump or the like. By pressurizing and further heating the aqueous material, the aqueous material can be brought into a subcritical state, and the aqueous material can be continuously supplied to the extraction means 10.

[0091] The pressurized aqueous material is preferably hot water or a subcritical aqueous material. When the aqueous material is water, subcritical water has a high solubility in silica. Therefore, it is preferable that the water is in a liquid state (liquid phase) after pressurization, or that the liquid phase is included as the main phase. However, even water in a state called gaseous water or water vapor (or steam) can form a condensed phase between particles by capillary force and exhibit the same behavior as liquid water, so these states of water are also included. Also, when the aqueous material is in a supercritical state, a high density is required to exhibit a high solubility, and the pressure for that purpose needs to be a pressure higher than the critical pressure, which is not desirable for industrial mass production. Also, the amount of hydroxy groups generated on the raw material surface is less than in the case of a pre-critical state, which can affect the dissolution of crystalline silica, asbestos, etc. that may be contained in the raw material.

[0092] The "warm water condition, hot water condition, or hydrothermal condition" according to the present invention is defined as a coexistence condition of liquid water having a reaction temperature of 70°C or higher and 370°C or lower. However, when fine particles are the target, due to the reaction and dissolution action in the condensed state by the capillary force between the fine particles, in such a special case, the supply system may be a condition in which water in a state called gaseous water vapor (or steam) coexists.

[0093] The pressure of the aqueous material after pressurization is equal to or higher than the saturated vapor pressure. If it is lower than the saturated vapor pressure, even when the raw material liquid is brought into contact with the pressurized aqueous material, impurities such as crystalline silica and asbestos that may be contained in the raw material may not be completely dissolved or removed by reaction modification, which is not preferable.

[0094] However, as a special example, even if the particle size is small and capillary force acts between particles, and the water is in a state below the saturated vapor pressure, that is, water called water vapor (or steam), a similar dissolution effect may be exhibited.

[0095] Since the removal of impurities such as crystalline silica and asbestos that may be contained in the raw material can be more preferably advanced, it is desirable that the pressure of the aqueous material after pressurization is equal to or higher than the saturated vapor pressure at the treatment temperature. For example, when the treatment temperature is 120°C, it is 0.2 MPa or higher, and when it is 170°C, it is 0.8 MPa or higher. It is lower at lower temperatures and higher at higher temperatures. At the critical point of 374°C, it is 22.1 MPa or higher. The pressure of the aqueous material after pressurization is preferably 0.2 MPa or higher, more preferably 0.5 MPa or higher, and even more preferably 1 MPa or higher. Even at a lower temperature, for example, 70°C, the solubility decreases, so the treatment efficiency and treatment speed decrease, but a similar removal effect is expected in principle. In that case, since it is 0.03 MPa and below atmospheric pressure, the operation can be carried out at normal pressure and hot water treatment can be performed.

[0096] Also, the pressure of the aqueous material after pressurization is 40 MPa or lower in the supercritical region, more preferably 20 MPa or lower, and even more preferably 10 MPa or lower. However, basically, if it is equal to or higher than the saturated vapor pressure, a liquid phase is formed, and above that, even if the pressure is increased, the water density hardly changes, and therefore no increase in solubility can be expected. Therefore, if it is several atmospheres higher than the saturated vapor pressure, a sufficient dissolution effect can be expected. On the contrary, if the pressure of the aqueous material is too high, the cost for enhancing the pressure resistance of the production apparatus 1 significantly increases, and the deterioration of the extraction means 10 is also likely to occur, which is not preferable.

[0097] The type of heating device for heating the aqueous material is not particularly limited. Examples of the heating device include a heating device that irradiates the aqueous material with microwaves, a heating device that heats the aqueous material by heat conduction from a heating element such as a heater, and the like. By heating the pressurized aqueous material, the aqueous material can be brought into a subcritical state.

[0098] There may be cases where high-temperature steam can be utilized. By using the steam in a heat exchanger or in combination with the above heating device, pressurized water can also be produced. When clean heating steam that does not contain impurities at a temperature higher than the treatment temperature is available, it is also possible to directly introduce the steam. By controlling the pressure with a pressure control valve, the steam can be made into a liquid phase and used as heating water for extraction.

[0099] If the temperature is 70 °C or higher, extraction of crystalline silica contained in the raw material is possible. The saturated vapor pressure of water at 70 °C is about 0.03 MPa, the saturated vapor pressure of water at 100 °C is about 0.1 MPa, the saturated vapor pressure of water at 120 °C is about 0.2 MPa, and the saturated vapor pressure of water at 170 °C is about 0.8 MPa.

[0100] The temperature of the aqueous material after heating is 70 °C or higher. If it is less than 70 °C, even when the raw material liquid and the pressurized aqueous material are brought into contact, there is a possibility that impurities such as crystalline silica and asbestos that may be contained in the raw material cannot be sufficiently dissolved or removed by reaction modification, which is not preferable.

[0101] Since the dissolution or reaction modification and removal of impurities such as crystalline silica and asbestos that may be contained in the raw material can proceed more preferably, the temperature of the aqueous material after heating is preferably 100 °C or higher, more preferably 120 °C or higher, and even more preferably 150 °C or higher.

[0102] Also, the temperature of the aqueous material after heating is 370°C or lower, preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower. If the temperature of the aqueous material is too high, the amount of hydroxyl groups on the raw material surface will rather decrease, which is not preferable.

[0103] According to the present embodiment, by using low-temperature heat of 370°C or lower (preferably 300°C or lower, more preferably 250°C or lower, even more preferably 200°C or lower, and particularly preferably 150°C or lower), impurities such as crystalline silica or asbestos can be dissolved and removed by reaction, so it is even more excellent in terms of manufacturing cost. As the low-temperature heat, not only the heat from the heat source device but also the reuse of waste heat in the factory can be considered.

[0104] [Contact between the raw material liquid and the aqueous material] The raw material liquid is charged into the extraction means 10, and then the aqueous material is continuously supplied to the extraction means 10, so that the raw material liquid and the aqueous material come into contact. The raw material liquid is instantaneously heated to the subcritical temperature by the amount of heat possessed by the aqueous material, and the reaction between the raw material liquid and the aqueous material is started. By this reaction, an extraction reaction or a modification reaction of crystalline silica, asbestos, etc. that may be contained in the raw material into the aqueous material starts.

[0105] The shape of the extraction means 10 is not particularly limited as long as it can maintain the subcritical state, which is the extraction condition of crystalline silica into the aqueous material, for a predetermined time. Examples of the shape of the extraction means 10 include a reactor covered with a constant temperature layer such as a spiral tube wound multiple times inside a heating cylinder, a molten salt bath jacket, and a fluidized sand bath.

[0106] By setting the shape of the extraction means 10 as a spiral tube wound multiple times inside a heating cylinder or a reactor covered with a constant temperature layer, temperature changes and temperature unevenness of the mixture of the raw material liquid and the aqueous material due to heat conduction through the device wall surface can be prevented, and precise temperature control required in impurity extraction in the subcritical state can be realized.

[0107] From the outlet of the extraction means 10, a high-temperature and high-pressure fluid in which impurities such as crystalline silica and asbestos are dissolved flows out. Since the solubility, that is, the solution concentration is low, and it is at a relatively low temperature and low pressure, it is also possible to remove it as it is. After extraction, a high-temperature and high-pressure fluid containing magnesium hydrosilicate derived from natural minerals from which impurities have been removed is discharged from the extraction means 10.

[0108] From the viewpoint of appropriately removing impurities such as crystalline silica and asbestos, the time of the hydrothermal reaction treatment reaction in the extraction means 10 is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 10 minutes or more.

[0109] On the other hand, from the viewpoints of production efficiency and suppressing the deterioration of the extraction means 10, and also for reducing the effect of impurity crystal growth due to Ostwald ripening, the time of the hydrothermal reaction treatment reaction is preferably 10 hours or less, more preferably 5 hours or less, and even more preferably 2 hours or less.

[0110] 〔Cooling means 20〕 Providing the cooling means 20 is not essential. The cooling means 20 may be provided as an arbitrary configuration as needed. When it is at a relatively high temperature and high pressure, or the elution concentration is high, there is a risk of damaging the pressure control valve due to the re-precipitation of the dissolved impurities by cooling before the pressure control valve. In such a case, by installing the cooling section 20, the load on the subsequent pressure control valve can be reduced by re-precipitating and removing the dissolved and extracted impurity components.

[0111] Cooling is performed by mixing the high-temperature and high-pressure fluid supplied from the extraction means 10 with a low-temperature and high-pressure aqueous material pressurized by a pressure pump or the like. By mixing the high-temperature and high-pressure fluid with the low-temperature and high-pressure fluid, the heat quantity accompanying the state change of the fluid, that is, the heat quantity corresponding to the latent heat of evaporation, can be quickly removed, and safe and stable operation can be performed. Furthermore, if the high-temperature and high-pressure fluid is cooled below the critical temperature by this mixing, the high-temperature and high-pressure fluid can be rapidly cooled, and the reaction that generates particles can be stopped almost instantaneously. Therefore, the particles as the product can be made to have a substantially uniform particle size.

[0112] When operating at low temperatures, such a cooling method may be sufficient. However, when operating at relatively high temperatures, heat recovery may be required from the perspective of energy utilization. In that case, a cooling pipe is installed to perform indirect cooling, i.e., heat exchange, and the recovered heat is used for preheating the raw material or the circulating water.

[0113] Regarding the recovery of particles from the extraction tank 10, when the container is charged with powder, it is recovered as it is. When recovering in slurry form, the product particle-containing fluid is separated into product particles and fluid through a filter. The type of filter is not particularly limited, and for example, an in-line filter can be mentioned. The filter can collect magnesium silicate hydrate derived from natural minerals from which impurities have been removed.

[0114] In the semi-batch operation, since impurities are dissolved and removed, the cooling operation of the extractor 10 is not important. However, when this system is operated in a batch operation, due to cooling, the dissolved impurities will precipitate on the product, which is the silicate mineral. In that case, if the cooling rate is slow, re-precipitation of the crystalline component may occur, so the cooling operation of the entire apparatus becomes important.

[0115] <Silicate mineral> The average particle diameter of the silicate mineral obtained as a product is preferably 100 nm or more. When the raw material is a natural mineral, the silicate mineral is provided by pulverizing the natural mineral. Therefore, it is difficult to make the average particle diameter less than 100 nm, and for the product after the hydrothermal reaction treatment, the average particle diameter is also 100 nm or more.

[0116] From the perspective of the safety of talc users, the average particle diameter is more preferably 200 nm or more, even more preferably 500 nm or more, still more preferably 1 μm or more, and particularly preferably 5 μm or more.

[0117] Generally, when using natural talc minerals, they are often pulverized and classified by sieving. In that case, the particle size further becomes as large as several tens of μm or more. In the case of finer particles, a gas-phase classification method is used, but in that case too, generally it is about several μm, and as a special example, sub-μm particle recovery is also possible.

[0118] In the present invention, the average particle size refers to the median diameter D50 by the centrifugal sedimentation method measured according to JIS R1619.

[0119] Also, from the viewpoint of the efficiency of industrial production, the lower limit of the treatment concentration of the silicate mineral is preferably 1% by weight or more, more preferably 3% by weight or more. The upper limit of the treatment concentration of the silicate mineral is preferably 30% by weight or less, more preferably 20% by weight or less. Among them, even when the concentration of impurities (crystalline silica and asbestos) in the silicate mineral is relatively high, the upper limit of the treatment concentration of the silicate mineral is more preferably 10% by weight or less, and particularly preferably 5% by weight or less in terms of being able to appropriately treat the impurities.

[0120] Also, the content of crystalline silica in the silicate mineral obtained as a product is 0.1% by weight or less, more preferably 0.08% by weight or less, more preferably 0.05% by weight or less, and even more preferably below the detection limit.

[0121] Also, the content of asbestos in the silicate mineral powder obtained as a product is 0.1% by weight or less, more preferably 0.08% by weight or less, more preferably 0.05% by weight or less, and even more preferably below the detection limit.

[0122] In the present embodiment, the contents of crystalline silica and asbestos are determined using an X-ray diffractometer. At that time, the conditions of the X-ray diffractometer are as follows. Tube voltage: 45 kV Tube current: 200 mA Anticathode: Cu Monochromatization: Graphite monochromator Detector: Scintillation counter SC-70S Slit system: Light-receiving slit box 1 1.000 mm Light-receiving slit box 2 1.125 mm Incident slit box 1.000 mm Longitudinal limiting slit 15 mm Goniometer scanning speed: 0.10° per minute Full scale of chart: For the intensity measurement of the diffraction line, the net peak area obtained by subtracting the background is determined. Select an appropriate full scale on the recording chart so that the diffraction line can be confirmed as a peak.

[0123] The X-ray diffractometer can be set to these conditions if it is, for example, SmartLab 9MTP (manufactured by Rigaku Corporation).

[0124] Among crystalline silica, the content of quartz shall be determined from the peak intensity at a diffraction angle (2θ) of 26.6° using a calibration curve obtained using a standard quartz sample in powder X-ray diffraction. Also, the content of cristobalite shall be determined from the peak intensity at a diffraction angle (2θ) of 22.0° using a calibration curve obtained using a standard cristobalite sample in powder X-ray diffraction. Also, the content of tridymite shall be determined from the peak intensities at diffraction angles (2θ) of 20.5° and 21.6° using a calibration curve obtained using a standard tridymite sample in powder X-ray diffraction.

[0125] Among asbestos, the content of tremolite shall be determined from the peak intensity at a diffraction angle (2θ) of 10.4° using a calibration curve obtained using a standard tremolite sample in powder X-ray diffraction. Also, the content of chrysotile shall be determined from the peak intensities at diffraction angles (2θ) of 12.1° and 24.3° using a calibration curve obtained using a standard chrysotile sample in powder X-ray diffraction.

[0126] Others shall comply with the "8.4.3.1. Analysis Method for Asbestos Content in Talc" of the Asbestos Analysis Manual for Prior Investigation Based on the Asbestos Act [Version 1.20], March 2018, Ministry of Health, Labour and Welfare.

[0127] Generally, in the measurement of trace components, the measurement peak may be hidden in the baseline noise. Therefore, in order to increase the signal / noise ratio, it is necessary to set a long integration time. As a result, even without using a strong radiation source, trace detection is in principle possible with a normal XRD analyzer. In the invention described in this embodiment, a long-time measurement is performed with sufficient consideration of this point, and the analysis is carried out based on the calibration curve created based on the precise baseline evaluation. As a result, crystalline silica or asbestos is dissolved and removed from the aqueous material, and the asbestos content is truly reduced to 0.1 wt% or less. That is, while conforming to the judgment result by a general-purpose X-ray diffractometer as defined in the attached table of Kikanhua Fa No. 0828001, it is confirmed that the safety standard in the attached table is achieved with sufficient accuracy by making full use of precise analysis methods.

[0128] Whether the product is a silicate mineral powder or not shall be determined from the diffraction peaks in powder X-ray diffraction. For example, whether the product is hydrated magnesium silicate powder (talc powder) or not shall be determined by whether there are diffraction peaks at diffraction angles (2θ) of 9.45°, 18.97°, and 28.62° in the powder X-ray diffraction by the above-described precise analysis method.

[0129] Also, the amount of the NaOH aqueous solution (0.01 M) required in the following method (Shear's method) is preferably 180 μl or more, and more preferably 200 μl or more. (1) Disperse 0.1 g of silicate mineral powder in 10 ml of water. (2) Add 2 g of NaCl, and then adjust the pH to 4 or less with dilute hydrochloric acid (0.12 M). (3) Add the NaOH aqueous solution (0.01 M), and after adjusting the pH to 4, measure the required amount of the NaOH aqueous solution (0.01 M) until the pH reaches 9.

[0130] By hydrothermally treating natural talc, the amount of OH groups on the surface increases. Also, the amount of OH groups increases with an increase in the hydrothermal temperature. The presence or absence of hydrothermal treatment also affects wettability. By hydrothermally treating natural talc, the contact angle becomes smaller. This means that the wettability has improved, that is, the hydrophilicity has been enhanced. Thus, it can be said that by hydrothermally treating a silicate mineral, the affinity with a polar solvent for cosmetics is improved and the compatibility is enhanced.

[0131] When the silicate mineral obtained by the present invention is magnesium silicate hydrate powder, the magnesium silicate hydrate powder is used in the plastic field (filler (improvement of rigidity, heat resistance, dimensional stability), crystal nucleating agent), paper-making field (filler, pitch control agent, coating agent), paint field (extender pigment (adjustment of viscosity and gloss), powder paint), electronic component field (laminated board, molded product, resist ink, adhesive), ceramics field (glaze of ceramics, raw material of honeycomb ceramics), rubber field (filler (improvement of heat resistance, reinforcement, etc.), mold release agent), cosmetics field (foundation, body powder, baby powder, eyeshadow, lipstick), sanitary product field (baby powder; prevention of baby's sweat and rash, etc.), pharmaceutical field (excipient of tablets, lubricant, lubricant for medical rubber gloves), food field (gum base, manufacturing aid (anti-sticking)), agricultural field (anti-caking agent for fertilizers, carrier for agricultural chemicals), etc. In particular, since it has high safety at a level corresponding to synthetic talc, the magnesium silicate hydrate powder obtained by the present invention is preferably applied to the cosmetics field, sanitary product field, pharmaceutical field and / or food field.

[0132] For example, when applied to the cosmetics field, the cosmetic composition may contain, in addition to the silicate mineral of the present invention, various components exemplified by a colorant, extender pigment, brightening agent, oily component, humectant, surfactant, thickener, preservative, ultraviolet light scattering agent, antioxidant, and chelating agent, as required.

[0133] Examples of the colorant include, but are not limited to, inorganic pigments, organic pigments, dyes, natural pigments, etc.

[0134] Examples of extender pigments include, but are not limited to, inorganic powders such as silica, mica, synthetic fluorophlogopite, glass powder, barium sulfate, kaolin, bentonite, hectorite, zeolite, bismuth oxychloride, zirconium oxide, magnesium oxide, aluminum oxide, calcium sulfate, barium sulfate, magnesium sulfate, calcium carbonate, magnesium carbonate, and talc. Furthermore, silicone elastomers such as nylon, polyethylene, (vinyl dimethicone / methicone silsesquioxane) copolymer, dispersants such as polymethyl methacrylate, lauroyl lysine, silk powder, cellulose powder, polyvalent metal salts of long-chain fatty acids, and organic powders such as various wax powders are included, but not limited to these."

[0135] Examples of brighteners include, but are not limited to, those in which the surfaces of plate-like powders such as mica, synthetic fluorophlogopite, glass, silica, and alumina are coated with colorants such as titanium oxide, iron oxide, silicon oxide, ultramarine, chromium oxide, tin oxide, chromium hydroxide, gold, silver, carmine, organic pigments such as Red No. 202 and Yellow No. 4, and those obtained by cutting film blanks such as polyethylene terephthalate / polymethyl methacrylate laminate powder, polyethylene terephthalate / aluminum vapor-deposited powder, and polyethylene terephthalate / gold vapor-deposited laminate powder into arbitrary shapes."

[0136] As the oily component, for example, hydrocarbon oil, ester oil, wax, higher alcohol, animal and vegetable oils, etc. can be used. Examples of hydrocarbon oil include squalane, dodecane, tetradecane, hexadecane, etc. Examples of ester oil include phytosteryl macadamia nut fatty acid, octyldodecyl myristate, glyceryl tri(caprylate / caprate), stearyl stearate, methylheptyl isostearate, hexyl laurate, isoacyl laurate, (capric acid / caprylic acid) palm alkyl, isocetyl myristate, isostearyl isostearate, etc. Examples of wax include beeswax, candelilla wax, carnauba wax, rice bran wax, sunflower seed wax, candelilla wax, gay wax, montan wax, etc. Examples of higher alcohol (monohydric alcohol with 6 or more carbon atoms) include cetyl alcohol, stearyl alcohol, isostearyl alcohol, lauryl alcohol, behenyl alcohol, etc. Examples of animal and vegetable oils include avocado oil, linseed oil, almond oil, olive oil, cocoa butter, sesame oil, wheat germ oil, safflower oil, jojoba oil, phytosteryl macadamia nut fatty acid, shea butter, turtle oil, camellia oil, peach kernel oil, castor oil, grape seed oil, macadamia nut oil, coconut oil, rose hip oil, soybean oil, egg yolk oil, hydrogenated castor oil, hydrogenated coconut oil, hydrogenated cocoa butter, hydrogenated turtle oil, hydrogenated mink oil, beef tallow, mink oil, lanolin (wool fat), and oily components extracted from these components, but are not limited thereto.

[0137] As the humectant, for example, polyhydric alcohols such as glycerin, 1,3-butylene glycol, propylene glycol, polyethylene glycol, diglycerin trehalose; high molecular compounds such as sodium hyaluronate, heparin analogs, sodium chondroitin sulfate, collagen, elastin, keratin, chitin, chitosan; amino acids such as glycine, aspartic acid, arginine; natural moisturizing factors such as sodium lactate, urea, sodium pyrrolidonecarboxylate; lipids such as ceramide, cholesterol, phospholipid; plant extractives such as chamomile extract, witch hazel extract, tea extract, perilla extract, etc., but are not limited thereto.

[0138] As the surfactant, an anionic surfactant, a cationic surfactant, a nonionic surfactant, or an amphoteric surfactant can be used. For example, polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, monocetyl glyceryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene derivatives such as polyoxyalkyl allyl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene hydrogenated castor oil, and polyoxyethylene lanolin; sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monooleate, sorbitan sesquioleate, and sorbitan monostearate; polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monooleate; polyoxyethylene sorbitol fatty acid esters such as polyoxyethylene sorbitol tetraoleate; polyethylene glycol fatty acid esters such as polyethylene glycol monolaurate and polyethylene glycol monooleate; alkyl glyceryl ethers such as isostearyl glyceryl ether; and glycerin fatty acid esters such as glyceryl monobehenate. One or more selected from these can be mentioned. Anionic surfactants such as fatty acid monocarboxylates, polyoxyethylene alkyl ether acetates, alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, stearoyl methyl taurine and its salts; amphoteric surfactants such as fatty acid amide propyl betaine, alkyl imidazolium betaine, alkyl dimethylaminoacetate betaine, alkyl dimethyl sulfobetaine, alkyl dimethylamine oxide, and alkyl hydroxy sulfobetaine. One or more selected from these can be mentioned, but it is not limited thereto.

[0139] Examples of the thickener include, but are not limited to, guar gum, locust bean gum, carrageenan, xanthan gum, carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydrophobized hydroxypropyl methyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, carboxyvinyl polymer, acrylic acid / alkyl methacrylate copolymer, polyethylene glycol, bentonite, (hydroxyethyl acrylate / sodium acryloyldimethyltaurate) copolymer, (ammonium acryloyldimethyltaurate / vinyl pyrrolidone) copolymer, etc.

[0140] Examples of the preservative include, but are not limited to, benzoic acid, sodium benzoate, dehydroacetic acid, sodium dehydroacetate, isobutyl p-hydroxybenzoate, isopropyl p-hydroxybenzoate, butyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, methyl p-hydroxybenzoate, phenoxyethanol, chlorobutanol, chlorhexidine, salicylic acid, benzalkonium chloride, cetyltrimethylammonium bromide, acrinol, benzethonium chloride, cresol, gluconic acid and its derivatives, povidone iodine, potassium iodide, iodine, isopropylmethylphenol, triclocarban, triclosan, photosensitizer No. 101, photosensitizer No. 201, parabens, phenoxyethanol, 1,2-pentanediol, alkyldiaminoglycine hydrochloride, pyrithione zinc, miconazole, etc.

[0141] Examples of the ultraviolet absorber include, but are not limited to, para - aminobenzoic acid, glyceryl para - aminobenzoic acid, ethyl dihydroxypropyl para - aminobenzoic acid, octyl dimethyl para - aminobenzoic acid, amyl para - dimethylaminobenzoate, hexyl diethylaminohydroxybenzoyl benzoate, methyl anthranilate, homomenthyl salicylate, 2 - ethylhexyl salicylate, triethanolamine salicylate, 2 - ethylhexyl paramethoxycinnamate, glyceryl diparamethoxycinnamate mono - 2 - ethylhexanoate, methyl 2,5 - diisopropylcinnamate, methyl trimethoxycinnamate bis(trimethylsiloxy)silyl isopentyl, isopropyl paramethoxycinnamate, isopropyl paramethoxycinnamate - diisopropylcinnamate ester mixture, 2 - ethoxyethyl paramethoxycinnamate, diethanolamine salt of paramethoxycinnamic acid, 4 - isopropyldibenzoylmethane, 4 - tert - butyl - 4'-methoxydibenzoylmethane, 2,4,6 - tris[4 - (2 - ethylhexyloxycarbonyl)anilino]-1,3,5 - triazine, 2,4 - bis - [{4 - (2 - ethylhexyloxy)-2 - hydroxy}-phenyl]-6 - (4 - methoxyphenyl)-1,3,5 - triazine, 2,4 - dihydroxybenzophenone, 2,2'-dihydroxy - 4 - methoxybenzophenone, 2 - hydroxy - 4 - methoxybenzophenone, 2,2'-dihydroxy - 4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 4 - (2 - β - glucopyranosyloxy)propoxy - 2 - hydroxybenzophenone, 2 - hydroxy - 4 - n - octyloxybenzophenone, 2 - ethylhexyl dimethoxybenzylidene dioxoimidazolidine propionate, octocrylene, cinoxate, phenylbenzimidazole sulfonic acid, 1 - (3,4 - dimethoxyphenyl)-4,4 - dimethyl - 1,3 - pentanedione, 3 - (4 - methylbenzylidene)camphor, methylene bisbenzotriazolyl tetramethylbutylphenol, etc.

[0142] Examples of the ultraviolet scattering agent include, but are not limited to, titanium oxide, zinc oxide, cerium oxide, etc.

[0143] Examples of antioxidants include, but are not limited to, natural vitamin E, tocopherol, dibutylhydroxytoluene, butylhydroxyanisole, sorbic acid, sodium sulfite, ascorbic acid, erythorbic acid, L-cysteine hydrochloride, etc. Examples of pH adjusters include, but are not limited to, inorganic acids (hydrochloric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, boric acid, etc.), organic acids (lactic acid, acetic acid, citric acid, sodium citrate, tartaric acid, malic acid, succinic acid, sodium succinate, oxalic acid, gluconic acid, fumaric acid, propionic acid, acetic acid, aspartic acid, ε-aminocaproic acid, glutamic acid, aminoethylsulfonic acid, etc.), gluconolactone, ammonium acetate, inorganic bases (sodium bicarbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, etc.), organic bases (monoethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, lysine, etc.).

[0144] Examples of chelating agents include, but are not limited to, ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetate (sodium salt (sodium edetate: Japanese Pharmacopoeia, EDTA-2Na, etc.), potassium salt, etc.), phytic acid, gluconic acid, polyphosphoric acid, metaphosphoric acid, etc.

[0145] As for the colorants and extender pigments described above, those whose surfaces have been treated with a surface treatment agent can be used as needed. Examples of the surface treatment agent include, but are not limited to, fluorine compound treatment, silicone treatment, silicone resin treatment, pendant treatment, silane coupling agent treatment, titanium coupling agent treatment, oil agent treatment, metal soap treatment, N-acylation lysine treatment, polyethylene glycol treatment, PVA treatment, polyacrylic acid treatment, hyaluronic acid treatment, alginic acid treatment, inorganic compound treatment, urethane crosslinked polymer treatment, plasma treatment, mechanochemical treatment, etc. Among them, metal soap treatment and urethane crosslinked polymer treatment are preferred. As the metal soap treatment, aluminum dimyristate treatment, aluminum stearate treatment, aluminum distearate treatment, etc. are used, and as the urethane crosslinked polymer treatment, (HDI / trimethylolhexyl lactone) cross-polymer treatment can be preferably used.

[0146] Furthermore, heretofore, the formation of minerals underground has been precipitation due to the temperature and pressure, and the precipitate composition varies depending on the location where the minerals are mined. Selecting and using a portion that contains almost none of the above impurities through scrutiny has been regarded as the only solution. However, according to the present invention, even if the raw material contains impurities exceeding the specified value, there is a possibility that the impurity content can be made less than the specified value. In this regard, the present invention has great advantages for silicate mineral processing companies and sales companies.

[0147] In the present invention, the term "article containing a silicate mineral" means both the case where a silicate mineral is contained in a composition and the case where a silicate mineral is attached to an article. For example, the "pharmaceutical containing a silicate mineral" means both the case where silicate mineral powder is contained in a pharmaceutical composition as an excipient or lubricant for tablets and the case where silicate mineral powder is attached to a medical rubber glove.

Examples

[0148] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

[0149]

Table 2

[0150]

Table 3

[0151] <Test Example 1> Hydrothermal Reaction Treatment of Natural Talc Containing Quartz 〔Hydrothermal Reaction Treatment of Natural Talc〕 The test was conducted using a batch tester (device name: Oscillating Reactor Heating Stirring Device, manufactured by AKICO Co., Ltd.). 0.45 g (concentration: 10% by weight) of natural talc with an average particle diameter of 5 μm and containing quartz as an impurity and 4 ml of H2O were added to a 5-ml Inconel container, mixed well, and then subjected to hydrothermal reaction treatment for 10 minutes under the conditions shown in Table 2 using a batch tester. After cooling, the processed talc was obtained by thorough washing with water.

[0152] 〔Evaluation〕 When the processed talc after hydrothermal reaction treatment was touched with a finger, it had the same smoothness as the natural talc before hydrothermal reaction treatment. The average particle diameter of the processed talc after hydrothermal reaction treatment was measured. As a result, the average particle diameter was 5 μm in all examples.

[0153] Also, powder X-ray diffraction was performed on each of the natural talc before hydrothermal reaction treatment and the processed talc after hydrothermal reaction treatment. Figure 2 shows the result of the natural talc before hydrothermal reaction treatment, and Figure 3 shows the result of the processed talc after hydrothermal reaction treatment according to Example 1-1. Table 3 shows the change in the impurity content before and after hydrothermal reaction treatment in each example and comparative example. In both Figure 2 and Figure 3, in powder X-ray diffraction, diffraction peaks are present at diffraction angles (2θ) of 9.45°, 18.97°, and 28.62°. Therefore, it means that the substance after hydrothermal reaction treatment is talc.

[0154] On the one hand, in the vicinity of 2θ = 26.6°, before the hydrothermal reaction treatment, a peak derived from quartz (crystalline silica) appears. From the calibration curve obtained using a standard quartz sample, the talc before the hydrothermal reaction treatment contains 0.11 wt% of quartz. On the other hand, there is no alteration even after the hydrothermal reaction treatment, while the peak derived from quartz has disappeared. That is, in Example 1-1, it was confirmed that quartz could be sufficiently removed.

[0155] Similarly, in Examples 1-2 to 1-13, it was also confirmed that quartz could be sufficiently removed from natural talc. In particular, in Examples 1-10 to 1-13, it was confirmed that quartz could be sufficiently removed from natural talc even when the natural talc had a relatively high impurity content. Also, in Examples 1-6 and 1-7, it was confirmed that quartz could be sufficiently removed from natural talc even when the natural talc concentration in the hydrothermal reaction treatment was relatively high.

[0156] <Test Example 2> Hydrothermal reaction treatment of natural talc containing quartz (pH dependence) Processed talc was obtained by the same method as in Example 1-1, except that nitric acid and sodium hydroxide were used to adjust the pH during hydrothermal treatment to 1.4 (Example 2-1), 2.5 (Example 2-2), 6.4 (Example 2-3), and 12.0 (Comparative Example 2).

[0157] As a result of the evaluation by XRD, a decrease and disappearance of the peak derived from quartz were confirmed in the products obtained during hydrothermal treatment at pH 1.4, 2.5, and 6.4. On the other hand, it was confirmed that the peak derived from quartz remained in the product obtained during hydrothermal treatment at pH 12.0. Since the pH was 9.4 in Example 1-1, it was confirmed that quartz could be removed at a pH lower than that, and conversely, quartz could not be removed when the pH was too high.

[0158] In addition, when the average particle diameter of the primary particles was measured for the products obtained at pH 1.4, 2.5, and 6.4, it was 5 μm in all cases.

[0159] <Test Example 3> Hydrothermal reaction treatment of natural talc containing quartz (addition of Mg ions) To a container made of Inconel, 0.06 g of natural talc (concentration: 1.5% by weight), 3 mg of MgCl2 (concentration 0.075% by weight), and 4 ml of H2O were added, and processed talc was obtained in the same manner as in Example 1-1, except that the hydrothermal reaction time was 240 minutes.

[0160] As a result of the evaluation by XRD, a decrease in the peak derived from quartz was confirmed. Even for natural talc with a relatively high impurity content similar to that of Example 1-5, the same amount of quartz could be reduced even when the hydrothermal reaction temperature was 150°C.

[0161] <Test Example 4> Hydrothermal reaction treatment of natural talc containing impurities different from quartz 〔Example 4-1〕 Hydrothermal reaction treatment of natural talc containing cristobalite Processed talc was obtained in the same manner as in Example 1-1, except that natural talc containing 0.12% by weight of cristobalite, which is a type of crystalline silica, was used as the raw material.

[0162] As a result of the evaluation by XRD, the peak at a diffraction angle (2θ) of 22.0° derived from cristobalite disappeared, and it was confirmed that the content of cristobalite could be reduced to 0.1% by weight or less by the hydrothermal reaction treatment.

[0163] 〔Example 4-2〕 Hydrothermal reaction treatment of natural talc containing tridymite Processed talc was obtained in the same manner as in Example 1-1, except that natural talc containing 0.12% by weight of tridymite, which is a type of crystalline silica, was used as the raw material.

[0164] As a result of the evaluation by XRD, the peaks at diffraction angles (2θ) of 20.5° and 21.6° derived from tridymite disappeared, and it was confirmed that the content of tridymite could be reduced to 0.1% by weight or less by the hydrothermal treatment.

[0165] 〔Examples 4-3 to 4-5〕 Hydrothermal reaction treatment of natural talc containing chrysotile Except for using natural talc containing 0.15% by weight of chrysotile and subjecting it to hydrothermal treatment at 250°C for 10 minutes, 40 minutes, and 120 minutes, processed talc was obtained in the same manner as in Example 1-1.

[0166] As a result of the evaluation by XRD, the chrysotile content was 0.075% by weight (treatment time: 10 minutes), 0.03% by weight (treatment time: 40 minutes), and below the detection limit (treatment time: 120 minutes). It was confirmed that the chrysotile content could be reduced to 0.1% by weight or less by the hydrothermal reaction treatment.

[0167] Generally, chrysotile is a stable substance, but under hydrothermal conditions, dissolution tends to proceed from the tip of the acicular mineral more easily compared to ordinary minerals. However, even if it dissolves, the dissolution of talc may also progress. Therefore, what is important is the dissolution rate, the amount of dissolution, the ratio of the amount of dissolution of talc, and the resulting remaining amount. Considering the dissolution rate and the amount of dissolution of a large amount of silicate minerals, even if the same amount dissolves, it is possible to finally leave only magnesium silicate. This result shows that a sufficient dissolution and removal effect of chrysotile is observed, indicating that it is possible to remove asbestos components from talc.

[0168] <Test Example 5> Hydrothermal reaction treatment of silicate minerals different from natural talc 〔Example 5-1〕 Hydrothermal reaction treatment of magnesium aluminum silicate containing quartz Except for using magnesium aluminum silicate containing 0.12% by weight of quartz as the raw material, processed minerals were obtained in the same manner as in Example 1-1.

[0169] As a result of the evaluation by XRD, since the diffraction peak derived from quartz decreased, it was confirmed that the quartz content could be reduced to 0.04% by weight by hydrothermal treatment.

[0170] 〔Example 5-2〕 Hydrothermal reaction treatment of calcium silicate containing quartz Except for using calcium silicate containing 0.12% by weight of quartz as the raw material, processed minerals were obtained in the same manner as in Example 1-1.

[0171] As a result of the evaluation by XRD, since the diffraction peaks derived from quartz decreased, it was confirmed that the content of quartz could be reduced to 0.04% by weight by hydrothermal treatment.

[0172] 〔Examples 5-3 to 5-4〕 Hydrothermal reaction treatment of magnesium silicate containing quartz Processed minerals were obtained by the same method as in Example 1-1 except that magnesium silicate containing 0.12% by weight of quartz was used as the raw material (the treatment times were 10 minutes and 40 minutes).

[0173] As a result of the evaluation by XRD, since the diffraction peaks derived from quartz disappeared, it was confirmed that the content of quartz could be reduced to 0.01% by weight (treatment time: 10 minutes) and below the detection limit (treatment time: 120 minutes) by hydrothermal treatment.

[0174] <Test Example 6> Relationship between hydrothermal treatment temperature, amount of OH groups on the talc surface, and wettability

Table 4

Table 5

[0175] Processed minerals were obtained by the same method as in Example 1-1 except for the conditions described in Table 4.

[0176] 〔Amount of OH groups on the talc surface〕 The amount of OH groups on the talc surface was evaluated using the Shears method. Specifically, it was carried out according to the following procedure. (1) 0.1 g of the processed mineral was dispersed in 10 ml of water. (2) After adding 2 g of NaCl, the pH was adjusted to 4 or less with dilute hydrochloric acid (0.12 M). (3) An aqueous NaOH solution (0.01 M) was added, and after adjusting the pH to 4, the required amount from that point until the pH reached 9 was examined.

[0177] The results are shown in Table 5. It was confirmed that the amount of OH groups on the surface increased by hydrothermally treating natural talc, and that the amount of OH groups increased with an increase in the hydrothermal temperature.

[0178] 〔Wettability〕 For each of Example 6-2 and Comparative Example 6, talc was uniformly supported on a sample holder for X-ray diffraction. Thereafter, one drop (10 μl) of water was dropped, and the contact angle was observed.

[0179] The results are shown in Table 5. The contact angle decreased slightly by hydrothermally treating natural talc. This means that the wettability improved, that is, the hydrophilicity improved. Thus, it can be said that by hydrothermally treating a silicate mineral, the affinity with a polar solvent for cosmetics is improved and the compatibility is improved.

[0180] <Test Example 7> Application to Makeup Cosmetics 〔Test Example 7-1〕 Application to Powder Foundation A powder foundation was prepared according to the formulation shown in Table 6. In Example 7-1, the hydrothermally treated talc obtained in Example 1-1 was used as the talc. In Comparative Example 7-1, natural talc before hydrothermal treatment according to Example 1-1 was used as the talc.

Table 6

[0181] For the obtained powder foundation, the slurry state, hardness, drop strength, and pick-up amount were evaluated. As a result, it was confirmed that the powder foundation using the hydrothermally treated talc had the same quality as the powder foundation using the non-hydrothermally treated natural talc.

[0182] 〔Test Example 7-2〕 Application to Loose Powder Loose powder was prepared according to the formulation shown in Table 7. In Example 7-2, the hydrothermally treated talc obtained in Example 7-1 was used as the talc. In Comparative Example 7-2, natural talc before the hydrothermal treatment according to Example 1-1 was used as the talc.

Table 7

[0183] For the obtained loose powder, the slurry state, hardness, drop strength, and take-up amount were evaluated. As a result, it was confirmed that the loose powder using the hydrothermally treated talc had the same quality as the loose powder using the non-hydrothermally treated natural talc.

[0184] 〔Test Example 7-3〕 Application to eye blow Two types of eye blows were prepared according to the formulation shown in Table 8. In Examples 7-3-1 and 7-3-2, the hydrothermally treated talc obtained in Example 1-1 was used as the talc. In Comparative Examples 7-3-1 and 7-3-2, natural talc before the hydrothermal treatment according to Example 1-1 was used as the talc.

Table 8

[0185] For the obtained eye blow, the slurry state and the dropping strength were evaluated. As a result, it was confirmed that the eye blow using the hydrothermally treated talc had the same quality as the eye blow using the natural talc without hydrothermal treatment.

[0186] <Test Example 8> Application to Skin Care Cosmetics [Test Example 8-1] Application to Summer Body Lotion A summer body lotion was prepared according to the formulation shown in Table 9. In Example 8-1, the hydrothermally treated talc obtained in Example 1-1 was used as the talc. In Comparative Example 8-1, the natural talc before the hydrothermal treatment according to Example 1-1 was used as the talc.

Table 9

[0187] For the obtained summer body lotion, the slurry state was evaluated. As a result, it was confirmed that the summer body lotion using the hydrothermally treated talc had the same quality as the summer body lotion using the natural talc without hydrothermal treatment.

[0188] [Test Example 8-2] Application to Pore Concealer Lotion A pore concealer lotion was prepared according to the formulation shown in Table 10. In Example 8-2, the hydrothermally treated talc obtained in Example 1-1 was used as the talc. In Comparative Example 8-2, the natural talc before the hydrothermal treatment according to Example 1-1 was used as the talc.

Table 10

[0189] The resulting pore concealer lotion was evaluated for its slurry state. As a result, it was confirmed that the pore concealer lotion using hydrothermally treated talc had the same quality as the pore concealer lotion using non-hydrothermally treated natural talc.

[0190] 〔Test Example 8-3〕 Application to Powder Facial Wash A powder facial wash was prepared according to the formulation shown in Table 11. In Example 8-3, the hydrothermally treated talc obtained in Example 1-1 was used as the talc. In Comparative Example 8-3, natural talc before the hydrothermal treatment according to Example 1-1 was used as the talc.

Table 11

[0191] The resulting powder facial wash was evaluated for its slurry state. As a result, it was confirmed that the powder facial wash using hydrothermally treated talc had the same quality as the powder facial wash using non-hydrothermally treated natural talc.

Explanation of Symbols

[0192] 1 Manufacturing apparatus 10 Extraction means 20 Cooling means

Claims

1. A silicate mineral powder having a crystalline silica content of 0.05% by weight or less and an asbestos content of 0.1% by weight or less.

2. The silicate mineral powder according to claim 1, containing a carbonate.

3. The silicate mineral powder according to claim 1, wherein the average particle diameter of the primary particles is 100 nm or more.

4. A method for producing a silicate mineral powder, comprising a step of subjecting a silicate mineral derived from a natural mineral to warm water treatment, hot water treatment, or hydrothermal reaction treatment at a pH of 4 or more and 9.4 or less, wherein the temperature in the warm water treatment, hot water treatment, or hydrothermal reaction treatment is 120°C or more and 370°C or less, the pressure is equal to or higher than the saturated vapor pressure of water, and the treatment time is 1 minute or more and 10 hours or less.

5. The warm water or the hot water treatment or the hydrothermal reaction treatment is carried out in the coexistence of carbonic acid or CO ２ The method according to claim 4, which is carried out in the coexistence of

6. The method according to claim 4, wherein the warm water treatment, hot water treatment, or hydrothermal reaction treatment is carried out in the coexistence of Mg ions.

7. The method according to claim 4, wherein the warm water treatment, hot water treatment, or hydrothermal reaction treatment is carried out using a batch apparatus or a semi-batch apparatus.

8. The method according to claim 4, wherein the silicate mineral is supplied in a suspended state in water using a flow-through apparatus, and the warm water treatment, hot water treatment, or hydrothermal reaction treatment is carried out.

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