JP5264256B2 - Method for producing sodium silicate solution and method for using sodium silicate solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a sodium silicate solution, in which a sodium-based by-product can be recycled and the sodium silicate solution having a stable component is produced safely from the sodium-based by-product so that the produced sodium silicate solution can be substituted for at least one chemical selected from a land improving agent, a caking agent when a casting mold is manufactured, a deinking agent for used paper, and a stabilizer of hydrogen peroxide when paper or pulp is bleached. <P>SOLUTION: The method for producing the sodium silicate solution comprises the steps of: dissolving the sodium-based by-product in water, which is produced as the by-product from a process for improving purity of silicon, contains silicon and is based on sodium silicate; and further dissolving the silicon contained in the sodium-based by-product to generate hydrogen gas and produce the sodium silicate solution. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a sodium silicate solution by-produced from a silicon purity improving process and using a by-product containing silicon and containing sodium silicate as a main component. In particular, a sodium silicate solution containing by-products containing silicon and containing sodium silicate as a by-product in the process of producing silicon from SiO solids or removing boron from slag from silicon. It relates to the manufacturing method.

  The inventors previously disclosed in Patent Document 1 that metal silicon containing boron as an impurity is heated to a melting point or higher to obtain a molten state, and then a solid mainly composed of silicon dioxide and an alkali carbonate or alkali carbonate. Disclosed is a method for removing boron from silicon, wherein a solid mainly composed of one or both of hydrated salts is added to the molten silicon to form slag and to remove boron in silicon. doing. Furthermore, sodium carbonate, sodium hydrogen carbonate, and hydrates thereof, which are sodium compounds, are listed as alkali carbonates or hydrated salts of alkali carbonates (hereinafter also referred to as a boron removal method).

  In addition, in the Patent Document 2, the present inventors have disclosed in SiO 2 solid, any one of an alkali metal oxide, hydroxide, carbonate, fluoride, or an alkaline earth metal oxide, hydroxide, Carbon dioxide, fluoride, or two or more of these compounds are added, and the resulting mixture is heated to a temperature equal to or higher than the melting point of Si to cause a chemical reaction, thereby generating Si. Disclosed is a Si production method characterized by separating and recovering from a product. In addition, sodium is cited as one of the alkali metal elements here (hereinafter also referred to as SiO method).

  The present invention mainly relates to the case where a sodium compound is used in the above two methods.

When a sodium compound is used, in the above-described method for removing boron from silicon, in addition to silicon, a glassy substance mainly composed of SiO ₂ and sodium oxide, that is, a by-product mainly composed of sodium silicate is used. Occur. In addition, when a sodium compound is used, in the method for producing silicon from the above-mentioned SiO solid, in addition to silicon, a glassy substance composed of sodium oxide formed from SiO ₂ and the added sodium compound, that is, sodium silicate is used. A by-product containing the main component is generated. These by-products are generated at a mass equal to or higher than that of silicon, and a method for effectively utilizing these by-products has been demanded.
JP 2005-247623 A JP 2004-51453 A

  Since sodium-based by-products are mainly composed of sodium silicate, they are used as ground improvers, binders for mold making, deinking waste paper, and stabilizers for hydrogen peroxide when paper and pulp are drifting. It may be used as a water glass alternative.

  Therefore, when the sodium-based by-product was dissolved in water to make it into a solution, it was found that the sodium-based by-product showed good solubility, but the metal silicon contained in the sodium-based by-product, etc. It was found that the component composition of the sodium silicate solution that can be produced is unstable due to the presence of. Moreover, it turned out that it becomes the cloudy crude sodium silicate solution which has very dark brown or gray.

When a sodium-based by-product is dissolved in water, a solution containing sodium silicate as a main component is obtained (Formula 1). Metallic silicon in the sodium-based by-product reacts with water to generate hydrogen gas, and while increasing the molar ratio of the sodium silicate solution (SiO ₂ / Na ₂ O, hereinafter simply referred to as molar ratio), silicic acid It becomes a sodium solution.

mSi + Na ₂ O.nSiO ₂ +2 mH ₂ O → Na ₂ O. (n + m) SiO ₂ +2 mH ₂ ↑ ――― (Formula 1)

  Since hydrogen is an explosive gas, it was necessary to deal with this hydrogen in order to use sodium-based by-products in industrial production lines.

In addition, the molar ratio of the sodium-based by-product (SiO ₂ / Na ₂ O) varies depending on whether the silicon purity improvement process is a boron removal method or an SiO method, and the operating conditions of the process. It takes a value in the range of about ~ 5, and usually takes a value in the range of about 0.5 to 2.5.

If the variation of the metal silicon content in the sodium-based byproduct is small, the molar ratio of the sodium silicate solution (SiO ₂ / Na ₂ O) does not vary greatly. However, the metal silicon content in the sodium-based by-product may vary depending on the operating conditions, in which case the sodium silicate SiO ₂ / Na ₂ O (molar ratio) in the solution becomes unstable.

  Moreover, the form of silicon in the sodium-based by-product is a form in which a mass of several mm to several tens of mm is bitten in places of the sodium-based by-product, but as another form, It has been found that there is always a very fine form, possibly as small as several μm or less, dispersed in a sodium-based byproduct. This presence is considered to cause the color of the sodium-based by-product to be brown or gray. The reason why the fine silicon is colored is not clear, but the fine silicon is not limited to being present as a metal, but at least the surface may be oxidized or zeolitic, and it is colored. It is estimated to be.

  Therefore, whether or not silicon is contained in the sodium-based by-product can be easily distinguished from this color. This is because sodium silicate as a main component of the sodium-based by-product is colorless and transparent, but fine silicon particles of about several μm are brown or gray.

  Some of the fine silicon is insoluble. For example, it is considered that the surface has been oxidized or zeoliticized, but when they become vitrified water, they cause suspended substances.

  In addition, in the method for producing silicon from SiO solid or the method for removing boron by slag refining from silicon, the source is not clarified, but there are a small amount of impurities such as furnace materials, members, and heat insulating materials. Is dissolved or mixed in the sodium-based by-product.

Further, at the time of production of the sodium silicate solution to be described later, the strength for an alkaline condition, these furnace material, member, contaminants (such as Al ₂ O ₃ and MgO and CaO) from such heat insulating material, these compounds while trace Dissolves. The dissolved trace amount of polyvalent metal ions such as Ca, Mg and Al reacts with the sodium silicate solution to simultaneously generate insoluble silicate metal hydrate and silicic acid, which gels and is suspended in the sodium silicate solution. It becomes a turbid substance. For example, the reaction with calcium hydroxide is as shown in (Formula 2).

Na ₂ O · nSiO ₂ + Ca (OH) ₂ + mH ₂ O → CaO · nSiO ₂ · mH ₂ O · 2NaOH (partially becomes SiO ₂ )
――― (Formula 2)

If the total amount of Al ₂ O ₃ , MgO and CaO components in the sodium-based by-product is low (for example, 0.05% or less), the amount of generated suspended matter is small, and the suspended matter is deliberately I think there is no need to separate. The insoluble silicon in the sodium-based by-product is considered to be a very small amount and cannot be measured substantially.

  However, the content of impurities in the sodium-based by-product varies greatly, and the concentration often has a value not less than a value (for example, 0.05% or more) at which the turbidity due to the suspended substance becomes a problem.

In addition, in order to use the sodium silicate solution to be produced as a substitute for the above-mentioned ground improver, slag solidifying agent, deinking agent, etc., SiO ₂ / Na ₂ O ( It was found that it was necessary to suppress fluctuations in the molar ratio and to reduce the turbidity.

First, the use application of the generally used sodium silicate solution will be described.
Usually, a transparent sodium silicate solution having a SiO ₂ / Na ₂ O (molar ratio) of 1 to 4 is called water glass, and is one of the injection materials used in the chemical solution injection method in the soil soil improvement method. Used, binder for mold, auxiliary agent for soap and synthetic detergent, silica gel raw material, auxiliary agent for vancous sulfate as flocculant, building material, heat insulating material, deinking waste paper, peroxidation when paper / pulp strays It is used as a hydrogen stabilizer.

  Next, the water glass type injection material using sodium silicate (water glass) used in the chemical solution injection method in the improved soil ground will be described.

  The water glass used in the chemical injection method is not used alone but is mixed with various chemicals and is called a water glass injection material.

  There are two types of water glass injection material: solution type and suspension type. The solution type can be classified into a total of four types, that is, two types of inorganic and organic types depending on the reaction material, and two types of acidic silica sol and colloidal silica depending on the processing form of the main material water glass. In addition, the suspension type includes a mixture due to cement mixing, and another suspension, that is, a mixture containing a sparingly soluble calcium-based material.

  As reaction materials in the solution type, those generally used as inorganic acids are phosphoric acid, sodium hydrogen carbonate, sodium hydrogen sulfate, sodium phosphate, sodium hydrogen sulfite and the like. Similarly, alkaline earth metal salts include calcium chloride. Sodium chloride, magnesium chloride, aluminum sulfate, magnesium sulfate and the like are used. Examples of the organic reaction material include glyoxal, polyhydric alcohols, ethyl acetate, and ethylene carnate.

  Moreover, the thing which processed water glass as a main material and improved it is the acidic silica gel which makes silica gel by making acidic sol of water glass using an inorganic strong acid, and adding an alkali material to it. This is usually done by bringing in a device to create an acidic sol on site. Colloidal silica, on the other hand, uses an ion exchange resin at the factory to remove the alkali of water glass to make a silica colloid, bring it into the field, break the electric double layer on the surface of the colloid, and colloidally bond it. Is to make.

  In the suspension type, turbidity of water glass itself does not become a big problem because cement and poorly soluble calcium-based material are mixed. However, in the case of solution-type water glass-based injection material, the injection material is grounded by press-fitting. It often infiltrates through the interstices of the soil particles therein, and it may cause a problem if the turbidity is large or the particle size of the suspended particles is large.

  Therefore, in the case of a solution-type water glass-based injection, it is necessary to manage to some extent the amount of suspended matter and the particle size in the water glass to be used.

Water glass injection material injected into the ground expels pore water in the gap between soil particles, fills the gap with water glass injection material, and water glass reacts to generate mesh-like or spherical silica gel etc. . As a result, the hydraulic conductivity of the ground decreases, increasing the adhesive strength of the ground and increasing the strength of the ground. Many of the purposes of the chemical solution injection method are to reduce the water permeability coefficient to the order of 10 ⁻⁴ cm / sec, and to prevent or stop water.

  When the concentration of silicic acid in the water glass injection varies, the concentration of silicic acid in the gap between soil particles also changes, so the amount of products such as silica gel in the gap changes, and the hydraulic conductivity of the entire ground decreases as planned. There are things that do not. In this case, it is often possible to achieve a predetermined construction quality by injecting the injection material again, but this increases the cost and the number of days. Therefore, it is necessary to suppress the fluctuation of the silicic acid concentration in the water glass-based injecting agent used as the ground improvement material to some extent.

Therefore, in order to use the sodium silicate solution produced in the present invention as a ground improvement agent, it is necessary to penetrate into the ground. In order to permeate the gaps between the soil particles constituting the ground, the 90% particle diameter of the suspended substance is preferably 200 μm or less, more preferably 100 μm or less. Alternatively, the turbidity is preferably 5000 mg / L or less. Furthermore, it is more preferable that the 90% particle diameter of the suspended substance is 100 μm or less and the turbidity is 500 mg / L or less. As for the fluctuation range of the silicic acid concentration, the fluctuation range with respect to the average value of the silicic acid concentration is less likely to affect the construction quality, but the fluctuation range of the silicic acid concentration in No. 1, No. 2, No. 3 water glass is According to JIS K1408, the fluctuation range is 5 to 9% with respect to the average value, and this range is more preferable. For that purpose, in order to use the sodium silicate solution produced in the present invention as a ground improvement material, it is important to control the liquid specific gravity and SiO ₂ / Na ₂ O (molar ratio). The liquid specific gravity can be controlled by measuring the liquid specific gravity and adjusting the water content when a sodium silicate by-product or silicon slag is dissolved in water and a sodium silicate solution is prepared. Since for the Control of SiO ₂ / Na ₂ O (molar ratio), SiO ₂ / Na ₂ O in the slag after separation of the silicon (molar ratio) is from 1.5 to 2.5, sodium-based By separating the silicon in the by-product, the reaction shown in the above (Formula 1) is reduced, the fluctuation of SiO ₂ / Na ₂ O (molar ratio) is suppressed, and the fluctuation range of the silicic acid concentration in the sodium silicate solution Is about 10% of the average value.

Next, sodium silicate (water glass) used other than the ground improvement material will be described.
When used as a binder for a mold, the mold needs to have a certain degree of strength, and thus it is necessary to suppress the fluctuation of the silicic acid concentration to some extent. Further, when used as a deinking agent for waste paper, it is necessary to suppress turbidity to some extent in order to use it in the deinking process. In addition, when used as a stabilizer for hydrogen peroxide at the time of paper / pulp stray, it is necessary to suppress turbidity to some extent.

That is, by controlling the silicic acid concentration fluctuation, suppressing the fluctuation of SiO ₂ / Na ₂ O (molar ratio), maintaining the low turbidity value, and controlling the 90% particle size in the suspended substance, The sodium silicate solution can be used as a ground improvement material, a caking additive for molds, a deinking material for waste paper, and a stabilizer for hydrogen peroxide when floating on paper and pulp.

  Therefore, in order to dissolve the slag generated by silicon production and use it as a sodium silicate solution, (a) prevention of explosion risk associated with hydrogen generation, (b) ensuring the stability of the component, (c) It has been found that there is a new problem to be solved, suppression of turbidity.

  In the present invention, the above problems are solved, sodium-based byproducts can be recycled, sodium silicate solution having a stable component is safely produced from sodium-based byproducts, and the solution is further improved in the ground. To provide a method for producing a sodium silicate solution that can be used as a substitute for any one of an agent, a binder used in mold making, a deinking agent for used paper, and a stabilizer for hydrogen peroxide when floating on paper and pulp. Objective.

When a sodium-based by-product is dissolved in water, a solution containing sodium silicate as a main component is obtained. Metallic silicon in the sodium-based by-product reacts with water to generate hydrogen gas, and becomes a sodium silicate solution while increasing the molar ratio (SiO ₂ / Na ₂ O) of the sodium silicate solution.

First, when the metal silicon content in the sodium-based by-product is small, or when the fluctuation of the metal silicon content is small, the amount of change in the molar ratio of the sodium silicate solution (SiO ₂ / Na ₂ O) can be reduced, When the metal silicon content is low, the amount of hydrogen gas generated is also small. In addition, when the content of impurities in the sodium-based by-product is small, the turbidity can be reduced (5000 mg / L or less), the sodium silicate solution can be used as a ground conditioner, a caking agent for molding, a deinking agent for waste paper, It is possible to provide a replacement for any one of the stabilizers for hydrogen peroxide when paper and pulp are drifting.

Next, when the metal silicon content varies greatly and the molar ratio of the sodium silicate solution (SiO ₂ / Na ₂ O) varies greatly, the metal silicon is separated in advance, so that the molar ratio of the sodium silicate solution (SiO 2 _The means for stabilizing ₂ / Na ₂ O) and suppressing the generation of hydrogen gas will be described.

A sodium-based byproduct is poured into water, and metal silicon in the sodium-based byproduct reacts with water (alkaline) to generate hydrogen gas and increase the internal pressure at the silicon-slag interface, etc. By disintegrating by-products and allowing the silicon gas to selectively float from the water by attaching hydrogen gas generated around the silicon in the alkaline aqueous solution as bubbles to the silicon, the silicon is effectively levitated and sodium silicate Can be efficiently recovered. About water temperature, 60 degreeC or more which a sodium-type by-product tends to collapse is good. Thereby, by stabilizing the metal silicon content at a low level, an increase in the molar ratio of the sodium silicate solution (SiO ₂ / Na ₂ O) is suppressed, and the molar ratio of the sodium silicate solution (SiO ₂ / Na ₂ O) Stabilizes. That is, by separating the metal silicon from the slag, a sodium silicate solution can be produced safely and stably in a molar ratio (SiO ₂ / Na ₂ O) while reducing the generation of hydrogen gas.

  Next, means for separating suspended substances when the content of impurity components in the sodium-based by-product varies greatly, the content is 0.05% or more, and the turbidity in the sodium silicate solution is large. Is described.

  In order to provide sodium silicate solution as an alternative to any one of ground improvement agent, binder for mold making, deinking agent for waste paper, and stabilizer for hydrogen peroxide when floating paper and pulp, It is necessary to maintain the permeability to the ground, maintain the binding force, reduce the impurity content, etc., and make the turbidity 5000 mg / L or less and / or the 90% particle size of the suspended solids 100 μm or less. Preferably, the suspension is roughly separated by a rough solid-liquid separation operation such as centrifugation or standing. Although there is no particular lower limit of turbidity, these rough solid-liquid separation operations are unlikely to be below about 100 mg / L. When the crude sodium silicate solution in a suspended state before the solid-liquid separation operation is maintained at 60 to 100 ° C., the viscosity of the solution can be lowered, and the separability of the suspended substance is increased.

The features of the present invention are as follows.
(1) As a by-product of the silicon purity improvement process, a sodium-based by-product containing silicon and containing sodium silicate as a main component is dissolved in water, and the silicon is dissolved to generate hydrogen gas. A method for producing a sodium silicate solution, comprising producing a sodium silicate solution.

  (2) The sodium-based byproduct is charged into water, and sodium silicate in the sodium-based byproduct is dissolved in water to form a sodium silicate solution, and silicon in the sodium-based byproduct Is generated by decomposing the sodium-based by-product by generating hydrogen gas from the interface of the silicon, thereby separating silicon in the sodium-based by-product and attaching the hydrogen gas to the surface of the separated silicon. The method for producing a sodium silicate solution according to (1), wherein the sodium silicate solution is produced by levitating the silicon onto the water by buoyancy and removing the floated silicon.

(3) In the sodium silicate solution after the silicon is levitated and removed, the undissolved sodium silicate is separated and recovered, and the separated and recovered sodium silicate is dissolved in water to further produce a sodium silicate solution. (2) The method for producing sodium silicate according to (2).
(4) The silicon removed by the floating separation is recovered, the recovered silicon is charged into the sodium silicate solution in a fixed amount, and the charged silicon is dissolved in the sodium silicate solution, so that the SiO in the solution is dissolved. _The method for producing a sodium silicate solution according to (2) or (3), wherein the ₂ / Na ₂ O molar ratio is adjusted.
(5) The method for producing a sodium silicate solution according to (4), wherein the silicon for adjusting the molar ratio is dissolved in a sodium silicate solution at 60 to 100 ° C. under atmospheric pressure.

( 6 ) After heating and melting metal silicon containing boron as an impurity, the sodium-based by-product is a solid mainly composed of silicon dioxide, and one of sodium carbonate or sodium carbonate hydrated salt. Or, a solid mainly composed of both is added to the molten silicon to form a slag mainly composed of sodium silicate, and boron in the molten silicon is moved to the slag and removed from the silicon. The method for producing a sodium silicate solution according to any one of (1) to ( 5 ), which is a sodium-based byproduct made of the slag, which is by-produced in the boron removal method.

( 7 ) The sodium-based by-product is added to any one of sodium oxide, hydroxide, carbonate, fluoride, or two or more of these compounds to a SiO solid to form a mixture, Any one of (1) to ( 5 ), wherein the mixture is a sodium-based byproduct that is by-produced in a method for producing Si by heating Si to a melting point of Si or higher. The manufacturing method of the sodium silicate solution as described in 2.

( 8 ) The silicic acid according to any one of (1) to ( 7 ), wherein the sodium-based by-product is dissolved in water at 60 to 100 ° C. under atmospheric pressure. Method for producing sodium solution.

( 9 ) When the sodium-based by-product or the separated slag is dissolved in water, the sodium-based by-product is dissolved under a pressure exceeding atmospheric pressure, according to any one of (1) to ( 7 ) A method for producing a sodium silicate solution.

( 10 ) When dissolving the sodium-based by-product in water, dissolving it under atmospheric pressure to generate hydrogen gas, and further dissolving the sodium-based by-product under a pressure exceeding atmospheric pressure (1)-( 7 ) The manufacturing method of the water glass as described in any one of ( 7 ) characterized by these.

( 11 ) The sodium silicate solution produced by the method according to any one of (1) to ( 10 ) is mixed with at least one of a sodium compound, sodium silicate, and soluble silica, and SiO ₂ / Na in the solution is mixed. _A method for producing a sodium silicate solution, comprising producing a sodium silicate solution having an adjusted ₂ O molar ratio.

(1 2) the sodium compound, wherein the sodium silicate, at least one of the soluble silica, in the form of solid or aqueous solution, characterized by mixing the sodium silicate solution (11) production of sodium silicate solution according Method.

(1 3 ) By applying one or more methods of centrifugation and standing to the sodium silicate solution produced by the method according to any one of (1) to (1 2 ), A method for producing a sodium silicate solution, characterized by separating turbid substances.

  (14) The sodium silicate solution produced in (1) to (13) is any of a ground improver, a binder for molding, a deinking agent for waste paper, and a stabilizer for hydrogen peroxide when straying paper and pulp. Or a method of using a sodium silicate solution, characterized by being used as a substitute for one drug.

According to the present invention, it is possible to recycle a by-product (sodium-based byproduct) containing silicon and containing sodium silicate as a main component by-product from the silicon purity improving process. , Suppresses component fluctuations such as the molar ratio of sodium silicate solution (SiO ₂ / Na ₂ O) and suspended solids concentration, and solves safety problems due to the generation of hydrogen gas derived from silicon contained in by-products This makes it possible to produce a sodium silicate solution.

  Moreover, the manufactured sodium silicate solution can be used as a chemical substitute for any one of a ground conditioner, a caking agent at the time of mold making, a deinking agent for waste paper, and a stabilizer for hydrogen peroxide when straying paper and pulp. .

  First, the whole structure (FIGS. 1-3) which manufactures a sodium silicate solution from the sodium-based by-product containing silicon is demonstrated.

As shown in FIG. 1, the sodium-based by-product is preferably crushed, and then the sodium-based by-product is dissolved to create a sodium silicate solution. It can be used as a substitute for any one of the agent and the stabilizer of hydrogen peroxide when paper and pulp are drifting. More preferably, as shown in FIG. 2, the sodium-based by-product is preferably crushed, the sodium-based by-product is dissolved to prepare a sodium silicate solution, and then the molar ratio (SiO ₂ / Na ₂ O) is changed. By adjusting, the component composition becomes stable, and it becomes easier to use as a medicine substitute. Furthermore, by separating in advance the silicon in the slag having a large variation in the content before preparing the sodium silicate solution, the component composition of the sodium silicate solution is more stable and easier to use as a chemical substitute. Specifically, as shown in FIG. 3, after crushing the sodium-based byproduct, it is put into a decomposition / flotation separation / dissolution apparatus to separate the sodium-based byproduct into a silicon component and a slag component, The silicon content is levitated in the same tank and separated from the slag content. The separated slag is dissolved in the same tank to prepare a crude sodium silicate solution containing suspended substances. The surfacing silicon is collected by the levitated material collecting device. The molar ratio (SiO ₂ / Na ₂ O) in the crude sodium silicate solution containing the suspended substance is adjusted, and then the suspended substance is separated from the crude sodium silicate solution containing the suspended substance by solid-liquid separation operation. A sodium silicate solution is obtained.

  In addition, metal silicon concentration measurement, when sodium by-product is put in an alkaline solution (sodium hydroxide solution), hydrogen gas is generated if silicon is contained. The amount of hydrogen gas can be calculated from the hydrogen concentration in the gas, and can be calculated from the amount of hydrogen gas based on (Equation 4).

^{Si (s) + 2OH - +} H 2 O → SiO 3 2- + 2H 2 (g) ↑ ---- ( Equation 4)
In FIG. 2 to FIG. 3, the molar ratio (SiO ₂ / Na ₂ O) adjustment is described to be performed after slag dissolution, but may be performed before slag dissolution and before suspended substance separation. Specifically, at least one of a sodium compound, sodium silicate, and soluble silica is mixed with the manufactured sodium silicate solution, and the SiO ₂ / Na ₂ O molar ratio in the mixed solution is adjusted. The soluble silica is an alkali-soluble silica that can be used for adjusting the molar ratio, but is preferably amorphous silica such as white carbon, silica gel, diatomaceous earth, and the like. When crystalline silica such as cinnabar is used, it can be used if it is pulverized.

  Next, the best mode for each apparatus will be described based on the respective equipment flows shown in FIGS.

1) Crusher The sodium-based by-product in which silicon is mixed preferably has a maximum diameter after crushing of 1 mm to 50 mm in order to more effectively perform the collapse described later and the rising of the collapsed silicon. If it is less than 1 mm, it may take too much time and labor to grind the sodium-based by-product. If it exceeds 50 mm, it may not sufficiently float or rise even if it collapses. Furthermore, a preferable maximum diameter is 5 mm to 20 mm.

  Furthermore, as shown in FIG. 3, when the sodium-based by-product is decomposed into silicon and slag in the same tank and silicon is levitated, the silicon becomes an underlay of the slag and is difficult to levitate later. It is important that the maximum diameter of the sodium-based by-product after crushing is 5 mm to 10 mm along with the kneading of the lower part of the tank so that the silicon can easily float.

2) Slag melting tank An example of the equipment configuration of the slag melting apparatus used for “slag melting” described in FIGS. 1 and 2 will be described with reference to FIG.

  The “slag dissolving device” includes a slag dissolving tank 81 into which sodium-based by-product or slag 83 and water 84 are charged, a stirrer 82 for stirring the slag dissolving tank 81, and steam for adjusting the water temperature in the slag dissolving tank 81. 87, a regulating valve 88 and a thermometer 89, a water level meter 85 for measuring the water level in the slag dissolving tank 81, a hydrometer 86 for measuring the liquid specific gravity in the slag dissolving tank 81, and temporarily at the bottom of the slag dissolving tank 81 A slag interface meter 91 for detecting the accumulation state of sodium-based by-products or slag 83 deposited on the slag, and a pump for feeding the crude sodium silicate solution prepared in the slag dissolution tank 81 to the suspended substance separator 90.

  Water 84 is introduced into the slag dissolution tank 81, and the water level in the slag dissolution tank 81 is kept constant by a water level meter 85. Next, the water temperature is controlled within a range of 60 to 100 ° C. by the steam 87 and the thermometer 89, and the inside of the tank is slowly stirred by the stirrer 82. Next, the sodium-based by-product or slag 83 is charged to a predetermined height with the slag interface meter 91 and is dissolved in the slag dissolution tank 81. Although the liquid specific gravity in the slag dissolution tank 81 is dissolved by the hydrometer 86 until it becomes 1.3 to 2.0, it takes 3 to 12 hours to dissolve the sodium-based by-product or the slag 83. The crude sodium silicate solution whose liquid specific gravity is adjusted to 1.3 to 2.0 is sent to the next suspended substance separation device by the pump 90. After the liquid feeding, the water level is lowered, so water 84 is introduced and the liquid specific gravity is lowered. The sodium-based by-product or slag 83 in the lower part of the slag dissolution tank 81 is dissolved, the slag interface is lowered, and the sodium-based by-product or slag 83 is charged to continuously produce a crude sodium silicate solution.

  Although the method for dissolving sodium-based by-products or slag by semi-continuous operation has been described, it can also be dissolved by batch operation.

  In addition, the slag can be dissolved under a pressure exceeding atmospheric pressure. In this case, an autoclave and a simple pressure cooker can be used.

  In order to dissolve the sodium-based by-product, after dissolving under atmospheric pressure to generate hydrogen gas, the sodium-based by-product can be further dissolved under a pressure exceeding atmospheric pressure. The dissolution of the sodium silicate component has the advantage that it is faster under atmospheric pressure than under atmospheric pressure.

3) Decomposition / Flotation Separation / Dissolution Device The decomposition / flotation separation / dissolution device used in “Decomposition / Silicon / Slag Separation / Slag Melting” in FIG. 3 decomposes sodium-based by-products into silicon and slag parts. In addition, the decomposed silicon portion is levitated and slag is dissolved in the same tank to prepare a crude sodium silicate solution containing suspended substances.

  A detailed view of the process flow decomposition, silicon / slag separation, and slag melting portion of FIG. 3 is shown in FIG. 5 and will be described using the decomposition / flotation separation device therein.

  The "decomposition / flotation separation / dissolution apparatus" is a decomposition / flotation separation / dissolution tank 62 that disintegrates the sodium-based by-product crushed by the crusher and floats silicon, and a decomposition / flotation separation / dissolution tank. Steam 69 that raises the temperature of water (alkaline) in 62, a thermometer 68 that measures the temperature of the water, a regulating valve 70 that adjusts the input amount of steam 69, and the decomposition / flotation separation / dissolution tank 62 The pH meter 67 for measuring the pH of the liquid, the hydrometer 65 for measuring the liquid specific gravity in the decomposition / flotation separation / dissolution tank 62, and the disintegration in the decomposition / flotation separation / dissolution tank 62, and sinking to the bottom. It comprises a kneading device 71 for kneading the slag 75 and the silicon 64. The slag portion 75 is dissolved in the decomposition / flotation separation / dissolution tank 62 to become a crude sodium silicate solution containing suspended solids, and a pump 77 for feeding the crude sodium silicate solution to the suspended solid separation device. It consists of.

  The sodium-based by-product crushed by the crusher is received by the receiving hopper 1 and then quantitatively cut out from the cutting device 2. The amount of cut out is determined by the amount of hydrogen gas (explosion limit concentration lower limit 4%, upper limit 74.2%) generated in the “decomposition / flotation separation / dissolution device” and the exhaust system used as a countermeasure for hydrogen gas (Fig. 4). (Not shown in the figure) is preferably determined. From the viewpoint of suppressing fluctuations in the generation of hydrogen gas, a quantitative cutout is preferable for safety.

  The sodium-based by-product introduced into the decomposition / flotation separation / dissolution tank 62 from the supply device 3 reacts with water at the interface of the silicon portion in the decomposition / flotation separation / dissolution tank 62 to generate hydrogen gas. This causes the sodium-based by-products to collapse, a hydrogen gas layer is formed on the silicon surface, and the silicon that is not underlying the slag rises. In addition, since the amount of hydrogen gas generated on the silicon surface is intense, the change in the thickness of the hydrogen gas layer on the silicon surface is significant, so that the smaller the silicon particle diameter, the easier it is to float. Although it depends on the size of silicon, about 60 to 90% of silicon floats if it is 5 mm or less.

  The slag portion 75 separated from the sodium-based by-product is separated and the underlying silicon portion 64 are intermittently and slowly kneaded by the kneading device 71 at the bottom of the decomposition / flotation separation / dissolution tank, The slag portion 75 is given an opportunity to float on the underlying silicon 64, and the decomposition / flotation separation / dissolution tank 62 is slowly mixed. For example, when a screw conveyor is used as the kneading device 71, by allowing the screw to rotate in the forward and reverse directions, the silicon is given a chance to float, and the inside of the decomposition / flotation separation / dissolution tank 62 is provided. Mix slowly.

  The slag portion 75 is dissolved in water in the decomposition / flotation separation / dissolution tank 62 over about 3 to 12 hours to become a crude sodium silicate solution containing suspended solids. The liquid specific gravity of the sodium silicate solution is adjusted within the range of 1.3 to 2.0 with the hydrometer 65, and after confirming that the specific gravity has reached a predetermined value, the crude sodium silicate containing suspended solids is pumped by the pump 77. The solution is sent to the suspended material separator. When a screw conveyor is used as the kneading device 71, the unreacted residue 78 can be carried into the unreacted residue pit 76.

  Silicon floats to the upper part of the decomposition / flotation separation / dissolution tank 62, and is scraped by the floated material scraping device 63 and supplied to the floated material collecting device described later.

4) Floating matter recovery apparatus Silicon floated by the decomposition / flotation separation / dissolution apparatus shown in FIG. 3 is introduced into the floating substance recovery apparatus by a scraping device together with an alkaline aqueous solution. In the levitated material recovery apparatus, silicon is separated from the alkaline aqueous solution.

  One example of the equipment configuration of the “floating object recovery device” will be described using the floating object recovery device (22 to 24) in FIG. The “floating material recovery device” includes a filter 24 that receives the floating silicon 64 raked by the floating material scraping device 63 and filters and recovers silicon, and a temporary storage tank 23 that temporarily stores the crude sodium silicate solution separated from the filter. And a recovery pump 22 that returns the crude sodium silicate solution in the temporary storage tank 23 to the decomposition / flotation / dissolution tank 62.

  Due to the hydrogen gas layer formed on the silicon surface, the silicon 64 floats to the upper part of the decomposition / flotation / dissolution tank 62 and is scraped by the floated material scraping device 63, and the silicon 64 together with a small amount of the crude sodium silicate solution is filtered. 24. In the filter 24, a filtration machine such as a centrifugal separator or a membrane can be used, but can be sufficiently recovered by separation with a sieve. As the sieve mesh, an opening of 40 μm to 2 mm is appropriate. If it is smaller than 40 μm, clogging may occur. If it is larger than 2 mm, the silicon recovery efficiency may be extremely deteriorated. The silicon 64 collected in the filter 24 has a high purity of 90% or more as silicon, and can be used as a deoxidizing material used in the steel industry. Further, depending on the components of impurities other than silicon, it can be sufficiently recycled as a silicon raw material. The crude sodium silicate solution separated by the filter 24 is temporarily stored in the temporary storage tank 23 and returned to the decomposition / flotation / dissolution tank 62 by the recovery pump 22.

5) Molar ratio adjusting device In the molar ratio (SiO ₂ / Na ₂ O) adjustment shown in FIGS. 1 to 3, the slag dissolution shown in FIG. 1 or 2 or the decomposition / flotation separation / dissolution device shown in FIG. The molar ratio (SiO ₂ / Na ₂ O) is adjusted by adding at least one of a sodium compound, sodium silicate, and soluble silica to the crude sodium silicate solution and dissolving or mixing them.

In the molar ratio (SiO ₂ / Na ₂ O) adjustment of FIG. 3, in addition to the above-described method, the molar ratio (SiO Silicon which is the main factor that fluctuates ₂ / Na ₂ O) can be uniformly mixed, and fluctuations in the molar ratio of the crude sodium silicate solution (SiO ₂ / Na ₂ O) can be suppressed. When silicon is mixed with the crude sodium silicate solution and reacted, hydrogen gas is generated. Therefore, an open-type mixing tank is suitable, and the water temperature is preferably 60 to 100 ° C. at which metallic silicon easily reacts.

6) Suspended substance separator In the suspended substance separator, the suspended substance is separated from the crude sodium silicate solution containing the suspended substance prepared by the decomposition / flotation separation / dissolution apparatus in FIG.

  In order to separate suspended substances, there are methods such as centrifugation and standing. By these methods, coarse particles can be separated and suspended substances can be separated. Although the separable particle size varies depending on the separation method, suspended substances of 5 to 100 μm or more can be separated by centrifugation, and 20 to 100 μm or more can be separated by standing for several days. Turbidity can be suppressed to 5000 mg / L or less.

  When a crude sodium silicate solution containing a suspended substance is allowed to stand at room temperature for several days, it aggregates and spontaneously settles. At this time, a substance considered to be zeolite is also precipitated, which increases the particle diameter due to crystal growth, and also becomes a floc due to the agglomeration effect, and is likely to settle.

  Sodium silicate solution from which suspended solids have been separated can be used as a chemical replacement for any one of ground improvement agents, binders used in mold making, deinking used paper, and hydrogen peroxide stabilizers used in paper and pulp drifting. Can be used.

  Further, the separated suspended substance has a sufficient solidifying action because it contains a large amount of sodium silicate solution together with unreacted substances. Therefore, when it is naturally dried, it becomes slag and can be discarded.

  In FIG. 5, the floated silicon is described as being separated by a scraper (63). However, a separately prepared crude sodium silicate solution is put into the tank (62), and the water level of the tank (62) is temporarily set. The silicon can be recovered by causing the floating silicon to overflow to the “floating object recovery device” installed outside the tank system.

  A beaker containing 200 ml of pure water was charged with 100 g of a sodium-based byproduct from the boron removal method, and the pH was maintained at a predetermined value with an aqueous solution of sodium hydroxide or hydrochloric acid (alkaline aqueous solution (a)). Two minutes later, a sodium-based by-product was taken out and examined for its decay state. Table 1 shows the pH and temperature of the alkaline aqueous solution (a) and the results (disintegration status of sodium-based byproducts). The disintegration state was determined by separating the sodium-based by-product that was input into one that was not disintegrated and one that was not disintegrated, and examining the ratio (%) of the disintegrated mass to the total mass input. In addition, when not adjusting pH, pH12.3 was shown.

  In the alkaline aqueous solution (a) having a pH of 8 or more, as shown in Examples a-3 to a-12 in Table 1, hydrogen was generated from the silicon interface and the surface, and the sodium-based by-product collapsed. On the other hand, in the comparative examples a-1 to a-2 in Table 1, when the pH was less than 8, there was almost no generation of hydrogen gas, and the sodium-based byproduct did not collapse.

  Furthermore, using the sodium-based by-product disintegrated in Table 6 a-6, sodium disintegrated in a beaker containing 200 ml of an aqueous alkaline solution (b) maintained at a predetermined value with aqueous sodium hydroxide or hydrochloric acid. The system by-product was added and allowed to stand for 1 minute, and then the silicon floating state was examined. The specific gravity of the alkaline aqueous solution (b) was prepared by further adding water glass. Table 2 shows the pH, temperature, and liquid specific gravity of the alkaline aqueous solution (b), and the results (the floating state of silicon). As for the floating condition, the ratio (%) of the mass of silicon that had floated to the silicon content (mass) in the input amount of the sodium-based by-product was examined.

  In the alkaline aqueous solution (b) having a pH exceeding 8, the collapsed sodium-based by-product has bubbles generated by hydrogen generation on the silicon surface as shown in the examples b-3 to b-12 in Table 2, Surfaced selectively. On the other hand, as shown in the comparative examples b-1 to b-2 in Table 2, when the pH was 7 or less, there was almost no generation of hydrogen gas and silicon did not float.

As described above, the following can be said from the results shown in Tables 1 and 2.
(1) In order to disintegrate the sodium-based by-product, the pH is preferably 8 or more and the water temperature is preferably 60 ° C. or more. (When a sodium-based by-product is dissolved in water, the pH becomes 12 to 13, so pH adjustment is not necessary.)

(2) Disintegrating silicon-based by-products and separating silicon will surface if the pH is 8 or more. However, when the water temperature is high, particularly when the water temperature is 60 ° C. or higher, the amount of hydrogen generated from silicon is large, and it is necessary to quickly separate silicon from the alkaline solution.

The sodium-based by-product from the boron removal method was crushed to under 20 mm and used as a sample. The main components of the slag in the sodium-based byproduct are Na ₂ O: 32.8% by mass and SiO ₂ : 64.9% by mass, and the silicon content in the sodium-based byproduct is 2.1% by mass. It is. The total of CaO, Al ₂ O ₃ and MgO is 0.04%. 600 g of this sodium-based by-product and 1200 g of water were placed in a stainless steel open container and stirred while heating to 80 ° C. to obtain a sodium silicate solution. At the time of melting, hydrogen gas was generated from silicon, but it was a melting operation in an open state and in a drafter, and no problem occurred in terms of safety.

The obtained sodium silicate solution was Na ₂ O: 11.9% by mass, SiO ₂ : 25.3% by mass, molar ratio: 2.19, and turbidity: 3800 mg / L.

  50 g of white carbon was mixed with 500 g of the sodium silicate solution obtained in Example 2, and the white carbon was dissolved at 80 ° C. to obtain a sodium silicate solution.

The obtained sodium silicate solution has Na ₂ O: 10.3 mass%, SiO ₂ : 31.3 mass%, molar ratio: 3.1, and turbidity: 3600 mg / L. It was possible.

The sodium-based by-product from the SiO method was crushed to 20 mm and used as a sample, and was carried out with the apparatus of FIG. The capacity of the decomposition / flotation / dissolution tank 62 is 300L. The main components of the slag portion in the sodium-based byproduct are Na ₂ O: 32.7% by mass and SiO ₂ : 64.8% by mass, and the silicon content in the sodium-based byproduct is 2.1% by mass. % (Changes from 1 to 5%).

  First, 150 kg of sodium-based byproduct is charged into the decomposition / flotation / dissolution tank 62 of FIG. 5 and the temperature in the tank is maintained at 95 ° C. for about 10 hours by steaming, so that the sodium-based byproduct is almost dissolved. An alkaline aqueous solution (d) was prepared. The alkaline aqueous solution (d) in the decomposition / flotation / dissolution tank 62 had a pH of 12 to 12.5 and a liquid specific gravity of 1.4. After adjusting the temperature of the decomposition / flotation / dissolution tank 62 to 90 ° C., the sodium-based by-product is continuously quantitatively cut out (1 kg / min) from the cutting device 2 and the liquid specific gravity becomes 1.4. While adding water, 2100 kg of the sodium-based by-product was further treated, and the floating silicon was separated and recovered.

  Further, the slag 75 stayed at the bottom of the decomposition / flotation / dissolution tank 62, and the slag 75 was dissolved by rotating the screw conveyor 71 forward and backward for 10 seconds every 30 seconds. The crude sodium silicate solution containing the generated suspended substance was fed to the molar ratio adjustment step by a pump 77. The unreacted residue 76 remaining as an unreacted residue in the decomposition / flotation / dissolution tank 62 was carried into the unreacted residue pit 76 by rotating the screw conveyor 71 forward after the end of the experiment (10.5 kg). The recovered amount of silicon recovered by the filter 24 was 0.25 kg / min.

  The purity of the recovered silicon was 98.0%, and the remaining components were sodium silicate components. Therefore, the recovered silicon was of a quality that can be recycled as a deoxidizer used in the refining process, which is a steel manufacturing process. Furthermore, it was also a quality that can be recycled as a silicon raw material used in the silicon purity improvement process. During the dissolution of the sodium-based by-product, there was no problem for safety because the exhaust system was exhausted.

In the molar ratio adjusting step, the obtained crude sodium silicate solution was adjusted in molar ratio by 50 kg. Specifically, 5 kg of white carbon was introduced per 50 kg and dissolved at 80 ° C. for 5 hours to adjust the molar ratio (SiO ₂ / Na ₂ O). Thereafter, the suspended substance was roughly separated with a centrifugal separator to obtain a sodium silicate solution. Table 3 shows the components of the crude sodium silicate solution and the sodium silicate solution in Example 4, but the chemical replacement of the ground improvement agent was possible.

  Further, as Example 4 ', Table 3 shows the components of the crude sodium silicate solution and the sodium silicate solution when silicon is not separated in the decomposition / flotation / dissolution tank.

As shown in Table 3, in Example 4 and Example 4 ′, the stability of the molar ratio of the sodium silicate solution that can be produced (SiO ₂ / Na ₂ O) is different, and Example 4 is more stable. Compared to Example 4 ′, it is less subject to application restrictions.

The sodium-based by-product from the SiO method was crushed to 20 mm and used as a sample, and was carried out with the apparatus of FIG. The capacity of the decomposition / flotation / dissolution tank 62 is 300L. The main components of the slag portion in the sodium-based byproduct are Na ₂ O: 32.7% by mass and SiO ₂ : 64.8% by mass, and the silicon content in the sodium-based byproduct is 2.1% by mass. % (Changes from 1 to 5%).

  First, 150 kg of sodium-based byproduct is charged into the decomposition / flotation / dissolution tank 62 of FIG. 5 and the temperature in the tank is maintained at 95 ° C. for about 10 hours by steaming, so that the sodium-based byproduct is almost dissolved. An alkaline aqueous solution (d) was prepared. The alkaline aqueous solution (d) in the decomposition / flotation / dissolution tank 62 had a pH of 12 to 12.5 and a liquid specific gravity of 1.4. After adjusting the temperature of the decomposition / flotation / dissolution tank 62 to 90 ° C., the sodium-based by-product is continuously quantitatively cut out (1 kg / min) from the cutting device 2 and the liquid specific gravity becomes 1.4. While adding water, 2100 kg of the sodium-based by-product was further treated, and the floating silicon was separated and recovered.

  Further, the slag 75 stayed at the bottom of the decomposition / flotation / dissolution tank 62, and the slag 75 was dissolved by rotating the screw conveyor 71 forward and backward for 10 seconds every 30 seconds. The crude sodium silicate solution containing the generated suspended substance was sent to the molar ratio adjusting step by a pump 77. The unreacted residue 76 remaining as an unreacted residue in the decomposition / flotation / dissolution tank 62 was carried into the unreacted residue pit 76 by rotating the screw conveyor 71 forward after the end of the experiment (10.5 kg). The recovered amount of silicon recovered by the filter 24 was 0.25 kg / min. During the dissolution of the sodium-based by-product, there was no problem for safety because the exhaust system was exhausted.

  In the molar ratio adjusting step, 0.6 kg of silicon recovered per 50 kg was mixed with the obtained crude sodium silicate solution, and 4 kg of white carbon was added and dissolved at 80 ° C. for 5 hr to adjust the molar ratio. Thereafter, the suspended substance was roughly separated to obtain a sodium silicate solution. Table 2 shows the components of the crude sodium silicate solution and the sodium silicate solution in Example 5. During the melting of the silicon, there was no problem for safety because the exhaust system exhausted the silicon.

  From Table 3, it can be said that a sodium silicate solution having a small fluctuation range of the molar ratio can be obtained.

1st Embodiment of the process flow in the manufacturing method of the sodium silicate solution of this invention is shown. (No separation of silicon and suspended matter) 2nd Embodiment of the process flow in the manufacturing method of the sodium silicate solution of this invention is shown. (Molar ratio adjustment available) 3rd Embodiment of the process flow in the manufacturing method of the sodium silicate solution of this invention is shown. (Decomposition / flotation / dissolution / suspension substance separation / molar ratio adjustment) The slag melt | dissolution equipment used for the slag melt | dissolution in 1st or 2nd embodiment and 2nd Embodiment is shown. The detailed equipment of decomposition | disassembly, silicon | silicone / slag isolation | separation, and slag melt | dissolution in 3rd Embodiment is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Accepting hopper 2 Cutting device 3 Feeding device 22 Recovery pump 23 Temporary storage tank 24 Filter 62 Disassembly / flotation / dissolution tank 63 Floating substance scraping device 64 Silicon 65 Hydrometer 67 pH meter 68 Thermometer 69 Steam 70 Adjustment valve 71 Kneading device 75 Slag 76 Unreacted residue pit 77 Pump 78 Unreacted residue 81 Slag dissolving tank 82 Stirrer 83 Slag 84 Water 85 Water level meter 86 Hydrometer 87 Steam 88 Adjusting valve 89 Thermometer 90 Pump 91 Slag interface meter

Claims (14)

  A by-product of the silicon purity improving process, containing a silicon-based by-product containing silicon and containing sodium silicate as a main component is dissolved in water to dissolve the silicon and generate hydrogen gas. The manufacturing method of the sodium silicate solution characterized by manufacturing a solution.   The sodium-based by-product is charged into water, sodium silicate in the sodium-based by-product is dissolved in water to form a sodium silicate solution, and from the silicon interface in the sodium-based by-product. By generating hydrogen gas and collapsing the sodium-based byproduct, the silicon in the sodium-based byproduct is separated, and the buoyancy generated by the adhesion of the hydrogen gas to the surface of the separated silicon, The method for producing a sodium silicate solution according to claim 1, wherein the silicon silicate solution is produced by levitating the silicon on water and removing the floated silicon.   Separating and recovering undissolved remaining sodium silicate in the sodium silicate solution after the silicon has been levitated and removed, dissolving the separated and recovered sodium silicate in water, and further producing a sodium silicate solution. The method for producing sodium silicate according to claim 2, characterized in that: The silicon removed by the flotation separation is recovered, the recovered silicon is added to the sodium silicate solution in a certain amount, and the injected silicon is dissolved in the sodium silicate solution, so that the SiO in the solution is dissolved. ₂ / Na ₂ The method for producing a sodium silicate solution according to claim 2 or 3, wherein an O molar ratio is adjusted. 5. The method for producing a sodium silicate solution according to claim 4, wherein when the silicon for adjusting the molar ratio is dissolved in the sodium silicate solution, the silicon silicate solution is dissolved at 60 to 100 ° C. under atmospheric pressure. The sodium-based by-product is obtained by heating and melting metal silicon containing boron as an impurity, and then adding a solid mainly composed of silicon dioxide and one or both of sodium carbonate and sodium carbonate hydrate. Boron removal from silicon that adds solids as a main component to the molten silicon to form a slag mainly composed of sodium silicate and removes boron in the molten silicon by moving to the slag The method for producing a sodium silicate solution according to any one of claims 1 to 5 , wherein the sodium silicate byproduct is formed as a by-product of the slag. The sodium-based by-product is added to any one of sodium oxide, hydroxide, carbonate, fluoride, or two or more of these compounds to a SiO solid to form a mixture. The sodium silicate according to any one of claims 1 to 5 , wherein the sodium silicate is a sodium-based byproduct produced as a by-product in a method for producing Si by heating to a melting point of Si or higher. A method for producing a solution. The method for producing a sodium silicate solution according to any one of claims 1 to 7 , wherein when dissolving the sodium-based by-product in water, the sodium-based by-product is dissolved in water at 60 to 100 ° C under atmospheric pressure. . The sodium silicate solution according to any one of claims 1 to 7 , wherein the sodium-based by-product or the separated slag is dissolved in water at a pressure exceeding atmospheric pressure. Method. When the sodium-based by-product is dissolved in water, after dissolving under atmospheric pressure to generate hydrogen gas, the sodium-based by-product is further dissolved under a pressure exceeding atmospheric pressure, method for producing a sodium silicate solution according to any one of claims 1 to 7. The sodium silicate solution prepared by the method according to any one of claims 1-10, sodium compound, sodium silicate, a mixture of at least one soluble silica, the SiO ₂ / Na ₂ O molar ratio in the solution A method for producing a sodium silicate solution, comprising producing an adjusted sodium silicate solution. The method for producing a sodium silicate solution according to claim 11 , wherein at least one of the sodium compound, the sodium silicate, and the soluble silica is mixed with the sodium silicate solution in a solid or aqueous solution state. Separating suspended solids by subjecting the sodium silicate solution produced by the method according to any one of claims 1 to 12 to one or more of centrifugation and standing. The manufacturing method of the sodium silicate solution characterized by these.   The sodium silicate solution produced in any one of claims 1 to 13 is replaced with any one of a ground improver, a binder for molding, a deinking agent for used paper, and a stabilizer for hydrogen peroxide when floating on paper and pulp. A method of using a sodium silicate solution, characterized by being used as:

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