RU2220906C1 - Liquid glass manufacture process - Google Patents

Abstract

FIELD: glassmaking. SUBSTANCE: invention relates to technology of manufacturing liquid glass with different silica modulus applicable in soap, fat, and chemical industries, mechanical engineering, textile industry, papermaking, construction, metallurgy, and other areas. Liquid glass is prepared via interaction of silica-containing substance with sodium hydroxide aqueous solution at 200-250 C, said silica-containing substance being used fractioned quartz sand fraction 0.1-0.315 mm containing 95.5- 98.15% silica, 0.05-0.13% calcium oxide, 0.1-1.5% water, and 1.7-2.83% other metal oxides. Interaction is chiefly carried out at weight ratio of initial quartz sand to sodium hydroxide (calculated for silicon oxide and sodium oxide) equal to (2.2-3.6): 1. EFFECT: allowed use of accessible raw material and simplified technology due to excluded power-consuming preliminary grinding stage.

Description

 The invention relates to a technology for producing solutions of sodium silicate (water glass) with various silicate modules used in soap, fat, chemical, engineering, textile and paper industries, as well as in the construction industry, metallurgy and for other purposes.

A known method of producing liquid glass, including the preparation of a suspension of silica-containing amorphous material with a particle size (80-200 or more) • 10 ^-6 m, which is a waste product of crystalline silicon, in sodium hydroxide solution in the ratio of solid and liquid phases in suspension T: W = 1: (1.9-5.65) followed by hydrothermal treatment of the suspension at 0.3 MPa and 130-150 ^o C for 35-240 minutes [Patent 2171223 of the Russian Federation, July 27, 2001. IPC ⁷ C 01 B 33/32].

 The disadvantage of this method is the use of relatively scarce raw materials - waste production of crystalline silicon.

 A known method of producing liquid glass by the interaction of ground quartz sand and aqueous solutions of potassium or sodium hydroxide at elevated temperatures and pressure in an autoclave [Application 3515233 Germany, 1986. IPC 01 B 33/32]. As the initial quartz sand in this method, sand is used, grinding of which is carried out in a ball mill in the presence of a 50% solution of alkali metal hydroxide with the addition of water, the grinding time of sand is 3-48 hours, preferably up to 24 hours.

 The disadvantages of this method are the need for grinding the initial silica-containing substance in the presence of alkali and the related complexity of the production technology.

The closest in technical essence and the achieved result to the proposed method is a method for producing liquid glass, comprising mixing and subsequent interaction of a silica-containing substance, which is pre-crushed to a specific surface of 2000-20000 cm ² / g, with an aqueous solution of alkali metal hydroxide at a temperature of 100-250 ^o With and the vapor pressure arising at this temperature [Patent 2078433 of the Russian Federation, 04/27/1997. IPC ⁶ C 01 B 33/32].

The disadvantages of this method are the need for preliminary grinding of a silica-containing substance (sand) to a specific surface in the range of 2000-20000 cm ² / g and the associated relatively high energy costs.

 The objective of the proposed method is to simplify the technology for producing liquid glass by eliminating from the process the stage of preliminary grinding of a silica-containing substance (sand) and reducing energy costs for the production of the product.

This is achieved by the fact that in the process of producing liquid glass by the interaction of a silica-containing substance with aqueous solutions of sodium hydroxide at a temperature in the range of 200-250 ^o C and the pressure arising at this temperature, fractionated silica sand of a fraction of 0.1-0.315 mm is used as the initial silica-containing substance, containing 95.5-99.0 wt.% silicon dioxide, 0.05-0.13 wt.% calcium oxide, 0.1-1.5 water and from 1.7 to 2.83 wt.% oxides of other metals .

The method is carried out mainly with a mass ratio of the original quartz sand and sodium hydroxide in terms of silicon dioxide and sodium oxide in the range of SiO ₂ : Na ₂ O = 2.2-3.6: 1.

 The set of essential features, including the use of a finely dispersed fraction (0.1-0.315 mm) of fractionated quartz sand of the specified composition, leads to the achievement of the expected technical result - simplification of the technology for producing liquid glass by eliminating the stage of preliminary grinding of sand and reducing energy costs associated with it.

 The use of quartz sand with a particle size of more than 0.315 mm in the process, as well as sand with a silica content of less than 95.5 wt. % and / or a calcium oxide content of more than 0.13%, is technically and economically impractical, since it significantly increases the duration of the process and energy consumption or causes a decrease in the yield and quality of the target product.

 Implementation of the proposed method with the indicated mass ratios of quartz sand and sodium hydroxide provides sodium liquid glass with a silicate module in the range of 2.3-3.6 and other technical indicators that fully comply with the requirements of GOST 13078-81 "Sodium liquid glass" for various grades. With different mass ratios of reagents according to the proposed method, sodium silicate solutions with a silicate module are obtained that go beyond the standards of the specified GOST, although they are used in some industries.

 The following are examples illustrating the proposed method. In all examples, fractionated quartz sand of a fraction of 0.1-0.315 mm containing 95.5-98.15 wt.% Silica, 0.05-0.13 wt.% Calcium oxide, 0.1-1.5 wt. . % water and from 1.7 to 2.83 wt.% oxides of other metals, in the amount of 358.7 g in terms of 100% silicon dioxide.

Example 1 (typical method)
365.5 g of fractionated quartz sand with a particle size in the range 0.1-0.315 mm are placed in a steel autoclave with a working volume of up to 1.5 dm ³ (mass fraction of silicon dioxide 98.15%, mass fraction of calcium oxide 0.05%) , 362.25 g of caustic soda grade RD according to GOST 2263-79 with a mass fraction (ppm) of sodium hydroxide 48.0% and 362.2 g of filtered or demineralized water. The mass ratio of SiO ₂ : Na ₂ O is 3.2: 1. After sealing the autoclave, the reaction mixture is kept under effective stirring at a temperature in the range of 200-250 ^o C and the pressure arising at this temperature. The duration of the process is from 3 to 8 hours. Upon completion of the synthesis, the reaction mixture is cooled to a temperature of 20-60 ^o C, the liquid phase is decanted or unreacted sand is filtered off by known methods. 1084.5 g of liquid sodium glass with a silicate module of 3.21 are obtained. Yield 99.5% of theoretical. The resulting product fully complies with the requirements of GOST 13078-81. Unreacted residue (precipitate) of 5.44 g or 0.5% of the total mass is directly returned to the production cycle for the next operation.

Example 2
The synthesis is carried out according to the method of example 1 based on 366.0 g of silica sand with a ppm of silicon of 98.0%, ppm. calcium oxide 0.1% and ppm water 0.6%, 321.65 g of caustic soda brand RD with ppm sodium hydroxide 48% and 546.15 g of demineralized water. The mass ratio of SiO ₂ : Na ₂ O is 3.6: 1. After synthesis, cooling and unloading of the autoclave, 1222.5 g of water glass with a silicate module of 3.6 and ppm are obtained. silicon dioxide 28.4%, which meets all the requirements of GOST 13078-81. Unreacted residue (precipitate) of 11.3 g or 0.92% of the total mass - directly.

Example 3
The synthesis is carried out according to the method described in example 1, based on 375.6 g of quartz sand with ppm. silica 95.54%, ppm calcium oxide 0.13%, ppm water 1.5%, ppm oxides of other metals 2.83%, 549.2 g of caustic soda brand RD with ppm sodium hydroxide 46.0% and 570.0 g of demineralized water. The mass ratio of SiO ₂ : Na ₂ O is 2.2: 1. After synthesis, cooling and unloading of the autoclave, 1494.6 g of water glass with a silicate module of 2.3 and ppm of silicon dioxide of 23.9% fully complying with the requirements of GOST 13078-81 grade A are obtained. The product yield is quantitative.

As described above, by varying the mass ratio of SiO ₂ : Na ₂ O and the duration of the interaction, liquid glass with a silicate module is obtained in the range 2.0-3.6.

 From the presented examples it follows that the proposed method for the production of liquid glass makes it possible to simplify the technology by eliminating the energy-intensive and prolonged stage of preliminary grinding of silica-containing substance (sand) from the process and thereby significantly reduce the energy costs of producing this product.

Claims (2)

1. The method of producing liquid glass by the interaction of a silica-containing substance with aqueous solutions of sodium hydroxide at a temperature in the range of 200-250 ° C and the overpressure arising at this temperature, characterized in that fractionated silica sand of a fraction of 0.1-0.315 is used as the initial silica-containing substance mm, containing 95.5-98.15 wt.% silicon dioxide, 0.05-0.13 wt.% calcium oxide, 0.1-1.5 wt.% water and from 1.7 to 2.83 wt. .% oxides of other metals. 2. The method according to claim 1, characterized in that the mass ratio of quartz sand and sodium hydroxide in terms of silicon dioxide and sodium oxide is in the range of SiO ₂ : Na ₂ O = 2.2-3.6: 1.