Raw material in glass production -aluminum hydroxide supplier,manufacture

1.Quartz sand

The content of SiO2 in glass is very high, usually 50-80%, and 70-75% in ordinary bottles, glassware and plate glass.In quartz glass up to more than 98%.SiO2 forms a skeleton in the glass, giving the glass good chemical stability, thermal stability, transparency, higher softening temperature, hardness and mechanical strength.But when the content increases, the melting temperature increases and the viscosity of the glass solution increases.

Na2O is a good flux, which can react with SiO2 at a low temperature to form silicate, which can reduce the viscosity of glass liquid and accelerate the melting speed of glass.However, Na2O will weaken the structural strength of glass, increase the thermal expansion coefficient of glass, and reduce the thermal stability, chemical stability and mechanical strength of glass.Therefore, the total amount of Na2O and K2O in the glass composition cannot be higher than 16%.The raw materials for the introduction of Na2O are soda ash and mirabilite Na2SO4.

Soda ash (Na2CO3) is a fine white powder that melts easily in water.The impurities contain sodium chloride, sodium sulfate, iron oxide, etc.Soda ash is easy to deliquescence, caking, not conducive to the mixing of materials.Accordingly, must store in ventilated and dry storehouse inside.In melting, a foam called ‘scum’ may form on the surface of the glass.The quality requirement for soda ash is (%);Na2CO3 & gt;98, NaCl<1, Na2SO4 & lt;0.1, Fe2O3 & lt;0.1.

Soda ash has light alkali and heavy alkali.In the domestic use of light alkali, light alkali density is small (0.61), fine grain.The mixed materials are prone to stratification in the transportation process. After entering the kiln, they are easy to be taken into the regenerator by the airflow in the kiln, resulting in the blocking and melting of the lattice brick.And the bulk density of the heavy base is 0.94), coarse grain.Therefore, the use of heavy alkali is one of the measures to improve the quality of the compound and reduce alkali dust.

Mirabilite (Na2SO4) has a specific gravity of 2.7 white powder.Divided into anhydrous mirabilite and water mirabilite (na2so4.10h2o) two.Mirabilite containing water began to separate out the crystalline water into a paste above 35℃, it is not convenient to use.To do this, boil or bake in advance.The melting point of mirabilite is 884℃, the boiling point is 1430℃, its decomposition temperature is higher, in melting, if there is reducing agent, can greatly reduce the decomposition temperature of mirabilite.For this reason, it is necessary to add pulverized coal when using mirabilite.The theoretical amount of coal is 4% of mirabilite.

Mirabilite can not only substitute for alkali, but also be a commonly used clarifier.The use of mirabilite also has the following disadvantages;Compared with soda ash, its heat consumption is large, this is because quartz sand and mirabilite to react at a higher temperature, and the speed is slower;Mirabilite, which has been melted but not reacted, floats on the surface of the glass and is easy to produce mirabilite bubbles.The erosion of refractory is also large, especially when there is awn water;The melting of mirerite mixture must be carried out in reducing atmosphere, but when the amount of pulverized coal is too much, the Fe2 o 3 will be reduced to Fe S and become brown.Accordingly, the dosage of mirabilite has certain limitation.The quality requirement for mirabilite is (%);Na2SO4 & gt;85, NaCl<2, the CaSO4 & lt;4, Fe2O3 & lt;0.3, H2O & lt;5.

2 aluminum hydroxide

The Al2O3 content in jar glass, glassware glass and plate glass is 2-3% and the highest is 8-10%.In silicate glass containing alkali metal and alkali earth metal oxides, adding a small amount of Al2O3 can reduce the tendency of crystallization of glass, improve the chemical stability, thermal stability and mechanical strength of glass, reduce the erosion of glass to refractory materials, and expand the scope of glass forming operation.Al2O3 is introduced from feldspar, kaolin, pyrophyllite and industrial alumina.

Aluminum hydroxide is purer than calcined aluminum oxide, and it is easy to melt and clarify, but it is expensive, easy to absorb water and cause the fluctuation of composition.In order to reduce foam, an appropriate amount of fluorite or cryolite can be added to the mixture.

3.1 introduction of Ca O raw materials

The main role of Ca O in glass is to increase the chemical stability and mechanical strength of glass.However, when the content is too high, the glass is easy to crystallize, so the content of Ca O in the glass is generally not more than 12.5%.At high temperature, Ca O can reduce the viscosity of the glass liquid and accelerate the melting and clarification of the glass, but at low temperature, the viscosity will increase rapidly, which brings difficulties to the forming operation.The raw materials of Ca O are limestone, calcite and chalk.

Limestone, mostly gray, light yellow, light red, rarely white, its color and iron oxide content high and low.

Calcite it is higher than limestone purity, when glass composition requirements are strictly controlled calcite can be used.