Insulating refractory material for aluminum electrolysis furnace and trough construction furnace

【China Aluminum Industry Net】 Insulating refractory materials for aluminum electrolysis furnaces and tank construction furnaces mainly include the following three types:

(a) The diatomite insulation material diatomite is formed after the algae organic matter is corrupted and changed by the earth's crust. The main components of diatomaceous earth are non-crystalline silica, which is generally between 70% and 85%, and a small amount of clay impurities with a melting temperature in the range of 1000°C to 1200°C. Diatomaceous earth is composed of fine pores and its porosity can reach 85%, so it has good thermal insulation properties and is widely used as a heat insulation material.

1. Diatomite asbestos powder (chicken ash), diatomite asbestos powder is a kind of powdery insulation material, made of asbestos fiber and diatomite powder; diatomite powder accounts for 85%, fiber 2-5mm. Asbestos accounts for 14%, and 5-20mm asbestos accounts for l%. It is used to masonry insulating bricks.

2. Lightweight diatomaceous earth bricks. Lightweight diatomaceous earth bricks are shaped and dried from diatomaceous earth and additives and fired at 850°C and 900°C. Diatomite bricks have a small bulk density, large pores, and a heat resistance of 1280°C or more. Therefore, light diatomaceous earth bricks can only be used in insulation areas below 900°C, and they cannot directly touch flames. In case of high temperatures, cracks and even melting will occur.

(b) Asbestos (insulation material)

Asbestos is a natural mineral fiber that can be released into elastic fibers. According to the generation of external natural conditions can be divided into serpentine asbestos and amphibole asbestos in two major categories, the actual application of more serpentine asbestos, also known as chrysotile, its chemical formula is 3MgO • 2SiO2 • 2H2O. Asbestos sheet is made of 65% asbestos and 35% binder material and is mainly used as gasket or insulation material for equipment. Asbestos plate loss of ignition should not exceed 18%, longitudinal tensile strength should not be less than 1.4MPa. The structure and thickness of the asbestos board must be uniform, smooth surface, and uniform in the cross-section organization, and there should be no scars, voids, and cracks. The general specification of an asbestos board is 1000 x 1000mm (thickness from 1.6 to 16mm), weight is 1mm in thickness, and weight is about 1.3kg/m2. Higher use temperature does not exceed 500°C.

(3) Calcium silicate insulation products Calcium silicate insulation products are heat insulation materials mainly composed of calcium silicate hydrate. Industrially, lime and silicic acid are used as materials, and calcium silicate hydrate is synthesized by steaming in an autoclave. Then, asbestos and other fiber materials are suitably added, and a porous structure of heat insulating products is obtained after pressure molding. GB10699-89 "Calcium silicate insulation products" specifies the technical conditions of calcium silicate insulation products.