Zircon (ZrO2·SiO2 or ZrSiO4) is the main raw material for the production of zirconium and zircon products. The origin of zircon in China is Hainan Province.
It is distributed in Guangdong province, Guangxi Zhuang autonomous Region, Shandong province, Fujian province and Taiwan Province.
The theoretical composition of zircon is ZrO2 67.01% and SiO2 32.99%.
It often contains TiCfe and other trace rare earth oxides, which make it radioactive to varying degrees due to the presence of these elements.
Therefore, necessary protective measures should be taken when using this material to produce products.
Zircon has a low thermal conductivity of 3.72W/(m.K) at 201000℃.
The expansion coefficient of zirconite is also lower than that of other crystals, which is 4.6×10-6 ℃ at 1000℃. The expansion coefficient of its single crystal is greatly different in the two directions of vertical and parallel axis (C axis).
Zircon is chemically inert and difficult to react with acids.
It reacts with glass melts to a lesser extent and is commonly used in refractories for metallurgy and the glass industry.
Natural plagioclase zircon (ZrO2) is often irregularly massive, black, brown, yellow or colorless.
There are few natural plagioclase zircon ore bodies in China.
ZrO2 used in industry, is a chemical raw material, is made of zircon (ZrO2·SiO2) by chemical method of white or slightly yellow powder.
There are three crystal types of pure ZrO2 at atmospheric pressure: monoclinic, tetragonal and cubic from low temperature to high temperature.
Stable ZrO2, according to the different degree of stability, there are partial stable ZrO2 and fully stable ZrO2, due to the fully stable ZrO2 thermal expansion coefficient is larger, its thermal shock stability is not as good as part of the stable, so the latter is often used to do ceramics and refractory toughening materials.
Take off the silicon zirconium
In the manufacture of fused cast zirconium corundum (AZS) refractory materials abroad, in addition to the use of zircon concentrate, a certain amount of “desilicrous zirconium” raw materials, its purpose: one is to adjust and stabilize the formula;
Second, improve and optimize product performance.
The original raw materials are industrial alumina, kaolin and zircon, they are finely ground and mixed evenly, semi-dry pressure ball and calcined at 3001700℃, can be made of this material.
The results show that increasing the content of zircon leads to increasing the sintering temperature, decreasing the total shrinkage and increasing the closed porosity. These reactions make sintered zircon mullite have higher density and strength and better thermal shock resistance.