Ceramic information
20 19- 1 1-29 20:40
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Magnesium oxide is an important fluxing component in ceramic production. By introducing it, the physical and chemical properties of ceramics can be improved in a certain range of use and the firing temperature of ceramics can be reduced.
From the point of view of cooling, we can consider adding more raw materials such as feldspar to the formula to reduce the firing temperature. However, if magnesium oxide is used instead of some alkali metal oxides, the mixed alkali effect can effectively improve the properties of glass phase in ceramic structure under the same cooling effect, thus enhancing the physical and chemical properties of ceramics. Therefore, it is very necessary to introduce some magnesium oxide into ceramic body and glaze purposefully.
1
At present, talc, dolomite and magnesite are the main imported raw materials of magnesium oxide in building ceramics market. Among them, talc is the most commonly used and widely used in green bodies and glazes. Dolomite is used in some ceramic bodies and glazes. Magnesite is rarely used in China, and it has been reported abroad that magnesite has a good effect.
▲ Talc (Source: Network)
China's talc reserves are very rich, and several famous producing areas are Liaoning, Guangxi, Jiangxi and Shandong.
Guangxi talc includes white talc and red talc. Its calcined talc product has excellent quality;
Haicheng talc is the most famous talc in Liaoning, and its talc is mainly used to select high-purity talc for medical and cosmetic industries. At present, a large part of Liaoning talc we use is "burnt talc" calcined from ore ingredients;
Shandong talc is mostly white talc with good taste;
Jiangxi talc, represented by Guangfeng black talc, temporarily fell into a production suspension period, which led to a sharp rise in domestic talc prices;
There are a lot of talc in other provinces, but it has not been developed, or its reserves are low, or its taste is poor, which has not reached the well-known level.
2
In the process of using talc, it will be different because of its mineral morphology.
Talc in Jiangxi is a product with high silicon and low magnesium, accompanied by a small amount of carbon. Therefore, in use, except for a few occurrences, most of the associated minerals are clay, sepiolite and other minerals, so ball milling is easier. In terms of dosage, due to its associated carbon raw materials, attention should be paid to the scope of use. When the dosage is large, the color of the product may change, and even the phenomenon of incomplete black center of organic matter combustion may appear.
Talc in Haicheng, Liaoning Province has a long history of use and a high reputation, and the high-end talc brand has high value. Therefore, its products in ceramic industry are mostly mixed calcined products, that is, low-grade talc and a large number of magnesite are mixed and calcined in proportion at the right time. It is difficult to ensure the completion of the calcination reaction in the calcination process, and a large amount of magnesium oxide and time remain. Therefore, due to the existence of a large amount of residual magnesium oxide, its initial melting temperature is low, and ball milling is relatively difficult. Burn slippery in the market