The general industrial indicators for geological evaluation of refractory clay are shown in Table 1.

Mining technical conditions: the lowest recoverable thickness of ore (true thickness), underground mining 0.8~1.0m; open mining 0.5~0.8m; stone removal thickness 0.5~0.8m; open peeling ratio ≤15.

When the content of impurities in the clay ore is high, the following indicators can be referred to:
â‘  High High quality aluminum base Clay: in addition to the general requirements, and require _{K 2 O + Na 2 O <} 1.5 ~ 2%, TiO 2 <4.5% ( manufactured by casting lower alumina products only or no load softening temperature requirements Use bricks).
2 High alkali hard clay: High alkali hard clay in some areas can also be used as refractory clay when other harmful components are low. The reference indicators are shown in Table 2.

Note: The total amount of ore impurities in the above grades should be <9%.

3 High- titanium refractory clay: In addition to the general industrial requirements, TiO ₂ <15% (high alumina clay) and TiO2 ≤7.5% (hard clay) are required.
4 High- iron hard clay: In the area lacking hard clay, or the iron of hard clay exists in the form of tuberculous pyrite, pyrite, etc., if special bricks are used, the content of Fe ₂ O ₃ The requirement may be less than 5%; if the iron is present in a dispersed state and is chemically treated, Fe ₂ O ₃ may require <14%.

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