Best refractory clay refers to clay with a refractoriness greater than 1580°C that can be used as refractory materials and bauxite used as refractory materials. In addition to their high refractoriness, they can maintain volume stability under high temperature conditions, and have slag resistance, resistance to rapid cooling and rapid heating, and certain mechanical strength, so they are extremely firm after calcination.

According to plasticity, ore characteristics and industrial use, Best refractory clay is divided into four types: soft clay, semi-soft clay, hard clay and high alumina clay. Soft clay is generally soil-like, easy to disperse in water, and can form plastic mud balls after mixing with liquid; semi-soft clay has poor dispersibility, and its soaked part can also form plastic mud balls after mixing with liquid . These two clays are often used as binders in the production of refractory products. Hard clay is often in the form of lumps or plates, generally does not disperse in water, has high refractoriness, and is the main raw material for refractory products. High alumina clay has high Al2O3 content, high hardness and specific gravity, and high refractoriness. It is often used to make high-grade clay products.