Light-burning powder is a highly active alkaline oxide obtained from magnesite after a certain temperature of light burning. 97 fused magnesia is usually processed into 100-325 mesh fine powder for sale. Concentrate powder price is the main component of magnesia-chrome brick. Magnesium oxide often contains oxide impurities such as iron, manganese, aluminum, calcium and silicon, commonly known as "light burnt magnesium". Converting light-burning powder into high-purity ultra-fine magnesium oxide through deep finishing can greatly improve economic efficiency and increase product added value. The light-burning powder is used as a raw material to obtain a pure magnesium solution by removing impurities, and then a precipitating agent is added to obtain a basic magnesium carbonate precursor, and the precursor is calcined and decomposed to obtain a high-purity magnesium oxide having a purity of 98.3%. The method has the characteristics of short process flow, simple operation, low investment, easy availability of raw materials, low product cost and good economic benefit. Raw materials for the production of magnesia-chrome bricks include natural raw materials, synthetic raw materials, industrial chromium oxide and industrial alumina. Natural raw materials: such as various grades of sintered magnesia, ordinary chrome ore and chromium concentrate with low impurity content. Synthetic raw material: a co-sintered magnesia-chrome material obtained by finely grinding, mixing, compacting and then calcining magnesia and chrome concentrate; and electroforming from magnesite and chrome ore. Magnesium chrome; also fused magnesia. The synthetic material should generally be a raw material with a low impurity content. The above materials are used differently. The combination and formula can be made into a variety of magnesia chrome bricks, and the factory is not willing to explain its formula. Therefore, the variety and name of magnesia chrome bricks are messy and confusing. According to the existing names of magnesia chrome bricks at home and abroad, the following can be standardized.

(1) ordinary magnesia chrome brick

This brick is made of chrome ore and magnesia with more impurities (SiO2 and CaO). The firing temperature is not high at around 1550 °C. The microstructure of the brick is characterized by the combination of silicates between the refractory grains. The fine powder of the refractory brick produced by the method is a magnesium chrome material which is ground, mixed, compacted, calcined by ordinary chrome ore and magnesia, and is still combined with silicate. However, the performance is improved compared with ordinary magnesia bricks.

(2) Directly combined with magnesia bricks

Directly combined with magnesia chrome bricks, made of chrome concentrate with low impurity content and purer magnesia. The firing temperature is above 1700 °C. The structural feature of the refractory brick is that there is much direct contact between the refractory grains. Therefore, its high temperature performance, erosion resistance and erosion resistance are better than ordinary magnesia chrome bricks.

(3) Recombined magnesia chrome brick

Magnesia chrome bricks made from synthetic raw materials co-sintered magnesia or fused magnesia (or partially fused magnesia) are often referred to as recombined magnesia chrome bricks. In China, only the magnesia chrome bricks made of fused magnesia chrome are called recombined magnesia chrome bricks. In order to be more consistent with the international, it is advisable to use co-sintered magnesia chrome bricks and electrofusion materials in combination with magnesia chrome bricks or fused granules and then combined with magnesia chrome bricks. In combination with magnesia-chrome bricks, since the brick making materials are relatively pure, they need to be fired at a high temperature of 1750 ° C or higher. Its microstructure is characterized by uniform distribution of components such as spinel and direct contact between refractory grains. It is better than the first two kinds of magnesia chrome bricks in terms of erosion resistance and erosion resistance. The high-quality magnesia chrome bricks we developed for the nickel-smelting converter tuyères are also classified as refractory bricks because the raw materials used are all synthetic materials.

(4) semi-recombined magnesia chrome brick

According to the above meaning of combining magnesia-chrome bricks, as long as synthetic raw materials are used as granules, magnesia-chrome bricks made of chrome concentrate and magnesia as fine powder should be called semi-recombined magnesia chrome bricks. In the domestic, the fused magnesia-chromium material is used as the granule, and the magnesia-chrome brick prepared by using the eutectic material as the fine powder or the chrome concentrate powder and the magnesia powder as the mixed fine powder is called a semi-recombined magnesia chrome brick. In order to distinguish, the magnesia chrome brick made of electro-melt granules and co-sintered magnesia chrome as fine powder can be called fused-co-sintered magnesia chrome brick. Such refractory bricks are also fired at a high temperature above 1700 ° C, and the refractory grains in the bricks are also directly combined. The advantage is that the thermal shock resistance is good, and the erosion resistance and erosion resistance are also good.

(5) Casting magnesia chrome brick

The magnesia and chrome ore are added with a certain amount of admixture, mixed, compacted and burnt, broken into blocks, melted into an electric arc furnace, injected into the mold, and annealed to produce a mother brick; the mother brick is cut, milled, etc. The type of refractory brick required for processing. The structural characteristics of the fused cast magnesia chrome bricks are uniform distribution of components, direct contact between the refractory grains, and silicates in the form of islands. Such refractory bricks are particularly resistant to melt ablation, penetration and erosion. It is a product specially developed for non-ferrous smelting. It is suitable for laying in the continuous production equipment smelting furnace, such as the lower part of the flash furnace reaction tower and the slag line area of the sedimentation tank.

(6) Chemical combination of non-burned magnesia chrome bricks

Generally, magnesia and chrome ore are used as brick raw materials, and magnesia chrome bricks are pressed with sodium polyphosphate or sodium hexametaphosphate or water glass as a binder. It does not need to be fired at a high temperature and is only baked at a temperature of about 200 °C. Since the refractory brick is not fired at a high temperature, the magnesia in the brick is hydrated, so the refractory brick cannot be stored for a long period of time. Since chrome ore has a small shrinkage when used at high temperatures, it can be used as a raw material for non-burning bricks.