Magnesium-chromium refractory products are commonly used by magnesia-chrome brick manufacturers in the non-ferrous metallurgical industry. With the continuous improvement of the raw materials and processes for the production of magnesia-chrome bricks, the varieties of magnesia-chrome refractory products are also becoming more abundant. Chrome bricks and high-quality magnesia chrome bricks, such as fused cast magnesia chrome bricks, fused magnesia chrome bricks, semi-recombined magnesia chrome bricks, and fully synthetic magnesia chrome bricks. 

About these kinds of magnesia-chromium refractory products, do you know their production process and refractoriness?

Silicate Bonded Magnesia-chrome Brick is also known as ordinary magnesia chrome brick. This kind of brick is made of chrome ore and magnesia with high content of impurities (mainly SiO2 and CaO). The firing temperature is not high, about 1550°C. The characteristics of its microstructure are: the refractory crystal grains are combined by silicate with low melting point or softening point, so it is called silicate combined magnesia chrome brick. The typical microstructure photo of silicate-bonded magnesia-chrome bricks is magnesia in gray particles and chrome ore in white middle particles. The white particles are chrome ore, and the gray round particles are magnesia. Because the silicate combined with magnesia-chrome bricks have a high firing temperature, which is greater than 1580°C, the magnesia particles contain a large amount of spinel desolvent phase.

The main crystalline phase in the matrix of silicate-bonded magnesia-chrome bricks is granular periclase, and magnesia and chrome ore particles or between the respective particles are mostly separated by off-white film-like silicate (CMS) cemented phase or pores. A small amount of composite spinel (white) is filled between the periclase crystals, but the degree of direct bonding is very low. The matrix is a dense network structure, most of the stomata are strips, and a small part of it is closed. Since the microstructure characteristics of silicate bonding are not conducive to the high-temperature mechanical properties and chemical resistance of ordinary magnesia-chromium refractory products, silicate-bonded magnesia-chrome bricks are usually used in parts that do not require harsh performance.

Facing the chromium-free cement kilns, enterprises began to research new products to replace magnesia-chrome bricks. Magnesium-iron-aluminum spinel bricks broke the dominant position of magnesia-chrome bricks in cement kiln alkaline refractories and replaced magnesia-chrome bricks in transition The position in the belt. Therefore, the basic pattern of using magnesia-chrome bricks for the firing zone and spinel bricks for the transition zone was basically established in the large-scale precalcining kiln in the 1970s.

In actual applications, a reasonable configuration of magnesia-chrome bricks should be made according to the furnace structure and working conditions. In addition to the above-mentioned magnesia-chrome bricks, magnesia-chrome ramming materials, magnesia fillers, magnesia-chrome castables and other magnesia-chrome amorphous refractories are also used in copper metallurgy thermal kilns.