There are a certain amount of micro-pore and micro-crack in the fired refractories of magnesia brick factories. These micro-pore and micro-crack can absorb heat and solve a part of thermal stress at high temperature, but at the same time, they also bring some disadvantages, that is, they are very vulnerable to penetration and excretion of smelting slag. In magnesia-carbon brick factories, compared with iron and steel industry, non-ferrous smelting has lower smelting temperature, but more slag. The slag is highly corrosive ferrite or silicate. The slag has low viscosity, low interfacial tension, strong infiltration and permeability and excretion. Therefore, after firing refractories are used in non-ferrous smelting furnace, the permeation and drainage metamorphic layer is thicker, which is prone to loose layout, strength drop, peeling and other damage. Layout spalling caused by slag permeation and discharge is an important reason for high loss and low service life of refractories in non-ferrous metallurgy.
Melt-cast magnesia-chromium bricks have peculiar good properties relative to slag penetration and drainage, because they are compact frits made by melting, pouring and group cooling. The slag can only melt in the appearance of the bricks, but not possibly appear the signs of penetration and drainage (which has been proved by the judgement of the section of the Melt-cast magnesia-chromium bricks after use). Therefore, it is very difficult and expensive to produce Melt-cast magnesia-chrome bricks. In the key parts of non-ferrous smelting furnaces in developed countries, there are still places where other refractories can not be replaced.
While developing and introducing the advanced smelting skills, it is necessary to develop refractories for oxygen-enriched smelting skills, especially magnesia-chrome bricks. It is necessary to digest and absorb the introduced skills and speed up the process of localization.
The production process of Melt-cast magnesia-chromium brick is totally different from the general production essentials of sintered refractories. It uses magnesia and chromium ore to participate in certain amount of additives and confusing ingredients, melts in the arc furnace, pours into the mould, controls cooling annealing, produces mother bricks, upside down cutting, grinding, drilling and cold processing, and produces the necessary bricks. Magnesia chrome brick