Development of fused cast magnesia chrome refractories

There are certain amount of micro pores and microcracks between the refractories in general firing refractories. These micro pores and microcracks can absorb heating and relieve a part of thermal stress at high temperature, but at the same time, they also bring some disadvantages, that is, they are very easy to be infiltrated and discharged by smelting slag. Compared with the iron and steel industry, the smelting temperature of nonferrous smelting is relatively low, but the amount of slag is large. The slag is a highly corrosive ferrite or silicate, with low viscosity, low interfacial tension, and strong wettability and permeability. Therefore, after the fired refractories are used in the nonferrous smelting furnace, the permeability and discharge metamorphic layers are relatively thick, which are prone to damage such as loose layout, strength drop and spalling. It is an important reason for high consumption and low service life of refractory materials in nonferrous smelting that slag infiltration and discharge lead to spalling.

Application of magnesia chrome brick

Compared with the damage mechanism of slag infiltration and discharge, the fused cast magnesia chrome brick has a peculiar good performance. Because it is a dense frit made by melting, pouring and group cooling, the slag can only have erosion effect on the surface of the brick, and there is no sign of infiltration and excretion (this has been proved by the section judgment of the used fused cast magnesia chrome brick). Therefore, although it is difficult to produce cast magnesia chrome brick, and the price of magnesia alumina chrome brick is expensive, it is still used in the key parts of nonferrous smelting furnace in developed countries, where other refractory materials can not be replaced.

Oxygen enriched flash smelting and oxygen enriched bath smelting are the advanced non-ferrous metal smelting skills in the world now. The matching characteristics of these new smelting technologies are oxygen enriched blast and intensified smelting. As a result, lining refractories suffer from very harsh utilization conditions, and the existing domestic refractories are still difficult to meet these utilization requirements. In addition to opening up and introducing the smelting skills of the predecessors, it is necessary to develop refractory materials for oxygen enriched smelting technology, especially for melting and casting magnesia chrome bricks. It is necessary to digest and absorb the imported skills and speed up the process of localization.

The production process of fused cast magnesia chrome brick is completely different from the general production essentials of sintered refractory materials. It uses magnesia and chromite to join certain amount of additives and mix up ingredients, melts in electric arc furnace, casts into mould, controls cooling and annealing, produces mother brick, and makes necessary brick shape through final cutting, grinding, drilling and cold working. Magnesia chrome brick