Refractory material scheme for mineral thermal reduction furnace

Refractory materials for mineral thermal reduction furnace include three parts: refractory materials for furnace top, refractory materials for furnace wall and refractory materials for molten pool (furnace slope and furnace bottom). Refractories in different parts are in different working states during ferroalloy smelting.

The top refractory material is mainly influenced by the impact effect of high temperature furnace gas and spray slag, temperature change between feeding intervals, radiant heat of high temperature arc light, air impact and pressure change in material collapse.

The refractory material of furnace wall is mainly subjected to high temperature radiation of arc and temperature change during feeding interval. Erosion impact of high-temperature furnace gas and spray slag; Impact wear of solid material and semi-molten material; Serious slag erosion and slag impact near the slag line. In addition, when the furnace tilts, it is subjected to additional pressure.

The refractories in the furnace slope and bottom mainly bear the pressure of the upper charge or molten iron; Temperature change, charge impact and arc melting during intermittent feeding; Erosion impact of hot iron and slag at high temperature.

In order to ensure the normal operation of the electric furnace, it is necessary to choose refractory materials with high refractoriness and softening temperature under load, good resistance to rapid cold and heat, good resistance to slag, large heat capacity and certain thermal conductivity to lay the electric furnace lining.

The performance and application characteristics of refractory materials for furnace lining used in ferroalloy production are as follows.

1 the clay brick

The main raw material for making clay bricks is refractory clay with good plasticity and binding force.

The main characteristics of clay brick are: it has strong resistance to acid slag, good resistance to cold and heat, good insulation ability and certain insulation performance; Low refractoriness and softening temperature under load. Clay brick should not be used directly under high temperature conditions and special requirements.

In ferroalloy production, clay bricks are mainly used for lining of furnace wall in exposed part of ore furnace, outer lining of furnace wall and bottom for heat preservation and insulation or lining of molten iron ladle.

2 high alumina brick

The main raw material of high alumina brick is high bauxite and the binder is refractory clay.

Compared with clay brick, the biggest advantage of high aluminum brick is refractoriness, load softening degree is high, slag resistance is good, mechanical strength. The disadvantage is that the resistance of high aluminum brick is not good.

In ferroalloy production, high-alumina bricks can be used to lay the lining bricks for the outlet of ore furnace, the top of electric refining furnace, and also to blast the lining of molten iron ladle.

3.Magnesia brick and magnesia

Magnesite is the main raw material for making magnesite bricks, and the binder is water and brine or sulfite pulp waste liquid.

The main performance characteristics of magnesia brick are: high refractoriness, excellent resistance to alkaline slag; But the thermal conductivity coefficient and high temperature conductivity coefficient is large, and the softening temperature under load is low, cold and heat resistance is poor. Pulverization occurs when subjected to water or steam at high temperatures.

In ferroalloy production, magnesia brick is used for laying the furnace wall and bottom of high carbon ferrochrome reduction furnace, medium and low carbon ferrochrome converter, shaking furnace and refining furnace, as well as the lining of molten iron that holds ferrochrome and medium and low carbon ferromanganese. Use magnesium-aluminum bricks instead of magnesium-aluminum bricks to build the furnace roof. Magnesia refractoriness is very high. In ferroalloy production, magnesia is often used for knotting furnace bottom, making and repairing furnace wall and furnace bottom, and can be used as a material for plugging holes or making knotting ingot mold.

4 carbon bricks

The main raw materials for making carbon bricks are broken coke and anthracite, and the binder is coal tar or asphalt.

Compared with other common refractory materials, carbon bricks not only have high compressive strength, low coefficient of thermal expansion, good wear resistance, high refractoriness and softening temperature under load, good resistance to hot and cold, but also excellent slag resistance. Therefore, all smelting is not afraid of carburizing ferroalloy varieties, can use carbon brick as the lining material of mineral furnace.

However, carbon bricks are easy to oxidize at high temperature, and their coefficient of thermal conductivity and conductivity are both large. In ferroalloy production, carbon bricks are mainly used for laying furnace wall and furnace bottom which are not exposed to air.