Copper Smelting Flash Furnace Refractory

Flash smelting is one of the most advanced copper ore smelting technique. During flash smelting, dry sulfurized fine ore powder, flux, oxygen or oxygen rich air or preheated air are injected into high temperature reaction tower hearth, the ore powder quickly realizes desulfurization, smelting, slag forming and so on. The molten metal enters into sediment bath for further slag making, and the concentrated metal can separate with slag. Flashing smelting furnace is self heating equipment, the heat is generated from sulfur oxidization in concentrate ore. This copper smelting technique combines roasting smelting and some blowing smelting together, has very high smelting intensity.

The reaction in flash furnace features intense and fast reaction speed, large thermal release intensity and complex furnace atmosphere, so the requirement on furnace lining refracotries is very high. Flash furnaces can be divided into Outokumpu flash furnace and Inco flash furnace. They are both composed of cylindrical reaction tower, sediment bath and cylindrical flue.

Reaction tower

Reaction tower is the most important part of flash furnace, air flow containing concentrate ore powder is injected into tower from the top, the chemical reaction of ore powder is carried out in a transient and melts into molten flow, which enters into sediment bath with high speed. Thus, tower lining would suffer severe scouring, erosion and abrasion caused by air current and high temperature high speed molten metal. The inner lining of reaction tower usually adopts magnesia chrome bricks, the steel shell of reaction tower are cooled by spraying cold water. At upper part of reaction tower, temperature is about 900~1100℃, oxygen partial pressure is high, so Fe3O4 protection layer is formed at tower wall, so direct bonded magnesia chrome bricks can be used here. At middle and lower part of reaction tower, the temperature is relatively high, about 1350~1550℃, and this part should endure the scouring, erosion and abrasion of molten metal. So fused cast magnesia chrome bricks are used as lining bricks, and water cooling jacket is installed at this part. Tower top are built by sintered magnesia chrome bricks.

Sediment bath

Sediment bath is rectangular molten bath, with 2.5~5m height, 3~10m length. The function of sediment bath is to further finish slag making reaction and separate molten metal. The working environment of sediment bath refractory is also very harsh, the end wall and side wall of sediment bath also suffers the scouring and erosion of high speed high temperature air current and molten metal. Especially slag line zone furnace wall, which would be scoured by continuously  waving molten metal, and is the most quickly damaged part. So slag line magnesia chrome refractories should have good sulfur permeation resistance and slag erosion resistance. Sediment bath bottom should not only bear load but also endure high temperature and chemical corrosion, so rebounded magnesia chrome bricks can be used here.

Smoke flue

Smoke flue mainly suffers high temperature smoke current (containing molten slag and dust) scouring and erosion, so direct bonded magnesia chrome bricks are usually used.

For some parts, where has complicated structure or difficult for the masonry of firebricks, high quality magnesia chrome castable is usually used.