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Method of reducing metal oxide in a rotary hearth furnace (14) to make a feed stock for a refining vessel when manufacturing alloyed iron, alloyed steel or stainless steel. The rotary hearth furnace includes an annular inner refractory wall (32), an annular outer refractory wall (34), an annular ref

Method of reducing metal oxide in a rotary hearth furnace (14) to make a feed stock for a refining vessel when manufacturing alloyed iron, alloyed steel or stainless steel. The rotary hearth furnace includes an annular inner refractory wall (32), an annular outer refractory wall (34), an annular refractory platform (33) between the two walls. Stationary fuel burners (36, 40) are mounted to walls (32, 34) at a position just above an upper surface of the platform. A mixture of a metal oxide and a carbonaceous reductant is placed onto the upper surface of the platform and rotated past the burners. The oxide is heated by an oxidizing flame. Thereafter, a second layer of a reductant is charged over the hot first layer, and both layers are heated for an additional period of time to a temperature of at least 1300°C. to reduce the metal oxide. The metal oxide may be chromium ore, chromium ore concentrate, nickel ore, nickel ore concentrate and stainless steel flue dust. The reductant may be coal or coke. The reduced metals provide inexpensive metal units for alloying with molten iron.

대표청구항 ▼

A method of reducing metal oxide, comprising: providing a furnace having an annular platform and at least one fuel burner, placing a fast layer of a mixture containing a reductant and oxygen-bound chromium and iron onto an upper surface of the platform, rotating the platform past the burner to heat

A method of reducing metal oxide, comprising: providing a furnace having an annular platform and at least one fuel burner, placing a fast layer of a mixture containing a reductant and oxygen-bound chromium and iron onto an upper surface of the platform, rotating the platform past the burner to heat the first layer with an oxidizing flame to a temperature of at 1200°C., charging a second layer of the reductant covering the heated first layer, continue heating the layers to at least 1300°C. to partially reduce the oxygen-bound chromium and iron, the partially reduced mixture containing at least 40% chromium or a chromium carbide and at least 70% of iron or an iron carbide, whereby the second layer prevents reoxidation of the chromium or iron within the furnace, providing a refining vessel containing an iron bath, feeding the partially reduced mixture into the bath, refining the bath until the oxygen-bound chromium and oxygen-bound iron are reduced to chromium and iron thereby forming a stainless steel.