Abstract: A method of treating a plating sludge is disclosed, wherein a plating sludge, whose water content is decreased to not higher than 10% by weight, is mixed with scale, dust, both of which are formed in the alloy steel-making step, a binder and a carbonaceous material, and water is added to the mixture to adjust the water content of the mixture to 7-30% by weight, the mixture is kneaded and then molded into a briquet, and the briquet is subjected to a strength-improving treatment. The resulting briquet can be used as a raw material for ferroalloy. When the briquet is subjected to a reduction smelting to recover a metal, the metal can be used as a raw material for alloy steel.

Abstract: A hermetically sealed arc furnace for producing stainless steel is disclosed which makes use, as a main raw material, a semi-reduced chrome ore pellet and a reduced iron ore pellet and by which these pellets are melted, decarburized and finally refined under a reduced pressure said hermetically sealed arc furnace capable of adjusting its interior reduced pressure, and particularly including a vacuum-tight seal between the furnace lid and furnace body, a telescopically sealed gap between the lid and an electrode extending therethrough and an exhaust opening detachably connected to a vacuum pump for reducing the internal pressure within the furnace.

Abstract: A method of treating waste produced during stainless steel making is disclosed. The method comprises the steps of kneading a sludge cake with a mixture of dust and scale to obtain a kneaded mass, adding an organic binder and eventually adding water with an inorganic binder to said kneaded mass, shaping said kneaded mass into a briquette, and heating said briquette at a low temperature. The briquette obtained can be used as a ferroalloy making raw material.Metal oxides contained in the briquette are reduced by a dry reduction refining added with a carbonaceous reducing agent and eventually with a flux to separate usable metals.