METHOD FOR PROCESSING NICKEL LATERITE ORES RESULTING IN THE DIRECT PRODUCTION OF FERRONICKEL

摘要

The invention relates to the field of non-ferrous metallurgy, and more particularly to a method for processing nickel laterite ores resulting in the direct production of ferronickel in the form of metal granules. Processing nickel laterite ores involves grinding an ore, for example a high-magnesia ore, a solid carbonaceous reducing agent and flux additives, mixing same to produce a charge, subjecting said charge to reduction roasting in a two-stage apparatus consisting of two rotating furnaces interconnected by a transfer chamber, cooling the resulting clinker, and isolating ferronickel from the ground clinker. The flux additives include, in terms of the mass of the ore, 3.5-6.5% СаО, 1.5-10% SiO₂, 1-5.5% Al₂O₃ and 0-0.75%, in terms of F₂, fluorine-containing additives. Various calcium-, silicon-, aluminium- and fluorine-containing materials can be used as flux additives, for example limestone, blast furnace slag, clay, low-grade high-silica bauxites, aluminium-containing slags, fluorite, spent cryolite electrolyte, and other enrichment and metal wastes. Kaolin clay containing a minimum of 15-30% Al₂O₃ and 50-75% SiO₂ can be used in an amount of 3-18% of the mass of the ore as SiO₂ and Al₂O₃additives. The solid carbonaceous reducing agent, for example coke breeze, lignite, coal, anthracite or a combination thereof, is introduced in an amount of 6-12% of the mass of the ore, the mixture is briquetted, the briquettes reduced in the first furnace and having a temperature of 1000-1100°C are charged via the transfer chamber into the second furnace, directly into a bath of molten slag. At the same time, a solid reducing agent, namely coke breeze or anthracite, is supplied to the feed zone of the second furnace in an amount of 4-8% of the mass of the ore. The temperature of the melt in the second furnace is maintained within a range of 1275-1350°С, preferably 1275-1325°С. The advantages of the method are reduced energy consumption and improved technical and economic performance indicators.