Advantages and disadvantages of flash smelting

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　Flash smelting was first used in 1949 by the Finnish company Outokumpu. This method uses oxygen-enriched air or hot air to spray the dry concentrate into the reaction chamber of the flash furnace, causing the concentrate ions to remain suspended in the high-temperature oxidative gas flow, where rapid oxidation reactions of the sulfide minerals occur, releasing a large amount of heat. Due to the oxidation reaction of metal sulfides, the SO2 concentration in the flue gas rises to over 10%, which facilitates sulfur recovery and environmental protection. In flash smelting, the oxidation reaction of copper ore occurs rapidly, releasing a large amount of heat per unit time – heat that can account for 42–50% of the total heat generated. This accelerates the smelting process and significantly increases its productivity, which is twice that of smelting in reverberatory or electric furnaces. The fuel consumption of a flash furnace is only 1/2 to 1/3 of that in a reverberatory furnace. In some factories that employ oxygen-enriched processes, the heat generated by the reaction of the concentrate can account for over 60% of the total heat output, **reducing fuel consumption. Flash smelting is an advanced smelting technology that has been developed in modern times. It features low energy consumption and large-scale operation, along with favorable working conditions, a high level of automation, and high labor productivity. Its metal recovery rate is even higher than that of traditional wet zinc smelting processes; it can also handle lead-zinc mixed concentrates that are difficult to separate, producing both lead and zinc at the same time, thereby overcoming the disadvantage of indirect heating associated with traditional pyrometallurgical zinc smelting. The main drawback of flash smelting is that the slag contains a large amount of the base metal, which must be depleted and recovered. The second phase of the Jinchuan project adopted the flash smelting process during melting. The original design called for a processing capacity of 50 tons per hour for the dry concentrate; this process made use of a flash furnace equipped with a depletion zone. It came online in 1992, and through years of continuous efforts, its technical and economic parameters met the design requirements. High-load industrial tests were conducted starting in March 2004, and these tests revealed that there were still many difficulties in further increasing the load of the flash furnace:  The distribution of heat generated by reactions within the furnace was not optimal, resulting in consistently high temperatures in the low-nickel matte, which reached up to 1280°C – a situation that posed a direct threat to the safety of the furnace ；  When the concentration of oxygen-enriched air exceeds 65%, severe clogging occurs at the outlet of the concentrate nozzle, and the rate of clogging is high; a large amount of labor is required for cleaning and maintenance, just enough to keep production going ；  The nickel, copper, and cobalt contents in the slag discarded after furnace operation are out of control, averaging 0.37% with a maximum value of 0.74%, which reduces the recovery rate of valuable metals ；  The slag accumulation within the reaction tower is uneven, and the temperature at certain areas of the tower wall is too high, posing a threat to the safe operation of the reaction tower ；  The brick lining of the rising flue is severely damaged, as are the bricks forming the flat top and side walls of the flue; currently, high-pressure axial flow fans are used for forced cooling. Therefore, to increase the production capacity of the flash furnace, it is necessary to simulate the operation of the nickel flash furnace and further optimize its operations.