Abstract:In the process of electric furnace copper smelting, a proper thickness of the furnace accretion can form a protective layer on the furnace body, while a much larger one would lead to a great reduction of the effective volume ratio of the furnace and increase of copper content in the slag. The determination of thickness of the furnace accretion and high copper content in the slag are two major technical issues in electric furnace copper smelting production, and also the final way to increase the capacity of electric furnaces. By analyzing the composition and properties of the furnace accretion in this paper, it is concluded that the content of Fe3O4 in slag is the key to the thickness of furnace accretion. The high content of Fe3O4 not only increases the mechanical entraining of copper in slag, but also increases the loss of chemical dissolution of copper in slag. By analyzing the thermodynamic and kinetic conditions of the reduction and decomposition of Fe3O4 effective measures to reduce the content of Fe3O4 in the slag are given in this paper: diesel oil, white sand and N2 are sprayed into the bottom of the furnace by a small oil gun; When the volume ratio of oil to gas ranges from 1∶17 to 1∶20, the optimal insertion depth of oil gun is 0.2~0.3m when the Fe3O4 in reducing slag is reduced, the oil gun is inserted into 1/2~3/5 of the slag layer thickness when the copper content in slag is reduced, and the oil gun is inserted into the bottom of furnace and then lifted 50~100mm when the furnace accretion is treated. Besides a proper control on the ratio of raw materials, Na2CO3 flux with slag content of 1.6‰ should be added in proportion. When this scheme was carried out, it is found that the thickness of the furnace accretion is reduced to an average of 452mm, and the copper content of the slag is reduced to a monthly average of 0.498%, indicating a good economic benefit.
