Mineralogical analysis of rising flue slag in an oxygen-enriched double-side-blowing copper bath smelting furnace
The buildup of soot slag in the rising flue of an oxygen-enriched double-side-blowing copper bath smelting furnace poses a significant challenge,blocking the flue,which is a key factor restricting the production of high load and high operation rate of the smelting furnace for an extended period.The chemical composition,phase composition,and microscopic morphology of the rising flue slagging soot of the oxygen-rich double-side-blowing copperbath smelting furnace were investigated through X-ray fluorescence spectrometer,X-ray diffractometer,scanning electron microscope and electron probe microanalyzer.The results show that the main elements of the flue dust are Fe,Cu,Pb,Zn and O,and the main phases are(Cu,Zn,Fe)Fe2O4 and Fe3O4,exhibiting a dense,poreless surface microscopic morphology.Considering the working conditions of the production process,the causes of rising flue slagging were analyzed.During the production process of the oxygen-enriched double-sided-blowing copperbath smelting furnace,the oxygen-enriched air was drummed into the melting bath through the nozzle,and the melt was vigorously stirred.The resultant air bubbles in the melt rupture and lead to the formation and spattering of small slag and copper matte particles in hot airflow into the rising flue.The slag and copper matte are then oxidized to a high melting point(Cu,Zn,Fe)Fe2O4 and Fe3O4,in the wall of the flue in the cold condensation to form flue slag.At the same time,considering the low moisture content of raw materials,while the smelting furnace operates at negative pressure,the un-reacted copper concentrate or other raw material powders were transferred to the high-temperature section of the rising flue by the flue gas.These materials could generate bonded slag due to oxidation.In addition,volatile substances in raw materials,such as Pb,Zn and As,in the rising flue could be oxidized into low melting point compounds and then bonded with high melting point(Cu,Zn,Fe)Fe2O4 and Fe3O4 to form dense slag soot.Therefore,to mitigate flue slagging in the smelting production process,it is recommended to control the moisture content and impurity levels of raw materials,control the slag type and melting temperature to reduce the melt spattering and use the nozzle to burn the heavy oil for melting the flue slag,to ensure stable and efficient production operations.