11:16 a.m., July 23rd, with the hot slag from the reduction furnace poured into the melting furnace, the side-blowing melting furnace of the Zinc Leaching Residue Project undertaken by China ENFI Engineering Corporation through an EPC contract with Huize Subsidary of Yunnan Chihong Zinc Germanium Co., Ltd was successfully put into production.

Zinc leaching residue from zinc smelters is a kind of hazardous bulk industrial waste listed in the National Catalogue of Hazardous Wastes, which, if treated in the traditional approach, may lead to high energy consumption, low recovery rate and difficulties in further treatment of semi-finished products. To find a safe and environmental-friendly way to treat zinc leaching residue and solve this problem confronted by the whole world, in 2008 China ENFI worked with the Owner and carried out experiments in using the side-blowing furnace to treat zinc leaching residue. After ten years of industrial experiment and solution verification, numerous breakthroughs have been made through continuous efforts in overcoming the technological challenges, which laid a solid foundation for the feasibility study initiated in 2017 and the subsequent design and construction efforts.

In this project, zinc leaching residue is treated by integrated process equipment that enables both hazardous waste disposal and resource utilization. The melting temperature is increased from the precious 1200℃ to 1300℃-1400℃. Latest production data shows that the treatment capacity of this production line has exceeded the designed value. In conjunction with the downstream cleaning operation of the fuming furnace, the actual standard coal consumption per ton of residue in this production line is 30% to 40% lower than the standard coal consumption in pyrometallurgical treatment of residue.The successful startup of this project means that China ENFI has made a major breakthrough in industrial application of Side-Submerged Combustion Smelting Process (SSC), which will provide a reliable technological support for the treatment of industrial solid waste and hazardous waste in association with lead-zinc oxide ore, nickel laterite, titano-magnetite as well as copper-nickel sludge and tin-containing sludge, etc., lead the progress of this technology and fulfill environmental protection through innovation.

Further reading：

The Side-Submerged Combustion Smelting Process (SSC) employs multiple side-blowing lances to inject oxygen-enriched air and fuel into the bath at a high speed, so as to vigorously stir the melt and supply heat to the melt by direct combustion. When the feed is added to the smelting zone, carbonate or sulfate will be quickly dispersed in the melt as it is stirred and conduct heat transfer and mass transfer with surrounding melt to facilitate the heating, decomposing and melting of the feed.

At present, the Side-Submerged Combustion Smelting Process (SSC) has been commercially applied in reduction of molten lead-rich slag, treatment of solid wastes of and recovery of metal values from lead paste of waste lead-acid batteries, wastes from non-ferrous metal smelting, zinc-leaching residue and copper concentrate. This process is highly adaptable to a wide range of materials, especially in treatment of non-exothermic materials, playing an important role in pushing forward the technological advance of non-ferrous metal metallurgy, energy efficiency and environmental protection.