The smelting and converting El Teniente process for copper concentrates as well as slag cleaning furnace technologies to treat slags coming out from the El Teniente furnaces are widely applied today in Chile and around the world. Several industrial applications of this process have shown their ability to treat copper concentrates in a wide range of chemical and mineralogical compositions. Main operational parameters determining performance of the process are: oxygen enriched air flow rate; degree of oxygen enrichment; moisture content of the solid materials processed; molten material levels inside the vessel; frequency of molten materials tapping; bath temperature; and copper losses in slags. In this work, the copper losses in the slags from the El Teniente pyrometallurgical process are predicted by calculation from thermodynamic data and compared with those determined by microscopic examination and slag industrial data. Results obtained show that the main part of copper losses in the slag from the El Teniente furnace are mechanically entrapped or floated unsettled droplets of the co-existing matte phase. Conversely, the very low copper losses in the slag from the slag cleaning furnace are limited by the physicochemical form.I. Imris is in the

The Chilean copper smelters are producing large amount of copper slags. These copper slags are deposited at landfills. In the present time, a huge amount of copper slags are accumulated in Chile. The main problem with landfilling is not only the land space, area which is used for copper slags deposition every year, but many environmental problems, high disposal and transport cost are associated with the landfilling of these slags. Therefore, the focus of environmental policy is now into waste minimization and recycling to minimize transport and disposal cost, saving resources as well as land space. Copper slag contains many useful metals and slag making oxides, which can be recovered and recycled by a high temperature direct reduction process. The laboratory scale tests show that by suggested high temperature direct reduction of copper slags two products can be obtained, a Fe–Cu–C alloy with precious metals content and an inert slag with low metal content. The Fe–Cu–C alloy can be used for metal production and inert slag for cement production similar to blast furnace slags. Suggested high temperature direct reduction process for copper slags treatment is commercially feasible and environmentally friendly without any solid or liquid waste.

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Purpose -This paper aims to describe a solution for cyclonic flue dust recycling based on the example of ferrochromium producers in Kazakhstan. It includes environmental improvement, which can be assessed in detail based on LCA after the development of a feasibility study of such a proposal. Design/methodology/approach -Three pyrometallurgical recycling approaches should be achieved. The first approach is reduction smelting of fine waste in a direct current arc furnace without preliminary agglomeration. The second is reduction smelting of agglomerated waste in a submerged arc furnace, and the third is processing of agglomerated waste with liquid cast iron. The last approach facilitates the reactions of metal oxide reduction by carbon and silicon from the iron with a corresponding decrease in energy and auxiliary material consumption. Findings -Valuable material can be produced from ferrochromium dust waste using environmentally friendly technology, including electric furnaces that can operate in SAF regimes and a simple plasma high-power DC reactor operating under a neutral or reducing atmosphere. Finally, the investigation of waste recycling has developed a novel approach that facilitates metal oxide reduction and provides low energy and auxiliary materials consumption. Practical implications -Research into the treatment of flue dust generated in the ferrochromium industry is needed to solve environmental problems not only in Kazakhstan but also in all ferrochromium plants in the world. Originality/value -The three proposed pyrometallurgical recycling approaches should be achieved on a large scale.