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Acta of Turin Polytechnic University in Tashkent

Abstract

The article analyzes the scientific problems of the copper industry. In particular, the main problem with the classical production of copper is the causes of large amounts of slag and the negative impact of these wastes on the environment. Accordingly, the main component that forms the slag is iron, and the higher its content in the original copper concentrate, the more slag is formed, and at the same time a large amount of copper metal is released into the waste. The departure is indicated by evidence. To prevent this problem, a technology has been proposed to reduce copper sulfide concentrates by first oxidizing them in a “Hot Layer” furnace at 850 ◦ C and then using ammonia vapors. The recovery process was carried out in a Waelz furnace (or rotary tube furnace) using a stepwise recovery method in the temperature range of 550 - 1000 ◦C. The results of chemical and phase analysis of samples taken from laboratory and semi-industrial experiments in the process are presented in the form of tables and XRD. The results were discussed and the thermodynamic possibilities of the process were studied. During the reduction process, the equilibrium states of the reactions of the oxides with ammonia vapors were studied and it was concluded that the temperature inside the furnace should be kept around 677 ◦C for the process to flow optimally.

First Page

INTRODUCTION AND LITERATURE REVIEW It is known that 85% of the world’s copper is obtained by pyrometallurgy and 10-15% by hydrometallurgy. The choice of technology for copper production depends primarily on the mineral form of the copper in the ore. For example, if the ore contains copper in the form of complete sulfides, then, of course, pyrometallurgical methods are used [1]. If in the form of oxides, then hydrometallurgical or combined methods are used. In addition, metallurgical production also depends on the natural, economic and geological potential of the region, i.e. the availability of coke, natural gas and similar natural resources required for production is important [2, 3]. Most enterprises around the world, such as the Almalyk Mining and Metallurgical Combine (AMMC, Uzbekistan), use the classic pyrometallurgical scheme of blister copper production. Accordingly, copper sulphide ores are first en- riched by flotation to obtain a concentrate containing 16-20% copper. The obtained copper concentrate is loaded into met- allurgical furnaces for thermal processing at high tempera- tures [4]. Metallurgical plants have several types of smelt- ing furnaces designed to process copper raw materials. Ex- amples include smelting furnaces such as the Reverberatory, the Oxygen Torch, and the Vanyukov Furnaces. Although the principles of operation of these smelting furnaces are differ- ent, the products are similar, such as copper matte (30-50% Cu), slag and industrial gases. The intermediate product is copper, which is converted into matte, where blister copper (96-98% Cu) is obtained by oxidizing unnecessary elements in the matte in the presence of atmospheric oxygen. The blis- ter copper is then poured into anode molds during electroly- sis and sent for electrolysis, resulting in high-quality copper cathodes (99.99% Cu) [5, 6, 7, 8, 9, 10].

Last Page

CONCLUSION Based on the analysis of waste-free and innovative meth- ods of reduction of oxidized copper-iron concentrates, the main possibilities of extraction of metals from rich copper concentrates were identified. The most convenient way to implement this technology is a Waelz furnace (or rotary kiln), which uses ammonia vapor as a reducing agent. The basic parameters of the furnace required to ensure the flow of the process are indicated. This method made it possible to ex- tract both copper metal and metallized iron raw materials from oxidized copper concentrates in one go. In addition, the loss of precious metals in copper concentrate with waste - slag was prevented. The chemical composition and mineralogical composition of the semi-finished product obtained by oxidative roasting of copper sulfide concentrate were determined. According to this, the main component is copper (I) –ferrite in the system. The reduction of oxidized copper concentrate with ammo- nia vapors increased the separation of metals from the fin- ished product. The main reason for this is that the system does not produce slag that is difficult to process. The specific chemical reactions that take place during the recovery process, their mechanism and thermodynamic ca- pabilities are described. Factors that negatively affect the speed of the process and ways to overcome them were discussed and an optimal tem- perature of 950 K (677 oC ) was selected to improve the flow of the reduction process.

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