Keywords: Non-Ferrous Metals, Loss, Lead, Slag, Fuel, Energy, Heat balance, energy efficiency,
The leading branch of non-ferrous metallurgy in Kazakhstan is the production of heavy non-ferrous metals, primarily lead and zinc. Kazakhstan ranks 8th in the world ranking of lead producers. According to research company GlobalData, the amount of refined lead produced in the world in 2020 amounted to about 4.5 Mt, which is 5.2% less than the year earlier. This volume is expected to reach 5.2 Mt by 2024. The largest new projects in the lead industry will be Abra in Australia (scheduled to launch in 2021) and Prairie Creek in Canada (to launch in 2022). The leader in the production of refined lead is China, which accounts for about half of the metal produced in the world. The European Union and the United States share the second and third places. There are significant production volumes in Asian countries such as Japan, South Korea and India.
The main problem of Kazakhstani lead production is low-quality sulphide and mixed sulphide-oxidized raw materials, which are increasingly involved in processing. Modern lead production is automated as much as possible, therefore, changing the composition of the charge causes technological problems and additional operating costs. Another urgent problem that needs to be addressed is the search for new ways to improve, modernize and intensify lead production to minimize the negative impact on the environment. Prospects in this direction are seen in the reduction of own waste through their subsequent use as secondary raw materials and increasing the energy efficiency of processes.
The purpose of the work is to monitor the heat losses of pyrometallurgical processes for the production of lead and zinc and to develop models of experimental industrial devices that will improve their energy efficiency. The authors propose to improve lead metallurgy by utilizing the irretrievably lost heat of molten materials obtained in the process of Isa smelting, reduction mine smelting and Waelz process. The molten dump slag of the lead production has a high-potential heat, reaching 1800 kJ / kg at a temperature of 1500 ° C. For this, thermodynamic, thermal calculations of the dispersion of the slag melt were carried out in order to study the process of the decomposition of a jet of a low-viscosity liquid into drops. The main directions of the development of dry granulation technology have been investigated and determined by the calculation and analytical method. Proposed a device for dry granulation of liquid slag, containing a container for molten slag with elements for directing the flow of molten slag to the granulator. The geometry of the tray - disperser has been calculated, which makes it possible to ensure the productivity of the granulator in the range of 262-488 granules / s. Trial heats were performed to confirm the calculated data. Improvement of certain metallurgical processes allows reducing the amount of emitted CO2 - in proportion to the amount of saved carbon-containing reductant. Model calculations showed that the greatest decrease in the specific consumption of energy carriers and the output of CO2 is observed when using air blast heated to 200 ° C with an increase in its flow rate from 1000 to 7000 Nm3 / h and a concomitant decrease in atmospheric air inflow. The estimated reduction in the unit costs of carbon and CO2 emissions was 30.2–35.5%, and the total unit costs of energy carriers - 28–32%. This saves about 3 billion tenge (which is $ 7 million and € 6 million).
The prospect of reducing consumption of the most expensive and scarce metallurgical fuel - coke, along with economic benefits, allows to reduce greenhouse gas emissions and minimize negative impact on the environment by reducing the volume of low-concentrated sulfur gases. As the results of industrial data show, in recent years, the technical and economic indicators of the existing scheme for the production of lead and zinc no longer meet modern requirements. Despite all the disadvantages of pyrometallurgical processing of ores and concentrates, the existing hydrometallurgical options are unsuitable for industrial implementation. Therefore, the issues of reducing heat losses during the operation of high-temperature units and, consequently, increasing their energy efficiency special attention is paid.
|Publication||Impact Factor journals|
|Affiliation of speaker||D. Serikbayev East Kazakhstan technical university|
|Position of speaker||PhD student|