Ministry of Higher and Secondary Special Education of the Republic of Uzbekistan Almalyk branch of Tashkent State Technical University named after Islam Karimov Faculty of Energy and Mechanical Engineering Department of Chemical Technology

Firing of zinc concentrates in “BL” furnaces

•  The first stage of the technological scheme for producing Zn is the firing of Zn concentrates in BL furnaces, the main purpose of which is the conversion of insoluble ZnS into water-soluble ZnO. Firing allows you to apply hydrometallurgical technology to the processing of zinc concentrates. When firing, they seek to obtain a cinder that meets the requirements of subsequent hydrometallurgical processes. It is very important that the firing product is powdered.
• Many domestic plants process concentrates of not one, but several concentration plants. Such concentrates often differ in both chemical and particle size distribution. Therefore, the concentrates of different deposits are averaged before firing. Sometimes concentrates are dehydrated to a pulp state (> 30% moisture). A pulp mixture is preferable when the zinc plant is located next to the concentrating plant, or when concentrates of very different composition go into the mixture. However, the loading of pulp moistens the exhaust gases, and this complicates their processing, increases the corrosion of equipment and exhaust systems. The pulp is more difficult than a dry charge to evenly distribute in a fluidized bed.
• Currently, industry is firing in highly productive, economical and automated fluidized bed furnaces. With it, as a rule, there is a device for dust collection, called a cyclone. They are intended for rough cleaning of gases from dust, capable of reducing the dust content of exhaust gases from 140-160 to 3-6 g / m2 in one step. After cyclones with various types of exhaust fans, the exhaust gases are sent through a dirty gas collector for fine cleaning of dust, which allows reducing dust content to 0.1-0.2 g / m2.