Abstract
The article describes the characteristics of electrolytic carbon foam of aluminum production and analyzes the impact of recent changes in the technology of aluminum production on the structure of formation, composition and properties of fluorocarbon-containing wastes, reviews the currently proposed methods for their processing, substantiates the feasibility of large-scale waste processing in related industries. The paper evaluates the method of processing finely dispersed fluorocarbon-containing wastes of aluminum production using the example of a model type of raw material (pure cryolite and chiolite) and coal foam by lime milk caustification to obtain a product containing synthetic fluorite. A thermodynamic calculation was carried out and a mechanism for the causticization of wastes containing chiolite and cryolite was proposed. It is shown that when interacting with lime waste containing cryolite and chiolite, in addition to calcium fluoride, a solution of sodium aluminate is formed, which, depending on the concentration of alkali in the solution, can be supersaturated in aluminum hydroxide or sodium hydroxide. The influence of technological parameters (temperature, process time, dilution) on the completeness of causticization of raw materials is determined. Caustification of model raw materials is determined that the main influence on the efficiency of its flow is provided by the temperature of the process, which is associated with a high fluorine content in the raw material. When coal foam is caustified in the range of 60-80 °C, the temperature change does not affect the process and the CaF2 yield reaches almost 800 kg per 1 t of feedstock.
Publisher
Ivanovo State University of Chemistry and Technology