Low-temperature oxidation of sulphide ores of sulphide-polymetallic deposits of Azerbaijan

Abstract

The article presents the results of experimental studies to determine the oxidative ac- tivity for the main industrial types of sulphide ores of sulphide-polymetallic deposits in Azerbai- jan. To calculate the amount of heat generated during oxidation, the dependences of the oxygen absorption rate on the temperature and moisture of the ore were established. It was found that with an increase in temperature above 50-80oC, absorption of oxygen slows down with time faster than at low (2.5-50oC) temperatures. If with an increase in temperature from 2.5 to 45-50oC the amount of absorbed oxygen increases by 7.5-12 times, then at a temperature from 45-50oC to 80oC it increases only by 3.6-3.7 times, which is explained by a decrease in moisture of the ore with an increase in temperature, due to evaporation. The time dependence of absorption rate of the oxygen for sulphide ores of sulphide-polymetallic deposits of Azerbaijan has a clearly pronounced break, which indicates a change in the oxidation mechanism. The oxidizing activity of sulphide ores of sulphide-polymetallic deposits of the Balakan ore field of Azerbaijan at low temperatures (2.5-800C) was studied. Determination of the oxidative activity of the main industrial types of sulphide ores of sulphide-polymetallic deposits in Azerbaijan makes it possible to classify ore reserves according to the degree of tendency to spontaneous combustion, which will allow a scientifically sound approach to planning the sequence of their development and designing mines. In addition, the article presents the results of experimental studies to determine the oxidizing activity of the sulfide ores of the Katsdag, Filizchay and Katekh deposits, carried out in laboratory conditions by the method of Institute of Mining named after A.A. Skochinsky. An indicator of oxidative activity is the oxygen absorption rate constant and labeled by the letter U (ml/g hour). The results of laboratory studies show that the oxidation of the ore leads to an increase in temperature and ignition and depends on a large number of factors such as mineralogical composition, chemical activity, humidity, temperature, fragmentation, etc. The dependence of the total amount of oxygen absorbed by sulphide ores on time at various temperatures is obtained. It has been estab- lished that with increasing temperature, the rate of oxygen absorption by sulphide ores increases. The values of the temperature coefficient (Kt < 2.0) in the temperature range of 2.5-800C show that the rate of the oxidation of sulfide ore is controlled by oxygen diffusion, and not by the rate of the chemical reaction. With equal fragmentation and equal distribution of chemical elements in ore samples, the oxidation rate is directly proportional to the outer surface of the sulphide ore.