525 17 th International Research/Expert Conference ”Trends in the Development of Machinery and Associated Technology” TMT 2013, Istanbul, Turkey, 10-11 September 2013 THERMODYNAMIC AND KINETIC ANALYSIS OF CADMIUM SULPHIDE OXIDATION PROCESS Nada Štrbac 1 , Dragana Živković 1 , Rumen Dimitrov 2 , Boyan Boyanov 3 , Aleksandra Mitovski 1 1 University of Belgrade, Technical Faculty in Bor, VJ 12, 19210 Bor, Serbia 2 University of Chemical Technology and Metallurgy, Department - Fundamentals of Chemical Technlogy, 8 Kl.Ohridski Blvd., 1756 Sofia, Bulgaria 3 University of Plovdiv, Department of Inorganic Chemical Technology, 24 Tsar Assen Str., 4000 Plovdiv, Bulgaria ABSTRACT This paper presents the results of the cadmium sulfide oxidation roasting process from the thermodynamic and kinetic aspect. Based on the known thermodynamic values for the reactions in the Cd - S – O system, phase stability diagrams were constructed. Kinetic investigations under the non- isothermal conditions have enabled the determination of the kinetic parameters. Keywords: Cd-sulphide, oxidation, thermodynamic and kinetic analysis 1. INTRODUCTION Oxidative roasting presents one of the stages of sulphide concentrates pyrometallurgical processing. G. S. Frenc [1] systematically studied the interaction of a number of metal sulfides with oxygen; the reaction rate and sequence of individual reactions in the Me–S-O system was determined. CdS exists in two allotropic modifications: α (hexagonal) and β (cubic). The phase transition temperature of the Cd-sulfide from the sphalerite structure type β-CdS into structure of α-CdS wurtzite lies in the temperature range from 973 to 1073 K [2]. Chemistry of the cadmium sulphide oxidation process with oxygen from the air was studied by Adamiano [3]. The influence of the air on the cadmium sulfide shows the following behaviour: at 573 K, the primary oxidation products, sulfates, were detected. Further, at 873 K, CdO was discovered in the reaction products. At 973 K sulfide phase disappeared, while the amount of cadmium oxide was increased. The paper of Moldovanska et. al. [4] presents the results of Cd-sulfide oxidation in non- isothermal conditions. 2. RESULTS AND DISCUSSION For the experimental investigation the sample of cadmium sulfide was used. The sample was synthesized and prepared at the Department of Inorganic Chemical Technology "Paisiy Hilendarski" in Plovdiv, Bulgaria. Based on the known thermodynamic values for the reactions that occur in the Cd - S – O system, phase stability diagrams for this system were constructed (Figure 1).