Research Investigation On The Suspended Roasting Of Molybdenite

The traditional technique of molybdenite roasting was conducted at accumulation state, which have serious problems such as, low production capacity ,long roasting time,high energy consumption, low product quality, material completes thermal transfer, react under accumulation, etc. In order to solve those problems as well as to reduce production cost, expand capacity, reduce the consumption energy, improve product quality and the stability of the production process, we introduced an advanced novel suspended roasting technology, i.e.,“Two stages roasting”. In the thesis, two types of molybdenite with quite different physical and chemical properties were used as raw materials to investigate the pre-reaction process.In this paper, the physical and chemical properties of raw materials were analyzed firstly. Then, the suspended roasting processes of two different molybdenite were investigated utilizing lab simulation facility. These studies not only provided necessary parameters for semi-industrial roasting test, but also stimulated the optimized suspended roasting parameters. In addition, the two different roasting parameters from the two type’s molybdenites were analyzed. The main conclusions are listed in the following:1. The MoS₂ from ore A belongs to type 3R,which exists as“scale-like”structure;furthermore,the MoS₂ of ore B belongs to type 2H₁,which exists as“layered”structure.2.The results of TG/DTG showed that the desulfurization temperature of ore A is between 480℃～630℃,and the desulfurization temperature of ore B is between 650℃～750℃.3. Results of the simulated suspended roasting showed that the roasting of Molybdenite is mainly influenced by the temperature, time and oxygen in the air. Residual sulfur content is decreasing with increasing in temperature,reaction time and oxygen level. It was found that reaction time is the major influencing factor,and subordinate factor is temperature. It is obvious that the influence of oxygen content is at low temperature and short roasting time.4. Molybdenum in the Molybdenite existed in the form of coexistence, which contains MoO₂、MoO₃,molybdate,etc. During the reaction, Molybdenite is converted into MoO₂ firstly,then generated MoO₃ in reaction process through further oxidation. MoO₂ was primary product in the event of low temperature and short roasting time,otherwise,MoO₃ was the major product.5. Semi-industrial （pilot） facility was established, which include gas send feeding system,heating system,suspended roasting system, cyclone separator equipment,etc. Through consecutive roasting tests,the optimized processing parameters of ore A and ore B were obtained. For ore B, the reaction temperature is in the range of 700 780℃and the oxygen content is over 8%;For ore A, the reaction temperature is in the range of 550 630℃and the oxygen content is over 8%. Under these conditions,ore B could achieve more than 50% of the desulfurization rate, and ore A could achieve more than 60% of the desulfurization rate.