Study of sulphide zinc concentrates oxidation kinetics in the fluidized bed furnace

In order to optimize the operation of the fluidized bed furnace for annealing sulphide zinc concentrates, in particular, to save oxygen for blowing, it is necessary to model thermal processes. For this purpose, the oxidation kinetics of the charge and its basic components - zinc and iron sulfides - was studied under laboratory conditions. The experiments were carried out with the simultaneous thermal analysis tool NETZSCH STA 449 F3; they showed that oxidation reactions of zinc and iron sulfides with oxygen proceed in the intrakinetic region. At the sample weight of 10 mg, the thickness of the reactant layer is less than the penetration depth of oxygen into the layer. Therefore, the expression for the change of a single particle mass can be used. It allowed one to obtain the empirical dependence for determining the reaction velocity constant during zinc concentrate annealing for further calculation of the gas generation in the fluidized bed. The authors also obtained the distribution of the oxygen concentration along the height of the charge layer and calculated the average value of the effective oxygen concentration as a function of the reactant layer thickness. The gas generation analysis in the fluidized bed during zinc concentrate annealing with the use of the obtained constants of chemical reaction velocities allowed one to obtain the formula to determine the specific consumption of the annealed zinc concentrate depending on the oxygen concentration in blowing.