No abstract

Red Mud from domestic alumina plant contains high excess alkaline components and traces of many toxic heavy metals. The results showed that Red Mud contains as main components hematite, goethite, residual aluminium oxide-hydroxides, desilication products (DSP), TiO2 and does not contain radioactive elements such as Uranium (U), Thorium (Th). U and Th in Red Mud are less than the average concentration values of Uranium (4ppm) and Thorium (12 ppm) in the earth´s crust. Physical structural composition of domestic Red mud can be classified by an equilateral triangle iron oxide/hydroxide-sandy components-clays (23.2÷53.7% iron oxide/hydroxide; 34.1÷63.8% sandy components; 7.3÷34.1% clays). Chemical composition of red mud is, by weight (%w/w): Fe2O3Tot in the range 31.

The oxidation of low grade complex concentrates (Cu, Pb and Zn) in aqueous media (weak alkaline) oxidized nonferrous metals concentrates is carried out at high pressure. Leaching is the subsequent processing step in metal extraction. The paper studies the influence of some parameters (temperature, time, L:S ratio, excess) on the leaching efficiency of nonferrous metals from oxidized concentrate. The optimum parameters determined are: S/L ratio of 10/1, 25% reactive excess, leaching temperature of 50 o C-60 o C and reaction time of 60 minutes. Maximum leaching yield obtained at optimum parameters was 97-98 % for Cu and 82-83 % for Zn. The complete characterization (XRD analysis and the chemical analysis) of the raw materials and products was carried out to determine the composition of the initial and final phases. The experimental results look very promising and the solution containing nonferrous metals will be used in the next hydrometallurgical steps precisely in the nonferrous metals recovery.