Investigation of Dissolution Kinetics of A Nigerian Tantalite Ore in Nitric Acid
A study of the kinetics of the dissolution of a Nigerian tantalite ore in Nitric acid has been examined. A detailed investigation on the quantitative leaching of the mineral was also carried out. The effects of some parameters such as acid concentration, contact time, temperature, particle size and the stirring rate on dissolution action have been investigated. Experimental results indicate that the dissolution rate is diffusion controlled via hydrogen ion [H + ] action, with reaction order of 0.64. About 81.3% of tantalite ore was dissolved within 120min., using 8.06M HNO 3 solution with <0.040mm particle size. Activation energy, Ea, of 22.37kJ/mole was obtained for the process. However, elemental analysis by inductively coupled-plasma mass spectrophotometry showed that the major elements in the ore are Ta(39.9%), Fe(24.9%), Ti(4.03%), S(12.4%) and Mn(2.39%). The x-ray diffractometry also confirmed the ore to exist in a single phase with tantalite characteristics peaks at 3.31A 0 , 2.55A 0 and 1.74A 0 . The ore is not radioactive by its virtue of its very low thorium and uranium contents.
Dissolution kinetics and mechanisms of reaction of Udi clay in nitric acid solution
The dissolution kinetics and mechanisms of reaction of Udi clay in nitric acid have been studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It was observed that the dissolution rate increased with decreasing particle size and solid-to-liquid ratio and increased with stirring speed, acid concentration, and leaching temperature. The experimental results indicate that the dissolution rate is chemical reaction controlled via hydrogen ion [H+] action, with reaction order of 0.31 and the reaction kinetics can be expressed as: 1 – (1 – X) 1/3 = 1.7275 x 10 4 C [HNO3] 0.3113 (dp) -0.4102 (S/L) -0.3104 (w) 0.2709 exp (-2621/T) t. The activation energy of the process was determined to be 21.791kJ/mol. The experimental data were tested by graphical and statistical methods and it was found out that the above model best fitted the data.
Kinetic Study on Catalytic Leaching of Sphalerite
This paper examines the influence of cobalt and silver ion concentration on the extraction and kinetics of zinc dissolution from sphalerite. The mechanism involves catalysis of a galvanic oxidation! reduction that produces elemental sulfur in place of SO2 gas.