مجله علوم و فنون هستهای (Nov 2012)
Determination of Optimum Process Conditions for Sulfuric Acid Dissolution of Zarigan Thorium-Uranium Ore Using Taguchi Method
Abstract
This paper deals with the study of digestion and leaching process effectiveness in thorium minerals processing, and determining the optimum process conditions for acidic leaching of thorium- uranium ores in Zarigan region to dissolve thorium. To do this, some samples from Zarygan region were studied mineralogically in laboratory. The sample containing minerals such as Anorthite, Quartz, Sanidine, Vermiculite, Albite, Gypsum, Muscovite, Anatase and Magnetite were ground in specified dimensions and then mixed with concentrated sulfuric acid. Then the mixture was heated to a high temperature. After diluting the mixture with water, it was dissolved by means of agitation leaching. The effects of different parameters such as particle size, temperature and time of digestion, concentration of sulfuric acid, and acid to ore ratio, with the aim of determining their optimum value, were studied which resulted in the following optimum values for the above-mentioned parameters: particle size of 250 μm, temperature of 180 °C, time of 5h, concentration of sulfuric acid of 10.8 mol/lit, and acid to ore ratio of 3. Under these conditions, maximum recovery of thorium was 92%. Nitric acid (oxidant) concentration effect on the recovery of thorium in the optimum conditions was studied, and for the 2M of nitric acid concentration, thorium recovery of 97% was obtained.
