Journal of Engineering Science and Technology (Dec 2009)
INVESTIGATION OF THE OPTIMUM DISSOLUTION TEMPERATURES OF PHOSPHORUS IN SULPHURIC, NITRIC AND OXALIC ACID SOLUTIONS DURING LEACHING OF IRON OXIDE ORE
Abstract
Studies were carried out to determine the optimum dissolution temperatures of phosphorus in oxalic, nitric and sulphuric acid solutions during leaching of iron oxide ore. Phosphorus dissolution rates and dissolution per unit rise in temperature were determined and compared to ascertain the preferred acid in terms of effective dephosphorization of iron oxide ore using leaching process. The results of the investigation show that the optimum dissolution temperatures of phosphorus in these acids were found to be 45, 55 and 70ºC respectively. Phosphorus dissolutions per unit rise in temperature in these acid solutions during the increasing and decreasing stage of dissolution were 9.4 and -3.07 mg/kg/ºC 2.88 and -4.7 mg/kg/ºC and also 2.16 and -7.95 mg/kg/ºC respectively. Phosphorus dissolution rates in these acid solutions during the increasing and decreasing stage of dissolution were also determined as 0.67 and -0.13 mg/kg/s, 0.14 and -0.19 mg/kg/s and also 0.1 and 0.44 mg/kg/s for oxalic, nitric and sulphuric acid solutions respectively. This confers to oxalic acid a better dissolution power on phosphorus over nitric and sulphuric acid, followed by nitric acid.
