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2 Physicochemical Problems of Mineral Processing

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Photon attenuation properties of concretes containing magnetite and limonite ores

Gur A., Artig B., Cakir T.

Physicochemical Problems of Mineral Processing

2017

Vol. 53, iss. 1

184--191

In this study, gamma shielding properties of concretes containing magnetite and limonite ores at different ratios (5%, 10%, 15%, 20%, and 30%) were investigated by using a 60Co (1.25 MeV) radioactive source which was built in Thratron 1000E™ device used for radiotherapy purposes. Then, the photon transmission values (I/I0) were measured by 0.6 cm3, farmer type, PTW™ ion chamber. The dose readings (I0 and I), made by PTW™ Unidose Electrometer, were used to calculate the linear attenuation coefficient (, cm-1), the mean free path (, cm), and the mass attenuation coefficient (, cm2/g) by the Lambert equations, and the results were compared with the calculations obtained using the WinXCom computer program. The findings from this study revealed that the concretes containing magnetite and limonite ores were more effective than the ordinary concrete in the attenuation of gamma rays. It was determined that the values of the mean free path decreased with the increasing concentrations of magnetite and limonite ores while the linear attenuation coefficients for 10 concrete blocks increased with the increasing magnetite and limonite ore concentrations. A comparison of the theoretical values obtained from the WinXCom computer program and the experimental results revealed a good level of conformity.

Investigation of kinetics and mechanism of priceite leaching in sulphuric acid solutions

Gur A.

Physicochemical Problems of Mineral Processing

2015

Vol. 51, iss. 2

719--730

The leaching kinetics and mechanism of priceite having the formula of 4CaO5B2O37H2O was investigated in sulphuric acid solutions. For the dissolution process, the effects of reaction temperature, sulphuric acid solution concentration, solid/liquid ratio, particle size, and stirring speed were investigated as effective parameters for the experiments. The experimental data indicated that the dissolution rate increased with the increasing reaction temperature, the decreasing particle size, and the solid/liquid ratio. The conversion rate increased up to 1.0 mol/dm3 with the increasing acid concentration, and then decreased with the increasing acid concentration over concentrations of 1 mol/dm3. It was also determined that the stirring speed had no significant effect on the dissolution rate. The dissolution process of priceite in sulphuric acid solution was tested with regard to heterogeneous and homogeneous reaction models, and it was found that the dissolution rate was controlled by first order pseudo-homogeneous reaction model. The activation energy of the dissolution process was determined as 26.07 kJmol-1. The results were evaluated graphically and statistically. The experimental data were found to fit well with the mathematical model.