Processing of Wadi Qena Kaolinitic white sands by selective dispersion and leaching for industrial uses

الملخص EN

A considerable amount of -25 μm kaolin was obtained during the processing of wadi-Qena kaolinitic white sands by attrition scrubbing.

This kaolin product is obtained by desliming the kaolinitic white sand.

Such product is of a great economic application in many industries.

In this study, this product (-25 μm kaolin) was treated or beneficiated to remove colored minerals, (iron / Titanium oxides).

The treatment includes two steps.

First, the kaolin particles are dispersed and at the same time the colored mineral particles are flocculated.

The most affecting parameters in dispersion/flocculation process, flocculant dosage and pH are investigated to select its optimum values.

In this step and under optimum conditions of flocculant dosage and pH, it was possible to decrease iron oxide from 0.623% to 0.542% and titanium oxide from 1.669% to 0.924%.

Second, it was attempted to further decrease iron/titanium oxides of -25μm kaolin by acidic leaching, oxalic acid followed by sulfuric acid.

The most affecting parameters which include sulfuric acid concentration, oxalic acid concentration and leaching time.

The response surface methodology (RSM) coupled with Box- Behnken design (BBD) and analyses of variance (ANOVA) were performed to optimize the leaching process and determine the main and interaction effects.

The response factors were taken as iron oxide content and titanium oxide content.

In this context, it was found that the second order polynomial regression model is satisfactory as the predicted responses showed a good agreement with the experimental data.

The optimum conditions for sulfuric acid concentration, oxalic acid concentration and leaching time were found as 4.99 molar, 10.1 g/l and 2.28 hr.

respectively.

Under these experimental conditions, the iron oxide content and titanium oxide content in kaolin product approached 0.2 % and 0.18 % respectively.

Which assures the possibility of using such product in different industrial applications