'n Ondersoek na die verwydering van swaarmetale uit 'n mynuitvloeisel

Abstract

The effluent from an uranium extraction plant contains dissolved metals, the most abundant being manganese (J000 ppm), aluminium (2600 ppm) and iron (2200 ppm). Large quantities of these metals are lost in the present effluent treatment process, in which the metals are precipitated as their hydroxides by the addition of lime. Water of an acceptable quality is then returned to the river. Various attempts have been made to recover the above mentioned metals. As a result of the effects of co-precipitation, the three metals present in high concentrations in the effluent, namely aluminium, manganese and iron, cannot be separated by altering the pH during a usual precipitation. This co-precipitation is caused mainly by iron-II. Treating the effluent with ozone lessens the effect o f co-precipitation substantially, because the iron-II is oxidised to iron-III . After oxidation the above mentioned metals can be separated into two fractions, the one containing iron and aluminium and the other aluminium and manganese . Although several me t hods justifiable the oretically were investigated, a practical procedure for separating the metals in the above mentioned fractions could not be found. It was then concluded that the soluble silicon in the effluent should be either removed or suppressed before any practical separation technique can be applied .