On the mechanisms of beryl flotation in the presence of some metallic cations

Abstract

This paper presents some aspects of the fundamentals of beryl flotation with sodium dodecyl sulphate (SDS) and sodium petroleum sulphonate (SPS) collectors, as well as the influence of the presence of metallic cations and superficial leaching of the mineral with cold HCl and with HCl and HF on the floatability. Zeta potential studies and Hallimond tube tests were carried out on beryl samples pretreated with HCl, and with Hcl and HF. Zeta potential determinations showed that the isoelectric point (IEP) of beryl is around pH = 2.7. The pretreatment of beryl with HCl displaced the IEP to a value around pH = 2.3 while the HCl and HF pretreated beryl reached an IEP close to pH = 3.7. The presence of metallic cations, such as Fe 3+, Al 3+, Ca 2+ and Mg 2+ in the system, strongly affected the mineral surface potential for both pretreatments. The results of microflotation tests with SDS and SPS in the absence of metallic cations indicated, for HCl pretreated beryl, that floatability is significant for pH values below the IEP. Pretreatment with HCl and HF increased the floatability of beryl in the range of pH between 2 and 10. Metal hydroxi-complexes added to the system had an activating effect on the mineral, while colloidal metal hydroxides acted as depressants. The mechanism of adsorption is similar for all metallic cations studied and is related to the adsorption of the anion RSO 4 − or RSO 3 − on the sites where specific adsorption of the metal hydroxi-complexes has occurred.