Alkaline gelatinised locust bean gum: alternative depressant for pyroxene and talc in Platreef ore

Abstract Carboxymethyl cellulose (CMC) is the common depressant used in flotation. However, CMC has a high negative charge density. Thus, a higher electrostatic repulsion on negatively charged minerals. Also, it is susceptible to pulp ionic strength. Hence, the high dose requirements for effective depression. This is detrimental as CMC destabilises the froth at high dosages. Locust bean gum (LBG) brings attractive attributes like low charge density and insensitivity to pulp ionic strength. Therefore, this paper explored the feasibility of using alkaline gelatinised LBG as a CMC alternative depressant for pyroxene and talc. Bench flotation tests were conducted using Platreef ore to compare LBG and CMC's performance at 25g/t, 50g/t, and 100g/t. This study showed that LBG and CMC yielded comparable pyroxene and talc depression (> 80%) at all dosages tested. Furthermore, at 100g/t, the respective Pt recoveries of 88% and 83% illustrated that LBG was more effective than CMC at allowing Pt to float unhindered. Additionally, zeta potential measurements were conducted in the presence and absence of the depressant to establish the adsorption mechanisms. The zeta potential results showed that CMC and LBG adsorption onto pyroxene and talc surfaces were different due to their structural and ionic strength differences.