The effect of molecular weight on the adsorption and efficacy of polysaccharide depressants

► Large molecular weight depressants destabilised the froth zone. ► Large molecular weight depressants were not good depressants of the naturally floatable gangue at low dosages. ► Small molecular weight depressants acted as better depressants of the naturally floating gangue than the large molecular weight depressants at low dosages. ► It is suggested that the large molecular weight depressants were selectively adsorbing onto the hydrophilic (pyroxene and feldspar) gangue minerals.