Polyacrylamides as co-depressant in hematite and quartz microflotation

Abstract

In the present study, microflotation experiments were performed on pure minerals systems involving hematite and quartz in the presence of etherdiamine as collector. The influence of polyacrylamides as co-depressant was investigated in a blend with starch depressant. The results obtained demonstrated that all the polyacrylamides used were efficient in hematite depression, at different levels and following the order of effectiveness: cationic > non-ionic > anionic. The depressant power was proportional to the degree of ionicity and the molecular weight. It is proposed that the enhanced performance is due to the presence of two functional groups, the cationic group adsorbing by electrostatic interaction and the amide group –C(=O)NH₂ adsorbing by hydrogen bonding. Non-ionic polyacrylamides indicated similar performances for different molecular weights and the proposed adsorption mechanism is hydrogen bonding associated with the amide group. Electrostatic repulsion did not have deleterious action on the adsorption of anionic polymers on hematite, nevertheless the adsorption on quartz was impaired. Polyacrylamides adsorb on quartz, although at a weaker intensity than on hematite.

Key words:
iron ore; flotation reagents; polyacrylamides