Flocculation and flotation characteristics of fine hematite with sodium oleate

Flocculation and flotation characteristics of fine hematite with sodium oleate have been investigated through electrophoretic mobility, surface hydrophobic properties, adsorption measurement, flocculation and flotation experiments. A clear region of flocculation can be obtained over a wide pH range depending on oleate concentrations. Increasing the oleate concentrations results in more stable flocculation as well as the expansion of the pH range for flocculation. The conditions for good flocculation appear to be a complex function of oleate concentration, pH and oleate solution chemistry. At oleate concentration of 10(-5)-10(-4) mol/dm(3) and in acidic conditions, the electrostatic interaction between the negatively charged oleic acid emulsion and the positively charged hematite seems to be a main mechanism for flocculation. Other flocculation mechanisms are postulated for the different conditions of the system. The flotation response of flocculated hematite takes place in a similar pH range where flocculation occurs. The recovery is almost constant and low in the acidic pH range and increases above neutral pH with the maximum at pH 9-9.5. (C) 2003 Elsevier B.V. All rights reserved.