A Multi-Parametric Investigation into Collector Adsorption and Its Role in the Chromite-Olivine Flotation System

Chromite ores that are difficult to beneficiate by gravity methods often necessitate flotation, particularly when fine particle liberation or overgrinding complicates separation. This study presents a comparative assessment of the flotation behavior of chromite and olivine through systematic microflotation tests, complemented by thermogravimetric analyses (TGA) and Fourier Transform Infrared (FTIR) spectroscopy to elucidate collector-mineral interactions. The effects of collector type (amine and sulfonate), pulp pH, collector concentration, air flow rate (AFR), conditioning time, and particle size were comprehensively investigated. Results indicated that both minerals responded similarly to amine, achieving maximum recoveries of about 80% for chromite and over 90% for olivine within the pH range of 7-8. Sulfonate proved most effective under strongly acidic conditions (pH < 2), with recoveries exceeding 75%. Across all conditions, the majority of flotation occurred within the first 30 s. Flotation efficiency improved with increasing AFR but declined with coarser particle sizes, while conditioning time had a negligible impact. TGA of the collector solutions, prepared and conditioned with each mineral at their respective optimum pH values, revealed distinct differences in thermal decomposition behavior compared with the unconditioned solutions and distilled water. These variations indicate that interactions occurred between the collector molecules and the mineral surfaces. FTIR spectra of collector-conditioned minerals rinsed with distilled water further revealed the absence of characteristic C-H peaks, indicating that adsorption was predominantly physical rather than chemical in nature.