Synergetic effect of cottonseed fatty acid salt and nonionic surfactant NP-4 in the froth flotation of siliceous-calcareous phosphate rock

Abstract

Fatty acid is constricted when used in phosphate flotation alone as a collector due to its high reagent consumption and low separation efficiency. When fatty acids are mixed with other surfactants, the flotation performance can be greatly enhanced because of the synergetic effect, and therefore, widely adopted in industry. The cottonseed fatty acid salt (CSFA) and nonionic surfactant of NP-4 mixture was used in the upgrading of phosphate ores in this study. Batch flotation tests, droplet size distribution of CSFA, zeta potential measurements and X-ray photoelectron spectroscopy were conducted to elucidate the synergistic mechanism between the two surfactants. It was found that NP-4 improved the emulsification of CSFA and can reduce the adverse effect of calcium ion concentrations, which may otherwise be detrimental to CSFA. When mix CSFA with 10 wt% NP-4, an optimum separation between apatite and dolomite or quartz and lower reagent consumption were observed in flotation of siliceous-calcareous phosphate ore. With the aid of zeta potential measurement and XPS analysis, the adsorption behaviors of CSFA and NP-4 on the surfaces of apatite, dolomite and quartz was revealed. NP-4 enhanced the adsorption of CSFA on the surface of apatite and dolomite but decreased its adsorption on quartz, indicating that CSFA and NP-4 were co-adsorbed on surfaces of apatite and dolomite whereas in a competitive adsorption on the quartz surfaces.