Surface dissolution of scheelite under different regulators and its effect on flotation behavior

•Surface dissolution and flotation of scheelite in different regulators was studied.•The heat of dissolution and reaction with the NaOL were measured by microcalorimetry.•The heat of dissolution and reaction with NaOL is greater in Na2CO3 than others.•Scheelite can expose more Ca2+ active sites in Na2CO3 system than other systems.•Na2CO3 + Na2SiO3 system can improve the flotation rate of scheelite. The dissolution behavior of scheelite in Na2CO3, Na2SiO3, and Na2CO3 + Na2SiO3 systems and its effect on scheelite flotation were studied by single mineral flotation tests, TOC, ICP, XPS, FBRM and microcalorimetry. The results show that the recovery of scheelite by flotation of Na2CO3 as a regulator is best at low collector concentrations, while the flotation rate is the highest in the Na2CO3 + Na2SiO3 system. The microcalorimetry results showed that the reaction between NaOL and scheelite was exothermic, and the reaction heat was the highest in the Na2CO3 system (Q = 35.60 mJ), which is mutually verified with the TOC detection results. At low collector concentrations, XPS revealed that SiO(OH)3− adsorbed on the scheelite surface in the Na2SiO3 and Na2CO3 + Na2SiO3 systems, resulting decreases scheelite recovery, and the scheelite surface Ca/W value is the largest in the Na2CO3 system, which indicates that there are the most Ca2+ active sites on the scheelite surface, which increases scheelite recovery. The reasons for the difference in the flotation rate of scheelite among the three regulators were discussed by FBRM monitoring and zeta potential measurement. The results show that NaOL has a flocculation effect on scheelite, and the electrostatic repulsion force on the scheelite surface is the largest in the Na2CO3 system, which is not conducive to flocculation between particles and makes the floating rate of particles relatively small.