Research on the strengthening mechanism of potassium leaching process to potassium feldspar

•The potassium leaching efficiency is 76 % under the conditions of 8.05 g•g−1 70 wt% H2SO4, 0.5 g•g−1 ammonium fluoride, reacting at 130 ℃ for 2 h.•Based on the ionization-hydrolysis equilibrium theory, a potassium leaching model is built.•Without considering the precipitation effect of K2SiF6 and K3AlF6, [K+] is subjected to the joint action of [H+] and [F−].•The increase of [K+] in the solution intensifies the occurrence of side reaction of potassium, inhibiting the growth of [K+].