Kinetics of potassium release of activated insoluble potassium ores

Objective To establish the kinetics model of potassium(K) release of activated insoluble potassium ores and provide the scientific evidence for reasonable evaluation and highly efficient utilization of activated insoluble potassium ores.

Method The insoluble potassium ores (potash feldspar、K-shale) were activated by the activator which was successively extracted through cation solution(NH₄⁺, Na⁺) to study the effects of cation solution on K dynamic release of activated potassium ores and the kinetic model of K release.

Result and conclusion  The results showed that there were two stages of the K release of activated potassium ores including quick release at the initial stage and slow release at the final stage. The capability of different extraction solution to release initial K from potash feldspar and activated forms was in order of NH₄Cl > NaCl > H₂O, while the K accumulative release amount was in order of NaCl > NH₄Cl≈H₂O.The total K release amount of K-shale and activated K-shale was in order of H₂O > NaCl > NH₄Cl.The first order equation, power function, parabolic diffusion equation and Elovich equation were used to describe the K release of insoluble potassium ores.The Elovich equation or power function was the best model to describe the K release of potash feldspar and activated potash feldspar, and the Elovich equation was the best model for K-shale and activated K-shale.The K release models with successive extraction of NH₄Cl were better than those of NaCl.However, the effects of two extraction solu-tions had no significant difference when using the first order equation to describe the K release of activated potash feldspar.The initial release rate, mean release rate and maximum balanced release amount of K from activated potassium ores increased significantly.The increase of initial release rate was the main reason of the increase of the maximum balanced release amount.