To address the difficulty in separating KNO3 and NH4Cl from the metathesis products of KCl and NH4NO3,a reverse flotation process was employed,and the separation mechanism was investigated through surface wettability measurements,Fourier-transform infrared spectroscopy,and molecular dynamics simulations.The results showed that hexadecylamine (HDA) exhibited a strong collecting ability toward NH4Cl,enabling NH4Cl to float while enriching KNO3 in the underflow during flotation.After a single reverse flotation step,the underflow product achieved a yield of 75.16%,with a potassium ion content of 41.56% and a chloride ion content of 6.02%.After purification by immersion in KNO3-saturated mother liquor,the product yield increased to 85.97%,the potassium ion content rose to 46.25%,and the chloride ion content decreased to 0.76%,thereby meeting the Chinese national standard for first-grade agricultural potassium nitrate.Characterization and simulation results further revealed that HDA preferentially adsorbed onto the NH4Cl surface and enhanced its hydrophobicity,and that its interaction with the NH4Cl surface was stronger than that with the KNO3 surface.This preferential adsorption was identified as the main reason for the effective separation of KNO3 from NH4Cl.
WangG L, BianX, ShangZ R, et al. Effects of different flotation agents on the nucleation and growth of potassium chloride[J]. Molecules, 2023, 28(23):7923.
[13]
PodtynovaA S, CherepanovaM V, LanovetskiyS V. Study of the purifying flotation potassium chloride process from amines using ultrasonic treatment[J]. Izvestiya Vysshikh Uchebnykh Zavedenii Khimiya I Khimicheskaya Tekhnologiya, 2025, 68(3):86-94.
WangL J, XuY X, ChenH, et al. New insights into octadecylamine-monoacid selective adsorption on KCl/ NaCl surface:Experimental and molecular dynamic simulation[J]. Applied Surface Science, 2021, 554:149613.
[19]
PayneM C, TeterM P, AllanD C, et al. Iterative minimization techniques for abinitio total-energy calculations-molecular-dynamics and conjugate gradients[J]. Reviews of Modern Physics, 1992, 64(4):1045-1097.
[20]
ZhuY M, LuoB B, SunC Y, et al. Density functional theory study of α-Bromolauric acid adsorption on the α-quartz (101) surface[J]. Minerals Engineering, 2016, 92:72-77.
[21]
LevyH A, PetersonS W. Neutron diffraction study of the crystal structure of ammonium chloride[J]. Physical Review, 1952, 86(5):766-770.
[22]
BoskoJ T, ToddB D, SadusR J. Molecular simulation of dendrimers and their mixtures under shear:Comparison of isothermal-isobaric (NpT) and isothermal-isochoric (NVT) ensemble systems[J]. Journal of Chemical Physics, 2005, 123(3):034905.
[23]
LabikS, SmithW R. Scaled particle theory and the efficient calculation of the chemical-potential of hard-spheres in the nvt ensemble[J]. Molecular Simulation, 1994, 12(1):23-31.
PDF
(4972KB)
