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Based on the requirement of the new technology for producing potassium sulfate and N‐Mg compound fertilizer, boussingaultite, by the reaction of the mineral shoenite from Kunteyi Salt Lake, Qinghai province, and the industrial byproduct ammonium sulfate, the solubilities of the quaternary system (NH4)2SO4‐MgSO4‐K2SO4‐H2O at 25.0°C in the isothermal evaporation and crystallization process were measured using the isothermal evaporation method, and the corresponding phase diagrams were plotted. According to the diagram, this system contains six saturation points and six solid phase fields of crystallization, which correspond to (K1‐m,(NH4)m)2SO4, (NH4)2SO4·MgSO4·6H2O, K2SO4·MgSO4·6H2O, MgSO4·6H2O, (K1‐n,(NH4)n)2SO4·MgSO4·6H2O and MgSO4·7H2O, respectively. By analyzing and calculating the isothermal evaporation and dissolution phase diagram of this quaternary system at 25.0°C, K2SO4 and (NH4) 2SO4·MgSO4·6H2O can be separated via K2SO4·MgSO4·6H2O and (NH4)2SO4 as raw materials. Theoretical calculations about the proposed process were carried out and verified by experiment, which indicated that the yield of potassium sulfate was improved and the magnesium resources were fully utilized. [ABSTRACT FROM AUTHOR]

The composition of salt lake brine is complex, and the physical and chemical properties of Mg and Li are very close to each other, which is difficult to separate. In this paper, a new type of nanomaterial is developed based on the salt lake brine, and the Qinghai salt lake in China is used as the model. The solar evaporation-acid leaching-diaphragm electrolytic doping strategy is used to successfully separate Li and Mg. A composite metal self-supporting material is constructed during the electrodeposition process, and finally prepared MgZnCe(OH) 8 and its oxide MgZnCeO 4 are used as anode materials, and LiPF 6 is used as electrolyte. Electrochemical tests show that at a current density of 200 mA/g, the initial charge and discharge capacity are 38.71 (274.33) and 76.41 (138.78) mAh/g, but after many cycles, the capacity is steadily increased, the charge and discharge capacity is almost equal, the coulombic efficiency is as high as 100%. In particular, the MgZnCeO 4 negative electrode has an increase of nearly 3.41 (1.45) times compared with the first cycle of charge and discharge capacity after 3000 cycles. This excellent lithium storage performance is attributed to the macroscopic design of the composite metal supporting negative electrode. The special alloying reaction, Mg2+ substitution reaction, more stable spatial structure and smooth Li+ transmission channel can effectively improve the volume change, and also accelerate the lithium/dilithium dynamics. In salt lake brine, the physical and chemical properties of Mg and Li are very close to each other, which is difficult to separate. In this paper, we propose a green method for the separation and purification of Mg and Li from salt lake brine. The solar evaporation-acid leaching-diaphragm electrolytic doping strategy is used to successfully separate Li and Mg. A composite metal self-supporting material is constructed during the electrodeposition process, and finally prepared MgZnCe(OH) 8 and its oxide MgZnCeO 4 are used as anode materials, and LiPF 6 is used as electrolyte. [Display omitted] • Li and Mg are successfully separated by solar-acid leaching-membrane electrolysis, which are applied to the Li-ion battery. • The lithium dendrites can be eliminated by alloying/dealloying and Mg substitution reaction. • After 3000 cycles of MO, the charge-discharge capacity retention rate is 341 (145)%, CE is 99.5%, Rs and Rct are 15.41 and 4.3 Ω. [ABSTRACT FROM AUTHOR]