Acta Petrologica et Mineralogica

The shallow section of Mahai Salt Lake in the Qaidam Basin holds significant reserves of low-grade solid potassium salt resources, which provide resource security for the production of 100 000 tons/year of potassium fertilizer through water-soluble mining and solid-liquid conversion methods. With the continuous progress of water-soluble mining operations, the grade of solid potassium ore in the northern part of the Mahai mining area has further decreased, which brings great challenges to the adjustment of salt field and mineral processing. In order to make full use of this resource, this paper systematically carried out the indoor ore dissolution simulation experiment based on the low-grade solid potash ore samples near the shallow ore layers of boreholes 9-13 and 9-3 in Mahai Salt Lake, with burial depths of 0~3 m. The experimental results show that: ① When the KCl grade of solid potassium ore is low, the degree of the solvent should be appropriately increased, which is conducive to the dissolution of K⁺ ions and the concentration of K⁺ in the dissolution solution. ② The concentration of Na+ in the solvent is too low to dissolve the salt layer skeleton, but the high concentration of Na⁺ will lead to the salt concentration. In the production, the Baume degree of the solvent should be adjusted according to the actual situation of the K⁺ content of the dissolution solution. ③ As the grade of solid potassium ore in the Mahai mining area continues to decrease, when the concentration of K⁺ reaches the production requirement of the salt field, the concentration of Na⁺ in the sodium brine pool will significantly increase. The relative concentration of SO^2-₄ in brine also increase accordingly, the precipitation of rock salt from the sodium brine pool stage will significantly increase, and the composition of the brine entering the mineralization pool will also undergo significant changes. This may have a significant impact on salt field production. The above experimental results can provide reference for the optimization of solvents in salt field production.

low-grade solid potassium salt; KCl grade; solvent; dissolution experiment; Mahai Salt Lake