Evaluation on liquefaction effect of potassium dissolution extraction from low-grade solid potash ore in Qarhan Salt Lake, northern of Tibetan Plateau

Abstract

China, being the world's largest consumer of potassium fertilizer, faces significant challenges due to limited potassium reserves. Qarhan Salt Lake stands out as a reservoir containing 296 million tons of low-grade solid potash ore (KCl), establishing itself as the premier potassium fertilizer production base in China. The extraction of low-grade solid potash ore via liquefaction technology, leading to the generation of potassium-rich brine, emerges as a pivotal strategy for sustainable potash exploitation in the region. This approach offers a promising solution to mitigate the potassium salt shortage in China. This paper systematically examines the transformation in KCl content of solid potash ore within the Bieletan section of Qarhan Salt Lake before (2007) and after liquefaction (2022). The study employs quantitative assessments to determine liquefaction volume and efficiency. Results reveal that, at a shallow depth of 23.20m, the average KCl content of solid potash ore decreases from 2.15% before liquefaction to 1.00% after liquefaction. This observed decrease of 1.15% (53% reduction) underscores the substantial impact of liquefaction. A total of 136.94 million tons of KCl are dissolved, providing a sustainable resource for approximately 15 years or more. During the initial stages of liquefaction (2007-2008), a rapid decline in the KCl content of solid potash ore is noted, with liquefaction efficiency significantly influenced by the positioning of the brine mining channel. As liquefaction progresses, efficiency diminishes, although the overall efficiency surpasses that of the Huobuxun section at the eastern extremity of Qarhan Salt Lake. This study holds significant implications for refining the solid potash liquefaction mining strategy in Qarhan Salt Lake, providing valuable guidance for future optimization efforts.