China’s western region is arid to semi-arid, with low rainfall and a large water deficit. Over long-term coal mining, large quantities of mine water have gone unused because of poor quality. To address this industry pain point, the Xi’an Research Institute of China Coal Science & Technology has developed a moderate mine-water purification technology that provides a pioneering solution to improve the resource utilization efficiency of mine water and reduce environmental pollution.

Unlike traditional “one-size-fits-all” treatment approaches, the Xi’an team adopts the principles of “protecting resources at the source, staged/process-level treatment, and end-stage quality-based reuse,” with “precise demand matching” at its core, and has carried out end-to-end research and development on mine-water purification.

The institute custom-designs purification processes to match the specific water quality characteristics and reuse scenarios of different mines, avoiding the wasted costs of over-treatment and preventing environmental risks from under-treatment. They have innovated core technologies such as high-efficiency separation and intelligent control, greatly improving purification efficiency, shortening treatment cycles, reducing equipment footprint, and fitting production needs of mines of various scales so that each unit of treatment cost is used effectively. To achieve precise separation for special mine waters, the institute developed a moderate desalination nanofiltration process, pioneering a two-stage nanofiltration system that lowers mine-water salinity while cleverly retaining trace elements beneficial to human health.

The R&D team introduced a short-process in-situ purification technology for high-turbidity mine water, forming an integrated ceramic flat-sheet membrane unit. The equipment runs without chemical reagents and produces effluent quality significantly better than national standards (SS ≤ 0.5 mg/L), with low energy consumption and intelligent control. For wastewater produced by underground drilling, the team designed in-situ underground purification equipment for rig wastewater, enabling on-site treatment and recycling; the purified water can be reused for production, landscaping, and cooling, substantially improving drilling water efficiency.

The Xi’an Research Institute consistently follows the development concept that “lucid waters and lush mountains are invaluable assets.” This technology allows purified mine water to be reused underground for production, on the surface for landscaping, in circulating cooling systems, and other scenarios according to real needs. It represents an innovation in traditional water-treatment models and uses technology to support mines’ green, low-carbon transformation.