As of September 15, a modified coal-based solid waste defluoridation agent and its production equipment, independently developed by CHN Energy, completed industrial production validation at the Bu’ertai Coal Mine of Shendong Coal. A total of 20,000 kg of the defluoridation agent has been produced, and the agent will subsequently be used for on-site defluoridation of mine water.
At present, high-fluoride mine water is generally treated by adsorption, mainly hydroxyapatite adsorption and resin adsorption. These technologies are plagued by high material costs. Their treatment performance is vulnerable to raw-water pH values and coexisting ions, resulting in unstable effluent quality, making it difficult to meet the needs of large-scale mine water treatment.
To address these problems, CHN Energy proposed a “treating waste with waste” approach and developed a “one-step solid-phase method” for preparing a modified coal-based solid waste defluoridation agent. Using coal-based solid wastes including coal gangue and fly ash from the Shendong mining area as raw materials, the technology employs a mechanochemical solid-phase reaction to enable aluminum-based modifying reagents to form new chemical bonds with silicon and aluminum elements in the coal-based solid waste, thereby reconstructing the surface crystalline phase of the solid waste and producing a novel defluoridation agent.
Compared with conventional defluoridation adsorbents, this agent is better suited to the water quality conditions of the Shendong mining area. In mine water defluoridation, it requires no additional pH adjustment or pre-turbidity removal, can stably reduce fluoride content in mine water to below 1 mg/L, and achieve one-step removal of fluoride and suspended solids. According to testing and assessment by a third-party institution, the sludge formed after treatment is general industrial solid waste with controllable environmental risks. The agent can be used for underground treatment of fluoride-containing mine water. Combined with technologies including underground backfill mining, it can achieve the dual goals of low-cost defluoridation of mine water and resource utilization of coal-based solid waste.
In addition, CHN Energy independently developed a production device for the modified coal-based solid waste defluoridation agent based on an improved vibrating ball mill, overcoming the bottlenecks of low throughput and discontinuous production associated with conventional vibrating ball mills. Following three months of industrial -scale validation, stable production of the defluoridation agent has been realized, fully verifying the reliability of the technology.
