Sustainable phosphate mining: Enhancing efficiency in mining and pre-beneficiation processes

Abstract

Phosphate holds a critical role as a vital, limited, strategic, and irreplaceable resource. Throughout its production chain, residual phosphate can be found in waste streams. This study aims to enhance production efficiency by exploring methods to limit residual phosphate presence in waste stocks. It investigates the presence of residual phosphate in a phosphate mining site. The presence of residual phosphate throughout the production chain is investigated. Through meticulous analyses of extraction, destoning, and screening processes, the study identifies three primary stages where residual phosphate exists, the study simulates different scenarios of residual phosphate recovery and prevention. The principal data sources are data from mining site, recent literature, and information from a lithological log, the study meticulously analyzes the extraction, crushing, and sieving processes to assess the persistence of residual phosphate. The production chain diagnostic revealed that 76% of resource present is recovered (either integrated into the value chain or stored in the mine for future use), from which 8% goes to the destoning waste rocks (75% of which is residual phosphate) and the screening waste rocks (72% of which is residual phosphate), with an average grade that reaches 25% P₂O₅. Approximately, 24% of the initial phosphate rock (with an average grade of 22% P₂O₅) remains as residual phosphate which is retained in the spoil piles. To recover and prevent the presence of residual phosphate, the study proposes four new scenarios for improvement, including an integrated scenario where all the solutions are combined for a comprehensive approach. Both quantity and grade of recovered residual phosphate are assessed in each scenario. To evaluate these enhancements, the study utilizes the AnyLogic software to simulate existing process configuration and the maximal recovery of each scenario. The current flowsheet indicates that extracted phosphate can be directed either to pre-beneficiation and expedition or stored for future use. By prioritizing the extraction of phosphate over the final product, the simulation results suggest that implementing these novel scenarios could potentially save 25% of the total phosphate resource and increase storage by twofold, preserving phosphate that would otherwise be unused. This recovered phosphate can then be destined to various uses, meeting the company's present or future needs. Considering this, the study opts to keep stocks separated based on their grades and avoid mixing new phosphate streams with the final product. The implications of this research extend to sustainable mining practices, with direct ramifications for environmental impact mitigation and the conservation of valuable resources.

Keywords: Phosphate preservation; Phosphate recovery; Phosphate waste rock; Sustainable mining; System dynamics simulation.