AN INVESTIGATION OF LEACHING CHALCOPYRIT

The abiotic leaching behavior of a chalcopyrite ore, from Asarco's Ray-Mine, was conducted in shake flasks and miniature columns at elevated temperatures. The shake flask tests, utilizing an ore particle size of 1.18mm-2.38mm, revealed that the highest copper (Cu) extraction of 69% occurred using 1M NaCl in a 9.8g/L sulfuric acid solution at 60°C over 16 days. A secondary extraction of 59% was attained by incorporating fine pyrite at a 4:1wt ratio alongside chalcopyrite, again in a 9.8g/L sulfuric acid solution at 60°C within the same time frame. Additional flask experiments, employing various lixiviants, yielded copper extractions between 30-40% after 16 days. Mini-column tests mirrored the extraction rates across test conditions, showcasing an average rate of approximately 0.15% Cu per day, even under optimal conditions of particle size and temperature. A conceptual engineering study proposed a hot, abiotic heap-leach for low-grade chalcopyrite ore, suggesting that external heat is necessary to sustain elevated temperatures, with steam injection identified as a viable method. The requirement for an external oxidant and the economic feasibility of low-grade copper heap-leaching operations were also explored.