Leaching of chalcopyrite ore agglomerated with high chloride concentration and high curing periods

Accelerating Copper Leaching from Sulfide Ores in Acid-Nitrate-Chloride Media Using Agglomeration and Curing as Pretreatment

“…This is because the mineral is exposed to a high ionic charge provided by sodium nitrate, sodium chloride and sulfuric acid, which, along with a low amount of water, allow dissolution reactions to occur rapidly. This concurs with Cerda et al [48], Velásquez-Yévenes and Quezada-Reyes [21], and Velásquez-Yévenes et al [51] who found that a higher extraction was obtained with a longer repose period.…”

“…The pretreatment conditions that resulted in the highest copper extraction rate were repeated in three experiments using 3 kg of ore with the same size distribution as in the previous tests. The pretreated ore was placed in acrylic mini-columns 40 cm high and 9.5 cm in diameter, similar dimensions used by Taboada et al [50] and Velasquez-Yévenez et al [51], and left in repose for a curing time determined by the previous tests. Following the curing time, the ore was leached using a solution of 6.3 g/L NaNO 3 and seawater, with a pH of 1 (using H 2 SO 4 ), and the experimental variables as shown in Table 4.…”

“…According to Velásquez-Yévenes and Quezada-Reyes [21], the pretreatment with acid and chloride resulted in a more homogenous distribution of reactive agents in the ore, resulting in the dissolution reaction beginning earlier and the formation of soluble species, with better liquid/solid interaction and a higher degree of porosity in the bed, so that moisture is retained in the pores. Velásquez-Yévenes [51] determined that adding sodium chloride in a curing stage improves copper extraction from copper sulfate, based on a test comparing extraction with and without the addition of chloride. They demonstrated that increasing the quantity of chloride from 20 to 70 kg/ton does not significantly increase the copper extraction.…”

“…Several authors have determined that the presence of chloride ions in leaching systems improves copper extraction [6,8,9]. However, the increase in chloride concentration is not necessarily proportional to the copper extraction rate [15,51]. Table 9 shows the residual mineral species in C1 obtained by leaching test (observed with an optical microscope) in comparison to the original mineralogical state (head ore).…”

“…The authors found that the pretreatment improved extraction, which at room temperature and with 100 days of repose were 43 and 37%, respectively with brine and seawater. Velásquez Yévenes et al [51] studied the effect of adding chloride in agglomeration and a curing process to improve the copper extraction from sulfide ore in leaching by columns. The copper dissolution increased with the curing stage with chloride and acid addition.…”