Recovery of zinc and lead from Yahyali non-sulphide flotation tailing by sequential acidic and sodium hydroxide leaching in the presence of potassium sodium tartrate

The recovery of zinc and lead from Yahyali non-sulphide flotation tailing using sulfuric acid followed by sodium hydroxide leaching in the presence of potassium sodium tartrate was experimentally investigated.In the acidic leaching stage,the effects of pH,solid-to-liquid ratio and temperature on the dissolution of zinc from the tailing were explored.82.3%Zn dissolution was achieved at a pH of 2,a temperature of 40°C,a solid-to-liquid ratio of 20%and a leaching time of 2 h,whereas the iron and lead dissolutions were determined to be less than 0.5%.The sulfuric acid consumption was found to be 110.6 kg/t(dry tailing).The leaching temperature had no beneficial effect on the dissolution of zinc from the tailing.The acidic leach solution was subjected to an electrowinning test.The cathode product consisted of 99.8%Zn and 0.15%Fe.In the alkaline leaching stage,the Pb dissolution increased slightly in the presence of potassium sodium tartrate.More than 60%of Pb was taken into the leach solution when the leaching temperature increased from 40 to 80°C.The final leach residue was analyzed by XRD and XRF.The XRD results indicated that the major peaks originated from the goethite and quartz while minor peaks stem from smithsonite and cerussite.The XRF analysis demonstrated that the residue contained 70.3%iron oxide.Based on the sequential leaching experiments,the zinc and lead were excellently depleted from the flotation tailing,leaving a considerable amount of iron in the final residue.

Dissolution of lateritic nickel ore using ascorbic acid as synergistic reagent in sulphuric acid solution

The dissolution of nickel and cobalt from Caldag lateritic nickel ore using the combination of sulphuric and ascorbic acids was investigated. The use of other organic acids, namely citric, maleic and stearic acids, as synergistic reagents was studied for comparison. The results revealed that the use of ascorbic and citric acids markedly improved the dissolution of cobalt compared to the other two organic acids that only showed slight synergistic effect on the leaching rate. In terms of nickel dissolution, ascorbic acid is the most effective synergist, followed by citric, maleic and stearic acids in descending order. Under the most optimized conditions found in this study, i.e., using 1 mol/L of sulphuric acid with the presence of 4 g/L of ascorbic acid at 80 ℃and solid-to-liquid ratio of 1/10, more than 99% and 98% leaching rates of cobalt and nickel, respectively, can be achieved within 4 h of leaching. In addition, the leaching performance is relatively insensitive to the change of ascorbic acid concentration from 2 to 4 g/L which is highly desirable from operational perspective.

Dissolution behavior of Caldag lateritic nickel ore subjected to a sequential organic acid leaching method

The dissolution behavior of Caldag lateritic nickel ore subjected to a sequential organic acid leaching method was investigated. The effects of the type of organic acid, acid concentration, leaching time, and leaching temperature on the lateritic nickel ore were examined. Organic acids were used individually prior to sequential leaching. Citric acid was more effective than the other two acids for the selective leaching of nickel and cobalt. An increase in the citric acid concentration negligibly affected the dissolution of the metals, whereas temperature exhibited a strong beneficial effect. Oxalic acid was determined to be the most appropriate organic acid for the second leaching step. After 8 h（4 h ＋ 4 h） of leaching with organic acids（0.5 M citric ＋ 0.5 M oxalic） in sequence at 90°C, 89.63% Ni, 82.89% Co, and 69.63% Fe were leached from the lateritic nickel ore. A sequential citric ＋ oxalic acid leaching method could represent a viable alternative for the dissolution of metals from lateritic nickel ore.