The effects of leaching parameters on the metal dissolutions from Caldag laterite ore using hydrochloric acid at atmospheric pressure were investigated. The following leaching parameters were examined to understand their effects on the dissolution of the metals: hydrochloric acid concentration, solid/liquid ratio, particle size, leaching temperature and time. Extractions of 95.8%Ni, 94.5%Co and 94.3%Mn into the leach solution were obtained along with a substantial amount of iron (81.5%) under the following conditions: 3.0 M HCl concentration, 90°C leaching temperature, 8 h leaching time, 1/5 solid/liquid ratio and −0.053 mm particle size. The hydrochloric acid consumption under these optimum conditions was found to be 543 kg t^–1 ore. The results indicated that hydrochloric acid concentration and leaching temperature were the most important parameters affecting metal dissolutions. It was found that the dissolution of nickel did not exhibit a good linear correlation to that of manganese, which suggested that considerable amounts of nickel were not hosted in asbolane phase but also in other mineral phases such as goethite, haematite and clays. It was, however, found that most of the cobalt appeared to be hosted in asbolane. The semi-quantitative mineral analyses revealed that mineral dissolution order was as follows: calcite > goethite > haematite > lizardite ≥ chlorite-serpentine > asbolane > albite > kaolinite.

This study investigated the effects of iron ore roasting on iron ore beneficiation. Hematite-magnetite conversion was comprehensively investigated and characterized by XRD, SEM, and M–H analyses. The magnetic susceptibilities of the materials were shown by Honda–Owen plots. The optimum magnetite transformation conditions were found as 800°C temperature, 10 wt.% coal and 10 min reaction time. Preliminary tests with the unroasted ores were conducted before the optimization and comparison tests. The Box Behnken test design was used for modeling the falcon concentrator separation tests. High-intensity wet magnetic, low-intensity dry magnetic and falcon gravity separators were applied to the roasted and unroasted ores at the optimum test conditions. After conversion, the iron concentrations in the grade that could be sold (>56% Fe) were obtained by the wet magnetic separator and the falcon gravity separator with the recovery yields of 90.87 and 81.72%, respectively. The positive effects of roasting were observed in terms of concentrate yields for the wet magnetic separation and gravity separation methods. However, desired saleable iron concentrates were not achieved by dry magnetic separation experiments, although the recovery yields were raised above 80% after the conversion process.