A green process for recovering nickel from nickeliferous laterite ores

A novel process was proposed for recovering nickel from nickeliferous laterite ores. First of all, silicon and magnesium were removed from lateritic ore by high concentration sodium hydroxide leaching and carbonation respectively, so as to enrich nickel. Then the method of ammonia carbonate leaching was adopted to recover nickel from the carbonized slag, and the remaining residue was used as a raw material for recovering iron. The effects of temperature, ammonia carbonate concentration, liquid/solid ratio and stirring speed on the recovery of nickel were examined. When the leached residue reacted with ammonia carbonate (6 mol·L−1) in a ratio of liquid-to-solid of 5:1 at 60 °C for 150 min at the stirring speed of 300 r·min−1, approximate more than 95% nickel was recovered. During the whole process, there was no contamination produced and the chemical raw materials were recycled, thus the process was a green technology that having good social benefit.