Abstract
The Glycine Leaching Technology is an environmentally benign hydrometallurgical process for extraction of base and precious metals from mixed oxides and sulphide ores. Glycine is the simplest amino acid which is available in bulk, an environmentally safe and stable reagent. It selectively extracts specific base and precious metal and leaves common gangue minerals intact in the residue. Glycine could be easily recovered and recycled which reduces the processing costs and reagent consumption.
In this study, the extraction of nickel with glycine from asbestos flotation tailing provided by Dumont Nickel Inc. has been studied. The extraction results from the flotation residue showed near complete recovery of nickel from heazlewoodite and awaruite minerals with the total recovery of 60%. The elemental analysis of leach liquor showed a high selectivity for nickel extraction against the major impurities of magnesium, silicon, iron, chromium, aluminium, manganese and calcium present in the tailings. The stability of glycine during the extraction has been analysed by a developed calorimetric and UV-vis methods. Based on these results, glycine was quite stable during the test and recovered after the nickel adsorption on the resin. The best kinetics of extraction was obtained by applying ammonia as a pH modifier at 45 ̊C and pH10. The incorporation of ammonia in extraction of nickel known as GlyAmmTM is added to improve the kinetics of extraction and the amount of metal in solution.
This testwork highlights the feasibility of nickel extraction in heap leach or tank leach for a more economical extraction using the Glycine Leaching Technology. The bottle roll and column leach tests have been performed at pH10 using NaOH as pH adjuster. The results showed a promising extraction of nickel from flotation residue containing heazlewoodite and awaruite minerals. The extracted nickel was recovered by adsorption onto ion exchange resin and the recycled glycine was used for the next round of extraction. This investigation has been done in collaboration with Mining and Process Solution (MPS) who own the patents to GlyLeachTM and GlyAmmTM processes.