The progression of metallurgical testwor

The depletion of favourably located and higher-grade mineral deposits, paired with increased metal prices and higher capital costs, has triggered significant research into heap leaching of lower grade ores and wastes. This paper discusses the critical progression of metallurgical testwork essential for heap leach design, including processes for the bacterial heap leaching of low-grade ores and the acid heap leaching of uranium and nickel laterites. A comprehensive heap leach testwork program typically starts with bottle roll and column tests, moving on to pilot tests on heap samples to evaluate amenability to leaching based on ore properties such as porosity and permeability. Further phases focus on creating design criteria and utilising basic techno-economic models to estimate heap leach viability. Notably, Mintek has developed advanced in-heap monitoring systems and software to optimize operations. These innovations facilitate better decision-making regarding irrigation, aeration, and process adjustments in real-time, ultimately improving efficiency and recovery rates in heap leaching operations. The findings highlight the adaptability of heap leaching processes to a variety of ore types and the continued evolution of techniques to enhance recovery from challenging resources.