Microwave Ore Pre-treatment Review and Process Flowsheet Conceptualization

Abstract

The global demand for mineral commodities has increased dramatically over the years, and this is largely due to several factors, including technological advancements, industrialization, and a rise in population. Further, the demand keeps increasing because the ore being mined is becoming more complex, and the feed grade is declining over the years, prompting the need for innovative technologies to treat such ores more efficiently. Microwave ore pre-treatment is one of the potential technologies that can be employed to improve process performance. This is possible because ores are composed of both good microwave heaters (e.g., sulphide minerals) and poor microwave heaters (mostly rock-forming minerals), which creates thermal stresses through rapid and differential heating when exposed to microwave fields. As a result, fractures are formed at the grain boundaries and through the matrix, potentially improving comminution and mineral accessibility to the leach solution. Also, because of their rapid and volumetric heating, microwaves can be employed for roasting pre treatment to oxidize sulphide minerals and natural carbonaceous materials encountered in modern gold ore deposits, making them amenable in conventional cyanidation processes after treatment. Following a thorough literature review of experimental and numerical studies to date, this article proposes several conceptual flowsheets incorporating a microwave ore pre-treatment system to improve the process performance of gold-copper ores in a crush-grind-flot-leach circuit. The literature review findings suggest that a microwave treatment system can be positioned in the comminution circuit to reduce the ore’s mechanical strength and enhance mineral liberation, potentially improving the milling and subsequent metal extraction processes (e.g., flotation and leaching). The technology can also be employed in the gravity circuit for chlorination roasting of gravity tailings to reduce the amount of gold recirculating in the grinding circuit. However, more studies should be conducted using the pilot scale continuous treatment systems to assess the technical and economic viability of the proposed flowsheets.