Leaching metals from milled ores, concentrates, and especially tailings has become a significant business. Tailings reprocessing is particularly attractive due to its lower capital (CAPEX) and operating expenditures (OPEX), fast deployment, quick start of operations, and simplified permitting processes. Importantly, tailings often contain unrecovered metals, and extracting them not only adds revenue but also helps mitigate environmental, social, and governance (ESG) pressures, reducing the need for new mining activities. Mining companies are increasingly shifting from traditional smelting to hydrometallurgy to meet decarbonization goals and respond to investor, societal, and governmental demands for cleaner operations.
In leaching, both chemical and mechanical aspects must work synergistically to maximize metal recovery while minimizing costs. The chemical aspect involves the lixiviant formulation, type, concentration, physical conditions, pH, and other factors. Recent advances have predominantly focused on improving the chemical side. On the mechanical front, current processes such as in situ and heap leaching rely on passive lixiviant percolation through the ore. While tank leaching offers a more active approach, where particles are suspended in the lixiviant, the energy impact between grains is still relatively low. Choosing the optimal mechanical leaching process is a complex decision that involves multiple variables.
We have invented, developed (currently at TRL 3-4), and patented a new mechanical process for leaching metals from milled ores, concentrates, and tailings. This process, which we call Inverted Leaching, represents a novel approach. It is “inverted” because the lixiviant is injected from the bottom of the vessel, and due to liquefaction, it rises through the vibrating material, causing high-energy collisions between grains. This method enhances leaching efficiency and can be adapted to any metal or material using the chemical protocols already in place at the mining or refining site.
In traditional in situ leaching, studies show that 10–40% of the target metal often remains unextracted due to inadequate lixiviant distribution, ore heterogeneity, or mineral passivation—where reaction products form protective layers around metal particles. Our inverted leaching technology addresses these inefficiencies with several key advantages over heap and tank leaching:
- Lower lixiviant volume per kilogram of solid: Liquefaction occurs in a narrow range of moisture content (15–30% by weight).
- Complete processing in a single loading: The material is extracted, washed, decontaminated (if needed), pH-neutralized, and discharged in a dry, stackable form—eliminating the need for a separate dewatering step.
- Gas capture: Any gases produced during the process are captured, minimizing emissions.
Scalability is straightforward: capacity increases by adding more units. For example, if one complete cycle (loading, extraction, washing, decontamination, neutralization) takes 30 minutes, a 100-ton batch system could process up to 4,800 tons per day. The equipment’s footprint is just 16 m², with a height of 6 meters.
We are seeking partnerships with mining and refining companies to develop a pilot plant for this innovative mechanical leaching process.
(wrote by author, improved by AI)
