Method for making an agglomerate of an ore by contacting the ore with an acid solution and a stucco binder.

Heap leaching is used to recover metals from low grade ores. As the leach solution percolates through the heap, the mineral is solubilized and retained in the leach solution. In addition to pulling solubilized minerals through the heap, the percolating leach solution also causes migration of fine particles. The migration of fines can clog the natural flow channels through the heap by forming impermeable barrier layers within the heap, protecting the underlying section of the heap from the percolating leach solution. When this happens, the protected sections are only partially leached, or not leached at all, which lowers the overall recovery of minerals from the ore.

Researchers at the University of Utah have developed a method for agglomerating ores by combining the ores with acid solution and stucco. By adding stucco along with an acid solution, high-quality agglomerates are formed that have a suitable water content and high permeability to fluid flow through a packed heap of agglomerates. The resulting agglomerates substantially decrease the migration of fines, while inhibiting the formation of barriers within the leached ore, resulting in higher rates of metal recovery and fewer leach solution transfer equipment blockages.

Proof of Concept

• Stucco does not need to be of architectural quality, alternative sources of stucco are also suitable such as used drywall or other materials.
• Formulations for high-quality agglomerates can be adjusted for the type and particle size distribution of the ore.
• Increases leaching yield and efficiency.

Jonathan Tyler
801-587-0515
jonathan.tyler@utah.edu