Abstract
A paradigm shift is underway in energy generation and consumption, and this will increase the demand for minerals, some of them critical, such as copper, nickel, and lithium, among others. Paradoxically, while the demand for these minerals is expected to increase, grades of mineral deposits are decreasing every day, and some of the deposits are located in areas of high social conflict with opaque governance structures that makes their exploitation difficult and problematic. This reality is creating the conditions for the mining industry, a historically conservative industry, to embark on the search for new, innovative and more efficient ways of processing minerals. New processes and technologies are required that, in addition to allowing economically viable extraction, allow better use of the natural resources and develop environmentally sustainable operations. One of these processes is HydroFloat® Coarse Particle Flotation (CPF), a process that, after being introduced in the fertilizer industry 20 years ago, has been successfully adopted for the processing of copper and lithium ores.
The HydroFloat is a fluidized-bed coarse particle flotation machine that overcomes buoyancy and froth recovery restrictions through up-current water velocity and plug flow conditions. This unit is comprised of an upper freeboard region, a central separation region and a lower dewatering cone. Classified and conditioned feed slurry is introduced to a feed-well within the upper freeboard region and settles against a rising mixture of water and fine air bubbles introduced and dispersed through a proprietary elutriation manifold with an external aeration system. Proprietary feed-wells and elutriation manifolds provide a uniform distribution of feed, fluidization water, and air across the HydroFloat cross-sectional area, maximizing throughput and process efficiency. Using this approach the HydroFloat CPF process can efficiently recover semi-liberated ore particles that are two to three times coarser than conventional flotation machines. This simple development allows tangible benefits which include higher recovery, improved tailing impoundment safety and reduced water, energy consumption and greenhouse gas emissions.
In this paper, we will present the results of a recent study conducted for a 100k tpd greenfield copper project. We have compared a conventional flow-sheet, representing the standard industrial approach, against a HydroFloat Coarse Gangue Rejection circuit. The Coarse Gangue Rejection (CGR) circuit has been recently commercialized by Anglo at their El Soldado plant in Chile. The CGR circuit allows a significant increase in the grinding end-point required for flotation, generating a coarse barren tail. This paper will provide a quantitative comparison of the conventional CGR flow-sheet, considering capital and operating costs, metallurgical efficiency, water recovery and tailing safety.
Additionally, the paper will discuss coarse particle flotation from a systems perspective, including the critical steps and unit operations, reliability and maintenance. This will include some insights on optimizing coarse particle flotation with grinding technology and classification technology platforms.