A Pilot-Scale Demonstration of the IMC/CLDRI/FIPR Flotation Process for Florida High-MgO Pebble
The beneficiation process developed by the China Lianyungang Design and Research Institute was proven by pilot plant tests on two samples of high-MgO reject pebble using either laboratory tap water or recycled process water from a local beneficiation plant. Key components of the process include fine grinding and inverse flotation to remove the liberated gangue minerals. For the pebble samples tested, flotation to remove dolomite was followed by flotation to remove silica. The pebble samples were washed to remove clays prior to grinding and flotation, but were not deslimed after grinding.
In addition to the collectors, phosphoric acid, sulfuric acid, soda ash, and diesel fuel were used as flotation reagents. The dolomite collector was proprietary fatty acid soap developed by CLDRI. The silica collector was an amine, currently used in the cleaner flotation step of the Crago Process.
For Pebble #1 the 30-ton pilot plant sample had a higher MgO content than the small sample used for laboratory development tests (3.5 vs. 3.1%). Consequently dolomite flotation was more difficult in the pilot plant and both grade and recovery suffered slightly. The opposite situation occurred for Pebble #2 (2.8 vs. 4.3%), and the pilot plant performance was improved over the laboratory. The CLDRI beneficiation process produced concentrates with MgO contents less than one-third the MgO contents of the pebble samples treated in the pilot plant. More than 75% of the phosphate contained in the pebble was recovered as concentrate analyzing 63 to 66% BPL.
A preliminary study was performed to develop estimates of capital cost and operating cost for a battery limits beneficiation plant employing the CLDRI beneficiation process. The study was based on a plant capacity of 300 tph pebble containing 54% BPL and 2.00% MgO and 200 tph concentrate containing 66% BPL and 0.82% MgO. The constructed cost of the battery limits beneficiation plant was estimated to be 32 million dollars. Operating costs were estimated at $15.62 per ton of concentrate.