The purpose of this second-year test program was to evaluate a previously selected flotation process for carbonate removal. The objectives were for the process to: utilize pond water, remove liberated carbonate materials prior to acidulation, and convert waste rock to reactor feed.
This project consisted of collecting and characterizing two pebble samples, one concentrate sample, and two pond water samples. These samples were subsequently used in laboratory experiments to set up the pilot plant testing. Pilot plant testing was done using low-grade pebble to determine the viability of the carbonate rejection process. Economic analyses were performed based on two different carbonate rejection flowsheets using this process.
This project demonstrated reduction in the CaO:P2O5 ratio and the minor element ratio (MER). Computations based on mesh by mesh data from the pilot testing demonstrated that low-grade pebble could be combined with concentrate and produce an acceptable product via the carbonate rejection process.
The economic analysis of this process indicated a moderately acceptable payout when low-grade pebble and concentrate were combined and the resulting blend was ground and floated. The life of the hypothetical reserve was extended by 24 percent.
Glenn A. Gruber et al., Jacobs Engineering Group, Inc. January 1999.