How is the HPS mine different?
The HPS mine will be very different from traditional Florida phosphate mines with respect to its water use and how it handles clays. Most traditional phosphate mining operations use a wet “slurry” process to transport and separate phosphate from its naturally occurring matrix form. This process requires the addition of large amounts of water to the phosphate matrix and results in a leftover water/clay “slurry” after the phosphate is separated from the matrix. This water/clay slurry is typically placed into a “settling pond” to dry and consolidate over time. These ponds are often used for disposal as long as possible during a mining operation in order to minimize the acreage needed for waste clay disposal. As a result, these ponds typically remain in use throughout the entire life of a mining operation and are only reclaimed several years after all mining is completed.
Because the HPS families plan to continue agricultural operations on the land that is not being actively mined, they recognized early on that it would be important to return the mined areas back to productive use much quicker than the traditional timeframe (and without the need for clay settling ponds). As farmers, the families were also keenly interested in reducing the amount of water needed to mine. With these dual goals in mind, HPS invested in a research project, along with the Florida Industrial Phosphate Research Institute, to develop and refine reclamation techniques that allow the clays to be more beneficially used, rather than treated as waste. The result of this research project is an innovative new process that uses dry material transport, less water, and a mixing technique that quickly settles out water from the clays, eliminating the need for slurry pipelines and clay settling ponds, and allowing for rapid reclamation of mined areas.
The new transport, processing, and reclamation techniques have many advantages. First, the HPS process will require less water than traditional mining operations because the phosphate matrix will be transported dry to the beneficiation plant via a conveyor belt, rather than being mixed with water and pumped to the plant. Second, the waste clays will be mixed with sand and overburden, and this mix will be immediately available as backfill material for filling the mine cuts, eliminating the need for clay settling ponds. HPS also has committed to an aggressive backfill schedule, such that reclamation will occur almost immediately after each individual block is mined, minimizing the duration of mining and returning the land to its agricultural character more quickly. Finally, without areas of the land needed for long-term clay disposal, the post-reclamation uses of the site can be more flexible. Studies have shown the sand/clay/overburden mix will act like the existing soils, both in terms of nutrient value, stability, and permeability. In fact, independent tests of this soil mix by the University of Florida Institute of Food and Agricultural Sciences have shown its value for growing crops and other vegetation.
These innovative new processes—proven by pilot testing conducted as part of the research project—will allow for rapid reclamation immediately following mining activities. Rapid reclamation will allow the HPS families to continue the beneficial uses of the land as they have for decades.
In the coming days and weeks, please return to this space for further details on HPS’s proposed phosphate mining plan.