Mining is a complex process. So, to help you understand more about what we do, here’s a glossary of commonly used mining terms.
Beneficiation plant – The plant at a mine site where phosphate rock is separated from the sand and clay components of the matrix. The plant consists of a washer which physically removes clay and separates pebble sized phosphate rock from the matrix. The remaining sand and granular phosphate rock moves to a flotation plant where a biodegradable oil is used to separate the fine phosphate rock particles from the remaining sand. The remaining sand is then pumped to reclamation sites.
Clay settling area – Clay settling areas are reservoirs built at the mine site to store phosphatic clay that has been separated from the matrix at the washer. State and local laws require clay settling area dams to be constructed to highly exact engineering standards. Clay slurry is pumped into one end of the reservoir. As the water travels across the reservoir, the clay settles to the bottom. Clear water is removed at the opposite end and returned to the mine site for reuse.
Dragline – A large crane-like earthmoving machine. Mining and initial reclamation require moving more materials than can be accomplished with standard excavation equipment. Draglines provide mining companies with the ability to efficiently move large quantities of material. A large-capacity bucket swings from cables on the end of the boom, scooping material that is then moved to adjacent areas. Draglines are electrically powered and run by two employees, an operator and an oiler. Dragline operators are typically some of the most experienced employees at a mine, often times with 20-30 years experience.
Ditch & berm – When mining is occurring measures must be taken to protect the areas adjacent to the mine property. Berms are constructed to ensure that muddy water does not leave the mine property and affect local waterways. Recharge ditches, on the outside of the berm, provide hydration to surrounding properties to ensure mining does not impact groundwater levels on the surrounding property.
Flotation – Phosphate rock can be physically separated from the matrix at sizes where the material is larger than sand. Flotation is used to separate finer phosphate particles from sand. A bio-degradable reagent, similar in consistency to vegetable oil, is introduced to a slurry of particulate phosphate rock and sand and the mix is then aerated. The reagent attaches to the phosphate particles, causing them to float to the surface with the air bubbles, where the material can be skimmed from the surface. To remove the remaining phosphate, the process is reversed and repeated with a reagent that attaches to the sand, which is then floated and removed. The sand removed in this process is then returned to the mine site to be used in reclamation. The reagent bio degrades in the mine water circulation system and is undetectable in the mine’s water supply.
Matrix – The phosphate ore that we mine from the ground is often referred to as matrix. This term comes from the fact that phosphate ore in Central Florida is made up of roughly equal parts of phosphate, sand and clay.
Mitigation – The dictionary defines mitigation as “to make less severe.” Regulators require mitigation from anyone applying for a permit to disturb wetlands. While the industry does reclaim the wetlands we disturb on a 1:1 basis, we are required to provide additional mitigation for the time those wetlands are out of service while being mined. Depending on the circumstances, mitigation may be done at the mine site, or at another site within the watershed and can take many different forms. Some examples include: construction of more wetland acreage to be reclaimed at the mine site than was originally present, placing permanent conservation easements over vital wetlands, off-site land conservation projects, off-site wetland or stream restoration projects or off-site wetland construction.
Mine cut – Surface mining is done in a zig-zag pattern. The dragline removes the overburden from above the matrix and casts it to the side. The dragline will mine in a line before turning to repeat the process. As the next line is mined, overburden is placed into the cut where the previous mining took place. After mining, the landscape is series of zig-zagged valleys referred to as mine-cuts. Once mining is complete in the section, sand removed in the flotation process is pumped back into the mine cuts and then excavators re-contour the land in accordance with the reclamation plan.
Outfall – All permitted mines must collect rainfall that falls within the mining operations to ensure turbid (muddy) water does not leave the property and affect the surrounding environment. During much of the year, mines collect excess water and must discharge it from the property. Excess water is discharged through controlled outfalls that are permitted through the state and federal governments. Water quality must be continually monitored to ensure that the discharged water meets state water quality requirements.
Overburden – The earthen material that lies above the phosphate deposit, which must be moved during the mining process. This layer can range from between 15-70 feet deep.
Permit – Permits are the guiding documents issued by regulators at the local, state and federal level that provide mining companies the ability to mine, but also lay out a broad range of conditions that must be met. Failure to meet the conditions of the permit results in enforcement action by the regulatory agency that issued the permit. Many modern permits require companies to demonstrate compliance before allowing them to move into the next permitted section of the mine. Applications for mining permits are incredibly complex and require volumes of data collection, environmental analyses and engineering studies to prove the feasibility of the mining and reclamation plans. The documentation supporting the permit application can often include hundreds of thousands of pages of data.
Phosphate rock – Phosphate rock is the finished product that goes from the mine to Mosaic’s fertilizer manufacturing plants. Through a separation process, it is removed from the matrix material that is mined by the draglines. Phosphate rock is not water soluble and is not useful as a nutrient until after it is processed at Mosaic’s manufacturing facilities.
Phosphatic clay – Phosphatic clay is a unique clay material present in the phosphate ore that is spongy in nature and has a high holding capacity for water. The spongy nature of the material makes it impractical for wide use in reclamation because of its instability. Instead, the clays are consolidated in clay settling areas. Once full, the clay settling areas are reclaimed for agricultural uses and make excellent pasture or row crop land.
Reclamation – The process by which mining companies return mined land to productive uses or natural landscapes. The phosphate industry is required to reclaim every acre we mine and wetlands are required to be reclaimed on an acre for acre, type for type basis. When regulators approve a mining permit, they also approve a reclamation plan. The reclamation plan details what the landscape will look like after reclamation is complete. The mine site is divided into smaller sections in the permitting process and reclamation is required, by law, to be in place within two years of mining operations being complete in each section. Since reclamation became mandatory in 1975, the science has continually developed and the phosphate industry has now successfully demonstrated proficiency in reclaiming all the habitats we’re permitted to disturb. To see examples of our reclamation, please visit the photo gallery.
Setback – Local, state and federal permits all carry separate requirements for setbacks. Setbacks are how far mining must be kept away from particular boundaries. The boundary may be related to county rights-of-way, private property or preservation areas. Setback distances will vary based upon individual circumstances or local ordinances.
Slurry – To transport matrix (see definition above) to the mine plant for separation, the material must be pumped. After being mined by the dragline, matrix is placed into a slurry pit, where a water gun is used to create a “slurry” of water and matrix that is about 30 percent solids. This slurry is then pumped through metal pipes to the plant where the phosphate rock can be separated.
Upland – Land that lies above where water collects or flows and is typically well drained. Upland habitats may include pasture, forests, prairies or scrub.
Washer – A common term for the plant at a mine where clay, sand and phosphate rock are physically separated.
Water recycling – Since the 1970s, the phosphate industry has worked hard to reduce water consumption. Modern mines include freshwater circulation systems that allow water to be reused and minimize the need for groundwater pumping. Water flows on a circuit between the mining sites, plant and clay settling areas. The clay settling areas also act as freshwater reservoirs so that a steady supply of water is available for the mining process. At Mosaic’s phosphate manufacturing facilities, approximately 90 percent of all water used is either recycled or reused.
Wetland – Land that has a wet or spongy soil and often times collects water. Wetland habitats may be forested, herbaceous or wet prairie.