The entirety of Mosaic’s mineral reserves and resources exist within sedimentary deposits. Economic phosphorite exists in a matrix of gravels, sands, silts and clays that are readily extractible. These economic deposits overlay a carbonate platform where phosphorite is absent. The bedrock and economic matrix are overlain by sands, clays and silts that are easily removed. Limitations of extraction arc the case of excavation, the capacity of the matrix to slurry, the grade of the phosphorite, gangue minerals, the depth of the matrix, and the overburden to be removed. Deposition of phosphorite occurred in the Miocene and Pliocene epochs. The depositional environment was shallow marine with sea levels of 300 ft. (100 m) or less. Cold phosphate rich waters were upwelled and mixed with warm surface waters creating vigorous biologic activity. Biological remains settled on the sea floor in regional anoxic zones. Phosphate subsequently substituted into calcium carbonate in the form of the mineral francolite. Accessory- mineralization does occur, but it is of little economic consequence. The deposit underwent transport and rework through marine winnowing. Post-depositional rework is extensive and site factors such as hydrology and groundwater geochemistry influence grade and gangue mineralization. Gangue minerals are generally limestone, dolomitic limestone, iron concretions of varying sizes and competent clays that resist disaggregation by washing. Limestone, dolomite and iron concr ........

Wingate is a phosphates production stage mining facility. Phosphate is extracted using surface mining techniques. Mining utilizes dredges to remove overburden and mine the phosphate ore (matrix). The matrix is hydraulically transported to the beneficiation plants via a series of centrifugal pumping systems.

Wingate has utilized two electric dredges, one to remove overburden and the other to mine phosphate matrix. Both dredges are equipped with cutter heads and slurry pumping systems to liberate and transport material. Spuds are used to position the dredges and allow a point by which to pivot. Cables extending from the dredges to anchors on the port and starboard sides enable swinging across the cut. Upon each pass, the dredges advance further into the cut. Periodically, the dredges will retreat and perform a "clean up" pass for additional overburden or matrix recovery.

Cut widths are dependent upon dredge geometry and overburden thickness. The water level of the dredge pond is nominally 15 ft.(4.6 m) below the ground surface. The overburden dredge utilizes a centrifugal pumping system with 26 inch (66 cm) steel pipe to transport and discharge spoil into previously mined areas of the pond. As the cutter head feeds the suction underwater, the solids arc diluted with an abundance of surrounding water. Slurry is transported at flows in excess of 20,000 US gpm. On occasion, dense, consolidated sand known as hardpan is encountered. As this material is tough to ........

- subscription is required.

- subscription is required.

- subscription is required.