| OCR Text |
Show COQUINA PLANT Cequina, or seashell, is an almost pure form of calcium carbonate. If line is required as a smelting flux, coquina can be used directly as recovered. However, when processed by burning, coquina is converted to calcium oxide or unslaked lime. Slaking, or mixing with water, results in an exothermic chemical reaction and produces calcium hydroxide, which is essential for alkalinity control in the ore railing flotation process. Vast beds of this coquina, deposited at some time in geologic history, are found along the seacoast south of Ilo, generally as a lightly salt- cemented conglomerate of sand, gravel, and shell. Process recovery of this material and operation of the Coquina Plant consists briefly of the following: Required quantities of strip-mined material are passed through a primary crusher to reduce the conglomerate to loose particles and small lumps which are then conveyed through a dry screening installation to remove the bulk of the sand and unrecoverable fines, and on to stock- pile. This dry-screened material is reclaimed from stockpile, passing through a 7'-0" diam x 16' long Marcy heavy duty scrubber to further reduce cementation and dissolve crystalline salt encrustnents, and into the heavy media separation unit, which floats off extraneous matter. The washed and separated coquina is belt-conveyed to a 100 ton overhead storage bin, truck hauled to the railroad loading dock, and rail-carried to the Smelter for burning. Sea water is used for scrubbing and separation processing, furnished by a deep well turbine pump rated at 1600 GPM against a 210' total head differential, operating in a well at the coastal plant site driven to 115 ft. below sea level. The plant can produce up to 40 tons of finished product per hour. Construction began in October 1958 with plant layout and site preparation work. Completed on December 15, 1958, a total of 45,000 CY were excavated. An additional 9,650 CI of structural excavation were required. The first of a total of 705 CI of structural concrete was poured in early December 1953, and the salt-water well was driven during the months |
