VEOLIA WATER NORTH AMERICA OPERATING SERVICES; LLC
发明人:
ASTLEY, Vaughn, V.,MICHALSKI, Dennis, H.,COOK, Robert
申请号：
USUS2011/062136
公开号：
WO2012/071565A3
申请日:
2011.11.23
申请国别(地区):
WO
年份:
2013
代理人:
摘要：
A process for the treatment of phosphoric acid plant pond water where an increased recovery of phosphorus values from the input pond water is achieved through the dilution of the initial pond water with clarified water from the product generation stage and/or the final stage clarified water. The waters and phosphate products contain the phosphate moiety, PO4 and this phosphate content can be analytically expressed as PO4, P2O5 or P. More importantly, the recycle of the product generation stage and/or final stage waters to dilute the feed pond water mitigates or eliminates the problems of silica gel formation and precipitation that occur when undiluted pond waters are processed. The formation of silica precipitate, contaminate the product Phosphate, diluting its phosphorus content and rendering separation difficult due to the silicas gelatinous nature. In addition, the dilution reduces phosphate losses in the first liming or neutralization stage rejected solids thereby increasing the yield of Di-Calcium Phosphate or ammonium magnesium phosphate or potassium magnesium phosphates. Yields can be further enhanced through the recycle of final stage sludge to recover the otherwise lost phosphorus values as a Di-Calcium Phosphate or other phosphate products. In certain aspects of the process, solids from a later stage neutralization and separation are recycled into the clarified liquid stream from an initial clarification and neutralization stage. A sufficient amount of solids are added to the clarified liquid stream to effect a pH-dependent precipitation of a DiCal phosphate product. In alternative aspects, an intermediate pH-dependent precipitation of a phosphate product is achieved through the addition of a neutralizing agent. The Di-Calcium phosphate product is further characterized by a low concentration of fluoride such that it can be used as an animal feed nutrient supplement. In addition, the phosphate product can be further processed to a high purity technical or f
