الفهرس 
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Abstract
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A study was made on Egyptian phosphate rock of El Sebaiya area in order to concentrate it by the method of partial acidulation This method is based upon the solubilization of calcium carbonate impurity present in the phosphate rock, using dilute inorganic acids thus enriching the phosphate rock due to the decrease in the amount of the accompanying impurities. Careful control of the operating conditions were conducted in order to solubilize as much as possible of the calcium carbonate and leave the phosphate matrix least effected, ie.,the optimum conditions of partial acidulation where the highest degree of enrichment and highest recovery were obtained.
The acids used in the study were HCl and HNO 3’ In case of partial acidulation using HCl promising results were obtained and a degree of 25 % enrichment in the phosphate content of the rock was attained and the best conditions were 30 minutes and at a quantity of 60 % of the stoichiometric amount of the acid that is required to react with the calcium carbonate impurity. However there was no definite acid concentration at which better results were obtained.
In case of using HN03 good results were also obtained .The best conditions were 20 minutes ,as a time for partial acidulation and at a quantity equals 60 of the