الفهرس 
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Abstract
Normal superphosphate is manufactured locally by acid¬ulating ground rock phosphate with sulphuric acid. Egypt possesses large deposits of rock phosphate but limited quantities of sulphur. As a result of the rapid world wide rise in the demand fox’ sulphur and short supply in many areas, the delivery prices of sulphur for Egyptian fertilizer factories doubled about three times during the last few years.
It is therefore natural that Egyptian fertilizer manufactures should take a close look at processes that require less or no sulphur, the most attractive of which is known as nitrophosphates or nitric phosphate, in which rock phosphate is treated with nitric acid. The cost of this acid is likely to fall because of the availability of natural gas in Egypt and the technological improvements in converting ammonia to nitric acid. 171oreover, the nit¬rate ion supplies nutrient nitrogen and ends up in a pro¬duct, either with the phosphate or in a coproduct nitrogen fertilizer, whereas in sulphuric acid treatments, the sul¬phate ion serveo no useful purpose and the gypsum formed having very low nutrient value dilute the product.