US 5,211,735 AGranted

Process for preparing phosphated or nitrophosphated fertilizers through solubilization of phosphate rock

AssigneePetroleo Brasileiro S. A.

InventorsFabio G. M. Costa, Alberto C. C. Da Silva, Paulo C. W. De Albuquerque, Alberto Laranjeira

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Abstract

The invention aims at a process for preparing phosphated or nitrophosphated fertilizers through reaction of phosphate rock in aqueous pulp, with sulfuric and/or phosphoric acids, with addition, or not, of ammonia, so as to produce fertilizers of the types simple, double or triple superphosphates, nitrogen-bearing (or not) phosphated partially acidulated, and superphosphated ammoniated, the product being adequate for use as a fertilizer, either powdered or slurried. The invention allows for a more complete reaction due to the better contact between the liquid and solid reagents besides the complete utilization of the heat produced in the reaction as well as in the acid dilution in the aqueous medium, for the vaporization of the water present in the process.

Claims10

Dependent claims

A process for preparing phosphated or nitrophosphated fertilizer directly in a tubular reactor containing a reaction medium said process consisting essentially of the steps of:

(a) introducing phosphate rock as an aqueous pulp into said tubular reactor, wherein said aqueous pulp comprises between 60% and 80% by weight of said rock;
and
(b) introducing a stream of an acid selected from the group consisting of concentrated sulfuric acid, concentrated phosphoric acid, and a mixture thereof into said tubular reactor, wherein said pulp is mixed with said stream of acid and reacts throughout the length of said tubular reactor so as to produce said fertilizer directly, wherein the temperature within said tubular reactor is kept between 70.degree. C. and 150.degree. C. by ammonia addition or by water addition and wherein the pressure in said tubular reactor is controlled by means of the discharge area of the outlet nozzle of said reactor, so that the pressure is kept between 2 and 5 kgf/cm.sup.2 gauge.

Dependencies are inferred from the claim text.