Production of phosphates from alkali-processes phosphate rock
OwnerThomas Griffithinventor
Life of this patent
Estimating the term…
Abstract
Process for production of desired phosphates from naturally occurring phosphates is characterized by treating naturally occurring phosphates under alkaline conditions to produce a material comprising trisodium and/or tripotassium orthophosphates, carbonating said material in solution, and recovering the desired phosphates from the carbonated solution. The desired phosphates include di- and mono-sodium orthophosphate; pentasodium tripolyphosphate; sodium metaphosphate and its polymers; tetrasodium pyrophosphate; ammonium phosphate; sodium ammonium hydrogen phosphate, magnesium ammonium phosphate; and the corresponding potassium salts thereof.
Claims15
Process for production of desired phosphates from orthophosphates, comprising the steps of
- (a) treating naturally-occuring unsintered phosphate rock containing calcium, iron, and aluminium phosphates in such amount that the total content of iron and aluminium, calculated as Fe.sub.2 O.sub.3 and Al.sub.2 O.sub.3 respectively, is greater than 5% by weight of said material, under alkaline conditions to produce a reaction mixture comprising sodium and/or potassium orthophosphates;
- (b) separating solid orthophosphates from the reaction mixture;
- (c) dissolving the solid orthophosphates in alkali metal carbonate solution,
- (d) carbonating the resulting solution with carbon dioxide, and
- (e) recovering the desired phosphates from the carbonate solution.
A process for producing desired phosphate from naturally-occurring unsintered phosphate rock containing calcium, iron, and aluminium phosphate in such amount that the total content of iron and aluminium, calculated as Fe.sub.2 O.sub.3 and Al.sub.2 O.sub.3 respectively, is greater than 5% by weight of said material, the phosphates being selected from the group consisting of di- and mono- sodium phosphate, pentasodium tripolyphosphate, sodium metaphosphate, tetrasodium pyrophosphate, sodium hydrogen phosphate, ammonium phosphate, and magnesium ammonium phosphate, the processing comprising:
- (a) treating phosphate rock with alkaline solution to produce tisodium orthophosphate,
- (b) separating solid trisodium orthophosphate from the alkaline solution,
- (c) dissolving the trisodium orthophosphate in an aqueous solution,
- (d) treating the solution with carbon dioxide to produce disodium orthophosphate, and
- (e) recovering the desired phosphates.
A process for producing mono- and disodium orthophosphates and mono- and dipotassium orthophosphates from naturally-occurring unsintered phosphate rock containing calcium, iron, and aluminium phosphates in such amount that the total content of iron and aluminium, calculated as Fe.sub.2 O.sub.3 and Al.sub.2 O.sub.3 respectively, is greater than 5% by weight of said material, comprising the steps of:
- (a) treating the phosphate rock under alkaline conditions to produce trialkali orthophosphate from the treated rock,
- (b) dissolving the trialkali orthophosphate in an aqueous solution,
- (c) treating the solution with carbon dioxide to produce dialkali orthophosphate,
- (d) further treating the solution with carbon dioxide to produce a mixture of mono- and dialkali orthophosphates, and
- (e) crystallizing to recover the mono- and dialkali orthophosphate.
Dependencies are inferred from the claim text.