Production of food grade phosphoric acid

Claim 1

A METHOD OF PRODUCING FOOD GRADE PHOSPHORIC ACID FROM IMPURE PHOSPHATE ROCK CONTAINING MORE THAN ABOUT 0.5% IRON, WHICH COMPRISES: LEACHING THE IMPURE PHOSPHATE ROCK WITH ABOUT TWICE ITS WEIGHT OF A 20% PHOSPHORIC ACID AT AN ELEVATED TEMPERATURE BETWEEN ABOUT 50* C9 AND 95*C. AND FOR A TIME SUFFICIENT TO REMOVE BY SOLUTION, THE MAJOR PORTION OF THE LMETALLIC IMPURITIES SOLUBLE IN SAID PHOSPHORIC ACID; SEPARATING THE RESULTANT PRODUCT INTO A SOLID PORTION AND LIQUID PORTION; DILUTING THE LIQUID PORTION WITH WATER; BOILING THE WATER-DILUTED LIQUID PORTION TO PRECIPITATE THE METALLIC IMPURITIES DISSOLVED THEREIN; SEPARAING THE PRECIPITATE FROM THE ACCOMPANYING LIQUID; AND RETURINING THE SAID LIQUID TO THE LEACH ING LIQUID IN A REPETITION OF THE PROCESS; WASHING THE FILTER CAKE WITH WATER UNTIL THE WASHINGS ARE IRON-FREE DENNING THE FULTER CAKE WITH SULPHURIC ACID TO PRODUCE A MIXTURE CONTAINING CALCIUM SULFATE AND PHOSPHORIC ACID; EXTRACTING THE PHOSPHORIC ACID FROM THE MIXTURE SO FORMED BY MEANS OF AN ORGANIC EXTRACTION AGENT, SELECTED FROM THE GROUP OF WATER IMMISCIBLE OXYGENATED HYDROCARBONS AND CONSISTING OF ALCOHOLS, KETONES AND ALDEHYDES HAVING AT LEAST THRE AND NOT MORE THAN EIGHT CARBON ATOMS IN THE CHAIN CARRYING THE OXYGEN GROUP; AND EXTRACTING THE PHOSPHORIC ACID FROM THE PHOSPHORIC ACID CONTAINING ING ORGANIC EXTRACTION LIQUID BY CONTACTING SAID LIQUID WITH WATER, TO PRODUCE AN AQUEOUS SOLUTION OF FOOD GRADE PHOSPHORIC ACID AND A SOLUTION OF THE ORGANIC EXTRACTION AGENT, AND RECOVERING THE SOLUTION OF FOOD GRADE PHOSPHORIC ACID PRODUCT.

Claim 2

A METHOD OF PRODUCING FOOD GRADE PHOSPHORIC ACID FROM IMPURE PHOSPHATE ROCK CONTAINING MORE THAN ABOUT 0.5% IRON, WHICH COMPRISES: LEACHING THE IMPURE PHOSPHATE ROCK WITH ABOUT TWICE ITS WEIGHT OF A 20% PHOSPHORIC ACID AT AN ELEVATED TEMPERATURE BETWEEN ABOUT 50* C9 AND 95*C. AND FOR A TIME SUFFICIENT TO REMOVE BY SOLUTION, THE MAJOR PORTION OF THE LMETALLIC IMPURITIES SOLUBLE IN SAID PHOSPHORIC ACID; SEPARATING THE RESULTANT PRODUCT INTO A SOLID PORTION AND LIQUID PORTION; DILUTING THE LIQUID PORTION WITH WATER; BOILING THE WATER-DILUTED LIQUID PORTION TO PRECIPITATE THE METALLIC IMPURITIES DISSOLVED THEREIN; SEPARAING THE PRECIPITATE FROM THE ACCOMPANYING LIQUID; AND RETURINING THE SAID LIQUID TO THE LEACH ING LIQUID IN A REPETITION OF THE PROCESS; WASHING THE FILTER CAKE WITH WATER UNTIL THE WASHINGS ARE IRON-FREE DENNING THE FULTER CAKE WITH SULPHURIC ACID TO PRODUCE A MIXTURE CONTAINING CALCIUM SULFATE AND PHOSPHORIC ACID; EXTRACTING THE PHOSPHORIC ACID FROM THE MIXTURE SO FORMED BY MEANS OF AN ORGANIC EXTRACTION AGENT, SELECTED FROM THE GROUP OF WATER IMMISCIBLE OXYGENATED HYDROCARBONS AND CONSISTING OF ALCOHOLS, KETONES AND ALDEHYDES HAVING AT LEAST THRE AND NOT MORE THAN EIGHT CARBON ATOMS IN THE CHAIN CARRYING THE OXYGEN GROUP; AND EXTRACTING THE PHOSPHORIC ACID FROM THE PHOSPHORIC ACID CONTAINING ING ORGANIC EXTRACTION LIQUID BY CONTACTING SAID LIQUID WITH WATER, TO PRODUCE AN AQUEOUS SOLUTION OF FOOD GRADE PHOSPHORIC ACID AND A SOLUTION OF THE ORGANIC EXTRACTION AGENT, AND RECOVERING THE SOLUTION OF FOOD GRADE PHOSPHORIC ACID PRODUCT.