THE MANUFACTURE OF ACID PHOSPHATE. 



15 



(4) Conversion of aluminum phosphate to aluminum sulphate and 



phosphoric acid : 



2 molecules 3 molecules 1 molecule 2 molecules 

 2A1P0 4 + 3H 2 S0 4 = A1 2 (S0 4 ) 3 + 2H 3 P0 2 

 Wt. 245 Wt. 294 Wt. 343 Wt. 196 



(5) Conversion of calcium carbonate to calcium sulphate, carbon 

 dioxide, and water: 



1 molecule 1 molecule 1 molecule 1 molecule 1 molecule 

 CaC0 3 + H 2 S0 4 = CaS0 4 + C0 2 + H 2 

 Wt. 100 Wt. 98 Wt. 136 Wt. 44 Wt. 18 



If 196 parts by weight of sulphuric acid are required to convert 

 310 parts of tricalcium phosphate into monocalcium or soluble phos- 

 phate, then 0.632 part of acid will be required for every 1 part of tri- 

 calcium phosphate. If we use ordinary "chamber acid" of 50° B. 

 strength which contains, according to the table on page 5, 62.18 

 per cent of sulphuric acid, 1.016 parts will be necessary for every 1 

 part of tricalcium phosphate. 



In Table III, modified from one prepared by Wyatt, 1 is given the 

 quantity of sulphuric acid of various strengths necessary to bring 

 about the reactions outlined above. 



Table III. — Weight of "chamber acid" of various strengths required to convert one 

 pound of each of the ingredients of phosphate rock into soluble compounds. 



Material acidulated — Ingredient. 



Tricalcium phosphate (CasCPO^z) 



Calcium fluoride (CaF 2 ) 



Iron phosphate (FePO<) 



Aluminum phosphate (A1P0<) 



Calcium carbonate ((CaC0 3 ) 



Quantity and strength of acid required. 



B. 49° B. 50° B. 51" B. 52° B. 53° B. 54° B. 55° B 



Lbs. 

 1.060 

 2.117 

 1.640 

 2.023 

 1.652 



Lbs. 

 1.040 

 2.067 

 1.601 

 1.975 

 1.613 



Lbs. 

 1.016 

 2.019 

 1.564 

 1.929 

 1.576 



Lbs. 

 0.992 

 1.972 

 1.528 

 1.885 

 1.539 



Lbs. 

 0.970 

 1.928 

 1.494 

 1.842 

 1.504 



Lbs. 

 0.948 

 1.885 

 1.460 

 1.801 

 1.471 



Lbs. 

 0.927 

 1.843 

 1.428 

 1.761 

 1.438 



Lbs. 



0.907 



1.803 



1.397 



1.723 



1.407 



Table IV gives the quantities of sulphuric acid of various strengths 

 required for every 100 pounds of the phosphate rock. 



Table IV.- — Quantities of "chamber acid" required (theoretically) to convert 100 pounds 

 of Florida hard rock phosphate into acid phosphate. 



Components of rock. 



Per cent. 



Strength and quantities of acid required 

 for 100 pounds of rock. 



48° B. 



50° B. 



52° B. 



54° B. 



Tricalcium phosphate (Ca 3 (P0<) 2 ) 



80.0 

 4.5 



Pounds. 



84.8 



9.5 



Pounds. 

 81.3 

 9.1 



Pounds. 

 77.6 

 8.7 



Pounds. 

 74.1 



Calcium fluoride, (CaF 2 ) 



8.3 



Iron phosphate, (FePO<) 





Aluminum phosphate, (A1P0<) 



6.0 



3.5 



5.5 



.5 



12.1 



5.8 



11.6 

 5.5 



11.1 

 5.3 



10.6 



Calcium carbonate, (CaC0 3 ) 



5.0 



Silica, (Si0 2 ) 





Moisture, (H 2 0) 





















Total 





112.2 



107.5 



102.7 



98.0 









1 Phosphates of America. 



