Phosphoric Acid Production by the Electric Furnace Process

10 Phosphoric Acid Production by the Electric Furnace Process 

BC-11 Conveyors G-3 Roll compactor CR-4 Breaker SC-5 Screen X-7 Grate calciner H-8 Rotary kI In C-9 Fluorine scrubber E-10 Cooler 

H-12 Electric furnace, steel shell S-13 Electrostatic olust precipitator T-14 Phosphorus sump E-15 Phosphorus condenser 

One advantage of the furnace process is its ability to use low-grade phosphate rock provided that the principal impurity is silica. Iron oxide and alumina are much less objectionable in the furnace process than in the wet process. Siliceous phosphate rock containing about 24% P2O5 is used in several plants such rock may be obtained at a very low cost in some locations. Rock containing as much as 7% AI2O3 is acceptable. 

If lump or pebble rock of suitable size (about 0.6-4.0 cm) that is resistant to decrepitation on heating is available, the cost of agglomerating the charge may be avoided. However, such rock is selddrh available thef fore, the rock usually is agglomerated and calcined or sintered before charging it to the furnace. Carbon monoxide gas, which is a byproduct from the furnace, is the usual fuel for the calcination. Even so, this step is expensive. 

---