Improved Hard Process Description

  • IHP_Process_FlowThe process leverages the heat provided through the oxidation of carbon in petroleum coke  (which is already present as a reducing agent) and the heat integration characteristics of a rotary kiln to eliminate over 90% of the electricity consumed in the Furnace Acid Process.
  • The endothermic reduction and exothermic oxidation of phosphorus occur in a single vessel (ported rotary kiln). The key raw material, phosphate rock, can be much lower quality than required by WAP, with a minimum P2O5 concentration of about 15% and much less stringent criteria for impurities.
  • This phosphate rock is combined with green petroleum coke, sand (silica) and clay to make a 3/8 inch diameter ball using conventional grinding, drying and balling equipment.
  • The balls are fed into the ported rotary kiln, where phosphorus is reduced out of the ball and then oxidized to make P4O10 gas.
  • The P4O10 gas is cooled and absorbed in water in a standard acid hydrator, producing clean 70% concentration phosphoric acid (e.g. SPA).
  • The phosphoric acid can be sold to the fertilizer, animal feed or industrial markets.  The spent balls, comprising mostly hard calcium silicate, are cooled and sold for use as a construction aggregate: J-ŸRox

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KPA White Paper

History, Development, Status and Opportunities for Kiln Phosphoric Acid