LECTURE 17-19 IIF PHOSPHORUS INDUSTRIES.pptx

PHOSPHORUS INDUSTRIES

1. IIF. PHOSPHORUS INDUSTRIES

2. Ca10(PO4)6F2- Fluorapatite Major products Phosphorus Phosphoric acid Ammonium phosphate Calcium phosphate Nitrophosphate Sodium phosphate Organic phosphate

3. Phosphorus content in phosphate rock is expressed as % P2O5 BPL-Ca3(PO4)2 High grade rock phosphate from Jhamarkotra contain +30% P2O5 rock phosphate from Jhabua and Chattarpur is used for the production of elemental phosphorus

4. PHOSPHORUS Pertinent Properties Mol. Wt. 123.9 M. P. 44.1oC B. P. 280oC Density Solid 1.82 Liquid 1.74 (45oC) Ignites spontaneously in air, must be stored under water.

5. Red Phosphorus (P4) Mol. wt. 123.9 M.P. 593oC Density of solid 2.36gm/cc Exist in at least six different crystal modifications. Formed by heating yellow phosphorus to give a higher degree of oxidation resistance and stability.

6. Consumption Pattern 18-20% of the phosphate rock --> elementary phosphorus. End Uses of Elemental phosphorus Phosphoric acid 90% Phosphorus oxychloride (POCl3) 3 Phosphorus trichloride (Pcl3) 3 P2O5, P4, 4

7. Methods of Production 2Ca3(PO4)2+10C+6SiO2 P4(yellow grade)+6CaSiO3+10CO 250-450oC P4 (yellow grade) P4 (red grade) Raw Materials Low grade, crushed phosphate rock, coke as reductant, and sand as flux

8. Quantitative Requirement Basis: 1 ton of yellow phosphorus (93%) Phosphate rock 7.5 tons at 32% P2O5 to 9.6 tons at 25% P2O5 Sand 3.3-3.8 tons Coke 1.6-1.8 tons Carbon electrode consumptions 18-25 kg Electricity 12000-15000KWH Cooling water 200-250 tons Plant Capacities: 25-70 tons/day of P/ furnance /plant

9. Major Engg. Problems Electric furnace design High voltage with large reaction zone desirable to reduce the electrode and transformer system for the same power point Exclusion of air is necessity where elemental phosphorus only to be produced. Control and Operation of furnace Changes in compositions or ratio of blending of raw materials markedly change. Safety in handling phosphorus Yellow phosphorus oxidizes vigorously, air contact must be avoided

10. H3PO4 MW 98 MP 42.4oC BP loses water of hydration (H3PO4)2. H2O at 213oC Density 1.83 gm /cc at 20oC

11. Consumption Pattern Fertilizers Soaps and detergents Food chemicals

12. Methods of Production Wet process Strong sulfuric acid leaching Hydrochloric acid leaching Electric Furnace Processes Direct conversion at plant site Oxidation and hydration of phosphorus Blast furnance - no longer competitive

13. Wet process (Strong sulfuric acid) Ca3(PO4)2+3H2SO4+6H2O → 2H3PO4 +3(CaSO4.2H2O) Side reactions CaF2+H2SO4+2H2O → 2HF+CaSO4.2H2O 6HF+SiO2 → H2SiF6+2H2O Raw Materials: High grade of imported ore is necessary to avoid solubilisation of mined rock impurities such as aluminium, silicon, iron, and alkali minerals. For low grade ore beneficiation process is used H2SO4

14. Major Engg. Problems Process design Fineness of grind- grinding costs and reactor fixed charges Temperature- must be kept 80oC Control of sulfuric acid- for pure product, the excess H2SO4 must be eliminated with a slower filtration rate. Materials of constructions Acid proof brick Air vent system Rubber lined steel storage tanks

15. Wet Process (Hydrochloric acid leaching) Ca3(PO4)2+6HCl+6H2O → 2H3PO4+3CaCl2 CaF2+2HCl → 2HF +CaCl2 6HF+SiO2 → H2SiF6+2H2O

16. Raw Materials Phosphate rock of high P2O5 HCl Gas or concentrated aqueous HCl Organic solvents C4 & C5 alcohol solvents are used to extract H3PO4 from CaCl2 solution

17. Quantitative Requirements Basis:1 ton of 100% H3PO4 in 98% yield Phosphate rock (32% P2O5) 2.3 tons HCl (100%) 1.4 tons Solvent make-up 3 kg ( Butanol or amyl alchol ) Flocculating agent 0.4 kg Plant Capacities: 15-150 tons/day of 100% H3PO4

18. Major Engg. Problems Solvent recovery: expensive solvent Materials of construction: HCl resistant materials Waste disposal: CaCl2 aqueous effluent and siliceous rock residue