EHS

Single super phosphate plant  latest design fluorine emission control system

With our latest emission free pollution control system we guarantee the pollution norms as per guideline of PCB.

Process reaction raking part for pollution..

CaF2+H2SO4            =               CaSO+2HF

4HF+ SiO2            =                  SiF4+H2O

3SiF4+2H2O           =                 2H2SiF6+ SiO2

The evolution of fluorine containing gases is a major problem in the SSP Production process. The arise from the fluoride and silicon contained as impurities in the rock.These elements combine with the water to form flurosilic acid (H2SiF6). Any excess silicon dissolves (in acid) to form silicic acid (SiO2-H2O). Typical rock phosphate contains about 8% Silica and 3% Fluorine by weight.

The temperature condition in the den causes a partial dissociation of fluorosilic acid, according to following chemical equation.

H2SiF6           =                  SiF4 + 2 HF

Both SiF4 and HF are gases at ambient temperature and pressure and collected by the Den & four stage scrubbing system. The fluoride evolution is 25% of the fluoride in the rock, increasing with increased sulphuric concentration. SiF4 hydrolyses to form Silica that potentially could present maintenance problem; within the scrubbing so simple void spray towers and pigtail nozzles are preferred, often with once through flow of scrubbing water.

Some of the highlights-

1. Separate seal tank for each scrubber.

2. Stirrer in seal tank for preventing settling of silica to avoid chocking of circulation pump.

3. Make up water controlled system .

4. Ideally continuous circulation of scrubber liquor from seal tank to venture through centrifugal pump.

5. Spray nozzle required size in each venture.

6. Id fan with proper pressure drop.

7. Silica separation system.