SSP L FLOW CHART
PROCESS DESCRIPTION FOR S.S.P
The production of single phosphate (SSP) by a contribution process gives rise to particulars difficulties in that the reactant originally as thin slurry set to a solid mass during the reaction. The equipment that overcomes this problem is known as a “super phosphate den”. And more common designs are broad field den & max well den. The operating principals are essentially the same, with both producing solid super phosphate in a powder form by providing sufficient residence time for the SSP reaction to occur (complete matturing of the product may take up to 15 to 21 days after initial production.
CHEMISTRY OF SSP PRODICTION
Single super phosphate in made by the reaction of phosphate rock with sulphuric acid to connect the insolubic (tribe sic) form of calcium phosphate to a soluble (monobasic) form. This reason can be represented by the following chemical reaction, which is the major reaction.
1. Major reaction.
Ca3 (PO4) 2 + 2H2SO4 + H2O = CaH4 (PO4) 2. H2O + 2CaSO4
The calcium phosphate remains in the product and forms in the fertilizer. SSP contains about 14.50% of Phosphorous Pentaoxide (P2O5) equivalent.
The chemical impact of acid on phosphate rock librates a large amount of steam, which entrains fine particulates of phosphate rock and acidic gas and fumes, most of which originates from impurities in the rock
- 2. Minor reactions.
2CaO+2F2 = 2CaF2+ O2
3CaO + P2O5 = Ca3 (PO4) 2
CaO+SO3 = CaSO4
MgO+H2SO4 = MgSO4 +H2
Fe2O3+3H2SO4 = Fe2 (SO4) 3+3H2O
- 3. Pollution reaction.
CaF2+H2SO4 = CaSO4 +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 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. During the curing process t here are further fluoride losses, the amount depending upon reaction time in the Den.
The operation of a supper phosphate in Den, once the correct ratio of acid and rock has been established, is entirely automatic, and only the minimum amount of attention is needed.
The first unit operation in the SSP production is the Ball mill. In the ball mill the rock phosphate is crushed about 96% is passing through 100 mesh, which requirement of the process. Fine rock phosphate particles are collected through pulse jet collector of bags of rock grinding system, we have provided cyclone separator system attach with blower and pulse jet dust collector.
Dryer the rock phosphate containing moisture which dried up to 1 % through the co- current operation with hot air. The inlet temperature of the hot air is 300 deg. And outlet temperature is 60 deg. The diameter of the dryer is about 2.5 meter and length is about 15 meters. Only 10-15 % of the dryer volume solid material is filling for drying.
The name it self suggest the function of the equipment. In the pre mixer the rock phosphate, 98% H2SO4 acid and water are mixed to form slurry.
But we have to use H2SO4 acid about 67% concentrated for getting the better conversion of P2O5. The retention time is about 4 minute. The diameter and length of mixer depends on plant capacity.. This slurry is passes through the mixer to Den with the help of paddles.
Single Super Phosphate is one of the most popular and highly required fertilizer generally applied at the time of land preparation before sowing. Major constituents of this type of fertilizer is rock phosphate and sulphuric acid. We at Jobson fabricate, supply and install the components of Single Super Phosphate Plants and help developing the most cost-effective operational procedures to enhance the output.