Abstract SYMPHOS 2011

70
FLUOROSILICIC ACID RECOVERY FROM PHOSPHORIC ACID PRODUCTION
Donal S. Tunks,
Jacobs Engineering S.A.,
Casablanca, MOROCCO
Because of environmental or economic factors, Fluorosilicic Acid (FSA) can be produced as a by-product of
Phosphoric Acid manufacture. FSA is present in wet process phosphoric acid, which is volatized when heated under
a reduced atmosphere as per the following reaction:
H2SiF6(l) → SiF4(g) + 2HF(g)
Some areas in the Phosphoric Acid Plant where FSA is volatized include the Reactor Flash Cooler and the Phosphoric
Acid Evaporator. This volatized FSA can be recovered with a small circulating spray in concentrations ranging from
13-26.5% H2SiF6 which can be sent for neutralization, sale, or for use as a raw material in the manufacture of value
added products.
This paper/presentation focuses on the scientific basis for FSA manufacture, various design approaches taken in the
past for such units, and options for FSA post-processing for the manufacture of value added products. From this
paper/presentation one would be given the tools to determine if FSA recovery is a viable option for their facility.
Iltifat Hussain,
Pakarab Fertilizers Limited,
Multan/PAKISTAN
PH-O-25
OPERATIONAL EXPERIENCE OF NITRO PHOSPHATE PLANT
PH-O-26
Pakarab Fertilizers Ltd. Multan, Pakistan came in existence in 1978 and this is the only company in Pakistan
producing Nitro Phosphate and Calcium Ammonium Nitrate till 2010. Plant is also producing Urea Fertilizer but in
small quantity. Total production volume is 0.8 Million Ton / Annum.
The company has special focus on environment that is the reason that CDM projects implemented on Nitric Acid
plant and Co. generation plant.
With reference to NP plant, Pakarab made a number of improvements in the original design of M/s Stamicarbon.
This project could not get through the guarantee tests even after the crystallization and refrigeration unit were
reinforced with additional equipments.
Rock Phosphate is the main raw material for NP production. Plant was designed on Jordan rock and later we have
tested rocks from Morocco, Egypt and Algeria. We have optimized the rock blending for smooth operation of plant.
Inert removing system was not smooth and frequent break down was common feature. PFL team changed the unit
with gravity settling tank battery and increased the on stream days.
The other bottle neck was CN separation centrifuges. Failure of this equipment kept the plant operation on low rate
hence these were replaced with Filter drums a slow moving unit. This helped to improved production quality and
service period.
Release of Ammonia from Neutralizers vent was environmental hazard. Installation of agitator improved the
situation.