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Process Description



Fertilizers industry is a form of secondary chemical production. It is necessary to understand the inputs and processing techniques in order to identify the pollution sources and abatement measures in this industry.


Fertilizers may be categorized into two groups, natural and synthetic fertilizers. Synthetic fertilizers include different types accordingto their chemical composition, physical status and solubility in water. According to their chemical composition, fertilizers are categorized into three main groups as follows:
• Phosphatic fertilizers containing phosphorous as a base element, which is expressed by P2O5 %.
• Nitrogen fertilizers containing nitrogen as a base element, which is expressed by N2 %.
• Potassiumfertilizers containing potassium as a base element, which is expressed by K2O %.


In addition to the straight fertilizers containing single nutrient (N or P or K) there are the complex fertilizers containing two or three major plant nutrient N.P.K. Enormous varieties of NPK according to their contents of nutrients are available. Liquid fertilizers are also produced worldwide including hundreds offorms containing one or more nutrients together with trace elements. NPK fertilizers are produced in the Egyptian Fertilizer Development Center Pilot Plant, located in Talkha, in limited quantities according to the clients requests. Also in Delta Company there is a plant that produces urea- ammonium nitrate liquid fertilizer (32 % N).


The liquid fertilizers must be free of solids toavoid clogging the slurry nozzles. Concentrated phosphoric acid is used as the basis for high analysis liquids. When reacted with ammonia, it gives neutral solution which does not crystallize at low temperature. If ammoniated under pressure, ammonium polyphosphate forms. This can be stored and shipped as a solid and dissolved readily when needed. Another liquid fertilizer is anhydrous ammonia,vaporized to a gas and ploughed directly into the soil. A combination of solution/ suspension containing 13 % nitrogen and 43 % P2O5 has been developed, to which custom blenders can add potash and trace elements if needed.



1 Raw Materials, Chemicals and Other Inputs




1 Main Raw Materials

Inputs for the fertilizers industry vary according to the fertilizer type.Phosphate rock is considered the main raw material for the production of phosphate type fertilizers, while in case of nitrogenous fertilizers, ammonia is considered the main raw material. Ammonia is produced by synthesis of nitrogen and hydrogen. The latter is generated either by steam reforming of natural gas, or electrolysis of water. On the other hand, nitrogen is produced either from airliquification as in KIMA- Aswan, or combustion of natural gas.


Large quantities of acids are also used, namely sulphuric acid, nitric acid and phosphoric acid. In all fertilizers plants those acids are produced on-site. Raw sulphur is considered the main raw material for the production of sulphuric acid, whereas phosphoric acid production depends on phosphate rock as raw material. The productionof nitric acid is based on the on-site produced ammonia.


The involved catalysts in the fertilizers industry are as follows:
• In ammonia production:
– CoO, MoO3 and ZnO for sulphur removal.
– NiO for primary and secondary reformers.
– Iron oxide and chromium for CO high shift conversion and copper oxide and zinc oxide for low shift.– NiO catalyst for methanation.
– Iron promoted catalyst for ammonia synthesis.
• In nitric acid production: platinum/ rhodium catalyst.
• In sulphuric acid production: vanadium pentoxide catalyst.
These catalysts are usually not considered as inputs, instead they are considered part of the equipments. This is related to nature of the reactors in...