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FERTILIZER MANUFACTURE AND THE HAZARDS

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What is fertilizer?

Fertilizers are essential plant nutrients that are applied to a crop to achieveoptimal yield and quality.

Nutrients are classified into three sub-groups based on plant growth needs.These are:

Macro or primary nutrients: nitrogen (N), phosphorus (P),potassium (K)

Major or secondary nutrients: calcium (Ca), magnesium (Mg) andsulphur (S)

Micro nutrients or trace elements: chlorine (Cl), iron (Fe),manganese (Mn), boron (B), selenium (Se), zinc (Zn), copper (Cu),molybdenum (Mo) etc.

Nitrogen is the main driver of yield

Three main nutrients: Nitrogen, Phosphorus and Potassium

Nitrogen (N), the main constituent of proteins, is essential for growth anddevelopment in plants. Supply of nitrogen determines a plants growth,vigour, colour and yield.

Phosphorus (P) is vital for adequate root development and helps the plantresist drought. Phosphorus is also important for plant growth anddevelopment, such as the ripening of seed and fruit.

Potassium (K) is central to the translocation of photosynthates withinplants, and for high-yielding crops. Potassium helps improve crop

resistance to lodging, disease and drought.

In addition to the three primary nutrients, the secondary nutrients sulphur,magnesium and calcium are required for optimum crop growth. Calcium isparticularly important for the yield, quality and storage capacity of high-value crops such as fruit and vegetables.

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Among the major plant nutrients, nitrogen is most important forhigher crop yieldsNitrogen fertilizers are produced in many countries, reflecting the wideavailability of key raw materials - natural gas and air, needed for itsproduction on an industrial scale.

Nitrate is immediately and easily taken up by plantsAmmonia (NH3) is the basis for all nitrogen fertilizers and it contains thehighest amount of nitrogen (82%). Ammonia can be applied directly to thesoil, but for several reasons, including environmental, it is common tofurther process ammonia into, e.g., urea or nitrates before application. Ifammonia is applied directly to the soil, it will be converted to ammonium(NH4) and nitrate before plants can use it as a source of nitrogen.

While ammonium and nitrate are readily available to plants, urea first needsto be transformed to ammonium and then to nitrate.

Inorganic Nitrogen Fertilizers

Created through Haber-Bosch process Combine N2 and H2 under high temperature and pressure to create NH3gas

Anhydrous ammonia will boil & volatilize under normal atmosphericconditions Compression and refrigeration turn it to liquid Applied by injection into to soil to minimize losses into the air

N+3H 2NH

Production of Ammonium Nitrate

The processes involved in the production of ammonium nitrate in industry,although chemically simple, are technologically challenging. The acid-basereaction of AMMONIA with NITRIC ACID gives a solution of AMMONIUMNITRATE.

NH+HNONH4NO

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FEED-STOCK FOR AMMONIA

Natural Gas is the principal feed-stock for Ammonia Production. NaturalGas is classified as ASSOCIATED or NON-ASSOCIATED.

Associated gas occurs with crude oil: it is liberated from crude oil when thepressure is released from the oil-gas separator plant. Since methane is themost volatile, it can be released at relatively high pressure. By releasingsuccessively at lower pressures, a separation can be made in whichmethane is released first, ethane, butane and propane, are collectedseparately.The term Natural Gas is usually refers to the fraction that contains mostlyMETHANE with only small percentage of ethane and higher hydrocarbons.

For the use of Ammonia Feed-stock methane is preferable to the higherhydrocarbons, because all carbon in the feed-stock is converted to carbondioxide or monoxide, which must be removed from the ammonia synthesisgas.

HAZARDS OF AMMONIUM NITRATE

FLAMMABILITY=0 REACTIVITY=3

HEALTH=2 SPECIAL HAZARD-OXIDIZER

Ammonium nitrate has a melting point of 170C and decomposesabove 210C. It is not in itself combustible but, as it is an oxidizing agent, itcan assist other materials to burn, even if air is excluded.

Ammonium nitrate will not explode due to the friction and impact found in

normal handling, but it can be detonated under heat and confinement orsevere shock. For example, in a fire, pools of molten ammonium nitratemay be formed and if the molten mass becomes confined (e.g. in drains,pipes, plant or machinery) it could explode, particularly if it becomescontaminated.

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