POTASSIUM INDUSTRIESPotassium, KPotassium Chloride, KClPotassium Carbonate, K2CO3

Potassium Sulfate, K2SO4

Potassium Hydroxide, KOHPotassium Dichromate, K2Cr2O7

Potassium Nitrate, KNO3

NITROGEN INDUSTRIESNitrogen, NNitric Acid, HNO3

Ammonia, NH3

Urea, NH2CONH2

Ammonium Nitrate, NH4NO3

Ammonium Sulfate, [NH4]2SO4

Ammonium Phosphate, NH4H2PO4

Potassiumi. occurs in nature only in the form of

its compounds/ mineralsii. the ten most common elements in

the earth’s crustiii. are obtained almost entirely by the

mining of salt depositsiv. was first isolated using an

electrolysis apparatus (1807)v. potassium superoxide (K2O)vi. potassium hydroxide (KOH)

Manufacturing Processes

A. Leaching-crystallization (1918) B. Flotation (1934)C. Electrostatic treatment (1974)

K salts

Carnallite Leach Tank Deslimator Hydroseparator

Separator

Treating Chamber

Fine KCl

Coarse KCl

Crushed Carnallite

Brine Amine/Starch

Flotation Cells

Importance and Uses.i. the activation of more than 80

enzymes.ii. also integral to a number of other

plant processes, translocation of carbohydrates, and protein synthesis

iii. it has important effects on quality factors of plants.

Economics

production is amounted to 25.8 x 106 t K2O in 2001

Potassium Chloride, KCli. occurs in many salt deposits mixed

with halite and other salt mineralsii. occurrs in natural sylviteiii. double salt carnallite

(KCl•MgCl2•6H2O)

Manufacturing and Production

A. Hot Leaching Process – An oldest industrial process used to produce potassium chloride from potash ore (1860)

a) Sylvinite Hot Leaching b) Hard Salt Leaching

Potash ore, ground to a fineness of <4–<5 mm, is stirred in a continuous dissolver with leaching brine heated to just below its boiling point.

Coarse fraction is removed from the dissolver and debrined.

Fine fraction (fine residue/ slime) is removed from the dissolver along with the crude solution, which is clarified with the aid of clarifying agents

6

Slime that separates is filtered off and then recycled to the recirculating brine. Clarification includes washing the residues with water to remove the adhering crude solution.

Hot, clarified crude solution is cooled by evaporation in vacuum equipment.

Potassium chloride and sodium chloride crystallize as the water is removed.

The crystals formed are separated from the mother liquor and processed further.

Mother liquor is heated.

Mother liquor is recycled to the dissolver as leaching brine.

Figure 2. Overall Systematic: Hot Leaching Process

Economics

More than 90% of the potassium chloride produced is used in single-nutrient or multi-nutrient fertilizers, either directly or after conversion to potassium sulfate.

Importance and Usesi. used for the manufacture of potassium

hydroxide and potassium metalii. medicine, in scientific applications, in

food processing, and as a sodium-free substitute for table salt (sodium chloride)

iii. third of a three-drug combination in lethal injection

iv. used (rarely) in fetal intracardiac injections in second- and third-trimester induced abortions

v. used as a fire extinguishing agent

Potassium Carbonate, K2CO3

produced in antiquity and used for many purposes

Manufacture and Production

i. the carbonation of electrolytically produced potassium hydroxide

ii. saturated with carbon dioxide; evaporated and the potassium carbonate hydrate (K2CO3•1.5H2O) precipitates out and is separated

iii. From Caustic Potash and Carbon Dioxide:

2KOH + CO2 → K2CO3 + H2O

Solid potassium carbonate is then obtained by crystallization (under vacuum and with cooling) from liquors or in the fluidized-bed process.

Until the hydrate K2CO3•1.5H2O finally precipitates in the crystallizer after cooling under vacuum.

The mother liquor is separated from the crystal suspension in hydrocyclones.

Mother liquor centrifuges.

Mother liquor is then filtered.

Mother liquor that is separated is fed back to the process.

The crystals are dried at ca. 110°C–120°C. Impurities such as soda, sulfate, silicic acid, and iron that concentrate in the mother liquors can be partially removed by removing a partial stream of the mother liquor or by drying process.

Crystals are calcined at 200°C–350°C to give 98%–100% K2CO3.

The resulting potassium carbonate is very pure and meets the requirements if the process is operated in appropriate manner.

Other processesi. Amine Processii. Nepheline Decomposition Process

The mineral nepheline is decomposed with limestone by sintering at 1300°C:

(Na, K)2•Al 2O3•2SiO2 + 4CaCO3 → (Na, K)2O•Al 2O3 +

2(2CaO•SiO2) + 4CO2

2(Na, K)AlO2 + CO2 + 3H2O → 2Al(OH)3 + (Na, K)2CO3

iii. The magnesia process (Engel – Precht process; limited interest):

3(MgCO3•3H2O) + 2KCl + CO2 → 2(MgCO3•KHCO3•4H2O) + MgCl2

iv. Le Blanc process:

K2SO4 + CaCO3 + 2C → CaS +K2CO3 + 2CO2

v. Formate process:

K2SO4 + Ca(OH)2 + 2CO → 2HCOOK + CaSO4

HCOOK + KOH+ 1.5O2 → K2CO3 + H2O

vi. Piesteritz process :

K2SO4 + 2CaCN2 + 2H2O → 2KHCN2 + CaSO4 + Ca(OH)2

2KHCN2 + 5H2O → K2CO3 + 4NH3 + CO2

vii. Ion-Exchange Process

Economicsi. About 4% to 5% of potash production is used in

industrial applicationsii. industrial grade potash was close to 1.35Mt K2Oiii. should contain at least 62% K2O and have very low

levels of Na. Mg, Ca, SO4 and Br

Uses.i. used for fertilizer, for production of commercial

soap, as a compound found in gunpowder and for making glass

ii. required for potassium silicate manufacture; used for many organic syntheses; electrical industry, the dye industry, the printing trade, the textile industry, the leather goods industry, and the ceramic industry

iii. uses potassium carbonate as a leavening agent in baked goods, as a debitterizing agent for cocoa beans, and as an additive for drying raisins

Potassium Sulfate (sulfate of potash), K2SO4

i. occasionally occurs in nature in the pure state in salt deposits but is more widely found in the form of mineral double salts in combination with sulfates of calcium, magnesium, and sodium

ii. mineral name is arcaniteiii. refined from naturally occurring mineral salt

deposits or by chemical synthesis

Manufacture and Production.

A. Industrial synthesis of potassium sulfate is a two-step process:

a) ionic separation of mined potassium chloride and another sulfate-bearing salt via electrolysis

b) joining of potassium ion and sulfate ion in controlled lab-setting at temperatures up to 120°C.

From Potassium Chloride and Sulfuric Acid (Mannheim Process)

The reaction of sulfuric acid with potassium chloride takes place in two stages:

1. KCl +H2SO4 → KHSO4 + HCl

2. KCl +KHSO4 → K2SO4 + HCl

i. Furnace, closed dish-shaped chamber with diameter up to 6 m, is heated externally. Potassium chloride and sulfuric acid are fed into the chamber in the required ratio at an overhead central point. The mixture reacts with evolution of heat and is mixed by a slowly moving stirrer fitted with stirring arms with scrapers. Potassium sulfate leaves the reaction chamber at this point and is neutralized and cooled. It normally contains 50 – 52% K2O and 1.5 – 2% Chloride. Hydrogen chloride gas formed when absorbed in water will form hydrochloric acid.

From Potassium Chloride and Kainite Kainite, KCl•MgSO4•2.75H2O is obtained from a grinned potash ore by flotation.

Kainite is converted into schoenite at 25°C with mother liquor containing the sulfates of potassium and magnesium.

Schoenite is filtered off and decomposed with water at 48°C.Most of the potassium sulfate to crystallize.

Sulfate mother liquor is recycled to the kainite–schoenite conversion stage.

Contains 30% of the potassium used, is treated with gypsum, CaSO4•2H2O

causing sparingly soluble syngenite, K2SO4•CaSO4•H2O, to precipitate.

Syngenite is decomposed with water at 5°C, which dissolves potassium sulfate and reprecipitates gypsum.

Potassium sulfate solution is recycled to the schoenite decomposition stage.

Gypsum is reused to precipitate syngenite.

Other Processes:From Potassium Chloride and Magnesium Sulfate

2KCl + 2MgSO4 + xH2O → K2SO4•MgSO4•6H2O + MgCl2 (aq)2KCl + K2SO4•MgSO4•6H2O + xH2O → 2K2SO4 + MgCl2 (aq)

From Potassium Chloride and Sodium Sulfate

4Na2SO4 + 6KCl → Na2SO4•3K2SO4 + 6NaClNa2SO4•3K2SO4 + 2KCl → 4K2SO4 + 2NaCl

From Potassium Chloride and Calcium Sulfate (processes based on gypsum, CaSO4•2H2O)

From Alunite, K2SO4•Al2(SO4)3•4Al(OH)3

Single-Stage Process from Sodium SulphateFor the sake of thermodynamics constraints, the process of potassium sulfate production from the sodium sulfate proceeds in two steps:

6KCl + 4Na2SO4 → 2K3Na(SO4)2 + 6NaCl2KCl + 2K3Na(SO4)2 → 4K2SO4 + 2NaCl

From Potassium Chloride and Langbeinite

K2SO4•2MgSO4 + 4KCl → 3K2SO4 + 2MgCl2

Economics

i. Worldwide, almost all technical grade potassium sulfate production, >99%, is used in agriculture.

ii. sulfate of potash production since the mid-80’s has been characterized by an up and down cycle.

iii. latest upward trend ended in 1998

Importance and Uses.

i. the most important potassium-containing fertilizer, being used mainly for special crops.

ii. constitutes 5% of the world demand for potash fertilizer and used in a wide range of industrial uses

iii. for manufacturing potassium alum, for manufacturing potassium carbonate and for manufacturing glass.

Potassium Hydroxide, KOH

i. called caustic potashii. caustic compound of

strong alkaline chemical dissolving readily in water, giving off much heat and forming a caustic solution

Manufacture and Production

A. Today, potassium hydroxide is manufactured almost exclusively by potassium chloride electrolysis. There are three different processes:

i. Diaphragm process ii. Mercury process iii. Membrane process

Economics

World production is estimated at 700–800 103 t/a

Usesi. used as a raw material for the chemical and

pharmaceutical industry, in dye synthesis, for photography as a developer alkali, and as an electrolyte in batteries and in the electrolysis of water

ii. raw material in the detergent and soap industryiii. as a starting material for inorganic and organic

potassium compounds and saltsiv. for the manufacture of cosmetics, glass, and textilesv. for desulfurizing crude oilvi. as a drying agentvii. as an absorbent for carbon dioxide and nitrogen

oxides from gases

Potassium Dichromate, K2Cr 2O7

i. major patent chromium chemical of commerce

ii. Germany introduced Na2CO3 as a substitute for K2CO3 in manufacturing, since then sodium dichromate gradually replaced K2Cr2O7

Manufacture and Production

A. Potassium dichromate process starts:

Resultant solids

mother liquor

mother liquor

Reactor

Filtration Crystallizer

*centrifugingCrO3

KOH

facility

crystals

1. Reaction of potassium hydroxide and chromium trioxide in a reactor creating a mother liquor:CrO + 2KOH → K2Cr2O7 + H2O

2. The mother liqour is filtered and the resultant filter solids are sent off-site for disposal to a facility.

The mother liquor is then sent to a crystallizer to precipitate crystalline K2Cr 2O7, which is recovered by centrifuging.

The resulting mother liquor from the product centrifuge is returned to the reactor.

It is also prepared from chromite ore (FeCr2O4). Chromite ore is

finely powdered and is heated with sodium carbonate in the presence of air in a reverberatory furnace. The reaction produces sodium chromate:

4FeCr2O4 + 8Na2CO3 + 7O2 → 8Na2CrO4 + 2Fe2O3 + 8CO2

Na2CrO4 + H2SO4 → Na2Cr2O7 + Na2SO4 + H2O

Na2Cr2O7 + KCl → K2Cr2O7 + 2NaCl

Usesi. Wide variety of uses in leather

tanning, dyeing, painting, porcelain decorating, printing, photography, pigment-prints, staining wood, pyrotechnics, safety matches, and for blending palm oil, wax and sponges

ii. for water-proofing fabrics, as an oxidizer in the manufacture of organic compounds, in electrical batteries, and as a corrosion inhibitor, and in oil refining.

Potassium Nitrate, KNO3

i. was first known by Hasan al-Rammah (Arab, 1270)

ii. niter-beds were prepared by mixing manure with mortar or wood ashes

iii. From 1903, fertilizer was produced on an industrial scale from nitric acid produced via the Birkeland–Eyde process.

iv. Haber process (1913) was combined with the Ostwald process after 1915, allowing Germany to produce nitric acid for the war.

Manufacture and Production

i. Almost all potassium nitrate, now used only as a fine chemical, is produced from basic potassium salts and nitric acid. Potassium nitrate can be made by combining ammonium nitrate and potassium hydroxide:

NH4NO3 (aq) + KOH (aq) → NH3 (g) + KNO3 (aq) + H2O (l)

without a by-product ammonia:

NH4NO3 (aq) + KCl (aq) → NH4Cl (aq) + KNO3 (aq)

from neutralization and the reaction is highly exothermic:

KOH (aq) + HNO3 → KNO3 (aq) + H2O (l)

Uses

i. most widely used application of the compound

ii. vital for growth of plantsiii. helps the crops to fully mature,

rather than delaying their growthiv. used as food preservatives during

the Middle Agesv. used in many processes like curing

meat, production of brine and making corned beef

vi. seventy five percent potassium nitrate is found in the "Chinese Snow" or " Devil's Distillate"

vii. also frequently used ingredient in cigarettes

Nitrogeni. nitrogen cycle represents one of the most important nutrient cycles found in terrestrial ecosystems

ii. used by living organisms to produce a number of complex organic molecules

iii. despite its abundance in the atmosphere, nitrogen is often the most limiting nutrient for plant growth

iv. two solid forms: ammonium ion (NH4

+) and the ion nitrate (NO3

-)

Manufacture and Production

i. form of ammonium can be absorbed onto the surfaces of clay particles in the soil

ii. ion of ammonium has a positive molecular charge is normally held by soil colloids

iii. micelle fixation (released from the colloids by way of cation exchange)

iv. most of the ammonium is often chemically altered by a specific type of autotrophic bacteria (genus Nitrosomonas) into nitrite (NO2

-); modification by another type of bacteria (genus Nitrobacter) converts the nitrite to nitrate (NO3

-) (Nitrification)

Economics

Scientists estimate that biological fixation globally adds approximately 140 million metric tons of nitrogen to ecosystems every year.

Importance and Uses

i. significant amounts enter the soil in rainfall or through the effects of lightning

ii. biochemically fixed within the soil by specialized micro-organisms like bacteria, actinomycetes, and cyanobacteria

Nitric Acid,

HNO3

i. strong, highly corrosive and toxic mineral acid and one of the most important inorganic acids

ii. one of the few substances capable of dissolving gold and platinum, which were known as the royal or noble metals

Manufacture and Production

Nitric Acid is produced in two methods:

i. Weak Nitric Acidii. High-strength Nitric Acid

A 1:9 ammonia/air mixture is oxidized at a temperature of 1380°F to 1470°F as it passes through a catalytic convertor:

4NH3 + 5O2 → 4NO + 6H2O; exothermic

reaction

Under these conditions the oxidation of ammonia to nitric oxide (NO)proceeds a range of 93 to 98 percent yield. Higher catalyst temperatures increase reaction selectivity toward NO production. Lower catalyst temperatures tend to be more selective toward less useful products: nitrogen (N2) and nitrous oxide (N2O).

The nitrogen dioxide/dimer mixture then passes through a waste heat boiler and a platinum filter.

The process stream is passed through a cooler/condenser and cooled to 100°F or less at pressures up to 116 psia. The nitric oxide reacts noncatalytically with residual oxygen to form nitrogen dioxide (NO2) and its liquid dimer, nitrogen tetroxide:

2NO + O2 → 2NO2 ↔ N2O4 A secondary air stream is introduced into the column to re-oxidize the NO that is formed in step 8. This air also removes NO2 from step 4.

The final step introduces the nitrogen dioxide/dimer mixture into an absorption process after being cooled. The mixture is pumped into the bottom of the absorption tower.

Air with liquid dinitrogen tetroxide is added at a higher point.

Deionized process water enters the top of the column.

•The absorption trays are usually sieve or bubble cap trays. The exothermic reaction occurs as follows:

3NO2 + H2O → 2HNO3 + NO

An aqueous solution of 55% to 65% (typically) nitric acid is withdrawn from the bottom of the tower. The acid concentration can vary from 30% to 70% nitric acid. The acid concentration depends upon the temperature, pressure, number of absorption stages, and concentration of nitrogen oxides entering the absorber.

The absorber tail gas (distillate) is sent to an entrainment separator for acid mist removal.

The tail gas is reheated in the ammonia oxidation heat exchanger to approximately 392°F.

The nitric acid formed in the absorber (bottoms) is usually sent to an external bleacher where air is used to remove (bleach) any dissolved oxides of nitrogen. The bleacher gases are then compressed and passed through the absorber.

The thermal energy produced in this turbine can be used to drive the compressor. Tail gases from the absorption tower are heated to ignition temperature, mixed with fuel (natural gas, hydrogen, propane, butane, naphtha, carbon monoxide, or ammonia) and passed over a catalyst bed.

Two seldom-used alternative control devices for absorber tailgas are molecular sieves and wet scrubbers. In the presence of the catalyst, the fuels are oxidized and the NOx are reduced to N2.

Economics

i. In 1991, there were approximately 65 nitric acid (HNO3) manufacturing plants in the U.S. with a total capacity of 11 million tons of HNO3 per year.

ii. The plants range in size from 6,000 tons to 700,000 tons per year.

iii. About 70 percent of the nitric acid produced is consumed as an intermediate in the manufacture of ammonium nitrate (NH4NO3).

Uses

i. another 5% to 10% produced is used for organic oxidation in adipic acid manufacturing

ii. also used in organic oxidation to manufacture terephthalic acid and other organic compounds

iii. explosive manufacturing utilizes nitric acid for organic nitrations

iv. its nitrations are used in producing nitrobenzene, dinitrotoluenes, and other chemical intermediates

v. other end uses of nitric acid are gold and silver separation, military munitions, steel and brass pickling, photoengraving, and acidulation of phosphate rock.

Ammonia, NH3

i. as the active product of “smelling salts,” the compound can quickly revive the faint of heart and light of head

ii. contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers

iii. either directly or indirectly, is also a building block for the synthesis of many pharmaceuticals

Natural gas

Desulfuriser

Steam reformer

Waste heat

boiler

Air reformer

steam

water

Air water

Waste heat

boiler

Shift converter

saturated UCARSOLCO 2 removal UCARSOL

CO 2 stripper

CO 2

Methanation water

Compression and cooling

Mixer

NH 3 converter

cool to 30°C

NH3

Decompression NH 3 recoveryimpurities

purge gas Ammonia

•Natural gas may contained sulfrous element or compound.•All sulfurous compounds must be removed from the natural gas to prevent catalyst poisoning. These are removed by heating the gas to 400°C and reacting it with zinc oxide:

ZnO + H2S → ZnS + H2O

•Primary reformer where superheated steam is fed with methane. The gas mixture heated with natural gas and purge gas to 770oC in the presence of a nickel catalyst:

CH4 + H2O ↔ 3H2 + COCH4 + 2H2O ↔ 4H2 + CO2

CO + H2O ↔ H2 + CO2

•Synthesis gas (cooled to 735°C) flows to the secondary reformer where it is mixed with calculated air:

CO + H2O ↔ CO2 + H2

O2 + 2CH4 ↔ 2CO + 4H2

O2 + CH4 ↔ CO2 + 2H2

2O2 + CH4 ↔ 2H2O + CO2

•Carbon monoxide is converted to carbon dioxide (which is used later in the synthesis of urea):

CO + H2O ↔ CO2 + H2

Achieved in two steps:•Gas stream is passed over a Cr/Fe3O4 catalyst at 360°C.•Gas stream is passed over a Cu/ZnO/Cr catalyst at 210°C.

•Water condenses out and is removed from 40°C.•Gas with carbon dioxide is passed through a stripper chamber and removal chamber to remove and to stripped carbon dioxide with UCARSOL. Carbon dioxide in the mixture dissolves.

•Saturated UCARSOL from carbon dioxide removal chamber is feed to carbon dioxide stripper to strip the remaining carbon dioxide for urea manufacturing.

•Remaining carbon dioxide is passed through the methanation chamber where water is produced and is removed by condensation at 40°C. Carbon dioxide is converted to methane using a Ni/Al2O3 catalyst at 325°C:

CO + 3H2 ↔ CH4 + H2OCO2 + 4H2 ↔ CH4 + 2H2O

•Gas mixture is cooled and compressed.

•Gas stream is mixed with the mixture of ammonia and unreacted gases and cooled to 5°C.•Ammonia is removed and is passed through decompression with another ammonia.

•Unreacted gases is heated to 400°C with P = 330 barg and passed over an iron catalyst and is converted to ammonia.

•Outlet gas is cooled from 220°C to 30°C. This process condenses more ammonia.•Ammonia after cooling is passed through decomposition with the ammonia from the step 11:

N2 + 3H2 ↔ 2NH3; P = 24 barg•Impurities such as methane and hydrogen become gases and are sent to the ammonia recovery unit. Purge gas (used for primary or steam reformer) and recovered ammonia are removed.

Economics

i. Annually 105 000 tonnes of pure ammonia (300 T day-1) are produced in Kapuni, and most of this is converted to urea

ii. produced in large petrochemical plants typically 400 000 tonnes to 800 000 tonnes per year and costing $150m to $250m

iii. produced in about 80 countries and 85 per cent is for nitrogen fertiliser production including about 6 per cent for direct use in agriculture

iv. production capacity has grown strongly – doubling from 62 million tonnes in 1974 to 130 million tonnes in 2000

Importance and Uses

i. used on site in the production of urea

ii. remainder is sold domestically for use in industrial refrigeration systems and other applications that require anhydrous ammonia

iii. an industrial chemical, but its most important use is as the building block of nitrogen fertilizers urea and ammonia chemicals

Urea, NH2CONH2

i. also called carbamide, is an organic chemical compound which essentially is the waste produced when the body metabolizes protein

ii. a compound not only produced by humans but also by many other mammals, as well as amphibians and some fish

iii. first natural compound to be synthesized artificially using inorganic compounds— a scientific breakthrough

Urea is produced from ammonia and carbon dioxide in two equilibrium reactions:

2NH3 + CO2 ↔ NH2COONH4 (ammonium carbamate)

NH2COONH4 ↔ NH2CONH2 (urea) + H2O

The urea manufacturing process is designed to maximize these reactions while inhibiting biuret formation:

2NH2CONH2 ↔ NH2CONHCONH2 (biuret) + NH3

Manufacture and Production

CO2

NH3

urea, excess NH3, carbamate, H2O

heat Decomposition

heat Concentration

Granulation

Synthesis

Recovery cooling

H2O H2O

NH3, CO2

urea, H2O

urea

•Carbon dioxide and ammonia is mixed in a reactor to form ammonium carbamate (exothermic reaction):

2NH3 + CO2 ↔ NH2COONH4 (ammonium carbamate); P = 240 barg

First reactor – achieves 78% conversion of carbon dioxide to urea

Second reactor – receives the gas from the first reactor and recycle solution from the

decomposition and concentration sections; 60% conversion of carbon dioxide to urea

at P = 50 barg.

•Water and unconsumed reactants (ammonia, carbon dioxide, ammonium carbamate) are removed ; pressure is reduced from 240 barg to 17 barg and the solution is heated:

NH2COONH4 ↔ 2NH3 + CO2 (decomposition of ammonium carbamate)

NH2CONH2 + H2O ↔ 2NH3 + CO2 (urea hydrolysis)

2NH2CONH2 ↔ NH2CONHCONH2 + NH3 (biuret formation)

Ammonia and carbon dioxide is passed through a recovery chamber. Unconsumed reactants are passed through the second reactor and purified excess ammonia is passed through the first reactor.

•Urea and water from the decomposition of ammonia carbamate is concentrated from 68% w/w to 80% w/w. Seventy percent of the urea solution is heated at 80°C-110°C under vacuum, which evaporates off some water. Molten urea is produced at 140°C; remaining 25% of the 68% w/w solution is processed under vacuum at 135°C.

•Urea that is 80% w/w is processed under granulation. Dry, cool granules classified using screens. Oversized granules are crushed and combined with undersized ones for use as seed. The final product is cooled in air, weighed and conveyed to bulk storage ready for sale.

Economicsi. Global production increased by 3.6% in 2009 to reach

146m tonnes, estimated the International Fertilizer Industry Association (IFA)

ii. currently 182 000 tonnes of granular urea are produced annually (530 T day-1); soon expected to increase to 274 000 tonnes

iii. world urea capacity will increase by 51m tonne/year between 2009 and 2014 to reach 222m tonne/year, a growth rate of 6%/year

iv. global demand for urea is forecast to grow at 3.8%/year to around 175m tonnes in 2014

v. much of the increase was from fertilizer demand while industrial applications for urea, accounting for 12% of total consumption, is expected to grow at 7%/year.

Usesi. used as a nitrogen-rich fertilizer, and as such is of great

importance in agricultureii. used as a component in the manufacture of resins for

timber processing and in yeast manufactureiii. used in the manufacture of urea-formaldehyde (UF)

resins produced by the condensation reaction between urea and formaldehyde

iv. a constituent of cattle feeds, and is a useful viscosity modifier for casein or starch-based paper coatings

v. small quantities are used as an intermediate in the manufacture of polyurethanes, pharmaceuticals, toothpaste, cosmetics, flame-proofing agents, sulphamic acid and fabric softeners

Ammonium Nitrate, NH4NO3

i. reacts with combustible and reducing materials as it is a strong oxidant

ii. prepared commercially by reaction of nitric acid and ammonia.

Manufacture and Production. Ammonium nitrate (NH4NO3) is produced by neutralizing nitric

acid (HNO3) with ammonia (NH3).

Ammonia and nitric acid are reacted in a solution formation chamber which is resulted a melt stream:

HNO3 + NH3 → NH4NO3

•As the melt stream is feed to a solution concentration chamber, an additive – magnesium nitrate or magnesium oxide – is injected. Purposes:

•to raise the crystalline transition temperature of the final solid product;•act as an desiccant, drawing water into the final product to reduce caking;•to allow solidification to occur at a low temperature by reducing the freezing point of molten ammonium nitrate.

Melt stream from step 2 is passed to solids formation chamber by prilling and by granulating.

Solid NH4NO3 is passed to solids

finishing chamber by drying and cooling.

Dried solids are processed again for screening. These solids vary in sizes and must be screened for consistently sized prills or granules. Offsize prills are dissolved and recycled to the solution concentration process.

Screened prills is processed for coating for bulk shipping and bagging.

Dried solids are processed again for screening. These solids vary in sizes and must be screened for consistently sized prills or granules. Offsize prills are dissolved and recycled to the solution concentration process.

EconomicsIn 1991, there were 58 U.S. ammonium nitrate plants located in 22 states producing about 8.2 million megagrams (Mg; 9 million tons) of ammonia nitrate.

Uses

i. Approximately 15% to 20% of this amount was used for explosives and the balance for fertilizers

ii. commercial grade contains about 34 percent nitrogen, all of which is in forms utilizable by plants

iii. it is the most common nitrogenous component of artificial fertilizers

iv. employed to modify the detonation rate of other explosives, such as nitroglycerin in the so-called ammonia dynamites, or as an oxidizing agent in the ammonals

v. also used in the treatment of titanium ores and in solid-fuel rocket propellants, in pyrotechnics

Ammonium Sulfate, [NH4]2SO4

Manufacture and Production. About 90% of ammonium sulfate is produced in three different processes:

1. caprolactam [(CH2)5COHN] by-product2. synthetic manufacture3. coke-oven by-product

Synthetic ammonium sulfate is produced by combining anhydrous ammonia and sulfuric acid in a reactor.

Coke-oven by-product ammonium sulfate is produced by reacting the ammonia recovered from coke-oven offgas with sulfuric acid.

Ammonium sulfate crystals are formed by circulating the ammonium sulfate liquor through a water evaporator, which thickens the solution.Ammonium sulfate crystals are separated from

the liquor in a centrifuge.

The crystals are fed to either a fluidized-bed or rotary drum dryer.

Dryers are continuously steam heated, while the rotary dryers are fired directly.

Rotary vacuum filters may be used in placed of a centrifuge and dryer.

Crystal layer is removed as product; not generally screened;carried by conveyors to bulk storage. Dryer exhaust gases pass through a particulate

collection device, wet scrubber.

After being dried, the ammonium sulfate crystals are screened into course and fine crystals.

Economics. In 1991, U.S. facilities produced about 2.7 million megagrams (Mg; 3 million tons) of ammonium sulfate in about 35 plants. Production rates at these plants range from 1.8Mg to 360Mg (2 tons to 400 tons) per year.

Uses. It is commonly used as fertilizer.

Ammonium Phosphate, NH4H2PO4

Manufature and Production. Two basic mixer designs are used by ammoniation-granulation plants: pugmill ammoniator and rotary drum ammoniator.

Phosphoric acid is mixed in an acid surge tank with 93% sulfuric acid and with recycled acid from wet scrubbers.

Mixed acids are then partially neutralized with liquid or gaseous anhydrous ammonia in a brick-lined acid reactor.A slurry of ammonium phosphate and 22%

water are produced and sent through steam-traced lines to the ammoniator-granulator.

Ammonia-rich offgases pass through a wet scrubber before exhausting to the atmosphere.

Granulation, by agglomeration and by coating particulate with slurry, takes place in the rotating drum and is completed in the dryer.

Primary scrubbers use raw materials mixed with acid.

Secondary scrubbers use raw materials mixed with pond water.

Moist ammonium phosphate granules are transferred to a rotary concurrent dryer.

Then transferred to a cooler.

Before being exhausted to the atmosphere, these offgases pass through cyclones and wet scrubbers.

Cooled granules pass to a double-deck screen, in which oversize and undersize particles are separated from product particles.

Oversized granules are crushed, mixed with undersized.They recycled back to the ammoniator-

granulator.

Economics. Total ammonium phosphate production in the U.S. in 1992 was estimated to b e 7.7 million megagrams (Mg; 8.5 million tons).

Uses.i.used as an ingredient in some fertilizers as a high source of elemental nitrogenii.used as a flame retardant in thermoplastic compositionsiii.analytically used as buffer solutions

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ZHANDERSOREÑO, reporting