LEC 5: Fertilizer Industry

• Nitrogen (N)

• Phosphorus (P2O5)

• Potassium (K2O)

What are the three major plant nutrients and their chemical form?

Fertilizer

Any material added to soil or plant systems to supply nutrients needed for plant growth

Inorganic/mineral fertilizers

chemically processed or mined materials such as urea, ammonium sulfate, DAP, MOP, and NPK grades

Organic fertilizers

compost, manure, plant residues, and bio-organic products

Biofertilizers

products containing beneficial microorganisms that assist nutrient availability

industrial manufacture of mineral fertilizers (NPK)

What is the main focus of the fertilizer industry in CPI?

Best Available Techniques Reference Document

What does BREF mean?

Raw mats → chemical conversion → unit ops → product finishing → QC → uses → econ and envi control

What is the sequence of the fertilizer industry process?

natural gas+air+steam → ammonia → urea or NH4 salts → granules → bagged fertilizer → crop application

What is an example of fertilizer production process?

• fillers

• conditioning agents

• secondary nutrients

• moisture

• inert components

What are the other materials aside from the NPK, in an NPK-grade fertilizer?

Urea

Fertilizer high in nitrogen with grade 46-0-0

Ammonium Sulfate

Fertilizer with nitrogen and sulfur and grade 21-0-0-24S

Diammonium Phosphate (DAP)

Fertilizer with nitrogen and high phosphate with grade 18-46-0, also happens to be the world’s most widely used phosphorus fertilizer

Monoammonium Phosphate (MAP)

Fertilizer with nitrogen and high phosphate with grade 11-52-0

Muriate of Potash (KCl)

Fertilizer high in potassium with grade 0-0-60

Complete Fertilizer

A fertilizer with balanced NPK of 14-14-14

Ammonium Phosphate

Fertilizer with N and P as well but lower grade than DAP and MAP (16-20-0)

NPK Compound fertilizers

Fertilizer with multiple nutrients and various NPK grades

• Particle size distribution

• Moisture content

• Hygroscopicity

• Bulk density

• Granule hardness

• Solubility

• Compatibility

What are the important physical properties in the processing of fertilizers

Particle size distribution

Fertilizer physical property that deals with granule uniformity.
Too fine → dusting

Too coarse → uneven field application

Moisture content

Too much moisture causes caking, poor flow, microbial degradation in organic ferts, and reduced storage stability.

Hygroscopicity

Fertilizer physical property that deals with the absorption of moisture from air. Hygroscopic materials can cake during storage.

Bulk Density

Fertilizer physical property that affects bagging, transport, blending, storage bin design, and fertilizer spreader calibration.

Granule hardness

Weak granules break during handling and produce dust.

Solubility

Highly soluble fertilizers release nutrients quickly but may have higher leaching risk if poorly managed.

Compatibility

Some ferts cant be safely or practically mixed because they may react, absorb moisture, or form lumps.

• Nutrient concentration

• Acid-forming or alkaline effect

• Chemical stability

• Reactivity

• Corrosivity

What are the important chemical properties in fertilizer design?

Nutrient concentration

Higher nutrient concentration reduces transport and storage cost per unit nutrient. Example:
Urea contains 46% N, making it more concentrated than ammonium sulfate at about 21% N.

Acid-forming or alkaline effect

Fertilizer chemical property that deals with the tendency to acidify soil. Ammonium-based ferts tend to do this after nitrification. Some phosphate fertilizers can cause localized pH changes near the granule.

Chemical stability

Fertilizer chemical property that deals with stability during storage, transport, and application.

Reactivity

Acids, ammonia, phosphate rock, and nitric acid are reactive materials. Their reactions must be controlled for safety and product quality.

Corrosivity

Fertilizer plants often handle corrosive acids such as sulfuric acid, phosphoric acid, and nitric acid. Proper materials of construction are critical.

Nitrogen

The source of this raw mat includes air, natural gas or hydrogen source, ammonia, nitric acid, sulfuric acid, CO2

Phosphorus

The source of this raw mat includes phosphate rock, sulfuric acid, phosphoric acid, ammonia

Potassium

The source of this raw mat includes potash materials, especially KCl

Sulfur

The source of this raw mat includes sulfur, sulfuric acid, ammonium sulfate, gypsum-containing products

Micronutrients

The source of this raw mat includes zinc sulfate, borates, copper salts, iron salts, manganese salts, molybdates

ammonia, phosphoric acid

BREF states that most N ferts are derived from ____, and P ferts are derived from _____.

Haber - Bosch

A process of producing ammonia through nitrogen and hydrogen reactions.

Desulfurization of natural gas → Steam reforming → Shift conversion → CO2 removal → Methanation or purification → Ammonia synthesis

What are the steps of the Haber-Bosch Process?

Urea production

This production occurs through ammonium carbamate formation followed by dehydration.

Ammonium sulfate production

This production supplies both nitrogen and sufur. It is useful in sulfur-deficient soils but has lower N concentration than urea.

2NH3 + Sulfuric Acid → (NH4)2SO4

Ammonium nitrate production

This product of this chemical process is highly soluble and concentrated, but it requires strict safety control because it is an oxidizing material and can present explosion hazards under certain conditions.
NH3 + HNO3 → NH4NO3

Dust control

Phosphate rocks used in phosphate fertilizer processing is mined and processed through many unit operations and processes. Thus, _____ is important during phosphate rock grinding.

Phosphogypsum

This is the product when phosphate rock reacts with sulfuric acid to produce phosphoric acid and calcium sulfate by-product. The proccess is called wet-process phosphoric acid.

Single superphosphate (SSP)

This phosphorus fert contains available phosphate and gypsum. It is less concentrated than DAP or TSP but supplies sulfur and calcium.

Triple superphosphate (TSP)

This P fert is more concentrated than SSP because phosphoric acid is used instead of sulfuric acid as the main acidulating agent.

mined potash salts

Potassium fertilizer processing are often produced from ____.

Potassium.

What nutrient is good for overall plant health and stress tolerance. It’s also essential for root development, water regulation, fruit quality, disease resistance, and crop stress tolerance.

NPK compound fertilzier production general process flow

Raw mat storage → weighing → mixing → reaction/neutralization → granulation → drying → screening → cooling → coating → bagging

Nitrogen

This nutrient’s main function includes leaf growth, protein formation, chlorophyll production

Phosphorus

This nutrient’s main function includes root growth, energy transfer, flowering, seed formation

Potassium

This nutrient’s main function includes water regulation, disease resistance, fruit quality, stress tolerance

Sulfur

This nutrient’s main function includes protein synthesis and enzyme function

Calcium

This nutrient’s main function includes call wall strength

Magnesium

This nutrient’s main function includes central atom in chlorophyll

Hydrogen production from fossil feedstock generates CO2.

Why is ammonia production energy-intensive?

• Nutrient runoff and eutrophication

• Nitrate leaching

• Ammonia volatilization

• Nitrous oxide emission

• Soil acidification

• Salinity and chloride concerns

What are the environmental impacts during fertilizer use?

Dust from grinding/granulation

What environmental issue does this engg control solve:

bag filters, cyclones, wet scrubbers

Ammonia emission

What environmental issue does this engg control solve:
acid scrubbers, closed-loop recovery

NOx/N2O

What environmental issue does this engg control solve:
catalyst optimization, SCR, N2O decomposition

SO2/SO3 mist

What environmental issue does this engg control solve:
double-contact sulfuric acid process, mist eliminators

Fluoride emissions

What environmental issue does this engg control solve:
wet scrubbers, fluorine recovery

Acidic wastewater

What environmental issue does this engg control solve:
neutralization, sedimentation, filtration

Phosphogypsum

What environmental issue does this engg control solve:
lined storage, water recycling, monitoring

Off-spec product

What environmental issue does this engg control solve:
recycle to granulator when safe and feasible

• Right source

• Right rate

• Right time

• Right place

What are the Rs in the 4R nutrient stewardship?