Learn how urea is made in industries using ammonia and carbon dioxide. Understand the step-by-step urea manufacturing process, from raw materials to prills and granules.

Urea is one of those everyday substances that quietly keeps the world running—especially in agriculture. Whether you’re a farmer, a student, or just curious, understanding how urea is made can give you a new appreciation for what goes into producing food and keeping industries moving.

Let’s walk through the urea manufacturing process step by step, in simple language.

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What Is Urea?

Urea—also called carbamide—is a white, solid compound that’s rich in nitrogen, a key nutrient for plants. It dissolves easily in water, doesn’t leave behind salty residues, and is often shaped into tiny round pellets or granules for easier use.

Fun fact: your own body produces urea naturally to get rid of extra nitrogen. That same compound, when made in factories, helps crops grow all over the world.

The story of synthetic urea goes back to 1828, when chemist Friedrich Wöhler accidentally created it in a lab. It was the first time a compound found in the body was made using inorganic materials—an important moment in science.

What’s Used to Make Urea?

You don’t need a long list of ingredients to make urea—just two:

Ammonia (NH₃)
Carbon dioxide (CO₂)

These two are actually quite common in large-scale industrial plants. In fact, most urea is made within ammonia plants, where CO₂ is often a leftover byproduct. Instead of wasting it, companies use it smartly to produce urea.

The Main Chemical Reactions Behind Urea

Making urea is basically a two-step chemical process:

Ammonia + Carbon dioxide → Ammonium Carbamate
Ammonium Carbamate → Urea + Water

The first step releases heat, while the second one needs heat to get going. Both steps are reversible, which means not everything turns into urea on the first try. That’s where recycling comes in (more on that below).

Inside the Reactor: Where the Urea Manufacturing Process Happens

The heart of the operation is the reactor, where ammonia and CO₂ are pumped in under high pressure (around 14 MPa) and at a temperature of 170–190°C. The first reaction happens here, and it gives off a lot of heat, which is reused in other parts of the plant to save energy.

After that, the mixture moves into a decomposer, where the second reaction takes place. This part absorbs heat, so extra energy is needed to keep things moving.

If the temperature goes too high, a compound called biuret can form. Too much biuret (over 2%) is harmful to plants and animals, so engineers constantly monitor the temperature to keep it just right.

Recycling: Nothing Goes to Waste

Not all the ammonia and carbon dioxide react the first time. In fact, only about half of it becomes urea in one pass. But the unreacted parts are not wasted—they’re captured and sent back through the system, which boosts overall efficiency to over 99%. It’s a smart way to save resources and reduce environmental impact.

Purification & Concentration

Once urea is formed, it’s not quite ready yet. The mixture still contains water and leftover gases. These are removed in distillation towers and evaporators.

Distillation separates leftover ammonia and CO₂.
Evaporation concentrates the urea into a thicker liquid.

It’s important to control the temperature here. If it’s too low, crystals will form inside the equipment. If it’s too high, urea quality can suffer.

Turning Liquid Urea into Solid Granules

The final step is shaping the urea. The hot, liquid urea is sprayed through nozzles in a prilling tower, where cool air blows from the bottom. As the urea droplets fall, they cool and harden into small round pellets, also called prills. These are then collected, packed, and sent out for use.

Where Is Urea Used?

Urea is used in a lot more places than you might think:

1. Agriculture (Fertilizer Use)

Primary use of urea is as a nitrogen fertilizer for crops.
Contains 46% nitrogen, making it the most concentrated solid nitrogen fertilizer available.
Promotes healthy plant growth, improves crop yield, and boosts chlorophyll production.
Can be applied directly to soil or as a foliar spray (mixed with water and sprayed on leaves).
Commonly used for rice, wheat, corn, sugarcane, and other staple crops.
Suitable for all soil types and climates due to its high solubility and quick absorption.

2. Chemical Industry (Raw Material for Products)

Used to manufacture urea-formaldehyde resins, which are common in adhesives and plastics.
A key ingredient in melamine and other industrial chemicals.
Helps produce coatings, sealants, and some types of rubber and foam products.
Used in water treatment chemicals and specialty resins for various industrial applications.

3. Automotive Industry (DEF – Diesel Exhaust Fluid)

Urea is a critical component in Diesel Exhaust Fluid (DEF), also known by brands like AdBlue.
DEF helps reduce harmful NOx emissions in diesel engines by converting them to harmless nitrogen and water.
This is essential for vehicles meeting Euro 6 and BS-VI emission standards.
Widely used in trucks, buses, and some diesel cars.

4. Laboratory & Medical Applications

Used in laboratories for preparing urea solutions in biochemical and molecular biology experiments.
Acts as a protein denaturant in lab settings.
Used in some dermatology products for skin care and moisturizers, especially in treating dry or rough skin conditions.
Urea-based ointments are used in cracked heels, eczema, and psoriasis treatment.

5. Animal Feed Industry (Feed Additive)

Technical-grade urea is sometimes added to ruminant animal feed (like cattle) as a non-protein nitrogen source.
Helps stimulate microbial activity in the stomach to better digest low-quality feed.
Must be carefully balanced to avoid toxicity.

6. Building & Construction Materials

Used in urea-formaldehyde foams and resins, commonly applied as insulating foam in buildings.
Forms part of plywood adhesives and laminated board glues used in furniture manufacturing.

7. Textile & Dye Industry

Used in textile printing to improve dye absorption and fix color on fabric.
Plays a role in treating textiles before or after dyeing for better finish and colorfastness.

Also read more on: Top Urea Manufacturers in the world

Step-by-Step Urea Manufacturing Process

Urea is made in factories using ammonia (NH₃) and carbon dioxide (CO₂). It’s a very important fertilizer because it contains a high amount of nitrogen, which plants need to grow. The production of urea happens in several steps, each involving careful control of temperature and pressure to get the best results.

Step 1: Synthesis – Making Ammonium Carbamate

The process starts with mixing compressed carbon dioxide and ammonia at a very high pressure (around 240 bar). These two chemicals react to form ammonium carbamate. This reaction gives off heat (it’s exothermic), and that heat is captured and reused in other parts of the plant.

The mixture goes into a reactor.
In the first reactor, about 78% of carbon dioxide gets converted to urea.
The rest of the gas is passed into a second reactor, along with recycled solution from other parts of the system.
Here, around 60% conversion happens at a lower pressure (about 50 bar).

The liquid coming out of these reactors is then sent for purification.

Urea Manufacturing Process step by step Explained How Urea Is Made in Industries

This diagram shows the step-by-step process of urea manufacturing, starting from synthesis with ammonia and carbon dioxide to final granulation for fertilizer use.

Step 2: Purification – Removing Impurities

At this stage, the mixture still contains unreacted ammonia, carbon dioxide, water, and ammonium carbamate. These need to be removed.

This is done in three stages:

The pressure is dropped from 240 to 17 bar, and the solution is heated. This breaks ammonium carbamate back into ammonia and CO₂.
Pressure is further reduced to 2 bar, and again to -0.35 bar.
With each drop in pressure, more unwanted gases are removed.

By the end of this step, most impurities are gone, and you’re left with a clean urea solution. Any unreacted chemicals are recycled back into the system.

Step 3: Concentration – Getting Rid of Extra Water

Now the urea solution needs to be concentrated, because it still contains a lot of water. This is done in vacuum evaporators:

The solution is heated slowly from 80°C to 110°C.
Water starts to evaporate, increasing the urea concentration from 68% to 80%.
Any urea crystals that formed are re-dissolved during heating.
Around 75% of the solution is handled this way.

The remaining 25% is processed under vacuum at about 135°C in a special two-stage system. At the end of this step, we get molten urea (a thick liquid form), which is almost pure.

Step 4: Granulation – Making Urea Solid Granules

Molten urea is now turned into small round particles, called granules or prills, which are easy to store and transport.

Here’s how it happens:

Molten urea is sprayed onto seed granules (tiny starter particles) inside a granulator.
These seed granules are kept in place using a bed of air.
As molten urea hits them, they grow in size.
At the other end, cool dry air helps harden the granules.

Then:

Granules are passed through screens to separate oversized and undersized particles.
Oversized ones are crushed and mixed with smaller ones to be reused.
Air and dust from the process go through dust scrubbers (filters) and get cleaned.
The final urea granules are weighed, cooled, and stored—ready to be sold.

A Word About Biuret

As mentioned earlier, biuret is a byproduct that can appear if things get too hot. It’s important for manufacturers to keep its level low—especially if the urea will be used on young plants or as a foliar spray. Too much biuret can damage seeds, roots, or leaves.

During urea production, if the temperature gets too high, a compound called biuret can form. This is bad for plants, especially young ones, because it can burn their leaves.

That’s why urea factories always try to keep biuret levels low, usually below 2%.

That’s why constant monitoring and precise temperature control are critical parts of the process.

The entire process is highly efficient. Almost all the unreacted ammonia and CO₂ are recycled, which means very little is wasted. Engineers continuously monitor and adjust conditions to get the best conversion rate and the purest product.

Final Thoughts

The urea manufacturing process is a mix of science, engineering, and smart resource use. It turns two simple gases—ammonia and carbon dioxide—into one of the world’s most important agricultural tools.

What’s impressive is how the process reuses materials, saves energy, and minimizes waste, all while producing something that helps feed billions of people. So the next time you see a bag of urea fertiliser, remember the incredible journey behind those tiny white granules.

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