The fertilizer industry, vital for ensuring large-scale agricultural production, is also accountable for certain gaseous emissions. If not appropriately addressed, these can be harmful to the environment and human health.

Gas dedusting stands out as one of the most effective solutions to control and mitigate these emissions. In this piece, we’ll delve into the application of this process within fertilizer treatment plants.

Why is dedusting gas treatment?

Dedusting in gas treatment is the process of removing dust and solid particulate matter from exhaust gases. This process is crucial for several reasons:

dedusting gas treatment

Large quantities of dust in exhaust gases can lead to air pollution, which can harm the environment. Releasing dust-laden gases into the atmosphere can contribute to haze, reduce air quality, and result in adverse health effects for people and animals. By dedusting gases, emissions are controlled, and environmental standards are met.

Many governments and regulatory bodies around the world have set standards for emissions from industrial processes. To comply with these regulations and avoid penalties, industries must treat their exhaust gases to reduce particulate emissions. Dedusting ensures that these emissions remain below the set limits.

Accumulation of dust can lead to wear and tear on machinery and equipment. When dust accumulates on machine parts, it can cause friction, blockages, and reduce efficiency. By removing dust from the gases, you can increase the lifespan and efficiency of your equipment.

In industries where product purity is essential, even small amounts of dust or particulate matter can contaminate the final product, affecting its quality. Dedusting ensures that gases used in or around the production process do not introduce unwanted contaminants.

Certain types of dust can be explosive under the right conditions. By removing these dust particles, the risk of explosions is significantly reduced. Additionally, some types of dust are hazardous to human health when inhaled; hence, removing them protects workers and communities nearby.

Recovered dust can sometimes be recycled or sold, leading to additional revenue for industries. Furthermore, by ensuring equipment remains dust-free, maintenance expenses can decrease, and machinery downtimes are reduced.

In essence, dedusting in gas treatment is a critical process that ensures environmental protection, compliance with regulations, equipment longevity, product quality, safety, and potential economic benefits.

Dedusting gas treatment

Gas treatment on superphosphates

Phosphate-based fertilizer production, specifically TSP and SSP, is a meticulous process fundamental to the agricultural industry. This production starts with introducing phosphoric rock into a reactor. After this initial interaction, the resultant material is conveyed on the Kuhlmann belt, continuing the reaction process. The compound then heads to the granulator, culminating in a drying phase.

Throughout these four critical stages, gas emissions occur. The first two stages, in particular, showcase the most intense emission concentrations. These emissions arise from the phosphoric rock’s reaction with acids, typically H2SO4 or H3PO4. The reactions release F-based gases due to the rock’s fluorides. Gases like HF, SiF4, and F2 emerge, along with a significant dust amount and occasional gases like H2S and CH3SH.

Addressing these emissions requires implementing an efficient gas scrubbing system. This solution comprises two distinct phases:

  • Fluorine Derivatives and Dust Removal: The initial phase zeroes in on removing F derivatives and dust through a series of venturis-cyclones. The by products are H2SiF6 and SiO2. A key advantage of this process is the ability to reuse the H2SiF6 in the rock’s initial acid attack, reducing emissions and liquid effluent treatment. Rigorous pH control during this stage is vital to prevent crystallization issues that might clog the equipment.

  • Sulphur Derivative Neutralization: If sulphur derivatives are detected, a second phase is introduced. This stage entails these compounds’ neutralization via a chemical wash, utilizing NaOH and oxidizing agents, such as NaClO or KMnO4.

FERTILIZANTES 2 - Tecnium

This comprehensive gas scrubbing system ensures cleaner and more efficient superphosphate production, offering a sustainable and cost-effective solution for fertilizer plants.

Fertiberia MAP production 1 - Tecnium

Gas dedusting in Ammoniacal Fertilizers

The fertilizer industry leans towards creating compounds combining nitrogen, phosphorus, and potassium (N/P/K). These mixtures vary in proportions, contingent on their end-use and diverse manufacturing methods.

Among the range, ammonium phosphate-based fertilizers, like MAP and DAP, stand out. To meet market demands for these products, production plants have been established where phosphate rock undergoes digestion using HNO3, H2SO4, and/or H3PO4, supplemented with NH3 at specific stages.

Gas Emission Management

The primary gas emission sources stem from the reactor and granulator, with NH3, VOCs, and dust being the main contaminants. To manage these emissions, a three-phase strategy is employed: firstly, a venturi-cyclone system to remove dust; next, an acid wash tower to capture NH3; ands lastly, an alkaline process to treat any HF present.

In scenarios with high NH3 concentration in DAP, a recirculation technique with H3PO4 is employed to produce (NH4)3PO4. Upon crystallization, this compound can re-enter the production line as fertilizer.

Gas dedusting in complex fertilizers

Multi-component fertilizers are formulated with two or three of the fundamental elements: nitrogen, phosphorus, and potassium. They can also include additional nutrients and essential micronutrients.

The manufacture of these fertilizers involves a chemical reaction between their different raw materials. Next, the semi-fluid compound, known as slurry, undergoes processes of granulation, drying, classification, and conditioning. The type of nitrogen present in these fertilizers can vary (nitric, ammoniacal, or uric), depending on the raw materials used.

For the creation of NPK-type fertilizers, essentially two different infrastructures are used: plants that operate through the acid blend and those that use the nitro phosphate method.

Dust Elimination - Tecnium

Gas emission management and purification

The primary gaseous emissions originate in the granulator and dryer, releasing large volumes of dust with NH3 at elevated temperatures. Given this situation, TECNIUM proposes a recovery system that integrates a venturi and subsequently a multiventuri, ensuring high performance without risk of blockages.

This system not only achieves effective purification but also allows for the recovery and reuse of ammonium salts, such as ammonium phosphate, reducing waste and maximizing efficiency.

Our conclusions

Gas scrubbing is more than a technological solution. It’s an emblem of the fertilizer industry’s commitment to environmental sustainability, health, and welfare. By diligently deploying and maintaining these systems, the industry can continue its essential role in global agriculture without compromising environmental health and safety.

If you would like more information about our solutions for the dedusting treatment gases, please do not hesitate to contact our sales department. Filling in the form on this link with your details, we will be pleased to advise you!