Steel & Mining Manager
The steel industry is currently facing a variety of challenges – sometimes one at a time, sometimes all at once. Controlling diffuse emissions falls into the latter category.
From raw material yards to sinter – and coke oven-plants, dust control has become a major objective and a powerful tool for reducing particulate matter (PM) emissions.
The reasons are manifold. Naturally, environmental responsibilities are a key driver, but they come hand-in-hand with creating a hazard-free workplace, complying with regulatory standards, achieving SDG targets for stakeholders, and simply maintaining good relations with neighboring communities around the steel mill.
While channeled emissions can be managed with well-established technologies such as dedusting devices and wet scrubbers, diffuse emissions pose a greater challenge due to their unpredictable nature. Yes – they are diffuse, and the factors influencing dust generation are numerous.
Three main areas typically come to mind when evaluating dust sources in a steel mill:
- Raw material yards
- Sinter plants
- Coke oven plants
Each of these areas share common pain points:
- Stockpiles
- Conveyor belt systems
- Unpaved roads
Stockpiles are a major source of dust emissions. Often located in windy areas like harbors, they present large surfaces vulnerable to erosion. This leads to dusty conditions in raw material yards and material loss, which can directly impact production costs.
To mitigate these effects, producers use aqueous solutions with crusting agents that are sprayed onto stockpiles, forming a solidified layer resistant to wind erosion.
So – easy fix? Only partially.
Raw material yards are busy environments. Stockpile management is an art in itself. Ships, trucks, or trains may arrive at any moment, unloading and forming new piles. Amid this constant activity, dust control must still be performed.
From a distance, a crust formed by conventional treatment is a barely visible. A practical solution is to use crusting agents in different colors – such as Ferrosolf® in white or green – allowing easy visual identification of treated piles, assessment of crust coverage, and planning of future treatments.
Unpaved roads are another dust source, especially with heavy machinery in use. Depending on meteorological conditions, either crust-forming agents or hygroscopic materials are applied. While crusts tend to break down over time, hygroscopic materials create a wetting effect that prevents dust formation. Kurita has advanced this approach by developing a product that combines crust formation and wetting effects, with an environmentally friendly footprint.
Conveyor belt systems present unique challenges, especially when transporting hot materials like sinter or coke. Two main dust control methods are used here: wet spray and foam-based systems.
Wet spray systems can be effective due to their cooling effect, but they also introduce moisture into the material. This moisture must be evaporated in subsequent processes (e.g., blast furnaces or coke ovens), resulting in a thermal penalty and increased total cost of ownership (TCO).
Foam systems, which deliver a relatively “dry” foam using compressed air and specialized nozzles, can achieve similar dust reduction while minimizing water usage – down to as little as 0.1% (1000 ppm). Foam units are ideal when the process or material cannot tolerate excess moisture, or when minimizing energy penalties is crucial. For this, Kurita uses its proprietary FFE® System, which features an automated unit for foam creation and dust control.
