Suppressing Dust in Hoppers for Heavy Applications

Dust management during dry granular bulk materials handling is a complex process. Dust control solutions must be flexible to ensure effective dust collection for different applications. Sometimes, with unusual materials and certain project requirements, controlling airborne dust becomes a real challenge.

An interesting example is an approach to mitigating dust emissions during processing of silicon metal, a unique product that is lumpy and abrasive. It is a hard and brittle crystalline solid that is used to manufacture steel, solar cells, and microchips. It naturally occurs in silicate minerals, including silica, feldspar, and mica, which are major components of common rocks such as quartz and sandstone. Mining and processing of these materials are associated with the occupational dust exposure.

Any dust can be harmful to your health, especially silica found in rock, sand, gravel, and clay, with quartz being the most common form. Working with silica containing materials increases your risk of developing lung cancer. When embedded in human lung, silica dust particles lead to permanent tissue damage. Long-term exposure may lead to silicosis, chronic obstructive pulmonary disease, and kidney disease. Currently there is no cure for silicosis, with lung transplant being the only option.

Unloading of silicon metal generated a significant amount of dust at a railroad facility in Carrollton, KY, putting staff’s health at risk.

The facility was receiving silicon metal with lump sizes around 1½ x 1½ x 1½ in. (sometimes larger in one direction) and feldspar particles around 1½–3 in. Handling such lumpy product particles, unusually large and abrasive, required a unique dust solution. In addition, dust management tools needed to be effective for high bulk density quoted at 56–72 lb/cu ft and the dump rate of 180,000–240,000 lb/hr.

A solution for this project came from Australia. Burnley baffles, a dust suppression system, has been developed by Mideco, an Australian engineering company that specializes in dust control solutions for mines, quarries, and any commercial environment where dust is problem. Burnley baffles is Mideco’s internationally patented dust suppression system that is specifically designed to reduce the escape of dust from dump hoppers and chutes handling dry granular bulk raw materials. When applied to a hopper alone, Burnley baffles can eliminate up to 80% of dust. With an additional dust collector applied directly to the hopper 100% of dust suppression is possible. 

Why were Burnley baffles so effective in this case? First, the design of the system makes this a flexible tool suitable for a hopper of any size. It consists of a set of modules with blades that fill the open inlet face of a hopper. During loading or unloading, the baffles strip the air moving into the hopper off the product particles. This is because the air pressure on all sides of baffles is all but constant. The air is not heavy enough to open the blades, which allows for only the product to enter, keeping the dust below the blades. The design of the system uses the principles of air movement and no complicated installation and hardly any maintenance is required.

Secondly, Burnley baffles are highly customizable, meeting the challenges of heavy applications, such as silicon metal in this case. There are five different models available. For this particular project, Model 5, ideal for bulk material consisting of larger particles, was recommended.

In addition, the system can be manufactured from different materials when required. For this application, the baffles were made from 16-in.-thick Endura steel. They had to be heavy and of welded construction to withstand the high bulk density of such product long-term.

The photographs demonstrate the effectiveness and advantage of the Burnley baffles. In this case, there was no dust collection system installed. However, the difference in “before” and “after” photos is evident.

The project was successful in KY, and the client’s feedback has been very positive. It was an example of Burnley baffles streamlining the handling of dry granular bulk materials and protecting employees’ health. It’s a well-established dust suppression system with hundreds of installations in Australia and around the world. They are currently installed at various facilities in Canada, the U.S., New Zealand, Uzbekistan, China, the UK, and Ireland, among others.

Burnley baffles can be utilized in ship unloading, rail unloading, truck unloading, bag tipping, drum tipping, and front-end unloaded material transfers. Regardless of what your business dust issue is and application, this system can suppress up to 80% of dust without additional dust collection equipment. 

Nunawading, VIC, Australia +61 3 8873 0200 www.mideco.com.au

More articles on dust collection:

Dust and Fumes: The Most Dangerous Culprits in Industry

What You Need to Know About the New Edition of NFPA 652

How to Use Dust Explosion Test Data to Ensure Facility Safety

Explosion Containment: A Comparison

Dust Collection Systems: 10 Common Questions