Dust can be a dangerous thing! It can literally cause explosions! Here is some interesting information on dust explosions and what causes them as well as news of an event that took place in Tilbuy, England in August this year.
“Dust explosions occur when combustible dusts build up in the air and combust rapidly, causing a strong pressure wave to form. They are a deadly hazard in a variety of workplaces, from grain silos to plastics factories. A dust explosion requires several factors to be present at once. These include:
A combustible dust at the right concentration level
Oxygen
An enclosed space
An ignition source
Sometimes these factors are combined into a graphic known as the “Dust Explosion Pentagon.” The component in this graphic called “dispersion” is also known as concentration. If a concentration of dust is too low, there is not enough of it present to fuel an explosion. If the concentration is too high, there is not enough oxygen to support combustion.
While some combustible dusts are easy to guess—wood and paper dust, for example—others aren’t, such as aluminum dust. Combustible dusts become more dangerous as particulates become finer. These dusts feature a high ratio of surface area to volume, adding to their combustibility. When these dusts combine with oxygen within a range of concentrations, a dust explosion is possible.
In these conditions, all that is needed for an explosion is an ignition source. This source can be anything from a cigarette to a spark to an overheated wheel bearing. Under the right conditions, some combustible dusts can self-ignite as a result of static that builds up as particulates rub against one another. The ignition causes the dust to combust quickly—a process called deflagration that creates a wave of high air pressure. Sometimes this explosion can stir dust that has settled in the space, creating a cloud of new dust—a fuel source for an enormous secondary explosion. A dust explosion can blow out walls in a facility and kill or injure workers within the space or nearby.”
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“Dust explosions pose the most serious and widespread of explosion hazards in the process industry alongside vapour cloud explosions (VCE) and boiling liquid expanding vapour explosions (BLEVE). Dust explosions almost always lead to serious financial losses in terms of damage to facilities and down time. They also often cause serious injuries to personnel, and fatalities. We present the gist of the dust explosion state-of-the-art. Illustrative case studies and past accident analyses reflect the high frequency, geographic spread, and damage potential of dust explosions across the world. The sources and triggers of dust explosions, and the measures with which different factors associated with dust explosions can be quantified are reviewed alongside dust explosion mechanism. The rest of the review is focused on the ways available to prevent dust explosion, and on cushioning the impact of a dust explosion by venting when the accident does take place.”
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Tilbury Port Grain store blast caused by ‘dust explosion’
Published20 August
For the original article – BBC News – Click here
“A blast that partially destroyed the roof of a large grain store was caused by a rare “dust explosion”, a fire service has said.
The explosion at Tilbury Port on 3 July was described as “like a bomb going off” with flames 75m (246ft) high.
Essex Fire and Rescue said the cause of the fire was recorded as “accidental” and no-one was injured.
“Dust explosions like this are very rare but occur if the dust reaches a flammable temperature,” it said.
The port said it had commenced “a phased start-up of operations at the terminal” last week.
When crews they found grain on fire inside the plant but were able to remove unaffected grain so it did not ignite.
Fire crews remained on site for 20 days extinguishing fires in the grain stores and preventing damage to the site.
A metal dust explosion in 2014 caused a blast that tore through a plant in eastern China, killing 75 people.
And 14 people died in an explosion at a sugar refinery, caused by exploding sugar dust, in the US state of Georgia in 2008.
Peter Ward, commercial director of the Port of Tilbury, said grain handling and storage had carried on at the port shortly after the fire.
He said the phased return to full operations was “a credit to our port team and their fantastic effort to restore the facility during these challenging times”.
The grain terminal at Tilbury opened in 1969 and is the UK’s largest, according to the port’s owners.”
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Dust Monitoring Equipment – providing equipment, services and training in dust fallout management to the mining industry.
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