Kevin Jeffries, Imperial’s safety systems manager, last week gave a talk to confectionery and bakery processors such as Hershey’s and Mars, Kellogg’s, Sara Lee and Krispy Kreme about the importance of maintaining a safe work environment and the potential hazards of uncontrolled sugar dust and other dust during food processing.
Imperial said that it has generated a considerable body of knowledge around the explosive properties of sugar dust by analyzing the sugar process and conducting ongoing laboratory tests on all of its products, related raw materials, and intermediates since the explosion at the Port Wentworth refinery in 2008.
Ron Allen, safety symposium organizer and Imperial Sugar’s senior director of environmental health, safety and quality, also presented last week on the explosive characteristics of sugar, and he said that the supplier feels a professional commitment to share its findings on combustible dust technology following on from the deadly blast.
Inadequate housekeeping
The deadly explosion at the refinery was fuelled by a build up of sugar dust in the packing plant and was “entirely preventable” said the US Chemical Safety Board (CSB).
Inadequate housekeeping practices and the failure by company chiefs to take action despite being aware of the hazards were two major causes of the blast that ripped through the Georgia facility in February 2008, killing 14 workers and injuring 36 others, said the safety body in its final report released in September 2009.
The CSB said the explosion resulted from ongoing releases of sugar from inadequately designed and maintained dust collection equipment, conveyors and sugar handling machinery.
The primary blast occurred inside an unventilated sugar conveyor that allowed sugar dust to build up to “an explosive concentration”, explained the CSB. An overheated bearing was the likely spark that caused the explosion which triggered further blasts as it travelled into the adjacent packaging facility.
Knowledge sharing
Jeffries told the assembled confectionery and food company representatives that under the right conditions sugar dust can ignite on hot surfaces, and explosions can be ignited by static electricity or sparks from hot work, such as welding and acetylene burning.
He said that these events can occur in milliseconds and often inside equipment such as silos, granulators, bucket elevators, enclosed conveyor belts or powder mills.
The safety systems manager also explained that dust accumulations on rafters, beams, and building steel can also be a concern and that housekeeping thus is extremely important.
“A small amount of dust when suspended in the air’’ can result in an explosion, Jeffries claims.
Vulnerability reduced
Jeffries said Imperial has implemented new procedures and controls, which have further reduced vulnerability through standard operating procedures, housekeeping controls, employee training, and maintenance regimes.
The initiatives are in line with what CSB has recommended in its safety report last September.
The US sugar and sweetener supplier said that it has developed a computer-based combustible dust training programme in conjunction with an independent firm of scientists and engineers that its managers, employees and contracts must all pass the course before they can work at either of its plants.
And the company explained that it currently uses a “Housekeeping Audit Form,” which scores each area of the plant on cleanliness in multiple categories to assure that volumes of combustible dust are kept to a minimum.
Imperial said that it has invested in a new state-of-the-art packaging and bulk loading facility at Port Wentworth and it now has local exhaust ventilation and central vacuum systems, chemical isolation and suppression systems, dense-phase conveyance and a variety of other control technologies to prevent accumulation of static or other ignition sources.
The dust safety presentation can be accessed here.