Why Aerosol Cans Should Never Be Put Into A Shredder?

The importance of minimizing scrap contamination during receiving can not be overlooked. The Aluminium Plant Safety Blog has posted numerous incidents where unacceptable material resulted in incidents causing injuries and deaths. Here is an incident that reinforces why aerosol cans are dangerous.

A scrap handling firm in the United Kingdom has been prosecuted following a major explosion at a waste management site that caused three workers to sustain serious burns.

The blast occurred in 2010 when aerosol cans were put into an industrial shredder.

A joint investigation by the Heath Safety Executive (HSE) and the Environment Agency found that the company had allowed around 150 aerosol cans containing extremely flammable substances to be put into a large shredder at the site.

Three employees working near the shredder were caught in a fireball, and surrounding buildings had to be evacuated while the firefighters dealt with the resulting blaze.

Nearly 60 police officers were deployed to oversee road closures and control a cordon around the site. There was extensive damage to the large warehouse that housed the shredder.

The Crown Court heard that the company failed to ensure that a chemical specialist monitored the waste being put into the shredder to check for flammable substances.

A risk assessment, which had been carried out in April 2010, was found to be wholly inadequate after the company wrongly identified the risk of aerosols being added to the shredders as "very unlikely", and the consequences of this happening as "moderate", which meant no action was take as a result.

In October 2013 the company was fined over £150,000 after pleading guilty to section 2(1) of the HWSA 1974. 

Following the hearing, HSE inspector said: "The chemical waste industry has the potential to be extremely hazardous, and (company) could and should have done more to protect the lives of its employees and the public.

"The issue of waste materials being wrongly labeled is well-known in the industry, so (company) shouldn't just have assumed it could add cardboard boxes to the industrial shredder without first checking what was in them."

In a statement, a spokesperson for the company said: "The health and safety of our employees is a paramount importance and this incident dating back to October 2010 is a matter of great regret."

"We have co-operated fully with the HSE and Environment Agency at all times during the course of their investigations and have taken steps to prevent any such incident in the future, including reviewing and updating our processes and investing in state of the art equipment in all of our relevant sites."

Aerosol cans are only one of many unacceptable or restricted scrap contents. Other unacceptable items are:

• Fertilizers and other materials containing nitrates, sulfates or other oxidizing agents; salt fluxes contaminated with nitrates, sulfates or oxidizers, and any unknown powder
• Water, snow or ice in excess of plant processing capabilities.
• Volatile substances in excess of plant processing capabilities.
• Closed containers, crimped tubing, aerosol cans, automobile air bag inflation cartridges, ammunition cartridges, fire extinguishers, freon tanks, oxygen and acetylene cylinders, detonators and similar objects.
• Aluminium fines in excess of plant processing capabilities.
• Heavily oxidized metal in excess of plant processing capabilities.
• Hydrocarbons (e.g., oil, flammable liquids) in excess of plant processing capabilities.
• PCBS or other toxic materials at levels which constitute or create a health hazard.
• Radioactive materials.
• Aluminium-lithium alloys unless specified.

The Aluminum Association (USA) has developed a great publication that is recommended for any plant that receives scrap. The publication can be found here.

The Health and Safety Executive has some useful information on preventing fire and explosions which can be viewed here.

This incident is unique where the APSB post included the root cause investigation done by the proper government authorities. 

The company had numerous failings in several ways resulting with the explosion which injured three workers. It is unknown from the government report how long the company was shredding boxes without opening them beforehand. What is known that 6 months before the accident the company's risk assessment listed "very unlikely" that aerosol cans could be added to the shredder. In addition the company considered these consequences of this happening as "moderate". Which meant no action was taken as a result. In hindsight one wonders why "very unlikely" was not further investigated. 

Please comment.