Things That Go “Bang” In The Night
Actually, they’re usually during the day, but saying “night” is more colourful.
I’m sure we would all agree that loud unexpected noises can be big problems. At least when we are blasting at a mine or quarry site it can be said that the noise is expected, so it’s less of a surprise.
But if you conduct a business where loud explosions occur more or less randomly, both you and your neighbours will be less than amused.
This can be your life if you run a metal recycling plant.
So who would want to operate a metal recycling plant anyway?
It turns out that metal recycling is not only good business, but also an important one – both commercially and environmentally.
Commercially it is extremely beneficial because you can continue to recycle metals almost indefinitely without degradation of any of the properties, and it is far cheaper to recycle than to utilise metal derived from mined ore.
But the biggest advantages are probably environmental. Making products from recycled metals uses less energy, reduces carbon emissions and uses less water compared with using raw materials.
For example, for every tonne of recycled metal, estimated savings are:
- 66 tonnes of CO2
- 5,588 kWh of energy
- 73 kl of water
- 04 tonnes of waste
These numbers are averages across all metal types.
Interestingly, aluminium offers the biggest energy savings. Refining aluminium uses about 211 GJ per tonne, compared to 22.7 GJ per tonne for steel. Because refining aluminium is so energy intensive, aluminium is often referred to as “congealed electricity”. However, recycling aluminium uses 95% less energy than producing it from the raw material!
Why does aluminium refining require so much energy? As you know, metals in the ground exist in their oxide format (after all, it is difficult to keep water and oxygen away from metals in the ground!), and the Al-O2 bond is much stronger than the Fe-O2 bond, so it requires much more energy to break it.
All this means that there are very significant reasons for recycling metals.
But, as with most good things, there are problems. The ones we can all readily understand are the logistical ones – collecting the scrap, transporting it to processing plants, separating the metal types, etc.
One that is not so obvious is the tendency of these plants to go “bang” from time to time. And the bang can be pretty significant – it can injure people, damage plant equipment and cause great concern for neighbours.
The cause of these explosions is the presence in the scrap metal of flammable materials. Some common flammable materials encountered are residual gases in propane tanks, aerosol bottles, etc as well as residual fuel in cars and trucks. Perhaps less frequent, but critical, is the presence of undetected munitions in military scrap. Military scrap is highly sought after because armoured vehicles contain not just steel but also premium metals such as copper.
What causes these materials to detonate varies. For example, crushing a car with fuel left in its tank can cause detonation of the fuel. The use of high-temperature tools (such as torches used to cut up large scrap) may ignite the flammable material and cause both fires and explosions.
Well, that’s why things go bang “in the night”. But what can be done to reduce these events?
There are electronic explosive material detection devices available that scan incoming metals for explosive material. These devises are particularly useful if the plant frequently receives military scrap metal.
Otherwise it becomes a matter of appropriate work procedures. Fundamental procedures become very important. For example:
- Provide sufficient time for workers to sort incoming materials
- Separate hazardous and flammable materials from all other materials as early as possible in the recycling process
- Isolate workers from potentially hazardous work process, particularly metal shredding.
While these recycling operations have traditionally existed in industrial zones, growing city populations and urban sprawl have resulted in many of these sites now coexisting amongst residential and retail shopping areas bringing with it a raft of environmental compliance conditions to continue operations. At Texcel, we have been able to support the sustainability of these operations by providing a turn-key managed system which simplifies compliance data and reporting for management to allow the operators to focus on what they do best – recycling! As an independent expert we are able to ensure the data that is timely, reliable and accurate. Texcel has worked with many of the metal recyclers throughout Australia to set up appropriate monitoring and reporting processes.
For more information, please reach out.
