Whilst waste shredding is an inherently hazardous operation, engineering developments have advanced over the years to protect operators and the surrounding site. However, there is still work to be done, believes UNTHA America’s Gary Moore – but does change rely on technology or mindset?
When it comes to devising a shredder specification, a number of different factors naturally form the ‘wish list’ for the machine. Throughputs, particle sizing, ease of maintenance, price – in truth the list goes on and the exact criteria undoubtedly depends on the waste or recycling scenario at hand.
But irrespective of the project, one thing is for certain – the hunt for optimum performance should never be to the detriment of safety. Few people would disagree that industrial shredding has the potential to be a hazardous exercise, which is why manufacturers over the years have worked so hard to ensure safety – by design – within their equipment.
However, as the industry evolves, demands heighten and workplace legislation tightens, the safety landscape must naturally adapt too. It is no longer enough for shredding systems to be supplied with only simple safety considerations such as diagnostic control panels to prevent machine ingress.
From easy maintenance regimes that minimise operators’ exposure to the inner workings of the shredder, to foreign object protection that auto-stop the equipment should it encounter an unshreddable item, there are many ways to heighten the safety of the technology.
But, given the fatal injury rate to waste workers (in the UK) was 6.8 fatalities per 100,000 over the five-year period 2012/13-2016/17 – around 15 times greater than the rate across all industries during the same timeframe – even more needs to be done. So what will the greatest safety considerations be in 2019?
The issue of noise is currently growing. Workplace legislation exists to protect employees’ hearing, so ear defenders have long been essential within industrial waste plants. However, savvier firms have started to demand more, keen to cap the number of decibels that their plants operate at.
As a result, facilities are now being designed to run below the first dB(A) action point. Because some waste shredders can now function below 80 decibels, for example – especially those with quiet electric drives rather than gas-guzzling diesel engines – hearing protection is not necessary.
Not only does this shield operators from the debilitating effect of prolonged exposure to excessive noise – it also supports morale, sustains productivity and, in the simplest of commercial terms, saves money on ear defenders. There are wider business benefits too, as it helps site owners navigate planning constraints and community complaints, if facilities no longer disrupt neighboring residents.
The risk of fire is also significant in our industry, and the storage of waste is undoubtedly part of the problem. Sprinkling systems are extremely important for obvious reasons, operators need to do their utmost to keep plants tidy and dust-free, and a thorough cleanse of the floor and all machinery is advised at the end of each day. But innovative machinery features can further help avert otherwise catastrophic incidents.
Carefully positioned UV, infrared, heat and spark detectors on a shredder’s hopper and discharge conveyor, for example, can now sense when a fire is likely to begin. In the event of a significant temperature increase, extinguishing nozzles, positioned in the same place as the sensors and thus pointing directly at the fire risk, can automatically spray water onto the targeted area. This means that, if the risk is within the shredder, the materials can be cooled and/or the fire put out before anything is discharged.
If the problem is on the conveyor, the nozzles prevent hot, glowing fractions from entering the pile of output material, where a fire could otherwise propagate. Alarms can even be activated to alert the operator to start a manual extinguishing process, and/or notify the fire brigade.
Explosions are somewhat different. These can be caused if a ‘foreign object’ such as an aerosol tin bursts due to heat or compression, or if a small electrical spark creates enough of an ignition when it reacts with high volumes of dust. To prevent such scenarios, more responsible equipment manufacturers are again reducing risk ‘by design’. Rotor speeds have been slowed, for instance, to reduce the creation of dust, and lower tip speeds mean the potential for a spark is also lessened. Anti-explosive Atex-specification motors and electronics can be installed too.
As with many workplaces, ergonomics are becoming increasingly important in waste. That’s why shredders are now being designed to ensure operators can service and maintain equipment quickly, safely and in an upright position, without the need to hunch or over-stretch. This is of paramount importance given the prevalence of musculoskeletal disorders affecting this industry’s ill health.
Shredders can now automatically stop if unexpected objects are detected, with the machine ejecting the material so that the operator can simply open the door and retrieve the problematic item, without the need to enter the shredder’s cutting chamber.
A safety mindset
The majority of considerations here relate to advancements within the shredding technology itself, but in truth, a holistic safety mindset is required within the resource sector, if the multiple challenges are to be effectively navigated.
Operators need to respect what the shredders are there to do, for example. They should observe manufacturer guidance regarding how the technology should be run and the importance of it being maintained, and if the requirements of the machine evolve beyond the initial scope of the project, the supplier should be contacted for guidance to ensure this will not jeopardize the safety of the operation.
Safety considerations should also begin before the shredder is even on site – it needs to be ingrained in the operator’s culture from day one. The evidenced safety performance of the machine should therefore be carefully assessed prior to purchase, and the safety standards of the supplier should also be audited. From their approach to project management and on-site dialogue/behavior, to the knowledge they have of the wider safety spectrum, these factors will contribute to a robust installation long into the future.