The Great Recycling Bamboozle
As the Environment Agency and WRAP seek to tighten up the regime on recycled aggregate production through the Quality Protocol, skip waste processing expert Andrew Hewitt argues that some of the problems surrounding increasing the quantity of high quality material on the market is to do with waste firms being bamboozled by plant companies desperate to jump onto the recycling bandwagon without the required knowledge of how systems need to work.
I read with interest the article in the last issue of MQR on poor quality recycled aggregates and began to relate it to my recent experiences trying to find a new project to occupy my time. It dawned on me that some of the things I’d seen in terms of plant specification and project management could be directly related to the poor quality of a lot of the recycled aggregates on the market.
Companies undertake recycling programmes purely for economic reasons. If it was still a viable proposition, most waste companies would be perfectly happy to fire everything into a hole in the ground and be done with it.
In general, people will put making money over investing in plant every time. However, the Government has engineered a situation through taxation where we must recycle. It is probably one of the better things they’ve done. It’d be good to see a lot more of the money coming back into the industry but that’s a debate for another day.
The point here is that there are now many, many companies recycling because they have to. And in most cases this involves buying and operating large expensive machinery. The larger independent companies can buy the knowledge and experience if it can’t be found in house. This is not so in smaller firms and mistakes are being made.
If you’re going to market a good WRAP Quality Protocol guided recycled aggregate you will need a good quality sorting plant, a good robust crusher and a decent washing plant. And that’s a £2.5million investment just to begin with.
This is a lot of investment and the natural approach is to cut corners. This is resulting, I believe, in the aggregate recycling system starting to fail. The quality of the plant is not up to specification.
Recycling systems are a band wagon for anyone who has ever made a screenbox or a conveyor, and they are all hurrying to jump on it. And I believe many of these suppliers are jumping before they fully understand what is fully involved in recycling waste.
The technology in the aver-age waste plant is nothing new. Unless your company has the budget to look at Infra-Red or some other form of automated sorting process then there is nothing on the type of skip waste plant you will purchase that has not being working in quarries or agriculture for the last 50 years.
But I’ve seen proposals for systems that are so complex, so full of machinery and so expensive that the layout drawings alone look like the wiring diagram of the Mars Lander. In most cases the waste would get dizzy long before it got separated. It needs to be kept simple.
Production figures are another area where skip firms and potential recyclers are being led astray. As a general rule, if you are recycling 30tph of skip waste you are working well, that’s one large full grab per minute,every minute of the hour.
If you lose a couple of minutes with a tangle on the picking line then you have to catch up to keep to your 30tph. Just because the plant has 10 bays in the picking station doesn’t make it recycle faster, it just means you can separate a greater variety of materials.
But I’ve seen plants with picking belts so wide that unless you’ve got King Kong working for you nobody can reach the middle of the belt. I’ve seen picking lines with material 600mm deep travelling along it.
I saw recently a couple of quite new plants working where the picking belt was moving so fast the pickers couldn’t keep up. It must have been doing 0.5m/s. This is all in the name of throughput.
Of course, after a week or so working the operator had to set aside one bay at the end of the line to scoop in everything that the pickers can’t get at. It’s the fullest bay in the station and it is filled with material that looks just like the waste that’s fed in at the beginning of the operation minus the fines.
When you start to tell people that there is an industry standard for picking belts covering size, speed and the operating position of the pickers, many of them are quite surprised. If one of your pickers hurts his back on your line and your machine is not within the industry standards the company can find itself in very hot and expensive water.
And it’s not only health and safety issues in the picking station that seem to fall short. A good plant needs to be accessible in all areas for cleaning and maintenance. You can no longer use ladders or climb up a conveyor belt to get where you need to be. It has to be a safe and secure walkway.
Unfortunately, with the price of steel as it is a good walkway system is an expensive thing to have on a plant and when two prospective suppliers find themselves vying for a contract losing sections of walkway is an easy area to reduce the price.
It is not acceptable to leave the plant operator with a note in the small print stating that a cherry picker or hydraulic platform must be used to access some areas of the plant. After the second tangle of plastic around the troughing rollers we all know the operators will be straight up the belt to sort it out.
Another area of the plant shrouded in confusion is magnetic separation. It looks easy. All you need is an overband magnet. Job done! But, yet again, it’s not quite that simple.
On the fines line – material <50mm3 – a permanent magnet set 250/300mm above the belt is normally more than adequate. If you pick the right magnet it is possible to extract 90%+ of the ferrous metal in the material flow – such as nails, staples, nuts and bolts and bottle tops that are not easily seen in the material.
But physical differences in an overband magnet that will be efficient at an operating gap of 100mm compared with a magnet designed to operate at 300mm over the same width belt are not immediately obvious.
You have to measure the size of the magnet block and check the gauss reading. The same applies on the oversize material where you need an operating gap of 500/600mm so large bundles of material don’t get caught around the magnet belt.
The difference in price is another matter. A good magnet compared with an also-ran
can vary in price by several thousand pounds. Economy on magnets is always false. On the fines line, in particular, a good magnet costing £7,000- £8,000 will pay for itself in a couple of months.
My concerns do not lay with the differences in types of screen such as whether a trommel or a finger model is best, or whether you should use a starscreen or a tension deck / flip-flop screen. Decisions like that will be made from the personal experience of the operator.
The message I’m trying to get across is that basic lack of knowledge on what waste plant is and what it can achieve is being used to blind companies with science as the UK struggles to improve its C&D waste processing capacity.
There are many plants out there that are over complicated and overpriced – sometimes by as much as hundreds of thousands of pounds – that don’t really work that well.
If the goal is for an industry producing quality recycled aggregates to aid in lowering the use of primary materials then you have to start with a good recycling plant. Otherwise, a long term market will fail to establish itself.
Andrew: 07773 715882
