Wind of change

• 
• 22nd December 2008
• Recycling
 

Ross Matthews visits DTS Environmental in Barnsley to see how a new Waste Separation System, incorporating air separation technology, operates at the heart of the company's developing recycling business.

DTS Environmental is changing. It has set its course towards a greener future by making a significant move into recycling more skip waste rather than sending it to landfill. A "serious investment" in a new building, plant and equipment at its Recycling Centre site in Carlton, near Barnsley, will play a central role in this development.

The company's name itself reflects a new, greener ethos. Originating from D Thackery & Sons, formed in 1964, the company developed through the years to become, in May 2007 DTS Environmental Ltd and today operates in the areas of skip hire, demolition, excavation, plant hire and haulage and, of course, waste management.

Having previously operated a mobile trommel and a mobile picking station on site, where a limited amount of picking from waste took place out in the yard, DTS began to look at what others were doing in the wider recycling world.

"We wanted to grow into something entirely different," explains Darren Jones, DTS Environmental Limited's general - waste manager, "and become a total waste management company so we looked at the technology across Europe."

When it came to replicating at its site in Barnsley the technology they found during their search, DTS were presented with a variety of solutions but it was Steve Hill, whom DTS had worked with previously, who grabbed their interest with a Waste Separation System offered by the company where he is the UK sales agent: Smulders Waste Technology.

"It wasn't the cheapest plant nor was it the most expensive but Smulder's solution offered the best value," says Darren who also saw the company as something of a soul mate. "We are a relatively small company going to the next level and through Smulders' active cooperation we were able to come up with the best solution to suit our requirements."

To provide a good working environment and reduce noise levels at its Recycling Centre DTS constructed a building with a 30 x 50 m footprint and a 9 m ceiling height to house a Waste Separation System. Completed last year, the building's dimensions were dictated by planning requirements. Smulders produced a plant design that fitted neatly inside and commenced installation during the spring of 2008.  Work was completed by the end of the summer and during HUB 4's visit in mid-September the plant was running through the commissioning process to be fully operational at the end of September.

Sorting out the waste

With a capacity of 120 m³ per hour, the new Waste Separation System is designed to handle general construction, industrial and skip waste. DTS has its own fleet of skip wagons to bring in about 100 skips a day of mixed waste from the local area. Once over the weighbridge the skips are tipped and the waste is presorted to segregate large and unwieldy pieces. The remainder is then processed by the Waste Separation System.

The system starts with a 10 m³ hopper manufactured from Hardox, which makes it tougher than the average hopper, into which the presorted waste is loaded by a grab. Waste material is then fed to the high stroke vibratory feeder, which transfers the material onto a 1200 mm wide trommel feed conveyor. Impact bars at each transfer point of this waste recycling system cater for handling the heavier items coming through.

From the feed conveyor the material enters an 8 m long x 3 m diameter trommel screen, which is equipped with changeable decks. With its lifting and tumbling action, this heavy duty, chain driven unit is fitted with 40 mm diameter decks to separate the fines that are then collected by a conveyor and transferred up to a fines screening station, on to a single deck screen, which is 1800 mm wide x 4000 mm long fitted with 20 mm rubber screening panels. The -20 material is too small to go through cleaning -  "It's the big problem everybody has as currently there's no means of cleaning the small fines," says Darren - and is conveyed into a bay outside the building.

The 40/20 mm material then travels under Smulder's Air Waste Separator unit mounted across the vibrating screen to suck off the lighter materials.The contaminated materials are sucked towards a heavy, rust-free chain belt and discharged at the side via a chute into a skip. The dust control is via a fully automatic reverse air jet filter unit.

The material that passes under the waste separator then discharges onto a conveyor to remove any ferrous metals. The material left on the conveyor then passes through a one-bay picking station to remove any non-aggregate materials and the aggregate then discharges into the bay outside the building.

The +40 mm oversize material from the trommel discharges on a 1200 mm wide conveyor, which has an overband magnet mounted above it to remove any ferrous metals. The material left on this conveyor is then conveyed up to the picking station, which provides a far better working environment than the situation before when staff were picking what could easily be picked from the waste pile outside. The modular picking station, which can be extended if required, comprises a cabin with four chutes either side of the 1200 mm wide conveyor belt, allowing 10 pickers to work simultaneously to sort out the material to be recycled, which is dropped into the chutes leading to containers for each material below the station.

"I don't think there is enough time to segregate all of the cardboard and paper up here and that will get re-picked," explains Darren. "We are thinking of refurbishing our existing equipment to use as a secondary picking station and pick it down into different streams again."

Material leaving the picking station discharges onto a conveyor and passes under another overband magnet to remove the ferrous metals - the non-ferrous metals are hand-sorted and collected inside the picking station. The remaining waste then passes into an air separation system.

The air separation system comprises a 250 High Pressure Fan with an air knife mounted under the head of the conveyor blowing light waste away from the heavy waste, light waste is then sucked into a 500 Heavy Duty Chopping Fan and then via ductwork up to a WS 16 Waste Separator, which separates the air from the waste, with the waste dropping into a container and air discharged directly into the atmosphere outside the building. The heavy material, which is mainly clean hardcore, finally then discharges into a bay outside the building transported on conveyors constructed by DTS itself. "We have designed this so that we can back our mobile crusher underneath the belt so providing direct feed to a crusher as we know it's clean and without contaminates," explains Darren. "Rather than have a fixed crusher we can use our mobile plant for crushing or move it out to allow the hardcore to fall into the bays."

The plant's electrical control system incorporates a PLC with built-in safety features. The system starts and stops sequentially at the press of a button.

The air suction units on this system are an interesting alterative to traditional fan blowers. "The Dutch call it a wood magnet as it can pick up bits of wood as well as hard plastics, paper, polystyrene etc. It's something that Smulders has developed over 20 years. A Reverse Jet Filter removes any small material and dust from the air which then discharges air inside the building the air being much cleaner than the defined maximum exposure of 10 mg/m3 so there's no external discharge," says Steve Hill.

"There's no way anybody could pick all of that off," says Darren looking at a skip full of wood-leaf collected by the air suction unit. "What has surprised us is the amount that we are lifting off. Originally we only had a small skip to collect what we thought would be emitted but it fills a full skip in about an hour." In fact DTS plans to add a conveyor belt to take this material to a bigger skip.

Benefits for DTS

The new plant will enable DTS to recycle 85-90 percent of incoming waste - that's a significant 40% improvement over what it could previously achieve - and to clean the fines up as much as possible.

"This system can handle 120 tonnes per hour so it's up to us to get the business up to that level," says Darren. "We are reducing what we are sending to landfill and maximising recycling and also gaining, cleaner, more saleable products from the waste. We have identified markets for the various materials that we are recycling and we are going to start a bailing system also."

DTS's development of its Barnsley site doesn't stop with this new plant: a new office block and staff welfare facilities will also be constructed.

"Our vision is to grow the business and become a major player in the market," says Darren. "Landfill tax and legislation means that the sector has to be more commercially aware. More and more materials, such as plastics, are becoming recyclable and the technology is developing all the time - even between the conception of a recycling plant and its installation - while the markets for these products continue to open up," says Darren who explains that to capitalise on this opportunity does require confident investment: "You either recycle in a big way or you will not get anywhere so you need a major investment into kit such as our new system. We decided if we are going to get involved in this we needed to invest heavily and start recycling from day one rather than installing outdated equipment. Having been round other plants where the equipment we saw is now outdated we wanted to start from day one with a state-of-the-art system. We can adapt this system and keep moving on; there will be a growing number of larger companies entering the market and a facility such as this will give us the edge."

The areas's local construction companies are happy as the facility will provides them with a cost saving. However with this sector currently being credit crunched, so the amount of C&D waste produced is reducing. However, there will always be waste and the private sector and domestic sectors continue to provide plenty. DTS is also looking to broaden its working area into other parts of Yorkshire.

Darren concludes: "We are recyclers now, we are not sending waste to landfill. We have the machinery here for recycling and helping companies meet their recycling targets."

Smulders Waste Technology B.V.
P.O. Box 47, 5730 AA,
Industrieweg 2, 5731 HR,
Mierlo
Netherlands

T: + 31 (0)492 664 885
F: + 31 (0)492 664 695