GR Plant proving their metal
Steel making has always been seen as a dirty, but necessary industry. And whilst this was once true, advancements in material recycling and material re-use now sees almost every single piece of what was once waste material leaving a steel works now being recycled...
Celsa steel works sitting on the banks of the Taff in Cardiff, is one of the UK’s largest producers of steel reinforcement products delivering over 1.2 million tonnes of material to the UK and Irish markets annually.
The huge electric arc furnace at the state-of-the-art plant handles thousands of tonnes of steel on a daily basis and ends up producing huge quantities of arc furnace and pit waste. This waste has traditionally been sent to landfill as it is a mixture of lime, steel, and other aggregates from the steelmaking process.
With the cost of landfill increasing hugely and the company’s desire to look at other greener alternatives to disposal, options for recycling the material have been explored and instigated. Celsa, working with Harsco their processing and material handling provider, asphalt recycling specialists Steelphalt and Swansea based GR Plant have built a system that can take the waste material from the production process and recycle almost 100% it.
Like any typical steel making process, elements are mixed according to the precise requirements of the steel and once melted, the remaining slag is taken from the mill and transferred to a tip site where, at 800°c it will sit being turned on a regular basis until it comes down to a more manageable 80°c.
The huge site opposite the mill is home to a range of machines operated by GR Plant, who have been ensconced at the steelworks for the past 14 years mastering the art of recycling the slag. Looking like a moonscape, the entire site is grey from the material the machines handle and move around. Over 25,000 tonnes of slag is handled by the team on an annual basis and to do this, a range of machines have been sourced to cope with the extremely arduous conditions.
GR Plant have built themselves an enviable reputation across the globe for delivering a variety of environmental engineering projects and trail construction works. Built out of owner Gareth Rees’s passion for cycling, the company has successfully delivered numerous high profile trails courses including Lee Valley for the 2012 Olympics. Whilst the environmental side of the business flourishes undertaking a variety of disciplines, the company is also busy with their crushing and material processing teams on contracts such as Hinkley Point and Celsa. Starting out with a Ford H45 at the age of 22 in 1989 undertaking the construction of mountain bike tracks, Gareth has developed the company to a point where there are over 50 machines on the fleet and a staff of almost 20 operators, and engineers.
The work at Celsa has called for the GR Plant team to look at machinery that is not only reliable, but also capable of dealing with the extreme conditions on site. From the cooling slag to the steel recycling, the list of machines has all been sourced and adapted by Avonmouth based Molson Group. “Gareth has developed a brilliant working relationship with the Molson team over the years and we buy almost all of our equipment through them.” Contracts Manager Rob Jones commented. “We know that they have a broad range of machines that will fit our requirements exactly and when it comes to some of the kit we run at Celsa, they are able to make any adaptations in-house and deliver us a machine that can go straight to work.”
The first part of the process for the GR Plant team is sorting and handling scrap steel. For this process they have purchased five Sennebogen 830E material handlers. The wheeled material handlers sort any incoming material removing and contaminants before loading it into a mobile shear which cuts the scrap into shorter lengths to fit into the furnace. “The Sennebogens are a great piece of kit.” Rob commented. “They are reliable and solidly built giving us very little in the way of issues. Fitted with a 17m reach and 600 litre five-tine grab, the 830E tips the scales at around 38 tonnes. With the steel cut and stacked, it is then transported when required and loaded into the furnace.
Moving on to the back end of the recycling operation and once the slag has sufficiently cooled, it is stockpiled allowing it to be pre-screened prior to the final crushing and screening operation. A pair of Hyundai wheeled loaders play a key role in the management of the material both pre and post processing with a 24 tonne HL970A and the largest Hyundai loader, the 31 tonne HL980. Like the Sennebogen material handlers, the wheeled loaders have a key role to play in keeping the back-end operations running. Moving the material from process to process could be undertaken with an excavator and truck but with the material and processing points spread apart, the wheeled loader working a load and carry system is seen as the easiest and most efficient process.
The cooled slag is first passed over a heavily modified Finlay 693 screen. Modifications to the screen have included a reinforced and lined hopper, upgraded rip-stop belts, additional magnets, and protective plates to the external sides of the hopper to prevent potential damage to the machine. These modifications have been undertaken as the slag contains large quantities of metals left over from the steel making process. 125mm hexagonal punch plate has been installed over the grizzly bars on the hopper to try and divert as much steel from entering the screen deck itself. Metal coming off the magnet and grizzly falls to the floor where one of the five Sennebogen material handlers sifts through it with a magnet before depositing it on the side. This material is then transferred to the other Sennebogens where it is sheared and set aside to re-enter the steel making process.
The screened material coming from the Finlay 693 is then moved to the second stage in the process where it is crushed and screened. Site Foreman Kevin Norton takes up the story; “Over the years we have used a variety of crushing and screening equipment to get the right size and cleanliness of material. This train we are running now does exactly what we want and can produce a steady quantity of material so long as what we feed in isn’t too wet!”
The material the company requires goes into the production of asphalt by Steelphalt. The Rotherham based company has been using reclaimed steel mill material for over half a century. The exceptional strength and durability of steel slag extends the life of the road and increases the time between road maintenance needs. The reclaimed steel slag achieves and maintains high skid resistance throughout its whole life on the road as a result of its capacity to regenerate its surface roughness over time and not only provides a more durable surface but also increases the longevity of a road topped with this material.
The processing plant employed by Gareth’s team consists of a Hyundai HX300AL loading a Finlay 694 screen producing four products. Oversized material from the screen is fed back into a Finlay C1540 cone crusher which reduces it down to size before putting it back into the 694. Two finished products come off the 694 at 4mm and dust with the larger material being sent to the first of two Terex Ecotec TTS 620T trommels. These heavy-duty tracked trommels have been fitted with different sized screens to allow a further three finished products sized at 6mm, 10mm and 12mm. The resulting materials are used both in the production of asphalt at the on-site Steelphalt plant and are also shipped around the country for use in other manufacturing plants. The larger product is in particularly high demand as a road dressing product with Steelphalt’s Rotherham plant taking almost every tonne of material produced.
While GR Plant are not contracted to produce a minimum tonnage of material per week, Kevin and his team have to ensure that the incoming material is handled as quickly as possible. “We need a reliable fleet of machines and Molson have been able to supply us just that. On the rare occasions we have had an issue, they have responded very quickly to our call. The kit here takes a fair beating but has stood up to the test. We do tend to change some of the machines sooner than we would normally, due to the work we do.” He commented. Rob is also very pleased with the service and back up they get from Molson. “We do have our issues occasionally, but overall, they are a great company to deal with. We ask them to supply at our specification and they do just that. They look after us from a service point of view even though they know the pain we put the machines through. They are a very fair and open company to deal with and one will continue to do so going forward.”