The Site from Hell

• 
• 18th June 2008
• Recycling
 

With wheel loaders carrying molten slag and screens handling two tonne chunks of iron, the Celsa Manufacturing UK Ltd steelworks at Tremorfa in Cardiff is the ultimate test for mobile plant, particularly the new Extec S-6 screen. 

With jagged concrete, sharp reinforcing bar and hidden pitfalls, demolition sites are often described as arduous applications for mobile equipment.   Similarly, waste transfer and landfill sites with their unseen hazards are viewed as a hostile environment for even the most robust and durable of plant.   But, frankly, these are a veritable walk in the park in comparison to the machine working conditions at the Celsa Mineral Works at Tremorfa.

In fairness to Celsa, the company has done an incredible job of hiding precisely what takes place in the eight hectare site.   Approaching the site, visitors drive past a pristine, new housing development and the ubiquitous Tesco superstore.   Seconds later, they are greeted by what could easily be mistaken for a lunar landscape where everything is covered in a thin veil of grey dust.

Created originally to salvage scrap from the slag processing work carried out at the Tremorfa steelworks, the site is now equally busy extracting value and profit from what was traditionally thought of as a pure waste by-product: slag.   "In the past, slag was seen purely as a waste product and was often simply tipped into the sea," explains Tom Taylor, managing director of Taylor Site Services Ltd, a key equipment supplier on the site.   "But a combination of greater environmental awareness and a change in ownership means that everything on the site is now recycled, reclaimed or reused."

A key part of this process involves the reclamation and processing of slag from the site's electric arc furnace.   Hauled to a dump area by at Caterpillar 988G wheel loader equipped with a 7.0 m³ capacity bucket, the molten slag is tipped into a series of holding pits where it is sprayed with sea water to cool its 1,300 degree temperature to something a little more manageable.   Crushed and untreated slag is regularly used as a landfill bunding material but if it is allowed to weather for six months, it can be used as a highly acceptable sub-base or in concrete mix.   "Slag is a really tough material to work with," Taylor continues.   "It is highly abrasive, hard, heavy and yet extremely brittle.   And once it is wet, it sets like concrete."

The machine on the wrong end of this material is a new Extec S-6 track-mounted mobile screen and, according to Taylor, the 49 tonne unit is proving more than a match for the material and the two screens it was purchased to support.    "There have been two competitive screens on the site for some time now but they have been terribly unreliable.   We are currently achieving twice the production of the other two screens combined...when they are working."

Taylor reports that the benefits of the new Extec screen first came to light during the installation and set-up procedure.   "We bought the S-6 on the advice of local Extec rep Danny Morgan," he says.   "The machine arrived on site at lunchtime and by 3 pm it was hard at work with no troublesome and time-consuming adjustments to make."   The S-6 is currently producing a range of materials including a 5" product, Type 1, and oversized which is re-circulated for further processing.

The Extec S-6 is loaded by a Doosan DL500 wheel loader equipped with a 5.2 m³ capacity bucket.   "The wheel loader was purchased as a match for the screen but the wet slag does have a nasty habit of sticking together," Taylor continues.   "It is not unusual to bounce a two tonne chunk of steel off the screen, which is hardly ideal.   But the screen is coping remarkably well."

It is more than coping.   In a recent timed loading test, the Extec S-6 processed 109 tonnes of slag in just 20 minutes.   And in September of last year it surpassed the site record, processing 19,000 tonnes in a single month.   "Using the two existing screens, we were able to clear one holding pit per week," Taylor adds.   "The Extec S-6 is able to clear two pits per week on its own."  

Key to the success of the Extec machine on the site, according to Taylor, is the length of the conveyors.   "The S-6 comes equipped with long conveyors which allow us to create large stockpiles of 400 tonnes or more.   This means that we don't constantly need a machine running around maintaining a series of smaller stockpiles," he asserts.    "The Extec is also very clearly built to withstand such a harsh environment.   All the electrical cabling and hydraulic circuits are covered; the key maintenance points are all easy to access; and the bearings are sealed for life.   With our previous machines, we went through seven sets of bearing in just six months!"

Taylor says that he has also been impressed with the ease with which screen media can be changed.   "The S-6 has two shaker boxes which places far less strain on the Deutz engine while providing a high vibration rate for much more thorough screening," he continues.   "The unit's magnet is very effective at picking out iron from the slag, and the screens can be changed in around 20 minutes, minimising downtime and ensuring that we're always operating at full capacity."

"The Extec S-6 has proved to be more than a match for this site and if it can work here, it can work anywhere.   I am actually hoping to have a second unit, possibly with an Extec C-12+ crusher, on site later this year," Tom Taylor concludes.   "Thanks for the Extec machine, we have been able to turn a waste product into an environmentally sound, saleable and profitable material."

For further information, please contact: Extec Screens & Crushers Ltd. Tel: +44 (0) 1283 21 21 21 Fax: +44 (0) 1283 21 73 42 E-mail: info@extec.eu Website: www.extec.eu

For further information, please contact: Fintec Crushing & Screening Ltd TEL: +44 (0)28 8556 7799 FAX: +44 (0)28 8556 7007 Website:  http://www.fintec.com/

 

Associated Links

• Hub-4 Profile of Extec Screens and Crushers Ltd
• Extec Screens and Crushers Ltd Company Website