Motors move mountains

WEG Premium Efficiency motors are used in a novel environmentally friendly conveying solution that has solved a big problem for Midland Quarry Products.

When Midland Quarry Products (MQP) needed to recover the granite reserves from its Old Cliffe Hill Quarry, the company had to overcome the problem that all its processing equipment, crushers, screens and rail linked asphalt plant were in the existing New Cliff Quarry some miles away.

Worse still, a village lay between the two quarries.

Undaunted, MQP came up with a highly environmental solution: a 720m long tunnel through the hillside to link the two quarries.

Now, thousands of tons of rock are transported through the tunnel each day on an overhead conveyor, which was supplied and installed by Whitwick Engineering and powered by specially manufactured drive packages comprising Sumitomo high strength Paramax gearboxes and WEG Premium Efficiency motors.

Midland Quarry Products is one of the UK's leading producers and suppliers of hard rock and asphalts.

The company provides a comprehensive range of single sized and blended drystone aggregates to meet most of the demands of the building, construction and rail industries.

It operates two quarries and five asphalt plants in the East and West Midlands, including the award winning and internationally recognised New Cliffe Hill Quarry in Leicestershire.

In addition to New Cliffe, MQP also has extraction rights at Old Cliffe Hill Quarry a few miles away over a hill; the two quarries being bisected by the village of Stanton-Under-Barden.

The Old Cliffe Quarry has been in existence since the late 1800s; however, the quarry had been laid up for a number of years, the intention being to return to the quarry at some future date to recover the reserves previously sterilised by the old processing plant.

This intention became more urgent recently in the light of declining reserves at the New Cliffe Hill Quarry.

The major problem faced by MQP in bringing the Old Cliffe Quarry back into production was the fact that all its processing plant was situated at New Cliffe, and to move it would not have been practical.

The company therefore consulted with local residents from Stanton-Under-Barden to find the most environmental and acceptable solution to them.

Initially a surface conveyor system linking the two quarries over the intervening hill was considered, but this was rejected by the parties on environmental grounds.

Eventually a scheme was agreed that involved MQP in excavating a tunnel to link the two quarry voids.

This method addressed all the local residents' concerns; it was the most environmental available and offered the benefit of reducing the haul distances and the number of trucks working the quarry.

The only problem was that the 720m tunnel had to be blasted through granite, a project that took two years to complete and cost millions of pounds.

Measuring 9 x 6m, the tunnel is 70m below the surface and is large enough to accommodate motor vehicles.

Housed high in the roof of the tunnel is a large elevated conveyor that is part of a larger system which stretches 1.5km from the new primary crusher in the Old Cliffe Quarry to a similar unit in the New Cliffe void.

This arrangement enables MQP to optimise production across the two quarries.

The primary crushers process rocks at a rate of 2,500t/h.

In this operation rocks measuring up to 1.2m are reduced to just 300mm; they are then carried on the 1.5km long conveyor system to the main processing plant situated at New Cliffe Hill.

The conveyor system, powered by WEG premium efficiency motors driving Sumitomo Paramax gearboxes, is the work of Whitwick Engineering, based in Coalville Leicestershire.

Whitwick designs and builds complete aggregate processing plants for quarries throughout the UK and northern Europe.

As part of its contract with the New Cliffe and Olde Cliff quarries, the company also supplied a complete washing plant for the reprocessing of mill waste.

Tony Lidbetter is the Whitwick representative on site at the quarries.

Commenting on the scale of the conveyor system, he said that: "The challenge of designing and installing an elevated conveyor system in such a long tunnel was demanding but our design has proved completely successful".

"Of course, in the industries that we serve reliability is all-important, that's why we chose Sumitomo/WEG drive systems for the conveyor".

"We have used a lot of Sumitomo equipment on our projects and the reliability and service have always been excellent, so we would have used this equipment anyway, if it had not been already been specified by MQP".

Ian Conway, Company Engineering Manager for MQP agrees with Lidbetter's comments.

"The decision to use Sumitomo gearboxes was fairly easy", he said.

"They offer extreme durability and reliability which are vitally important as in our operations - we are one of the five busiest quarries in the UK - we cannot afford breakdowns".

"Over the last few years, Sumitomo has become our preferred supplier of gearboxes: we already had a number of Sumitomo gearboxes in New Cliffe Hill quarry and have found the performance and backup to be exceptional".

"We also benefit from commonality of spares and the fact that Sumitomo holds larger spares locally; however, we have had no requirement to call on them as yet".

The Sumitomo/WEG drive systems used on the conveyor were supplied assembled by Sumitomo to Whitwick Engineering as packaged drive systems built onto a baseplate.

In total there are six of these units: four single drive units, each comprising a Paramax gearbox and a WEG premium efficiency motor of 132 and 160kW, respectively, and two of 200kW rating.

In addition, a further pair of WEG 200kW motors and Sumitomo gearboxes drives a single inclined conveyor.

The Sumitomo/WEG combination is ideal for demanding quarrying applications, allying high performance and reliability with high levels of efficiency.

The Paramax gearboxes are bevel helical units having a 25 degree pressure angle on their gears, which provides greater tooth strength making them suitable for high overloads.

In addition, the increased helix angle integrated into Paramax design gives a greater number of teeth in contact for higher performance and reliability with reduced noise levels.

WEG's W21 line of Top Premium Efficiency motors complement the operation of the Sumitomo gearboxes.

They exceed all CEMEP requirements for energy efficiency, enabling MQP to benefit from the highest levels of energy saving on what are very large motors.

In addition, the W21 design features sturdy cast iron frames, IP55 rated (IP65 optional) against the effects of dust and ingress from water jets.

It also includes such features as V-rings on both motor end shields, anticondensation drain holes and thermal protection via thermistors (one per phase) on frame sizes 160M and above.

Back to top