Quarry Plant Efficiency

The downturn in the construction industry and soaring fuel prices are forcing quarry firms to look at all aspects of production to see where costs can be reduced. Karen Wilde offers an overview of some of the plant advances that are helping firms relieve the burden of riding out the credit crunch and the role of efficient plant layout in cutting costs.

With commentators predicting the downturn could last until 2010, many quarry firms are looking closely at plant to help them through the lean times. Greater plant efficiency can lead to lower fuel and oil costs, while better access to maintenance areas can save time and increase automation to save on labour.

When it comes to lowering mobile plant fuel use there is a range of technology beating a path to greater efficiency. Liebherr’s 2plus2 is a good example of this. It claims its hydrostatic driveline – used on its wheeled loaders – can bring a 25% reduction in fuel consumption.

This can save operators around £38,000 over a 10,000hour period and reduce CO2 emissions by 300tonnes over the period – and in a new development for 2008 Liebherr has speeded up the process for changing hydraulic attachments for its excavators with the Likufix quick change system, offering a productivity boost.

Another fuel-saving device comes from Caterpillar in the form of Engine Idle Management System (EIMS) on its H-series wheeled loaders. Rather than idling away using fuel the loader has a hibernate facility when the machine is in neutral and has the parking brake on, cutting an all important few percentage points off fuel use.

Volvo has also been tackling the idling issue in the quarrying industry. It isseeking to use its new hybrid engine, first seen at Bauma last year, as a source of cab power during idling. This means the engine can be switched off and not effect functions such as climate control.

This year at Conexpo, Volvo introduced the L220F hydrostatic wheeled loader, which the firm says could offer up to a 10% reduction in fuel consumption. However,a hybrid wheeled loader – probably the 30tonne L240F – won’t be available in the UK until next year.

But it is not just the plant that can save a company money in terms of reducing fuel consumption. One area often overlooked is the operator. The way in which an item of plant is driven is as important as the engine itself

The Safe and Fuel Efficient Driving (SAFED) scheme has an Aggregates Levy Sustainability Fund pot of £850,000 and it offers aggregates related firms access to getting drivers trained. LMS, which runs the scheme, is also looking into a yellow plant version of SAFED.

Companies have to prove aggregates make up 50% of vehicle mileage or their business base to apply, while the programme also demands a £50 a driver fee for firms employing up to 250 people, rising to £100 for larger companies.

Julie Welch, Cemex health and safety manager for logistics says of the scheme: “In the current climate and with the fuel price at its highest all savings are welcomed and with the SAFED scheme, it’s a winwin situation.

“With fuel savings of approx 10% and gear change reduction of over 40%, the company would be foolish not to continue. This is over and above the associated savings which are more difficult to define, such as wear and tear, tyres etc.” Phone 0845 450 7373 for more on SAFED.

Other ways of saving money include cutting off plant problems before they arise. Examples of this are Komatsu’s Komtrax and JCB’s LiveLink, which provide the operator with a high-tech system that can increase efficiency, improve productivity and enhance the servicing process.

These systems allow operators to monitor the health of their fleet remotely with the introduction of sensors at critical points that save money on costly repairs by giving an early warning of potential problems with oil pressure and water temperature among others.

Then, of course, there is the option of exchanging one item of plant for another. Moving material from the rock face to the processing plant or from the processing plant out from the quarry floor can involve a fleet of loaders and trucks and the associated labour, fuel, oil and maintenance costs.

An alternative to this – used at Tarmac’s Swinden Quarry and Ennstone’s Cloud Hill Quarry, for example – is to use conveyors. Telestack’s TransTrack Link conveying system is an example product with the TT-1043 achieving transfer rates as high as 1,000tph with a belt speed of 1.7m per second.

Linked in a series to move material from the primary crusher on the quarry floor to processing machinery, or to a fixed field conveyor, link conveyors remove the need for trucks and associated costs and increase the environmental performance of the quarry by reducing noise, dust and CO2 emissions. The reduction in truck movements also creates a safer working environment.

Using a form of radial conveying technology can increase quarry performance by reducing stockpile segregation, degradation and contamination. Loader formed stockpiles increase the riskof producing a contaminated product and while stockpiling with a wheeled loader can decrease the risk of segregation – common in conical stockpiles as the momentum of larger particles carries them to the bottom of the pile – this does rely on the loader driver blending material within the stockpile to maintain consistency.

Changing the quarry layout and using a telescopic radial conveyor to stockpile in windrows increases the quality of the product, reduces labour, fuel, oil and maintenance costs, achieves tonnages of up to 2,000tph and increases stockpiling capability by 30% when compared with conical stockpiles.

Finally, combining processing and handling machinery together can also have a big effect on the efficiency of the quarry operations and the bottom line. This has been the experience of Barry Wood Plant Hire in Derbyshire at his limestone operation. Wood experienced increased downtime in his limestone quarry because he had to re-position his excavator, primary crusher, screen and secondary crusher almost daily. Product stockpiles around the screen needed to be moved along with the machinery and the secondary crusher needed to be levelled on the ramp – all of which cost valuable processing time.

By adding a telescopic conveyor he engineered a situation where only the primary crusher and excavator needed to be moved. The conveyor is used to link the primary crusher to the hopper of a re-circulating screen.

The result is that all the stockpiles can stay in the same position for around a week at a time. The conveyor has increased the processing time and reduced the downtime for re-positioning between blasts. The new layout now achieves 400tph on 100mm down.

Wood: “The tracked telescopic advantage of the conveyor has been the key for us here. Tonnages have increased and we now have the flexibility within the quarry to process 50% of a blast in one movement.”