Putting clean air technology first 22 Nov 2018

Roger Murrow reporting for TunnelTalk
Many things are affecting tunnelling but what is becoming more prevalent is the development of clean air technology. This takes in many things, including new low emission engines from the likes of Caterpillar and Deutz (amongst others) and the ability of equipment to work from generator or mains electricity. However, that is not all as many manufacturers are developing clean air solutions that are making technology not just an afterthought, but rather a core feature of the equipment.

Zero emissions underground

Two of the major equipment manufacturers have certainly taken the clean air mantra to heart. Epiroc for one has stated that its aim is to provide zero emission equipment for all its underground operations with a focus on battery-driven machinery. The company has focused its development on zero-emission and battery-driven machinery, and recently launched it’s second generation electric battery machines.

“We are leading the charge towards sustainability in mining through battery electric, zero-emission equipment,” says Stevan Topalovic, Vice President Marketing Underground Rock Excavation division at Epiroc. “We proudly present our second generation electric battery 14 and 18-tonne loaders, our 42-tonne truck and our mid-sized drilling family including face drilling, production drilling and rock reinforcement rigs.”

Latest battery-driven machines from Epiroc
Latest battery-driven machines from Epiroc

“The mine of the future is carbon-dioxide-free, digitalised and autonomous. This requires new control systems, improved equipment as well as efficient management systems that meet future demands for a sustainable industry,” says Anders Hedqvist, Vice President of R&D in the Epiroc Underground Rock Excavation division at Epiroc. “Today, our selected key partners on site will see presentations of our new battery-driven rigs and learn about our new battery service offering. In our innovation arena, the new Control Tower, we will also demonstrate advanced automation solutions and discuss strategies towards safer, more productive operations.”

Epiroc sees electric and battery-powered vehicles as the future in underground equipment. As well as the lower running cost of the equipment, there are also said to be considerable savings to be had in ventilation and cooling, but the real motivating factor in the development of the equipment is that electric machines contribute to a safer and healthier working environment.

Sandvik DD422iE
Sandvik DD422iE

Sandvik Mining and Rock Technology has likewise not been slow to adapt a clean air approach to its latest developments. Battery driven carriers for its DD422iE and DT922iE drilling jumbos now provide zero emissions. Additionally they provide significant reductions in heat generation, are less noisy and there is a tangible reduced risk of fire.

The company has also taken the opportunity to look at the design of the cabin of its latest tunnelling jumbos. These have undergone comprehensive simulations performed for air circulation and dust which has led to the development of an optimized air circulation system which keeps dust at ground level. Continuing the trend, where diesel engines are still vital for its equipment Sandvik states that its diesel engines conform to the latest emission levels (tier4/stage4) which provide up to a 90% reduction in NOx emissions.

Another manufacturer who is not as well-known as the two manufacturers previously mentioned is JH Fletcher. This company is also undertaking massive strides in developing and applying clean air technology for its tunnelling equipment.

JH Fletcher J101 single boom drill jumbo
JH Fletcher J101 single boom drill jumbo

Currently the company offers enclosed operator compartments as an option on all its drilling jumbos, with most being available with an inbuilt air conditioning / heater systems for mobile equipment. The company’s air conditioning/heater system has been purpose designed for enclosed operator cabs, with filters for both recirculated and make-up air using a high efficiency filter. The jumbos may also be equipped with an exhaust purifier, as well as Tier IV engine options.

Amongst its equipment the company also manufacturers a mobile dry scrubber, which is an inde-pendent vehicle, designed to filter air and direct it back out into the main air stream. For its roof bolting equipment, JH Fletcher offers operator air canopies, with air being pulled through a fan, filtered and then pushed down over the breathing zone of the person working beneath the canopy.

Specialist developments

The increasing demand for clean air technology for underground operations has also seen developments from manufacturers whose business is primarily focused on providing technology for a clean working environment.

Englo Global wet dust extractor unit
Englo Global wet dust extractor unit

One such company is Englo (formerly known as Engart Global) which specifically focuses on equipment and services aimed at dust management, primarily in the field of optimising dust extraction equipment and solving dust related problems. One such solution is its wet dust extractor unit. This enables users to maintain the proper air volumes required to alleviate fumes from equipment and to control the dust emissions generated during the tunnelling process. These in effect allow the air exhausted from the tunnel to be free from air-borne particulate while providing better visibility at the tunnel face thereby controlling unhealthy particulate levels in the tunnel operation.

These developments mean not only compliance with increasingly stringent work place regulations – such as the new US silica emissions legislation which came into force in 2017- but also increases productivity by improving visibility and worker conditions.

Robotic developments are now also providing clean air solutions in tunnelling. This is not just in the case of providing equipment to work underground in tasks that may negatively affect human workers, but also in the provision of specialist equipment to minimise or remove contaminated air.

Swedish company Husqvarna seems to be at the forefront of these developments, with a dust re-duction accessory being available for all its DXR robots. The accessory supplies water to the tool (in this case Epiroc breakers) that is sufficient to bind the airborne dust, contributing to a better working environment thus reducing the risk of the operator breathing harmful dust particles. The accessory also provides a more efficient and economical way of working by eliminating auxiliary equipment or extra workers engaged in binding airborne dust.

A dust reduction accessory is available for Husqvarna DXR robots
A dust reduction accessory is available for Husqvarna DXR robots

Additionally the dust reduction kit has a unique and effective water management system. This has been developed as one of the best ways to control dust is by using water, while wet cutting/drilling to bind the dust directly at the source. This does however lead to the production of slurry (excavated rock and water) and in order to remove this Husqvarna has developed a slurry collector which may be attached to a specially developed slurry vac.

The company has also developed a line of dust extractors designed to meet strict emission regulations. These are ideal for tunnelling as they are compact and equipped with one, two or three powerful single-phase electric motors with a separate cooling, capable of running continuously. Husqvarna also states that it now supplies the most advanced and versatile portable air cleaners available on the market, which complement dust and slurry management equipment, as well being ideal for other applications where good air quality is essential.

More in the future?

The above outline some of the developments that have occurred in equipment designed to make tunnelling a safer and healthier place to work. There is little doubt that many of these developments are being driven by the increasing concern of tunnellers for the welfare of workers at the sharp end of tunnelling operations. However, manufacturers are rising to the challenges being presented and are now producing equipment and solutions which will be refined to further improve working conditions.


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