Battery-powered hauler technology moving forward

AS THE demands for longwall mining increase exponentially, more fluid processes in development are becoming crucial. One focus has been the development of battery-powered coal haulers, with Odenburg Group and Peabody’s Energy Harris mine leading the way.

Donna Schmidt

Published in the August 2005 American Longwall Magazine

Dennis Richards, Peabody maintenance director (eastern US and Twentymile mine), and Steve Rudinec, Odenburg vice president of engineering, detailed current and upcoming technologies as well as the successes the technology has enjoyed at Pittsburgh’s National Coal Show in June.

A battery-powered coal hauler is a miner hauler equipped with rubber tires that mechanically loads its bed, then discharges the load to a feeder breaker or belt. Richards and Rudinec outlined the dimensions and performance improvements of three Oldenburg Stamler BH20A haulers and four Oldenburg Stamler BH20Ls.

The battery is the first of the hauler’s three main sections, which at 128 or 140V and minimal size, allows for control of the machine while still having room for an operator’s control station and compartment, an electric motor and associated controls and mechanical drives to assist in traction. The center section, consisting of a connector between the front and rear of the machine, gives it prime steering and vertical articulation.

The third and final section of the hauler is comprised of the trailer, or bucket, which can be loaded and unloaded via a ‘moving assembly’ and can carry coal on a payload bed. The moving assembly on this piece is a loading and ejector assembly in the rear of the trailer that is operated with hydraulics and works in conjunction with the continuous miner for optimum loading efficiency; wing-shaped, fitted sideboards and tailgate aid in this by allowing for maximum ‘heaped’ capacity.

The BH20 cars, which Richards and Rudinec concentrated on when investigating successful outcomes, are 10ft wide x 4ft high x 37ft long and have a capacity of 20 tons. Configured with two 40hp DC series traction motors and a 10.5hp pump motor, this powerful machine can turn in a 17ft-wide entry.

Richards and Rudinec’s study of the seven BH20 haulers took them to Peabody’s Energy Harris mine, which runs three per development section, each carrying between 13 and 15 tons of coal per load. With a seam height of 78in, the operation’s average rate of advance is 325 linear feet daily based on two shifts.

The development cross cut centers are 80ft x 140ft for the first two entries and 100ft x 140ft for the third, and given favourable conditions the gate ends can be driven more than 800 linear feet. These haulers fit the operation well, averaging 99% over the last two years.

Peabody and the Oldenburg Group collaborated in 1999 on an endeavor that would hopefully make battery change-out times quicker and would make the process simpler and easier to accomplish. They found success with the development of the battery carousel, or turntable, concept.

With an 1500-amp hour battery placed on each arm of the carousel, the tray rotates so the second battery in line can take over, while the spent unit is unloaded and a new one added in its place – all while being powered by the expiring battery unit and with a total changing time of about five minutes. Having two on board at once also eliminated the need for additional charging stations, they said.

The station is also mobile, able to be unbolted from its location, collapsed, and loaded on to a hauler and it transported to a new location if needed.

Another innovation the Peabody/Oldenburg team has worked on over the years is a simplification of coal hauler controls. The Oldenburg ‘Contractorless’ drive, which had its inaugural use at the energy company’s mine, replaced DC-directional contractors with solid state IGBTs.

Now the unit includes a microprocessor, allowing for value-added diagnostics and digital control. The real-time advisory panel was developed to inform the operators of de-energising situations, including an emergency-stop depression, a ground fault, dangerously high temperatures or incorrect switch positions. The panel also possesses a data logger that delivers a ‘snapshot’ of the machine’s performance over time.

With these advances have come increased horsepower for maximum efficiency for the system and a lighter battery hauler, in response to FEA standards. Now made of non-metallic, lightweight composite materials such as nylatron, the system can be even more efficient to use without compromising the design of the unit.

Even with the large strides the Peabody/Oldenburg team has made recently in hauler technology, the innovations being developed for the machine haven’t stopped. One up-and-coming release, according to Richards and Rudinec, is the Oldenburg BHAC mineral hauler, a battery-powered unit that uses AC-induction XP Oldenburg motors. The motors are wound with inverter duty Q wire and are tested at high speeds and temperatures, and the exclusively owned drives require a 240Vdc input voltage.

The design advantages for BHAC include the exclusion of the brushes and maintenance for the DC motor as well as constant torque for the haulers to operate within, but in place of the DC motors there is potential for increased horsepower to be installed. The speed of the pump motor can also be stabilised as it could be with the DC. All in all, they said, this new technological page for haulers equates to a reduced expense for motor restorations and increased power for hauling, leading to improved cycle times and increased load numbers.

Another vital innovation is regenerative braking, a feature that allows for a 3% increase in battery life through the process of returning a small amount of energy to the battery without the fear of hydrogen emission. While the percentage may seem insignificant, Richards and Rudinec note that this option is much more effective for conservation than the alternative – heat loss and wasted power. The technology, which requires MSHA review, may be utilised later as an optional addition to digital DC power drives and new AC drives.

While this area of technology is rapidly advancing, more up-and-coming innovations such as fuel cell typology, new batteries such as NiMH, and diesel-powered hauler technologies are keeping the Oldenburg R&D department on the move. Together with Peabody, they have placed over 90 battery haulers into operation, with many still to be delivered.

“With the introduction of new technologies, we anticipate more battery haulers placed at Peabody Energy’s operations as well as other major coal producers around the world who struggle to keep development sections up to speed with the longwall’s increasingly growing rates.”

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