Until now, the Morton Salt mine operated as a drill and blast, room and pillar mine, mining hard salt deposits at depths of about 2000 feet. The salt is destined for de-icing of roads. To increase production rates the mine decided to convert to continuous mining methods.

A Joy Mining Machinery 12HM36 series miner was delivered to the mine recently and once in full production will work with Joy’s newest 23 tonne payload battery hauler.

The 12HM36 is a continuing development of Joy's 12HM26 and 12CM27 series, which is intended for hard cutting conditions, hence the HM (“Heavy” Miner) designation, said Mike Adamczyk, Joy vice president, global engineering.

The features of this machine are high voltage (either 2.3 kV @ 60 hZ or 3.3kV at 50 hZ) with high installed power, VFD AC traction, JNA microprocessor control system, and a very heavy mass which allows for excellent sumping and cutting rates in hard cutting materials such as salt, trona, gypsum, and potash.

The 25AH27 Articulated Hauler is the company’s latest haulage innovation, designed for long haul distances, high load capacity, or where a mine needs greater mobility than offered by a cable reel driven shuttle car. Joy said at 23 tonnes, the payload of the new Articulated Hauler is the largest available in the industry. This machine is also a continuation of Joy’s established 20AH27 / 1200AH models that have been operating in coal for more than seven years.

The new Articulated Hauler is powered by a 240-volt, 240 kilowatt-hr battery that is recharged while the machine is in operation through the hauler’s regenerative braking system. A unique ground-based battery change out design with a cable take-up allows fast one-person battery changes between shifts.

One of the challenges for the Morton Salt mine was sizing machine components to fit down the small diameter mine shaft, Adamczyk said.

The CM was disassembled on the surface, transported bit by bit down the shaft and reassembled on the pit floor.

In related news, a Joy 12HM36 continuous miner, together with a bridge belt conveyor, recently achieved world class production rates at the Winsford Rock Salt mine in the UK.

According to Joy UK, in June the machine broke continuous miner world salt production records by producing 4,123 tonnes in a single 7 hour production shift. During timed production trials, over 16,000 tonnes were produced at an average of 631 tonnes per hour for all machine (cutting and flitting) operations.

The bridge belt conveyor is 24 metres long hanging off the rear of the continuous miner’s articulating conveyor. This allows a 23 metre overlap with the panel belt and forms a continuous haulage system. The machine has unrestricted movement within the production area allowing the machine to turn through 90o and cut a 10 metre deep “stub” crosscut. These link together with the parallel heading to form full 20 metre ventilation connections.