Published in March 2009 Australian Longwall Magazine

Designed by CSIRO Exploration and Mining research scientist Bulent Tiryaki, SDDS was developed for the design and analysis of shearer drums for improved cutting and loading performance.

The software works by plugging in a number of parameters, such as coal seam properties and pick design, and is then used as an engineering tool by mine planning, production and maintenance engineers, as well as OEMs, to select and design equipment, and predict performance in a changing environment.

“Past studies indicate that face equipment failures are responsible for over a quarter of the lost production time in Australian underground coal mines and shearer-related failures account for up to 40 per cent of the total downtime in face-equipment breakdowns. The progressive damage caused by cutting forces, bending moments and vibrations is a significant cause of shearer failures,” Tiryaki said.

“Coal loading is also another problem in longwall mining which can cause a considerable amount of coal left unloaded on the shearer track, which necessitates extra flitting runs and raise problems in pushing the face conveyor towards the coalface reducing the production rate of the longwall,” he said.

Tiryaki said SDDS is believed to lead to a significant improvement in shearer availability.

“SDDS can predict these forces, moments and vibrations, as well as the loading ability of the drum, for different shearer drum designs, operating conditions and coal properties.”

He added improvements in shearer reliability would reduce unscheduled breakdown maintenance and facilitate better planned and safer maintenance activities for the Australian coal mining industry.

SDDS calculations are based on data entered by the user, such as structural features of the shearer drum, coal seam properties, coal cuttability characteristics, pick design and operation parameters, pick lacing parameters and shearer operational conditions.

The software can be used during initial mine planning to select the type and model of shearer, cutter drive and ranging arm and predict the effects of changes to the combination of input parameters on cutting and loading performance of the shearer.

Once the mine is operational, SDDS can be used to predict the effects of parameter changes such as haulage speed, web thickness, drum revs per minute, excavation height, cutting mode, pick design and operation parameters, and coal properties on the cutting and loading performance of the shearer.

The software can also be used to optimise pick-lacing arrangement by determining the fluctuations in pick and reaction forces, pick-tip bending moments, and drum torque.

To optimise loading performance of the drum, SDDS calculates the filling factor and conveying ratio for the drum so the designer can notice if the drum is likely to be clogged, overfilled or underutilised when in operation under the given design and operation parameters.

The software can also be used to predict pick consumption rate and field-specific energy as well as checking the prescribed limits of a shearer will not be exceeded under different operating conditions.

Like mine operators, OEMs can also find benefits in SDDS. When designing for a new longwall project, OEMs can use the software in equipmentselection; find optimum pick-lacing for good drum balance and efficient cutting; and design shearer-drum structural properties for optimum loading performance of the drum.

For an operating longwall mine, OEMs can also use SDDS for optimisation of the pick-lacing and drum structural properties for improved cutting and loading performance.

The software can also be used to predict whether the shearer will exceed prescribed limits under different conditions.

“A proper shearer drum design developed based on SDDS outcomes for a longwall operation also reduces the loading on cutting and haulage units of the shearer,” Tiryaki said, noting this reduced costly and time-consuming downtimes and resulting repairs at OEM workshops.

SDDS is yet to be trialled in situ, particularly the coal loading module, however, pick-and-ranging arm-force models have been tested at underground trials at the Beltana mine and during Tiryaki’s PhD studies in Turkey.

“Further underground trials are needed to establish accurate correlations between cutting power consumption, ranging arm forces, operational parameters of the shearer and coal properties in order to reach pick-and-ranging arm-force models that are applicable to all Australian longwalls,” Tiryaki said.

“Theoretical approaches behind the coal loading, conveying and spillage-rate models in SDDS also need validation through theoretical and practical studies on different longwall shearers working under different geomechanical conditions in Australia.”

Tiryaki said in-kind support from Australian longwall mines was needed to conduct these practical trials.