MECHANISED COAL
full time access to safety management systems, engineering drawings, real time monitoring of equipment and Target Action Response Plans being immediately initiated upon a change in data points.
Spin to stall
Anglo American also realised there was an opportunity to introduce an alternative roof bolt installation technique called‘ spin to stall’ in Australia. Spin to stall was first introduced in Anglo American Coal in South Africa where it has been successfully used for over a decade, though implementation of South African spin to stall resin in Australia has proven to be near impossible due to a significant difference in geotechnical conditions, mining method, and, subsequently, roof bolting equipment. Therefore, a new spin to stall development project was initiated between Anglo American Coal and Jennmar Australia( SPIN2STALL ®). Successful implementation of spin to stall( STS) has been achieved at Grasstree mine.
In the presentation Development and Implementation of the“ Spin to Stall” Resin Bolting System at Anglo American’ s Australian Underground Coal Operations at the 34th International Conference on Ground Control in Mining, authors Jason Emery et al noted that“ in order for the [ longwall ] development process to be more efficient, continuous miners must operate for longer and or cut at an increased rate. The rock bolting process is a key constraint to increasing development cutting rates, particularly at the beginning of a pillar cycle. It was recognised at Anglo American that extended hold times, while appearing insignificant individually, can result in considerable productivity delays when accumulated over a panel. In addition, conventional resin and rock bolting processes were recognised as being susceptible to human error during the installation process. Among other shortcomings, failure to adhere to correct spin and hold( SAH) times can potentially damage the resin bond and, hence, load transfer capacity of the system; this process is completely reliant on the operator. Hold times, to allow the resin to set, are also known to fluctuate seasonally with temperature. Therefore, in an attempt to decrease the bolting constraints in the development process and, at the same time increase bolt installation consistency, in late 2010, Anglo American approached Jennmar and J- Lok Australia with a view to develop a STS resin bolting system suitable for Australian ground conditions, mining methods, and equipment.”
The STS resin roof bolting system has been successfully implemented in Australian geotechnical conditions using continuous miners with in-place bolting rigs. The Jennmar and J-Lok SPIN2STALL involves a complex and demanding relationship between the correct resin properties( catalyst type, catalyst concentration, filler grade, and viscosity), bolt properties( profile and breakout torque), and drill rig properties( rotation, thrust, and torque).
Roof bolts were installed using a Joy 12CM30 continuous miner with in-place two speed rotation unit( TSRU) HFX bolting rigs on either side( i. e., four roof bolter rigs). Although not limited to the modern TSRU rotation unit, it is complimentary to the STS system. The intuitive kick-down function in the TSRU essentially allows an additional one to two seconds cure time prior to stall, and, hence, higher levels of pretension can be successfully applied without damaging the curing resin bond(> 400 Nm).
“ As applied at Grasstree, the STS system represents an incremental productivity improvement and a step-change in support installation quality. While the industry still searches for productivity improvements in bolt installation, the STS system can essentially be implemented at minesites within a relatively short time frame and at minimal cost. Elimination of hold time in the resin / roof bolt system opens more doors for further automation of the bolting cycle, particularly with the arrival of electronically controlled in-place drill rigs. While not the case with conventional resin encapsulated roof bolts, the STS system ensures critical parameters are within a specified range to achieve correct installation( i. e., the system is self-auditing). Increasing support installation consistency is regarded as another step towards achieving zero harm in the workplace.”
Longwall moves
Signal Peak Energy’ s Pre-Developed Longwall Recovery Room was presented by Brad Hanson, CEO, Signal Peak Energy at Longwall USA 2015. His company has developed a greenfield coal mine into one of the largest single longwall producers in the USA. He reported that“ longwall recovery history was made at the mine in late January of 2014 by successfully mining into and recovering the longwall in a pre-developed recovery entry. This longwall recovery fulfilled the Signal Peak vision to safely advance the longwall into a pre-developed recovery room without the need to stop and install any supplemental roof support.” Unlike other pre-driven recovery rooms, the 42 ft( 12.8 m) wide recovery room was driven in two equally wide phases.“ This entry was bolted, meshed, and then completely backfilled with a specially formulated, cuttable, low density concrete.”
Ampcontrol is an industry leader in longwall electrical packages up to 7.5 MVA. All its customised integrated longwall systems are fully supported by experienced certified experts, including longwall moves.
The company’ s experience and expertise in longwall solutions extends to longwall moves conducted by its specialist technical support teams. Its longwall move electrical system solutions commence with pre-move SIL AS2290.1 auditing and reporting is then conducted during move phases. The single contact point project management and coordination includes fault finding, engineering consultancy, production scheduling, repairs and preventative and predictive maintenance on all equipment indicated from the audit to full install, commissioning and ongoing operational production support.
The move solutions cover a range of longwall equipment including substations, development centres, DCBs, pump starter DCBs, HV cables, protection, monitoring and control or lighting equipment.
Shield supports
Increasingly deeper mining and ever lengthening faces require greater performance from the shields. Increasing hydraulic pressures and cylinder diameters are the result. As longwall systems perform at faster speeds, so the changing loads in the hydraulic system are intensified. One of the central requirements is that the plunger pumps and / or the hydraulic stations deliver the necessary volume flow of hydraulic emulsion at the required pressure reliably and with a high level of availability.
KAMAT offers a wide spectrum of performance classes of plunger pumps, so that the ideal pump can be found for every project.“ In mining water hydraulics is used, where an emulsion with a low additive percent in the water is employed as lubrication for the hydraulic cylinders. Since the KAMAT plunger pumps are designed for the pumping of pure water, the lubrication through the pumped emulsions offers a considerable service life advantage.”
KAMAT plunger pumps are extremely rugged and simple to repair, if required. A great advantage in this regard is the modular component system, with which relevant pump parts of different construction series are identical and are thus simple to replace. This means simplification and flexibility in maintenance and repair.
KAMAT high-pressure pumps are used in central hydraulic stations which supply complete mines, as well as stations in proximity to the face which supply the face with the necessary hydraulic fluid. These stations can be on rails, on chains, on wheels or suspended in the assembled monorail car. For reasons of space, the pumps are arranged in-part vertically.
The pumps typically employed in mining are at power levels from 132 to 500 kW. KAMAT supplies single pump units up to 800 kW and the installed power consumption of an entire station can be
138 International Mining | SEPTEMBER 2016