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