Pempek has developed a unique electronic control system package for the control, monitoring and semi-automation of roof drilling/bolting rigs used in gaseous underground mining environments.
Designed for easy installation on new and existing mobile mining machinery, the system is composed of a drill rig-mounted, flameproof, hydraulic-electric control module (“E-Box”) and a companion flameproof, push-button Human-Machine Interface (“HMI”) user control station (Figure 1). The E-box module can be readily adapted to suit roof drill rig models from several different manufacturers, e.g. Sandvik 2500 Series or Joy HFX.
The system provides a number of benefits over traditional roof drill controls; including:
- 1. Clean, simple installation
- 2. Smooth, electronic drilling control
- 3. Flameproof-certified (EX d) system
- 4. Advanced diagnostics
- 5. Increased safety
- 6. Built-in roof mapping
- 7. Lower maintenance and life-cycle costs
Figure 1 – Pempek E-Box Push-Button Drilling System
This paper introduces the roof drilling and bolting control system and how it benefits mining operations for the improvement of safety, productivity and maintenance.
Drill rigs for mobile mining platforms are typically constructed from hydraulic cylinders, motors and actuators. Traditionally, a large set of hydraulic hoses is connected between the body of the drill rig and a hydraulic switching valve bank (Figure 2). The valves controlling flow to the drill rig functions are then either controlled by hand levers of by a remotely located control system.
Figure 2 - Traditional Rig (many hoses, modules)
Pempek’s approach is very different. The E-Box combines hydraulic valves, solenoids, sensors and electronics into a single, flameproof-certified package. The unit attaches directly to the mast of the drill rig – via a hydraulic adaptor plate (Figure 3). This cleaner assembly does away with up to 30 hoses; depending on the make and model of drill rig. Some hydraulic hoses are still required to provide fluid power to the E-Box module as well connections to the drill head unit of the drill rig.
Figure 3 - E-Box Installed on Drill Rig
The HMI Control Station (Figure 4) is a flameproof-certified operator panel complete with function push-buttons and integrated graphics display. A simple power and data cable connects the HMI station to the E-Box. The operator uses the HMI station to control and monitor all drilling and bolting functions.
The roof drilling system significantly improves the comfort and safety of mine workers in three ways:
- 1. Reduction of hand and arm strain injuries
- 2. Prevention of unplanned rig movement
- 3. Roof Strata Mapping (predict roof weakness)
A common safety concern with traditional roof drilling machines is repetitive type strain injuries. Workers often suffer these injuries through repeated handling of hydraulic control levers (Figure 5). Injuries arise from the need to use awkward hand/arm positions to manipulate the levers.
Figure 5 - Manual Hydraulic Levers
The use of a push-button control system (Figure 6) does away with the injuries associated with long term handling of hydraulic levers throughout a working shift that can last up to several hours.
Unplanned Drill Rig Movement
Drill rig parts can move rapidly, driven by electric and hydraulic motors and actuators. Physical damage or system failure can cause the machine movements to occur without warning. A so-called unplanned movement places operators at risk of serious injury or death.
Figure 6 - Push-button Control Reduces Injuries
The Pempek drill rig control system mitigates the risk of unplanned drill rig movement events by implementing a design that is consistent with IEC61508 (International standard for functional safety of programmable systems). Safety features have been designed into the product to greatly reduce the likelihood of an unplanned movement due to electronic failure and also to shutdown the hydraulic power source (pump) if an unplanned hydraulic movement is detected (e.g. stuck spool valve).
Roof Strata Mapping
Roof bolting is a technique used by mine engineers to prevent roof falls in underground mining. Based on studies of the geology, engineering staff make decisions about the best way to support the roof and prevent tunnel collapse. This translates into a specific plan for bolting patterns and other roof support strategies.
Although roof control has developed into a reliable and precise science, accidents can and do still occur when the roof geology changes unexpectedly. This typically requires the addition of more bolts or other measures to ensure that a roof fall does not occur.
The Pempek drill rig control system measures roof strata hardness distribution while drilling each bolting hole. The system collates measurements to construct a spectrographic roof map of strata hardness (Figure 7).
Figure 7 - Roof Mapping Display
The map indicates the hardness of the roof strata at varying drilling depths using a colour-coded scale. The map appears on the main screen of the HMI so workers can quickly assess the roof conditions at any time. This information quickly reveals if the roof is weak and additional bolting or support is required. The system can also generate an alarm to alert mine personnel of unstable roof conditions that could result in an imminent roof fall.
In recent years, the increasing use of electronic control and automation has enabled enormous productivity gains across many industries. The Pempek drill rig control system provides a similar advantage in drilling and bolting productivity through push button control and automated features. The system empowers operators to achieve drilling and bolting cycle times up to 15% faster than with previous technology.
With drilling and bolting functions of the drill rigs under the control of an intelligent, computer-controlled system; all drilling, roof mapping and maintenance data is continuously logged. Pempek has several methods by which the data can be retrieved from the machine and used for reporting and analysis.
The Pempek drill rig control system features fewer parts, cables and hydraulic hoses when compared to a traditional approach. This automatically translates into lower cost for installation as well as reduced maintenance requirements.
By integrating all hydraulic and electronic control functions into one system, a very advanced level of diagnostic monitoring is possible.
Figure 8 - E-Box Installed on Bolter Miner
The Pempek roof drilling system is the perfect solution for mobile mining equipment where roof drilling and bolting is required.
A common application is roof drilling rigs on a bolter miner (Figure 8). The bolter miner combines a continuous drum-type miner with continuous semi-automatic roof drilling and bolting. The platform provides rapid roadway development with a single machine; replacing the traditional concept of two machines – a miner and a separate mobile bolter platform.
A typical bolter miner machine is fitted with four (4) roof bolting rigs; mounted in a row directly behind the cutter drum (Figure 9). Installation of Pempek push-button drilling is as simple as fitting each drill rig with its own E-Box and then installing a dedicated HMI for each drill rig to be controlled. A master processor is then installed in the main enclosure and is connected to each HMI station.
The simplicity of the system allows it to be easily integrated into a new machine during manufacture, or into an existing machine – at time of overhaul.
Figure 9 - Typical Bolter Miner (Push-button Drilling Installation)