Tough environmental conditions at Mt Thorley Warkworth coal preparation plant is no match for Bürkert engineering. Gritty black dust is unavoidable at coal processing operations. Coal mining, transport and preparation is one of the dirtier mining applications around. The black gritty coal dust gets into everything, clogging up pipes, mechanical parts, and really everything that is not specially engineered for such a demanding environment.
One company that has an effective means of suppressing the dust associated with coal processing and transportation, and avoiding the operational and OH&S issues that can result, is process control expert Bürkert Fluid Control Systems.
Bürkert has considerable experience working in dirty, hazardous and aggressive environments, and has engineered a selection of products for difficult applications. Moreover, Bürkert has the process control and pneumatic experience to integrate with existing site systems and infrastructure.
Even Bürkert’s dirty environment capability was tested by the more extreme conditions found at the Mt Thorley Warkworth coal mining operation. More than 9 million tonnes per annum (Mtpa) of feed coal is mined at the Mt Thorley Warkworth operation and delivered to the Coal Preparation Plant, where it is off-loaded into the dump hoppers. Processing yields 5.8 Mtpa of salable coal.
The coal from each dump hopper is fed into rotary sizers, and finally onto raw coal conveyors for delivery to the process plant. Due to the movement of considerable volumes of coal, dust suppression in these areas is critical, and is achieved by wetting coal with water. This water is recycled and reused.
In the past, pipes, valves and solenoid valves (actuated with water) were clogged with scale due to poor water integrity, voiding the dust suppression system. These faults occurred approximately once per month on each solenoid valve, necessitating removal of the coil in order to clean the blocked wetted (internal) parts of the pilot valve.
Each valve would take about 30 mins to clean, and including the time to travel to the valve site and multiply it by the number of valves on site at Mt Thorley Warkworth, adds up to a considerable maintenance liability. The site was planned to be completely switched over to a 24 Volt standard, for safety.
The local Bürkert representative looked at the problem and considered what would be the option. The Bürkert representative suggested the 2000 series angle seat valve, pneumatic actuated, with the closed coupled series 331 solenoid valve, which is suitable for occasional water laden pneumatics.
Where possible, an arrangement involving multiple solenoid valve pilot valves with pneumatic conditioning, securely cased within a custom-designed stainless steel enclosure was used. The enclosure design included a sloping roof to reduce coal dust contamination. Mt Thorley Warkworth and Bürkert started replacing old valves two years ago, and have never had to service one of them.
The Bürkert valves on the coal feeder dust suppression system have been in use for two years now, with no failures from the production side.
The second ROM [Run Of Mill] dust suppression system was commissioned with the 2000 series Bürkert angle seat valves and the 311 solenoid valves. The system has been operational for 12 months, and despite the challenging conditions there are no problems.
The air and water lines of the dust suppression system are connected to PLCs, which are controlled via SCADA for complete automation of the dust suppression system. The Bürkert valves were patched into an existing site network topography, to minimise hardware costs. For example, when trucks reverse to the coal delivery bin hoppers at the preparation plant, sensors note the truck presence in the delivery bay and initiate the dust suppression water flows.
The dust suppression system solution would be applicable to the vast majority of Australian mine sites, and with current safety trends in the industry, now is a good time to start planning for mining site safety improvements.
The resources boom and higher mineral export prices have encouraged all mining-related facilities to push existing infrastructure and resource capacities to the limit. More shifts, more hours, higher volumes and more by-product. Bürkert has even been involved with some mines, to increase efficiencies and outputs via automation of conveying and other applications.
Bürkert not only has a selection of standard products to work with, but also the engineering experience and expertise that allows to make sure Bürkert finds the solution. And the follow up service and support infrastructure to make sure the user are not alone if and when problems do arise.