August 15, 2006

DIRTY DUST SUPPRESSION SUCCESS GIVES REAL MAINTENANCE SAVINGS

Gritty black dust is unavoidable at coal processing operations. 

Caption: Mt Warkworth Thorley Coal Preparation plant.

Mr Ged Mungoven, Coal Preparation Plant Maintenance Supervisor at Coal & Allied's Mt Thorley Warkworth Mine, said that coal mining, transport and preparation is one of the dirtier mining applications around - and that is saying something.

"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.

Bürkert 2000 process valves and 331 pneumatic pilot valves at work at Mt Thorley Warkworth.

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," said Mr Mungoven.  "You include the time to travel to the valve site and multiply it by the number of valves we have on site at Mt Thorley Warkworth, and it adds up to a considerable maintenance liability.

Bürkert SS enclosure at Mt Thorley Warkworth.  [Right] Enclosure is dirty and dusty due to the environment.  [Left] Inside the enclosure, however, is clean and the products protected, enhancing service life and reducing maintenance.

"Furthermore, we were keen to get the site completely switched over to a 24 Volt standard, for safety.

"The local Bürkert representative, Keith Dumbrill, looked at our problem and considered what would be the best option.  Keith 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, we used an arrangement involving multiple solenoid valve pilot valves with pneumatic conditioning, securely cased within a custom-designed stainless steel enclosure.  The enclosure design included a sloping roof to reduce coal dust contamination," he said.

"We started replacing old valves two years ago, and have never had to service one of them.  100% uptime, 100% success and - so far - no maintenance.

"That frees up my teams' time, which is a real saving."

Dayshift Maintenance Electrician Mr Colin Bagnall at Mt Thorley Warkworth - responsible for installing, monitoring and ensuring optimum system uptime - agrees.

"We have been using the Bürkert valves on the coal feeder dust suppression system for two years now, with no failures from the production side. 

[Above] Coal dump site at the Mt Thorley Warkworth coal washery - art of the second ROM dust suppression system installed at this site.  Including flow meter [below].

"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 we have experienced no problems," said Mr Bagnall.

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 Bürkert solution for our dust suppression flows is one of the most reliable systems I have seen," said Mr Mungoven.  "Dust suppression is a hot issue in mining right now, and the Bürkert solution is quick, effective and good value.

"The more we look around Mt Thorley Warkworth, the more places we see to install the dust suppression system.  And with Bürkert, we can be confident that it will do the job without adding to my workload."

With a considerable OH&S concern apropos the breathing of silica (a component of coal dust) and the development of silicosis and the potential for employee legal claims, dust suppression has never been such a hot topic for mine sites. 

Local Hunter Valley and Newcastle Bürkert representative Mr Keith Dumbrill said that 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 our 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. 

Coal holding and transport at the Mt Thorley Warkworth coal washery.

"But in the process of increasing output, you need to make sure that there is not an increase in unfortunate side effects - or that, if there are, you address these like Mt Thorley Warkworth has. 

The Operations and Projects teams at Bürkert worked together with Mr Dumbrill to ensure the best and most effective solution was suggested. 

"It is this type of involvement and thinking outside the square that you can expect when you deal with Bürkert," said Managing Director Chris Hoey.

"At Bürkert, we not only have a selection of standard products to work with, but also the engineering experience and expertise that allows us to make sure we find the best solution for you.  And the follow up service and support infrastructure to make sure you are not alone if and when problems do arise."

"Although up-front valve cost is a large consideration, how the product and company will perform once there is a problem is a major test of the reliability of that product.  If you contact us with an issue, Bürkert works to make sure you get your systems back up asap and minimise costly downtime," said Mr Hoey.

With a global network spanning offices in more than 40 countries, and operational outposts in an additional 80, Bürkert Fluid Control Systems is an established and mature global organisation celebrating its 60th Anniversary in 2006.