The Saraji coal mine has benefitted from VEGA’s electronic differential pressure sensor to combat wash plant frothing issues to improve reading accuracy.
Owned by the BHP Mitsubishi Alliance (BMA), the Saraji coal mine in Queensland’s Bowen Basin produced more than 4.7 million tonnes of saleable metallurgical coal in 2021.
To help maximise the coal’s value, BMA also owns and operates a coal handling and preparation plant (CHPP). But an issue with foaming, irregular material density and inaccurate level readings had CHPP maintenance electrical supervisor Chris Whearty searching for solutions.
“We had an issue going on with the disc filter levels since about 2016,” Whearty told Australian Mining.
“Before I arrived (in 2016), there was an instrumentation specialist that tried a few different options. He went with an ultrasonic level transmitter which was trialled for about 12 months and due to that frothing we were still getting inaccurate readings.”
Whearty and the team then attempted a hydrostatic pressure transmitter for another 12 months. Still not having success, he then turned to long-time business partner, VEGA area manager Steve Foley.
Foley attended the Saraji wash plant and recommended the VEGABAR 86, an automatic electronic differential pressure (EDP) sensor that could operate consistently despite the foam and inconsistent material density through its density compensated level application.
The submersible VEGABAR 86 is suitable for level measurement in wells, basins and open vessels such as Saraji’s wash plant. The sensor’s front-flush abrasion-resistant ceramic diaphragm allows it to operate in harsh conditions like coal mining, where there are chemically aggressive liquids alongside dust and grime build up.
Identifying such a solution was made easier due to Foley and VEGA’s commitment to work with the BHP team in-person and on-site.
“The biggest thing that we’ve got to be aware of as a supplier is fully understanding their requirements and their process,” Foley said.
“You can see a photo, you can get be told all the stories in an email, but unless you’re actually willing to get on site, look at the process and understand what they’re going through, only then can you make a decision on what technology is best suited.”
Indeed, the VEGABAR 86 was best suited for the job. The EDP removes the need for maintenance workers to visit the sensor up to three times per shift, while ensuring reading levels are accurate and reliable.
Not only does the automatic nature of the VEGABAR save BHP time and therefore money, it also improves safety for these maintenance workers.
“Access is a major consideration in mining and minerals processing because companies like BMA are very safety conscious,” Foley said. “So it’s got to be safe to use and the advantage of this product is you don’t have to access it and touch it very often.”
Safety is also improved by a lack of debris around the sump in question, according to Whearty.
“It’s especially handy for the operators that had to plan to check each sensor, whereas now it’s automatic and you get a true reading. This means there’s no chance of overflowing any sumps,” he said.
“This improves safety because having no danger of overflowing means you’ve got fewer slips, trips and falls.”
With a simple design and a range of applications, the VEGABAR 86 sensor is a common go-to for Australian mine sites.
“It’s been quite successful,” Foley said. “We’ve got quite a few different applications involving the EDP in different mines. It’s installed at (BHP’s) Peaks Down mine in another coal application, as well as some other quite successful installations in Western Australia.
“And globally it’s been successful in gold mines and flotation cells.
“So it’s a good unique measurement that eliminates a lot of the troubles that are normally found when you’re dealing with froth and foam, varying densities and working with different minerals.”
This feature appeared in the May issue of Australian Mining.