Moatize Coal Mine’s Simple Solution to Blocked Fluidising Nozzles

Blocked fluidisation nozzles are a common problem in fluidised bed systems used widely in the mining industry, including at some of the biggest coal mines in the world.

The Vulcan Moatize coal mine in Mozambique continues, after almost a decade, to enjoy the benefits of a simple but highly effective filtration solution that has virtually eliminated blocked fluidisation nozzles – resulting in reduced maintenance, virtually zero downtime and increased output.

The Vulcan Moatize coal mine, located in the Tete Province of Mozambique, is one of the world’s biggest coal mines by reserves. Vulcan is the largest mining company in Mozambique, and also among the country’s largest employers.

Vulcan Moatize appointed DRA Global to design and manage the expansion project for the existing coal processing plant, which produces both metallurgical coal used in the manufacture of steel, and thermal coal for generating heat and power in thermoelectric plants.

Reflux™ Classifiers are used in coal beneficiation. Reflux™ Classifier is a combination of lamella settler, autogenous dense medium separator, and fluidised bed separator. The fluidised bed separator acts as the primary density-based separator. A constant supply of fluidisation water is essential. This water is introduced to the RC via fluidisation nozzles, and it is crucial that the water must be debris-free. Blocked nozzles – a common problem in fluidised bed systems – results in substantial loss of production time.

In addition, process water is re-used on mines. This water is collected from around the plant, and normally contains larger suspended solids that can damage equipment and instrumentation. This causes process interruptions and delays.

These challenges had already been encountered on the old coal processing plant at the Vulcan Moatize coal mine, where a motorised self-cleaning filter was previously utilised. It featured an inefficient cleaning mechanism with rotating parts that could not accommodate larger particles. These particles would get stuck in between the screen and the cleaning collector, and would eventually accumulate inside the filter, causing blockages and breakdowns. Operators were forced to continually open the filter manually to unblock it, resulting in lost production and high operational costs.

Fortunately, DRA Global engineers tasked with the expansion of the coal processing plant had previous experience with Kleerflo filters from Superior Filtration, a South African-based industrial filtration specialist that supplies filtration solutions in 32 countries, with a strong emphasis on mining applications.

Kleerflo Filters are pressurised, automatic, self-cleaning filters installed in process lines to remove suspended solids from water, and offer continuous flow and a strong, positive backwash action that ensures thorough cleaning of the stainless-steel screens that never need to be replaced. Kleerflo’s unique design has no rotating parts or close tolerance elements, very few moving parts and no electric motor, further ensures robust performance, proven reliability and low downtime and maintenance costs and no damage to downstream equipment.

Since the first Kleerflo filters were used at the plant almost a decade ago, the fluidised bed systems have worked continuously, with all the debris and suspended solids in the water supply eliminated.
The first Kleerflo filters were installed at Moatize in 2014, and the previous filters used in the old plant have since been replaced by Kleerflo filters – which were also incorporated into the plant expansion project from the design stage. Superior Filtration continues to stay in touch with the mine to monitor the performance of the Kleerflo filters, and to provide technical support and spares when needed.

The benefits of choosing the right filtration solution have been highlighted at other coal mines across the world, including on FL Schmidth beneficiation platforms in Australia and at the Exxaro Grootegeluk coal mine in Limpopo, South Africa. Here too, Kleerflo filters ensure the mines run without interruptions caused by failing water filtration, manual cleaning and continuous maintenance or damaged downstream equipment.

The Superior Filtration diagnostic team invites both design engineers and end users of filtration systems to make contact via telephone or WhatsApp and to benefit from its no obligation diagnostic service and technical input.

“Our team, with more than 38 years’ experience in water filtration in mining applications, is well-positioned to provide crucial advice and consultation to end-users, as well as engineers, consultants, contractors and project managers,” says Albert Bam of Superior Filtration. “We can assist in addressing current filtration system problems, and also help ensure that sub-optimal performance and failures can be prevented at design stage – ensuring filtration solutions that work for decades, and ultimately leaving a legacy of low risk, low downtime and lower costs.”