The first half of 2013 has brough a number of anticipated milestone for Fortescue Metal Group's Solomon Mine Project, as the finishing touches will be applied to the Luhr Filter cleaning and ventilation systems at the Firetail and Kings mines.
With a value over $8 million, the dust control and ventilation systems for these two ore processing facilities (OPF) make use of reverse air cleaning technology aimed at reducing emissions and energy usage.
Luhr's proposal included negotiating the purchase of four pre-owned low-use dust collectors from another customer; these were refurbished and all moving parts were replaced. Refurbishment included new reverse air cleaning systems, screw conveyors, rotary valves, access stair towers, access platforms and support structures. After the restoration, all four practically new packages were covered by a 20-year performance guarantee.
Fortescue's requirement for speed was a leading factor in their decision to go with the timesaving refurbishment proposal.
Anne Jepson, procurement lead at Fortescue noted that "we were under some very tight time pressures and Luhr Filter met our requirements through their resourcefulness".
Four horizontal bag reverse air filters and three horizontal reverse pulse filters were implemented across the two Solomon sites, requiring air flows of up to 146,500m3/hr.
Two stockpile ventilation systems were installed in underground tunnels for diesel particulate and heat, ensuring they are compliant with updated Diesel Emissions legislation.
A relatively new concept to the iron ore market, Luhr's reverse air off-line cleaning design utilises an indexing medium pressure reverse air fan and pulse system to eliminate the need for compressed air.
The cleaning air is drawn from the surrounding ambient air, avoiding contaminating the clean side of the bags in the event of a leaking bag.
Trevor Baud, general manager of Luhr Filter explained the system is termed 'off-line' cleaning since the plenum attached to the travelling carriage isolates the bag row being cleaned as well as the rows on either side of the row being cleaned.
This avoids dust re-entrainment on the adjacent bag rows and lowers the pressure required for effective cleaning because the row being cleaned is isolated from the main induced draft fan suction.
After the cleaning cycle, the filter bags gently 'deflate' back onto the support cage and the carriage indexes to the next row.
This gentle action reduces the dust emissions and extends bag life compared to a compressed air pulse cleaning system.
All seven fabric filters supplied for the Solomon Project were provided with Luhr Filter's horizontal flat bag design, which not only reduces the overall size of the packages but also minimises the manual handling hazards encountered when maintaining the equipment.
By avoiding awkward heavy lifting on required on a vertical bag filter, where hundreds of bags at foot level must be lifted out for cleaning, personnel are protected from unnecessary strain.
The Luhr Filter horizontal bag arrangement allows the access doors to be hinged vertically, avoiding any lifting when opening.
Depending on the height of the selected filter bags, most are accessible from a standing position as opposed to a bending position.
Luhr filter also limits the length of their horizontal bags to 2.5 metres; the practical advantage of this is realised when replacing the bags, as the bags are of a manageable size and weight.
The reverse air cleaned systems also remove the need for long, awkward pulse-jet tubes which need to be removed before changing bags, thus avoiding another manual handling risk.