Modern Mining September 2019

PRODUCT News

Weba chutes to optimise silo ore flow at SA gold mine

Specially designed ore silo chutes from Weba Chute Systems will be installed at a South African gold mine to reduce mill wear and other processing challenges caused by the uncontrolled flow of mined material into the mills. Developed in collaboration with Kwatani, a leading local manufacture of vibrating screens and feeders, Weba Chute System’s solution must also deal with frequent large- size material as the mine has no crushing stage before the milling circuit. According to Weba Chute Systems technical advisor Alec Bond, the over- feeding of material through the existing manually-operated chutes is causing regu- lar ‘mill vomit’ in the mine’s four mills. The inconsistent feed exacerbates wear on mill bearings as the material’s weight shifts

forwards and backwards inside the mill. The waves of material causing the ‘vomit’ carry insufficiently milled material out of the mill, including large chunks of rock. This leads to problems for the downstream mineral processing facilities, including inef- ficient recovery in flotation cells and even blockages in pumps, says Bond. “The challenge starts with the existing chutes needing constant supervision and control by operators, being opened and closed with a chain block device,” he says. “Our solution was to design a robust, self- controlling chute and feeder system that would ensure an even flow of material into the mills.” He adds that the mine’s existing system has no means of closing the silo outlet; any maintenance at the chute area requires the

mounting structures have been designed to accommodate each chute and feeder. There will also be civils works below the silo to provide a solid foundation that absorbs vibrations from the feeder. A serious challenge is over-sized rocks in the ore feed, which can be up to 800 mm in size. This makes it important for chute designs to accommodate the worst-case scenario of chutes choking, says Hunkin. He notes that the flow of material is also controlled to prevent direct impact onto the conveyor belt feeding the mills, and to ensure central loading onto the centre of the belt. “If the material from the feeder is biased to the one side, our chute brings everything to the centre of the conveyor,” he says. “This enhances the consistency of material flow into the mill.” Bond emphasises that the customer motivated for a concept change to address the challenges being experienced with the silo feed. “Given our materials handling experi- ence, design expertise and high-quality local manufacturing facility, we were able to work closely with the customer and with Kwatani to turn this new concept into real- ity,” he says. “Our solution promises direct savings in terms of mill bearings, as well as less mill downtime. There will also be significant gains in terms of recovery rates in the plant if the flow and size of milled material can be improved.” mining industry in particular are able to pre- vent dirty fuel from ever reaching valuable equipment or bulk storage tanks,” he says. The FK36000 consists of a hand- operated pump, four fuel cups, a litre fuel container, replacement NanoNet® media patches, and a test result interpretation card. NanoNet® is an advanced filtration media that traps and retains contaminants, even under real-time vibration and flow surge. The technology leads to greater protec- tion of fuel injection equipment, resulting in extended service intervals of up to 2 000 hours, improved engine efficiency and fuel economy, and reduced downtime and main- tenance costs. Cummins Filtration, website: www.cumminsfiltration.com/africa Weba Chute Systems & Solutions, website: www.webachutes.com

emptying of the silo and the stoppage of the mill. Each of the four silos has three outlet chutes. “We therefore added a spile bar arrangement which seals off the silo,” says Weba Chute Systems designer Wesley Hunkin. “The Weba chute, which is choke fed, is placed under this installation. This allows the feed rate to be con- trolled by the Kwatani feeder, which has been integrated into the chute design.” The vibrating action of the feeder controls the tonnage and feed rate to the mill, keep- ing the flow constant. New

One of the specially designed ore silo chutes from Weba Chute Systems for installation at a South African gold mine.

Portable fuel cleanliness analysis kit from Cummins The Fleetguard® FK36000 is a reliable solu- tion for testing fuel cleanliness in the field, according to Cummins Filtration Mining Sales Manager Tinus Naude. Testing can identify dirty fuel and, more importantly, the source of the contamination through sup- ply, delivery, storage, handling, and other practices.

to the ASTM D2068 FBT number. “Clean uncontaminated fuel is key to optimal fuel system performance and lon- gevity for engines in the mining industry. Without high-quality fuel filtration and regularly-scheduled servicing, fuel contami- nation can lead to costly repairs and engine downtime,” Naude comments. “The better the fuel quality, the better the engine perfor- mance through the fuel system. Component life will also be extended.” Naude notes that a global fuel cleanli- ness study has revealed that more than 50 % of fuel used does not meet the sug- gested industry cleanliness levels. “By testing the fuel source on-site, clients in the

The FK36000, a portable fuel clean- liness analysis kit, allows for on-site testing of fuel cleanliness, with immedi- ate results. In addition, no power source or batteries are required to perform the test. Most tests use only a litre of fuel, and require five to ten minutes. Results are interpreted immediately, and also relate

50  MODERN MINING  September 2019