Engineering & Mining Journal

DEC 2018

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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Page 55 of 115

FLOTATION 54 E&MJ • DECEMBER 2018 as part of the cleaning circuit in a con- centrator plant. It creates a high-pressure jet of mixed air and slurry, which shoots through a pipe, called the downcomer, that penetrates and empties into the flotation column. The downcomer is where particle and bubble contact first occurs. "The plung- ing jet of liquid shears and then entrains air, which has been naturally aspirated," Glencore Technology personnel reported in a white paper. "Due to high mixing ve- locity and a large interfacial area, there is rapid contact and collection of particles." In the tank, secondary bubble-particle contact occurs. "The velocity of the mix- er and large density differential between it and the remainder of pulp in the tank results in recirculating fluid patterns, keeping particles in suspension without the need for mechanical agitation," the company reported. The bubbles gather on the surface of the column, and the resulting froth is re- moved by froth drainage or froth washing. The key technology in the system is the downcomer, which features no moving parts and is based on simple physics to optimize efficiency and cost effectiveness, Lawson said. "You create a hydraulic field and the slurry is drawn up into the down- comer because there is a pressure differ- ence as that plunging jet goes through that orifice," she said. "It naturally draws air from the atmosphere, so you don't actual- ly have to use compressors, or any energy associated with compressing air." The original seed idea for the downcomer is attributed to a laureate professor, Graeme Jameson of the University of Newcastle. In search of a means to optimize flotation performance of a lead/zinc concentrator, he was commissioned by Mount Isa Mines, in Queensland, Australia, to develop the idea, which he patented in 1986 on behalf of Newcastle Innovation Ltd. That year, the resulting pilot cell was tested. Three years later, two full-scale cells were installed in the lead-zinc concentrator at the mine. Two more were built that year for a similar con- centrator at nearby Hilton mine. From there, the technology gained in popularity and demand, seeing relative widespread adoption in Australia first before going global. In the roughly three decades that followed, the cells were ad- opted and deployed to plants processing precious and base metal ores, coal, in - dustrial metal ores and oil sands. In 2013, Jameson was named New South Wales Scientist of the year. That year, Jameson Cells at Australian sites were credited with recovering some $30 billion in export coal. In 2015, the solution won the Prime Minister's Award for Innovation for its role in the Australian economy. Such accolades and figures point to the value the cells add to a circuit and plant, Lawson said. The solution is reput- edly excellent at fine particle recovery, is known for the small bubble size generat- ed without mechanical agitation, and is pitched as being easy to use and main- tain. Those qualities are of immense val- ue to any plant, she said. For example, for a copper miner, the downcomer ensures the entirety of the feed jibes with bubbles in the contact zone. "Other devices rely on probability," Lawson said. "We are now 100% certain that a particle has an opportunity to at- tach to a bubble." A copper miner, therefore, would enjoy a higher probability of bubble-particle attach- ment in a single stage, she said. "You've got the ability to soft wash, which will im- prove your concentrate grade, and because the Jameson Cell has such small bubbles, it has a much greater ability to recover tons of concentrate," Lawson said. "In the same footprint, you are able to recover signifi- cantly more tons of concentrate, making it a more efficient use of capital." For a molybdenum miner, the down- comer doesn't allow the target particles to behave the way they normally would in a conventional cell. "Moly flakes tend to be long and skinny and very flat," Law- son said. "Particles of that shape have a habit of just following streamlines in the water. The beauty of the Jameson Cell is it doesn't allow a Moly particle to behave according to its shape." For a gold miner, the downcomer en- sures rapid particle-bubble attachment, which prevents the deposition of calcium on the surface of the gold. "You need to recover it as quickly as possible by using a Jameson Cell at the head of the circuit," Lawson said. "Those gold particles are re- covered fresh out of grinding or regrinding before they have an opportunity to have the calcium deposit on their surface." Headlines reveal the technology is currently seeing sustained demand. In the last few years, even amid the bust and aftermath of the super cycle, a handful of majors and juniors adopted the solution as a part of brownfield projects. Telson Mining Corp. announced in the third quarter of 2018 it will test zinc flotation using Jameson Cell technology, hoping to increase zinc recoveries and zinc concentrate grade at the Campo Morado mine, in Guerrero, Mexico. In August 2017, Mount Isa Mines reported there were 350 Jameson Cells installed in 28 countries. Above, the solution at a base metal mine. (Photo: Glencore Technology)

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