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Improving minerals processing

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article image A tried and tested development by Nalco is set to improve solids capture by up to 40% while also cutting costs

New developments are improving solids capture by up to 40% on mines.
The goal of all mineral processors is to do more with less, and to make more from less.
This is especially the case as the mining boom slows and companies begin to cut costs where they can.
So a tried and tested development by Nalco, which is set to improve solids capture by up to 40 per cent while also cutting costs, is the first in a wave of innovation in this newly financially restricted arena.
According to the company, its recent development in trihydrate flocculant technology for alumina processing plants has now been released internationally following a number of site plant trials.
Dubbed 'HyClass', and first presented to the industry at the 9th International Alumina Quality Workshop in Perth last year, Nalco claims that "it represents the first major breakthrough in tri­hydrate flocculant technology since such programs were introduced into Bayer Process alumina processing.
"Based on laboratory testing and the results from these trials, this new technology is able to deliver underflow density increased of up to 20 per cent along with tangible cost savings and environmental benefits."
The concept of hydrate flocculants isn't new, having been used in the industry's alumina trihydrate classification circuits for around two decades.
Usually dosed into the secondary overflow launder or tray feed lines, they improve overflow clarity, increase settling rates, and improve general overflow composition and flow.
However while they have been successful in alumina processing, the rising cost of production as well as the constant need for improved productivity and efficiencies is driving the demand for better technology.
The fact is the mining industry is unable to spend money in the freewheeling way it has over the last two years, and has to now worker smarter - looking to minimise input and maximise its output. 
Nalco stated that HyClass is the result of this new demand.
Importantly for the industry, "the trials, carried out under operational conditions, actually mirrored the results first recorded in the laboratory test programs," it said.
"Reports from the site trials indicate a consistent improvement in fines capture, faster settling rates, and tangible improvements in underflow rheology - which will contribute to improved productivity, as well as cost savings."
During these trials the new polymer yielded the same overflow solids ratio as achieved with the formerly used product - "but with the dose rate reduced by up to 40 per cent," Nalco stated.
"Conversely maintaining the dose at the old rate would see a direct increase in production; at the other end of the equation overflow solids reductions in the range of 30 to 50 per cent were achieved, depending on the quality of the base product."
To understand the full impact of this over a year, for a standard refinery producing around one million tonnes of alumina per year, with a circulation flow of 1700 kilolitres per hour, the results are substantial.
Its captured overflow solids would provide a direct production increase of more than 3000 tonnes per year.
On top of this the improvements in yield due to the increase seed tonnage and surface area translates to an increase production of around 1500 tonnes a year.
At a net treatment cost of $60 000 per year, when the old treatment is replaced at an equivalent dose "this is a 500 per cent ROI".
Importantly however, as many mines look to reduce the wear on their equipment and get longer life out of their existing machinery and fleets, "this new technology has been shown to extend processing equipment life, including rakes and vessels". 

The company went on to say that "with the new technology capturing all the fines, scale build-up is virtually eliminated from processing equipment; this in turn will reduce maintenance costs and the number and length of downtimes.

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