Wednesday, 7 November 2018

High capacity fine screens: the future for closing grinding circuits

Although Prof. Alban Lynch has been involved with hydrocyclones for very many years, in his conversation with me (posting of 11th August 2014)  he said that "the way they are used now is an absolute nonsense, with circulating loads in some cases of well above 200%. The future is high frequency screens.....it is very clear that these screens are so much better than hydrocyclones."
By classifying by size-only, screens, compared to hydrocyclones, give a sharper separation with multidensity feeds and reduce overgrinding of the dense minerals. Derrick Corporation is the leader in this field and at Comminution '18 Nic Barkhuysen, of Derrick Solutions International, South Africa, said that replacing the ubiquitous cyclone cluster with Stack Sizer screens creates additional capacity, improved mineral recovery and a simultaneous reduction in power consumption. He said that payback ranges from two to seven months, based on sixteen case studies where before and after audits were performed, replacing cyclones with Stack Sizers.
At Comminution '16 Elizma Ford, of Mintek, South Africa, evaluated the potential throughput benefit of adopting Derrick fine screening technology in a PGM slag ball mill circuit. Mintek was contracted to quantify the effect on circuit throughput associated with changing from the current hydrocyclones to Derrick fine screening technology, and Elizma concluded that it is becoming apparent that the ability of these machines to accurately classify by size only at efficiencies in the mid 90% range, as fine as 45 micron, has resulted in a paradigm shift in milling circuits, replacing hydrocyclones in the closing of secondary and tertiary circuits.
Derrick Corp polyurethane screens on display at SME '16 in Phoenix
We will hear much more of developments of such fine screening technology at Comminution '20, as we are pleased to announce that Derrick Corporation has confirmed sponsorship of the event, the first time that the company has sponsored an MEI Conference.
Current Comminution '20 sponsors
The latest updates on Comminution '20 are at #Comminution20.
Twitter @barrywills

1 comment:

  1. I also mentioned in many forums, as Dr.Lynch said,that do not blame cyclones while you are using them as size separating units in a grinding circuit. Yes, with the excellent developments by Derrick, I have been following the screen performances and I am sure grinding circuits would greatly benefit. Recently, while advising a major iron ore beneficiation plant,I strongly recommended these screens in place of cyclones. With more information and plant data coming in your forthcoming event, I am sure many existing/future plant people will take advantage of this major development in size separation unit operations.
    Efficiency of screens and complex nature(values getting liberated at coarse sizes etc) are to be born in mind.
    Rao,T.C.

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