Grinding & Classification Circuits

Grinding & Classification Circuits2018-06-17T09:51:34-04:00
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Started by
Why do ball mills have such high circulating loads?The ball mill grinds. The cyclones separate. But the pump neither grinds nor separates. So what is the purpose of having such a big pump to maintain high circulating loads in our grinding circuit?A ...
Last commented on by margaret.aniawu
This is one of the finest explanations I have read so far. Thanks Prof
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1690
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Started by Maya Rothman
What is the best way of measuring and quantifying the grinding efficiency of mineral slurries? I am referring to determining energy savings by improving efficiency. Would the Bond Work Index be the best way?
Last replied to by Unterstarm
Operating work indices include motor, drive and grinding mill efficiencies and inefficiencies, therefore, are not directly comparable to work indices obtained from grindability tests performed on the ...
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Started by Maya Rothman
Can anyone help me regarding the usage of a dry Grinding Aid & Dosing Pump for grinding of Ground Calcium Carbonate? I am planning to use grinding aid and require assistance for choosing correct aid, pump and dosage.
Last replied to by David
Hi Arif, am not if Maya is around but here is a report you may find useful https://www.911metallurgist.com/blog/grinding-aids
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Anyone has experience for TBS (teetered bed separators)?  I would like to know how much is the feed solid% and which size fraction is working better than spiral?
Last replied to by
Thanks to you all. i want to use this machine for coal for size range of 0.3 mm up to 3 mm. you mentioned good points.I found useful http://www.saimm.co.za/Journal/v102n07p385.pdf
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Started by Maya Rothman
Hydrocyclones sort particles by weight, hence if mineral of interest is dense it will tend to create slimes/fines (say -10 or -20 mm). Would screens prevent this? Any case study of screen technology the work well enough to provide a fine product of i...
Last replied to by
Separation efficiency of cyclones depend on how the cyclones are operated and controlled. This means first selecting correct gear for the specific application. Then decide on the operating / control p...
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Started by
What is the optimum/possible ash product size P80 that be obtained a comminution operation using rotary breaker in coal preparation ? What modifications can I make to improve ash reduction?
Last replied to by Victor Bergman
I would suggest you aim to increase the 'open area' of the breaker. This is the proportion or quantity of holes relative to the total surface area. This may impose structural constraints, but ultimate...
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Started by
For me it is interesting to see a lot of discussion around the topic of reducing costs for grinding, but very little comment or effort apparently being put into understanding the requirements of the grinding in the first stage. The question of why ar...
Last replied to by Victor Bergman
We have put a great deal of time into secondary grinding by gaining much better control of the forming of a small ball population. Having the media remain round (Spherical) during deployment life is n...
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Started by Helena Russell
Is it advisable to use a SAG mill for small, say 2000 TPD concentrator operations? The processing, in this case, is a complex zinc/tin mineral and we are afraid a SAG would P80 produces too much fines (since the tin is to soft brittles) (tin cassite...
Last replied to by Helena Russell
Thanks to veryone. I agreed that SAG is not the best option in our case. So still evaluate some alternatives. Also Gekko, on this application is not optimum.Thanks again for your help.
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Are the old Allis-Chalmers Abrasion Index and calculations for Steel Balls and liners consumption still valid?  The Allis-Chalmers Standard Abrasion test has been used for several decades to calculate steel consumption. Current advances in alloys ...
Last replied to by
I think you have made a point here: the grinding circuit needs to be under control before someone tries to assess steel balls consumption. "Under control" means that operators in each shift operate us...
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Started by Victor Bergman
For a conversion of mill lining from polymet to steel; What effects will there be on power draw, grinding or other operating/performance variables? I am looking at the possibility of converting a steel/rubber hybrid AKA Polymet lined SAG mill to ste...
Last replied to by David
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I'm faced with contradictory claims concerning classifying liner regarding their effectiveness, energy efficiency or applicability for high tonnage or hard/abrasive ores. Litterature is really scarce on this subject. Classifying liners are a kind of...
Last replied to by David
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Started by
I would like to know the relationship between mill weight and mill liner wear, is there an existing model for this? Has anyone looked at this before? Obviously low mill weight can impact toe position, reduce attrition and abrasion breakage, increase...
Last replied to by
Scanalyse (now Outotec) are investigating these type of relationships by integrating precise liner wear and volume measurements with mill operating parameters, including mill weight. One the Analytica...
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Started by Paul Morrow
During mill circuit design, many people prefer to have two pumps to one cyclopac (group of cyclones)- one operating and one standby, while many people prefer to install only one pump for one cyclopac (hydrocyclone-pac). Advantages for two pump opti...
Last replied to by Paul Morrow
Thanks everyone for your great contribution! Hope to see comment from more people especially problems you see in your operations, although I may not be able to respond from now on.
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Started by Maya Rothman
Can any one suggest me an updated book on comminution (specially grinding, tumbling mills), which discusses about control, simulation and optimization of crushing and grinding machines and circuits. I own Communition practices and advances in Commun...
Last replied to by Bob Mathias
A good textbook for mineral processing is the SME Mineral Processing Plant Design, Practice and Control volume, which has good introductory sections on grinding. It is geared towards undergraduate stu...
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Started by
The smaller cylpebs have all migrated towards the feed side of the mill, and the larger cylpebs are at the discharge end. What do you think causes that? Does anyone have advice other than dropping the charge, to bring the media back to large on feed ...
Last replied to by
We have magnets on both the discharge and the feed end of the mills. Yes, we have seen high wear on the classifiers, not necessarily the blades on the rotor, but the top and bottom plates wear quickly...
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Started by
Can we avoid the death of SAG mill and Ball mill? Will they someday be replaces HPGR and VERTIMILL in order to save energy and simplify flowsheets. Retrofit with HPGR and abbandoned the SAG/AG mills?
Last replied to by
Sometimes we need to follow laws even if are in loss or difficult to follow. Or else our business will get closed soon. Today's environmental laws are --Convert all broun technologies to green technol...
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Started by Bob Mathias
There is a strong push in the research community on optimistic energy efficiency through measuring minimum energy is required for comminution and benchmarking energy efficiency of different sites. On the other hand there are people who think optimizi...
Last replied to by Paul Morrow
In conventional base metal milling throughput always trumps recovery for maximizing revenue. This has been demonstrated over and over again. TPD also trumps energy efficiency, especially when the pla...
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Started by Bob Mathias
A complex analysis at a pilot plant scale is very hard to duplicate in actual production. I'm not sure you can avoid the trial and error method. The bottom line is the kilowatt hours per ton required to achieve maximum recovery. Several SAG mills ha...
Last replied to by
Very interesting topic here. I missed your presentation at IMPC so I will take a closer look to the paper. It is strange to see opposite direction (increase or decrease ball size) to increase SAG thro...
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Started by Maya Rothman
Hi, Am I working on a Antimonite/Stibnite Ore Project (scoping) and I need Bond Work Index values. I do not have a lab not equipment at hand. What is a good estimate? Thanks
Last replied to by Maya Rothman
Thank you very much, I saw in Mintek mineral handbook it was 15.9 but confirmation was needed.
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Started by Paul Morrow
A LIBS On-Stream-Analyzer VS XRF- X-Ray OSA On-Stream-Analyzer are similar in that they are used for elemental analysis, but LIBS can measure the light elements where XRF struggles. LIBS are generally much faster in all cases, an analysis can ...
Last replied to by Paul Morrow
Compare Lebedinsky GOK and Stoilensky not entirely correct. Because 70% of the concentrate obtained LGOK 7-8 stages of magnetic separation (mineral processing plant + secondary benefication plant) and...

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