Grinding & Classification Circuits

Grinding & Classification Circuits2018-06-17T09:51:34-04:00
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Started by Oberfuhrer
What formulation should I use for the estimated calculation of rubber type mill liners wear rate?
Last replied to by David
what do you mean by models? for manufacturer contact glarose@bradken.com + he can guide you on design/shapes. for general steel ball mill designs and profiles see https://www.911metallurgist.com/blog...
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1355
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Started by
Has anyone had any experience with the Outotec MillSense real-time mill charge analyzer? It is a very innovative approach but does it work? Are you using it for day to day decision making?
Last commented on by David
Welcome to 911M Peter
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1688
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Started by Victor Bergman
SAG Mill Process Control - What do you prefer? Controlling Weight (within a range) by manipulating mill speed and keeping a constant feed rate? Controlling weight by manipulating feed rate?
Last commented on by Lymon chibona
There are maybe other factors that can be used to control the Sag but the feed size has a significant effect on its throughput the aim is running at a high throughput at a low power draw larger feed s...
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Started by Helena Russell
Does anyone have a chart to know if there is any relation between the feed size and the size of the ball needed to grind the ore in SAG and Ball mills?
Last replied to by Unterstarm
Good to watch for potential build-up of oversize particles when initially running your circuit. There's nothing quite like starting to throw lots of oversize material into flotation.Good to know the v...
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Started by Sudhirkumar
What’s the effect of running the SAG Mill at a speed less the 75% of the critical?
Last replied to by Rahil Khan
If you have to reduce the SAG mill speed because of avoiding liner breakage, maybe it’s better to modify the shell lifter design. Low speed may cause decreasing capacity, higher steel ball and liner...
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2092
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Started by Sandeep Bisht
What are the reasons and solution for liner breakage? Tell us about effect of changing liner geometry, adding some feature to liners, type of material and metallurgical operation of liners on deceasing break.It may happen for both of them but since n...
Last replied to by Victor Bergman
Yes, correct. We have 2 different HPGR's, one for cement applications and the other one for minerals. The main differences are the wear protection (minerals: tungsten carbide studs) and hydraulic pres...
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893
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Started by
What are the chances to get peening in liners after a grind-out? Is it common to see the whole mill liners under these conditions when a grind-out occurs or is it correct to deduce these ball-hitting marks come from operational conditions?
Last replied to by
As with everything, we continually learn how to improve such procedures such as these - listed below are our current and well considered steps with explanations of why each step is made.[In priori...
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Started by Raje Singh
Anyone has experience in relating the Bond Abrasion index to liner consumption
Last replied to by Obergruppenfuhrer
See the paper by Carlos & Levi is very handy. "Measuring, Predicting and Managing Grinding Media Wear" by A.Giblett and J.Seidel 2011 also contains some very good data.http://is.gd/KK4H6E
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661
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Started by Sachin Prakash
Who knows what is the best machine or grinding mill for size reduction when the feed size is 3 -8mm and we want product size be( 200 -900)micron and -200 micron be minimum% because 0-200 micron is reject sizethe material is calcium carbonate
Last replied to by
Recently we have made some tests to produce a granulated material which contains no more too fine sandy, to thereby employ a hammer mill feed 15-18 t/h, F50= 3.5 mm and D50 = 0.6 mm. The Raymond mill ...
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796
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Started by Sudhirkumar
Is the grate discharge arrangement ideal for the secondary (ball) mill?
Last replied to by Rahil Khan
In simple words, grate discharge mills give higher tonnage, but produce coarser grinding, that may cause problem in your Flotation recovery, Grate discharge will also reduce your EGL. The best option ...
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1518
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Started by Gruppen
We are looking at a 1 MTPA comminution circuit that goes from a tertiary crush to a single ball mill (closed on a cyclone cluster) to produce a 100 µm P80 product. We're doing a trade-off study. Closing the tertiary on the screen or leaving it open!...
Last replied to by Gruppen
By the way this project has been stalled due to tenure issues but the challenge (minimum cost of getting into production, even symbolically) is still worthy of consideration. The design can allow for ...
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846
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Started by Subhash-Kumar-Roy
Does the phenomenon of mill liner packing also happen in dry SAG mills? In both Shell and head lifters?
Last replied to by Subhash-Kumar-Roy
In dry SAG mills the head lifters play important role. The ground materials should be distributed on suction area. Part of this job should be done by head lifters.
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Started by Marshal Meru
I’m a designer working in a foundry casting mill liners where we have some designs for ball and SAG mils but we have design of other companies like Norcast, Outotec, FLSimdth all OEM's. We want to create our own design for liner for mill ball and ...
Last replied to by
You might find these links interesting. These papers will take you through the basics.http://is.gd/aw84TWhttp://is.gd/qg8QFDhttp://is.gd/adw52TI worked for many years in Minera Escondida (BHPBilliton)...
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Started by
Has anyone had success with installing load cells for load indication on existing SAG Mills?
Last replied to by
Load Cells in my experience give a better and more rapid indication than bearing back-pressure 'interpolated' systems. I have tried to install them on all new milling installations; however, explainin...
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Started by Raje Singh
Differences between drives power draw of two drives sag mills. In a double drive/pinion SAG, we face different power draw between each drives. Can this be caused by charge motion or some others process problem?
Last replied to by Maya Rothman
I also think that as the costs for VSD systems decrease, plus that the technology is mature and becoming widely used on large machines, that this is why we are seeing more of them. However, even thoug...
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1059
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Started by
Having used weight control and power draw to control Mill operations, using Mill Sound to run a mill was a new one for me. I found it unusual and not that effective. Has anyone else used that style of operation control to run their mill and did you ...
Last replied to by Obersturmbann
In my experience mill sound is important but is only one parameter that should be used for mill control. It is complimentary to the other common control actuators such as speed, feed rate, mill mass a...
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2727
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Started by Paul Morrow
With regards to comparing grinding mills; what are the advantages of vertical milling machine compared to conventional ball mill? A more appropriate term is vertical roller mill or VRM for short.There are two different types of vertical mills: Verti...
Last replied to by Sachin Prakash
Just add small comments to the previous, you will not need classification equipment such as vibrating screen or hydrocyclone for Isa Mill or Verti-Mill circuit. A signature plot test work to determine...
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1349
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Started by Victor Bergman
Whether it is practical and/or worthwhile to run a Bond Ball Mill Work Index test at 500 mesh (25 micron)? Are there calculation alternatives? This would be for sizing of fine grinding or regrind mills.
Last replied to by Obersturmbann
We use grind curves over a range of work inputs using stirred media mills to determine the kWh/t to achieve the desired final particle size distribution. This can be done down to the sub-micron sizes ...
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1176
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Started by Rahil Khan
What is your idea about space between SAG mill shell liners? How much space would be appropriate?
Last replied to by
From an installers point of view! Most steel liner suppliers supply rubber widgets or void filling segments to prevent liner movement or creeping to a degree with the initial installation and prevent ...
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4475
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Started by
What is the effect of low ball % full on grinding efficiency?One of our clients is thinking of the future and has bought a ball mill that will be the right size someday, but is very large now.I know what happens to mill power from adjustments to % cr...
Last replied to by
Give me actual data of you grinding flowsheet: feed size, product size, power of mill motor, capacity, ball size, numbers & diameter of hydrocyclone ball charge, mill speed. I'm calculate optimum capa...
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622
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Started by Helena Russell
How to estimate the necessary flow rate of air to feed a row of six flotation cells agitators?
Last replied to by Obersturmbann
Take a look at this article for an approach:Miguel Maldonado, Rodrigo Araya and James FinchAn Overview of Optimizing Strategies for Flotation BanksMinerals 2012, 2, 258-271; doi:10.3390/min2040258http...
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709
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Started by
We are facing a problem at vertical raw mill that mill not getting feed according to designed capacity all things ok. Please share your thinking according to your experience. And one more thing if, in a vertical raw mill operating manual, it is descr...
Last replied to by Kumar Choudhry
Did you change new liner for table and grinding rollers? Could not get the meaning of all things ok, whether it was running with a designed capacity before?
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508
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Started by Zander Barcalow
A laboratory grindability test made in closed circuit! Should it be regarded as a miniature of a commercial mill operation? Should its performance be scaled-up to the size of a commercial mill?Does the screen analysis of its product and circulating l...
Last replied to by Obersturmbann
In general, the closed-loop tests are laborious and time consuming. The grinding environment within the ball mill is a first complicating factor for the scale-up. The type of classification used, have...
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2317
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Started by
What may be the probable reason of high temperature in slide shoe bearings of cement mill?
Last replied to by
First thing to do is to check the position of the temperature sensor installed on the slide shoe. Second analyze the high/low pressure oil system. Look for manuals and see working range parameters for...
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615
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Started by Hauptsturm
I am looking for some information about pressure drop in dry SAG mills? How designers calculate the requirement air flow rate for this kind of mills?
Last replied to by Subhash-Kumar-Roy
Pressure drop is the most important parameter in dry SAG mills because it can make material discharge possible. I depend on mill length and the amount of material in front of the max trunnion opening....
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528
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Started by
Is it true that the lifter release angle of recent installed SAG mills are more than 15 degrees? Will it be the future of lifter geometry and design?
Last replied to by Hauptsturm
Here at MEPSA, we manufacture cast steel liners for OEM's. The latest profiles designs we are working for them, consider SAG's lifters release angles with angles between 20 and 30 degrees
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593
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Started by
Do you know if it’s possible to supply a mill with Squirrel Cage Induction Motor Drive using low tension motors (480V) instead MT? (4160V) when power requirement is less than 1000kw?
Last replied to by Gruppen
Below 1000 kW it is not a big problem to operate the mill with a low voltage motor. The problem is the start-up, where you have 6-7x nominal ampere which is typically not possible for the start-up tim...
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Started by
Is there a general rule or a formula to calculate the ideal %ball charge in a SAG mill?
Last replied to by
One important issue: "Work Index is not Hardness", but is the energy we need to reduce from F80 to P80. Also I was reading about the ball recharge policy...for this is very important to know the Abras...
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955
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Started by Amar
What's your suggestion for best recommendation for aP80 of cyclone overflow for lead & zinc to feed a flotation circuit?
Last replied to by Kumar Choudhry
It is obvious thing that the mineral beneficiation process is to enrich the interested mineral quantity in the concentrate. It directly derives from the optimum liberation of the minerals from the hos...
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Started by Subhash-Kumar-Roy
In a grinding circuit, is there any relationship between SAG mill % solids and P80 (SAG mill product)? And what is the optimum % solid for sag mill?
Last replied to by Sandeep Bisht
Relation between Sag mill solid and product P80!Both are dependent on feed size. Dependent on Volume % solids in SAG mill. Dependent on ball charge volume. Hardness of ore. Recirculation load. De...
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Started by Unterstarm
Do the chemicals of grinding balls have any effect on the final processed product? What's the key chemical element of grinding balls affects the processed final products?
Last replied to by Sandeep Bisht
•High chrome ball wear is less by 50% than hyper steel balls.•Contribution of wear in flotation is negligible. It is the shape of ball till disintegration to zero is the contributing factor. The m...
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Started by Obergruppenfuhrer
As a comparison between Ball mill and Gyratory mill for potash plant, which one is better? (With the aim of reducing fine particles)
Last replied to by Sudhirkumar
Ball mills: They are used for coarser grinding. Mostly wet grinding. Wet process means multiple handling and more cost. Very rarely used for dry grinding. Cement, pellet feed. etc.Gyratory: It is used...
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843
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Started by Rahil Khan
Does anyone know about determining the breakage function of SAG Mill using JKMRC method and determining the b(i,j) for all sizes.
Last replied to by Maya Rothman
If you want to determine your breakage and selection function for any current operation you can use our Moly-Cop Tools SAG Model, we have an Excel routine to get your parameters, then you can use this...
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728
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Started by
Apart from Bond's EF factors (CA Rowland), what other scale-up factors are applied to lab BWI for large-scale ball mill sizing?
Last replied to by Maya Rothman
The EF factors are usually sufficient to size a large ball mill. There used to be a discussion in the industry about whether they were suitable above, if I remember correctly, 18 ft diameter. That dis...
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Started by
Through continuous improvement and the use of advanced technologies like SmartEar™, Pueblo Viejo are improving the control and operation of their SAG mill, resulting in reduced liner wear, more efficiency.Volume Title: 12th Mill Operators' Conferen...
Last replied to by Zander Barcalow
I can vouch for the usefulness of this system in a recent SAG milling operation. The Smart Ear system was used to optimise the operational charge filling setpoint, and to minimise time periods spent i...

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