Grinding & Classification Circuits

Grinding & Classification Circuits2018-06-17T09:51:34-04:00
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Started by banyechan
Our customers in CaCo3 grinding fileds,just sent us operating conditions in grinding.What types of balls are better for drying grinding?  
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507
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Started by m_aazami
Hello Everybody my question is: in whole the document about technical specification of ball charge media of ball mill, it is stated that the hardness of ball media in startup of the plant should be a little lower than ball media in continuous opera...
Last replied to by SmartDog
The slightly lower hardness is to allow the media to establish a natural size distribution faster.  When the mill is first stated a guess is made is to a media distribution and then it is operated to...
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164
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Started by Partha@Mech
E= 10 Wi (1/√P80- 1/√F80) E= Specific Energy, Wi= Work Index,P80= Output,F80= Feed After this we need to multiply certain factors such wet/dry Factor, Separation Factor, Dia. factor,  Open/Closed Circuit Factor etc.. E= 10 Wi (1/√P80- 1/√...
Last replied to by SmartDog
Note: "We assume Critical Speed as 70% of Nominal RPM" is backwards.  Critical speed is the rpm that cascading stops and the charge is pinned.  So it should read "We assume Nominal RPM as 70% of Cri...
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267
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Started by Saghar
Hello, I am working on air classification operations in a cement plant. The final air classifiers (High efficiency type, manufactured by polysius) have high values of bypass, let's say around 40%. I wanted to know what are common practices to reduce ...
Last commented on by Saghar
That was very useful. Thanks I will declare the results if I can change the feed rate of the classifier
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152
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Started by Saghar
Can anyone kindly help me determine selection function and breakage function in a laboratory rod mill? I need a reference that completely describes the process of determining grinding kinetics in rod mills
Last replied to by Saghar
Thanks for answering. I have determined the selection and breakage function in case of ball mills previously, using modified H&F method. Now I need to know that how different is the procedure for a r...
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1165
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Started by Babacata
Could someone please provide me a link or probably send a copy of Moly-Cop Tools 3.0 software? It's not listed on their site anymore. Thanks.
Last commented on by biggerthanpenny
Hi RommelAl Would it be possible to grab molycop tools off you as well? Many thanks
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300
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Started by Dachmann
Hello, I was told in this forum that economic efficiency is one of the major reasons for the ongoing popularity of Tumbling Mills in mineral processing. Concerning my questions I need some insight of experts with practical experience. Looking at SA...
Last replied to by David
A case by case trade off is to be done. Farnell Thomson Montreal based could do this. Here is a paper you will find useful.
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471
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Started by MSKabir
During rotation of a SAG mill, the three prominent zones are the grinding zone, tumbling or cascading zone and the cataracting zone (crushing zone). Are there any studies about the percentage of wear in the areas mentioned and what type of wear domin...
Last commented on by MSKabir
Thank you so much for the valuable feedback.
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451
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Started by MSKabir
After perusing through research articles I found out that the two most commonly used mill liners are pearlitic steel and white cast irons. However, I was wondering, what situations would involve using pearlitic steel as liner material or vice versa d...
Last commented on by MSKabir
Thank you so much for the feedback
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471
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Started by JuniorMet
How do you determine the charge level in a SAG mill and/or a ball mill (balls+pulp+rocks) and the interstitial space?
Last replied to by David
https://www.sagmilling.com/tools_millfilling
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548
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Started by JuniorMet
Hi colleagues. I want to know what is the percent solids we are working at, inside the sag mill. Should I sample the pulp discharged to the sump and measure % solids there? How can I calculate the solids percent using the circulating load or the over...
Last replied to by Todd H
It is always best if you can measure the solids directly but it is not always possible plus on a SAG there is often a trommel and a screen in the way.  You need to measure all the flows and the sump ...
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341
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Started by Sarah
Hello everyone,   I would like to know which one is efficient in iron ore crushing and grinding circuit: Jaw crusher+SAG mill+ ball mill 3 stage crushing + 2 stage grinding (ball mill)   Regards, Suvd
Last replied to by SmartDog
Without looking at the tonnages involved and the ore characteristics it cannot be determined. Both are efficient depending on your ore.  The actual efficiency of one over the other is dependent on th...
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361
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Started by Chisomi
what is dry classification
Last replied to by SmartDog
The following is a very simplified look at the topic. Mechanical classification is primarily done using vibrating screens or profile wire/sieve bends screens.  Centrifugal classification primarily d...
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434
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Started by Millza79
For a SAG Mill or ball mill; what is the difference between a installed motor power and Mill Motor Size at Pinion?   And why do SAG mills have a different Mill Motor Sizes at Pinion than ball mills (when they both have constant installed motor pow...
Last replied to by SmartDog
In addition to Alex's comments, there are additional "losses" in the mechanical side.  The input to the gears  and the output from the pinion to the shell are always different, with mechanical losse...
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664
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Started by richardh
Hi What is the optimum method of controlling a cluster of hydrocyclones used in a closed mill circuit so as to obtain the best performance?    Is simple sump level control sufficient?
Last replied to by Alex Doll
Ideal hydrocyclone control is constant pressure, feed density, and flow rate. These three things are difficult to control in the real world which is why people settle for poor hydrocyclone performance...
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582
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Started by Eder Figueiredo
Hi everybody, During performing some Ultrasonic Testing (UT) to measure the thickness of the mill discharge trunnion I found excessive wear. I can say it is in a critical state. Everything indicates that slurry seeped underneath trunnion or shell ...
Last commented on by Eder Figueiredo
Thanks, David. I will look for a Devcon representative in Brazil and also consider Hoffman engineering as a second option. For temporary repair with reinforced urethane filler. Does the structural ...
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536
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Started by Babacata
Dear All, I would appreciate your opinion, if you could give me some indication on our ball consumption at our factory, do you think that there is a room for significant improvement?   I am attaching the basic data sheet of our zinc-lead mine/fac...
Last replied to by David
if you want to reduce ball consumption, reduce your ore feed size. 35 mm is large https://www.911metallurgist.com/typical-average-grinding-ball-consumption/
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552
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Started by Tristopher1234
Our 12,500,lb cap. Ball mill is not level. This causes the charge to be 65% or so on one end and the other level is way below the balls on the other end.  I would think that this would not allow the material to grind properly on either end. The mil...
Last replied to by Alex Doll
What happens when you increase the water addition?  A higher pulp density might help to level out the charge. Is the mill actually level, or is it tipped towards one side? Are the lifters the same ...
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351
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Started by Rahul bhoraniya
hello everyone  please tell me how to measure capacity of batch type ball mill used in Ceramic body or Sanitaryware body? How to calculate guide me
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453
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Started by hojjat78
can we use polyurethane liners for ball mills? compared to rubber based liners, what are the advantages and disadvantages of polyurethane liners  
Last replied to by hojjat78
thanks
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414
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Started by Setta
Hello Guys  I'm experiencing some difficulties with pyrrotite ore grinding in the SAG mill. Ore has a bond work of about 15 kWh/t. We have a pebble crusher in close circuit with the SAG mill but throughput has been an issue due to ore hardness. Bal...
Last replied to by David
Setta, answering this would involve a 2-day training course. You have not given enough information to diagnose what is going on -- a ball mill work index is meaningless in this context.  throughput...
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510
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Started by Sandyhose
Hi There, We have a wet overflow rod mill which is being used to grind Malachite. We want to convert it into ball mill to get the finer product 80% passing 70 micron. Can we do the same? simply, can we convert rod mill to ball mill? if yes then wha...
Last replied to by SmartDog
Balls are usually added to the mill with the ore feed (after the initial charge).  This requires a bin over the feed belt and feeder to add the balls at the desired rate.  These are usually of the t...
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594
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Started by Hamid72
Hello everybody We have a ball mill in our plant with 2m diameter and 7 m length. I think that It is not a standard ball mill. Now I want to calculate the power draw of this ball mill and know how much must be the loaded ball in this ball mill. Can ...
Last commented on by mashudu
very helpful. thanks
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540
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Started by Hamid72
We are adding a new line of Iron concentration in our plant. And now I want to sizing a hydrocyclone so I need to know circulating load. How can I calculate the best circulating load for this circuit? Thank you for your help
Last commented on by Hamid72
Thankyou so much
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450
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Started by Hamid72
Hello every one. What is the best way to measuring the dry solid density of grinded iron ore? And what happen when the percent of solid in a ball mill is too high? For example 88% Thank you dear freinds
Last commented on by Hamid72
Thankyou
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744
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Started by amit_antu412
How can i control mill load with Trunnion bearing pressure ? We have faulty load cell in our SAG mill. We have previous relation trends when load cell was working fine. We need to develop relationship formula . Please assist me.
Last replied to by Jorge
Follow the link, https://www.911metallurgist.com/grinding/bearing-pressure-to-mill-load-control/ https://www.911metallurgist.com/ag-sag-grinding-circuit-automatic-control/  
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717
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Started by Hamid72
Hello every body. We have a ball mill that works with a 380 kw motor. How can I calculate that how much ball can I add to mill maximum? Thank you
Last replied to by David
go to https://www.911metallurgist.com/blog/ball-mill-motor-power-draw-sizing-and-design-formula enter your numbers in red until the kW Drawn by Mill at Pinion is what you need
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505
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Started by FarshidBsr
I need help with the size and selection of non-water cyclone(s) i can install to produce 45 t/h, 90% Bauxite - SG: 3.2 g/cm3  Feed-> Solid flowrate: 49.5 t/h (15.41 m3/h) - Slurry flowrate: 193 t/h (126.57 m3/h) - Percent solid : 25.65% w/w & ...
Last replied to by Jorge
In order to size cyclones, it is important to use the correct correction factors. It should be pointed out that correction factors are a relative measure of slurryviscosity and is affected by such th...
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449
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Started by ajm2019
We have a 4x16 ceramic lined ball mill and we are milling precipitated calcium carbonate. We are trying to to get to a gradation of D50: 3 micron and D90: 8 micron, however we are having trouble getting the gradation down. Currently we are at a D50 o...
Last commented on by ajm2019
Hi SmartDog, Thanks again! We've added the ionized air and that seems to be helping with our static. However, we are experiencing moisture issues. The feed into the ball mill is the lowest moisture co...
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408
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Started by Azadeh
Hi dear friends which one is the best choice in grinding circuit: 1- two large ball mills 2- four small ball mills this circuit is needed for grinding the Galena and sphalerite processing. clearly I should ask that which circuit is common in min...
Last commented on by Azadeh
Thank you for your comment my friend.
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406
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Started by reza1364
HelloIs there a standard for limit deformation roll forged balls at ball mills?for example limit size of roll forged balls?
Last replied to by reza1364
are you any body have all standards include (sampling, limit size, deformation, breakout) for roll forged ball mills?
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363
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Started by Mahdi
Hi my friends We production dry Iron Cocentrate with grade 65.5% without water. One of our problems is to grinding iron ore up to 75 microns.After charging balls in the mill, larger(50&40mm) balls at the end of the mill and smaller balls(25&30mm) mi...
Last replied to by FarshidBsr
Hey Mehdi,What is the type of mill liner? Classifying liners may help to obtain a good classification of the grinding balls if it is a single-compartment ball mill.Regards,
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504
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Started by Hamid72
Hello everyone How much is the range of Iron ore work index?  Thankyou
Last replied to by David
https://www.911metallurgist.com/blog/table-of-bond-work-index-by-minerals
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629
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Started by Hamid72
Hello everyone we have one dry ball mill and now we want use it as a wet ball mill. Can we do this? Is any difference between wet and dry ball mill structure?
Last commented on by Hamid72
Thankyou so much
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509
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Started by Teggry
Hi All, What are the options for reducing circulating load while running the mill? The tried and true method is to stop/reduce feed until the mill has time to grind out. I have heard also to increase dramatically the water to flush the mill out but...
Last replied to by David
Teggry, have you seen and read https://www.911metallurgist.com/grinding/grinding/ & https://www.911metallurgist.com/grinding/high-recirculating-loads-in-ball-mill-circuits/

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