Grinding & Classification Circuits

Grinding & Classification Circuits

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Started by CHILOBA
Hi I am new in mineral processing industry and I need to know when and how you charge grinding media when ball mill is in operation
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Last commented on by niloufar
is there any automatic system to add balls without cutting the throughput?
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Started by epiphane
good evening friends, I need your help, I'm looking for a way to increase the life of the SAG liners. someone can help me find a solution to that. what study can I lead?
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Last replied to by Shivam_Nigam
Hello Epiphane, were you able to get the info requested above for the guys.It will be important to know the Size of the Mill and especially the Liner Type with its present Wear Life. There are options...
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Started by Peter.Li
Herbst et al. proposed a procedure for ball mill scale-up. It is based on linear relationship between selection function S (1/min) and specific power P/H S= SE×(P/H)  Question 1: "H is the mass of the charge in the mill excluding the media" Doe...
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Last replied to by emilyfreire
Peter, to determinate the power in the ball mill or in the rod mill, we can use the Rowland's equation.  The equation is attached. Regards.  
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Started by jono1028
I have a problem that I'm seeking input.   I have a pressure roller in a paper document reader which runs roughly at 2,000 RPM at bursts of 1000 revolutions per cycle and always a 10 second or more pause between cycles.   My current roller mat...
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Started by Rahul bhoraniya
Is any one have fundamentals of ceramic ball mill? is there any method or material so i can decrease grinding time of CERAMIC BALL MILL? please help me.
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Last commented on by Rahul bhoraniya
Its wet type. And material is slurry used for glazed body. Hello please help me to optimise size of grinding mill - Reducing ceramic ball mill design mass of MS
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Started by oguzgunes
Hi all, I am wondering about the time of grinding in ball mills. How can I calculate the retention time? Which parameters should be considered? Thanks in advance..
Last commented on by SmartDog
You did not mention the rate you are adding more media. This also should be accounted for. see: https://www.911metallurgist.com/grinding/charging-grinding-media/
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Started by SAKAR
which rubber is excellent for ball mill rubber liners? what should be physical properties and qualities of ball mill rubber liners?
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Last replied to by Sandip Trivedi
Nice information to make a best formulation. But SBR and PBR have a poor tear properties compare to NR, PBR has own reliance and abrasion properties good, mill where high tear and cut resistant requir...
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Started by Jaime Jacob
Hello I am begining to study the modelling of the comminutions systems and I would like to have some examples of determinations of the breakage and selection matrix. Anyone have some documents that explain this?   Thank you very much..!!
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Last replied to by MillMan
As Alex said, if you love hardship, see this PDF. Its conclusions are that an in depth review of the PBM used to simulate industrial wet grinding has found major flaws in the model showing- There ...
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Started by srinu1234
Dear all,  Have a good day! I am trying to determine ball mill work index for a very soft . If I follow bonds procedure to do experiment, not able to determine. The following is the data of ore sample. F80% = 2300mic Mesh of grind =300mic -300mi...
Last replied to by Alex Doll
The objective of the Bond work index tumbling tests is to arrive at a steady-state where the amount of ground material is constant between the stages.  One way to short-circuit the early instability ...
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Started by Sayed9
Hi we have replaced the girth gear of a ball mill used for coke grinding, and we have completed gear alignment. our procedure to use four holes of the gear fixing bolt , drill these hole to increase the diameter and then for reaming out . The purpo...
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Last commented on by Sayed9
Hi , We are using magantic drilling machine with HSS drilling bit . Have you used Rotabroch for drilling a girth gear ? Annular Cutter will do the job with a good accuracy ?
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Started by Hermann
Hi All, we want to mill a relatively soft galena in limestone ore to prepare it for gravity concentration. Flotation is not possible at the site. The ore is easily liberated, so a grind down to about p80 of 1mm is ok, to feed it to spirals and shak...
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Last replied to by Deano
To produce a milled product at around 1mm top size the most efficient way to get the material milled with minimal fines is by using a three stage jaw crushing circuit with 1mm interstage screening bet...
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Started by Charlie
Could you recommend a suitable calculation for ball mill charge volume using the chord length of the ball charge? We are currently using the calculation for distance between charge to top of mill. We would like to use the chord length method as well,...
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Last replied to by Todd H
https://www.911metallurgist.com/blog/ball-mill-charge-volume-calculation https://www.sagmilling.com/tools_millfilling Might be something here to help your calculations Todd
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Started by samuel82
Whats your opinion for TPL (turbo pulp lifter) for SAG mill? It seems that by adding a TPL could help increase energy efficiency and reach the SAG mill maximum capacity.    
Last replied to by David
Samuel, here is an excerpt of a paper by https://www.linkedin.com/in/david-royston-02765013/ Modern Semi-Autogenous (SAG) Grinding Mills can be up to 12 metres in diameter (absorbing up to 20 MW of ...
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Started by FarshidBsr
Hello Dear Friends, We are working in a plant with single stage grinding using three parallel wet three compartment ball mill. Each ball mill operates in a close circuit with Classifier. The fineness of ball mill product is OK so the circulating loa...
Last commented on by FarshidBsr
There are 3 ball mills in our plant so we should differentiate between ball mill power and total power of ball mills which is sum of each ball mills power. By increasing throughput the mill power will...
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Started by Guelb22
Hi All, The shell liner of the SAG mill wear in different rate depend on the position of the liner ring. Do we replace the half shell liner due to only wearing discharge end ring ? how we can manage that to replace the worn ones in time without repl...
Last replied to by David
What you are trying to do is not something I have ever done or seen. We change either the complete shell or half (in a High/Low setup).  We do not change half the DE or FE. You need to review your ...
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Started by hulk
hi,how are you What are the reasons and solution for Sag mill bolt breakage? Tell us about effect of changing liner geometry type of material and metallurgical operation conditions on bolt  breakage. thanks
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Last replied to by sslupsky
As mentioned earlier, there could be a number of reasons.  We helped investigate bolt breakage of a rod mill by monitoring bolt tension.  The key finding from that work was minimizing liner movement...
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Started by mokhtaraazami
Hi everybody I work in a iron ore beneficiation plant in Iran. in this plant the feed size is less than 10 mm which first enter to the HPGR (in open circuit) and its product size is less than 6 mm which goes to the open circuit ball mill. my questi...
Last replied to by raghdmuhi
https://youtu.be/Fr9XHChvKIY
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Started by Devon2017
Hello, I am a Placer gold miner in Desperate need of professional answers about an old, large abandoned Gold Ball Mill I found, and contents that were left behind. The answers I need are mainly how the recovery methods are completed once run ...
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Last replied to by Devon2017
And the town high school here takes all my used nitric acid and recycles it for free for me as they have to recycle they’re own every so often and since it’s paid for by the school board and I’m...
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Started by Simba marshy
how can I reduce the the tonnes of rejected by a grate discharge ball mill    
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Last replied to by Todd H
Further to above - did the amount of rejects suddenly increase? Ore type change; Feed rate change; Pulp density changes; Feed size change? Has the grind size changed? Is this a new mill with an ungr...
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Started by sajjadaghazadeh
Hello Dear Friends, I hope all of you are doing great. I do have a question related to ball mill liner types.  We are using a ball mill with diameter 3m and length 4.5 m in our plant. The ore is Magnetite with low amount of hematite. Gangue minera...
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Last commented on by sajjadaghazadeh
Hi sure; Ball mill 1: 700kw with current working amper 1000 A average. Product size D80:45 micron. Critical Speed 75-80%. Ore work index 12kwh/t. Solid percent 70-80%. Ball mill charge 40 and 60 mm. N...
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Started by Solaris1987
Hello In our iron concentrator plant we use a wet ball mill for grinding of fresh feed. It operates in a close circle with hydrocyclones. The overall data of ball mill and hydrocyclones are following:  Ball mill: F80: 4 mm Diameter: 5.5 m Lengt...
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Last replied to by Robert
You might find this approach (see article and webinar) useful.   >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>...
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Started by banyechan
what reasons for the increasing ball consumption after converting my overflow mill to grate discharge mill?
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Last replied to by Robert
From SME Mineral Processing Handbook, Ed. N. Weiss, SME, 1985, page 3C-28 and surrounding article on grinding: “In grate-discharge mills, due to the lack of pulp in the zone just in front of the gr...
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Started by facostam
Hello 911MetallurgistI am currently working on a concentration plant, specifically on the liner change of the ball mills. I have to determine the difference in wear behavior between mineral (copper sulfide)-steel and steel-steel, all this according t...
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Last replied to by Miguel
Hello Francisco, It's quite evident that if you run the mill at a low tph as it is being designed for and at a high rpm it will be quite certain that the contact between steel liners to steel balls w...
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Started by Hauptsturm
How to increase the density when too much material is reporting to the cyclone underflow? Is it the right practice to increase the density when too much material is reporting to the cyclone underflow for a diamond processing plant? Cyclone pressures...
Last replied to by
I presume we are talking heavy media cyclones here? If so then you should increase the medium density to reject a higher proportion of light minerals to the overflow. But as with everything there is a...
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Started by courio
Hello friendsWe have a problem to solve and a conclusion that I do not think is the reason.MOLINO BALLS DOMINION (4X72metros D by 6.4metros L) 2300KwThe mill is supported by a pair of hydrostatic bearing journals (2159 mm diameter x 483 mm wide), equ...
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Last replied to by Robert
Is this a recent change? Previously were there any concerns with maintaining ball charge? Would you describe past behavior before this problem originated?  
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Started by richardh
Hi I am trying to build up a library of papers on the function of a hydrocyclone in a closed ball mill circuit and not as a means 'of doing any grinding'. I am often faced with the question "We have a grind of 'A' micron in our ball mill circuits b...
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Last replied to by Robert
Not knowing your situation re accessing technical literature? For some additional details look at: Seitz, R.A. and Kawatra, S.K., Further studies on the use of classifiers for the control of wet gri...
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Started by nyala89
I need some help. We need to mill ocher as fine as possible. To date we used an outdated Raymond mill. The company bought a small ball mill about 20 years ago and we would like to use it in our process. Do you think that with the ball mill, we would ...
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Last commented on by nyala89
Thanks Wayne for your comments. I will really put it on the table.
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Started by jovanifirebird
hi guys. i am working at a small scale mining industry. they have been operating at about 80t/h feed to ball mill. the cyclones operates at about  85MPa feed pressure. 2 cyclones run at a time. however they don't maintain water balance .we all know ...
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Last commented on by jovanifirebird
Thanks for the suggestion ashutosh. But I dont think u understand the problem. My cyclone feed percent is 55%. But that works out when feed is 90t/h. If feed goes down to 40 t/h , you cant do the corr...
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Started by Jean Rasczak
Hi, A lot of this is just theorizing. We will have to try the ore out to know what sort of grind we really need. But, that said, there are several potential issues. Zinc, according to the initial feasibility test work needs to be reground in order...
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Last replied to by Dave Tahija
If high pH of the cleaner tails is the only issue preventing sending them to a flotation/tin stage, why not lower the pH with carbon dioxide?
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Started by babygenius76
I have a West African project where we use a pendulum roller mill along with classifier to dry-grind high purity (95% to 98%) calcite to d50 10 micron with a relatively steep PSD curve.  The top feed size into the mill is 5000 microns (5 mm) because...
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Last commented on by babygenius76
Robert, Yes, the grinding from 5000 to 10 microns is highly energy intensive. As you see above, I have even tried a 2 stage grinding where in the first stage, I reduced it from 5000 to 74 micron. In ...
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Started by georger
Anyone have access to a operating manual or any documentation for a Vickers Ruwolt 48x20" Rolls Crusher? 
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Started by polyroly
Good Evening Everyone. First time posting in the forum here! We just recently relined our SAG mill and we have had some operational issues since starting back up. We have had a massive amount of filings ending up in the discharge magnet and I examin...
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Last replied to by dassahd
Sorry I am late in joining, does it happen during every startup? If yes then I recommend you do as Alex suggested. You may need to test the balls as well. Probably adding a new batch to the mill.
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Started by Okay
Hello Everyone, I am dealing with the calculation of Bond Work Index. The flowsheet is attached. I have calculated primary ball mill bond index but for the calculation of second ball mill bond index I got trouble. In a bond energy equation,  where ...
Last replied to by Alex Doll
F80 is the feed size to the primary BM; T80 is the transfer size (prim mill product size), P80 is the final product (cyclone overflow) The F80 is the feed to the primary ball mill. The T80 (is t...
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Started by Nicolau Ismael Lazaro
Hi all. I am new in mining industry and I have two task to do and I would like your help: Perform Reflux Classifier Capacity Test and; Optimize the Reflux Classifier Performance Can the anyone give some insight on how to do this tasks. Thank y...
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Last replied to by Nicolau Ismael Lazaro
Thank you Rahil. I would like to get optimum parameter (bed density, fluidization and feed flow rate) for the reflux classifier processing -1.0 +0.25mm particles from the deslime screens to get produc...
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Started by Hamid72
Hello everybody In our plant sometimes freezing of the charge happens for the ball mill and if we cant solve this issue after three times the ball mill will be stopped for 5 hours. I want to know why this issue (the load cementing) happen? And what ...
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Last commented on by Hamid72
hello David. thanks. when the ball mill stops suddenly for example because of the high temperature of the oil and we cant run it for half an hour frozen charge happens.

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