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Started by joy1484
We started our hammer mill (Williams mill) after doing several maintenance to solve some electric problems. The plan was to get in spec and then not make any adjustments and watch grind. With a starting grind of 76 (spec is 74-86) we let the mill go...
Last replied to by Robert
Did material sit in the feed hopper/silo during maintenance shut? When you checked for obstructions did you check to see if flow from feed silo? 
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Started by AR
What the correlation between throughput and grind size, throughput and power utilize, throughput and ore characteristic (WiBM), grind size and recovery Cu lost on tail? Thank you
Last replied to by AJNeale
Hi AR - Max and Bob have summarized it very well.  In terms of optimization you need to relate metal production to metal recovery, throughput, and head grade, where metal recovery is a function of gr...
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Started by Josh Wright
How does a "modified bond ball mill work index" test vary from a standard ball mill work index test?
Last replied to by Josh Wright
Hi Dave, Peter, Chris, and Greg, Firstly, thank you so much for taking the time to reply. One of my colleagues mentioned that a recent RFQ requested a modified bond ball mill work index. We had susp...
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Started by Takue
I need help in the determination of the power drawn by a wet pan mill in gold milling
Last replied to by Alex Doll
Short answer is you measure the root-mean-square Amps and Volts going into the motor driving the mill, correct for the motor efficiency (and possibly power factor) and calculate power using equation P...
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Started by SAKAR
i am designing rubber lining for ball mill with below given operating condition can you please suggest me approximate thickness of shell liners and lifter bar ? OPERATING CONDITIONS: 1. MATERIAL                           ...
Last replied to by David
Same profile. Just increase the spacing at the shell/head joint. See this photo of inside a ball mill and its liner arrangement.
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115
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Started by Shahid Rind
We are making silica  flour in ball mill but production coming too much down because the main blower amperage downs from 50 ampere to 30 amp after giving feed material. I also checked the classifier, main blower motor, filter but still did'nt find ...
Last replied to by David
Have you closed off a duct? Amperage goes down as resistance to airflow increases. It is like free spinning. Is it possible the material you are feeding would block/restrict the airflow intake to you...
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226
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Started by Shahid Rind
How do I increase d 50 value for caco3  45 micron in ball mill? What are the parameters for ball mill to making d 50 value 10 to 13. We are running CaCO3 45 um in ball mill but D50 value is not increasing more than 8 for making more coarser. I also...
Last replied to by Sugar Watkins
Shahid Rind answer the questions we need to help you and try increasing your classifier density. Read https://www.911metallurgist.com/blog/spiral-classifier-for-mineral-processing and https://www...
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Started by mohamedkrafi
Dear sir; I want to design the ROM ball mill  (it's same of ball mill  but it can accept the big size until 150mm): are there some process  limitation for this technology? is it possible to design ROM ball mill (1 stage) from D80=100 mm to ...
Last replied to by AJNeale
Hi Mohamed - I can't disagree with anything David has said.  I see an increasing interest in ROM ball mills.  Their popularity is due to the lower capital cost, i.e. one primary crusher, one mill fe...
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Started by levina pangani
I want to optimize the grinding circuit so as to improve gravity and grind size. What may be the main factors should I consider in order to achieve my project. The recirculating load in the plant is 400% and type of the ore processed is the mixed sul...
Last replied to by Charlie
https://www.scribd.com/user/161408287/Cristian-Dosque-Munoz
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Started by Alan Carter
what is better for classification of copper up to 75 micron size whether to use spiral classifier or hydrocyclone
Last replied to by David
A friend familiar with this told me the main problem with spiral classifiers is the cut size is directly proportional to retention time (flow rate, Stoke's law, that sort of thing). To get a fine c...
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Started by mohamedkrafi
I have lot of scats in overflow ball please help if I transformed overflow ball in grate discharge ball mill I will less scats production  or not? (D80=10mm, P80=140 microns)
Last replied to by Khosana
Hi Krafi, I would suggest that you firstly study your feed PSD vs ball charge size distribution before opting for the alternative. Plus I'm not sure if a grate discharge will give you the same grind...
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270
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Started by glocmines
Does making the ball mill close circuit, reduce its P80. (e.g letting the hydrocyclone produce an overflow of 130 um). this would mean, most of the pulp will go to the underflow. If we do this, what is the limit for the circulating load? The proble...
Last replied to by Jorge Ganoza
There are some aspects you should consider in your design. Your ore is very soft, it means that the non-sulphide gangue minerals would be reported in the copper rougher concentrate. For that reason, i...
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Started by Venkatesh
Propose to employ free floating grinding roller instead of balls or rods in a ball mill. Can we run the mill at 150 to 200 percent critical speed? How to assess the mill drive power in this case? Any formula? Air flow through the mill can be up to 4 ...
Last commented on by Venkatesh
Mechanically, it is a dry grinding rod mill overflow trunnion discharge type. However, grinding rods are replaced by equivalent weight grinding roller.
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Started by ricardo.pascor
If I have a ball mill 6x12, I wish to get better energy consumption, then It is possible to get when I change the trunnion bearing by roller bearing for mill grinding application? If it is possible, which is the percentage (%) to save from the act...
Last replied to by raghdmuhi
dear, I didnt understand the question.
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352
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Started by randzzzzzzzzzz
How did you derived the formula for the critical speed of the ball mill?
Last replied to by
When the ball mill rotates at the critical speed the theoretical trajectory of the charge is such that it would fall outside the shell as centrifuging occur at this stage and the medium is carried aro...
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Started by soheil8
hi dears.please help me. Are there iron ore concentrate plant that use pebble crusher in circulating load of AG mill? thanks.  
Last commented on by soheil8
Ok.
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169
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Started by Hauptsturm
I am currently working on a study with a client on alternative Grinding Circuit energy intensity quantification methods based on the approaches in http://www.ceecthefuture.org. I came across your articles https://www.911metallurgist.com/blog/bond-i...
Last replied to by Alex Doll
Short answer is yes, the SMC test is one way that you can "benchmark" an operating mill against a theoretical power consumption for a "typical" grinding circuit. There is another method using Bond-ty...
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Started by kocgium
Hi guys, I am new in the mining world, yesterday i was in a meeting with a lot of metallurgist, and all of them agree with this sentence:  " we design the plant so that grinding/milling area is the bottleneck " Why is that or why the bottleneck c...
Last replied to by AJNeale
This is a very good question - and one that is often not fully understood outside the processing fraternity.  The basic answer is that it is because the grinding circuit in general has the highest ca...
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Started by jaquil
single stage grinding in gold processing plant. using ball mill. a simple flowsheet of it is humbly needed.
Last replied to by jaquil
Thank you for the respond ^_^ 
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Started by alzhrani a
hello every one 1- i am working in gold plant and my co-worker calling the sag mill Pebble mill and i searched in google then i found sag mill is not same as  Pebble mill if you can help me and explain the different  to me i will be happy. 2- i...
Last commented on by alzhrani a
Thank you mr dk
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296
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Started by Subhash-Kumar-Roy
Yesterday I calculated the power draw of our ball mill. I attach a graph of it.  Is it possible to have calculated mill power draw to be greater than mill motor HP? Calculated mill power draw is 1,509 HP Mill motor HP is 1,500 HP  Accordin...
Last replied to by Subhash-Kumar-Roy
Thanks everyone.  I realize I had forgotten to detect the mill liners from my mill's dimensions. Therefore yes, my model was incorrect. This change results in a in the diameter going from 13.5 ft to ...
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Started by maino.kaupa
What can i do to get best grind sizing in the mill: add water? decrease water? add more balls? Speed up mill? or what more to do?
Last replied to by David
Also see https://www.911metallurgist.com/grinding/interpretation-of-power-draw/
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Started by banyechan
What are factors causing the balls out of roundness in grinding mills?  
Last replied to by MillMan
What is the original ball size, 130 mm?  Who is your supplier?  This is a photo a what? What are all those balls located? + Did you actually read the 3 PDF I gave you?
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Started by banyechan
Why should high chrome casting balls be only choice using in Platinum ore grinding? We know that both forged and casting balls are used in gold and copper mines, but we are wondering why the high chrome casting balls only choice in Platinum? Could ...
Last replied to by MillMan
A study has investigated the effect of using different milling media on the ultimate flotation performance of a UG2 ore milled in a laboratory tumbling mill. The results showed that the different me...
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Started by vekian
Is there a table/explanation/diagram or similar that exists online that explains in a simple format, how to interpret a graph/trend of power draw/KW/load. eg. what the trend/graph would look like if a ball mill has too much or not enough water, or if...
Last replied to by vekian
Thanks fellas for the quick replies. And thanks Paul. This link was something like what I was looking for. Simple for a new/inexperienced person and easy to explain in a non-technical way. https://www...
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Started by Takue
How to compare a ball mill and wet pan mill in terms of energy consumption and efficiency in gold processing.
Last replied to by David
Hello Takue and welcome to the forum. You know Arrastres, Chilean mills, and Huntington mills are types of pan mills. A Hardinge mill is a type of ball mill that was around in the days of pan mills...
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Started by jamesd
How to establish a mass balance and derive the circulation load of a closed circuit given the specific gravities of the mill discharge to classifier, underflow and overflow from the classifier? An iron ore company milled ore at the rate of 150 t/h i...
Last replied to by Bill Fraser
I need lots of details on your situation...otherwise just read https://www.scribd.com/doc/293372742/Mineral-Comminution-Circuits-Their-Operation-and-Optimisation-T-J-Napier-Munn-S-Morrell
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Started by New Era
Can you help me to calculate my ball mill power draw daily.  
Last commented on by New Era
Is it the gross power or the net power drawn by the charge
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Started by Maya Rothman
Hello, in calculating the top size of grinding media for a ball mill, there are 2 methods/formulas (Fred C. Bond) and AZZARONI's. Am looking at a ball mill F80 1248um and 8m diameter, 78% Cs, BWi 14.3 and SG 3 Azzaroni's ball calc is almost 2X the...
Last replied to by Greg Henderson
  Alex Doll is right in that these equations are based on empirical data and experimentation or benchmarking with mills processing similar ore is perhaps more practical. Another consideration is re...
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Started by Arnmax
i am planning to check the efficiency of a primary cyclone that is used at a processing plant, so i would like to know what parameters should i check in order to determine its efficiency.
Last replied to by johnclark
As well as taking samples and determine the hydrocyclone efficiency, I'm inclined to revisit the original cyclone design to see if your cyclone is in the right ballpark for cyclone size/shape/etc. (c...
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Started by JOHN
Hello guys. I really need your expertise advice and ideas.  The plant I work for is a gold processing plant. They have a real problem with the pumps from cyclone underflow to ball mill. The mill section comprises a ball mill, screen and cyclone. I ...
Last replied to by johnclark
Hi John. Until you get things running back to normal, how about trying more steel balls in the ball mill. Could you get your hands on a more resistant pump liner quickly. Can you possibly reconfigure ...
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Started by jerry andoh
Currently my SAG mill load cells aren't working so the quest is how to run the mill with only power draw indication. Assistance will be much appreciated. Jerry
Last commented on by JLIn
Normally discharge end trunnion lub pressure has really good correlation with mill weight(load cell reading), we used to to use the reading to confirm the reading at commissioning.
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Started by Charlie
Hi, If I calculated the grinding ball I need on this ball mill grinding circuit to be about 1/2 the diameter of the ball this mill is already using, is there a way to estimate the grinding efficiency gains I could expect of switching to that smalle...
Last replied to by LBERNAL
Some comments according my expertise:- Although most of primary mills are using bigger ball size that they need, I see difficult a drastic change to the half size- Depending of the feed PSD and hard...
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Started by mlticzon
What is the most reliable method to determine actual circulating load in grinding circuit? A simple one - ball mill w/ hydrocyclone.   I observed that the most common methods applied are (1) use of water balance - taking samples of cyclone feed, c...
Last replied to by David
Hi mlticzon, Welcome to 911Met and thanks for this useful question. This is one of those learn by reading/doing/trying. Have a good look at https://www.911metallurgist.com/blog/moly-cop-tools-downlo...
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Started by Gh99
I am a new in an iron ore plant were we are with magnetite ore using two Aerofall Mills but it's very hard for us to control the the mill feed rate, and we also have a problem with the Ball charge; we've tried different charges but it's still a prob...
Last commented on by Alex Doll
Big rocks need big balls to grind effectively. Small rocks need small balls to grind effectively.

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