Grinding & Classification Circuits

Grinding & Classification Circuits 2017-04-04T06:57:16+00:00
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Started by Johannes
We are attempting to successfully grind Micaceous iron oxide (Hematite) down to -63 micron average 40/50 micron but maintaining the bulk of its lamellar structure,platelets after grinding should show up red under a bottom lit microscope, any one had ...
Last replied to by AJNeale
Hi Johannes - I don't have any direct experience with this, but if "micaceous" and "lamellar" mean that your are liberating flat platelets, then you might think about separation using a shaking table....
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Started by Langton
Am looking to design a 4 to 5 ton per hour dry ball mill. What factors should I be looking for? The following is what I have: Feed size 20mm, product size 75microns, Wi 16.5kWh/ton.  I do not what want to use any water as its washing away a lot of ...
Last replied to by Langton
Thanks for the advice Andrew. We do have a concentrator on the site but still the gold is being washed away after stamp milling to -2mm. There is also water issues on the site hence we looking at amal...
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Started by Tony Johnston
Does anyone have a couple of examples where iron ore is being ground using a ball mill with an inverter for mill speed control? And if you do, can you offer any commentary on how successful, in technical and economic terms, that approach is proving ...
Last replied to by David
My friend from https://sagmilling.com/ says most iron ore mines don't use ball mills for a couple of reasons: 1. The grind is coarse enough that you can do it in a single stage (Eg. Labrador Trench) ...
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Started by Simeon
How long would a hydrocyclone typically last (Barrel, lower cone, mid cone, spigot) before being worn out? It can be rubber lined, Polyurethane whatever material... When feeding rough like d50 1mm - 4mm ?  High pressure range 90 - 120 kPa  F...
Last replied to by czambrano
Interesting and useful comments. Something to take into consideration specially with high pressure cyclones and coarse material is the underflow launder lining, which finally could shutdown the circui...
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Started by vekian
Hi people. I've put this idea by 2 metallurgists at the gold plant I work at. 1 agrees with me that it is worth trying. The other disagrees. They want a COF density target of 46 with a SG of 2.7. Extra water is needed to be added to the mill discha...
Last replied to by Dielgarcia
Vekian: Hi, can you tell me the thickener u/f?, if you have 46% in the COF, but, what density have in your CIL tanks?
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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 KLKJNB
If you're interested in a mill similar to that, I would contact Amoref from South Africa. Their rod mill follows a similar idea of a couple large rods/rollers in a smooth lined rod mill.
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Started by Pabloski
Hello everyone, After the SAG mill there is a SAG box, where the output of the SAG is transferred into. There are 4 pumps (2 operational and 2 in stand-by) that transfers the material to a cyclones battery and then to two ball mills. When the ma...
Last replied to by kam81
Using an intermediate chute or box to evenly distribute the feed into the pump box could help. The main problem however is the floor slope and suction locations. If you don't mind losing some volume ...
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Started by mohamedkrafi
I want know if you have an idea about the best  comminution circuit selection basing on Ore hardness and competency (SABC, AG, ROMBALL MILL) we have two type of ore compétent and hard (AxB=24, ball work index = 18) and moderate and soft  (AxB=40,...
Last replied to by Robert
There has been a good discussion of this subject in recent years. Much of this has been summarised in a matrix fashion with axes the major factors to consider and secondary factors discussed within ...
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Started by THIRU
Dear sir, We need grinding machine for grinding scrap of iron mill scale chips in size 25 mm width, thick 2 mm can be reduced into 1 to 2 mm powder. Also the iron mill scale chips contaminated with some another hardened iron lumps may thickness 10 ...
Last commented on by THIRU
1.5 M.T / Hour
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Started by Fabian Rebolledo
I would like to know if there is some technologies that can measure the mass flow of an open channel that carries pulp from grinding and feeds milling
Last replied to by OberstGruppen
Fabian, What are you trying to achieve?
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Started by sajid
My grinding mill has length and diameter of 4.57 m. the maximum size of the balls selected is 77 mm, as there are two or three kinds of ball sizes used..how to select the second ball size. are there any formula or equation that i can calculate the ba...
Last commented on by sajid
thanks for valuable information. i already calculated it for the first charge. but now i need calculation for the second charge. if you could give me some guideline it would be appreciated.
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Started by Helena Russell
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 were a bit down but within specs, manual and instrument densities were right but still too...
Last replied to by David Kano
If cyclone feed pressure and operating density are within acceptable ranges, you might want to have a look at the media density differentials. By measuring the feed and overflow stream densities you c...
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Started by AR
How to decrease Copper lost in tail and what should upstream plant (grinding) to do to decrease Cu lost in tail ? Thanks you
Last replied to by Robert
Root cause analysis would be good preliminary before altering grinding conditions.This is working to understand what particles are being lost. Suggest sampling feed, con, tails, determining size...
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Started by SAKAR
Dear Friends, Hi....I have one question about type of Wear Resistant Liner for Grinding mills. Why & Where to use metal Liner & Rubber liner ? I want to know about type of Grinding Mill Liners and where to use it.... Thanks & Good day. Jignesh
Last commented on by Alex Doll
FYI, the attachment Stuart provided is a chapter from the SME "Advances in Comminution" (Ed. S.K. Kawatra). It is a great book and I would recommend anyone interested in comminution pick up a copy of...
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Started by AR
What corellation between efficiency hydrocyclone and valuable mineral lost in tail? What corellation between grind size P80 overflow product of cyclone and valuable mineral lost in tail? Thank you
Last replied to by Zander Barcalow
In a rougher flotation circuit: if you are more than 55-60% liberated on your target mineral = a coarser or finer P80 will not immediately matter. If you are say 80% liberated = coarser P80 may red...
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Started by Romain CADENAT
Dear All  I have a hydrocyclone for which I need to send the overflow +1.5m above the head of the hydrocyclone. Is this configuration possible ?  On the file attached I show standard configuration and the one I want. The feed pressure of the hyd...
Last replied to by Romain CADENAT
Ok, thank you for your help Andrew.  Thank you for the links Jean, interesting. In fact it is not a grinding circuit but a classification line. 
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Started by Ibrahim
Hello, We measured the thickness of sheet plate and lifter bar rubber liner in a ball mil for a gold mine to estimate when we have to change them. What is the minimum thickness of sheet plate to preserve the drum of the ball mil? And what is the mi...
Last commented on by David
It's about time you show up Stewart 🙂
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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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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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339
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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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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 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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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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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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