Grinding & Classification Circuits

Grinding & Classification Circuits

  • To participate in the 911Metallurgist Forums, be sure to JOINLOGIN
  • Use Add New Topic to ask a New Question/Discussion about Grinding.
  • OR Select a Topic that Interests you.
  • Use Add Reply = to Reply/Participate in a Topic/Discussion (most frequent).
    Using Add Reply allows you to Attach Images or PDF files and provide a more complete input.
  • Use Add Comment = to comment on someone else’s Reply in an already active Topic/Discussion.

1
REPLY
31
VIEWS
Started by Vedant
The throughput is known. Amount of water adding to the rod mill feed is also known. Can we calculate amount of rejects through rod mill. If we can, how & what other info is required?
Last replied to by Mike
A rod mill is a comminution (size reduction) unit, it is normally followed by a processing unit that produces 2 or more streams.  One of these streams maybe listed as a rejec (tails) stream.  Measur...
1
REPLY
59
VIEWS
Started by Shivani
How can we calculate the power of a SAG mill in a SAB circuit for a greenfield project. From Morrell's Power based equation, we can calculate the total energy for the circuit, but how can we split the energy between SAG and ball mill from the total e...
Last replied to by Mike
The simplest method would be to use stabdard SAG and ball mill energy calc and then subtract from the total. To calculate SAG and ball mil energy see  SDM Mill Calculations: Perform ball, rod, pebb...
1
REPLY
153
VIEWS
Started by rakavka
Hi guys, I have to calculate a new throughput of the existing grinding circuit with a new finer ore.  I'm trying to calculate a BM working index of the new ore with 300 um sieve size. The problem is that amount of undersize in feed is higher then...
P
Last commented on by rakavka
Hi Alex, I eventually used Magdalinovic rapid method which by-passes the fines problem. Isn't it opposite? the smaller the sieve, the higher Wi? For a finer product we need to put more energy..? Than...
1
REPLY
133
VIEWS
Started by BrendonTop
We are to put in place a Ore intermediate storage before feeding the mill and have to select between mill Ore shed and a Silo. If there's anyone informed in both please assist.
B
Last commented on by BrendonTop
Thank you for your feedback.
1
REPLY
127
VIEWS
Started by BrendonTop
Been looking into the advantages of using Clutch driven mill over a gearbox driven mill. If there is someone with experience with both can help shed some light on both cases.
B
Last commented on by BrendonTop
Thank you.
2
REPLIES
130
VIEWS
Started by BrendonTop
I have ore with high black shale and direct leaching is giving up low recoveries some as low as 9%. Is there any way of improving the leaching process?
B
Last replied to by BrendonTop
Thank you very much.
1
REPLY
263
VIEWS
Started by Jonnie
Hello, I have a Denver Mineral Jig model 8"x12" Duplex. It is powered by a Baldor 3/4 HP, 208/230 Volt , 1140 RPM, 3 Phase. With a shaft size: 7/8" diameter, 2.5" long with a Woods MS-72 variable sheave.  My problem is, I don't have access to 3 phas...
J
Last commented on by Jonnie
Thank you for responding. I solved the problem by adding 3 phase power to the shop which also gives me more options for the future. Thanks again
1
REPLY
231
VIEWS
Started by Mustang
Hi, I want to know if anyone have utilised the Intelligent Bolts (iBolt ) in any of their mining operations for the condition monitoring of their sag or ball liners? The ibolts monitors the wear of the liners. I am trying to look for case studies on...
d
Last replied to by David
I would never entrust such an important measurement to an "Intelligent Bolts" - NO. Just like 'smart phones' make the user dumber.  Imagine you trust your Intelligent Bolts and walk into a SAG mill...
1
REPLY
215
VIEWS
Started by John KK
Dear All We recently changed from a steel wave liner to a rubber liner with lifter in our ball mill. We have noticed an increase in the amount of scats. Are there any considerations that we need to take into account with the change in liner, such as...
d
Last replied to by David
New rubber liners = initial increased lift = increased ball breakage
1
REPLY
227
VIEWS
Started by Mustang
I want to ask what is best practice for liner change out or what is the most suitable for both Sag and Ball mill ? Would it be time-based liner change out during planned shutdowns or liner wear rates should be tracked instead ? if liner wear rates ...
Last commented on by Mustang
Thanks!
1
REPLY
221
VIEWS
Started by EAKUVI
I meant what do.you do when your overflow density is high?
Last replied to by Mike
Add more water to feed
1
REPLY
255
VIEWS
Started by richardh
Hi  I am looking for online cyclone sizing software. I see the Multotec sizing software here but was wondering if any of the other cyclone suppliers have an equivalent software that they supply? Multotec Login (b2clogin.com)
Last replied to by Mike
I have some (plus other pacalages) that are excel based here: https://www.smartdogmining.com/software/  
3
REPLIES
280
VIEWS
Started by tony.difeo@nrcan-rncan.gc.ca
I have to grind a ore sample (1 kg at -6 mesh) to 80% passing 300 microns using a lab rod mill.  However, I am getting inconsistent results.  For a set time to achieve 300 microns determined from the grind curve, sometimes I get finer than 300 micr...
d
Last replied to by David
Hi Tony, in that case, I would review every detail: Has sample splitting of the crushed product been done to 'perfection'. Is the screen/sieve analysis (on the crushed and ground products) done b...
1
REPLY
958
VIEWS
Started by Metals Guy
Does anyone know of any plant operating with an automated Single stage SAG milling circuit most preferably in Africa. If there is anywhere else besides Africa be free to tell.  
b
Last commented on by bwalya chansa
David you have made me laugh
2
REPLIES
630
VIEWS
Started by Vinzo 3111
the derivation of the formular of ball load from basic principles
Last commented on by Mike
Sounds like a class room problem. Besides, insuficent info. Need size distribution of mill discharge and screen size openings.
1
REPLY
316
VIEWS
Started by chez2204
Hi, when i mill the powder by grinder(stirring, samll size, 50% fill rate), with balls, i can see the effect of grinding aids. But when i change the grinder to ball mill ( big size), it seems to that grinding aids  don't work, same ratio(ball/samp...
Last replied to by Mike
You are not operating them under the same conditions(10% vs 50% fill) so yes the parameters will affect the performance.  Also a stirred mill vs a tumbling mill (inferred from your question) operate ...
4
REPLIES
333
VIEWS
Started by EAKUVI
Does too much fines in you final feed product to your mill cause high mill weight? 
d
Last replied to by David
We can't help you if you don't answer the questions. What is your power draw VS what you have installed on the motor?
1
REPLY
323
VIEWS
Started by EAKUVI
How does less steel balls in a ball mill affect cyclone pressure
Last replied to by Mike
Decreasing the balls in a ball mill will have the tendenacy to increase the average size of the mill product.  While this will have no direct affect on the cyclone pressure, a coarser feed will impac...
3
REPLIES
424
VIEWS
Started by chez2204
Hi everyone, I want to determine the size of steel ball, according to the equation of Bond and the equation work index: W=WI* (10/√P80 -10/√F80), for calculating Wi,  I need to konw the W(work input,kwh/metric ton), so how can I obtain the work ...
z
Last commented on by chez2204
thank you
2
REPLIES
449
VIEWS
Started by Siaka
It's that I ask if someone can help me with ideas when we are in front of a mineral which is sticky and which must be milled by a SAG mill
d
Last replied to by David
what do you mean by sticky? where does it stick? In the mill between liners? In the feed chute or conveyor transfer points? pictures?
2
REPLIES
508
VIEWS
Started by Miigaa
Slurry material ground in a SAG mill feeds two ball mills in the grinding circuit. Which means one pipeline divides into two pipes through distributor (similar to cyclone pack head). Mostly, distributor could not allocate the slurry flow evenly, so t...
Last replied to by Mike
As to high volume and large particles, pinch valves can be used.  You generally will not get 100% shut offf so other valves (gate) are needed for mintenance.  Also pneumatic actuating is best as can...
1
REPLY
652
VIEWS
Started by Ceverett
Just wondering if anyone has a ball or SAG mill with a trunnion magnet to remove scat steel and if they are willing to share the results. Looking into getting one for our SAG mill but looking for proof that it actually creates power savings, ball con...
Last replied to by Mike
Trunnion magnets will work, unless you are using steel balls or grinding a magnetic ore.  Since the magnet will pickup magnetic material, they will pickup scats (ball pieces and chips) and balls that...
1
REPLY
602
VIEWS
Started by Pommy35
Hi folks.  we seem to have s bit of a debate on my plant. When grinding out your ball mill, if the mill power draw (KWS) struggle to rise above lets say in this instance 2180kws but you are hoping to achieve 2250kws. Does this indicate the mill is ...
Last replied to by Mike
Power draw is based on total load, charge plus feed, and then grindability.  If the feed is achieving the proper grind size with a lower power draw it could be that you are under feeding and/or the g...
2
REPLIES
840
VIEWS
Started by Ceverett
In our grinding circuit, we have a SAG mill that uses rubber liners. Once the liners are worn out and replaced we sell the old liners to a company for a credit where I am guessing they either burn them or leach them in a tank to recover the gold embe...
F
Last replied to by AAFilipe
Honestly, this is not a thing that you should be worried about. The gold content on liners won't make that difference to you, while to recover it you would have to invest in an equipment that is not ...
1
REPLY
701
VIEWS
Started by Dewald
Hi. can someone assist me with a few problems I have? We have a overflow dry grinding ball mill grated discharge 2.4m x 1.5m, we use 40mm,25mm and 17mm ball sizes (high chrome steel) to mill manganese with a top size of 4800um, mill liners are stee...
B
Last replied to by Dewald
Sorry mill is 2m x 3.4m
1
REPLY
821
VIEWS
Started by Sam_123
Hi everybody, I want to calculate the mass moment of inertia of ballmill inorder to correctly size my motor & to calculate the starting time of motor.could someone help me. Thanks
Last commented on by Mike
This is multi term integral based on a specific mill configuration. You would need to develope this for your mill based on the mill drawings, assumed charge and momentary feed rate. There is no gene...
1
REPLY
812
VIEWS
Started by SDG
Hi Everyone,  I am interested to have your opinion on dry grinding/ air classifier circuits. Specifically, how would you approach mass balancing on the following attached exmaple using a 2 air classifiers with a mill/ HPGR placed in between (a simp...
S
Last replied to by SDG
Hi again everyone, sorry there was a mistake on the block diagram before. The correct one is attached herwith. Thanks for your opinions and cheers!
1
REPLY
960
VIEWS
Started by Gallo
equation to calculate the mill weight using mill charge level and load cells
J
Last replied to by Jorge
Nowadays, probably, the best systema to measure the load is to install load cells. It is necessary to indicate that the load cells are calibrated to measure the total weight of water, steel balls and ...
2
REPLIES
899
VIEWS
Started by Ceverett
We have a problem with scat steel buildup in our gold gravity circuit and are looking at solutions to remove it for a steel buyback program. One of the ideas discussed was getting a new screen installed for our cyclone underflow and installing a belt...
S
Last replied to by ManUtd67
From a metal recovery perspective a good idea as metal is well presented to the magnet.  Issue is any steel will become magnetic.  Have done this before with stainless on the discharge of the screen...
4
REPLIES
840
VIEWS
Started by Fuloshixwa
I am failing to measure my DMS vortex finder length during maintenance day because it quite difficult to access from the spigot end. Any suggestions guys?
Last replied to by Mike
For most cyclones the overflow discharge is bolted to the outlet which is the vortex finder.  Removing the overflow pipe you can easily measure the diameter and then reaching inside you can measure t...
1
REPLY
908
VIEWS
Started by evandewitt
Our wet Ball Mill griding media reject (scats) from the trommel screen is an odd shape ( see photo attached). I’m not use to this wear shape of grinding media in a ball mill. Normal wear of grinding media in my experience is down from a spherical t...
d
Last replied to by David
And what is your question exactly? octagon/nonagon shapes ball leftovers are the result of a soft inner core - 55 to 59 Brinell. spherical to a non-spherical (egg shape) will result from a harder co...
1
REPLY
867
VIEWS
Started by Steve
We recently converted our metso 18X11 steel lined Rodmill to rubber lined trommel discharge Ballmill to improve grinding efficiency and increase throughput. Our rodmill used to run 120 tons/hr at a critical speed of 61.5% with rods diameter of 3".  ...
Last replied to by Mike
There are many factors that impact on mill sizing and performance that you do not mention, particular grindability, desired product size, open or closed circuit, wet or dry grinding, what material you...
4
REPLIES
1673
VIEWS
Started by Fuloshixwa
I am sizing a cyclone for slime removal for a new plant but I am struggling to determine ideal operating conditions such as feed velocity, feed pressure and pulp density. I am thus looking for article referrals. Or sites where I can download them for...
J
Last replied to by jbessett
I was wondering if someone could explain the input parameters for https://www.911metallurgist.com/blog/hydrocyclone-design-equations-and-sizing-parameters-calculations ? Or perhaps the design equatio...
1
REPLY
950
VIEWS
Started by Fuloshixwa
How do I do material balance on an open classification circuit with a cyclone as a classifier. It is a desliming cyclone with the underflow as my concentrate and the overflow going to the tailings dam. Any piece of literature out there I can consult....
Last replied to by Mike
Regardless of the equipment type, material balances are calculated the same.  See: https://www.911metallurgist.com/blog/metallurgical-accounting-formulas  
2
REPLIES
2970
VIEWS
Started by ManUtd67
Interested in opinion on whether to install a pre-leach thickener ahead of a gold leach circuit or operate cyclone at higher density. Option 1 - Cyclone O/F at 35% solids, P80 75um.  Thicken to 65% solids and dilute with tails thickener O/F (cyanid...
r
Last replied to by rob riggir
Hi, It is better to go with the preleach thickener as long as you have the project life to get payback. You will then be able to operate your mills and cyclones at optimal densities and increase tan...

Please join and login to participate and leave a comment.