Grinding & Classification Circuits

Grinding & Classification Circuits2018-06-17T09:51:34-04:00
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Started by Obersturmbann
A few years ago, McGill University in Canada developed a new and more accurate test methodology for predicting steel media consumption. This test (Steel Media Wear Test) is licensed and currently being offered commercially by JKTech. The test also ha...
Last commented on by MSKabir
Has the papers been published ? Could you kindly provide links to the research papers or source.
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Started by msammet
Hi all,Please can you help me to find standards for design and sizing ball mill (calculation of thickness of shell , Ø of shell , ... ) ?best regards
Last commented on by ABS
Hello Msammet, im also facing the same problem. do you manage to figure it out. i want to design a 3-5ton/hr ball mill for gold ore but i dont know where to start from
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Started by
Which is best for economics of grinding media do you think: High chrome steel balls and forged steel balls.I would like to know if anyone has an idea or paper on the benefits of high chromium steel balls over the forged steel balls. 
Last replied to by banyechan
In SAG and BM,it is better to choose forged balls in wet working conditions.
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Started by
I’m interested to know when sizing a new ball mill, as to why recirculating load has no effect on the power calculation, although it will have effect on volumetric capacity naturally. For instance a mill of 300tph with a 300% recirculating load wou...
Last commented on by David
look around https://www.911metallurgist.com/blog/eq
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Started by Oberstorm
A laboratory grindability test made in closed circuit. Should it be regarded as a miniature of a commercial mill operation? Should its performance be scaled- up to the size of a commercial mill?Does the screen analysis of its product and circulating ...
Last replied to by
Closed circuit milling at small scale (Bond mill sizes) provides opportunities to simulate mineral deportment issues, which you can't do in a basic batch mill except by doing locked cycle test, which ...
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Started by
Which power model is the most efficient to predict the correct power consumption in sag mill with change in process variables?I have developed a few dynamic simulators for different mineral/metal processing plants. Prediction of correct sag mill powe...
Last commented on by David
Do you have a grizzly ahead of you jaw crusher? What openning? Are you able to post a few photos of your working crusher? Ore pocket? Working crusher cavity? What about your coarse ore stockpile; d...
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Started by Maya Rothman
Last commented on by David
Example signature plot https://www.911metallurgist.com/blog/ultrafine-grinding-test-report-isamill-signature-plot
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Started by
Is the JK rock hardness method specifically A*b patented?Actually I want to know if I am able to define it myself and report it in a paper or not.
Last replied to by
From a legal perspective, the JK Drop Weight machine, test and the associated results analysis to generate A and b parameters are not patent protected so there is nothing to stop you doing your own te...
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Started by Victor Bergman
How can a trommel be effectively used?
Last replied to by
The trommel screen is like a micron screen, it remove large objects (oversize, bushes, plants, rocks) from feed from the mine to avoid choked feed pipes and or plant instability, and the (undersize/mi...
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Started by
For secondary grinding (Ball Mill), what discharge Configuration is ideal with regards to cost saving for atypical copper milling plant with a throughput of say 331dmt/h. Qualify the selection of your recommendation.
Last replied to by
The SAG mill is in open circuit. The only classification is by a double deck vibro screen with screen aperture of 10X10mm on top deck and 6X6mm on the bottom deck.
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Started by
Hello: I would like to start a new discussion. When HPGR should be used instead of SAGs in a grinding circuit. What are the technical advantages, sensitivity to feed distribution, hardness of ore, efficiency etc? What are the trade-offs between SAG v...
Last replied to by Unterstarm
Read:http://911Metallurgist.com/C/HPGR-SAG/Compare%20HPGR%20vs%20SAG%20USING%20THE%20SMC%20TEST-TO%20PREDICT%20COMMINUTION%20CIRCUIT%20PERFORMANCE.pdf http://911Metallurgist.com/C/HPGR-SAG/USE%20OF%20...
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Started by
We recently converted a grate discharge type ball mill (size 5.7X8.6m) to an Overflow type. Before conversion, the ball level was 26%, and we were able to obtain a grind of 90%+ passing 75mic at a throughput of 350t/h. After conversion it’s a night...
Last commented on by David
Thanks for this Johan
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Started by Standartenfurer
I’m looking for ideas to process the discarded material of a SAG mill. We have huge material stocks of this process that contains ore contaminated with metal balls and some scrap elements that makes it hard to process it on a crusher. I have seen a...
Last replied to by
You may find more information regarding the SAG discharge if you search them as "scats" (broken ball chips). Safety Notes; they result from internal stresses in the balls impact and heat energy in the...
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Started by
How to stop the leakage through seal ring and seal wiper in wet ball mill?
Last replied to by
Yes the mill is almost running with double its capacity (Rated 30TPH, running with 55 TPH), earlier we used to have Linatex seal wiper and SS seal ring. In this course Linatex seal wiper didn't give g...
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Started by Jean Rasczak
Auditing can be a key for continues improvement of mineral processing circuits specially grinding/comminution but every experts have their own way which might be achieved over the year by experience. It'll be perfect if everyone can make profit of t...
Last replied to by
I was recently informed by one of my friend about a new book about auditing a mineral processing plant. I hope to study it on google book.http://smemi.personifycloud.com/PersonifyEbusiness/Store/Produ...
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Started by
Interesting article link below, it gives a new approach on how to measure assets productivity. I think is more "real" than OEE. For commutation normally I would use a logic where OEE = (availability or run-time) * (Avg TPD/max TPD) * (recovery %). Th...
Last replied to by Jean Rasczak
Wrong metrics in my view. This thinking leads us along the mindless treadmill of more volumes and higher utilizations which are guaranteed to maximize (total) costs, even though they create an illusio...
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Started by
As a grinding media designer/supplier SGI considers that an MBT is not the best method for media selection.Do marked ball tests help determine if you have selected the best media for you mill?
Last replied to by
Yes, so much effort and expense to do this work - the cheap and easy part is the final data analysis. See page 101 of https://books.google.ca/books?id=sFhUPTaREnsC&lpg=PA103&ots=XC4BoEG8K2&dq=Marked...
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Started by Maya Rothman
Deseocalcular el consumo de bolas diarias para losmolinos de bolas y sag, tengo el consumo de kg de bolas /tmineral; el tonelaje de mineral a considerar para loscálculoses la cargafresca o la carga total que vamoler (esdecircargafresca + cargacircul...
Last replied to by
Tengounasimulación de nivel de llenado de bolas sag mill porsiteinteresa. Enambiente excel.
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Started by
The crop load of ball mill. It =ore + mill medium +water. But usually, it was used in a percentage formation. So how to calculate this percentage. I know this is really a basic question, but it puzzled me, for most books and papers just use it but no...
Last replied to by Paul Morrow
The ball charge and ore charge volume is a variable, subject to what is the target for that operation. The type of mill also is a factor as if it is an overflow mill (subject to the diameter of the di...
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Started by JohnnyD
The equation of the JKMRC breakage rate model published in papers is:T/hr α r.s.(1-a)There is no =How should I read and understand this rock breakage rate equation?
Last replied to by David
The 'equation' is a first-order rate relationship. The 'α' is a 'proportional to' symbol ( more correctly depicted as ∝)Throughput (T/hr) is proportional to r.s.(1-a) where, r = breakage rate, s = ...
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Started by
I need to be able effective have a solution of handling hard ore in my SAG mill circuit. Sometimes, facing the excessive hard ores in the SAG mill is a challenge for the plants. From the operational perspective, increasing mill speed or grinding medi...
Last replied to by
Spend some money at the front end with reducing the F80 by crusher, allow some of that hard competent rock to by-pass for SAG effect. Then reset the ball size and grade to balance the stream to match ...
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Started by Jean Rasczak
Does the choice of regrind mill and mill media affect downstream flotation performance? As it relates to http://www.sciencedirect.com/science/article/pii/S089268751400140XUntil recently little attention has been paid to the effect of size on flotatio...
Last replied to by
Why in the tails of the plant is 25% copper as chalcocite? And can be this copper flotation at low pH in the presence of xanthate? And flotation is carried in pachucs? If so, then:1. Apparently the ch...
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Started by
Am looking for the most or best Wear Resistant Mill Liners and manufacturers. Please could you advise what your recommendations for the best possible liners to use in an Iron Ore application and please share what %Mn was used including the % Cr if us...
Last replied to by
and if you are feeling rich http://www.magotteaux.com/
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Started by
Can people say that either they are happy that they selected sag mills or say they made wrong selection. In either case, if examples and a bit of information on ore type/top size/hardness of the ore/power consumption.
Last replied to by Zander Barcalow
This is good too http://is.gd/TJWe5O
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Started by Marshal Meru
Having used weight control and power draw to control Mill operations, using Mill Sound to run a mill was a new one for me. I found it unusual and not that effective.Has anyone else used that style of operation control to run their mill and did you fi...
Last replied to by
Mill Ears - that brings back memories. Love them. But my favourite was the initial work in South Africa with "Instrumented Liner Bolts" (Kloof Gold Mine SA, Mintek) measuring impact and conductivity (...
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Started by
How to define Quality of Grinding Media? Grinding media used in SAG Mills are subjected to strong abrasion and impact. They lose mass both in a continuous microscopic abrasive process and through discrete fracture of pieces that may range from a thin...
Last replied to by
Many of our customers write their own specification for ball chemistry and physical characteristics. Some also test every batch to ensure compliance with what specification is ordered. Getting what yo...
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Started by
Is the air core formation inside a hydrocyclone is needed or not? Got confused as many research papers suggest to minimize the air core diameter by several design modifications within the hydrocyclone. On the contrary air core is necessary to carry t...
Last replied to by
Some few fundamentals all know about cyclone.Air core:This will become Zerto in ropy underflow. In Ropy under flow few coarse particles which are supposed to come out from under flow, will try to esca...
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Started by
How do I size and design a mill for magnetite ore types with 75-250 t/h working? The ore consists of about 30% quartz and 30% magnetite and the amount of hematite is lesser than magnetite. The liberation of magnetite is interlocked with other mineral...
Last commented on by Zander Barcalow
Your production capacity seems to be low (max. 250 t/h). I do not know the required magnetite liberation size and weight recovery level. Based on the power consumption criteria, the best grinding flow...
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Started by Zander Barcalow
How much of an effect, if any, does rheology inside a SAG mill or any grinding mill? Does it have an effect on residence time?
Last replied to by
I have seen a ball mill circuit where a cyclone cluster (instead of a thickener) was employed for dewatering of the mill product stream upstream from gold leaching, and the cyclone overflow stream (i....
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Started by
Looking at dry grinding material of extreme hardness holding a BWi of 27kWh/t from an F80 of 6-8mm to a P80 of 16um in an air-swept compartmented ball mill. There are operating plants doing this to 75um, is 16um too fine? Only considering milling tec...
Last replied to by Zander Barcalow
If you expect to keep the dry process, as mentioned, the BM F80 is «coarse» under incidence of the required P80, and you are obliged to help the BMs. You can think to the HPRG equipment or study the...
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Started by
Please what is the best way of measuring the dosage of a semi-solid, solid, and liquid chemical grinding aid during wet grinding?Is it not possible to have a grinding aid (to be used for wet grinding of an ore) in solid form?My interest is on batch ...
Last replied to by Jean Rasczak
It's really about where the circuit operating conditions lie with respect on a curve of % solids - viscosity - grinding efficiency / cyclone efficiency. Truly the answer will be found through experime...
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Started by PERTHIAS
A SAG mill operates with a 10000 hp motor. Typical power draw is 80% of maximum. The 80% passing feed size to the mill is 5 inches and the mill discharge has an 80% passing size of 2.1mm. How do i calculate the Operating Work Index for this mil...
Last replied to by David
Try this SAG Mill Operating Work Index Calculator http://www.911metallurgist.com/blog/formula-to-calculate-a-mill-operating-work-index-equationIt looks like 6.6 kWh/ton
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Started by Maya Rothman
Electricity is one of the industry’s main cost drivers: higher energy costs will force closure of mine shafts.The key is to improve energy productivity, regardless of the source, starting with best practice operations. CEEC is supporting the global...
Last replied to by
A very accurate assessment. The driving force will be the cost of energy.
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Started by
If crop load =ore + grinding mill media +waterBut usually, it was used in a percentage formation. So how to calculate this percentage.I hear that generally 40% of mill volume is used by media and 60% of it (media volume) is solid , 40% is void.I ...
Last replied to by
I have to disagree with you... it is not "cast in concrete".Depends on the ore and mill type and for what goal or purpose.. What if it is a dry milling operation? Sag mills in the gold and copper ope...
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Started by Bob Mathias
What will be the better option in a Ball Mill Grinding Circuit: Screening or Cycloning?The separation is 500 micron and the feed is 100 TPH
Last replied to by
Yes the capacities need to be considered, but also the percent solids being feed to the system. With recent trends being to feed cyclones at high solids, there separating efficency is decreased, As t...

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