SAGMILLING.COM - Recent changes [en]

Software change log

Alex Doll — Fri, 29 May 2026 12:15:01 GMT

Change Log

← Older revision		Revision as of 12:15, 29 May 2026
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	==Change Log==		==Change Log==

			=== 2026-05-19: MAJOR UPDATE, significant upgrades to the platform ===
			* replaced the PHPlot library for generating plots with a python bridge
			* clicktoy libraries modernised
			* added grind curve to available mill detail tabs
			* moved the template creation button to the mill detail 'settings' tab
			* heat map added to twcompare
			* allow different visualisations of twcompare (used to only allow 'by lab')
			* cumulative plots of testwork available from buttons on Testwork Summary page
			* importing of testwork templates now compatible with exports from Testwork Summary page (including localisations in español and français)
			* flowsheet page now allows switching of the sample being viewed via clicking the sample name which triggers a drop-down with all available samples.

	=== 2025-08-26: Formatting change on some subscripts ===		=== 2025-08-26: Formatting change on some subscripts ===

Testwork: Bond ball mill work index

Alex Doll — Mon, 25 May 2026 20:49:30 GMT

Corrections and adjustments

Pebble crushing or not

Alex Doll — Mon, 25 May 2026 20:45:33 GMT

Created page with "== Pebble Crushing, or not == The choice of adding a pebble crusher to a circuit requires balancing the following: * the ratio of rod mill to ball mill work index values * the desired transfer size of the grinding circuit (what is the model running at) * energy efficiency of the grinding circuit === Ratio of work indices === If the rod mill (and crushing work index, to a lesser extent) are higher than the ball mill work index, then the circuit will probably require peb..."

New page

== Pebble Crushing, or not ==

The choice of adding a pebble crusher to a circuit requires balancing the following:
* the ratio of rod mill to ball mill work index values
* the desired transfer size of the grinding circuit (what is the model running at)
* energy efficiency of the grinding circuit

=== Ratio of work indices ===
If the rod mill (and crushing work index, to a lesser extent) are higher than the ball mill work index, then the circuit will probably require pebble crushing to operate efficiently.
[[File:PebbleZones_WiRM-WiBM.png]]

=== Desired transfer sizes ===
The transfer sizes displayed by the software are an instruction, and not a prediction. You, the designer, must design a circuit that is capable of achieving the transfer sizes in order for the circuit to operate efficiently.
Pebble crushing causes the transfer size in operating plants to coarsen. This means:
* Use a pebble crusher if the model is displaying transfer sizes at the coarse end of the range in the [[Modelling: Transfer size limits|transfer size]] rules of thumb.
* Do not use a pebble crusher if the model is displaying transfer sizes at the fine end of the range in the rules of thumb.

=== Circuit efficiency ===
Most specific energy models predict the overall circuit efficiency (the E_total) is about 5% better with pebble crushing (SABC) versus without (SAB). If the energy consumption is a design priority, then include pebble crushing.

== Pebble recycle rate ==
The software doesn't predict the recycle rate of pebbles, it only predicts the power draw of the black box consisting of the SAG mill and pebble crushers combined. To get an accurate prediction of the pebble flow rate requires using population balance models (such as JK SimMet), but here are some rules of thumb for power based models:

Start with a 15-20% circulating load and adjust as follows:
* If the WiC is less than WiRM, and WiRM is less than the WiBM, then the pebble flow will be low. This is because the rock breakage will "quickly speed through" the rod mill size range (aka, pebble size range) and breakage gets more difficult when particles get to the ball mill size range.
* If your target transfer size is fine, then more pebbles will be recirculating to the SAG until the particles get to the transfer size range.
* SAB circuits usually have lower transfer sizes and lower pebble flow rates than SABC circuits due to the grate configuration in the SAG mill, but run the risk of "choking" on pebbles if the pebble recirculation rate is too low. Power-based models can't see this condition, so always recommend some extra grate panels with pebble ports be in the warehouse, just in case.

HPGR or SAG

Alex Doll — Mon, 25 May 2026 20:42:06 GMT

Created page with "== HPGR or SAG? == Choosing an appropriate grinding configuration is important for conceptual design. Here are some things to consider when making the choice between an HPGR-ball mill circuit and a SAG-ball mill circuit. ===Work index ratios === Having a hard ore is not a valid reason for choosing an HPGR circuit, the ore must be hard in a certain way. More specifically, it should have a rod mill work index greater than the ball mill work index, and a ball mill work i..."

New page

== HPGR or SAG? ==
Choosing an appropriate grinding configuration is important for conceptual design. Here are some things to consider when making the choice between an HPGR-ball mill circuit and a SAG-ball mill circuit.

===Work index ratios ===
Having a hard ore is not a valid reason for choosing an HPGR circuit, the ore must be hard in a certain way. More specifically, it should have a rod mill work index greater than the ball mill work index, and a ball mill work index below 20 metric units:

[[File:WiSignature_HPGR.png]]

A SAG-amenable ore has the opposite orientation, the rod mill work index should be equal to, or less than the ball mill work index. Ajax is a British Columbia copper porphyry with a strong signal that it would make an efficient SAG circuit.

[[File:WiSignature_Ajax.png]]

A low crushing work index is helpful for SAB and SABC circuits, as in the Ajax example.

A project where the rod mill and ball mill work index values are similar, and where both are high can go either way. Example of this are Mt Milligan (SAG plant) and Tropicana (HPGR plant) where local conditions (E.g. price of power, climate) make the choice based on a financial evaluation.

[[File:WiSignature-MtMilligan.png]]

=== Effect on the ball mill ===
HPGR and SAG mills are used to make feed for a ball mill. The HPGR usually has a coarser transfer size than a SAG, meaning it puts more load on the ball mill. The SAG mill's "phantom cyclone" effect is usually greater than the "microcracking" effect in an HPGR until you get to really hard material where both of these effects turn negative (industrial ball mill operating work index is greater than the laboratory ball mill work index).

If the ball mill work index is significantly higher than the rod mill work index (like the Ajax example, above), then HPGR is a poor choice.

Main Page

Alex Doll — Mon, 25 May 2026 20:41:39 GMT

Operating the Software

← Older revision		Revision as of 20:41, 25 May 2026
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	* [[How to design a new circuit]] using grindability testing		* [[How to design a new circuit]] using grindability testing
	* [[How to make temporary changes]] to models or grindability test data and without saving		* [[How to make temporary changes]] to models or grindability test data and without saving
	* Design choices: [[HPGR or SAG?]]		* Design choices: [[HPGR or SAG]]?
	* Design choices: [[Pebble crushing or not?]]		* Design choices: [[Pebble crushing or not]]?
	* Design implications of [[Modelling: Transfer size limits\|Transfer Size]]		* Design implications of [[Modelling: Transfer size limits\|Transfer Size]]

Model:Bond HPGR and ball mill

Alex Doll — Mon, 25 May 2026 20:14:51 GMT

Formulae

← Older revision		Revision as of 20:14, 25 May 2026
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	The ball mill specific power consumption E<sub>ball</sub> is determined by deducting a cone crushing component from the Bond/Rowland E<sub>ssbm</sub> specific power consumption. See the base formulae in the [[Model:BondSSBMModel\|Bond SSBM model]].		The ball mill specific power consumption E<sub>ball</sub> is determined by deducting a cone crushing component from the Bond/Rowland E<sub>ssbm</sub> specific power consumption. See the base formulae in the [[Model:BondSSBMModel\|Bond SSBM model]].

	<math> E_{ball} = E_{ssbm} \times (1+CF) - Wi_{C} \times \left ( \tfrac {10}{\sqrt{ 9400 }} - \tfrac {10}{\sqrt{ T_{80} }} \right ) </math>		<math> E_{ball} = E_{ssbm} \times (1+CF) - Wi_{C} \times \left( \tfrac{10}{\sqrt{ 9400 }} - \tfrac{10}{\sqrt{ T_{80} }} \right) </math>

	where ''CF'' is the '''Essbm calibration factor''' (in the Circuit Settings) for ball mill operating work index versus laboratory ball mill work index. A value of zero means use the Bond/Rowland SSBM formula to predict E<sub>ball</sub>, a value of '''-0.05''' means use 5% less than Bond/Rowland SSBM formula to predict E<sub>ball</sub>. ''CF'' is a negative number if Wi<sub>O</sub> is less than the laboratory work index.		where ''CF'' is the '''Essbm calibration factor''' (in the Circuit Settings) for ball mill operating work index versus laboratory ball mill work index. A value of zero means use the Bond/Rowland SSBM formula to predict E<sub>ball</sub>, a value of '''-0.05''' means use 5% less than Bond/Rowland SSBM formula to predict E<sub>ball</sub>. ''CF'' is a negative number if Wi<sub>O</sub> is less than the laboratory work index.

User:Alex Doll

Alex Doll — Sun, 17 May 2026 13:19:40 GMT

Test suite before deploying new code

← Older revision		Revision as of 13:19, 17 May 2026
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	On the development server		On the development server
	# create a new project		# create a new project
	## add a ~~user~~ to this new project		## add a member to this new project
	# create a new test result		# create a new test result
	## Add the 3 work index values		## Add the 3 work index values

Conversions between test types

Alex Doll — Fri, 15 May 2026 13:20:16 GMT

Medium size class

← Older revision		Revision as of 13:20, 15 May 2026
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	\|-		\|-
	\| '''Bond rod mill work index versus SGI & SPI''' <br> Only considering rod mill work index tests performed in laboratory mills equipped with wave liners. SGI does not contain a density correction, and this relationship is probably only valid for ore density in the range of 2.50 to 2.80 t/m<sup>3</sup> <br><br>Only considers SGI values less than 150 as greater values are meaningless.		\| '''Bond rod mill work index versus SGI & SPI''' <br> Only considering rod mill work index tests performed in laboratory mills equipped with wave liners. SGI does not contain a density correction, and this relationship is probably only valid for ore density in the range of 2.50 to 2.80 t/m<sup>3</sup> <br><br>Only considers SGI values less than 150 as greater values are meaningless.
	\|\| [[File:~~ExampleDB-WiRMvSGI-comparison~~.~~png~~]]		\|\| [[File:WiRM_v_SGI.svg]]
	\|-		\|-
	\| '''SGI & SPI versus Bond rod mill work index''' <br> Only considering rod mill work index tests performed in laboratory mills equipped with wave liners. SGI does not contain a density correction, and this relationship is probably only valid for ore density in the range of 2.50 to 2.80 t/m<sup>3</sup> <br><br>Only considers SGI values less than 150 as greater values are meaningless.		\| '''SGI & SPI versus Bond rod mill work index''' <br> Only considering rod mill work index tests performed in laboratory mills equipped with wave liners. SGI does not contain a density correction, and this relationship is probably only valid for ore density in the range of 2.50 to 2.80 t/m<sup>3</sup> <br><br>Only considers SGI values less than 150 as greater values are meaningless.
	\|\| [[File:~~ExampleDB-WiRMvSGI-comparison~~.~~png~~]]		\|\| [[File:SGI_v_WiRM.svg]]
	\|-		\|-
	\| '''SGI & SPI''' versus '''A×b'''<br> Only considering SGI values below 150 minutes. SGI does not contain a density correction, and this relationship is probably only valid for ore density in the range of 2.50 to 2.80 t/m<sup>3</sup>		\| '''SGI & SPI''' versus '''A×b'''<br> Only considering SGI values below 150 minutes. SGI does not contain a density correction, and this relationship is probably only valid for ore density in the range of 2.50 to 2.80 t/m<sup>3</sup>

File:SGI v WiRM.svg

Alex Doll — Fri, 15 May 2026 13:18:27 GMT

Alex Doll uploaded File:SGI v WiRM.svg Public Grindability Database regression of the SAG Grindability Index versus the Bond-type rod mill work index. Only considers SGI values below 150 minutes.

New page

== Summary ==
Public Grindability Database regression of the SAG Grindability Index versus the Bond-type rod mill work index. Only considers SGI values below 150 minutes.

File:WiRM v SGI.svg

Alex Doll — Fri, 15 May 2026 13:17:09 GMT

Alex Doll uploaded File:WiRM v SGI.svg Public Grindability Database regression between Bond-type rod mill work index and the SAG Grindability Index (SGI), only considering SGI values below 150 minutes.

New page

== Summary ==
Public Grindability Database regression between Bond-type rod mill work index and the SAG Grindability Index (SGI), only considering SGI values below 150 minutes.

File:ExampleDB-WiRMvSGI-comparison.png

Alex Doll — Fri, 15 May 2026 13:12:36 GMT

Alex Doll reverted File:ExampleDB-WiRMvSGI-comparison.png to an old version Reverted to version as of 13:59, 2 July 2024 (UTC)

New page

Example database comparison of Bond rod mill work index (wave-liner machines) against the SAG grindability index or SAG Power Index (SGI or SPI™).

File:ExampleDB-WiRMvSGI-comparison.png

Alex Doll — Fri, 15 May 2026 13:11:17 GMT

Alex Doll uploaded a new version of File:ExampleDB-WiRMvSGI-comparison.png

New page

Example database comparison of Bond rod mill work index (wave-liner machines) against the SAG grindability index or SAG Power Index (SGI or SPI™).

Conversions between test types

Alex Doll — Fri, 15 May 2026 13:10:25 GMT

Medium size class

← Older revision		Revision as of 13:10, 15 May 2026
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	\|\| [[File:ExampleDB-WiRMvSGI-comparison.png]]		\|\| [[File:ExampleDB-WiRMvSGI-comparison.png]]
	\|-		\|-
	\| '''Bond rod mill work index ~~versus SGI & SPI~~''' <br> Only considering rod mill work index tests performed in laboratory mills equipped with wave liners. SGI does not contain a density correction, and this relationship is probably only valid for ore density in the range of 2.50 to 2.80 t/m<sup>3</sup> <br><br>Only considers SGI values less than 150 as greater values are meaningless.		\| '''SGI & SPI versus Bond rod mill work index''' <br> Only considering rod mill work index tests performed in laboratory mills equipped with wave liners. SGI does not contain a density correction, and this relationship is probably only valid for ore density in the range of 2.50 to 2.80 t/m<sup>3</sup> <br><br>Only considers SGI values less than 150 as greater values are meaningless.
	\|\| [[File:ExampleDB-WiRMvSGI-comparison.png]]		\|\| [[File:ExampleDB-WiRMvSGI-comparison.png]]
	\|-		\|-

← Older revision		Revision as of 20:49, 25 May 2026
(2 intermediate revisions by the same user not shown)
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	The computation of a Bond ball mill work index was empirically calibrated by Fred Bond using a short ton basis. The modern (metric tonne) basis is the following equation:		The computation of a Bond ball mill work index was empirically calibrated by Fred Bond using a short ton basis. The modern (metric tonne) basis is the following equation:

	Wi_{BM} = \frac{1.1023 \times 44.5}{P_{100}^{0.23} \times gpr^{0.82} \times (\frac{10}{\sqrt{P_{80}}} - \frac{10}{\sqrt{F_{80}}})}		<math> Wi_{BM} = \frac{1.1023 \times 44.5}{P_{100}^{0.23} \times gpr^{0.82} \times (\frac{10}{\sqrt{P_{80}}} - \frac{10}{\sqrt{F_{80}}})}</math>

	===Derived values composed from Wi<sub>BM</sub> results===		===Derived values composed from Wi<sub>BM</sub> results===
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	** Units are kWh/t based on Morrell's empirical calibration.		** Units are kWh/t based on Morrell's empirical calibration.
	** This value is used in the [[:Category:SMC Model\|Morrell Mi models]].		** This value is used in the [[:Category:SMC Model\|Morrell Mi models]].
	** \Mib = \frac{18.18}{P_{100}^{0.295} × (gpr) \left [ P_{80}^{f(P_{80})} - F_{80}^{f(F_{80})} \right ]} kWh/t		** <math> Mib = \frac{18.18}{P_{100}^{0.295} \times (gpr) \left [ P_{80}^{f(P_{80})} - F_{80}^{f(F_{80})} \right ]}</math> kWh/t
	** where: f(''x'') = -0.293 - ''x''/10⁶		** where: f(''x'') = -0.293 - ''x''/10⁶
	* ''Levin B'' parameter is calculated for a sample if the following are available: '''umClosing''', '''F80''', '''P80''', '''gpr''', '''fdpassing'''.		* ''Levin B'' parameter is calculated for a sample if the following are available: '''umClosing''', '''F80''', '''P80''', '''gpr''', '''fdpassing'''.
	** Units of the Levin B are mWh per revolution of a standard Bond grindability ball mill (mWh/rev). Watch out, as this metric is also given as kWh/rev in literature.		** Units of the Levin B are mWh per revolution of a standard Bond grindability ball mill (mWh/rev). Watch out, as this metric is also given as kWh/rev in literature.
	** This value is not used in any computations, but can be used in external calculation such as [https://sagmilling.com/articles/37/view/2020%20CMP%20-%20Alex%20Doll.pdf?s=1 Functional Performance].		** This value is not used in any computations, but can be used in external calculation such as [https://sagmilling.com/articles/37/view/2020%20CMP%20-%20Alex%20Doll.pdf?s=1 Functional Performance].
	** B = \frac{4900 × (gpr)^{0.18}}{P_{100}^{0.23} (100 - Fd%passing)} mWh/rev		** <math> B = \frac{4900 \times (gpr)^{0.18}}{P_{100}^{0.23} (100 - Fd%passing)} </math> mWh/rev

	=== Modelling ===		=== Modelling ===
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	The grams per revolution can be computed by rearranging Bond's laboratory equation:		The grams per revolution can be computed by rearranging Bond's laboratory equation:

	gpr = \left[ \frac{1.1023 \times 44.5}{P_{100}^{0.23} \times Wi_{BM} \times (\frac{10}{\sqrt{P_{80}}} - \frac{10}{\sqrt{F_{80}}})} \right]^\frac{1}{0.82}		<math> gpr = \left[ \frac{1.1023 \times 44.5}{P_{100}^{0.23} \times Wi_{BM} \times (\frac{10}{\sqrt{P_{80}}} - \frac{10}{\sqrt{F_{80}}})} \right]^\frac{1}{0.82} </math>


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	'''Correct for 'non standard' feed size'''		'''Correct for 'non standard' feed size'''

	If the ball mill test feed material was too small for the stage crushing to make a normal ~~F80~~, then the correction from ''Nikolić, Doll, & Trumić (2022)'' [[https://www.researchgate.net/publication/363350623_A_new_methodology_to_obtain_a_corrected_Bond_ball_mill_work_index_valid_with_non-standard_feed_size A new methodology to obtain a corrected Bond ball mill work index valid with non-standard feed size]] may be applied. The method is also described in Procemin 2022 paper [[https://www.researchgate.net/publication/372393426_Secrets_of_the_Bond_Ball_mill_grindability_test Secrets of the Bond Ball Mill Grindability Test]]		If the ball mill test feed material was too small for the stage crushing to make a normal F<sub>80</sub>, then the correction from ''Nikolić, Doll, & Trumić (2022)'' [[https://www.researchgate.net/publication/363350623_A_new_methodology_to_obtain_a_corrected_Bond_ball_mill_work_index_valid_with_non-standard_feed_size A new methodology to obtain a corrected Bond ball mill work index valid with non-standard feed size]] may be applied. The method is also described in Procemin 2022 paper [[https://www.researchgate.net/publication/372393426_Secrets_of_the_Bond_Ball_mill_grindability_test Secrets of the Bond Ball Mill Grindability Test]]

	=== Computing Mib from incomplete Ball Mill Work Index data ===		=== Computing Mib from incomplete Ball Mill Work Index data ===