Model:Raw Bond/Barratt SAB & SABC Model - Revision history

Alex Doll at 18:36, 6 March 2022

2022-03-06T18:36:29Z

Alex Doll: /* Discussion */

2018-06-19T18:40:08Z

Discussion

Alex Doll: Alex Doll moved page Model:RawBondModel to Model:Raw Bond/Barratt SAB & SABC Model

2015-04-26T17:35:29Z

Alex Doll moved page Model:RawBondModel to Model:Raw Bond/Barratt SAB & SABC Model

Alex Doll: /* Recommended Usage */

2014-06-25T15:47:26Z

Recommended Usage

Alex Doll: /* Recommended Usage */

2014-05-01T16:20:50Z

Recommended Usage

Alex Doll: /* Discussion */

2014-05-01T16:15:45Z

Discussion

Alex Doll: /* Recommended Usage */

2014-04-08T11:37:32Z

Recommended Usage

Alex Doll: /* Raw Bond Model */

2014-03-05T17:18:31Z

Raw Bond Model

Alex Doll: /* Raw Bond Model */

2013-12-29T19:02:38Z

Raw Bond Model

Alex Doll: /* Raw Bond Model */

2013-03-05T01:29:27Z

Raw Bond Model

@@ Line 2: / Line 2: @@
 [[category:Specific Energy Models]]
 [[Category: Bond/Barratt Model]]
 == Raw Bond Model ==
 This is a SAG or AG mill plus ball mill model that estimates the specific energy consumption (E<sub>SAG</sub>) using the 1979 Barratt equation and the classical Bond work index equation including Rowland efficiency factors.  The model allows a manual calibration factor on both equations (''CF<sub>SAG</sub>'' and ''CF<sub>ball</sub>'', respectively).

← Older revision		Revision as of 18:40, 19 June 2018
Line 39:		Line 39:

	The ball mill oversize feed factor (EF<sub>4</sub><sup>BM</sup>) is always calculated with the ball mill work index. The optimal feed size for the EF<sub>4</sub><sup>BM</sup> is always calculated using the rod mill work index.		The ball mill oversize feed factor (EF<sub>4</sub><sup>BM</sup>) is always calculated with the ball mill work index. The optimal feed size for the EF<sub>4</sub><sup>BM</sup> is always calculated using the rod mill work index.
		+
		+	The '''Easag RM''' value in the circuit configuration is used to specify which work index to use for a particular size (RM above this size or BM below it). The RM and BM work index values are frequently pretty similar, so the model won't be very sensitive to this configuration setting. If you have an ore with a large difference in RM and BM work index values, then you should pay close attention to which size this transition in hardness seems to manifest. The size where the shift occurs is where you specify the '''Easag RM''' value. A transition is sometimes observable in the particle size distributions of the feed and product material from the RM and BM tests – is there a "kink" in the size distribution in both the RM product and BM feed PSDs?

	== Recommended Usage ==		== Recommended Usage ==

@@ Line 50: / Line 50: @@
 Because this model does not include an internal [[phantom cyclone]] mechanism, it is customary to include an allowance for it in the Ball Mill contingency factor (in the circuit settings) by using a value of 0.95 (some fines in SAG product) to 0.85 (many fines in SAG product).  If a SAG product does not include extra fines versus a [[standard size distribution]], then use a value of 1.00 (typical of very hard Western Australian ores).
-Because this model does not include an energy efficiency benefit due to pebble crushing, it may be necessary to apply a SAG contingency (in the circuit settings) value of less than one, for example: 0.95  would be a 5% energy benefit.  The Minnovex CEET1 model uses a factor of this type.  In their system, SAG Contingency would be 1.00 for no pebble crushing, 0.95 for pebble crushing.
+Because this model does not include an energy efficiency benefit due to pebble crushing, it may be necessary to apply a SAG contingency (in the circuit settings) value of less than one, for example: 0.95  would be a 5% energy benefit.  The Minnovex CEET1 model and the Amnipro SGI model use a factor of this type.  In their systems, SAG Contingency would be 1.00 for no pebble crushing, 0.85 for pebble crushing.
 == Default parameter values ==

@@ Line 48: / Line 48: @@
 [[file:WorkIndex-CompentIncompetent.png|alt=Diagram of work index by size|Work index by size examples of competent and incompetent ores]]
-Because this model does not include an internal [[phantom cyclone]] mechanism, it is customary to include an allowance for it in the CF<sub>ball</sub> factor by using a value of 0.95 (some fines in SAG product) to 0.85 (many fines in SAG product).  If a SAG product does not include extra fines versus a [[standard size distribution]], then use a value of 1.00.
+Because this model does not include an internal [[phantom cyclone]] mechanism, it is customary to include an allowance for it in the Ball Mill contingency factor (in the circuit settings) by using a value of 0.95 (some fines in SAG product) to 0.85 (many fines in SAG product).  If a SAG product does not include extra fines versus a [[standard size distribution]], then use a value of 1.00 (typical of very hard Western Australian ores).
 == Default parameter values ==

← Older revision		Revision as of 16:15, 1 May 2014
Line 25:		Line 25:

	<math> E_{total} = E_{SAG} + E_{ball} </math>		<math> E_{total} = E_{SAG} + E_{ball} </math>
		+
		+	===Pebble Crushing===
		+	The pebble crusher is considered part of the SAG mill for the purposes of this model. The displayed E<sub>peb</sub> value will always be zero, but the displayed E<sub>asag</sub> will include the shell power of the SAG mill plus the usable power of the pebble crusher.
		+
		+	Unlike other models, there is no explicit benefit to E<sub>total</sub> efficiency due to pebble crushing. This is a conservative assertion and is different from other models where inclusion of pebble crushing causes an immediate improvement in circuit energy efficiency.

	===Discussion===		===Discussion===

@@ Line 37: / Line 37: @@
 == Recommended Usage ==
-This model should be the upper end-member of the range of Bond/Barratt style models.  It is useful when interpreting pilot plant results to determine where the pilot plant results fall relative to the spectrum of models.  It can also be used as an extra-conservative model for design work.
+This model should be the upper end-member of the range of Bond/Barratt style models.  It is useful when interpreting pilot plant results to determine where the pilot plant results fall relative to the spectrum of models.  It can also be used as a conservative model for design work.
 Because this model does not include an internal [[phantom cyclone]] mechanism, it is customary to include an allowance for it in the CF<sub>ball</sub> factor by using a value of 0.95 (some fines in SAG product) to 0.85 (many fines in SAG product).  If a SAG product does not include extra fines versus a [[standard size distribution]], then use a value of 1.00.

@@ Line 7: / Line 7: @@
 This formula usually gives higher total circuit specific energy consumption estimates than the other Bond/Barratt models.  This is largely due to the absence of a [[phantom cyclone]] effect in the equations.
 <math>
 E_{SAG} = \left [ \left (
@@ Line 20: / Line 26: @@
 <math> E_{total} = E_{SAG} +  E_{ball} </math>
 As with most models, the power split between the SAG and ball mills is evaluated and the transfer size (T<sub>80</sub>) necessary to balance the power draw between the two stages is estimated.  If that transfer size is within the specified limits, then the calculation proceeds to calculate the E<sub>SAG</sub> and E<sub>ball</sub> using that transfer size.  If the transfer size to balance the power is outside the specified limits, then the transfer size size is forced to the limit and the E<sub>SAG</sub> and E<sub>ball</sub> values are then recalculated.  SAG-limited circuits (where the T<sub>80</sub> hits the upper limit) will result in the ball mill over-grinding unless (in the case of a variable speed mill) the ball mill speed is reduced to control the grind size.  Ball-limited circuits (where the T<sub>80</sub> hits the lower limit) will result in the charge level in the SAG mill dropping until its power draw matches the throughput limit dictated by the ball mill.  It is important to realize that once the SAG mill charge level drops below the ball charge, it can no longer empty and the mill power draw will be incalculable and an error message will appear.

@@ Line 14: / Line 14: @@
 <math> E_{total} = E_{SAG} +  E_{ball} </math>
-As with most models, the power split between the SAG and ball mills is evaluated and the transfer size (T<sub>80</sub>) necessary to balance the power draw between the two stages is estimated.  If that transfer size is within the specified limits, then the calculation proceeds to calculate the E<sub>SAG</sub> and E<sub>ball</sub> using that transfer size.  If the transfer size to balance the power is outside the specified limits, then the transfer size size is forced to the limit and the E<sub>SAG</sub> and E<sub>ball</sub> values are then calculated.  SAG-limited circuits (where the T<sub>80</sub> hits the upper limit) will result in the ball mill over-grinding unless (in the case of a variable speed mill) the ball mill speed is reduced to control the grind size.  Ball-limited circuits (where the T<sub>80</sub> hits the lower limit) will result in the charge level in the SAG mill dropping until its power draw matches the throughput limit dictated by the ball mill.  It is important to realize that once the SAG mill charge level drops below
+As with most models, the power split between the SAG and ball mills is evaluated and the transfer size (T<sub>80</sub>) necessary to balance the power draw between the two stages is estimated.  If that transfer size is within the specified limits, then the calculation proceeds to calculate the E<sub>SAG</sub> and E<sub>ball</sub> using that transfer size.  If the transfer size to balance the power is outside the specified limits, then the transfer size size is forced to the limit and the E<sub>SAG</sub> and E<sub>ball</sub> values are then recalculated.  SAG-limited circuits (where the T<sub>80</sub> hits the upper limit) will result in the ball mill over-grinding unless (in the case of a variable speed mill) the ball mill speed is reduced to control the grind size.  Ball-limited circuits (where the T<sub>80</sub> hits the lower limit) will result in the charge level in the SAG mill dropping until its power draw matches the throughput limit dictated by the ball mill.  It is important to realize that once the SAG mill charge level drops below the ball charge, it can no longer empty and the mill power draw will be incalculable and an error message will appear.
 Circuits that operate at or near the transfer size limits should be less efficient than the default formulas will estimate.  If you have a design that is consistently operating around the limits, then consider adding a contingency to inflate the specific energy consumption estimates to account for this poor grinding efficiency.  Alternatively, if you are designing a new circuit then choose a different combination of SAG and ball mills that operates in a more reasonable transfer size range.
-The rod mill oversize feed factor (EF<sub>4</sub><sup>RM</sup>) in the Barratt E<sub>SAG</sub> equation is calculated using the greater of the sample's rod mill or crushing work index.  The optimal feed size and EF<sub>4</sub> are both calculated using whichever is greater.  The ball mill oversize feed factor (EF<sub>4</sub><sup>BM</sup>) is always calculated with the ball mill work index.
+The rod mill oversize feed factor (EF<sub>4</sub><sup>RM</sup>) in the Barratt E<sub>SAG</sub> equation is calculated using the greater of the sample's rod mill or crushing work index.  The optimal feed size and EF<sub>4</sub> are both calculated using whichever is greater.
 == Recommended Usage ==