Crusher2
Navigation: Main Page > Models > Size Distribution Models
Contents
 1 General Description
 2 Modelling Crushing and Comminution
 3 Inputs and Outputs
 4 Model Theory  Fixed Partition Method
 5 Model Theory  Whiten Crusher Method
 6 Model Theory  Selection/Breakage Method
 7 Data Sections
 8 Adding this Model to a Project
General Description
This model implements predictive comminution with a number of open literature correlations. The model can handle multiple ore streams with different selection and breakage functions and includes optional internal classification to model various closed circuit configurations.
 Partition Curves
 Whiten Crusher Model
 Selection/Breakage Models
 Test Data
The specific model is selected with the Method drop down list on the Crusher2 or Crusher tab.
Modelling Crushing and Comminution
If you are using these models you should be aware that getting useful results requires information about both the performance of the specific crusher type, and the mechanical properties of the ore. There are many different crusher and mill types, and each crusher type will perform differently for a given ore. At the same time, different ore characteristics will have a major impact on the performance of a specific crusher  the same unit may produce large quantities of fines with one ore and much coarser product with a different ore.
The recommended use for these models is to have existing data on the performance of a specific unit with a specific ore  and to tune the parameters of the model to match plant data. Changes in the ore flow or incoming size distribution should be modeled accurately. If a new ore has similar characteristics and mechanical testing is done to determine the new ore parameters, then the models should give a reasonable indication of how the new ore will behave in an existing plant.
Predictive crushing modelling is not an exact science and requires considerable background knowledge, as well as actual test data, to get useful results. The references below provide useful background information on modelling, as well as indicating the specific test data needed for the SysCAD model.
Diagram
The diagram shows the default drawing of the Crusher, with all of the streams that must be connected to the unit.
The physical location of the streams connecting to the Crusher is unimportant. The user may connect the streams to any position on the unit.
Inputs and Outputs
Label  Required Optional 
Input Output 
Number of Connections  Description  
Min  Max.  
Feed 
1 Required 
In 
1 
20 
The feed to the Crusher 
Product 
Required 
Out 
1 
1 
The product from the Crusher 
Model Theory  Fixed Partition Method
The user defines a fixed size distribution (partition) as the product from the Crusher.
The model will produce the user defined size distribution even if this would result in the crusher producing a coarser product than feed. This is best demonstrated using an example:
Size' Range' (mm) 
Feed Fraction (%) 
Required Discharge 
+10.00  20  15 
+1.70  10  15 
+0.85  15  20 
+0.50  15  10 
+0.10  20  10 
+0.01  15  10 
0.01  5  20 
(sum)  (100)  (100) 
In the above example, there is enough material in the +10.0mm and +1.7mm feed size ranges to meet the required discharge product size distribution. For the +0.85mm size range only 15% is available where 20% is requested.
Model Theory  Whiten Crusher Method
This is an empirical model incorporating breakage and classification, based on the key parameter [math]T_{10}[/math] for breakage, and parameters [math]K_1, K_2[/math] and K3 for classification.
The form of the Whiten classification function is:
[math] C(x) = 1\left(\frac{K_2x}{K_2K_1}\right)^{K_3}, \qquad K_1 \lt x \lt K_2 [/math]
Where the parameters K1, K2 and K3 can be entered directly or calculated from equipment variables and operating conditions.
The actual breakage function is determined as a spline fit to test data which is specified as well.
If the key parameters are calculated, the following correlations are used:
 K1 = A0 + A1*CSS  A2*TPH + A3*F80 + A4*LLEN
 K2 = B0 + B1*CSS + B2*TPH + B3*F80  B4*LHR + B5*ET
 T10 = D0  D1*CSS + D2*TPH  D3*F80
 where
 CSS = Closed Side Setting (mm)
 TPH = Throughput (dry t/h)
 F80 = 80% pass size of Feed (mm)
 LLEN = Liner Length (mm)
 LHR = Liner age (hours)
 ET = Eccentric Throw (mm)
 A0 to A4 are parameters for K1, obtained from data fitting.
 B0 to B5 are parameters for K2, obtained from data fitting.
 D0 to D3 are parameters for T10, obtained from data fitting.
Notes:
 These are linear offsets to base values which depend on the operating conditions and crusher configuration. See MCC for further discussion.
 The parameters A0, B0 correspond to base values of K1, K2
 The parameters A1, A2, A3, A4, B1.. B5 are hidden and by default set to zero. Unhide these fields if you need to adjust the K values based on operating conditions and crusher configuration.
 So K1=A0 and K2=B0 if other parameters are not set.
Ore Specific Breakage
The ore properties are given as a table (MCC Table 6.1, General appearance function for crusher model)
This data is determined by various ore tests. The default values are those from MCC.
A second table is provided for ore specific comminution energy, Ecs. This gives the size specific energy needed to achieve a particular degree of breakage.
Reference
NapierMunn et al "Mineral Comminution Circuits  Their Operation and Optimisation (MCC)", Chapter 6
Model Theory  Selection/Breakage Method
In the subsequent discussion we use the following notation, loosely following that of Taveres[1] for discrete bin PSD modelling.
The SysCAD PSD model is based on a user supplied sieve series, with sizes [math]D_0, \,D_1\dots D_N[/math] which form N bins, with bin k containing particles in the size range [math]D_{k1}\leq x \lt D_k[/math]. Each bin has a characteristic size [math]d_k[/math], which is typically the geometric mean of the upper and lower sizes, though this can be modified by a user supplied correction.
The new comminution model implements a number of open literature correlations for selection and breakage. The overall breakage function is composed of both a selection function (breakage probability) and a breakage distribution (fragment size distribution).
Breakage Probability Selection Functions
In the following equations [math]S_i[/math] is the probability that a particle in bin i breaks.
Vogel Selection Function
 [math]S_i = 1e^{f_{mat}d_i k(W_{m,kin}W_{m,min})}[/math]
 where:
 f_{Mat} = Material Parameter that characterises the resistance of particulate material against fracture in impact comminution.
 W_{m_kin} = Massspecific kinetic impact energy.
 W_{m_min} = Massspecific threshold energy for particle breakage, i.e. the specific energy which a particle can take up without fracture.
Note that in the SysCAD model, a size independent specific energy is specified, ie [math] x\times W_{m,min}[/math]
 k = Number of impact events.
Reference
VogelPeukert, Breakage Behaviour of Different Materials  Construction of a Mastercurve for Breakage Probability, Powder Technology, 2003.
Austin Selection Function
 [math]S_i = S_1(\frac{d_i}{d_1})^\alpha[/math]
 where:
 S_{1} = Material Parameter. 0 <= S_{1} <= 1
 [math]\alpha[/math] = Parameter. 0 <= [math]\alpha[/math] <= 1
 d_{1} = Minimum particle size. 0 <= d_{1} <= d_{max}
 d_{max} = Maximum particle size in the feed stream
Reference
Austin L.G. et al, A Rapid Computational Procedure For UnsteadyState Ball Mill Circuit Simulation, SMEAIME, 1984.
Breakage function for discrete bins
The Breakage function is actually a continuous function.
 The Reid and Stewart form (basically a double Schumann equation) is
 [math]B(X) = \Phi\left(\frac{X}{X_0}\right)^\gamma+(1\Phi)\left(\frac{X}{X_0}\right)^\beta[/math]
 This calculates the fraction of particles of size [math]X_0[/math] that will end up smaller than size X after breakage.
In the discrete form, we start with the following cumulative breakage curves.
Here [math]B_{ji}[/math] = Fraction of particles from a bin of characteristic size i breaking below size j
ReidStewart form (Perry)
 [math]B_{ji} = \Phi\left(\frac{D_j}{d_i}\right)^\gamma+(1\Phi)\left(\frac{D_{j}}{d_i}\right)^\beta[/math]
 where:
 [math]\Phi[/math] = Experimentally determined material parameter.
 [math]\gamma[/math] = Experimentally determined material parameter.
 [math]\beta[/math] = Experimentally determined material parameter.
Reference
Perry et al Perry's Chemical Engineers' Handbook 6^{th} or 7^{th} Edition, McGrawHill 1984.
Austin Breakage Function
 [math]B_{ji} = \Phi\left(\frac{D_j}{d_i}\right)^\gamma+(1\Phi)\left(\frac{D_{j+1}}{d_i}\right)^\beta[/math]
 where the parameters are the same as for the ReidSteward form above.
The Austin form allows for complete breakage of all selected particles in a bin since
[math]\frac{D_{j+1}}{d_j}\gt1[/math] will force the cumulative function to be greater than 1 (and thus set to 1 for breakage to the same bin).
Vogel Breakage Function
 [math]B_{ji} = \frac12\left(\frac {D_j}{d_i}\right)^q\left[1+\tanh\frac{D_jx'}{x'}\right][/math]
Tavares Breakage Function
 This implementation uses a single constant [math]t_{10}[/math] supplied as a parameter
 [math]B_{ji} = 1(1t_{10i}) ^{\left[\frac9{d_i/D_j1}\right]^\alpha}[/math]
 where
 [math]\alpha[/math] = Material Parameter based on experimental data.
 t_{10} = Material Parameter
Reference
Tavares Optimum Routes for Particle Breakage by Impact, Powder Technology 142, 2004.
Logarithmic form
 [math]B_{ji} = A\ln\frac{D_j}{d_i}+1[/math]
 where
 A = Material Parameter
User Weibull form
 [math]B_{ji} = 1\exp(\left(\frac{x  x_u}{x^*x_u}\right)^n)[/math]
 where
 [math]x = \frac{D_j}{d_i}[/math]
 n = User Parameter. n>0
 x_{u} = User Parameter
 x^{*} = User Parameter: x^{*} > x_{u}
Notes
 For all these distributions, the fractional breakage from bin i into bin j is then just the difference of the cumulative breakages between the upper size and lower size.
 The Reid, Taveres, Log and Weibull distributions are scale invariant and only depend on the ratio of mother to daughter particle size.
 The Vogel breakage distribution depends on the impact velocity
Multiple Impact Events
In some crushing operations, material is subject to multiple impact events. The parameter NStressEvents is used to model this.
With N multiple impact events, the results are identical to having N individual crusher units with the same parameters and one impact event:
Following the PSD distribution through the multiple events:
Fractional Impact Events
The number of stress events need not be an integer. It is possible to have 1.5 stress events, which would correspond to a situation where some of the feed undergoes two impacts.
The result of having two crushers with 2.5 impact events is the same as having five crushers with a single impact event or any other combination adding up to the same total:
Impact Velocity
The selection (and some of the breakage) models involve a velocity or specific energy which is user supplied.
 For an impact mill, this is just the impact velocity;
 For a hammer mill, it is calculated from rotation speed and diameter.
Classification
When internal classification is turned on, additional parameters are available for the classification function
With internal classification, particles of larger sized are retained in the mill; the overall internal flow of material can be represented as follows.
The model allows user entry for all the parameters (Selection, Breakage and Classification). If there are multiple ores, data is only displayed for a single ore, and the user can select which ore to display.
Using this representation, we can model other configurations. A simple closed circuit milling system has the following transfer function:
Data Sections
The default sections and variable names are described in detail in the following tables. The default Crusher access window consists of three sections. This number may increase or decrease, based on user configuration.
 Crusher2 tab  Contains general information relating to the unit.
 QFeed  Optional tab, only visible if ShowQFeed is enabled. This page shows the properties of the mixed stream as the feed to the Crusher2 model.
 Crusher tab will have different fields depending upon the Method selected by the user:
 Fixed Partition  The fields visible if the user selects the 'Fixed Partition' method.
 Whiten Crusher  The fields visible if the user selects the 'Whiten Crusher' method.
 Selection/Breakage  The fields visible if the user selects the 'Selection/Breakage' method.
 Test Data  The fields visible if the user selects the 'Test Data' method.
 Results  Only visible if Method is set to 'Whiten Crusher' and ShowResults is enabled.
 Selection/Breakage  Visible when method is set to Selection/Breakage.
 QProd  Optional tab, only visible if ShowQProd is selected. This page shows the properties of the final product stream from the Crusher2 model.
 Info tab  Contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
 Links tab, contains a summary table for all the input and output streams.
 Audit tab  Contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.
Crusher2 Page
Class: Crusher2
Symbol / Tag  Input/ Calc  Description 
Common First Data Section  
Requirements  
On  Check Box  This enables the unit. If this box is not checked, then the material will pass straight through the crusher with no change to the size distribution. 
Method  Fixed Partition  The user defines a discharge partition curve from the Crusher. This can be one size distribution for all solids or one for each solid which can have its own size distribution. 
Whiten Crusher  The product size distribution will be determined using the Whiten empirical model which incorporates breakage and classification, based on a number of parameters. Different parameters can be used for different solids.  
Selection/Breakage  The user defines the Selection and Breakage criteria for the crusher. Different methods are available and different parameters can be used for different solids.  
Test Data  The user defines a Feed and Product size distribution. This can be one set of size distributions for all solids or one set for each solid which can have its own size distribution. These distributions are normally obtained from test work.  
Power Calculation  
BondWorkIndex / BondWI  Input  The Bond Work Index of the rock. This number will be used to calculate the power required to produce the final product. 
Options  
ShowQFeed  Tick Box  QFeed and associated tab pages (eg Sp) will become visible, showing the properties of the combined feed stream. See Material Flow Section. 
ShowQProd  Tick Box  QProd and associated tab pages (eg Sp) will become visible, showing the properties of the products. See Material Flow Section. 
SizeForPassingFracCalc  Input (global)  Size fraction for % Passing calculation. The size fraction input here will be shown in the results section. 
FracForPassingSizeCalc  Input (global)  Fraction passing for Size calculation. The fraction input here will be shown in the results section. 
Intervals  Ascending  Toggle Button (Intervals_Ascending), the size distribution will be displayed with the largest sizes at the top of the list. 
Descending  Toggle Button (Intervals_decending) The size distribution will be displayed with the smallest sizes at the top of the list.  
Results  
Power  Calc  The calculated power to grind the product.

DistributionUsed  Result  The number of size distribution being used. If only one size distribution has been defined in the configuration file, then the distribution number used will be 0. The name of the distribution will be shown in brackets. 
Stream Result Summary The following fields are shown in a table for the Feed and Product streams.  
MassFlow / Qm  Calc  The mass flow rate of the Feed/Product streams. 
SolidMassFlow / SQm  Calc  The solid mass flow rate of the Feed/Product streams. 
LiquidMassFlow / LQm  Calc  The liquid mass flow rate of the Feed/Product streams. 
VolFlow / Qv  Calc  The volumetric flow rate of the Feed/Product streams. 
Temperature/ T  Calc  The temperature of the Feed/Product streams. 
Density / Rho  Calc  The density of the Feed/Product streams. 
SolidFrac / Sf  Calc  The solids fraction of the Feed/Product streams. 
LiquidFrac / Lf  Calc  The liquid fraction of the Feed/Product streams. 
Passing  Calc  Returns the % Passing of the user defined size (defined above) of the Feed/Product streams. 
Passes  Calc  Returns the size that has the user defined % Passing (defined above) of the Feed/Product streams. 
Crusher Page  Fixed Partition
The fields that will be visible when the Method selected is 'Fixed Partition'. See Model Theory  Fixed Partition Method for more information.
Tag / Symbol  Input / Calc  Description 
Requirements  
Method  Fixed Partition  The user defines a discharge partition curve from the Crusher. This can be one size distribution for all solids or one for each solid which can have its own size distribution. 
IndividualCurves  CheckBox  If this is ticked, then the user enters discharge partition curves for each individual solid with a partition curve. If the box is NOT ticked, then the user enters a single curve that is used for all of the solids. This is shown in the image below. 
Curves  Input  The user enters the required fraction of material in each size interval to match the required discharge partition curve(s). (see image below) 
Results  
SolidX(s).MassFlow / SolidX(s).Qm  Calc  The mass flow of the specified solid species. If it is the default solid species, then it will include the flow of any solids that were NOT specified to have an associated size distribution in the project cfg file. 
Crusher Page  Whiten Crusher
The fields that will be visible when the Method selected is 'Whiten Crusher'. See Model Theory  Whiten Crusher Method for more information.
Tag / Symbol  Input / Calc  Description 
DisplayOre:  Input  Some parameters are Ore Specific. This value indicates which ore (numbered from 1) the current list of (ore specific) parameters are relevant to. Uses can press the Prev or Next buttons to scroll between different ores. Selections made here also affect the Results tab page. 
Requirements  
Method  Whiten Crusher  The product size distribution will be determined using the Whiten empirical model which incorporates breakage and classification, based on a number of parameters. Different parameters can be used for different solids. 
ShowResults  CheckBox  If this box is ticked, then the user will see a Results tab with the selection / breakage values displayed. 
Crusher Data (Ore Independent)  
CalcKs  CheckBox  If this box is ticked, then the user enters all the parameters required to calculate the K1 and K2 values. If the box is NOT ticked, then the user specifies the K values directly. Note that K3 is specified directly by the user in both cases. 
The fields shown below are only visible if the 'CalcKs' box is ticked (except for the K values).  
ClosedSideSetting/CSS  Input  The Closed Side Setting of the crusher. 
LLEN  Input  Liner Length 
LHR  Input  Liner age 
ET  Input  Eccentric Throw 
K1, K2, K3 are calculated via 6.56.7 in MCC K1 = A0+A1*CSSA2*TPH+A3*F80+A4*LLEN K2 = B0+B1*CSS+B2*TPH+B3*F80B4*LHR+B5*ET K3 = CO (Specified directly) These parameters should be found by data fitting View "All Fields" to see additional parameters  
A0 to A4  Input  Parameters required to calculate K1: K1 = A0 + A1*CSS  A2*TPH + A3*F80 + A4*LLEN 
B0 to B5  Input  Parameters required to calculate K2: K2 = B0 + B1*CSS + B2*TPH + B3*F80  B4*LHR + B5*ET 
K1  Input/Calc  Size below which all particles escape breakage. If CalcKs is ticked this is a result field, otherwise it is an input field. 
K2  Input/Calc  Size above which all particles are crushed. If CalcKs is ticked this is a result field, otherwise it is an input field. 
K3  Input  Exponent. This should be fixed at 2.3. 
CalcT10  CheckBox  If this box is ticked, then the user must enter all of the parameters required to calculate T10. If the box is NOT ticked, then the user specifies T10 directly. 
The fields shown below are only visible if the 'CalcT10' box is ticked (except for the T10 value).  
D0 to D3  Input  Parameters required to calculated T10: T10 = D0  D1*CSS + D2*TPH  D3*F80 These fields are only visible if 'CalcT10' is ticked. 
T10  Input/Calc  10% Passing. 
Calculated T values  
Ti  Calc  The calculated T values will be displayed here. 
BreakageAtSize  Input  
Ore Specific Data  One set for each ore  
Ti data  Input/Calc  The user enters the required data for the General appearance function for the crusher model into this table. 
Tag / Symbol  Input / Calc  Description/Calculated Variables / Options 
Display Ore  Input  The user may type in the required solid index, or use the 'Prev' and 'Next' buttons to scroll between defined solids. 
NoLoadPower/Pn  Input  The power draw of the Whiten Crusher with no feed. 
Scaling/A  Input  The dimensionless scaling factor for the actual crusher. 
TotalPendulmPower/Pp  Calc  The calculated Pendulum Power. 
CrusherPower/Pc  Calc  The crusher power draw with the feed load. 
Pendulum ECS Data: kWh/ton. These values are per solid ore type (use the scroll buttons to move between ore types)  
Init Size (mm)  Input  The initial material size for each of 3 tests. 
T10=10  Input  The T10 value for each of the 3 tests. 
T10=20  Input  The T10 value for each of the 3 tests. 
T10=30  Input  The T10 value for each of the 3 tests. 
Results Page
This tab will be visible when the Method selected is 'Whiten Crusher'. See Model Theory  Whiten Crusher Method for more information.
Crusher Page  Selection/Breakage
The fields that will be visible when the Method selected is 'Selection/Breakage'.
Tag / Symbol  Input / Calc  Description/Calculated Variables / Options 
ShowRecalc  CheckBox  Tick this box to show when data arrays are recalculated. 
Impact Methods  
Impact. This method uses simple user defined Impact velocity.  
ImpactVelocity  Input or Result  If the 'ImpactType' = Impact, then the user will specify this parameter. It is calculated for the Hammer Mill. 
Hammer. The impact velocity is calculated from the rotation speed and diameter.  
RotorSpeed  Input  Rotational Speed for a Hammer Mill. 
RotorDiameter  Input  Rotor Diameter for a HammerMill. 
Breakage Probability Selection Methods  
VogelPeukert. Uses the Vogel Selection Function. The user enters the following variables for each ore type.  
fMat  Input  Material Parameter that characterises the resistance of particulate material against fracture in impact comminution. 
Wm_min  Input  Massspecific threshold energy for particle breakage, i.e. the specific energy which a particle can take up without fracture. 
k  Input  Number of impact events. 
Austin. Uses the Austin Selection Function. The user enters the following variables for each ore type.  
S1  Input  Material Parameter. 0 <= S1 <= 1 
x1  Input  Minimum particle size. 0 <= x1 <= Maximum particle size in the feed stream. 
a  Input  Parameter. 0 <= a <= 1 
User. The user enters their own Selection data on the Selection/Breakage tab.  
Breakage Functions  
ReidSteward. Uses the ReidSteward Breakage Function. The user enters the following variables for each ore type.  
Phi  Input  Experimentally determined material parameter. 
Gamma  Input  Experimentally determined material parameter. 
Beta  Input  Experimentally determined material parameter. 
Austin. Uses the Austin Breakage Function. The user enters the same variables as for the ReidSteward method, shown above.  
VogelPeukert. Uses the VogelPeukert Breakage Function. The user enters the following variables for each ore type.  
c  Input  Experimentally determined material parameter. 
d  Input  Experimentally determined material parameter. 
MinFragSize  Input  The minimum size to which the material can break. 
Tavares . Uses the Tavares Breakage Function. The user enters the following variables for each ore type.  
alpha  Input  Material Parameter based on experimental data. 
t10  Input  Material Parameter. 
Logarithmic. Uses the Logarithmic Breakage Function. The user enters the following variable for each ore type.  
A  Input  Material Parameter. 
Weibull. Uses the Weibull Breakage Function. The user enters the following variables for each ore type.  
n  Input  User Parameter: n>0 
xu  Input  User Parameter. 
xStar  Input  User Parameter: xStar>xu 
User. The user enters their own Breakage data on the Selection/Breakage tab.  
NStressEvents  Input  The number of Multiple Impact Events. See Multiple Impact Events. This may be an integer, or it may be a fractional value, such as 1.5. 
If the user requires internal classification, then they can tick the 'Classification' box and the following fields all relate to these calculations.  
Classification  Checkbox  If this box is ticked, then the unit will apply internal classification. 
ClassificationType  Napier Munn  Uses the Napier Munn classification. 
Whiten  Uses the Whiten classification.  
User  The user enters their own classification data on the Selection/Breakage tab.  
PostScreen  Input  Transfer Model for closed loop classifier. 
K1, K2, K3  Input  Parameters for Napier Munn classification model. 
Selection/Breakage Page
The selection, breakage fraction, cumulative breakage (and classification if enabled) data is available in tabular form. When User options are selected data may be entered manually.
If User options are selected, the parameters can be entered manually (or by user calculation in a PGM):
Tag / Symbol Input / Calc Description/Calculated Variables / Options Display Ore Input Which ore to display if multiple ores are present in feed. DisplayCumulative CheckBox Display Cumulative breakage
Crusher Page  Test Data
Adding this Model to a Project
Insert into Configuration file
Sort either by DLL or Group.

DLL: 
Comminution.dll

→ 
Units/Links 
→ 
Size Alteration: Crusher2 
OR 
Group: 
Size Distribution 
→ 
Units/Links 
→ 
Size Alteration: Crusher2 
See Project Configuration for more information on adding models to the configuration file.
Insert into Project

Insert Unit 
→ 
Size Alteration 
→ 
Crusher2 
See Insert Unit for general information on inserting units.