# Solvent Extraction Unit

Jump to navigation Jump to search

Navigation: Main Page -> Models -> Mass Separation Models

This Page is for SysCAD 138 and later. For earlier versions, please see Solvent Extraction Unit 137.

## General Description

The Solvent Extraction unit will mix perfectly all the input streams, complete species transfer across phases, then separate the output based on individual phase or density.

User can set up the unit for solvent extraction or organic stripping. The model also allows imperfect separation of products, to do this, specify aqueous loss in organic and/or organic loss in aqueous.

### Defining species

User is responsible for setting up a suite of species which accurately portrays the application that is being evaluated. As the separation of the mixture will be based on individual phase or density, we recommend defining all aqueous species with individual phase (aq) and all organic species with individual phase (o). If using separation by density, please ensure the organic species are defined with a lower density than the aqueous species.

Some example species are listed below:

• Aqueous species (aq): H2O, H2SO4, CuSO4, FeSO4, Fe2[SO4]3
• organic species (o): Kerosene, RH, R2Cu, R2Fe, R3Fe.
• This suite of species is typically set up for chelating type of organic solvents such as the LIX hydroxy oxime copper extractants available from the Henkel Corporation i.e. LIX 64N, 65N, 860, 864, 865, and 622.

### Species transfer across phases

The transfer of the species across phases (Aqueous->Organic OR Organic->Aqueous) can be specified via the reaction block.

For example, for extraction of Cu from the aqueous into the organic phase, we can use the following reaction:
2RH(o) + CuSO4(aq) = R2Cu(o) + H2SO4(aq)
Or, in the case of stripping of Cu from the organic phase back into the aqueous phase, we can use the following reaction:
R2Cu(o) + H2SO4(aq) = 2RH(o) + CuSO4(aq)

The extent of the reaction be either be a user specified value or by reading from the McCabe Thiele diagram isotherms.

• To specify the reaction extent directly in the reaction, set the ExtractionMethod = 'None',
• To define and read values from a McCabe Thiele diagram, ExtractionMethod = 'Isotherm2'. (Isotherm2 is the improved method available in SysCAD 138)

NOTES:

1. The Isotherm (original) is retained here for backward compatibility purposes only, this method has known issues with steep operating lines, recommend using Isotherm2 method.
2. Please see model theory for more detail on how to use the isotherm feature.

### Phase Separation

The user may choose to separate the mixture based on either Individual Phase or density:

• IndPhase to Organic: The user specifies the Individual phase that will report to the Organic stream.
Note: All solids and other liquid phases will classed as Aqueous.
• Density: The user specifies the density of separation. In this case the aqueous species are normally denser than the user defined density of separation and the organic species are less dense. e.g. with a separating density of 950 kg/m3, water and all dissolved aqueous species will report to the aqueous phase and the organic species, normally with densities less than approximately 850 kg/m3, will report to the organic phase.
Note: Solids will also split on density.

### Entrainment

The user may also specify the entrainment of the two different liquids:

• Aqueous in the Organic stream. Note this will also include any solids that are in the aqueous phase; and
• Organic in the Aqueous stream.

### Heat Loss

User may specify heat loss to the environment by switching on the EnvironHX option. This heat loss will occur after reactions have been completed.

### Diagram

The diagram shows the default drawing of the Solvent Extraction unit, with all of the streams that have to be connected for the unit to operate.

The physical location of the streams connecting to the Solvent Extraction unit is unimportant. The user may connect the streams to any position on the unit.

## Inputs and Outputs

 Label RequiredOptional InputOutput Number of Connections Description Min Max. Aqueous Inlet 1 Required In 1 20 Aqueous feed to Solvent Extraction unit. Organic Inlet 1 Required In 1 20 Organic feed to Solvent Extraction unit. Aqueous Outlet Required Out 1 1 Aqueous outlet from Solvent Extraction unit. Organic Outlet Required Out 1 1 Organic outlet from Solvent Extraction unit. Vent Optional Out 0 1 Vent Stream. (Vapour Only)

## Behaviour when Model is OFF

If the user disables the unit, by un-ticking the On tick box, then the following actions occur:

• All streams connected to the 'Aqueous' inlet will flow straight out of the 'Aqueous' outlet;
• All streams connected to the 'Organic' inlet will flow straight out of the 'Organic' outlet;
• No reactions will occur.

So basically, the unit will be 'bypassed' without the user having to change any connections.

## Model Theory

The Isotherm Method of modelling a Solvent extraction unit is based on the McCabe-Thiele method. It assumes that the operating line on the xy diagram, representing a single solvent extraction stage, is linear. The diagram below illustrates the graphical representation of the unit:

1. The Equilibrium line is determined from experimental test data
• For extraction, the x axis is the concentration of the primary metal in the aqueous phase and the y axis is the concentration of the primary metal in the organic phase.
• For stripping, the x axis is the concentration of the primary metal in the organic phase and the y axis is the concentration of the primary metal in the aqueous phase.
2. The model assumes the total volume in each phase remains constant, the simplified linear operating line can be presented as:
• $\mathbf{\mathit{ C_{P_{y}} = C_{F_{x}} * \frac{Q_x}{Q_y} + I }}$
• Where:
$\mathbf{\mathit{ C_{P_{y}}}}$: is the product elemental concentration presented in the y-axis (for extraction, this is the organic product)
$\mathbf{\mathit{ C_{F_{x}}}}$: is the feed elemental concentration presented in the x-axis (for extraction, this is the aqueous feed)
$\mathbf{\mathit{ \frac{Q_x}{Q_y} }}$: is the slope, volumetric flow ratio of the two streams. (for extraction, this is A/O)
$\mathbf{\mathit{ I }}$: is the Y-intercept.
3. The Y-intercept of the operating line is solved by SysCAD using the data given.
• It is called MinOrgConc in the case of extraction, and MinAqsConc in the case of stripping.

NOTES:

• The equilibrium line is usually based on elemental concentration. Please see example 1 below on how to read the isotherm data.
• In some cases, the total elemental concentration can not be used directly, for example, Fe can be in the form of Fe2+ and Fe3+. If user only wish to get the Fe2+ concentration and not the total Fe concentration, then "User Calc" should be used. To use this option, user-specified calculations must exist to allow mapping of the aqueous and organic values. Please see example 2 on how to set up user calculations.
• The model is not currently sensitive to pH and assumes that the pH is correct for a particular equilibrium isotherm.
• User can adjust the stage efficiency to emulate cases where there is insufficient contact time to achieve perfect equilibrium.

### Using Isotherms

Set up the isotherm data

• SolventExtraction Tab: set ExtractionMethod = Isotherm2,
• SolventExtraction Tab: set Mode to Extraction or Stripping.
• To enter the equilibrium curve, go to the new tab called "isotherm", specify the number of data points by setting the length.
• Take care to enter the correct concentration in to the correct column: for Extraction it is Aq | Org, for Stripping it is Org | Aq
• The data can also be loaded from or saved to a csv file (comma separated text file).

Set up the reaction

• The data retrieved from the isotherm will be applied to the first reaction only, user must make sure the first reaction contains the element of interest.
For example: $\mathbf{\mathrm { CuSO_4(aq) + 2 RH(o) = H_2 SO_4(aq) + R_2 Cu(o)}}$
• The extent species used to adjust for Reaction 1 should be set in the ExtentSpecies field. SysCAD will adjust this species reaction extent using values read from the isotherm diagram.
Extent:Fraction$\mathbf {\mathrm{ CuSO_4(aq) = 0.5}}$
• The reaction file may contain other reactions, the reaction extent for these reactions must be set by the user.

Defining Isotherm Component

#### EXAMPLE 1: Based on total Cu concentration by phase

• Set the IsothermComponent to "Element" and PrimaryMetal to "Cu"
• The Extent Species selected must contain the primary metal element, if not, SysCAD will return an error. (In this example, the extent species for reaction 1 is CuSO4(aq) and the Primary Metal is Cu.)
• All concentration values shown in the Results section will be based on Cu.
• This is the total Cu concentration by phase, so if more than one Cu species is present, the Cu concentration from all species are accounted for.
• The reaction extent of reaction 1 is then adjusted to give the desired concentrations.

Using the isotherm given in Model Theory, we have:

1. Cu concentration in aqueous feed = 1.7 g/L (green vertical line)
2. Cu concentration in organic feed = 2.96 g/L (green horizontal line)
3. The operating line's slope is defined by feed stream volume ratio, the operation line y-intercept solved by SysCAD (blue line)
• Start from the input Aqueous concentration, 1.7 g/L,
• move vertically up the red line to the operating line, then horizontally to the Equilibrium line (magenta Line).
• find the equilibrium values of the Copper concentrations in the exiting Aqueous and Organic streams to be Cu(aq) = 0.4 g/L and Cu(o) = 5 g/L respectively.

#### EXAMPLE 2: Based on User Defined calculations

In some cases, the total elemental concentration may not be used directly, for example, Fe can be in the form of Fe2+ and Fe3+. If user only wish to get the Fe2+ concentration and not the total Fe concentration, then user-specified calculations must be used for mapping of the required aqueous and organic portion, in this example, we will only use Fe2+ while ignoring Fe3+.

• If the user calculations have not been defined yet, please do the following:
1. Save and close the project.
2. Menu command: Edit | Project Configuration - step 2 of 2 | Calculations:
• On the User Property Calculations section (top half), add two user defined properties to represent the required mass flow of the element in the aqueous and the organic phase respectively.
• Examples of these are shown in the following picture, all concentration values shown in the Results section will be based on these calculated mass flow.
3. Save the configuration file, reopen the project and resume configuration of the solvent extraction unit.
• Set the IsothermComponent to "User Calc",
• AqQmUserCalc: select the user property calculation from the drop-list that represents the aqueous mass flow for the required element (eg Fe2+ in aqueous phase)
• OrgQmUserCalc: select the user property calculation from the drop-list that represents the organic mass flow for the required element (eg Fe2+ in organic phase)
• All concentration values will be based on the user calculation.
• This is NOT the total Fe concentration by phase, so only Fe2+ from FeSO4(aq) or R2Fe(o) is considered.
• The reaction extent of reaction $\mathbf{\mathrm { FeSO_4(aq) + 2 RH(o) = H_2 SO_4(aq) + R_2 Fe(o)}}$ is then adjusted to give the desired concentrations.

NOTE:

1. This method relies on correctly defined User Property Calculations. Please check the calculations if results do not match expected values.
2. The user calculation should be defined in the user property calculation section, not the user species calculation section.

### Isotherm data and operating condition issues

When using the isotherm data, user needs to keep in mind that there are a number of conditions where the operating condition may not fall on the isotherm curve:

• Limited by other species that contain the same primary metal - the feed may contain multiple species with the specified Primary Metal. This could cause the metal concentration be higher than the isotherm data.
• Limited by reactions - Reaction file may contain multiple reactions, but only Reaction 1 is used to adjust the metal concentration, it is possible that even after fully reacting the Reaction 1 species, the isotherm concentration cannot be achieved.
• Feed stream concentration too high - operating point falls outside of the isotherm curve.

When operating point is out of range, the concentration will be limited by the isotherm data. A warning message will be displayed, for example:

"W:Concentration (Y value 10.0555) from operating curve is greater than the maximum specified Isotherm data point. (Max 8.5 used)"
• Extraction - SysCAD will tried to satisfy the loaded organic concentration by adjusting Reaction 1 reaction extent. The spent aqueous concentration will be by balance.
• Stripping - SysCAD will tried to satisfy the stripped aqueous concentration by adjusting Reaction 1 reaction extent. The organic concentration will be by balance.
• If the reaction extent is being limited (0% to 100%), then it is possible that both the aqueous and organic concentrations will not fall on the isotherm curve.
• When the reaction 1 extent is being limited, the following warning messages will be displayed: "W:R1 Extent driven to greater than 100"

## Data Sections

The default access window consists of several sections:

1. SolventExtraction tab - Contains general information relating to the unit.
2. RB - Optional tab, only visible if the Reactions are enabled.
3. EHX - Optional tab, only visible if the EnvironHX is enabled.
4. Isotherm tab - The user can set up and view the isotherm.
5. QAqFeed - Optional tab, only visible if ShowAqQFeed is enabled. This page shows the properties of the mixed aqueous stream, useful when multiple aqueous feed streams are present.
6. QOrgFeed - Optional tab, only visible if ShowOrgQFeed is enabled. This page shows the properties of the mixed organic stream, useful when multiple organic feed streams are present.
7. QFeed - Optional tab, only visible if ShowQFeed is enabled. This page shows the properties of the mixed stream as the feed to the solvent extraction.
8. Info tab - Contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
9. Links tab, contains a summary table for all the input and output streams.
10. Audit tab - Contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.

### Solvent Extraction Page

Unit Type: SolventExtraction - The first tab page in the access window will have this name.

Tag (Long/Short)

Input / Calc

Description/Calculated Variables / Options

### Requirements

On Tick box If this is enabled then the unit will be in full operational mode. If this is disabled, then unit will be 'inoperative', as described in Inoperative Mode.
SeparationMethod / SeparMethod Density The user selects the Density of Separation. All species (INCLUDING solids) that have a density LESS than this density will report to the organic outlet. All species with a density GREATER than this density will report to the Aqueous outlet.
IndPhase to Organic The user selects the Individual liquid Phase(s) (usually (o)) that reports to the organic phase. All solids and other liquid phases will report to the Aqueous phase.
SeparDensity / SeparRho Input Visible if SeparMethod = 'Density'. The required separation density.
This must be a value between the density of the aqueous and organic streams.
Note: The density of water is a function of temperature, and is often less than 1000 kg/m3; therefore it is safer to specify a separation density below 950 kg/m3.
List of Liquid Individual Phases Tick Boxes Visible if SeparMethod = 'IndPhase to Organic'. The user must select one or more Individual liquid phases that will report to the Organic outlet. Normally, the user will select the 'o', or 'org' phase. All other liquid phases will report to the Aqueous outlet.
(The user defines the Individual phase for each species in the Species Database. Normally organic species are defined to have an individual phase of 'o', or 'org'. Please see Individual Phase Label for information on how to change the Individual Phase of a species)
Entrainment Feed Loss The Aqueous/Organic loss is defined as a percentage of the aqueous (or organics) in the unit after all the reactions have been completed. NOTE: This is feed to the separator section, not the mixer section.
Product Fraction The Aqueous/Organic loss is defined as mass concentration in the outlet stream, normally in ppm.
AqueousLossReqd / AqsLossReqd Input Visible with the Feed Loss Entrainment method. The mass fraction of Aqueous liquid in the unit lost to the Organic product stream.
Note that solids in the Aqueous phase will also report to the Organic stream when an entrainment value is specified.
OrganicLossReqd / OrgLossReqd Input Visible with the Feed Loss Entrainment method. The mass fraction of Organic liquid in the unit lost to the Aqueous product stream.
AqueousInOrgReqd / AqsInOrgReqd Input Visible with the Product Fraction Entrainment method. User specified the mass concentration of aqueous (normally in ppm) in the organic outlet stream.
Note that solids in the Aqueous phase will also report to the Organic stream when an entrainment value is specified.
OrganicInAqsReqd / OrgInAqsReqd Input Visible with the Product Fraction Entrainment method. User specified the mass concentration of organics (normally in ppm) in the aqueous outlet stream.
ExtractionMethod / Method None The model does not use Isotherms to determine the extent of the extraction or stripping reaction.
The user sets the extent/s of the reaction/s manually.
Isotherm (Original) NOTE: This is the method implemented in SysCAD 137 and earlier. This method has known issues when the slope of the operating line is steep. The short comings of this implementation has been rectified in method Isotherm2. We recommend user changing to the new method. This method is retained here for backward compatibility purposes only.
Isotherm2 This is the recommended method for SysCAD 138. The model uses Isotherms to determine the extent of the extraction or stripping reaction.
• Reactions will be switched on by SysCAD if the isotherm2 method is chosen, user must still specify the reaction file and the reaction/s,
• The extent of the first extraction or stripping reaction will be adjusted by the model to meet the concentration read from the isotherm.
• The reaction file may contain more than one reaction, user must set the required extents of the other reactions. NOTE that the presence of other reactions will affect the results (end results may not match the isotherm concentrations).
The following fields assume Isotherm2 Method is chosen.
AllowOveride Tickbox This allows the user to override the reaction extent calculated by the isotherm and manually set the reaction extent on the RB tab page. A warning is given in the "Condition" field to remind user override is in use.
Mode Extraction select this mode for extraction of species from aqueous --> organic phase.
Stripping select this mode for stripping the species from organic --> aqueous phase.
StageEfficiency / StageEff Input The efficiency of the solvent extraction stage. The concentration values from the isotherm will be adjusted to take into account the two phases may not be in contact long enough to achieve perfect equilibrium.
ExtentSpecies / ExtentSp Input The reaction species that contains the primary metal, e.g. for Extraction it may be CuSO4, and for Stripping R2Cu.
IsothermComponent Element If the isotherm data is based on a selected element, and its concentration represents the total elemental concentration in the that phase, then set this to element.
User Calc In some cases, the total elemental concentration may not be used directly, for example, Fe can be in the form of Fe2+ and Fe3+. If user only wish to get the Fe2+ concentration and not the total Fe concentration, then user specified calculations should be used. Please see example 2 for more information on how to set up the user calculations.
Primary Metal List Not visible with the "User Calc" option. User can select an element from the available list. If using the isotherm2 method, this should be the element for which the isotherm data is based on. For example, if the isotherm data is for Cu, then we would select Cu as the element here.
• The concentration used will be the total concentration of the selected element. Therefore, if there are more than one Cu species present in the same phase, the Cu concentration will include all the Cu species, not just the species used in reaction 1.
• This selection is optional for the method "None", however it is useful to set this so that the feed and product concentrations can be shown.
AqQmUserCalc List Visible with the "User Calc" option. Using the example of Fe2+, if the concentration should be based on Fe2+ from species FeSO4(aq) only, then user must define a user property calculation for Fe2+ mass flow in the aqueous phase. This user property calculation name should be set here.
• The selection list will show the user property calculation based on mass flow only.
• Please see example 2 for more information on how to set up the user calculations.
OrgQmUserCalc List Visible with the "User Calc" option. Using the example of Fe2+, if the concentration should be based on Fe2+ from species R2Fe(o) only, then user must define a user property calculation for Fe2+ mass flow in the organic phase. This user property calculation name should be set here.
• The selection list will show the user property calculation based on mass flow only.
• Please see example 2 for more information on how to set up the user calculations.
Reactions On/Off The user may turn the reactions 'On' or 'Off'. If this is 'On' then the RB tab page will become visible. Reactions will be switched 'On' by SysCAD if the one of the isotherm method is chosen.
EnviornHX On/Off The user may turn the environment heat exchange 'On' or 'Off'. If this is 'On' then the EHX tab page will become visible. The heat exchange will occur after the reactions have taken place.

### OperatingP...

Method Atmospheric outlet streams will be at Atmospheric Pressure. The atmospheric pressure is calculated by SysCAD based on the user defined elevation (default elevation is at sea level = 101.325 kPa). The elevation can be changed on the Species tab page of the Plant Model.
AutoDetect If there are any liquids AND no vapours present in the feed, outlet streams will take the highest pressure of the feeds. Else (eg. some vapours present) outlet streams will take the lowest pressure of the feeds.
LowestFeed outlet streams will take the lowest pressure of the feeds.
HighestFeed outlet streams will take the highest pressure of the feeds.
RequiredP outlet streams will be at the user specified pressure.
IgnoreLowQm Tick Box This option is only visible if the AutoDetect, LowestFeed or HighestFeed methods are chosen. When calculating the outlet pressure and temperature of the tank, SysCAD will ignore the low flow feed streams should this option be selected. The low flow limit is set in the field below.
LowQmFrac Input This field is only visible if the IgnoreLowQm option is selected. This is the amount any stream contributes to the total flow. For example, if the total feed to the tank is 10 kg/s, and this field is set to 1%. Then any feed streams with less than 0.1 kg/s will be ignored in the pressure calculations.
PressureReqd / P_Reqd Input This field is only visible if the RequiredP method is chosen. This is user specified pressure.
Result Display The actual pressure used for the sum of the feeds which will also be the outlet pressure (unless further model options change the pressure).

### Options

ShowEnergyBalance Tick Box Selecting this tickbox will add a energy balance section to the bottom of the results section of this tab.
ShowQAqFeed Tick Box QAqFeed and associated tab pages (eg Sp) will become visible if this is enabled. These tabs will show the properties of the combined aqueous feed stream to the Unit.
ShowQOrgFeed Tick Box QOrgFeed and associated tab pages (eg Sp) will become visible if this is enabled. These tabs will show the properties of the combined organic feed stream to the Unit.
ShowQFeed Tick Box QFeed and associated tab pages (eg Sp) will become visible if this is enabled. These tabs will show the properties of the combined feed stream to the Unit. These values are BEFORE any evaluation blocks such as reaction or EHX.

### Results

MinOrgConc OR MinAqsConc Output This field is only visible if the Isotherm Method has been chosen. The Y-intercept of the McCabe-Thiele operating line, MinOrgConc in the case of extraction, and MinAqsConc in the case of stripping.
NOTE this is defined by the feed streams entering the unit operation.
ReactExtent Feedback This field is only visible if the Isotherm Method has been chosen. This is the reaction extent required as appears in the RB tab page.
Displayed here for easy access.
ActReactExtent Feedback This field is only visible if the Isotherm Method has been chosen. This is the actual reaction extent achieved as appears in the RB tab page.
Displayed here for easy access.
MaxPriConcOrg Output Visible if Isotherm - Extraction Mode is chosen. Displays the maximum primary element or user compound in organic product.
This will serve as a warning for incorrectly supplied data if the results differ to those expected. In Build 137 or earlier, a similar variable called "MaxLoadedConc" was used.
MaxPriConcAq Output Visible if Isotherm - Stripping Mode is chosen. Displays the maximum primary element or user compound in aqueous product.
This will serve as a warning for incorrectly supplied data if the results differ to those expected. In Build 137 or earlier, a similar variable called "MaxStripConc" was used.
Feed Conditions
AqueousConcIn / AqsConcIn Calc The concentration of the "total primary metal element" or "user compound" in the incoming Aqueous stream.
OrganicConcIn / OrgConcIn Calc The concentration of the "total primary metal element" or "user compound" in the incoming Organic stream.
Organic/Aqueous
/ OARatio
Calc The calculated volumetric ratio of Organic to Aqueous liquid entering the unit.
Aqueous/Organic
/ AORatio
Calc The calculated volumetric ratio of Aqueous to Organic liquid entering the unit.
Product Conditions
AqueousConcOut / AqsConcOut Calc The concentration of the "total primary metal element" or "user compound" in the outgoing Aqueous stream.
OrganicConcOut / OrgConcOut Calc The concentration of the "total primary metal element" or "user compound" in the outgoing Organic stream.
AqueousInOrg / AqsInOrg Calc The mass concentration Aqueous in the organic outlet stream.
OrganicInAqs / OrgInAqs Calc The mass concentration organic in the aqueous outlet stream.
AqueousLosses / AqsLosses Calc The mass fraction of feed Aqueous loss to the organic outlet stream.
OrganicLosses / OrgLosses Calc The mass fraction of feed organic loss to the aqueous outlet stream.

### Energy Balance

This section is only visible if the ShowEnergyBalance Option tickbox is selected.

Feed.Hz (A) The total energy for the incoming streams. (all aqueous and organic streams perfectly mixed)
Reaction.Ht@0 (B) The total heat of reaction of the RB block.
RB.HeatFlow (C) The delta heat flow from RB - Heat exchange. (This is added via the Reaction block, if used a RHX tab will be visible)
MixAfterRB.Hz (=A-B+C) The total energy for the contents after Reactions, before EHX.
EHX.HeatFlow (D) The delta heat flow from Environmental Heat Exchanger (EHX). (This is added via the EnvironHX option, if used a EHX tab will be visible.)
Prod.Hz (=A-B+C+D) The total energy for the mixture after reactions and EHX.

### Isotherm Section

The user types in the Isotherm describing the Solvent Extraction process. See Hints and Comments.

Tag (Long/short) Input / Calc Description
Isotherm Curve
Isotherm...
The user enters the data points in the two columns on this page. For example, for extraction, Aq represents the mass fraction of solute in raffinate, and Org represents the mass fraction of solute in extract.
The model interpolates linearly between the points and extrapolates beyond the first and last points.
Length Input The number of data points. Once a number has been typed in, the X and Y columns will be visible with the required number of lines. If the data is loaded from a predefined file, the length will be automatically set to match the file length.
Data Points Index The data point index value
X axis value The Aqueous or Organic values for the Isotherm. For extraction, the x-axis is for the aqueous phase; for stripping, the x-axis is for organic phase.
Y axis value The Aqueous or Organic values for the Isotherm. For extraction, the y-axis is for the organic phase; for stripping, the y-axis is for aqueous phase.
The isotherm data can be saved to or loaded from a file.
FileName Input User specified filename, (1) to store current screen values or (2) load pre-defined values. The file should be in a CSV (comma delimited) format.
Folder Feedback When saving the data to a file, the default folder will be the current project folder unless specified otherwise by the user.
Edit Edit Button This will open the isotherm data CSV file (as entered on in the FileName field) for editing. If no filename has been specified, pressing this button will open a new XXXX.csv file for editing. XXXX is the name of the current unit operation.
Reload Load Button Only active if FileName is not empty. This will load the data points from the CSV file, replacing the current values.
Save Save Button Only active if FileName is not empty. This will save the current values to the CSV file.
Browse Browse Button Use the "Browse" button to locate the CSV file that contain the isotherm data.
 Example Extraction.csv Aq,Org 0.00,0.00 0.15,2.00 0.25,3.20 0.30,3.80 0.40,5.00 0.50,5.90 0.75,6.90 1.00,7.40 1.50,8.00 2.00,8.50 

## Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

 DLL: Separation.dll → Units/Links → Separation: Solvent Extraction (Mixer/Settler) OR Group: Mass Separation → Units/Links → Separation : Solvent Extraction (Mixer/Settler)

See Project Configuration for more information on adding models to the configuration file.

Insert into Project

 Insert Unit → Separation → Solvent Extraction (Mixer/Settler)

See Insert Unit for general information on inserting units.

## Hints and Comments

1. Check that the Separation Density specified in the model is a value between the aqueous and organic densities.
2. If the isotherm is required to be used outside the range of the data points entered, then SysCAD will linearly extrapolate from the nearest set of 2 points.
3. Isotherm data points (both Aq and Org) are expected to increase in value. Data points will be sorted automatically from lowest to highest value as the data points are entered or loaded from the file.
4. Isotherm data plot X and Y axes are in concentrations (g/L).
• For extraction, the x axis is the concentration of the primary metal in the aqueous phase and the y axis is the concentration of the primary metal in the organic phase.
• For stripping, the x axis is the concentration of the primary metal in the organic phase and the y axis is the concentration of the primary metal in the aqueous phase.
5. If the primary metal element are present in multiple species, and only selected species should be counted, then user should specify which species are included by defining "user property calculations". Please see example 2 on how to set up user calculations.