Flotation Cell

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General Description

The flotation cell perfectly mixes all the incoming Feed streams and then, based on the user configuration, calculates the amount, temperature and composition of material reporting to the product streams. The Conc Launder stream is NOT mixed with the Feed or Air stream, but is added to the Concentrate stream AFTER all the Flotation cell calculations have been performed.

If a third outlet stream is required (such as a Middlings stream), the Solids Recovery Unit is very similar in functionality to the Flotation Cell except that it optionally allows a Middlings stream to be connected. When the Middlings stream is connected, there are two configuration pages and the model works like two Flotation Cells in series.

Diagram

Flot Cell Default2.jpg

The diagram shows the default drawing of the Flotation Cell, with all of the streams that can be connected to the unit. The physical location of the streams connecting to the unit is unimportant. The user may connect the streams to any position on the unit.

Notes:

  1. For a process where the concentrate reports to the float stream in the actual plant, e.g. for the recovery of sulphur minerals, then the Float stream is the Concentrate stream. The Sinks stream is the Tailings stream in this case.
  2. For Reverse Flotation, where the concentrate reports to the sinks, the Sink stream is the Concentrate stream. The Float stream is the Tailings stream.
  3. When drawing the links, the concentrate stream may be shown coming from either the top or bottom of the unit. For example, for normal flotation the concentrate stream may be shown coming from the top and for Reverse Flotation the concentrate may be shown coming from the bottom.

Inputs and Outputs

Label Required
Optional
Input
Output
Number of Connections Description
Min Max.
Feed 1 Required In 1 20 The slurry feed/s to the unit
Conc Launder Optional In 0 10 The stream going to the Concentrate Launder of the unit.
Air Optional In 0 5 The air feed/s to the unit.
Concentrate Required Out 1 1 Concentrate outlet from the unit.
Tailings Required Out 1 1 Tailings outlet from the 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 'Feed' inlet will flow straight out of the 'Tailings' outlet;
  • All streams connected to the 'Conc Launder' inlet will flow straight out of the 'Concentrate' outlet;
  • All streams connected to the 'Air' inlet will flow straight out of the 'Vent' outlet if connected otherwise to the 'Tailings' outlet;
  • No separation will occur.
  • No sub-models will occur.

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

Model Theory

The Flotation Cell is based on user defined variables that define the solids / liquids split.

There are three Recovery methods available in this model:

  1. Grade & Recovery (previously called Overall) - The user sets the recovery and grade of the Primary Solid/Element in the concentrate stream. Primary compounds are always solid species.
    • The Primary compound/s may defined by either be a specific solid species or an element.
    • If the user selects Elemental, then:
      The user must select a Primary element. (The recovery and grade will be based on this element.)
      The user may also select a Secondary element
      The user may then select an element to Exclude from the recovered species.
      The species to be recovered must contain both the Primary and Secondary elements, but Not the Excluded element. See the example below.
    • The user may also specify the grade or recovery of up to 25 additional solid species in the concentrate stream.
  2. Mass Pull & Recovery - Only available in SysCAD 9.3 Build 137 or later. This similar to the Grade and Recovery method where the user sets recovery of the primary solid species or element. But instead of setting the grade of the primary solid species or element, the user sets the mass pull, ie. the fraction of all solid species which report to the concentrate stream.
    • The user may also specify the grade or recovery of up to 25 additional solid species in the concentrate stream.
  3. Size Recovery - this is only applicable if the user has size distribution enabled in the project and the solids in the feed to the flotation cell have size distributions. The user then sets the recovery to the concentrate in each individual size fraction for each solid species.

There are also two Concentrate Liquid Split methods available in this model:

  1. Fraction of Feed Liquids - The user sets the fraction of liquid in the feed to the flotation cell that will report to the concentrate stream.
  2. Liquid in Concentrate - The user sets the required fraction of liquid in the concentrate stream.

Note: the material entering the unit via the 'Conc Launder' inlet is NOT included in these calculations, but basically bypasses the unit and reports straight to the concentrate launder.

Example of Grade & Recovery - Elemental Recovery Method

The feed stream to the flotation cell contains the following solid species:

Cu2S(s), Cu5FeS4(s), CuFeS2(s), CuO(s), Cu2O(s), SiO2(s), CoO(s) and Ore(s)

The user sets the following:

  • The Primary element = Cu
  • The Secondary element = S
  • The Exclude element = O
  • The Recovery = 50% and Grade = 65%.

Then the model will recover to the concentrate 50% of all solid species containing both Cu and S, but not O:

Cu2S(s), Cu5FeS4(s), CuFeS2(s) will be classified as Primary species.

The remaining solids species will mainly be sent to the tailings, with sufficient material to the concentrate to ensure a grade of 65% Cu in the concentrate.

Flowchart

The following shows the sequence of events. See next heading for more information.

Flotation Cell.png

Data Sections

Summary of Data Sections

  1. FlotationCell tab - Contains general information relating to the unit.
  2. Recovery - Optional tab, only visible if the Size Recovery Method is chosen.
  3. PC - Optional tab that is visible if EB.Solubility.On and/or EB.PhaseChange@T.On is enabled in the Evaluation Block.
  4. RB - Optional tab, only visible if the Reactions are enabled in the Evaluation Block.
  5. EHX - Optional tab, only visible if the EnvironHX is enabled in the Evaluation Block.
  6. Evap - Optional tab that is visible if Evaporator is enabled in the Evaluation Block.
  7. MU - Optional tab, or multiple tabs if more than 1 Makeup is selected. Only visible if one or more Makeups are enabled in the Evaluation Block.
  8. DB - Optional tab, or multiple tabs if more than 1 Discard Block is selected. Only visible if one of more Discard Blocks are enabled in the Evaluation Block. Only available in Build 138 or later.
  9. Info tab - Contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
  10. Links tab, contains a summary table for all the input and output streams.
  11. Audit tab - Contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.

Flotation Cell Page

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

Tag (Long/Short) Input / Calc Description/Calculated Variables / Options
Common Data on First Tab Page

Requirements

On Tickbox If the model is switched off then no separation occurs and all the feed is sent to the tailings stream. If any vapour is present it is sent to the vent stream if it exists, otherwise it is also sent to the tailings stream.
TrackStatus Tickbox Enable warning messages if requirements are not met.
RecoveryMethod Overall /
Grade & Recovery
The user sets the recovery and grade of the required solid species in the concentrate stream. This does not require any Size distribution data.
Mass Pull & Recovery Only available in Build 137 or later. The user sets the recovery of the required solid species as well as the mass pull of solids to the concentrate stream. This does not require any Size distribution data.
Size Recovery The user sets the fractional recovery to the concentrate stream for each individual size interval for all species that do have size distributions. The project must contain Size distribution data.
Primary Solid
Method Solid Species User may choose a solid species as the primary species for the recovery calculations.
Element The user may choose to base the recovery to concentrate calculations on an elemental basis.
PrimarySolid List Only visible if the user has selected Solid Species for Method. List of solid species in the current project which can be chosen as the primary solid.
PrimaryElement List Only visible if the user has selected Element for Method. List of elements in the current project which can be chosen as part of the primary solids species (based on all solid species in the project).
The following two fields are only visible if the user has selected Grade & Recovery or Mass Pull & Recovery for Recovery Method AND selected Element for Method.
SecondaryElement List Optional: List of elements in the current project which can be chosen to restrict the primary solid species. If a Secondary Element is chosen, then only solid species that contain BOTH the Primary AND Secondary elements will be classified as Primary Solids.
ExcludeElement List Optional: List of elements in the current project which can be chosen to restrict the primary solid species. If an Exclude Element is chosen, then only solid species that contain the Primary (and Secondary, if selected) element, but NOT the Excluded element will be classified as Primary Solid Species. (Please see the example in Model Theory above)
PrimaryRecoveryReqd Input Only visible if the user has selected Grade & Recovery or Mass Pull & Recovery for Recovery Method. Mass Recovery of the primary solid, or element, from the Feed stream to the Concentrate stream.
PrimaryGradeReqd Input Only visible if the user has selected Grade & Recovery for Recovery Method. Mass Fraction of the primary solid, or element, in the Concentrate stream.
MassPullReqd Input Only visible if the user has selected Mass Pull & Recovery for Recovery Method. Mass Fraction of all solids in the Feed stream, which report to the Concentrate stream.
Additional Solid Species to Concentrate (Only visible if the user has selected Grade & Recovery or Mass Pull & Recovery for Recovery Method)
SolidSpeciesCount / SolSpCount Input Optional: The number of additional solid species to be specified with recoveries or grades. Up to 25 may be specified.
SecondaryMethod
(Only available in Build 138 or later)
Recovery to Concentrate The user can specify the recovery of additional solid species to the Concentrate stream.
Grade in Concentrate The user can specify the grade of additional solid species in the Concentrate stream.
For each additional solid species:
SolidSpecies / SolidSp List List of solid species in the current project which can be chosen as an additional species.
RecoveryReqd Input Only visible if the user has selected Recovery to Concentrate for Secondary Method. Mass recovery of the additional species to the Concentrate stream.
GradeReqd Input Only available in Build 138 or later. Only visible if the user has selected Grade in Concentrate for Secondary Method. Grade (mass fraction) of the additional species in the Concentrate stream.
Concentrate Liquid Split
LiquidSplitMethod Fraction of Feed Liquids User can specify the fraction by mass of liquid in the Feed that is recovered to the Concentrate stream.
Liquid in Concentrate User can specify the fraction by mass of liquid in the Concentrate stream.
LiquidToConcentrate Input Only visible if user has selected Fraction of Feed Liquids for LiquidSplitMethod. Fraction by mass of liquid in Feed that is recovered to the Concentrate stream.
ConcentrateLiqFracReqd Input Only visible if user has selected Liquid in Concentrate for LiquidSplitMethod. Fraction by mass of liquid in the Concentrate stream. Please do note that if a stream has been connected to the 'Conc Launder' connection, any material in this stream will NOT be included in these calculations. Therefore, the final liquid fraction in the Concentrate stream may be different to the value set here.

OperatingP

Method 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.
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.
RequiredP Outlet streams will be at the user specified pressure.
IgnoreLowMassFlow / 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.
LowMassFlowFrac / 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).

EB (Evaluation Block)

Solubility.On Tickbox Only visible if Solubility has been defined for at least one species in the project. Allows the user to switch on any predefined solubility curve to adjust the composition of material in the unit.
PhaseChange@T.On Tickbox Only visible if Phase Change at Temperature has been defined for at least one species in the project. Allows the user to switch on any predefined phase changes at temperature in the unit.
EvalSequence Calc The sequence in which the sub models (which are part of the evaluation blocks) will be calculated. The sequence is determined by the priority selection for the individual sub-models.
Note: If the user chooses On-AutoSequence then SysCAD will determine the sequence of the sub-models. The sequence followed will be MU1, MU2, etc., RB, EHX, Evap, DB1, DB2, etc.
Makeups Input The number of makeup blocks required. Extra dropdown options Makeup1, Makeup2, etc will be added to allow these to be switched on.
Makeup1 List This can be used to switch on the Makeup Block (MU). If this is 'On' then the associated page, MU1 becomes visible and may be configured.
Note: This field is only visible if the entry for 'Makeups' is greater then 0.
Reactions List This can be used to switch on the Reaction Block (RB). If this is 'On' then the associated page, RB becomes visible and may be configured.
Note: The user does not have to configure a reaction file, even if this block is checked.
EnvironHX List This can be used to switch on the Environmental Heat Exchanger (EHX). If this is 'On' then the associated page, EHX may become visible and may be configured.
Note: The user does not have to configure an environmental heat exchange, even if this block is checked.
Evaporation List This can be used to switch on the Evaporation Block (Evap). If this is 'On' then the associated page, Evap may become visible and may be configured.
Note: The user does not have to configure an evaporator, even if this block is checked.
Discards Input Only available in Build 138 or later. The number of discard blocks required. Extra dropdown options Discard1, Discard2, etc will be added to allow these to be switched on.
DiscardX List Only available in Build 138 or later. This can be used to switch the Discard Block (DB) on or off and prioritise it in relation to the other sub-models. If this is 'On' then the associated page, DBX becomes visible and may be configured.
Note: This field is only visible if the entry for 'Discards' is greater than 0. If there is one discard then X=1. If there are two discards, then X=1 and X=2, etc.

Results

PrimariesFound Calc List of all solid species in the project which meet the criteria specified for the primary solid species.
PrimaryRecovery Calc The actual percentage recovery achieved for the primary species.
PrimaryGrade Calc The actual percentage grade achieved for the primary species.
ConcMassPull Calc Only available in Build 137 or later. The actual percentage solid mass pull to the concentrate stream achieved .
AdditionalSolids Calc List of all solid species in the project specified as additional species.
GangueSpecies Calc List of all solid species in the project which have not been specified as either primary or additional species.
Concentrate.SolidFrac / Concentrate.Sf Calc The percent solids fraction of the concentrate stream.
Concentrate.SolidConc Calc The solids concentration of the concentrate stream.
Concentrate.SolidConc25 Calc The solids concentration of the concentrate stream measured at 25C.
Tailings.SolidFrac / Tailings.Sf Calc The percent solids fraction of the tailings stream.
Tailings.SolidConc Calc The solids concentration of the tailings stream.
Tailings.SolidConc25 Calc The solids concentration of the tailings stream measured at 25C.

Recovery Page

If the user selects Size Recovery as the Recovery Method, then an additional tab will be visible, called Recovery. This will display a table of the size intervals for all solids species in the project which has its own size distribution. The user must enter the recovery for each size interval, as shown below:

SysCAD 138 Layout (PSD in Descending Order) SysCAD 137 Layout (PSD in Ascending Order)
FlotCellSizeRecovery138.png FlotCellSizeRecovery.png

In the example shown above, the flotation cell is used to recover PbS(s) - as can be seen by the higher recoveries specified for this species. The other species are gangue solids that are recovered to the flotation concentrate in smaller fractions.

Please note that in SysCAD 138, the sizes are in descending order (largest to smallest)

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

 

DLL:

Separation.dll

Units/Links

Separation: Flotation Cell

OR

Group:

Mass Separation

Units/Links

Separation : Flotation Cell

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

Insert into Project

 

Insert Unit

Separation

Flotation Cell

See Insert Unit for general information on inserting units.

Hints and Comments

  1. If there are some solids species which the user does not want to send to the concentrate at all, then include them as additional compounds/solid species with a recovery of 0%.
  2. It is possible to over-specify the problem, i.e. if the user sets Additional Solid Species to recover to the concentrate, this may prevent the Required Grade or Mass Pull from being met.
    Note: The Required Recovery will always be achieved, but the Grade/Mass Pull do depend on feed conditions and the user defined parameters.
  3. If the Size Recovery Method is selected and there is no PSD Quality data in the feed then the model does not perform any calculations and behaves as if it was off.
  4. If a stream is connected to the 'Conc Launder' input then any material in this stream will report directly to the concentrate stream and will NOT be included in the calculations in the Flotation unit. Therefore, if the user selects 'Liquid in Concentrate' the actual concentrate liquid fraction will be different if material (usually water) is added in the stream connected to the 'Conc Launder' input.
  5. If an air stream is connected but there is no vent stream, then the user will get a warning but the model will still function.
  6. If there is no vent stream, all vapours will be sent to the concentrate stream.
  7. The user cannot choose the same species as both a primary solid species and an additional solid species or twice as an additional compound/solid species. In either of these cases the model will not run and the user will be given an error message.

Example Project

Please see Milling and Flotation Project or Milling and Magnetic Separation Project