Sargon Engineering has developed a SysCAD model of an alumina refinery, based on detailed design criteria supplied by industry experts.
Meeting Client Needs
Sargon Engineering works co‐operatively with clients in order to achieve credible process simulations. Once a base case scenario has been completed, we modify and reconfigure model design elements as the process is optimised and project development unfolds. Sargon Engineering is responsive to client schedule needs. We are able to adapt readily and efficiently to changes in our clients’ priorities to keep their project on schedule and on the right track. Our unique flexibility enables us to run test cases and modified models within a short time period.
The SargAl Model
Working with industry experts, we have developed a mass and energy balance model for the Bayer Process for alumina production called “SargAl”.
The SargAl model utilises SysCAD software. This software is equipped with a well proven property dataset for Bayer Process components. The software provides excellent estimates of liquid and slurry density, viscosity and boiling point elevation.
Base Case Features
The base case SargAl model is for a low temperature (Gibbsite) alumina refinery. It has the following features:
- Separate heating of slurry and spent liquor
- Final heating of digestion feed by steam injection
- Five stages of digestion flash
- Settling with seven stages of washing
- Causticisation of third washer overflow
- Precipitation utilising SSA or Fixed Yield methods
- Co‐precipitation of oxalate with oxalate removal by hot wash of fine seed
- Classification with seed recycle
- Heat interchange
- Evaporation (split system)
The model can be manipulated to achieve a set of client specified design criteria in terms of:
- A/C Out of Digestion
- A/C to Precipitation
- A/C from Precipitation
- Caustic Soda losses to mudlakes
- C to Mill
- C to Precipitation
- Solids concentration in final precipitator
The SargAl model can be reconfigured to client requirements, including:
- High temperature (Boehmite, Diaspore) digestion
- Causticisation position
- Fluid Bed Calcination
- Number of washers
- Holdup in precipitation and number of precipitators
- Method of oxalate destruction, e.g. Liquor burning
- Configuration of evaporation train
- Ancilliary plant such as power house, VOC removal and lime preparation.
A comminution model for bauxite ore crushing and grinding is not provided but can be arranged separately.
The usual process package resulting from a SargAl modeling assignment is as follows.
Client specifications and design criteria.
The flowsheets represent the client’s requirements for the specific Alumina refinery configuration.
Tables of data containing stream parameters, for example:
- Stream number
- Stream label
- Mass flow
- Estimated viscosity (for liquors and slurries)
- Bayer Liquor properties including TOC and Oxalate
The client has a choice of expressing concentrations equivalent to Na2CO3, Na2O or as individual component concentrations. Alumina load can be expressed as A/C or RP. Some testwork will be required to establish viscosity relations for washer underflow streams.
A tabulation of design criteria specified. The value achieved in the model is shown alongside the design criteria value. This provides a detailed ‘health check’ of the model.
Major Calculated Model Results
Major calculated model results may include:
- Alumina hydrate production
- Live steam and flash steam condensate production
- Liquor circulation rate
- Caustic consumption
- Raw water make‐up
- Red mud production
Balances for water, caustic soda or any other component can be presented. The water balance is always presented as a supplementary validation of the model.
In addition to process modeling, Sargon Engineering offers a range of complementary services.
- Optimisation of energy use for power and steam production
- Optimisation of use of Caustic, Lime and Water
- Conceptual Cost Estimating for Capital Cost Estimates and Operating Cost Estimates
- Preparation of PFDs and area layouts, including 3D design and full plant CAD modeling
Staff engineers have previously worked on plant operations or plant designs associated with the alumina refineries at Kwinana and Lanjigarh.
A portion of Sargon Engineering’s “SargAl” alumina model (evaporation circuit) is shown below: