![Crystallization of (NH₄)₂SO₄ Crystallization of (NH₄)₂SO₄](https://ebner-co.de/wp-content/uploads/2023/12/mehrstufige-ammoniumsulfat-kristallisationsanlage-480x346.jpg)
Evaporation of Aluminate Solution
![Plant for flash evaporation Plant for flash evaporation](https://ebner-co.de/wp-content/uploads/2023/12/anlage-zur-entspannungsverdampfung-560x367.jpg)
In the Bayer process for extracting bauxite with aqueous sodium hydroxide to produce aluminum oxide, a so-called thin liquor is generated during the process. This liquor, mainly consisting of NaOH and Al(OH)₃, is referred to as aluminate liquor or sodium aluminate liquor.
To reuse the liquor for the bauxite extraction process, it needs to be concentrated.
![Schematic diagram of an evaporation plant as a falling film evaporator Schematic diagram of an evaporation plant as a falling film evaporator](https://ebner-co.de/wp-content/uploads/2023/12/prinzipschema-verdampfungsanlage-als-fallfilmer-560x374.jpg)
For evaporation, the principle of multi-effect evaporation in co-current flow and the principle of flash evaporation have predominantly been established.
Developments tend towards single-stage plants with compression, depending on the components of the solution and the desired evaporation degree. Evaporation plants with mechanical vapor recompression are possible, and plants with thermal vapor recompression have been realized.
![Plant for flash evaporation Plant for flash evaporation](https://ebner-co.de/wp-content/uploads/2023/12/anlage-zur-entspannungsverdampfung-560x367.jpg)
![Evaporator and external separator Evaporator and external separator](https://ebner-co.de/wp-content/uploads/2024/01/verdampfer-und-aussen-liegender-abscheider-560x420.jpg)
Depending on the solution’s ingredients, the plants can either be designed as falling film plants or, in cases of increased fouling behavior of the heat exchanger surfaces, as forced circulation plants.
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Frequently Asked Questions
What should be considered in evaporation plants for aluminate liquor?
Evaporation plants for sodium aluminate liquors, or aluminate liquors in general, must be designed to avoid reaching the salt crystallization zone of the ingredients (e.g., NaAlO₂ and its hydrates or Na₂CO₃ and its hydrates).
Why aren’t all plants executed with falling film evaporation?
It varies from case to case, depending on the fouling behavior of the heat exchanger surfaces.
If fouling is expected, the zone of evaporation and thus the concentration of the solution should not occur on the heat-transferring tubes themselves, as is the case with falling film evaporators.
Plants with a separate heat transfer zone in a heat exchanger and the the evaporation zone in the evaporator are preferred.
Which substances can cause fouling?
Typically, (sodium) silicates, (sodium) carbonates, and calcium salts are responsible for fouling.
Other applications
![Crystallization of (NH₄)₂SO₄ Crystallization of (NH₄)₂SO₄](https://ebner-co.de/wp-content/uploads/2023/12/mehrstufige-ammoniumsulfat-kristallisationsanlage-480x346.jpg)
![Crystallization of FeSO₄ 7H₂O Crystallization of FeSO₄ 7H₂O](https://ebner-co.de/wp-content/uploads/2023/12/aufbau-einer-vakuum-kuehlkristallisationsanlage-2-480x360.jpg)
![Crystallization of K₂SO₄ (SOP) Crystallization of K₂SO₄ (SOP)](https://ebner-co.de/wp-content/uploads/2023/12/produktionsanlage-fuer-kaliumsulfat-k2so4-als-sop-480x320.jpg)
![Crystallization of KCl (MOP) Crystallization of KCl (MOP)](https://ebner-co.de/wp-content/uploads/2023/12/oberer-teil-des-kcl-kristallisators-480x360.jpg)
![Crystallization of LiCl Crystallization of LiCl](https://ebner-co.de/wp-content/uploads/2023/12/verdampfung-und-kristallisation-von-licl-3-480x271.png)
![Crystallization of Li₂CO₃ Crystallization of Li₂CO₃](https://ebner-co.de/wp-content/uploads/2023/10/Startslider_Source-2-480x233.png)
![Crystallization of Li₂SO₄ H₂O Crystallization of Li₂SO₄ H₂O](https://ebner-co.de/wp-content/uploads/2023/12/verdampfungs-kristallisationsanlage-fuer-lithiumsulfat-li2so4-480x384.png)
![Crystallization of LiOH H₂O Crystallization of LiOH H₂O](https://ebner-co.de/wp-content/uploads/2023/12/verdampfung-und-kristallisation-von-lioh-h2o-480x360.png)
![Crystallization of MgSO₄ 7H₂O Crystallization of MgSO₄ 7H₂O](https://ebner-co.de/wp-content/uploads/2023/12/anlage-zur-kristallisation-von-mgso4.7h2o-480x270.jpg)
![Crystallization of Na₂CO₃ or Soda Crystallization of Na₂CO₃ or Soda](https://ebner-co.de/wp-content/uploads/2023/12/vakuum-kuehlkristallisationsanlage-480x316.jpg)
![Crystallization of Na₂SO₄ or Glauber’s Salt Crystallization of Na₂SO₄ or Glauber’s Salt](https://ebner-co.de/wp-content/uploads/2023/12/vakuum-kuehlkristallisation-von-glaubersalz-na2so4-10h2o-480x360.jpg)
![Crystallization of NaCl (Vacuum Salt) Crystallization of NaCl (Vacuum Salt)](https://ebner-co.de/wp-content/uploads/2023/12/einbringen-des-nacl-kristallisators-480x360.jpg)
![Evaporation of CaCl₂ Solution Evaporation of CaCl₂ Solution](https://ebner-co.de/wp-content/uploads/2023/12/verdampfungsanlage-fuer-cacl2-loesung-im-aufbau-480x640.jpg)
![Evaporation of MgCl₂ Solution Evaporation of MgCl₂ Solution](https://ebner-co.de/wp-content/uploads/2023/12/umwaelzleitung-und-umwaelzpumpe-480x320.jpg)
![Evaporation of Spin Bath & Crystallization of Sodium Sulfate Evaporation of Spin Bath & Crystallization of Sodium Sulfate](https://ebner-co.de/wp-content/uploads/2023/12/vakuum-kuehlkristallisationsanlage-fuer-glaubersalz-na2so4-10h2o-480x320.jpg)