Irreversible reaction

Gibbsite digestion

Al(OH)3+NaOHNaAlO2+2H2O

Direction
Irreversible
Processes
1
Stated as
Fixed conversion
Heat of reaction
ΔH = 20,590 kJ/kmol (one process)
Element balance
Checked: balances
As the processes state itStoichiometry, conversions, heats of reaction and catalyst windows are taken from each process's files with their provenance. The build checks only that each process's equation balances in every element, from the process's own component formulas; it does not check the numbers. A process's design maturity applies to them.

Species

SpeciesNameCASRoleCoefficient
Al(OH)3Gibbsite14762-49-3reactant-1
NaOHSodium hydroxide1310-73-2reactant-1
NaAlO2Sodium aluminate (dissolved; NaAl(OH)4 less 2 H2O)1302-42-7product1
H2OWater7732-18-5product2

Also stated as NaAlO2 + 2 H2O → Al(OH)3 + NaOH.

In the processes

  • Alumina by the Bayer process (3000 t/d smelter-grade alumina, concept)Concept · not reviewed

    DIG · Gibbsite digestionAl(OH)3(s) + NaOH(aq) → NaAlO2(aq) + 2 H2O(l)

    Stated as
    Fixed conversion
    Phase
    mixed
    Element balance
    Balances in every element
    Conversion
    98 % of AlOH3 (assumed: D-004: 98 % of the gibbsite dissolved at 418 K to a blow-off A/C of 0.70; diaspore/boehmite and quartz not attacked at this temperature)
    Heat of reaction
    ΔH = 20,590 kJ/kmol at 298.15 K, as written (assumed: formation enthalpies Al(OH)4-(aq) -1502.5, Na+(aq) -240.12, NaOH(aq) -470.11 kJ/mol (NBS tables), gibbsite -1293.1 kJ/mol (Robie and Hemingway 1995))

Sources

What the processes cite for this reaction, each source once: for the reaction itself, its conversion, its heat of reaction or its catalyst. As the processes write them; DOIs, US patent numbers and web addresses are linked.

  1. D-004: 98 % of the gibbsite dissolved at 418 K to a blow-off A/C of 0.70; diaspore/boehmite and quartz not attacked at this temperature

    For the conversion · cited by Alumina by the Bayer process (3000 t/d smelter-grade alumina, concept)

  2. formation enthalpies Al(OH)4-(aq) -1502.5, Na+(aq) -240.12, NaOH(aq) -470.11 kJ/mol (NBS tables), gibbsite -1293.1 kJ/mol (Robie and Hemingway 1995)

    For the heat of reaction · cited by Alumina by the Bayer process (3000 t/d smelter-grade alumina, concept)