The kinetics of gibbsite dissolution in NaOH

Pereira, Janaina A. M.; Schwaab, Marcio; Dell'Oro, Enrico; Pinto, José Carlos; Monteiro, J.L.F.; Henriques, Cristiane A.

doi:10.1016/j.hydromet.2008.07.009

Cited by 46 publications

(30 citation statements)

References 11 publications

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“…All of the samples at ambient temperature took more-or-less the same amount of time to reach equilibrium, regardless of the hydroxide concentration. This matches the finding of a 2009 study (Pereira et al 2009), which found that hydroxide concentration over the range of 5 to 9 wt% NaOH had no significant effect on the rate of gibbsite dissolution over the temperature range of 60 to 100 LAB-RPT-13-00011 Rev 0…”

Section: Effect Of Hydroxide Concentrationsupporting

confidence: 89%

“…LAB-RPT-13-00011 Rev 0 Equation 3-2 is similar to, but more empirical than, a model used in a 2009 study ("The kinetics of gibbsite dissolution in NaOH" [Pereira et al 2009]) of gibbsite dissolution rates at 60 to 100 o C. Equation 3-3 is the model that those researchers found provided the best fit to their data. Their lower-case k is described as a kinetic rate constant and is equivalent to parameter b in Equation 3-2.…”

Section: Lab-rpt-13-00011 Revmentioning

confidence: 97%

See 1 more Smart Citation

Effect of Phosphate, Fluoride, and Nitrate on Gibbsite Dissolution Rate and Solubility

Herting¹

2014

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Section: Effect Of Hydroxide Concentrationsupporting

confidence: 89%

Section: Lab-rpt-13-00011 Revmentioning

confidence: 97%

Effect of Phosphate, Fluoride, and Nitrate on Gibbsite Dissolution Rate and Solubility

Herting¹

2014

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“…Therefore, it has a great practical significance to study the dissolution kinetics for identifying the main rate-controlling step and accelerating the dissolution process [6] . Many literatures were focused on the dissolution kinetics of corundum, gibbsite and diaspore using a relatively lower caustic concentration [7][8][9][10][11][12][13][14][15] . However, investigation on dissolution kinetics of corundum in high concentration caustic was not found up to date.…”

Section: Introductionmentioning

confidence: 99%

Corundum dissolution in concentrated sodium hydroxide solution

Wu¹,

Li²,

Shi³

et al. 2016

China Foundry

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Efforts to achieve high performance in turbine engines have been limited by the ceramic materials used in the investment casting of hollow, high pressure turbine engine airfoils. The process requirements for casting temperatures and soaking time are greater than 1,700 ºC and 16 hours, respectively, exceeding the permissible ceramic/molten metal contact time limitation. Generally, the ceramic used for casting cores must be able to serve as the material for the casting mold in the investment casting of nickel based superalloy turbine airfoils (e. g. turbine blades and vanes) with internal air cooling passages.Corundum (α-alumina) has been considered as a candidate for investment casting of hollow, high pressure turbine engine airfoils for its excellent properties, such as high chemical metallurgy stability and creep resistance, which can provide better dimensional tolerance in internal passages of airfoils [1][2] . However, it is very difficult to leach out the core made in α-alumina from the casting. Many methods and apparatus have been employed with leaching solution of potassium Abstract: The corundum (α-alumina) core has been considered as a suitable candidate for investment casting of hollow, high pressure turbine engine airfoils due to its excellent properties. However, the efficiency of removing alumina cores in concentrated caustic solution cannot meet the needs of industrial production. In this paper, the effects of temperature and initial solution concentration on dissolution of α-alumina were studied by the classical weight-loss method. The fractal kinetic model was developed in order to describe α-alumina dissolution, assuming that the nonporous particles shrank during reaction process. The results show that the dissolution rate increases with increasing reaction temperature and initial solution concentration. Especially, the initial solution concentration has a significant influence on α-alumina dissolution rate at a higher reaction temperature. The activation energies decrease with increasing initial solution concentration, and the chemical reaction is the rate-controlling step.

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“…Bayer process includes the high pressure leaching of bauxites in a concentrated sodium hydroxide (caustic) solution at temperatures, ranging from 373 K (100 12 . The main source of aluminum and sodium hydroxide losses during the Bayer process is Sodium aluminosilicate which is precipitated in red mud.…”

Section: Introductionmentioning

confidence: 99%

ANFIS based prediction of the aluminum extraction from boehmite bauxite in the Bayer process

Mihajlović

Obradovic

Živković

2014

Polish Journal of Chemical Technology

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This paper presents the results of nonlinear statistical modeling of the bauxite leaching process, as part of Bayer technology for alumina production. Based on the data, collected during the year 2011 from the industrial production in the alumina factory Birač, Zvornik (Bosnia and Herzegovina), nonlinear statistical modeling of the industrial process was performed. The model was developed as an attempt to defi ne the dependence of the Al 2 O 3 degree of recovery as a function of input parameters of the leaching process: content of Al 2 O 3 , SiO 2 and Fe 2 O 3 in the bauxite, as well as content of Na 2 Ocaustic and Al 2 O 3 in the starting sodium aluminate solution. As the statistical modeling tool, Adaptive Network Based Fuzzy Inference System (ANFIS) was used. The model, defi ned by the ANFIS methodology, expressed a high fi tting level and accordingly can be used for the effi cient prediction of the Al 2 O 3 degree of recovery, as a function of the process inputs under the industrial conditions.

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The kinetics of gibbsite dissolution in NaOH

Cited by 46 publications

References 11 publications

Effect of Phosphate, Fluoride, and Nitrate on Gibbsite Dissolution Rate and Solubility

Effect of Phosphate, Fluoride, and Nitrate on Gibbsite Dissolution Rate and Solubility

Corundum dissolution in concentrated sodium hydroxide solution

ANFIS based prediction of the aluminum extraction from boehmite bauxite in the Bayer process

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