High-Temperature Reaction of Kaolin with Sodium Hydrogen Sulfate
24 May 2005-Industrial & Engineering Chemistry Research (American Chemical Society)-Vol. 44, Iss: 13, pp 4495-4500
TL;DR: In this article, a procedure was described in which kaolin and NaHSO4 were heated in a furnace at temperatures between 200 and 1000 °C. Parameters studied were the reaction temperature and time, proton to alumina molar ratio, calcination temperature, and reaction atmosphere.
Abstract: A procedure is described in which kaolin and NaHSO4 are heated in a furnace at temperatures between 200 and 1000 °C. Parameters studied were the reaction temperature and time, proton to alumina molar ratio, calcination temperature and time, and reaction atmosphere. The Al reaction yield grew until reaching a maximum at a reaction temperature of 700 °C and decreasing sharply beyond this temperature. The Ti reaction yield values were lower than the Al reaction yield, showing a maximum at 400 °C and decreasing smoothly as the reaction temperature was increased. The Fe reaction yield showed a maximum in the same range of reaction temperature as Al. Precalcination of kaolin produced only slight increases in reaction yields. Brunauer−Emmett−Teller (BET) surface area tests indicated an increase of the BET surface area for short reaction times, reaching values above 100 m2/g. Products of the reaction were Na3Al(SO4)3, NaAl(SO4)2, NaAl(SO4)2·xH2O (x = 6 and 12), Na3H(SO4)2, Al2O3, Na2SO4, and mullite.
Citations
More filters
TL;DR: In this article, dealuminated samples were introduced into a sodium-potassium hydroxide solution under reaction conditions for the gel formation step in zeolite X synthesis using kaolin plus additional Si.
46 citations
TL;DR: The results indicated that NaHSO4 facilitated the decomposition of the polymeric phases and significantly improved the alumina extraction in coal fly ash (CFA) as mentioned in this paper, which is a good way to enhance its value-added utilization.
Abstract: The extraction of alumina from coal fly ash (CFA) is a good way to enhance its value-added utilization The presence of inert matter with a high degree of polymerization, such as mullite and other aluminosilicates, greatly restricts the reactivity of CFA Thus, the CFA needs to be activated before use Thermal activation by calcination with added sodium hydrogen sulfate (NaHSO4) was carried out in this study The calcination products were characterized by means of X-ray diffraction, thermal gravimetric and differential scanning calorimetric analysis, and scanning electron microscopy to assess the effects of the additive, calcining temperature, and calcining time on the products The results indicated that NaHSO4 facilitated the decomposition of the polymeric phases and significantly improved the alumina extraction Alumina in CFA was transformed into soluble Na3Al(SO4)3 When CFA was mixed with sodium hydrogen sulfate at a NaHSO4/Al2O3 molar ratio of 6, the alumina extraction reached 90 % at 500 °C after 2 h
33 citations
Cites methods from "High-Temperature Reaction of Kaolin..."
...[28] extracted alumina from kaolin by a sodium hydrogen sulfate sintering process....
[...]
TL;DR: In this paper, a template-free strategy was proposed and demonstrated to process natural kaolin into mesoporous silica with enlarged specific surface area (SBET), which showed favorable adsorption ability towards methylene blue.
17 citations
TL;DR: In this article, a facile hydrometallurgical method was proposed for high-efficiency extraction of aluminum at low activation temperature from low-grade kaolin involving sulfuric acid assisted activation followed by water leaching.
16 citations
TL;DR: These widely-used industrial standards should be quantitatively characterized morphologically, compositionally, and structurally on the pharmaceutical grade kaolinites and reported to the relevant regulatory agencies.
Abstract: The physical and chemical characteristics of kaolinite (kaolin) may be variable, and minor amounts of other clay minerals, nonclay minerals, and other impurities may affect the properties of kaolinites. Thus specific technical properties of pharmaceutical grade kaolinites become very important because these clays are used in medical applications, e.g., as pharmaceutical excipients, and will be consumed by humans. Seven pharmaceutical grade kaolinite specimens were used in this study: K1004, KA105, 2242-01, K2-500, Acros, Acros-mono, and KX0007-1. In addition, two kaolinites from the Clay Minerals Society Source Clays, KGa-1b and KGa-2, were used for comparison purposes. The Acros-mono and 2242-01 kaolinites contained minor amounts of illite, which was demonstrated both compositionally and structurally by using inductively coupled plasma spectroscopy and powder X-ray diffraction. The KX0007-1 kaolinite powder was found to be heavily contaminated with quartz, cristobalite, and alunite. Crystal structure computations also showed excess Si in its tetrahedral site, and the mineral no longer has the typical kaolinite crystal structure. These widely-used industrial standards should be quantitatively characterized morphologically, compositionally, and structurally. Results of the mineralogical characteristics should be clearly labeled on the pharmaceutical grade kaolinites and reported to the relevant regulatory agencies.
14 citations
References
More filters
24,580 citations
TL;DR: A matrix-flushing method for quantitative multicomponent analysis by X-ray diffraction is reported in this article, which is simpler and faster than, yet as reliable as, the conventional internal-standard method.
Abstract: A matrix-flushing method for quantitative multicomponent analysis by X-ray diffraction is reported. It is simpler and faster than, yet as reliable as, the conventional internal-standard method. In this new method, the calibration-curve procedure is shunted; a more fundamental `matrix-flushing' concept is introduced. The matrix-flushing theory gives an exact relationship between intensity and concentration free from matrix effect. Contrary to most theoretical methods the working equation is very simple, no complicated calculations are involved. The matrix-flushing theory and the analytical procedure are presented. Eight illustrative examples are drawn to demonstrate how this theory is applied to multicomponent analysis and amorphous-content determination. A novel `auto-flushing' phenomenon of binary systems was observed which appears to make the analysis of any binary system a simple matter.
1,112 citations
TL;DR: In this paper, the authors measured the relative degree of crystal perfection among 144 samples of Coastal Plain kaolin and showed that the deposits are nonhomogeneous with respect to crystallinity and that the hard and soft types can be distinguished at the 0.95 probability level by an analysis of variance.
Abstract: Quantitative measurement of the relative degree of crystal perfection among 144 samples of Coastal Plain kaolin shows that the deposits are nonhomogeneous with respect to crystallinity and that the hard and soft types can be distinguished at the 0.95 probability level by an analysis of variance. The nonhomogeneity of the deposits and the distinction between the hard and soft types agrees with the results obtained for other properties not reported here. Although on the basis of pulverizing ease there may be a single population with hard and soft end members, in terms of origin the evidence indicates the existence of two distinct clay populations.
443 citations
TL;DR: In this article, the substitution of irori(III) in the octahedral (Al) sites was shown to be possible in the case of iron oxides in the kaolinite lattice.
Abstract: KAOLINITE often occurs in admixture with other minerals (for example, micas and iron oxides) in which iron is a legitimate constituent. Because of the difficulties of detection and separation, it has always been doubtful whether iron actually substitutes in the kaolinite lattice. We provide here evidence for substitution of irori(III) in the octahedral (Al) sites.
75 citations
TL;DR: Titanium in TiO2 minerals was differentiated from that isomorphously substituted into minerals by the use of dihydrogen hexafluorotitanate (hydrofluotitanic acid, H2TiF6) as discussed by the authors.
Abstract: Titanium in TiO2 minerals was differentiated from that isomorphously substituted into minerals by the use of dihydrogen hexafluorotitanate (hydrofluotitanic acid, H2TiF6), which selectively dissolved minerals containing substituted Ti4+, leaving free crystalline TiO2 minerals in the residue. Titanium analyses on the original samples and the residues remaining after H2TiF6 treatment, by both wet chemical (Tiron) and neutron activation methods, indicated that an average of 86 per cent of the titanium in seven kaolinite samples was present in the residual TiO2 form (largely anatase), whereas only 28 per cent in two bentonites was present in the TiO2 form. Residual Ti accounted for 100 per cent of the Ti in synthetic anatase and for 92 per cent of the Ti in coarse clay sized rutile, the latter value suggesting that about 8 per cent amorphous TiO2 was removed from the mechanically dry ground rutile by the H2TiF6 reagent. The Ti present as residual TiO2 in a variety of other samples ranged from 0 to 100 per cent.
69 citations