Mechanism of formation of forsterite and enstatite from serpentine

Brindley, G. W.; Hayami, Ryozo

doi:10.1180/minmag.1965.035.269.21

Cited by 58 publications

(40 citation statements)

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“…As well, decreasing the particle size yields an increase of the rate of dehydration as well as in the peak height of the exotherm at 8 10°C. The particle size has already been illustrated and discussed (22,26,27). With a small-size particle, the water is easily expelled and the dehydroxylation occurs rapidly.…”

Section: (B) Characteristic Properties Of Chrysotile-1 and -2mentioning

confidence: 97%

Differences between adsorption properties of two Rhodesian chrysotile samples. Relation with the DTA features introduced by leaching and grinding

Suquet¹

1989

Can. J. Chem.

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H~L~N ESUQUET. Can. J . Chem. 67, 202 (1989). Substantial differences are founded between the absorption properties of two Rhodesian chrysotile samples (-1 and -2), which are, in most chemical and structural aspects, highly similar. The phenanthrene and C 0 2 amounts adsorbed are much less important on chrysotile-2 than on chrysotile-1. This indicates that chrysotile-2 has fewer basic surface sites. DTA and XRD results show that dry grinding and leaching produce a breakdown of the chrysotile structure, yield amorphous silica, and lower the temperature of the dehydroxylation peak. The dehydroxylation peaks of chrysotile-1 and -2 are really doublets. As the low-temperature component of the dehydroxylation peak is greater in chrysotile-2 than in chrysotile-1, the chrysotile-2 contains more ground and (or) leached fibers than chrysotile-l and consequently shows weaker absorption properties.Key words: chrysotile, leaching, phenanthrene adsorption.H~L~N E SUQUET. Can. J. Chem. 67, 202 (1989). On a observe des diffirences importantes dans les propriCtCs d'absorption de deux Cchantillons de chrysotile RhodCsiens (-1 et -2) qui sont, par leurs aspects chimiques et structuraux, trks semblables. Les quantitts de phknanthrkne et de COz qui sont adsorbtes sur la chrysotile-2 sont beaucoup plus faibles que celles adsorbCes sur la chrysotile-1. Ces donnkes indiquent que la chrysotile-2 possede moins de sites basiques. Les rCsultats obtenus par ATD et par DRX montrent que le broyage a sec ainsi que la lixiviation provoquent un effondrement de la structure de la chrysotile qui conduit a de la silice amorphe et a un abaissement de la tempirature du pic de dkhydroxylation. Les pics de dkhydroxylation des chrysotiles-1 et -2 sont en fait des doublets. Comme la composante basse tempCrature du pic de dChydroxylation est plus grande dans la chrysotile-2 que dans la chrysotile-1, on en conclut que la chrysotile-2 contient plus de fibres broyCes et (ou) lixiviCes que la chrysotile-1 et que, en conskquence, elle fait preuve de propriktCs d'adsorption plus faibles.

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Section: (B) Characteristic Properties Of Chrysotile-1 and -2mentioning

confidence: 97%

Differences between adsorption properties of two Rhodesian chrysotile samples. Relation with the DTA features introduced by leaching and grinding

Suquet¹

1989

Can. J. Chem.

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“…According to the synthesis route via solid state reactions between MgO and SiO 2 powder mixtures, 10) the orthosilicate phase (Forsterite) is formed at the silica side of the MgO/SiO 2 interface. Thereby, MgO diffuses into the silica phase generating a layer of MgSiO 3 which is amorphous at first and crystallizes subsequently [s. Eq.…”

Section: Resultsmentioning

confidence: 99%

“…10) Due to the high reactivity of the PHPS precursor in combination with the grinded MgO, an almost full conversion to forsterite was achieved at a maximum temperature of 1100°C, whereas no reaction was observed at 900°C (see Fig. 2).…”

Section: Siàh þmentioning

confidence: 99%

Formation of Mg-silicates by reaction of perhydropolysilazane with MgO during pyrolysis in air

Seifert

Leite

Motz

2016

J. Ceram. Soc. Japan

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The present study deals with the synthesis of Mg 2 SiO 4 (Forsterite) applying the route of polymer derived ceramics (PDCs). The liquid, inorganic perhydropolysilazane (PHPS) was used because it is very reactive during pyrolysis in air and forms amorphous SiNO ceramic containing a tremendous amount of SiO 2 . Both facts are crucial for the reaction with MgO in order to synthesize Mg-silicates. The results of this study demonstrate, that the Mg-orthosilicate phase is formed at the MgO/SiNO interface via solid state reaction at comparably low temperatures of 1100°C during pyrolysis in air for 2 h. Furthermore the high reactivity of the polysilazane leads to an almost full conversion of the MgO to Mg 2 SiO 4 under the used conditions.

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“…(Skinner et al, 1988;Virta, 2003). 그 결과 백석면은 사면체판 방향으로 휘어져 층 이 연장됨에 따라 실린더 형태로 말리게 되며, 섬유의 중심이 비어있는 튜브 형태인 중공관(hollow tube) 구 조를 가지는 섬유상의 광물로 산출된다 (Yada, 1967(Yada, , 1971 Ball and Taylor (1963), Brindley andHayami (1965), andMartin (1977). Table 1.…”

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“…Table 1. Previously proposed experimental and analytical methods of chrysotile, and its reaction temperatures by dehydroxylation according to Ball and Taylor (1963), Brindley and Hayami (1965) and Martin (1977) Ball and Taylor (1963) Brindley and Hayami (1965) Martin ( (Fig. 7).…”

mentioning

confidence: 99%

Characterization of Mineralogical Changes of Chrysotile and its Thermal Decomposition by Heat Treatment

Jeong¹,

Moon²,

Roh³

2016

Economic and Environmental Geology

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Chrysotile is a 1:1 sheet silicate mineral belonging to serpentine group. It has been highlighted studies because of uses, shapes and structural characteristics of the fibrous chrysotile. However, it was designated as Class 1 carcinogen, so high attentions were being placed on detoxification studies of chrysotile. The objectives of this study were to investigate changes of mineralogical characteristics of chrysotile and to suggest detoxification mechanism of chrysotile by thermal decomposition. Samples for this study were obtained from LAB Chrysotile mine in Canada. The samples were heated in air in the range of 600 to 1,300 o C. Changes of mineralogical characteristics such as crystal structure, shape, and chemical composition of the chrysotile fibers were examined by TG-DTA, XRD, FT-IR, TEM-EDS and SEM-EDS analyses. As a result of thermal decomposition, the fibrous chrysotile having hollow tube structure was dehydroxylated at 600-650 o C and transformed to disordered chrysotile by removal of OH at the octahedral sheet (MgOH) (Dehydroxylation 1). Upon increasing temperature, it was transformed to forsterite (Mg 2 SiO 4 ) at 820 o C by rearrangement of Mg, Si and O (Dehydroxylation 2). In addition, crystal structure of forsterite had begun to transform at 800 o C, and gradually grown 3-dimensionally to enstatite (MgSiO 3 ) by recrystallization after the heating above 1,100 o C. And then finally transformed to spherical minerals. This study showed chrysotile structure was collapsed about 600-700 o C by dehydroxylation. And then the fibrous chrysotile was transformed to forsterite and enstatite, as non-hazardous minerals. Therefore, this study indicates heat treatment can be used to detoxification of chrysotile.

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Mechanism of formation of forsterite and enstatite from serpentine

Cited by 58 publications

References 1 publication

Differences between adsorption properties of two Rhodesian chrysotile samples. Relation with the DTA features introduced by leaching and grinding

Differences between adsorption properties of two Rhodesian chrysotile samples. Relation with the DTA features introduced by leaching and grinding

Formation of Mg-silicates by reaction of perhydropolysilazane with MgO during pyrolysis in air

Characterization of Mineralogical Changes of Chrysotile and its Thermal Decomposition by Heat Treatment

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