brownmillerite


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brownmillerite

A mineral compound occurring in portland cement and high-alumina cement; consists of an oxide of calcium, aluminum, and iron.
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Peaks possible corresponding to: molibdite Mo[O.sub.3] (COD: 96-101-1074), hematite [Fe.sub.2][O.sub.3] (COD: 96-900-0140), calcium ferrite Ca[Fe.sub.3][O.sup.5] (COD: 96-901-3960), powellite CaMo[O.sub.4] (COD: 96-900-9634), brownmillerite [Ca.sub.2][Fe.sub.2][O.sub.5] (COD: 96-900-4372), lime CaO (COD: 96-900-6742), magnetite [Fe.sub.3][O.sub.4] (COD: 96-900-2333), srebrodolskite [Ca.sub.2][Fe.sub.2][O.sub.5] (COD: 96-900-3470), goethite Fe[O.sub.2] (COD: 96901-6060), schwertmannite [Fe.sub.8][O.sub.17] (COD: 96-901-5186) and banfordite Fe[Mo.sub.2][O.sub.10] (COD: 96-900-1903) were observed for these catalytic precursors.
As it can be seen, as the calcination temperature increased, the hematite phase is also increased but the brownmillerite phase is diminished.
In this notation, alite (tricalcium silicate) [(CaO)3Si[O.sub.2]], belite (dicalcium silicate) [[(CaO).sub.2]Si[O.sub.2]], celite (tricalcium aluminate) [[Ca.sub.3][Al.sub.2][O.sub.6] = 3CaO x [Al.sub.2][O.sub.3]], and brownmillerite (tetracalcium aluminoferrite) [[Ca.sub.4][Al.sub.2][Fe.sub.2][O.sub.10] = 4CaO x [Al.sub.2][O.sub.3] x [Fe.sup.2][O.sub.3]] are represented by [C.sub.3]S, [C.sub.2]S, [C.sub.3]A, and [C.sub.3]AF, respectively.
Compound Formula Notation wt.% Celite [Ca.sub.3] [C.sub.3]A 10 (tricalcium [Al.sub.2] [O.sub.6] aluminate) [3CaO x [Al.sub.2] [O.sub.3]] Brownmillerite [Ca.sub.4] [C.sub.4]AF 8 (tetracalcium [Al.sub.2] aluminoferrite) [Fe.sub.2] [O.sub.10] [4CaO x [Al.sub.2] [O.sub.3] x [Fe.sub.2] [O.sub.3]] Belite (dicalcium [Ca.sub.2] [C.sub.2]S 20 silicate) Si[O.sub.4] [2CaO x Si[O.sub.2]] Alite (tricalcium [Ca.sub.3]Si [C.sub.3]S 55 silicate) [O.sub.5] [3CaO x Si[O.sub.2]] Sodium oxide [Na.sub.2]O N [less than or equal to] 2 Potassium oxide [K.sub.2]O K Gypsum (calcium CaS[O.sub.4] x CS[H.sub.2] 5 sulphate 2[H.sub.2]O [CaO x dihydrate) S[O.sub.3] x 2[H.sub.2]O] Adapted from [2]; http://www.engr.psu.edu/ce/courses/ ce584/concrete/library/construction/curing/ Composition%20of%20cement.htm.
Analysis of water-cooled slag (average sample) preparation identified wustite (FeO), dicalcium and tricalcium silicates (2CaO.Si[O.sub.2], [C.sub.2]S i 3CaO.Si[O.sub.2], [C.sub.3]S), brownmillerite [([Ca.sub.2] (Al, Fe).sub.2][O.sub.5], [C.sub.4]AF) and mayenite (12CaO.7[Al.sub.2][O.sub.3], [C.sub.12][A.sub.7]), as showed in Fig.
The most characteristic minerals are the following: wustite (FeO), which is well crystallized into round and oval-shaped particles, similarly crystallized lamellar larnite with some allite ([C.sub.2]S + [C.sub.3]S), both of which are embedded in a microcrystalline matrix of brownmillerite ([C.sub.4]AF), and mayenite ([C.sub.12][A.sub.14][O.sub.33]).
In order examine this, a series of mixtures containing the synthesized solid solution material brownmillerite, [Ca.sub.2][(Al,Fe).sub.2][O.sub.5], was to be made.
His index of species lists such less-than-common minerals as barytolam-prophyllite, brownmillerite, cuprorivaite, hannebachite, jasmundite, tangeite, and (ahem) willhendersonite.
E: ettringite; F: Friedel's salt; M: monosulphate; P: portlandite; B: Brownmillerite; CSH: calcium-silicate-hydrate.
Calcium aluminium iron oxide hydroxide [Ca.sub.12][Al.sub.13.8][Fe.sub.0.14][O.sub.32][(OH).sub.2]/11CaO x 6.9[Al.sub.2][O.sub.3] x 0.07 [Fe.sub.2][O.sub.3] x Ca[(OH).sub.2], brownmillerite [Ca.sub.2][(Al,Fe).sub.2][O.sub.5] and calcium aluminium iron oxide Ca[Al.sub.8][Fe.sub.4][O.sub.19]/CaO x 4[Al.sub.2][O.sub.3] x 2[Fe.sub.2][O.sub.3] are probable Ca, Fe and Al compounds.
XRD mineralogy (%) Mineral Percentage composition (%) Calcium silicate 40 Laminate 19 Calcium aluminium oxide 16 Brownmillerite 13 Periclase 8 Gypsum 4 TABLE 5: Chemical composition of lime as determined by XRF.
For example, dicalcium and tricalcium silicates (2CaO x Si[O.sub.2], [C.sub.2]S and 3CaO x Si[O.sub.2]), brownmillerite ([Ca.sub.2][(Al,Fe).sub.2][O.sub.5]), wustite (FeO), and mayenite (12CaO x 7[Al.sub.2][O.sub.3]) are the most highly represented mineral phases detected in the earlier published work [11].