Oldhamite (CaS) (9CI) CAS NO.12015-71-3

High temperature interactions among minerals occurring in coal High temperature interactions among minerals occurring in coal. Biggs, Donald L.; …

High temperature interactions among minerals occurring in coal High temperature interactions among minerals occurring in coal. Biggs, Donald L.; Lindsay, Curtis G. (Iowa State Min. Miner. Resour. Res. Inst., Iowa State Univ., Ames, IA 50011, USA). Prepr. Pap. - Am. Chem. Soc., Div. Fuel Chem., 29(4), 84-91 (English) 1984. CODEN: ACFPAI. ISSN: 0569-3772. DOCUMENT TYPE: Journal CA Section: 51 (Fossil Fuels, Derivatives, and Related Products) Section cross-reference(s): 53 Illite [12173-60-3] and montmorillonite [1318-93-0] are similar in structure and differ slightly from kaolinite [1318-74-7] in this regard. The 1st 2 are composed of 2 Si-O layers per octahedral layer contg. Fe, Mg and Al and in kaolinite the ratio of tetrahedral and octahedral layers is 1. In these crystals, thermal modification is easier because the bonds formed between the Al, Fe, and Mg atoms and O are weaker than the Si-O bonds. Clays, therefore are expected to be more reactive than the SiO2 crystals. There is evidence that some glass is formed in the clay mineral domains during thermal treatment and that Fe diffuses into the mass. Further inquiries are in progress to answer these questions. Calcite [13397-26-7] appears largely inert until temp. approaching 600°C in the presence of some of the clay minerals and inert until about 900° in their absence. The cause of this fluxing is not well understood at this time, but investigations are planned to elucidate this behavior. At whatever temp., the reaction obsd. is for the calcite to decomp. to lime (CaO) and CO2. The extent to which CO2 fluxes further reaction is not known, but must be considered as an important step in complete explanation. Like calcite, pyrite [1309-36-0] is quite reactive and its thermal behavior is influenced by the presence of clay minerals. The initial reaction temp. of pyrite alone or in the presence of calcite alone is to produce pyrrhotite [1310-50-5] and at the highest temp., troilite [1317-96-0]. The loss of S is obvious and continues over an appreciable temp. range. The most important reaction products are those of the Fe enrichment of the clay minerals, probably a precursor of the Fe oxide and glass mixts. commonly obsd. in slags and fly-ashes, and the formation of the sulfide of Ca, oldhamite [12015-71-3]. That oldhamite is obsd. in all expts. where calcite and pyrite interact, and that anhydrite is obsd. only where they have reacted in the presence of an O-rich atm. supports the conclusion that oldhamite, formed in the reducing part of a flame, is a necessary precursor to the formation of the sulfate, anhydrite.