Hannebachite- a rare and important Sulphite Term Paper

Hannebachite- a rare and important Sulphite - Term Paper Example In fact Hannebachite among the two most important naturally occurring sulfites, the other being Orschallite (Ca3(SO3)2(SO4).12H2O). Hannebachite, Orschallite, scotlandite (PbSO3) and gravegliaite are rare sulphite minerals that come under the class of Sulphites. The name â€Å"hannebachite† has been derived from the place it was first discovered in i.e.at Hannerbacherly, near Hannebach, West Germany. Sulfite groups have the generalized formula Am[SO3]pZq ·xH2O and AmBn[SO3]pZq ·xH2O, where A and B both are cations and Z represent anion. The most commonly occurring cations groups binding includes Na+, K+, Cu2+, Mg2+, Al3+, Ca2+, Pb2+, and Ba2+. The molecular arrangement of sulphite is such that the sulfur molecule is at the apex of the pyramid thereby making sulfites really unstable. This is the reason why sulphite minerals are rarely found in nature. Hannebachite is an important component of fixated scrubber sludge. The structure of Hannebachite has several applications an d forms the basis of further investigation since the applications of the mineral are yet to be determined and hence immense scope of research lies in this area. Introduction Hannebachite received its IMA status in 1983 following which the first ever publication on it was produced by G.Hentschel, E.Tillmanns and W. Hofmeister in 1985; however, the first person to detect the presence of this mineral was P.Orschall who was also the discoverer of Orschallite mineral. He found these minerals in a place named Hannerbacherly in West Germany. In nature Hannebachite is mostly found along with another sulfite mineral called Orschallite. Other minerals found in the porous cavities of quaternary melilite nepheline leucitite are clinopyroxene, apatite and phillipsite COMPOSITION The mineral –hannebachite, gained importance owing to commercial research on sulfite rich scrubber materials. Studies have shown that sulfite rich scrubber material extracted from power plants were rich in Hanneba chite crystallites (Malhotra,2010). In nature Hannebachite is found as sharp, almost clear crystalline structure. The composition of the mineral is SO2 49.60%,CaO 43.42%, H2O 6.98% which corresponds to its molecular formula (Anthony et al,2000).Sulfites in nature are highly unstable owing to the pyramidal structure where the sulfur is seen at the apex while the oxygen sits on the other corners of the arrangement; thereby these unstable products change into sulfates. However, CaSO4.0.5H2O can substitute into the CaSO3.0.5H2O structure up to a mole fraction of at least 0.12 (Jones et al., 1977). Structure of Hannebachite It is already known that the chemical composition of the mineral includes carbon, hydrogen sulfur and oxygen. The molecular weight is about 258.30gm. Hannebachite is orthorhombic. Its space group is Pbna (2m/2m/2m). Extensive studies have been done to determine the exact structure of the mineral. Powder diffraction was conducted to calculate the single crystal profile (figure 3). The optical class of the mineral was seen to be biaxial. It was recorded that a= 6.46A, b= 7.765A and c=10.650A which means that in the orthorhombic crystal system of hannebachite alpha=90 °, beta= 90 ° and gamma=90 °. The J-mol structure gives a clear interpretation of this structure (Figure:3). Spectroscopic studies conducted brought forward a clear idea of the bonding between the atoms present (Figure 1). The structure of hannebachite mineral was studied through Raman Spectroscopy by Frost and Keefe. The sample for hannebachite was supplied by Mineralogical Research Company who sourced in from the Hannebacher Ley volcano in Germany. The bands are observed at