Effect Of Iron Content On The Ash Slag Mineral Composition In High Sulfur Coal

Choosing LZ as the research object at first, CaSO4 was added into LZ to study the migration of sulfur in coal which to provide the theoretical foundation of sulfur element effect the transformation of iron minerals. Meanwhile SiO2, Al2O3 and Fe2O3 were added into ZX without changing the ratio of SiO2/Al2O3, the ash fusion temperatures, mineral components in coal and microstructure of the slag under different iron content were measured by 5E-ⅡF type instrument, X-ray diffractometer and scanning electron microscope combined with energy dispersive X-ray (SEM-EDX). At the same time to observe the transformation of iron-bearing minerals influenced by sulfur. The equilibrium composition of the slag was calculated by thermodynamic software. According to the experimental results, the following conclusions were summed up:(1) The ash fusion temperature of LZ coal adding with calcium base flux was reduced, and the reduction of LZ coal adding with CaSO4 was more obviously. CaS was decomposed by CaSO4, it influenced the ash fusion temperature. Combining with the results of SEM-EDX, sulfur elements in slag not completly out in gas form after adding CaSO4. Sulfur and iron in coal reacted into low temperature melt.(2) The ash fusion temperature has fluctuation after changing the content of iron in high sulfur coal ZX. Comparing with the mineral composition, the result shows that when the content of iron is less than raw coal (WFe2O3<11.76%), the influence of calcium ion in the mineral composition is greater than iron ion. Anorthite and FeS exit in ash high-temperature minerals. The influence of iron ion in the mineral composition is greater than calcium ion when the content of iron is more than raw coal(WFe2O3≥11.76%), the molecular structure of anorthite was broken by iron ion and iron calcium aluminosilicate was created, mullite, Fe and FeS exit in ash high-temperature minerals.(3) Comparing with microstructure of the slag in different iron content, after reaching the flowing temperature, the base mineral of slag is mainly concluded calcium aluminosilicate minerals. A small amount of FeS and FeO were founded when WFe2O3=8.82%. With the increase of iron content, the base mineral of slag is melting, concluded lots of iron minerals especially melting iron and iron aluminosilicate.(4) From thermodynamic software simulation results show that higher iron content of the slag will inhibit the formation of mullite, the less content of mullite, and accelerate the quartz, anorthite, mullite mineral eutectic to generate calcium iron silicate temperature vitreous, shorten the liquid phase formation surge capacity in the temperature interval.(5) Sulfur in coal has a great influence on transformation of iron minerals, sulfur ion and iron ion would react into FeS and (Fe-O-S)melt.