The formation of iron hydroxide coatings in an Emscher Marl: inverse reactive transport modeling of reactive surface area

摘要: The possible effects of iron oxide coatings on the reactive surface area calcite in column experiments have been studied and then modeled numerically. A with six compartments separated by teflon filters was packed Emscher Marl (essentially calcite). marl initially mixed corundum as an internal standard. Hydrochloric acid pH 3 percolated through for a given period, after which mineralogical changes were quantified X-ray diffraction ex-situ. Then, re-filled again HCl. This procedure repeated five times. losses gains provided data basis modeling entire experiment transport code TOUGHREACT using kinetic rate law. experimental results showed that during first loss compartment is about 50 % less than determined from theoretical analysis. entrance into higher preferential flow paths (wormholes) observed at boundary between sample cell wall. pattern could also be verified relatively high Peclet low Damkohler numbers, showing strongly advection-dominant system. Apart dissolution, structural Fe2+ released oxidized formed hydroxide (FeOOH) along fluid pathways. Despite specific assumptions such pure model, comparison lab observations instructive. simulated change patterns most are consistent experiments. Some discrepancies noted last compartment, may bring attention to need model improvements.