Calcium carbonate scaling under alkaline conditions – Case studies and hydrochemical modelling

摘要: Abstract Calcium carbonate scaling poses highly challenging tasks for its prediction and preventative action. Here an elemental, isotopic modelling approach was used to decipher the evolution of alkaline tunnel drainage solutions sinter formation mechanisms 3 sites in Austria. Drainage originate from local groundwater form their characteristic chemical composition by interaction with shotcrete/concrete. This is indicated a positive correlation dissolved K + pH (up 12.3), decrease aqueous Mg 2+ brucite (pH > 10.5). Variability Ca DIC strongly attributed portlandite dissolution, calcite precipitation CO 2 exchange atmosphere, where 13 C / 12 18 O 16 signatures can be traced back source carbonate. The internal P CO2 value reliable proxy evaluate whether uptake results increase or degree saturation threshold 10 −6.15  atm at 25 °C (pH ≈ 11). Precipitation rates are highest pH ≈ 10. Mixing groundwater-like strong has considered as crucial factor evaluating apparent capacities.