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Acid neutralization within limestone sand reactors receiving coal mine drainage [An article from: Environmental Pollution]
Description
This digital document is a journal article from Environmental Pollution, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Pulsed bed treatment of acid mine drainage (AMD) uses CO"2 to accelerate limestone dissolution and intermittent fluidization to abrade and carry away metal hydrolysis products. Tests conducted with a prototype of 60L/min capacity showed effective removal of H^+ acidity over the range 196-584mg/L (CaCO"3) while concurrently generating surplus acid neutralization capacity. Effluent alkalinity (mg/L CaCO"3) rose with increases in CO"2 (DC, mg/L) according to the model Alkalinity=31.22+2.97(DC)^0^.^5, where DC was varied from 11-726mg/L. Altering fluidization and contraction periods from 30s/30s to 10s/50s did not influence alkalinity but did increase energy dissipation and bed expansion ratios. Field trials with three AMD sources demonstrated the process is capable of raising AMD pH above that required for hydrolysis and precipitation of Fe^3^+ and Al^3^+ but not Fe^2^+ and Mn^2^+. Numerical modeling showed CO"2 requirements are reduced as AMD acidity increases and when DC is recycled from system effluent.
Description:
Pulsed bed treatment of acid mine drainage (AMD) uses CO"2 to accelerate limestone dissolution and intermittent fluidization to abrade and carry away metal hydrolysis products. Tests conducted with a prototype of 60L/min capacity showed effective removal of H^+ acidity over the range 196-584mg/L (CaCO"3) while concurrently generating surplus acid neutralization capacity. Effluent alkalinity (mg/L CaCO"3) rose with increases in CO"2 (DC, mg/L) according to the model Alkalinity=31.22+2.97(DC)^0^.^5, where DC was varied from 11-726mg/L. Altering fluidization and contraction periods from 30s/30s to 10s/50s did not influence alkalinity but did increase energy dissipation and bed expansion ratios. Field trials with three AMD sources demonstrated the process is capable of raising AMD pH above that required for hydrolysis and precipitation of Fe^3^+ and Al^3^+ but not Fe^2^+ and Mn^2^+. Numerical modeling showed CO"2 requirements are reduced as AMD acidity increases and when DC is recycled from system effluent.
