Neutralization of Acid Mine Drainage with Calcium Hydroxide in Sand Packed Bed Contactor

Abstract

This study investigates the neutralization of acid mine drainage using calcium hydroxide in a sand packed bed contactor. The research aims to evaluate the effectiveness of this method by analyzing the relationship between the molar flow rate of Ca(OH)₂ and the resulting pH increase in the treated water. Nine experiments were conducted, utilizing sulfuric acid (pH 1) as the feed with molar flow rates ranging from 0,0015 to 0,0033 mole/s. The acid was neutralized with calcium hydroxide (pH 12-13) at flow rates between 0,002 and 0,004 mole/s. The pH of the output water product ranged from 4 to 7. Results indicate a direct correlation between the molar flow rate of Ca(OH)₂ and the pH increase in the treated water. However, variations in the acid-base molar ratio showed less significant effects on the pH increase. The findings suggest that utilizing Ca(OH)₂ in a sand packed bed contactor is a practical and effective approach for acid mine drainage neutralization. Further research could explore the application of CaO as a heap contactor to enhance treatment efficiency in mining environments.