Active treatment
This information was largely taken from EPA Region 3 publication A Citizen's Guide to Address Contaminated Coal Mine Drainage, EPA-903-K-97-003.
Active abandoned mine drainage treatment uses strong alkaline chemicals such as lime, caustic soda, ammonia, and calcium oxide to neutralize acid so that metals can be precipitated and removed. Active treatment systems are classified by the chemical used to treat the abandoned mine drainage.
Types of Treatment
There are six chemical reagents that are typically mixed with contaminated mine drainage in active systems. Each chemical has characteristics that make it more or less appropriate for a specific condition. The best choice among the alternatives depends on both technical and economic factors.
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Limestone (calcium carbonate)
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Hydrated Lime (calcium hydroxide)
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Pebble Quick Lime (calcium oxide)
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Soda Ash Briquettes (sodium carbonate)
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Caustic Soda (sodium hydroxide)
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Ammonia (anhydrous ammonia)
Technical and Economic Factors to Consider
Technical factors include the acidity level of the discharge, rate of flow, types and concentration of metals in water, rate and degree of pH increase desired, and the solubility of the chemicals in the water.
Economic factors include cost of the reagents, handling costs (labor, machinery, and equipment) and the number of years that treatment will be needed.
Overview of Abandoned Mine Drainage Treatment with Chemicals Active Treatment Discussion from WVU