Anoxic Limestone Drain (ALD)
nounPronunciation: /ænˈɒksɪk ˈlɪmstəʊn dreɪn/
A passive treatment structure filled with limestone that removes acidity and metals from mine drainage under anaerobic conditions. The limestone dissolves in the acidic water, raising pH and precipitating dissolved metals while maintaining anaerobic conditions that prevent further oxidation.
Plain English
A limestone-filled drain that neutralizes acidic mine water without oxygen by dissolving limestone and removing metals.
Etymology & History
Usage
"The anoxic limestone drain successfully treated acid mine drainage flowing from the underground coal mine."
Style guide notes: Clarify oxygen conditions when discussing limestone drain types; anoxic and aerobic produce different chemical outcomes.
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Contrasted with
Related Terms
Frequently Asked Questions
How does an anoxic limestone drain work?
Acidic water flows through limestone under anaerobic conditions; limestone dissolves raising pH while metals precipitate and settle.
When is an ALD appropriate for mine reclamation?
ALDs work best for moderate to high-flow, acidic drainage with low dissolved oxygen levels and manageable metal concentrations.
Why Test Candidates on This?
ALD design calculations and geochemical principles are tested in advanced mine water treatment certification programs.
Required skill level: Senior