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Controlling the Rate of Acid Loss from Strip Mine Spoil
Author(s) -
Pionke H. B.,
Rogowski A. S.,
De Angelis R. J.
Publication year - 1980
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1980.00472425000900040031x
Subject(s) - pyrite , diffusion , particle (ecology) , volume (thermodynamics) , chemistry , particle size , radius , mineralogy , analytical chemistry (journal) , environmental chemistry , geology , thermodynamics , physics , oceanography , computer security , computer science
The objective was to identify and compare processes that potentially dominate acid production and loss at the spoil particle scale. This information is presently lacking, but is critical for correctly hypothesizing and testing the effects of alternative management (reclamation) on ground water quality. The effectiveness of selected diffusion and kinetic processes for controlling the rate of acid product loss from the spoil particle were compared. Initially, the acid production rate in unweathered fresh spoil exposed to 20% O 2 appears controlled by the pyrite oxidation rate. However, the control of acid product loss rates from a partially weathered spoil particle decreased in the order: acid product diffusion > O 2 diffusion > pyrite oxidation. The acid product contributing zone of the assumed‐cylindrical spoil particle was calculated using experimental and published data. For the acid products, i.e., common SO 4 salts, the acid product contributing zone was 0.022‐cm depth/0.25‐cm particle radius or 17% of total particle volume. For O 2 , the zone was 0.06‐cm depth/0.25‐cm particle radius or 42% of total particle volume. Under these experimental conditions, the remaining particle volume was essentially noncontributing. Based on these data, increasing the particle radius substantially reduced the contributing volume. Experimental results showed that acid‐product generation over the long term averaged 0.16 mg SO 4 /g pyrite per hour for the air‐incubated system and 0.018 mg SO 4 /g pyrite per hour for the O 2 ‐free (N 2 ) incubated system.