Grants and Contracts Details
Description
Project Title:
Prevention of Acid Mine Drainage from its Source: Inhibition of Pyrite Oxidation using Humate
Rich Food Waste Compost
Principal Investigator: Dr. Xinbo Yang
PROJECT ABSTRACT
The overall objective of this project is to develop and examine a novel process proposed to
prevent the acid mine drainage formation from its source by inhibiting pyrite oxidation using
environmentally benign food waste compost material.
The treatment of acid mine drainage (AMD) is one of the biggest problems in mining
environmental remediation processes due to its large quantity, long formation time, unpredicted
reactions and noncentralized locations. The typical method of treating AMD prior to discharge
from a mine site is to add a caustic solution or pass-through alkaline rock beds to induce
precipitation of the dissolved metal ions and neutralization of the acidity. Some innovative
methods of treatments have been developed in the past decades including coagulation
sedimentation, chemically oxidation, biological passive treatment, nanoparticle adsorptions, and
membrane technology etc. However, due to the high costs of these methods and the possible
secondary pollution problem, the traditional neutralization treatment of AMD is still widely used.
Once the acidified water generated and the metal ions was immobilized into the solution, the
treatment of AMD is a prolonged process and must be continuing for decades. An effective solution
to the AMD problem is to cure the root cause instead of curing the symptom. It is necessary to
change the way of thinking and develop technologies for the source to inhibit or even eliminate
the formation of acidic mine water.
The root cause of acidic mine water is the oxidation of pyrite in the mine tailings that
exposed to air during mining through a series of biotic and abiotic process. The key factors that
resulted in the pyrite oxidation in the mine tailing is water content, oxygen (air) content, and the
microbial activities (mainly Acidthiobacillus ferrooxidans). Some of the source treatment
technology include oxygen depleted covering, bactericide, surface passivation treatment, and
neutralization of mine tailings, etc. Except for the covering technique, all the other methods
involve spraying and mixing of chemicals are environmentally harmful. The proposer intends to
apply waste food compost material as a filler in the pyrite containing mine tailings to inhibit the
pyrite oxidation process. The compost material contains humate subtract that can react with pyrite
and create a passivation layer on the particle surface. Study shows that the adsorption of humic
acid on pyrite surface is almost irreversible, and the pyrite electrochemical activity can be
practically inhibited. The compost material also provides a barrier to water and air as the soil
contains numerous microbial organisms. The scope of work proposed in this study will include
construction of several leaching columns for evaluating the acid generation capability of mine
tailing material at various aeration rate, intermittent water flowrate, and temperature to simulate
the seasonal mine tailing storage conditions. A control column will be established to first evaluate
the key rate controlling steps in pyrite oxidation and identify the key steps to inhibit the oxidation
reaction and the breeding of bacteria. The degree of bacteria growth will be tested with an oxidation
simulation test. The results of the control column will also serve to develop a prediction tool to
determine the toxic elements release of AMD with different geographic properties. As one of the
tasks a few of selected environmentally benign bactericide will be evaluated to prevent the pyrite
oxidation reaction through sterilization of the bacteria.
Status | Finished |
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Effective start/end date | 2/1/22 → 6/30/22 |
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