Grants and Contracts Details
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.
|Effective start/end date||2/1/22 → 6/30/22|
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