Jennifer Morris

Open Limestone Channels are a passive method of treating acid rock drainage, by allowing acid rock drainage to flow through limestone, initiating a neutralizing chemical reaction. Acid rock drainage is a by product of sulphide minerals oxidizing. Any metals in solution precipitate out and form an armored coating on the limestone, decreasing efficiency. There are many ways to treat acid rock drainage; the focus of this project is open limestone channels. Limestone neutralizes acid by reacting calcite, CaCO₃, with the acid to produce calcium in solution and carbonic acid. Several experiments were performed to try to determine the key parameters which govern the working of an open limestone channel such as dissolution rate, time, pH, mass loss and mineral content. Basic set up included a storage container for the prepared acid rock solution, a catching container for the treated solution to drip into, and the channel. This set up allowed the acid rock drainage solution to drip steadily into the limestone channel, and allowed for ease of measurements. Results showed trends of what influences the dissolution rates. Major influences are the pH of the solution, the time the solution is in contact with the limestone and the concentration of any metals in solution. Future studies in experiments with open limestone channels should try to narrow the focus of the experiments.

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Supervisors: John Hill