Open Access Dissertation
In situ mining is a relatively new method that has the potential of recovering a variety of minerals. This process is quickly becoming an alternative to conventional mining techniques that are environmentally unsound. Two problems associated with in situ mining are, the amount of waste water generated by the process (bleed) and the uncontrolled migration of lixiviant outside the production zone (an excursion). The purpose of this study was to determine if in situ mining processes could be monitored and controlled with a Sequential Control and Data Acquisition (SCADA) system. Using programmable logic controllers, a cost-effective SCADA system was designed and implemented in a uranium mine in northwestern Nebraska. The tests on this system's effectiveness to control the mining process yielded extensive data on flow control, waste water generation and excursion monitoring. A t test was used to analyze the flow rates calculated for each individual production well in the wellfield by both the automated system and by locally mounted flow meters. No significant differences were found between the two sets of data, indicating the automated system accurately monitors flow data. The daily percentage of bleed from the mining process was calculated for each of three randomly selected months. The result was 0.4% average daily bleed as compared to the upper limit of 0.5% required by the mining license. To detect excursions, 40 monitor wells were installed around the perimeter of the wellfield and above the ore bearing aquifer. Hundreds of biweekly samples were taken from these wells during the three years the mining unit was in operation. These samples were analyzed by a laboratory in Casper, Wyoming for the excursion indicators chloride, sodium, sulfate, alkalinity, and conductivity. None of the samples taken had chemical parameters high enough to declare an excursion. The findings of this study support the use of a Sequential Control and Data Acquisition system to monitor and control in situ mining processes. The SCADA system, as implemented in this investigation, yields accurate data through a cost effective method that can be used to recover uranium while controlling excursions and limiting the waste water generated by the process.
Year of Submission
Department of Industrial Technology
Rex W. Pershing, Advisor
1 PDF file (vii, 109 pages)
©1994 Jimmy W. Stokey
Stokey, Jimmy W., "An analysis of the use of programmable controllers to control an in situ leach mine wellfield" (1995). Theses and Dissertations @ UNI. 915.