Water intensive processes are widely used in the pulp and paper, mining, and food industries, as well as in water and wastewater treatment. These processes are based on the interaction between the particles of basic material within aqueous substance. Tightening requirements for the environmental quality of mining and process waters necessitate the development of more efficient purification methods. Current water quality measurements are not able to cope with certain significant contaminants like metal and sulfate concentrations in real time. In addition, presently used water quality monitoring systems require regular maintenance and calibration, which reduces their cost-efficiency.
Online measurement of metal concentrations will be the first step towards more efficient and optimized control of water intensive processes. Better measurement and control applications enable the optimization of processes, which makes it possible to achieve 1) optimal purification, 2) energy savings via the optimization of mixing processes, and 3) chemical savings via the optimization of chemical dosage.
High-resolution nuclear magnetic resonance (NMR) spectroscopy is one of the most informative analytical method in chemistry, but in practice, it is difficult to apply it to online process control. Time domain nuclear magnetic resonance method (TD-NMR) is becoming highly attractive for industrial applications due to relatively low price, mobility, easy operating, and simple sample preparation procedure. The most successful applications of TD-NMR confirmed by international standards are solid fat content determination in food and water and oil content in oilseeds. Moreover, NMR is sensitive to the presence of paramagnetic ions, which makes it a potentially applicable technology for measuring metal concentrations in mining waters.
In this study, we have utilized the TD-NMR technology for monitoring the concentrations of metal ions in water solution. We have concentrated on paramagnetic ions such as Mn, Cu, Fe and Ni, which are the principal metal components in mining waters. We have used both test samples consisting of different concentrations of single metals and mixtures of them, and real mining water samples. The preliminary results from these measurements are promising.