Abstract
Abstract The main purpose of this paper is to demonstrate the potential of time-domain nuclear magnetic resonance (TD-NMR) technology for monitoring the concentrations of metal ions in water-based solutions. The main focus of this work was paramagnetic ions, such as Mn2+, Cu2+, Fe3+, Fe2+, Zn2+ and Ni2+, which are often the principal metal components in mining waters. Laboratory samples of different concentrations of single metals and mixtures of them and samples of real mining water were used in the relaxation rate (R 2) measurements. The measurements of single metal ions were used for the determination of the relaxivities of those ions. The concentrations of the ions in the mining water as a function of pH were also estimated by means of the X-ray fluorescence (XRF) method and ChemEQL software for calculating chemical speciation equilibria. Using these concentration values and the relaxivities of the metal ions, the total relaxation rate (R 2) results were then calculated. Principally, the results of these three different determinations are in relatively good agreement. It can be concluded that TD-NMR has great potential for monitoring metal ion concentrations during water treatment.
Highlights
Tightening requirements for the environmental quality of mining and process waters require more efficient purifi-Chemical precipitation is a conventional technology used to treat mining waters [1]
The main purpose of this paper is to demonstrate the potential of time-domain nuclear magnetic resonance (TD-NMR) technology for monitoring the concentrations of metal ions in water-based solutions
The concentrations of the ions in the mining water as a function of pH were estimated by means of the X-ray fluorescence (XRF) method and ChemEQL software for calculating chemical speciation equilibria
Summary
Tightening requirements for the environmental quality of mining and process waters require more efficient purifi-. Chemical precipitation is a conventional technology used to treat mining waters [1]. Chemical precipitation processes involve the addition of chemical reagents, followed by the separation of precipitated solids from clean water. Separation occurs in a clarifier, separation by filtration or membranes is possible. Chemical precipitation can be applied in water pools, in which case the precipitated solids can be left at the bottom of the pool. Precipitation can be induced by the addition of an alkali, sulfide, coagulant, or other reagent that will bond with dissolved metal ions. Raising the pH with the use of alkaline reagents, such as sodium hydroxide, causes certain dissolved metals to precipitate as hydroxides
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