Process monitor for an ammoniacal nickel solution employing an infrared light-emitting diode and a log-ratio amplifier

Abstract

An infrared light-emitting diode with peak-emission intensity at 950 nm is used to monitor, on-line, the concentration of a nickel hexamine carbonate solution. This provides a continuous read-out of the concentration in an extraction stream and is used to control the process at a nickel refinery. Previously the data was obtained by frequent manual sampling and determination of the concentration by AAS. The transducer employs fibre-optic cables and a beam splitter in order to allow complete sealing of the opto-electronics and correction for intensity fluctuations of the light source with a log-ratio amplifier. These measures allow the device to function with good performance in a hostile environment of ammonia vapours and large temperature fluctuations.