PROCESS MONITOR FOR AN AMMONIACAL NICKEL SOLUTION EMPLOYING AN INFRARED LIGHT-EMITTING DIODE AND A LOG-RATIO AMPLIFIER

An infrared light-emitting diode with peak-emission intensity at 950 n m is used to monitor, on-line, the concentration of a nickel hexamine carbonate solution; This provides a continuous read-out of the concent ration 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 comp lete sealing of the opto-electronics and correction for intensity fluc tuations of the light source with a log-ratio amplifier, These measure s allow the device to function with good performance in a hostile envi ronment of ammonia vapours and large temperature fluctuations.