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Manufacturer of proprietary pH analysers for the hydrometallurgical zinc industry.

Halland Instruments AS

Applications overview:

APPLICATION: Automatic pH control of the Magnesium removal process.

Process description:
To prevent the build-up of magnesium and other elements in the circulated zinc solution (the inventory) a fraction of the spent acid is sent to a process called "the discard plant". Here the spent acid is neutralized in two small tanks with NaOH and NaSO4 and ZnOH is formed. The solution goes to a belt filter where ZnOH removed, then the solution is cooled in a crystallizer and NaSO4 removed with a belt filter. The NaSO4 is reused in the jarosite process. The effluent is discharged to the effluent water treatment plant. The pH in the second tank is controlled automatically by a controller and a valve which adds NaOH. The pH in the third tank is measured.

pH range: 3-6 pH
Temperature: 50 - 60 C.
Flow: 3 m/h
Tanks: 3 tanks with a capacity of 3 m - 5 m
Number of analyser: 2



pH analyser on top of discard Tank-2 after three years of operation. The pH measurement is used for automatic control of the NaOH valve.