Halland Instruments AS

Zinc production: pH analyzers for the magnesium removal process.

Applications in other industries:

[Zinc production]
[Nickel production, chlorine process]
[Fertilizer industry]
[Nickel production, HPAL process]
[Alumina production]
[Titanium dioxide pigment prod.]
[Wastewater treatment]
[Cobalt production]
[Electroplating industry]
[Froth flotation, ore benefication]

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 the ZnOH is removed, then the solution is cooled in a crystallizer and the NaSO4 is 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 sodium hydroxide. 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 analyzers: 2

Sodium hydroxide process



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