Acidic wastewater from electroplating, metallurgy, mining and chemical plants carries sulfuric, hydrochloric or nitric acid together with dissolved metals such as Pb²⁺, Cd²⁺ and Cr⁶⁺. Neutralisation has to raise pH into the window where those metals precipitate — without overshooting into a range where amphoteric metals redissolve.
The self-buffering advantage
Magnesium oxide hydrates slowly to Mg(OH)₂ and dissolves only as acid is consumed. The result is a naturally self-buffering reaction: pH rises towards the magnesium hydroxide equilibrium and then plateaus, instead of spiking as it can with sodium hydroxide. Operators get a wider control window and less corrosive reagent handling.
What follows the pH shift
As pH rises, dissolved heavy metals form hydroxides that flocculate and settle. The magnesium ions left in solution are far less soluble-salt-forming than sodium, which reduces the dissolved solids load on downstream biological treatment and avoids the secondary salinity that caustic dosing creates.
Grade selection
A lightly calcined, reactive oxide with low acid-insolubles gives faster neutralisation and less inert sludge. Ask for reactivity and acid-insoluble data, and run a jar test on your own effluent — we can supply a sample lot and the corresponding certificate of analysis.
Need the measured values for a specific grade? Ask our technical team for the data sheet and a trial sample.