The effect of magnesium on partial sulphate removal from mine water as gypsum

J Environ Manage. 2015 Aug 15:159:143-146. doi: 10.1016/j.jenvman.2015.05.009. Epub 2015 Jun 8.

Abstract

The aim of this research was to investigate the effect of magnesium on the removal efficiency of sulphate as gypsum from mine water. The precipitation conditions were simulated with MINEQL + software and the simulation results were compared with the results from laboratory jar test experiments. Both the simulation and the laboratory results showed that magnesium in the mine water was maintaining sulphate in a soluble form as magnesium sulphate (MgSO4) at pH 9.6. Thus magnesium was preventing the removal of sulphate as gypsum (CaSO4·2H2O). However, change in the lime precipitation pH from 9.6 to 12.5 resulted in magnesium hydroxide (Mg(OH)2) precipitation and improved sulphate removal. Additionally, magnesium hydroxide could act as seed crystals for gypsum precipitation or co-precipitate sulphate further enhancing the removal of sulphate from mine water.

Keywords: Lime precipitation; Magnesium ion; Mine water; Sulphate removal; Wastewater treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calcium Compounds / chemistry
  • Calcium Sulfate / analysis
  • Calcium Sulfate / chemistry*
  • Magnesium / chemistry*
  • Oxides / chemistry
  • Sulfates / analysis
  • Sulfates / chemistry*
  • Water / chemistry
  • Water Pollutants, Chemical / chemistry
  • Water Purification / methods*

Substances

  • Calcium Compounds
  • Oxides
  • Sulfates
  • Water Pollutants, Chemical
  • Water
  • lime
  • Magnesium
  • Calcium Sulfate