| Acid mine drainage (AMD), caused by the biological oxidation of sulfidic materials, frequently contains arsenic along with higher concentrations of dissolved iron. The first part of present work is directed towards the removal of arsenic from synthetic AMD. The pH of the solution is raised by electrochemical reduction of H+ to hydrogen gas; arsenic is co-precipitated with iron(III) hydroxide formed in situ. Essentially quantitative removal of arsenic and iron is achieved with current efficiencies of about 85% when the pH of the effluent is increased to 4-7.; The second part of the study deals with removing arsenic from nickel refining electrolyte by first electrochemically oxidizing As(III) to As(V) and then removing it by co-precipitation with iron hydroxide. An authentic sample supplied by INCO was successfully purified using this process. Copper was recovered as a pure metal by electrodeposition. The process was scaled up from 40 mL to 1 L capacity. |
