Removal of Metals by Sulphide Precipitation Using Na2S and HS−-Solution
| Autor: | Emma-Tuulia Nurmesniemi, Ulla Lassi, Hanna Prokkola |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
metal hydroxides
Hydrogen General Chemical Engineering Evaporation Ionic bonding chemistry.chemical_element 02 engineering and technology precipitation 010501 environmental sciences 01 natural sciences metal sulphides lcsh:Chemistry Metal chemistry.chemical_compound 0105 earth and related environmental sciences Chemistry Precipitation (chemistry) General Engineering 021001 nanoscience & nanotechnology Acid mine drainage Sulfur General Energy lcsh:QD1-999 Environmental chemistry visual_art visual_art.visual_art_medium Hydroxide 0210 nano-technology acid mine drainage |
| Zdroj: | ChemEngineering Volume 4 Issue 3 ChemEngineering, Vol 4, Iss 51, p 51 (2020) |
| ISSN: | 2305-7084 |
| Popis: | Precipitation of metals as metal sulphides is a practical way to recover metals from mine water. Sulphide precipitation is useful since many metals are very sparingly soluble as sulphides. Precipitation is also pH dependent. This article investigates the precipitation of metals individually as sulphides and assesses which metals are precipitated as metal hydroxides by adjustment of the pH. The precipitation of different metals as sulphides was studied to determine the conditions under which the HS&minus solution from the sulphate reduction reaction could be used for precipitation. H2S gas and ionic HS&minus produced during anaerobic treatment could be recycled from the process to precipitate metals in acidic mine drainage (AMD) prior to anaerobic treatment (Biological sulphate reduction), thereby recovering several metals. Precipitation of metals with HS&minus was fast and produced fine precipitates. The pH of acid mine water is about 2&ndash 4, and it can be adjusted to pH 5.5 before sulphide precipitation, while the precipitation, on the other hand, requires a sulphide solution with pH at 8 and the sulphide in HS&minus form. This prevents H2S formation and mitigates the risk posed from the evaporation of toxic hydrogen sulphur gas. This is a lower increase than is required for hydroxide precipitation, in which pH is typically raised to approximately nine. After precipitation, metal concentrations ranged from 1 to 30 &mu g/L. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|