| Popis: |
The solubility of orpiment in Na2S-H2O solutions was measured under conditions ranging from 0·55 to 3·43 wt.% Na2S, temperatures from 25 to 200°C, and pressures from 100 to 1500 bars. Orpiment is highly soluble in Na2S solutions; mole ratios of dissolved As2S3 to total Na2S are about unity. Orpiment solubility increases nearly linearly with increasing Na2S concentration, but decreases non-linearly with increasing pressure. Temperature change affects orpiment solubility only slightly at temperatures below about 120°C, but above 120°C increasing temperature increases the solubility at an increasing rate. Factors that would lead to deposition of orpiment in nature are decreasing temperature, reactions with wall rocks, or acidification and oxidation reactions with ground water solutions. |
