| 摘要 |
Sulfate anions and divalent metal ions in water are removed by treating sulfate-containing water, at a pH of 11-12.5, with aluminum chloride and calcium chloride, optionally together with lime, to form solid ettringite and similar crystalline species. Sulfate is removed as part of the ettringite or ettringite-like materials, but calcium content can be reduced at the same time even though calcium chloride is used as an additive to the treated water. Lime may be used also as a supplemental source of calcium and to help raise the pH. Iron may also be removed by oxidation in a variation of the process. In well treatment, divalent metal ions in flowback fluids can reduce the amount of calcium otherwise necessary to form the solid materials, thus further facilitating recycling of the fluid. |
