PROCESS FOR REMOVAL AND STABILIZATION OF ARSENIC AND SELENIUM FROM AQUEOUS STREAMS AND SLURRIES

摘要

A process for removing or stabilizing arsenic and/or selenium from aqueousstreams or slurries is provided that includes contactingthe streams or slurry with a composition containing lanthanum chloride. Thelanthalum chloride composition can optionally contain variouslanthanides. The composition can optionally contain ferric or ferrous sulfate.The process is preferably conducted by adjusting the pH ofsolution to between about 8 or 10, adding 2 moles of lanthanum chloride forevery mole of arsenic or selenium ions present in solution,adding 5 to 6 moles ferric or ferrous ions for every mole of arsenic orselenium ions present in solution and adjusting the oxidation potentialof the solution to between 200-400 mV for removal of selenium ions and between100-200 mV for removal of arsenic ions. Using theprocesses of this invention, the selenium and arsenic concentrations can bereduced to less than currently acceptable limits and arsenic andselenium can be stabilized from leaching, decomposition or other degradationprocesses.