Method for preparing arsenic trioxide from arsenic sulfide waste

Abstract

The invention provides a method for preparing arsenic trioxide from arsenic sulfide waste. The arsenic sulfide waste is soaked in a sodium hydroxide solution to extract arsenic sulfide, arsenic sulfide mixes with an excessive amount of arsenic acid, and the mixture reacts at a temperature ranging from 40 DEG C to 95 DEG C for 0.5 to 3 hours, to produce a mixture containing arsenous acid and elemental sulfur; the mixture containing arsenous acid and elemental sulfur mixes with 2 to 5 times (by mass) of water and then oxygen gas is introduced so that arsenous acid is oxidized into arsenic acid,and the reaction product is filtered to remove elemental sulfur and thus to produce an arsenic acid solution; and the arsenic acid solution is reduced by sulfur dioxide gas to arsenous acid with a lower solubility, the reaction liquid is distilled under a reduced pressure to produce a saturated solution of arsenous acid, the saturated solution of arsenous acid is cooled so that arsenous acid is crystallized and then filtered to produce a filter cake of arsenous acid, and the filter cake of arsenous acid is dried and pulverized to obtain an arsenic trioxide product. The method has a short process flow, increases the recovery rate of arsenic, avoids the production of secondary pollutants, adopts simple equipment, greatly reduces the cost of arsenic recovery and is worthy to be widely applied.

Description

technical field

[0001] The invention relates to the technical field of comprehensive utilization and treatment of arsenic-containing wastewater, in particular to a method for preparing arsenic trioxide from arsenic sulfide waste residue. Background technique

[0002] For a long time, most of the arsenic-containing waste residues have been treated by hoarding and storage. With the accumulation of high-concentration arsenic-containing wastes, the arsenic-containing waste residues have caused soil and river pollution, and the phenomenon of endangering people's life and health has become more and more serious. In order to prevent secondary pollution, it is necessary to treat the arsenic sulfide waste residue.

[0003] In particular, after years of mining, arsenic ore resources have been extremely limited. Due to the special use of arsenic in agriculture, electronics, medicine, metallurgy, chemical industry and other fields, it can be used to prepare herbicides, wood preservativ...