Method for immobilizing arsenic, and arsenic-containing vitrified waste

Patent metadata

Field	Value
Publication number	US-10758954-B2
Application number	US-201616064153-A
Country	US
Kind code	B2
Filing date	Dec 21, 2016
Priority date	Dec 23, 2015
Publication date	Sep 1, 2020
Grant date	Sep 1, 2020

Abstract

A method for immobilizing arsenic includes adding calcium arsenate to a glass-forming material containing iron, silica, and alkaline components so that an iron/silica weight ratio is in a range of 0.5 to 0.9 and an amount of alkaline components is in a range of 14 wt % to 26 wt %, and thereby incorporating the arsenic into a glass solidified body. For example, the method for immobilizing arsenic may include: adding an alkaline solution and an oxidizing agent to a copper-arsenic-containing substance, and thereby carrying out an oxidizing leaching; separating a leach residue by solid-liquid separation; adding calcium hydroxide to a recovered alkaline arsenate solution to generate calcium arsenate; and adding the glass-forming material to the recovered calcium arsenate so that the iron/silica weight ratio and the amount of alkaline components are in the above-mentioned ranges, and thereby incorporating the arsenic into the glass solidified body.

First claim

The invention claimed is:

1. A method for immobilizing arsenic, the method comprising:
adding an alkaline solution and an oxidizing agent to a copper-arsenic-containing substance, and thereby carrying out an oxidizing leaching;
separating a leach residue by solid-liquid separation;
adding calcium hydroxide to a recovered alkaline arsenate solution to generate calcium arsenate;
adding the recovered calcium arsenate to a glass-forming material containing iron, silica and alkaline components so that an iron/silica weight ratio is in a range of 0.5 to 0.9 and an amount of alkaline components is in a range of 14 wt % to 26 wt %, and thereby incorporating the calcium arsenate into a glass solidified body.

2. The method for immobilizing arsenic according to claim 1 ,
wherein the copper-arsenic-containing substance is a copper-arsenide-containing slime,
sodium hydroxide and the oxidizing agent are added to the copper-arsenide-containing slime, a mixture is heated to leach the arsenic, and meanwhile the leach residue is separated by solid-liquid separation,
calcium hydroxide is added to a recovered sodium arsenate solution to generate calcium arsenate, and
the glass-forming material is added to the recovered calcium arsenate so that the iron/silica weight ratio and the amount of alkaline components are in the ranges, and thereby incorporating the calcium arsenate into the glass solidified body.

3. The method for immobilizing arsenic according to claim 2 ,
wherein calcium hydroxide is added to the sodium arsenate solution to generate calcium arsenate, a solution containing the calcium arsenate is subjected to solid-liquid separation to recover the calcium arsenate, and meanwhile a filtrate containing sodium hydroxide is returned to an oxidizing leaching step to reuse the filtrate as an alkaline source for oxidizing leaching.

Assignees

• Mitsubishi Materials Corp

Inventors

• Nabei Atsuhiro
• MIRUVARIEFU Rinato
• Okada Satoshi

Classifications

• B09B3/29 Primary

  involving a melting or softening step · CPC title

• C22B3/22

  by physical processes, e.g. by filtration, by magnetic means {, or by thermal decomposition} (treatment or purification of solutions by liquid-liquid extraction C22B3/26) · CPC title

• C22B7/006 Primary

  Wet processes · CPC title

• Y02P10/20

  Recycling · CPC title

• C22B30/04

  Obtaining arsenic {(extraction of metal compounds by leaching in organic solutions C22B3/16; treatment or purification of solutions by adsorption on solids C22B3/24, by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42)} · CPC title