JP2008119690A5 - - Google Patents

Description

The present inventors have made intensive studies to solve the above problems, the addition of bivalent iron ions in a solution containing pentavalent arsenic, the molar ratio of iron to arsenic in the solution to (Fe / As) Iron and arsenic with a very low elution concentration of arsenic by adding an oxidizing agent and reacting at a temperature of 70 ° C. or higher while stirring at atmospheric pressure and then separating the solid and liquid to recover the solid content. As a result, the present invention was completed.

That is, the processing method of the arsenic containing solution according to the present invention, in addition to bivalent iron ions in a solution containing pentavalent arsenic, the molar ratio of iron to arsenic in the solution to 1 or more, the addition of oxidant large After reacting at a temperature of 70 ° C. or higher while stirring under atmospheric pressure, the solid content is separated and solid content is recovered.

In this method for treating an arsenic-containing solution, the molar ratio of iron to arsenic is preferably 1 to 1.5, and the reaction temperature is preferably 95 ° C. or lower. Further, the concentration of arsenic in the solution is preferably 10 g / L or more, and more preferably 20 g / L or more. Further, it is preferable to add divalent iron ions to a solution containing pentavalent arsenic so that the pH of the solution is 2 or less. Further, it is preferable to add iron (II) sulfate heptahydrate as divalent iron ions to the solution. Furthermore, oxygen gas can be used as an oxidizing agent.

Claims (10)

The solution was added divalent iron ions containing pentavalent arsenic, the molar ratio of iron to arsenic in the solution to 1 or more, at a temperature 70 ° C. or more while stirring under atmospheric pressure by adding an oxidizing agent After that, a method for treating an arsenic-containing solution, wherein solid content is separated and solid content is recovered. The method for treating an arsenic-containing solution according to claim 1, wherein the molar ratio of iron to arsenic is 1 to 1.5. The method for treating an arsenic-containing solution according to claim 1 or 2 , wherein the temperature is 95 ° C or lower. The method for treating an arsenic-containing solution according to any one of claims 1 to 3, wherein the concentration of arsenic in the solution is 10 g / L or more. The method for treating an arsenic-containing solution according to any one of claims 1 to 3 , wherein the concentration of arsenic in the solution is 20 g / L or more. The treatment of an arsenic-containing solution according to any one of claims 1 to 5, wherein the divalent iron ions are added to the solution containing pentavalent arsenic to make the pH of the solution 2 or less. Method. The method for treating an arsenic-containing solution according to any one of claims 1 to 6 , wherein iron (II) sulfate heptahydrate is added to the solution as the divalent iron ion. Characterized in that the oxidizing agent is oxygen gas, the processing method of the arsenic containing solution according to any of claims 1 to 7. The arsenic-containing solution is obtained by adding an arsenic-containing substance to an alkaline solution and leaching the alkali while oxidizing to obtain a leaching solution containing arsenic by solid-liquid separation and oxidizing the alkaline-earth metal or its A step of solid-liquid separation after adding a salt to obtain a residue containing an arsenic and alkaline earth metal compound, a step of washing the residue and adding it to a sulfuric acid solution, and then solid-liquid separation to obtain an arsenic-containing solution; The method for treating an arsenic-containing solution according to any one of claims 1 to 8 , wherein the arsenic-containing solution is produced by a method comprising: In manufacturing the arsenic-containing solution, an arsenic-containing material containing sulfur is used as the arsenic-containing material, or when the arsenic-containing material does not contain sulfur, sulfur is added to the arsenic-containing material or the leachate In addition, the amount of the alkaline earth metal or salt thereof added to the leachate should be more than the amount of the alkaline earth metal or salt required to produce the arsenic and alkaline earth metal compound. The processing method of the arsenic containing solution of Claim 9 characterized by these.