JPS6012283B2 - Method for recovering valuable components from ferrous ammonium sulfate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the use of ferrous ammonium sulfate containing heavy metals.

When chromium ore is used as ferrochrome and the extract obtained by sulfuric acid extraction is electrolyzed to obtain metallic chromium, the iron content is removed as ferrous ammonium sulfate (hereinafter referred to as Mohr's salt).

In addition to iron, this Mohr salt contains heavy metal components such as chromium, nickel, and manganese. Various methods of effectively utilizing these Sosei Mohr salts have been studied.

For example, when the contained metal is hydroxide, P at the time of precipitation formation
There is a method in which each component is separated using the difference in the H range, for example, the iron content is converted into iron hydroxide, which is then ground in a barrel and used as iron oxide for ferrite or pengara. However, this method is not a preferable method because not only is the furnace filtration property extremely poor when separating the precipitate, but also nickel, manganese, etc. are mixed into the obtained iron oxide. Another method is to add slaked lime to an aqueous Mohr's salt solution and blow in air to recover ammonia gas generated when hydroxide is oxidized and calcium sulfate generated. Although this method is relatively easy to operate, it has the disadvantage that heavy metals contained in Mohr's salt remain in the calcium sulfate, and further treatment of these metals is required. The present inventors researched methods for safely and reliably separating and recovering the heavy metals contained in Mohr's salt, and also for recovering ammonium sulfate, and as a result, discovered a method for separating and recovering these heavy metals using a solvent extraction method. The invention has been completed.

The gist of the present invention is to prepare a solution obtained by dissolving Mohr's salt in water, precipitate and separate the chromium contained in Mohr's salt, and add ammonia gas or ammonia water to the filtrate to remove iron. While adjusting the pH to such an extent that no precipitate is formed,
Divalent iron ions are converted to trivalent iron ions using air, oxygen, or an oxygen-containing gas such as nitrogen oxide, and then trioctyl phosphate, tributyl phosphate, tributyl phosphine oxide, and trioctyl phosphine oxide are converted into trivalent iron ions. The iron content is extracted with an organic neutral phosphate such as 2-ethylhexyl ammonium phosphate, and then an acid such as sulfuric acid or hydrochloric acid, or water is added to this organic phase to extract the iron content as ferrous sulfate. It's about collecting.

The organic solvent liberated in this process is recycled for the extraction of the iron. The residual aqueous solution after the iron content has been removed by solvent extraction is treated with ammonia gas or aqueous ammonia, and the concentration is preferably adjusted to 7.0 to prevent precipitation of nickel and manganese contained in the aqueous solution. Metal impurities such as nickel and manganese are extracted and removed using organic neutral phosphates such as 2-ethylhexyl ammonium phosphate, carboxylic acids such as naphthenic acid, or organic solvents such as high molecular weight amines. From the organic phase from which metal impurities have been extracted, metals are extracted and separated using sulfuric acid or the like. As diluents for these organic solvents, carbons or their chlorides such as kerosene and n-hexane trichlorethylene, aromatic hydrocarbons such as xylene, toluene, and benzene, etc. are used.

When diluting the organic solvent with these diluents, the solvent concentration is 5 to 50%, preferably 10 to 20%.The purified ammonium sulfate solution obtained by removing metal impurities such as nickel and manganese is concentrated by evaporation. By doing this, it is possible to recover high-purity ammonium sulfate without coloring.

When separating the chromium contained in Mohr's salt, ammonia gas or ammonia water is added until the pH of the Mohr's salt aqueous solution is adjusted to 5.5. It is not preferable to approach the G hill because iron will precipitate. or,
It is preferable to prevent the iron content in this aqueous solution from being oxidized.

In order to extract iron with a solvent, it is necessary to adjust the FH of the aqueous solution to a high pH so that iron does not precipitate.
If the H content increases too much, iron precipitates will form, and the separation between the solvent and the aqueous solution will be significantly impaired.

The solvent-extracted iron is back-extracted with a solution of sulfuric acid or hydrochloric acid, preferably 1-state sulfuric acid.

The ferric sulfate solution back-extracted with sulfuric acid can be evaporated and crystallized to form ferric sulfate, or neutralized with an alkali, separated and then calcined to recover high-purity iron oxide. Since the present invention is configured as described above, the iron content in ferrous ammonium sulfate can be almost completely recovered as high-purity iron oxide without being discarded.
This can be used for ferrite or high-grade steel.

Furthermore, the recovered ammonium sulfate can be used for fertilizers, etc., making it an extremely useful method from a resource-saving perspective. Example-1 The generated ferrous ammonium sulfate obtained when obtaining metal chromium by electrolyzing ferrochrome was dissolved in water to obtain ``Cr300.0''.
75 evening/so, Mh210.041 evening/soto Nio. 02
9 Tanok, ferrous ammonium sulfate [FeS04 (NH
4) 2SQ・Thin 20〕210 evening/Concentrated ammonia water was added to this solution to remove spots in the solution.
The chromium content was precipitated and removed as chromium hydroxide.

Next, ammonia water was added to the precipitated filtrate and air was brought into contact with it using a packed tower to oxidize the iron content.

Claims (1)

[Claims] 1 Dissolve ferrous ammonium sulfate containing heavy metals in water, precipitate and separate the chromium content using an alkali or alkaline aqueous solution, oxidize the iron content using an oxygen-containing gas, and convert the iron content into an organic neutral phosphate. 1. A method for recovering valuable components from ferrous ammonium sulfate, which comprises extracting and separating the ferrous ammonium sulfate, and then recovering iron from the extract.