阅读说明：本技术 一种盐酸体系溶液铁和铬选择性分离方法 (Method for selectively separating iron and chromium in hydrochloric acid system solution ) 是由 艾琳 常全忠 杨晓艳 陈学娇 王敏 刘世红 吕锦雷 马磊 魏丽梅 张亚东 柴明强 于 2019-10-23 设计创作，主要内容包括：本发明是一种盐酸体系溶液铁和铬选择性分离方法,(1)在含铁、铬的盐酸体系混合溶液中加入还原铁粉调节pH值；(2)待混合溶液pH值达到3-4时进行过滤分离,得到FeCl2溶液与铬的沉淀物,实现铁与铬的选择性分离。本发明的方法工艺简单、流程短、环境友好,尤其适合高纯铁溶液的净化及制备。(The invention relates to a method for selectively separating iron and chromium in a hydrochloric acid system solution, which comprises the following steps of (1) adding reduced iron powder into a hydrochloric acid system mixed solution containing iron and chromium to adjust the pH value; (2) and (3) filtering and separating when the pH value of the mixed solution reaches 3-4 to obtain FeCl2 solution and chromium precipitate, thereby realizing the selective separation of iron and chromium. The method has the advantages of simple process, short flow and environmental protection, and is particularly suitable for purifying and preparing high-purity iron solution.)

1. A hydrochloric acid system solution iron and chromium selective separation method, the iron ion content in hydrochloric acid system solution is 90-250g/L, the chromium ion content is 0.006-0.015g/L, characterized by that: the method comprises the following process steps: (1) adding a reducing agent into a hydrochloric acid system mixed solution containing iron and chromium to adjust the pH value of the solution to 3-4, wherein the reducing agent is iron powder, the reaction container is sealed after the iron powder is added, the temperature in the reaction process is normal temperature, and the reaction time is 20-24 hours; (2) the reactant is filtered and separated to obtain FeCl₂The solution and the chromium precipitate realize the selective separation of iron and chromium.

2. The method for selectively separating iron and chromium from a hydrochloric acid system solution as claimed in claim 1, characterized in that: the added iron powder is high-purity reduced iron powder.

3. The method for selectively separating iron and chromium from a hydrochloric acid system solution as claimed in claim 1, characterized in that: the mixed solution of the hydrochloric acid system containing iron and chromium is a solution prepared by dissolving iron salt or industrial electrolytic iron in hydrochloric acid.

Technical Field

The invention belongs to the technical field of high-purity iron production, and relates to a method for separating iron and chromium in a purification process of a solution required by high-purity iron preparation.

Background

The high-purity iron has good ductility, soft magnetic property, thermal property, conductivity, corrosion resistance and the like, so that the high-purity iron is widely applied to the fields of powder metallurgy, hard alloy, soft magnetic materials, electronic components, high-temperature alloy, aerospace, medical food additives, food deoxidizing agents and the like.

The high-purity iron has very strict requirements on the control of metal impurities, wherein the weight percentage of chromium is required to be less than 1.0 multiplied by 10^-4% of the total weight of the composition. Preparing high-purity iron by adopting an electrolytic method, wherein the requirement that the iron is Fe²⁺Form (a). Since iron and chromium are very similar in properties and have a co-deposition phenomenon during electrolysis, the chromium must be effectively separated from the solution before electrolysis. In the hydrochloric acid system, the iron and chromium are generally Fe²⁺And Cr³⁺Because the chemical properties of the iron solution and the chromium solution are similar and the adsorption-coprecipitation effect is achieved, the effective separation of the iron and the chromium in the iron and chromium solution is still a technical difficulty, and particularly the preparation of high-purity iron solution with extremely low requirement on chromium content is realized.

In order to effectively separate iron and chromium in the hydrochloric acid system solution, common methods include a solvent extraction method, a ferrous oxalate precipitation method, an ion exchange resin deferrization method, a selective phosphoric acid precipitation method and the like. Wherein, TBP is adopted to extract chromium, the separation effect is good, but the concentration of hydrochloric acid and the concentration of chromium are increased, thus easily oxidizing the extracting agent TBP and carrying out co-extractionThe extraction rate is high, the separation effect is reduced, and simultaneously TMP has strong corrosivity and high requirement on extraction equipment. Fe by P204 extraction³⁺High separation efficiency, but for Fe²⁺But much weaker and the stripping rate is extremely low, if reducing agent is added to Fe³⁺The reduction is carried out, and the introduction of other metal impurities is increased, which is not beneficial to the preparation of the high-purity iron melt. The ferrous oxalate precipitation method needs to strictly control the addition of oxalic acid, the process conditions are not easy to control, the process cost is high, and most importantly, the method can adsorb other metal impurities while precipitating iron, so that the preparation of high-purity iron solution cannot be met. The ion exchange resin iron removing method is characterized in that metal ions mainly exist in a form of matching anions in concentrated hydrochloric acid, the anion exchange resin can adsorb iron ions in the hydrochloric acid, but can adsorb other metal ions to different degrees at the same time, so that the iron purification is not facilitated, in addition, the method also has to strictly control the content of free chlorine in the hydrochloric acid before the exchange, otherwise, the service life of the resin is reduced, and the product quality is influenced. The selective phosphoric acid precipitation method is used for efficiently separating chromium and iron by selective phosphoric acid precipitation of chromium, but the method is not suitable for iron solution with higher concentration, and the separation effect of chromium and iron cannot meet the purification requirement of high-purity iron solution.

Disclosure of Invention

The invention aims to provide a selective separation method for iron and chromium in a hydrochloric acid system solution, which has the advantages of simple process, short flow, environmental friendliness and capability of effectively separating iron and chromium, and overcomes the defects in the prior art.

The invention is realized by the following technical scheme: a hydrochloric acid system solution iron and chromium selective separation method, the iron ion content in hydrochloric acid system solution is 90-250g/L, the chromium ion content is 0.006-0.015g/L, said method comprises the following process steps: (1) adding a reducing agent into a hydrochloric acid system mixed solution containing iron and chromium to adjust the pH value of the solution to 3-4, wherein the reducing agent is iron powder, the reaction container is sealed after the iron powder is added, the temperature in the reaction process is normal temperature, and the reaction time is 20-24 hours; the chromium is fully hydrolyzed under the pH condition to form a precipitate; (2) the reactant is filtered and separated to obtain FeCl₂Precipitation of solution with chromiumPrecipitates to realize the selective separation of iron and chromium.

The added iron powder is high-purity reduced iron powder.

The mixed solution of the hydrochloric acid system containing iron and chromium is a solution prepared by dissolving iron salt or electrolytic iron in hydrochloric acid.

The mechanism of the invention is as follows: because hydrochloric acid has certain reducibility, iron and chromium in ferrous chloride solution prepared by dissolving iron salt and industrial electrolytic iron in hydrochloric acid are kept in Fe²⁺、Cr³⁺Adjusting the pH value of the solution by using high-purity reduced iron powder to avoid Fe²⁺And a small amount of oxidized Fe³⁺Hydrolysis of pH range to Cr³⁺Hydrolyzing the precipitate, filtering and separating to obtain chromium hydroxide precipitate and ferrous chloride solution, and realizing the selective separation of iron and chromium.

The invention has the following advantages:

(1) the process is simple to operate, short in flow and low in cost; (2) only high-purity reduced iron powder is added in the separation process of iron and chromium, and other impurities are not introduced, so that the preparation of a high-purity iron solution is facilitated; (3) the separation effect of iron and chromium is ideal, the separation effect is not influenced by chloride ions and the concentration of the solution, chromium is separated from the iron-containing solution in a precipitation form, and the chromium can adsorb other impurities to be removed together when the precipitate is formed, so that the requirement of high-purity iron preparation on chromium element in the electrolyte is met. (4) The concentration range for the separation of the ferrochrome is wide.

Detailed Description

A method for selectively separating iron and chromium in a hydrochloric acid system solution sequentially comprises the following steps:

(1) adding reduced iron powder into a hydrochloric acid system mixed solution containing iron and chromium; the content of iron ions in the hydrochloric acid system mixed solution containing iron and chromium is 90-250g/L, and the content of chromium ions is 0.006-0.015 g/L; adding reduced iron powder to adjust the pH value of the solution to 3-4; (2) the temperature in the reaction process is normal temperature, the reaction time is 24 hours, chromium is fully hydrolyzed to form chromium hydroxide precipitate, and iron is kept in the solution by ferrous chloride; (3) filtering and separating to obtain FeCl₂The solution and the chromium precipitate realize the selective separation of iron and chromium.