Method for extracting chromium from solution containing chromium ions and iron ions

Abstract

A method for extracting chromium from a solution containing chromium ions and iron irons comprises the steps as follows: (1), the temperature of the solution containing the chromium ions and the iron ions is controlled to be 15-20 DEG C, and then a potassium hydroxide solution or a potash solution is added into the solution under the condition of agitation, and the uniform agitation is performed; (2), the pH value is regulated to 0-1.5, and a salting-out mother solution is obtained; (3), the salting-out solution is aged under the condition of 0-60 DEG C, and a chromium element is separated out in the form of a purple crystal KCr(SO4)2.12H2O; (4), the aged material is filtered, the purple crystal is separated out, and the purple crystal is washed and dried, so that the KCr(SO4)2.12H2O crystal is obtained. The method changes the multi-step impurity removal into selective extraction, is mild in conditions, low in cost, and avoids 'three wastes' discharge; no Cr(VI) is generated during the whole process, and purity elements can be efficiently and comprehensively utilized.

Description

technical field [0001] The invention belongs to the technical field of mineral processing, in particular to a method for extracting chromium from a solution containing chromium ions and iron ions. Background technique [0002] At present, the production process of chromium salt from chromite mainly includes calcium roasting process, calcium-free roasting process and molten salt liquid phase oxidation process, all of which have the problem of Cr(Ⅵ) pollution. In recent years, countries around the world have done a lot of research work on the comprehensive treatment of Cr(Ⅵ) pollution, but a cost-effective treatment method has not yet appeared. Therefore, the industrialization transition from terminal treatment to cleaner production has become an inevitable trend to fundamentally solve this stubborn disease. [0003] The sulfuric acid leaching process of chromite ore and ferrochromium alloy is a new technology for the preparation of chromium salts without producing Cr(Ⅵ), but...

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Problems solved by technology

In a solution with a pH value of 2-4, Fe 3+ Precipitate in the form of goethite, and separate from the liquid phase by filtration after the crystallization grows; this method is cumbersome to operate, and the pH value is difficult to control accurately, and it is easy to form adsorbent jelly, which affects the separation effect of chromium and iron

[0006] Mohr’s salt method is to add excess ammonium sulfate to the acidic solution, heat and keep it warm for a long time, and then quickly cool the solution to precipitate iron in the form of ammonium ferrous sulfate crystals; this method is difficult to achieve a high iron removal rate, there will be A small amount of iron remains in solution

[0007] The ferrous oxalate method is to first add a reducing agent to make Fe 3+ reduced to Fe 2+ , and then adjust the pH value of the solution to the range of 1 to 4, add oxalic acid solution to precipitate iron; the iron removal rate of this method can reach more than 98%, but it still cannot remove all iron

[0008] The yellow potassium iron vanadium method is to add K to the solution + 、Na + , NH 4 + Plasma, make it with Fe 3+ Forms crystals in sulfate solution, with M 2 Fe 6 (SO 4 ) 4 (OH) 12 (M stands for K, Na, NH 4 + etc.) are precipitated and separated; this method has a good separation effect of chromium and iron, but the filterability is not stable

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