Method for extracting and removing iron from iron-containing waste nitric acid solution

Abstract

The invention relates to the technical field of hydrometallurgy, and particularly discloses a method for extracting and removing iron from an iron-containing waste salpeter solution, which comprises the following steps: extracting the iron-containing waste salpeter solution by adopting an extraction organic phase consisting of an extraction agent A and sulfonated kerosene, and carrying out phase splitting to obtain an iron-containing loaded organic phase and an iron-removed nitric acid raffinate water phase, therefore, complete separation of Fe < 3 + > in the iron-containing waste nitric acid solution is directly realized. The process is simple and continuous in operation, no extra reagent is introduced into an original nitric acid system, and the method is very suitable for recycling of the iron-containing waste nitric acid solution after iron is removed.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for extracting and removing iron from an iron-containing waste nitric acid solution. Background Art

[0002] Nitric acid is a commonly used inorganic strong acid with strong oxidizing and corrosive properties, and is therefore widely used in metallurgy, chemical industry and other fields. In the conventional production process of stainless steel (degreasing, water washing, pickling, water washing, passivation), a large amount of nitric acid solution of different concentrations is required in both the pickling and passivation stages. Accordingly, a large amount of waste nitric acid solution containing iron is obtained. These waste nitric acid solutions have the characteristics of large differences in nitric acid concentration and iron concentration. For example, the pickling process is mainly to remove the oxide scale on the surface of the annealed steel before the surface electroplating and spraying of the blank, and the waste nitric acid solution obtained has a low nitric acid concentration and a high iron concentration; while the passivation process is mainly to passivate the blank under the action of concentrated nitric acid to form a dense oxide film, and the waste nitric acid solution obtained has a high nitric acid concentration and a low iron concentration. In order to realize the recycling and reuse of these waste nitric acid solutions containing iron, it is necessary to separate the iron ions and nitric acid in the solution system without introducing other reagents into the solution system.

[0003] Since there is no efficient and universal method for extracting and removing iron from waste nitric acid solutions containing iron with a wide range of nitric acid concentrations, the main research on the separation method of iron and nitric acid in waste nitric acid solutions containing iron is still focused on how to separate the acid and leave the iron in the solution system. Common methods include evaporation recovery acid method, electrolytic acid concentration method, vacuum distillation method, etc. However, there are generally high energy consumption, expensive equipment, high corrosion resistance cost and other disadvantages, which greatly limit large-scale promotion and application. Therefore, the development of a method that can be applied to extract and remove iron from waste nitric acid solutions containing iron with a wide range of nitric acid concentrations is of great practical significance for the subsequent recovery and reuse of nitric acid.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a method for extracting and removing iron from an iron-containing waste nitric acid solution.

[0006] The present invention is achieved through the following technical solutions: A method for extracting and removing iron from an iron-containing waste nitric acid solution, the method comprising the following steps: The iron-containing waste nitric acid solution is extracted with an extraction organic phase composed of an extractant A and sulfonated kerosene, and after phase separation, an iron-loaded organic phase and a nitric acid raffinate aqueous phase after iron removal are obtained; wherein the volume ratio of the extractant A to the sulfonated kerosene is 1-3:7-9, and the chemical structural formula of the extractant A is shown in the following formula: ; The method is suitable for nitric acid concentration of 1.0~12mol / L, Fe 3+ The concentration of iron-containing waste nitric acid solution is 0.5~6 g / L. Within this concentration range, Fe 3+ The extraction rate is over 99.8%.

[0007] Preferably, the extraction method is countercurrent or cross-current extraction; the extraction phase ratio O / A is 1-3:1; the extraction stage is 1-3; and the extraction time is 5-10 min.

[0008] The beneficial effects of the present invention are as follows: The present invention adopts sulfonated kerosene as a diluent to dissolve the viscous paste extractant A to form a fluid extraction organic phase, and ingeniously utilizes the hydrogen ion ion exchange effect of the hydroxyl group in the molecular structure of the extractant A and the strong electron coordination effect of phosphorus and oxygen, so as to achieve the effect of Fe ions in a wide nitric acid concentration range (1.0-12 mol / L) of the nitric acid system. 3+ The efficient extraction effect of Fe in the iron-containing waste nitric acid solution is finally achieved. 3+ The process is simple, the operation is continuous, and no additional reagents are introduced into the original nitric acid system. It is very suitable for the recycling of iron-containing waste nitric acid solution after iron is removed. DETAILED DESCRIPTION

[0009] The following is a further description of the present invention, rather than a limitation of the present invention.

[0010] Example 1: A method for extracting and removing iron from iron-containing waste nitric acid solution The composition of the iron-containing waste nitric acid solution is as follows: Fe 3+ 2.98 g / L, nitric acid concentration 12 mol / L. According to the volume ratio, 30% extractant A and 70% sulfonated kerosene were prepared to form the extraction organic phase. The extraction organic phase and the iron-containing waste nitric acid solution were subjected to a first-stage cross-current extraction at a ratio of O / A of 1:1 for 5 minutes. 3+ The extraction rate is 100%, achieving the extraction of Fe in the iron-containing waste nitric acid solution. 3+ of extraction removal.

[0011] Example 2: A method for extracting and removing iron from iron-containing waste nitric acid solution The composition of the iron-containing waste nitric acid solution is as follows: Fe 3+ 2.03 g / L, nitric acid concentration 8 mol / L. According to the volume ratio, 20% extractant A and 80% sulfonated kerosene were prepared to form the extraction organic phase. The extraction organic phase and the iron-containing waste nitric acid solution were subjected to two-stage countercurrent extraction at a ratio of O / A of 1:1 for 10 minutes. 3+ The extraction rate is 100%, achieving the extraction of Fe in the iron-containing waste nitric acid solution. 3+ of extraction removal.

[0012] Example 3: A method for extracting and removing iron from iron-containing waste nitric acid solution The composition of the iron-containing waste nitric acid solution is as follows: Fe 3+ 0.5 g / L, nitric acid concentration 4 mol / L. According to the volume ratio, 20% extractant A and 80% sulfonated kerosene were prepared to prepare the extraction organic phase. The extraction organic phase and the iron-containing waste nitric acid solution were subjected to a first-stage countercurrent extraction at a ratio of O / A of 1:1 for 10 minutes. 3+ The extraction rate is 100%, achieving the extraction of Fe in the iron-containing waste nitric acid solution. 3+ of extraction removal.

[0013] Example 4: A method for extracting and removing iron from iron-containing waste nitric acid solution The composition of the iron-containing waste nitric acid solution is as follows: Fe 3+ 2.03 g / L, nitric acid concentration 6 mol / L. According to the volume ratio, 10% extractant A and 90% sulfonated kerosene were prepared to prepare the extraction organic phase. The extraction organic phase and the iron-containing waste nitric acid solution were subjected to two-stage countercurrent extraction at a ratio of O / A of 2:1 for 10 minutes. 3+ The extraction rate is 100%, achieving the extraction of Fe in the iron-containing waste nitric acid solution. 3+ of extraction removal.

[0014] Example 5: A method for extracting and removing iron from iron-containing waste nitric acid solution The composition of the iron-containing waste nitric acid solution is as follows: Fe 3+ 1.03 g / L, nitric acid concentration 2 mol / L. According to the volume ratio, 10% extractant A and 90% sulfonated kerosene were prepared to form the extraction organic phase. The extraction organic phase and the iron-containing waste nitric acid solution were subjected to three-stage countercurrent extraction at a ratio of O / A of 1:1 for 10 minutes. 3+ The extraction rate is 99.83%, achieving the extraction of Fe from iron-containing waste nitric acid solution. 3+ of extraction removal.

[0015] Example 6: A method for extracting and removing iron from iron-containing waste nitric acid solution The composition of the iron-containing waste nitric acid solution is as follows: Fe 3+ 5.98 g / L, nitric acid concentration 1.0 mol / L. According to the volume ratio, 10% extractant A and 90% sulfonated kerosene were prepared to prepare the extraction organic phase. The extraction organic phase and the iron-containing waste nitric acid solution were subjected to three-stage cross-current extraction at a ratio of O / A of 3:1. The extraction lasted for 10 minutes. 3+ The extraction rate is 100%, achieving the extraction of Fe in the iron-containing waste nitric acid solution. 3+ of extraction removal.

[0016] Comparative Example 1 This comparative example is basically the same as Example 1, except that: when extracting the organic phase, no extractant A is added, and the volume ratio is 100% sulfonated kerosene. 3+ Without extraction, it is impossible to achieve the Fe 3+ of extraction removal.

[0017] Comparative Example 2 This comparative example is basically the same as Example 1, except that no sulfonated kerosene was added when the organic phase was extracted, and 100% of the extractant A was used by volume. The organic phase was viscous and paste-like, and the extraction and mixing were difficult. 3+ Without extraction, it is impossible to achieve the Fe 3+ of extraction removal.

[0018] Comparative Example 3 This comparative example is basically the same as Example 2, except that: when extracting the organic phase, an organic phosphorus / phosphine extractant tributyl phosphate is used instead of extractant A, and the volume ratio is 20% tributyl phosphate and 80% sulfonated kerosene. 3+ Without extraction, it is impossible to achieve the Fe 3+ of extraction removal.

[0019] Comparative Example 4 This comparative example is basically the same as Example 3, except that: when extracting the organic phase, an organic phosphorus / phosphine extractant di(2,4,4-trimethylpentyl)phosphinic acid is used instead of extractant A, and the volume ratio is 20% di(2,4,4-trimethylpentyl)phosphinic acid and 80% sulfonated kerosene. 3+ The extraction rate was 29.98%, which was not enough to extract Fe from the iron-containing waste nitric acid solution. 3+ of extraction removal.

[0020] Comparative Example 5 This comparative example is basically the same as Example 4, except that the aqueous phase is selected to be an iron-containing waste sulfuric acid solution with the following composition: Fe 3+ 2.03 g / L, sulfuric acid concentration 6 mol / L. Fe 3+ The extraction rate is 67.63%, which is not possible to extract Fe from the iron-containing waste sulfuric acid solution. 3+ of extraction removal.

[0021] Comparative Example 6 This comparative example is basically the same as Example 4, except that the aqueous phase is selected from the iron-containing waste hydrochloric acid solution with the following composition: Fe 3+ 2.03 g / L, hydrochloric acid concentration 6 mol / L. Fe 3+ The extraction rate was 42.38%, which was not able to achieve the extraction of Fe 3+ of extraction removal.

[0022] Comparative Example 7 This comparative example is basically the same as Example 5, except that: when extracting the organic phase, an organic phosphorus / phosphine extractant di(2-ethylhexyl) phosphate is used instead of extractant A, and the volume ratio is 10% di(2-ethylhexyl) phosphate and 90% sulfonated kerosene. 3+ The extraction rate was 74.75%, which was not able to achieve the extraction of Fe in the iron-containing waste nitric acid solution. 3+ of extraction removal.

[0023] Comparative Example 8 This comparative example is basically the same as Example 5, except that: when extracting the organic phase, an organic phosphorus / phosphine extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester is used instead of extractant A, and the volume ratio is 10% 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester and 90% sulfonated kerosene. 3+ The extraction rate is 62.04%, which is not possible to extract Fe from the iron-containing waste nitric acid solution. 3+ of extraction removal.

[0024] Comparative Example 9 This comparative example is basically the same as Example 6, except that: when extracting the organic phase, an organic phosphorus / phosphine extractant trialkylphosphine oxide is used instead of extractant A, and the volume ratio is 10% trialkylphosphine oxide and 90% sulfonated kerosene. 3+ Without extraction, it is impossible to achieve the Fe 3+ of extraction removal.

[0025] By comparing the embodiments with the comparative examples, it can be seen that the Fe 3+ The extraction removal rates are far lower than those in the examples, which shows that the organic phase extracted by the mixed extraction agent A-sulfonated kerosene is used to extract and remove Fe in the nitric acid system. 3+ It is not a simple combination of extractants or similar replacement, but has unexpected and significant gain effects.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for extracting and removing iron from an iron-containing waste nitric acid solution, characterized in that: The method comprises the following steps: The iron-containing waste nitric acid solution is extracted with an extraction organic phase composed of an extractant A and sulfonated kerosene, and after phase separation, an iron-loaded organic phase and a nitric acid raffinate aqueous phase after iron removal are obtained; wherein the volume ratio of the extractant A to the sulfonated kerosene is 1-3:7-9; the chemical structural formula of the extractant A is as follows: ； The method is suitable for nitric acid concentration of 1.0~12mol / L, Fe 3+ The concentration of iron-containing waste nitric acid solution is 0.5~6 g / L. Within this concentration range, Fe 3+ The extraction rate is over 99.8%.

2. The method according to claim 1, characterized in that The extraction method is countercurrent or cross-current extraction; the extraction phase ratio O / A is 1~3:1; the extraction level is 1~3 levels; and the extraction time is 5~10min.

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