阅读说明：本技术 一种从盐酸法湿法磷酸溶液中萃取氯离子的方法 (Method for extracting chloride ions from wet-process phosphoric acid solution by hydrochloric acid method ) 是由 曾钢兴 丁一刚 龙秉文 邓伏礼 张逸 戴亚芬 余莹 居丽 梁蕾 杜治平 刘生鹏 于 2021-02-04 设计创作，主要内容包括：本发明公开了一种从盐酸法湿法磷酸中萃取氯离子的方法,其步骤为：将适量破乳剂加入盐酸法湿法磷酸溶液中搅拌混合进行预处理,将三辛胺和正辛醇混合组成萃取有机相加入到预处理后的湿法磷酸溶液中进行萃取,萃余液直接用于浓缩制备工业级磷酸；最后用氨水溶液对萃取后的有机相进行反萃,反萃后的有机相返回到预处理后的湿法磷酸溶液中循环使用。该方法适用于盐酸法制备工业磷酸中氯离子的萃取分离,对氯离子有很高的选择性,有机相可重复使用,减少了磷酸损失,并大大降低生产成本,在相对简单的实验条件下,实现了盐酸法湿法磷酸溶液中氯离子的有效分离,得到高纯度的磷酸。(The invention discloses a method for extracting chloride ions from wet-process phosphoric acid by a hydrochloric acid method, which comprises the following steps: adding a proper amount of demulsifier into the wet-process phosphoric acid solution by a hydrochloric acid method, stirring and mixing for pretreatment, mixing trioctylamine and n-octanol to form an extraction organic phase, adding the extraction organic phase into the pretreated wet-process phosphoric acid solution for extraction, and directly using raffinate for concentrating to prepare industrial-grade phosphoric acid; and finally, carrying out back extraction on the extracted organic phase by using an ammonia solution, and returning the back-extracted organic phase to the pretreated wet-process phosphoric acid solution for recycling. The method is suitable for extracting and separating chloride ions in the industrial phosphoric acid prepared by the hydrochloric acid method, has high selectivity on the chloride ions, can repeatedly use an organic phase, reduces the loss of phosphoric acid, greatly reduces the production cost, and realizes the effective separation of the chloride ions in the phosphoric acid solution by the hydrochloric acid method and the wet method under relatively simple experimental conditions to obtain the high-purity phosphoric acid.)

1. A method for extracting chloride ions from wet-process phosphoric acid by a hydrochloric acid method is characterized by comprising the following steps:

1) pretreatment: adding a proper amount of demulsifier into the wet-process phosphoric acid solution by the hydrochloric acid method, stirring and mixing to obtain a pretreated wet-process phosphoric acid solution;

2) mixing trioctylamine and n-octanol to form an extraction organic phase, adding the extraction organic phase into the pretreated wet-process phosphoric acid solution obtained in the step 1) for extraction, and directly using raffinate for concentrating to prepare industrial-grade phosphoric acid;

3) and (3) carrying out back extraction on the extracted organic phase obtained in the step 2) by using an ammonia solution, and returning the obtained back extraction organic phase to the step 2) for recycling.

2. The method for extracting chloride ions according to claim 1, wherein the volume ratio of trioctylamine to n-octanol in the extracted organic phase of step 2) is (1-3): 1.

3. the method for extracting chloride ions according to claim 1, wherein the demulsifier in step 1) is one or more of cetyl trimethyl ammonium bromide, sodium dodecyl benzene sulfonate, sodium lauryl sulfate, AEO-9 and OP-30.

4. The method for extracting chloride ions according to claim 3, wherein the demulsifier is a mixture of 1: (0.5-2) a compound mixture of cetyl trimethyl ammonium bromide and sodium lauryl sulfate.

5. The method for extracting chloride ions according to claim 1, wherein the demulsifier is added in an amount of 0.025-0.08% by mass based on the hydrochloric acid wet-process phosphoric acid solution in the step 1).

6. The method for extracting chloride ions according to claim 1, wherein in the step 1), the demulsifier is added into the hydrochloric acid wet-process phosphoric acid solution and stirred for 10-15 min for mixing.

7. The method for extracting chloride ions according to claim 1, wherein the ratio of the organic phase to the hydrochloric acid wet process phosphoric acid solution in the step 2) is (0.5-3): 1, the extraction time is 20-60 min, the extraction temperature is 20-50 ℃, and the phase separation time is 10-20 min.

8. The method for extracting chloride ions according to claim 1, wherein the back extraction ratio of the organic phase to the aqueous phase ammonia solution is (0.5-3): 1, the back extraction time is 20-60 min, the back extraction temperature is 20-50 ℃, and the phase separation time is 10-20 min.

9. The method for extracting chloride ions according to claim 1, wherein in the step 3), the ammonia water is an ammonia water solution with a mass fraction of 5-15%.

10. The method for extracting chloride ions according to claim 1, wherein the mass fraction of chloride ions in the hydrochloric acid wet-process phosphoric acid solution is 14-21%, and the mass fraction of phosphorus pentoxide is 8-10%.

Technical Field

The invention belongs to the technical field of wet-process phosphoric acid by a hydrochloric acid method, and particularly relates to a method for extracting chloride ions from a wet-process phosphoric acid solution by the hydrochloric acid method.

Background

The production process of the wet-process phosphoric acid is simpler, the universality is better, the key is that the requirement on the grade of the phosphorite is not high, and the wet-process phosphoric acid is more suitable for the medium and low grade phosphorite. Therefore, wet-process phosphoric acid has now become the dominant phosphoric acid production process. Because the inorganic acid selected in the wet-process phosphoric acid production process is different, the production process can be divided into three processes, namely a hydrochloric acid process, a nitric acid process and a sulfuric acid process, wherein the sulfuric acid process is the mainstream process in the current wet-process phosphoric acid industry, and the method is mature in industrial application and is suitable for low-grade phosphate ores. Although the sulfuric acid method has simple process and low energy consumption, the method has the following defects: (1) the production needs to consume a large amount of H₂SO₄The sulfur resource in China is short, most of sulfur depends on import, and therefore, the production cost is increased; (2) the production of one ton of phosphoric acid yields about 4.5 tons of phosphogypsum, and the treatment and utilization of phosphogypsum are difficult.

The hydrochloric acid process can eliminate phosphogypsum from the root. At present, phosphoric acid is mainly produced by a sulfuric acid method in China, severe environmental burden is caused by phosphogypsum stockpiling, and the treatment pressure of the phosphogypsum is increased greatly day by day. With the increasing importance of the country on the ecological environment, the limitation on the sulfuric acid process is larger and larger. The hydrochloric acid method refers to a method for preparing phosphoric acid by decomposing phosphorite with hydrochloric acid. The hydrochloric acid raw material has wide sources and is a byproduct of a plurality of process flows; the hydrochloric acid has a plurality of purposes for decomposing the phosphorite by-products, and is favorable for recovering associated rare earth elements of the phosphorite due to good solubility of the hydrochloric acid. In general, the hydrochloric acid method has relatively small pollution to the environment, is suitable for middle-low grade phosphorite and is suitable for the situation of China, so the hydrochloric acid method has certain development advantages. However, the wet-process phosphoric acid prepared by the hydrochloric acid method contains a large amount of chloride ions, and the pure phosphoric acid can be obtained only by separating the chloride ions, and since the last century, phosphoric acid and chloride ions are mostly separated by extracting phosphoric acid at home and abroad, and no method for achieving the separation effect by extracting chloride ions is found in the prior art.

In recent years, the solvent extraction research of chloride ions in China mainly focuses on the extraction separation of hydrochloric acid, nitric acid, phosphoric acid and sulfuric acid, the used extracting agents mainly comprise amine extracting agents and neutral extracting agents, for example, Chenyinhua and the like are reported to use toluene and isooctanol as diluents, TOA (trioctylamine) as extracting agents, the research on the extraction separation of derusting waste hydrochloric acid of a certain cold-rolled steel plate factory is carried out, and the hydrochloric acid extraction effect is good when 30% of TOA, 60% of toluene and 10% of isooctanol (all in volume percentage). However, the method is used for decomposing phosphorite with hydrochloric acid to generate a phosphoric acid complex solution system with lower concentration, serious emulsification is easily generated in the extraction process, phase separation is difficult to realize, and organic phase loss is caused. The Euro-Yang mussel and the like also report the extraction and separation of hydrochloric acid by a neutral extractant, which is characterized in that isoamyl alcohol is used as the extractant to extract and separate phosphoric acid and hydrochloric acid in a chloride phosphoric acid system, the extraction effect of the hydrochloric acid at high concentration is good, and the extraction effect of the hydrochloric acid at low concentration is poor. Chinese patent CN 2016105112591' a method for preparing purified phosphoric acid from phosphorite, is characterized in that at least one of DNNSA, P204, P507, Cyanex272, naphthenic acid and versatic acid is used as an extracting agent, a diluent is sulfonated kerosene or cyclohexane, the content of chloride ions in the obtained purified phosphoric acid exceeds the standard, the quality of the product is reduced, the product cannot be directly used as industrial phosphoric acid, and the purification is still required. Chinese patent CN201610686625.7 "an extractant for preparing industrial phosphoric acid by hydrochloric acid method and its extraction method" is characterized in that the extractant is prepared by mixing tributyl phosphate, n-butanol, isopropanol, n-butyl ether, isopropyl ether, high carbon ketone, fatty amine, hexadecyl trimethyl ammonium chloride, oil-based polyoxyethylene ether sulfonate and other substances, and phosphoric acid and chloride ions are purified and separated by extracting phosphoric acid. However, the whole process is complicated by complex operations such as multi-stage extraction and acid washing, and the extractant loss is large.

Wet-process phosphoric acid products such as phosphoric acid for preparing phosphate fertilizer or feed and the like have the defects that if the chlorine content exceeds the standard, vegetation and crop growth are influenced inevitably, so that part of crops cannot synthesize protein, the vegetation and normal growth of the crops are damaged, and most of crops and vegetation are poisoned and killed, so that the method for separating the chloride ions in the hydrochloric acid wet-process phosphoric acid solution by a simple method is urgent.

Disclosure of Invention

The invention aims to provide a method for extracting chloride ions from a hydrochloric acid wet-process phosphoric acid solution aiming at the defects in the prior art. The method is suitable for extracting and separating chloride ions in the industrial phosphoric acid prepared by the hydrochloric acid method, has high selectivity on the chloride ions, extracts the chloride ions and a small amount of phosphoric acid by using a solvent extraction method, can back extract the chloride ions from an extracted organic phase through back extraction, retains the phosphoric acid in the organic phase, can repeatedly extract the organic phase, reduces the phosphoric acid loss, greatly reduces the production cost, and realizes the effective separation of the chloride ions in the phosphoric acid solution prepared by the hydrochloric acid method and the wet method under relatively simple experimental conditions to obtain the high-purity phosphoric acid.

In order to achieve the purpose, the invention adopts the following technical scheme:

provides a method for extracting chloride ions from wet-process phosphoric acid by a hydrochloric acid method, which comprises the following steps:

1) pretreatment: adding a proper amount of demulsifier into the wet-process phosphoric acid solution by the hydrochloric acid method, stirring and mixing to obtain a pretreated wet-process phosphoric acid solution;

2) mixing trioctylamine and n-octanol to form an extraction organic phase, adding the extraction organic phase into the wet-process phosphoric acid solution pretreated in the step 1) for extraction, and directly using raffinate for concentrating to prepare industrial-grade phosphoric acid;

3) and (3) performing back extraction on the extracted organic phase obtained in the step 2) by using an ammonia solution, so that chloride ions in the organic phase are transferred into the water phase again, and the obtained back-extracted organic phase is returned to the step 2) for recycling.

According to the scheme, in the step 1), the demulsifier is one or more of cetyl trimethyl ammonium bromide, sodium dodecyl benzene sulfonate, sodium lauryl sulfate, AEO-9 and OP-30; the preferable mass ratio is 1: (0.5-2) a compound mixture of cetyl trimethyl ammonium bromide and sodium lauryl sulfate.

According to the scheme, in the step 1), the addition amount of the demulsifier is 0.025-0.08% of the wet-process phosphoric acid solution by a hydrochloric acid method according to mass percentage.

According to the scheme, in the step 1), the demulsifier is added into the wet-process phosphoric acid solution by the hydrochloric acid method, and is stirred for 10-15 min for mixing.

According to the scheme, in the step 2), in the organic phase of extraction, the volume ratio of the trioctylamine to the n-octanol is (1-3): 1.

according to the scheme, in the step 2), the ratio of the organic phase to the wet-process phosphoric acid solution by a hydrochloric acid method is (0.5-3): 1, the extraction time is 20-60 min, the extraction temperature is 20-50 ℃, and the phase separation time is 10-20 min.

According to the scheme, in the step 3), the ammonia water is an ammonia water solution with the mass fraction of 5-15%.

According to the scheme, in the step 3), the back extraction ratio of the organic phase to the aqueous phase ammonia water solution is (0.5-3): 1, the back extraction time is 20-60 min, the back extraction temperature is 20-50 ℃, and the phase separation time is 10-20 min.

According to the scheme, the mass fraction of chloride ions in the phosphoric acid solution obtained by the hydrochloric acid wet process is 14-21%, and the mass fraction of phosphorus pentoxide is 8-10%.

Compared with the prior art, the invention has the beneficial effects that:

1. the method comprises the steps of adding a demulsifier into a hydrochloric acid wet-process phosphoric acid solution for pretreatment, then taking trioctylamine and n-octanol as extraction organic phases, directly extracting chloride ions and a small amount of phosphoric acid by using a solvent extraction method, directly concentrating raffinate to prepare industrial-grade phosphoric acid, back-extracting the chloride ions from the extracted organic phases by back-extraction, retaining the phosphoric acid in the organic phases, repeatedly using the back-extracted organic phases for extraction of the hydrochloric acid wet-process phosphoric acid solution, reducing the phosphoric acid loss, greatly reducing the production cost, and realizing effective separation of the chloride ions in the hydrochloric acid wet-process phosphoric acid solution under relatively simple experimental conditions to obtain the high-purity phosphoric acid.

2. The invention reduces the emulsification phenomenon in the extraction process by adding the demulsifier, thereby reducing the loss of organic phase and further improving the extraction effect of chloride ions.

3. The method has the advantages of simple equipment in the whole process, short process flow, energy conservation, environmental protection, good effect, no need of pickling, back extraction and other operations on the extracted phosphoric acid, reusability of the extracted organic phase, great saving of production cost, reduction of phosphoric acid loss and suitability for large-scale application.

Detailed Description

In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.

Example 1

The wet method for treating hydrochloric acid is adopted to prepare the phosphoric acid solution, the solution is a solution pretreated by a certain factory, and the components of the solution are as follows by mass percent: the content of chloride ions is 14.94 percent, the content of phosphorus pentoxide is 9.17 percent, sodium lauryl sulfate is used as a demulsifier and is added into the phosphoric acid solution prepared by the hydrochloric acid wet method for pretreatment, and the adding amount is 0.025 percent of the mass of the phosphoric acid solution prepared by the hydrochloric acid wet method. Adding an extraction organic phase consisting of trioctylamine and n-octanol in a volume ratio of 2.5:1 into the pretreated hydrochloric acid wet-process phosphoric acid solution, extracting for 40min under the condition that the extraction temperature is 25 ℃ and the ratio of the extraction organic phase to the aqueous phase hydrochloric acid wet-process phosphoric acid solution is 2:1, standing for phase separation for 20min, allowing chloride ions in the phosphoric acid solution and a small amount of phosphoric acid to enter the organic phase, measuring the extraction dechlorination rate according to the national standard GB/T24890-2010 and measuring the extraction rate of phosphorus pentoxide according to the national standard GB/T23843-2009 to be 18.43%. The separation coefficient of chloride ions from phosphorus pentoxide was 4.91.

The organic phase contains 7.86 percent of chlorine and 1.69 percent of phosphorus pentoxide, and is back-extracted by an ammonia water solution with the mass fraction of 10 percent, and the back-extraction conditions are as follows: the phase ratio of the back extraction organic phase to the aqueous phase ammonia water solution is 2:1, the back extraction temperature is 25 ℃, the back extraction time is 40min, the phase separation time is 20min, the back extraction dechlorination rate is 89.32% according to the national standard GB/T24890-2010, and the organic phase obtained by back extraction can be repeatedly used for extracting chloride ions from the pretreated hydrochloric acid wet-process phosphoric acid solution.

Example 2

The solution is pretreated in a certain factory and comprises the following components in percentage by mass: the content of chloride ions is 17.21 percent, and the content of phosphorus pentoxide is 9.13 percent. Cetyl trimethyl ammonium bromide is used as a demulsifier, hydrochloric acid wet-process phosphoric acid solution is added for pretreatment, the addition amount is 0.025 percent of the mass of the hydrochloric acid wet-process phosphoric acid solution, an extraction organic phase consisting of trioctylamine and n-octanol with the volume ratio of 2.5:1 is added into the pretreated hydrochloric acid wet-process phosphoric acid solution, the extraction temperature is 25 ℃, the extraction organic phase is extracted for 40min under the condition that the comparison ratio of the extraction organic phase to the aqueous phase hydrochloric acid wet-process phosphoric acid solution is 2:1, then the standing phase separation is carried out for 20min, chloride ions in the phosphoric acid solution and a small amount of phosphoric acid enter the organic phase, the extraction dechlorination rate is 58.74 percent according to the national standard GB/T24890-2010, and the extraction rate of phosphorus pentoxide is 15.77 percent according to the national standard GB/T23843-2009. The separation coefficient of chloride ions from phosphorus pentoxide was 7.60.

The organic phase contains 10.11 percent of chlorine and 1.44 percent of phosphorus pentoxide, and is back-extracted by an ammonia water solution with the mass fraction of 10 percent, and the back-extraction conditions are as follows: the phase ratio of the back extraction organic phase to the aqueous phase ammonia water solution is 3:1, the back extraction temperature is 30 ℃, the back extraction time is 40min, the phase separation time is 20min, the back extraction dechlorination rate is 90.12% according to the national standard GB/T24890-2010, and the organic phase obtained by back extraction can be repeatedly used for extracting chloride ions from the pretreated hydrochloric acid wet-process phosphoric acid solution.

Example 3

The invention is used for treating phosphoric acid solution by a hydrochloric acid wet process, and the solution comprises the following components in percentage by mass: the content of chloride ions is 20.33 percent, the content of phosphorus pentoxide is 9.86 percent, and the mass ratio of hexadecyl trimethyl ammonium bromide to sodium lauryl sulfate is 1: 1 mixing the raw materials to be used as a demulsifier, adding the demulsifier into a phosphoric acid solution prepared by a hydrochloric acid wet method for pretreatment, wherein the adding amount of the demulsifier is 0.074 percent of the mass of the phosphoric acid solution prepared by the hydrochloric acid wet method. Adding an extraction organic phase consisting of trioctylamine and n-octanol in a volume ratio of 2.5:1 into the pretreated hydrochloric acid wet-process phosphoric acid solution, extracting for 40min under the condition that the extraction temperature is 25 ℃ and the ratio of the extraction organic phase to the aqueous phase hydrochloric acid wet-process phosphoric acid solution is 2:1, standing for phase separation for 20min, allowing chloride ions in the phosphoric acid solution and a small amount of phosphoric acid to enter the organic phase, measuring the extraction dechlorination rate according to the national standard GB/T24890-2010, and measuring the extraction rate of phosphorus pentoxide according to the national standard GB/T23843-2009 to be 16.33%. The separation coefficient of chloride ions from phosphorus pentoxide was 10.95.

The organic phase contains 13.85 percent of chlorine and 1.61 percent of phosphorus pentoxide, and is back-extracted by an ammonia water solution with the mass fraction of 10 percent, and the back-extraction conditions are as follows: the phase ratio of the back extraction organic phase to the aqueous phase ammonia water solution is 3:1, the back extraction temperature is 40 ℃, the back extraction time is 40min, the phase separation time is 20min, the back extraction dechlorination rate is 95.00% according to the national standard GB/T24890-2010, and the organic phase obtained by back extraction can be repeatedly used for extracting chloride ions from the pretreated hydrochloric acid wet-process phosphoric acid solution.