Method for removing fluorine and chlorine from brine

Abstract

The invention discloses a method for removing fluorine and chlorine from brine. The method comprises the following steps: adjusting the pH value of lepidolite leaching brine; preparing an extraction agent, and performing six-stage counter-current extraction through the extraction agent under a certain condition to extract the chlorine element and the fluorine element in the brine into the primary loaded organic liquid; carrying out three-stage countercurrent washing on the extracted loaded organic liquid in an acidic environment under certain conditions to obtain a secondary loaded organic liquid; the secondary loaded organic liquid is subjected to reverse extraction through ammonia water, reverse water is obtained, and no-load reverse extraction liquid obtained after reverse extraction can be mixed with an extraction agent for use; calcium oxide is added into the reverse water, and calcium fluoride filter residues and ammonium chloride filtrate are obtained after filter pressing. In the application, fluorine and chlorine in the brine are removed by performing six-stage countercurrent extraction, three-stage countercurrent washing and reverse extraction on the brine, so that the influence of fluorine and chlorine on the environment is reduced, the separation of fluorine and chlorine impurities in the brine at low operation cost is realized, and the technical bottleneck in the process of removing fluorine and chlorine from the brine is solved.

Description

Technical Field

[0001] The invention relates to a method for removing fluorine and chlorine from brine. Background Art

[0002] Lithium is the lightest metal among alkali metals. Lithium has important uses in the atomic energy industry. Lithium is often used in atomic reactors, light alloys and batteries. Metallic lithium can enter the human body through various pathways and be absorbed by organs and tissues, leading to lithium poisoning, which can cause central nervous system poisoning and kidney failure. As a new energy and strategic resource, lithium is known as "the energy metal that promotes world progress" and is the lightest metal known to date. Lithium is widely used in various fields due to its excellent electrochemical properties.

[0003] As an upstream product of most lithium products, lithium carbonate is widely used in glass, ceramics, metallurgy, chemical industry, electronics, medicine, battery and other industries because of its wide range of uses and outstanding advantages in energy storage equipment.

[0004] The brine produced by lithium carbonate contains relatively high levels of fluorine and chlorine, which has a great impact on the environment. The main methods for separating fluorine and chlorine include evaporation concentration, precipitation, solvent extraction, etc. Compared with precipitation and evaporation concentration, solvent extraction has low purification energy consumption, good separation effect, and easy automation and continuity of the production process. Currently, solvent extraction has become the main method used in industry.

[0005] In the prior art, CN102220480A is a method for removing fluorine and chlorine by roasting zinc oxide dust with microwaves, wherein the zinc oxide dust is roasted under microwave conditions, and after the temperature reaches 550-650°C, the temperature is kept for 10-30 minutes; the material is stirred during the roasting process; and the microwave cavity is evacuated to maintain normal pressure. Microwave roasting consumes a lot of energy and is difficult to industrialize.

[0006] CN101649396 provides a method for efficiently removing F and Cl by using zinc oxide ash, wherein the zinc oxide ash is added with dilute sulfuric acid solution for acidification and granulation, and then the F and Cl are removed by roasting in a rotary kiln, and the roasted powder is firstly neutrally leached, and the end point pH is controlled at 3.0-3.5, and the As, Sb and F contents of the leachate are detected at the end point, and FeSO4·7H2O is added to the leachate, and then hydrogen peroxide is added for oxidation and neutralization to remove As and Sb, and finally lime milk is added until the end point is detected to be free of Fe2+, As, Sb and F. The use of a rotary kiln for dechlorination has high energy consumption, large equipment maintenance, high investment and poor operating environment. Summary of the invention

[0007] The main purpose of the present invention is to provide a method for removing fluorine and chlorine from brine, aiming to provide a method for removing fluorine and chlorine from brine.

[0008] To achieve the above object, the present invention provides a brine defluorination and dechlorination method comprising:

[0009] Leaching the lepidolite into brine for pH adjustment;

[0010] An extractant is prepared and, under certain conditions, six-stage countercurrent extraction is performed by the extractant to extract chlorine and fluorine in the brine into a primary loaded organic liquid;

[0011] The loaded organic liquid after extraction is subjected to three-stage countercurrent washing in an acidic environment and under certain conditions to obtain a secondary loaded organic liquid;

[0012] The secondary loaded organic liquid is stripped by ammonia water to obtain stripping water, and the unloaded stripping liquid after stripping can be mixed with an extractant for use;

[0013] The backwater is added with calcium oxide and filtered to obtain calcium fluoride filter residue and ammonium chloride filtrate.

[0014] In one embodiment, the extractant is a mixture of two or more of trioctyldecyl tertiary amine, tributyl phosphate, trialkylamine, isooctyl alcohol, sulfonated kerosene and 260# solvent oil.

[0015] In one embodiment, the volume ratio of the three organic extractants, namely, trioctyldecyl tertiary amine, tributyl phosphate, trialkylamine, isooctyl alcohol, sulfonated kerosene and 260# solvent oil, is 2:1:7.

[0016] In one embodiment, the steps of preparing an extractant and extracting chlorine and fluorine in the brine into a primary loaded organic liquid by performing six-stage countercurrent extraction with the extractant under certain conditions are specifically as follows:

[0017] An extractant is prepared and six-stage countercurrent extraction is performed by the extractant under the conditions of a phase ratio of 1-10, a temperature of 0-45°C, an oscillation speed of 200-300 rpm, and an oscillation time of 0-10 min to extract chlorine and fluorine in the brine into a primary loaded organic liquid.

[0018] In one embodiment, the stripping conditions are: a ratio of 0.1-2, a temperature of 0-25° C., a shaking speed of 50-200 rpm, and a shaking time of 1-20 min.

[0019] In one embodiment, the ammonia water has a concentration of 5%-20%.

[0020] In one embodiment, the steps of performing three-stage countercurrent washing of the extracted loaded organic liquid in an acidic environment under certain conditions to obtain a secondary loaded organic liquid are specifically as follows:

[0021] The extracted loaded organic liquid is subjected to three-stage countercurrent washing in 0.5 mol / L dilute sulfuric acid to obtain a secondary loaded organic liquid.

[0022] In one embodiment, the conditions for the three-stage countercurrent washing are a phase ratio of 1-10, a temperature of 0-45° C., a shaking speed of 50-300 rpm, and a shaking time of 1-15 min.

[0023] In the technical solution of the present invention, the method for removing fluorine and chlorine from brine comprises:

[0024] Leaching the lepidolite into brine for pH adjustment;

[0025] An extractant is prepared and, under certain conditions, six-stage countercurrent extraction is performed by the extractant to extract chlorine and fluorine in the brine into a primary loaded organic liquid;

[0026] The loaded organic liquid after extraction is subjected to three-stage countercurrent washing in an acidic environment and under certain conditions to obtain a secondary loaded organic liquid;

[0027] The secondary loaded organic liquid is stripped by ammonia water to obtain stripping water, and the unloaded stripping liquid after stripping can be mixed with an extractant for use;

[0028] The backwater is added with calcium oxide and filtered to obtain calcium fluoride filter residue and ammonium chloride filtrate.

[0029] Therefore, in this technical solution, the fluorine and chlorine in the brine are removed by subjecting the brine to six-stage countercurrent extraction, three-stage countercurrent washing and stripping, thereby reducing the impact of fluorine and chlorine on the environment, achieving the separation of fluorine and chlorine impurities in the brine at a low operating cost, and solving the technical bottleneck in the process of removing fluorine and chlorine from the brine. At the same time, the by-product calcium fluoride can be used as an auxiliary agent in the building materials industry, and the by-product ammonium chloride solution can be used as a fertilizer in agriculture. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0032] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0033] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] The invention provides a method for removing fluorine and chlorine from brine.

[0035] The method for removing fluorine and chlorine from brine provided by the embodiment of the present invention comprises:

[0036] The pH of the brine leached from the lepidolite is adjusted to 0.5-2;

[0037] The extractant is configured and a six-stage countercurrent extraction is performed using a mixture of trioctyldecyl tertiary amine, tributyl phosphate, trialkylamine, isooctyl alcohol and 260# solvent oil under the conditions of a phase ratio of 1-10, a temperature of 0-45°C, an oscillation speed of 200-300 rpm and an oscillation time of 0-10 min to extract chlorine and fluorine in the brine into a primary load organic liquid;

[0038] The extracted loaded organic liquid is subjected to three-stage countercurrent washing under the conditions of 0.5 mol / L dilute sulfuric acid with a phase ratio of 1-10, a temperature of 0-45° C., an oscillation speed of 50-300 rpm, and an oscillation time of 1-15 min to obtain a secondary loaded organic liquid;

[0039] The secondary loaded organic liquid is stripped by 5%-20% concentration of ammonia water to obtain stripping water, and the unloaded stripping liquid after stripping can be mixed with the extractant for use;

[0040] The backwater is added with calcium oxide and filtered to obtain calcium fluoride filter residue and ammonium chloride filtrate.

[0041] In this embodiment, the fluorine and chlorine in the brine are removed by subjecting the brine to six-stage countercurrent extraction, three-stage countercurrent washing and stripping, thereby reducing the impact of fluorine and chlorine on the environment, achieving the separation of fluorine and chlorine impurities in the brine at a low operating cost, and solving the technical bottleneck in the process of removing fluorine and chlorine from the brine. At the same time, the by-product calcium fluoride can be used as an auxiliary agent in the building materials industry, and the by-product ammonium chloride solution can be used as a fertilizer in agriculture.

[0042] The present application is explained below based on a number of embodiments.

[0043] Example 1

[0044] The extractant composition is N235:TBP:260# solvent oil with a volume ratio of 2:2:6, a phase ratio of 1, a temperature of 20℃, an oscillation speed of 200rmp, and an oscillation time of 5min. When a six-stage countercurrent extraction is performed under the conditions, the fluorine extraction rate is 78.21% and the chlorine extraction rate is 81.02%. The loaded organic after extraction is washed with 0.5mol / L dilute sulfuric acid in a three-stage countercurrent manner, with a phase ratio of 10, a temperature of 20℃, an oscillation speed of 300rmp, and an oscillation time of 2min. Judging from the washing water, the fluorine elution rate is 0.08% and the chlorine elution rate is 0.11%. The washed loaded organic is stripped with 20% ammonia water. By back-calculating the fluorine and chlorine elements in the stripped water, it is known that the fluorine and chlorine stripping rates have reached more than 99%.

[0045] Example 2

[0046] The extractant composition is N235:TBP:260# solvent oil with a volume ratio of 2:1:7, a phase ratio of 0.5, a temperature of 20℃, an oscillation speed of 200rmp, and an oscillation time of 5min. When a six-stage countercurrent extraction is performed under the conditions, the fluorine extraction rate is 52.1% and the chlorine extraction rate is 68.7%. The loaded organic after extraction is washed with 0.5mol / L dilute sulfuric acid in a three-stage countercurrent manner, with a phase ratio of 10, a temperature of 20℃, an oscillation speed of 300rmp, and an oscillation time of 2min. Judging from the washing water, the fluorine elution rate is 0.1% and the chlorine elution rate is 0.14%. The washed loaded organic is stripped with 20% ammonia water. By back-calculating the fluorine and chlorine elements in the stripped water, it is known that the fluorine and chlorine stripping rates have reached more than 98%.

[0047] Example 3

[0048] The extractant composition is N235:TBP:260# solvent oil with a volume ratio of 2:1:7, a phase ratio of 1, a temperature of 20℃, an oscillation speed of 200rmp, and an oscillation time of 5min. When a six-stage countercurrent extraction is performed under the conditions, the fluorine extraction rate is 99.01% and the chlorine extraction rate is 99.03%. The loaded organic after extraction is subjected to three-stage countercurrent washing with 0.5mol / L dilute sulfuric acid, with a phase ratio of 10, a temperature of 20℃, an oscillation speed of 300rmp, and an oscillation time of 2min. Judging from the washing water, the fluorine elution rate is 0.04% and the chlorine elution rate is 0.05%. The washed loaded organic is stripped with 20% ammonia water. By back-calculating the fluorine and chlorine elements in the stripped water, it is known that the fluorine and chlorine stripping rates have reached more than 99%.

[0049] The present invention removes fluorine and chlorine from brine by subjecting brine to six-stage countercurrent extraction, three-stage countercurrent washing and stripping, and simultaneously extracts chlorine and fluorine to reduce environmental pollution. The reagent cost is low, and the byproducts after extraction can be recycled, further reducing costs.

[0050] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for removing fluorine and chlorine from brine, characterized in that: The method for defluorination and dechlorination of brine comprises: Leaching the lepidolite into brine for pH adjustment; An extractant is prepared and, under certain conditions, six-stage countercurrent extraction is performed by the extractant to extract chlorine and fluorine in the brine into a primary loaded organic liquid; The loaded organic liquid after extraction is subjected to three-stage countercurrent washing in an acidic environment and under certain conditions to obtain a secondary loaded organic liquid; The secondary loaded organic liquid is stripped by ammonia water to obtain stripping water, and the unloaded stripping liquid after stripping can be mixed with an extractant for use; The backwater is added with calcium oxide and filtered to obtain calcium fluoride filter residue and ammonium chloride filtrate.

2. The method for defluorination and dechlorination of brine according to claim 1, characterized in that: The extractant is a mixture of two or more of trioctyldecyl tertiary amine, tributyl phosphate, trialkylamine, isooctyl alcohol, sulfonated kerosene and 260# solvent oil.

3. The method for defluorination and dechlorination of brine according to claim 2, characterized in that: The volume ratio of the three organic extractants, namely, trioctyldecyl tertiary amine, tributyl phosphate, trialkylamine, isooctyl alcohol, sulfonated kerosene and 260# solvent oil, is 2:1:

7.

4. The method for defluorination and dechlorination of brine according to claim 1, characterized in that: The steps of preparing an extractant and extracting chlorine and fluorine in the brine into a primary loaded organic liquid by performing six-stage countercurrent extraction with the extractant under certain conditions are specifically as follows: An extractant is prepared and six-stage countercurrent extraction is performed by the extractant under the conditions of a phase ratio of 1-10, a temperature of 0-45°C, an oscillation speed of 200-300 rpm, and an oscillation time of 0-10 min to extract chlorine and fluorine in the brine into a primary loaded organic liquid.

5. The method for defluorination and dechlorination of brine according to claim 1, characterized in that: The stripping conditions are as follows: a ratio of 0.1-2, a temperature of 0-25° C., a shaking speed of 50-200 rpm, and a shaking time of 1-20 min.

6. The method for defluorination and dechlorination of brine according to claim 1, characterized in that: The ammonia water has a concentration of 5%-20%.

7. The method for defluorination and dechlorination of brine according to claim 1, characterized in that: The steps of performing three-stage countercurrent washing of the extracted loaded organic liquid in an acidic environment and under certain conditions to obtain a secondary loaded organic liquid are specifically as follows: The extracted loaded organic liquid is subjected to three-stage countercurrent washing in 0.5 mol / L dilute sulfuric acid to obtain a secondary loaded organic liquid.

8. The method for defluorination and dechlorination of brine according to claim 7, characterized in that: The conditions for the three-stage countercurrent washing are a phase ratio of 1-10, a temperature of 0-45°C, an oscillation speed of 50-300 rpm, and an oscillation time of 1-15 min.