CN112142068A - Method for producing high-purity ammonium chloride from industrial-grade ammonium chloride - Google Patents

Abstract

The invention discloses a method for producing high-purity ammonium chloride from industrial-grade ammonium chloride. The technical-grade ammonium chloride is used as a raw material, and firstly, the difference in solubility between ammonium chloride salt and other metal chloride salts at different temperatures and the solubility of Metal ions such as potassium, sodium, magnesium, iron, etc. are removed after two crystallization leaching, and then steam heated and concentrated to obtain ammonium chloride with higher purity. The treated ammonium chloride is then purified again by cation exchange resin, so that the metal ion content in ammonium chloride is less than 100ppb, which can be applied to electronic grade products. The yield of ammonium chloride in the treatment method of the present invention can reach 80-90%, and no new chemical substances are introduced in the treatment process, no new pollutants are brought to the original ammonium chloride system, and at the same time The collected eluent and the filtered mother liquor are collected, and finally low-grade ammonium chloride is obtained for fertilizer and other industries, and the application of resources is maximized.

Description

A kind of method for producing high-purity ammonium chloride from technical grade ammonium chloride

technical field

The invention relates to a method for purifying industrial-grade ammonium chloride, in particular to a method for removing metal ions of industrial-grade ammonium chloride.

Background technique

As an important source of nitrogen, ammonium chloride has important applications in agriculture and requires less metal ions. However, in the application of the electronic industry, the metal ions contained in it, such as potassium, sodium, calcium, magnesium, iron, etc., will have a great impact on the products of the applied industry.

At present, the methods for removing metal ions in ammonium chloride include organic solvent extraction, adding other chemical substances for chemical reaction and ion exchange.

The organic solvent extraction method and the addition of other chemical substances react to remove metal ions in ammonium chloride. This method introduces a new chemical substance, which is easy to cause pollution of the original system, and the waste water after the reaction is difficult to collect and treat, which puts great pressure on environmental protection.

The ion exchange method mainly removes potassium and sodium ions. First, the cation resin is treated to become an ammonium resin. The high potassium sodium ammonium chloride solution is passed through the ammonium resin to remove potassium and sodium ions in the solution. This method requires a large amount of solution regeneration. Resin, the amount of regenerated liquid waste water produced is large, which increases the cost of environmental protection treatment.

The above three methods not only generate waste liquid and cause a certain pressure to the environment, but also the metal ions in the treated ammonium chloride are still as high as 50ppm and above, which still cannot meet the requirements in the electronics industry and cannot be used directly.

SUMMARY OF THE INVENTION

In order to efficiently remove metal ions in industrial-grade ammonium chloride, the present invention aims to provide an environmentally friendly and effective method for removing metal ions. The ammonium chloride is purified by crystallization twice, and then the metal ions in the ammonium chloride after the crystallization treatment are removed by cation exchange resin to achieve further purification of the ammonium chloride, and the metal ions in the ammonium chloride can be removed to less than 100ppb.

A method for producing high-purity ammonium chloride by technical grade ammonium chloride, comprising the following steps:

(1) Dissolving technical grade ammonium chloride in deionized water at 60-90°C (preferably 80°C) can not only dissolve ammonium chloride to the maximum extent, but also widen the dissolving gap with sodium ions, and facilitate operation, Until the solution is saturated, a saturated ammonium chloride solution is obtained, and the solubility of ammonium chloride at 80°C is 65.6g/100g;

(2) the saturated ammonium chloride solution in step (1) is slowly cooled to make ammonium chloride crystallize;

(3) the ammonium chloride crystallized in the step (2) is kept at the crystallization temperature and filtered to obtain ammonium chloride crystals, and the ammonium chloride mother liquor obtained by filtration is collected to be treated;

(4) the ammonium chloride crystal obtained in the step (3) is rinsed with the eluent to obtain a higher purity ammonium chloride crystal for later use, and the eluent is collected for treatment; in order to rinse more thoroughly, the The obtained ammonium chloride crystals are dissolved and crystallized, and then rinsed again through the eluent to obtain ammonium chloride crystals with higher purity for use, and the eluent is collected for processing;

(5) dissolving the collected ammonium chloride crystals, through the exchange column of the cation resin, continue to remove the metal ions in the ammonium chloride, obtain a high-purity ammonium chloride solution, concentrate the obtained solution vapor, and dry to obtain high-purity chlorine Ammonium;

(6) the ammonium chloride mother liquor and the eluent vapour in steps (3), (4) and (5) are concentrated and dried to obtain a lower ammonium chloride product, which can be used in products such as fertilizers.

The content of metal ions in the ammonium chloride in the described step (1) is as shown in table 1, and in the technical grade ammonium chloride, sodium ions are up to more than 20000ppm, and metal ions such as potassium, magnesium and calcium are higher than more than 200ppm, and other such as iron. , manganese and other metal ions are also higher than 20ppm, which is far from meeting the requirements for applications in the wet electronic chemical industry.

Table 1 Content of metal ions in technical grade ammonium chloride

Analyzing the different solubility of different metal chlorides with temperature, it can be seen from Table 2 that the solubility of the main component ammonium chloride increases with temperature, while the solubility of sodium chloride changes relatively little with temperature, which can be efficiently removed by dissolving and crystallization. Sodium ions, while removing some other metals such as potassium, calcium, magnesium, aluminum, copper and other metals. In step (1), it is appropriate to choose 80 ° C. If the temperature is too high (such as above 100 ° C), it will cause the slow decomposition of ammonium chloride and reduce the yield of ammonium chloride. not obvious and difficult to separate).

Table 2 Solubility of different chlorides at different temperatures

In the step (2), the ammonium chloride solution was placed at room temperature at 80 ° C and slowly cooled down, when the temperature was consistent with room temperature, put into a low temperature constant temperature water bath, the temperature was lowered to 10-15 ° C, and the ammonium chloride was slowly crystallized, then Adjust the temperature of the low temperature constant temperature water bath to 0°C, continue to crystallize ammonium chloride, and reduce the temperature step by step, so that ammonium chloride can crystallize smoothly and gently, preventing the crystallization speed from being too fast, and the crystals entraining a large amount of metal, reducing the removal effect of metal ions .

In step (3), the filtration is carried out at the crystallization temperature, so as to avoid the reduction of the yield of ammonium chloride due to the dissolution of ammonium chloride caused by the temperature rise. The ammonium chloride solid obtained by filtration continues to be collected in a sand core funnel for subsequent processing, and the ammonium chloride mother liquor is collected in a clean container for subsequent use.

In step (4), the ammonium chloride solid in the sand core funnel is washed with saturated ammonium chloride solution, ice water at 0° C. or hydrochloric acid with a mass concentration of 36.5-37% to remove the metal entrapped in the ammonium chloride crystals. ions, collect the eluent for disposal.

In step (4), the temperature of the eluent is 10 to 40° C., and the elution time is 1 to 30 minutes.

Preferably, in step (4), the rinsing temperature is preferably 10-20°C, and the rinsing time is preferably 1-5 min. If the rinsing time is too short, the metal ion washing is incomplete, which affects the removal rate of metal ions. If the time is too long, part of the ammonium chloride will be dissolved and the yield of ammonium chloride will be reduced.

Through the treatment of the above steps (1) to (4), the obtained metal ions of the ammonium chloride product are shown in Table 3.

The content of metal ions in the crystalline ammonium chloride of table 3

The data in Table 3 shows that after two dissolution, crystallization and leaching treatments, the removal rate of sodium and potassium ions in ammonium chloride is relatively high, and other metal ions are lower than 100ppb, but for the wet electronic chemicals industry, when using , still need to be treated to continue to reduce the metal ion content.

In the step (5), the cation exchange resin is an ammonium type ion exchange resin, and the ammonium type ion exchange resin is converted from a 732 type hydrogen type ion exchange resin by adding ammonium chloride, through the sodium potassium magnesium in ammonium root and ammonium chloride, etc. Exchange of metal ions to remove metal ions in ammonium chloride.

Preferably, the volume ratio of ammonium chloride to 732-type hydrogen-type ion exchange resin when the hydrogen-type resin is converted into an ammonium-type resin in step (5) is 1-3:1.

In step (6), the collected ammonium chloride mother liquor and eluent are collected, and concentrated by steam to obtain low-grade ammonium chloride solids, which are used in the fertilizer industry without additional waste generation, and all resources are maximized use.

Through the treatment of the above steps, the yield of ammonium chloride can reach 80% to 90%.

Through the processing of the above steps, the metal ion content in the ammonium chloride is as shown in Table 4:

The content of metal ions in table 4 high-purity ammonium chloride

The advantages of the present invention are:

(1) the ammonium chloride crystal of the method of the present invention adopts saturated ammonium chloride to carry out leaching, not only can reduce the dissolving of the ammonium chloride crystal caused by the hot water flushing process, and the mother liquor collected is still ammonium chloride solution, can be It is collected and concentrated, dried and used as fertilizer, which reduces the production of by-products, reduces the pressure on environmental protection, and maximizes the use of resources.

(2) The method of the present invention passes the ammonium chloride after twice crystallization leaching through ammonium ion exchange resin, and deeply exchanges the metal ions in the ammonium chloride, so that the metal ion content can be removed to less than 100ppb, and the direct application to the wet electronic chemical industry.

(3) The method of the present invention does not introduce new chemical substances in the treatment process, and does not bring new pollutants to the original ammonium chloride system.

(4) The method of the present invention has a simple technical process and is easy to implement, and the yield of ammonium chloride can reach 80-90%, which can be widely used in industrial production.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The following embodiments are only exemplary and do not limit the content thereof.

Example 1

(1) Weigh 800g of deionized water, weigh 524.8g of technical grade ammonium chloride according to the solubility of ammonium chloride at 80°C, put the beaker containing deionized water and ammonium chloride in a constant temperature water bath and heat to 80 ℃, and kept stirring to completely dissolve the ammonium chloride to obtain a saturated ammonium chloride solution;

(2) place saturated ammonium chloride solution at room temperature and slowly lower the temperature to make ammonium chloride crystallize, when temperature reaches room temperature, put into low temperature constant temperature water bath and continue crystallization, until temperature reaches 5 ℃;

(3) the ammonium chloride crystallized in the step (2) is kept at the crystallization temperature and filtered through a sand core funnel to obtain ammonium chloride crystals, and the ammonium chloride mother liquor obtained by filtration is collected to be treated;

(4) rinsing the saturated ammonium chloride solution of the ammonium chloride crystal obtained in the step (3) at 5°C, the rinsing time is 1min, and the ammonium chloride crystal is collected;

(5) the ammonium chloride crystal obtained in the step (4) is slowly heated and dissolved according to the method of the step (1), then the temperature is slowly lowered at room temperature, and the ammonium chloride is crystallized, and after the temperature reaches room temperature, put into a low temperature constant temperature Continue to cool and crystallize in a water bath until the temperature reaches 5°C;

(6) rinsing the saturated ammonium chloride solution of the ammonium chloride crystal obtained in the step (5) at 5°C, the rinsing time is 1min, and the ammonium chloride crystal is collected;

(7) The collected ammonium chloride crystals are concentrated with pure hot air and dried to obtain high-purity ammonium chloride.

Example 2

The steps are the same as in Example 1, except that the rinsing time in steps (4) and (6) is 3min.

Example 3

The steps are the same as in Example 1, except that the rinsing time in steps (4) and (6) is 5min.

Example 4

The steps are the same as in Example 3, except that the crystallization temperature in step (2) is 15°C, and the ammonium chloride crystals in steps (4) and (6) are rinsed with saturated ammonium chloride solution at 15°C.

Example 5

The steps are the same as in Example 3, except that the crystallization temperature in step (2) is 20°C, and the ammonium chloride crystals in steps (4) and (6) are rinsed with saturated ammonium chloride solution at 20°C.

Example 6

The steps are the same as those in Example 3, except that in steps (4) and (6), the ammonium chloride crystals are rinsed with a 37% high-purity hydrochloric acid solution at 5°C.

Example 7

The steps are the same as in Example 3, except that in steps (4) and (6), the ammonium chloride crystals are rinsed in ice water at 0°C.

Example 8

Step is the same as Example 3, only step (7) is to dissolve the collected ammonium chloride crystals to carry out ion exchange through ammonium type ion exchange resin (the volume ratio of 732 type hydrogen type ion exchange resin and ammonium chloride is 1:1), Continue to remove metal ions in the ammonium chloride to obtain a high-purity ammonium chloride solution, and vapor-concentrate and dry the obtained solution to obtain high-purity ammonium chloride.

Example 9

Step is the same as Example 3, only step (7) is to dissolve the collected ammonium chloride crystals to carry out ion exchange through ammonium type ion exchange resin (the volume ratio of 732 type hydrogen type ion exchange resin and ammonium chloride is 2:1), Continue to remove metal ions in the ammonium chloride to obtain a high-purity ammonium chloride solution, and vapor-concentrate and dry the obtained solution to obtain high-purity ammonium chloride.

Example 10

Step is the same as Example 3, only step (7) is to dissolve the collected ammonium chloride crystals to carry out ion exchange through ammonium type ion exchange resin (the volume ratio of 732 type hydrogen type ion exchange resin and ammonium chloride is 3:1), Continue to remove metal ions in the ammonium chloride to obtain a high-purity ammonium chloride solution, and vapor-concentrate and dry the obtained solution to obtain high-purity ammonium chloride.

The indexes corresponding to the above-mentioned embodiments 1-10 of the present invention are shown in Table 5:

table 5

From the results of the above example, it can be seen that the 5min leaching time is compared with 1min, which can not only eluate the metal ions to a level that meets the requirements of use, but also can effectively control the amount of leaching. The ions are lower and the yields vary less.

From the above data analysis, it can be seen that after two crystallization washings, the metal content has changed by changing the leaching time. With the prolongation of rinsing time, the removal rate of metal ions adhering to the crystal surface increases, and if the cleaning time is too long, the required amount of rinsing solution increases, increasing the environmental protection pressure. The appropriate leaching time is 5 minutes, which can not only eluate the metal ions to a level that meets the requirements of use, but also effectively control the amount of leaching. The temperature of the eluent is controlled at 5-20°C. If the temperature is too low, more power is needed to reduce the temperature of the eluent to the applicable range. If the temperature is too high, some crystals will dissolve during the elution process, reducing the yield of ammonium chloride. Rate.

The ammonium chloride that has been washed twice by crystallization is subjected to cation exchange through ammonium resin, which can reduce the content of metal ions in ammonium chloride to a greater extent. When the volume ratio of ammonium chloride to hydrogen cation exchange resin is 2:1 When ammonium chloride is used, it can reach below 100ppb, and the yield is as high as 90.6%. Continue to increase the volume of ammonium chloride to convert the hydrogen-type cation exchange resin into ammonium-type resin, and the purification effect of ammonium chloride is no longer significantly improved. The volume ratio of ammonium to hydrogen cation exchange resin is 2:1.

The method for producing high-purity ammonium chloride from technical-grade ammonium chloride of the present invention has been described in detail above. The above are only specific embodiments of the present invention, and are not intended to limit the protection scope of the present invention. On the basis of the present invention, Some modifications or improvements may be made to it, as will be apparent to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention fall within the scope of the claimed protection of the present invention.

Claims (7)

1. a method for producing high-purity ammonium chloride from technical grade ammonium chloride, is characterized in that, comprises the following steps: (1) Dissolve technical grade ammonium chloride in deionized water at 60-90°C until the solution reaches saturation; (2) cooling the saturated ammonium chloride solution in step (1) for crystallization to obtain ammonium chloride crystalline product; (3) the ammonium chloride crystallization product in step (2) is filtered while maintaining the crystallization temperature to obtain ammonium chloride crystals, and the ammonium chloride mother liquor obtained by filtration is collected for processing; (4) rinsing the ammonium chloride crystals obtained in step (3) through the eluent to obtain ammonium chloride crystals; (5) Dissolving the collected ammonium chloride crystals again, and passing through the exchange column of the cation resin, the obtained ammonium chloride solution is steam concentrated and dried to obtain ammonium chloride with a metal ion impurity content of less than 100ppb. 2. the method for producing high-purity ammonium chloride according to the technical grade ammonium chloride described in claim 1, is characterized in that, the metal ion impurity in the technical grade ammonium chloride in step (1) comprises sodium ion, potassium ion , magnesium ions, and calcium ions, wherein the content of sodium ions is more than 20,000 ppm, and the content of potassium ions, magnesium ions, and calcium ions is more than 200 ppm, respectively. 3. the method for producing high-purity ammonium chloride according to technical grade ammonium chloride described in claim 1, is characterized in that, In step (2), the saturated ammonium chloride solution is crystallized at a temperature of 0-15°C. 4. the method for producing high-purity ammonium chloride according to the technical grade ammonium chloride described in claim 1, is characterized in that, when step (3) is filtration, under vacuum degree is 0.06～0.08Mpa to carry out suction filtration. 5. the method for producing high-purity ammonium chloride according to the technical grade ammonium chloride described in claim 1, is characterized in that, the eluent described in step (4) is the concentrated hydrochloric acid that mass concentration is 36.5-37% , ice water at 0°C or saturated ammonium chloride solution. 6. the method for producing high-purity ammonium chloride according to the technical grade ammonium chloride described in claim 1, is characterized in that, in step (4), the temperature of eluent is 10～15 ℃; The eluent time is 1～30min . 7. The method for producing high-purity ammonium chloride from industrial grade ammonium chloride according to claim 1, wherein the exchange column of the cation resin described in the step (5) is an ammonium type ion exchange resin and is a 732 type Hydrogen ion exchange resin is obtained by adding ammonium chloride, and the volume ratio of ammonium chloride to 732 hydrogen ion exchange resin is 1~3:1.