CN217367229U - Device of layer type integral crystallization purification silver nitrate - Google Patents
Device of layer type integral crystallization purification silver nitrate Download PDFInfo
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- CN217367229U CN217367229U CN202221199381.7U CN202221199381U CN217367229U CN 217367229 U CN217367229 U CN 217367229U CN 202221199381 U CN202221199381 U CN 202221199381U CN 217367229 U CN217367229 U CN 217367229U
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Abstract
The utility model discloses a device for purifying silver nitrate by layer type integral crystallization, which comprises a heat exchange crystallizer, wherein a feed pipeline, a pure water feed pipeline and a circulating pipeline are connected with the inlet of the heat exchange crystallizer; the heat exchange crystallizer consists of a tube pass and a shell pass, and a distributor is arranged in the heat exchange crystallizer; the shell pass of the heat exchange crystallizer is connected with a heat exchange medium inlet pipeline and a heat exchange medium outlet pipeline; a discharge pipeline of the heat exchange crystallizer is communicated with an inlet of a high-purity silver nitrate storage tank or a mother liquor storage tank through valve switching; the outlet of the high-purity silver nitrate storage tank is connected with a product pump and a product discharge pipeline; the outlet of the mother liquor storage tank is connected with a material circulating pump, and the material circulating pump is switched by a valve to be communicated with a circulating pipeline or a mother liquor pipeline. The device system structure is changed, the device is applied to a purification process of silver nitrate solution, and pure water is used for dissolving silver nitrate crystals to prepare high-purity silver nitrate solution. The utility model discloses the device heat transfer area is big, and crystallization efficiency is high, and the high-purity silver nitrate purity of preparation can reach the photographic grade.
Description
Technical Field
The utility model belongs to the technical field of silver nitrate solution saturated crystallization purification, concretely relates to device of whole crystallization purification silver nitrate of layer formula.
Background
Silver nitrate is used as a silver chemical product, is a production raw material and a foundation of other silver high-value-added products, and has wide application in the fields of mirror making, medicine, electroplating, superfine silver powder and the like. With the improvement of the product quality requirements of downstream industries, silver nitrate gradually develops towards high purification.
At present, the main method for preparing high-purity silver nitrate is a reaction process of adding nitric acid to dissolve silver, and then silver nitrate crystals are obtained through processes of impurity removal, filtration, evaporation, concentration, crystallization, centrifugation, drying, packaging and the like. In order to obtain high-purity silver nitrate, the silver nitrate solution needs to be purified and decontaminated to remove solid impurities and metal impurity ions such as copper, iron, nickel and the like. In principle, solid impurities are removed by filtration, and metal impurity ions are removed by adding an impurity removing agent or removing impurities at high temperature, so that a silver nitrate product meets the high-purity requirement. At present, most of production and preparation processes are low in purification and impurity removal efficiency.
In addition, crystallization is another important silver nitrate purification means. Patent publication No. CN111732120A discloses an environment-friendly and efficient production method of high-purity silver nitrate, which comprises the steps of firstly obtaining a silver nitrate solution through the reaction of silver ingots and nitric acid, then purifying the silver nitrate solution, and then sequentially carrying out reduced-pressure and efficient evaporation, efficient crystallization, solid-liquid separation, drying, crushing and packaging. The crystallization process in the patent is a crystallization method of a conventional crystallization tank, and the silver nitrate solid-liquid mixture is transferred into the crystallization tank filled with chilled water for crystallization. The crystallization process is difficult to remove the mother liquor occluded in the crystals and in the gaps among the crystals, and the occluded mother liquor after the crystallization is just an important factor influencing the purification process of the crystals.
Layer-wise melt crystallization is used in the crystallization process after melting of organic matter, the crystals grow rapidly on a cooled surface, wherein undercooling is provided by the crystallization layer; the remaining melt or residual liquid is discharged from the solid layer and the finally purified crystalline solid is discharged after melting. Patent publication No. CN113831231A discloses a method for preparing ultra-pure 2,4' -difluorobenzophenone by melt crystallization, which adopts a melt crystallization mode for purification, can purify to obtain 99.9 percent or even over 99.99 percent of ultra-pure products, has the advantages of no solvent addition, safe process, no three wastes, high product purity and the like, and is a green separation and purification process. Patent publication No. CN113896627A provides a method for preparing high-purity chloroacetic acid by layered melt crystallization. The method comprises the following steps: 1) preheating and melting materials; 2) cooling and crystallizing;
3) heating to sweat and 4) melting and discharging materials. Patent publication No. CN203677985U discloses an apparatus for preparing high-purity organic matter, and particularly relates to an apparatus for purifying organic matter by adopting a melt crystallization mode.
The melt crystallization is a process for obtaining the target product in the process of cooling crystallization after melting of materials, and is difficult to be used for melt crystallization of most inorganic compounds due to the melt process involved for crystallization purification of organic substances, thereby limiting the application range. In addition, a unique purification process of sweating to discharge residual liquid occluded in crystals is used in the melt crystallization process, but the application is difficult due to the high melting point of the inorganic salt.
SUMMERY OF THE UTILITY MODEL
The utility model aims to overcome the defects of the prior art and provide a device for purifying silver nitrate by layer type integral crystallization.
The purpose of the utility model is accomplished through following technical scheme. A device for purifying silver nitrate by layer type integral crystallization comprises a heat exchange crystallizer, wherein a feeding pipeline, a pure water feeding pipeline and a circulating pipeline are connected with an inlet of the heat exchange crystallizer; the heat exchange crystallizer consists of a tube pass and a shell pass, and a distributor is arranged in the heat exchange crystallizer; the shell pass of the heat exchange crystallizer is connected with a heat exchange medium inlet pipeline and a heat exchange medium outlet pipeline; a discharge pipeline of the heat exchange crystallizer is communicated with an inlet of a high-purity silver nitrate storage tank or a mother liquor storage tank through valve switching; the outlet of the high-purity silver nitrate storage tank is connected with a product pump and a product discharge pipeline; the outlet of the mother liquor storage tank is connected with a material circulating pump, and the material circulating pump is switched by a valve to be communicated with a circulating pipeline or a mother liquor pipeline.
Preferably, the heat exchange crystallizer is a shell and tube heat exchanger, a falling film crystallizer, a plate-fin heat exchanger or a plate heat exchanger.
Preferably, the heat exchange medium inlet pipeline and the heat exchange medium outlet pipeline are connected with the freezing and temperature-rising control device.
The mechanism of the utility model is as follows: the solubility of silver nitrate in water increases greatly with temperature, and the solubility of silver nitrate at different temperatures is shown in the table below, and the solubility at 100 ℃ is about 7 times that at 0 ℃.
| Temperature of | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 80 | 100 |
| Silver nitrate ficus microcarpa degree of decomposition g | 122 | 167 | 212 | 265 | 311 | 440 | 585 | 652 | 733 |
The utility model discloses utilize the silver nitrate characteristic of high solubility under the temperature rise, creatively with the mother liquor that hides in the silver nitrate crystal and between the crystal dissolve behind a small amount of crystals of cladding under the intensification condition through clearance discharge, reach the perspire process of similar melting crystallization technology, improve purity. Moreover, the method and the device for purifying silver nitrate by using layered integral crystallization are successfully developed by changing the system structure of the device, applying the method to the purification process of silver nitrate solution and dissolving silver nitrate crystal by using pure water to prepare high-purity silver nitrate solution.
The utility model has the advantages that:
1. compare traditional kettle-type crystallizer, the utility model discloses heat transfer area is big, and crystallization efficiency is high, and the high-purity silver nitrate purity of preparation can reach the photographic grade.
2. The product has high purity. The method has the advantages that residual liquid is discharged through draining, heating and cleaning, the mother liquid residual liquid is reduced, the product purity is improved, and particularly in the process of heating and discharging the residual liquid, the mother liquid occluded in silver nitrate crystals and among the crystals is creatively discharged through gaps after a small amount of crystals coated in the mother liquid are dissolved under the heating condition by utilizing the high solubility of the silver nitrate after the temperature is raised.
Drawings
FIG. 1 is a schematic view of an apparatus for purifying silver nitrate by bulk crystallization in a layered form;
the symbols in the figure show that (1) a feeding pipeline, (2) a pure water feeding pipeline, (3) a distributor, (4) a heat exchange crystallizer, (5) a discharging pipeline, (6) a high-purity silver nitrate storage tank and (7) a mother liquor storage tank; (8) the system comprises a material circulating pump, a product pump (9), a circulating pipeline (10), a mother liquor pipeline (11), a product discharging pipeline (12), a heat exchange medium inlet pipeline (13) and a heat exchange medium outlet pipeline (14).
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings and embodiments:
the utility model discloses a method for purifying silver nitrate by layer type integral crystallization, which comprises the following steps:
s1, liquid-phase feeding: adding a material silver nitrate solution into a heat exchange crystallizer 4 through a feeding pipeline 1; enters the heat exchange surface of the crystallizer through a distributor 3 in the heat exchange crystallizer 4; the material enters a mother liquid storage tank 7 through a discharge pipeline 5, and a material circulating pump 8 circulates the material through a circulating pipeline 10; the silver nitrate solution is prepared by dissolving metal silver by nitric acid, contains 40-95 wt% of silver nitrate and has a feeding temperature of 50-120 ℃.
S2, cooling and crystallizing: starting cooling circulation in the shell pass of the heat exchange crystallizer 4, circulating a cooling medium through a heat exchange medium inlet pipeline 13 and a heat exchange medium outlet pipeline 14, and crystallizing a silver nitrate solution in the tube pass of the heat exchange crystallizer 4 on the tube wall in an upper layer manner; wherein the cooling medium is glycol solution, salt water, heat conducting oil or water; the cooling rate is 0.1-30 ℃/min, and the final crystallization temperature is 0-20 ℃.
S3, draining: after crystallization is finished, stopping the material circulating pump 8, standing for 1-3 hours, draining the mother liquor adsorbed on the surface of the crystal in the tube pass of the heat exchange crystallizer 4, and allowing the mother liquor to enter a mother liquor storage tank 7;
s4, heating to discharge residual liquid: starting heating circulation in the shell pass of the heat exchange crystallizer 4, circulating a heating medium through a heat exchange medium inlet pipeline 13 and a heat exchange medium outlet pipeline 14, wherein the heating rate is 0.1-30 ℃/min, and the final temperature is 55-95 ℃; mother liquor occluded in silver nitrate crystals and among crystals on the tube side wall surface of the heat exchange crystallizer 4 is dissolved and coated with a small amount of crystals under the condition of temperature rise and then flows into a mother liquor storage tank 7 through gaps;
s5, cleaning: a small amount of high-purity saturated silver nitrate solution is fed into a feed pipeline 1 or a small amount of pure water is fed into a pure water feed pipeline 2 to clean silver nitrate crystals, and the silver nitrate crystals flow into a mother liquor storage tank 7;
s6, dissolving and discharging: pure water dissolves silver nitrate crystals through a pure water feeding pipeline 2, the prepared high-purity silver nitrate solution flows into a high-purity silver nitrate storage tank 6, and a product pump 9 enters the next working procedure through a product discharging pipeline 12; the material circulating pump 8 recycles the mother liquor in the mother liquor storage tank 7 after passing through the next purification process through a mother liquor pipeline 11. The high-purity silver nitrate solution is crystallized twice or more by repeating the steps S1-S6, so that the purity is further improved; the purity of the prepared high-purity silver nitrate solution is higher than 99.8%, and the high-purity silver nitrate solution is crystallized and dried to prepare a solid finished product.
As shown in fig. 1, the utility model provides a device for purifying silver nitrate by layered integral crystallization, which comprises a heat exchange crystallizer 4, wherein a feed pipeline 1, a pure water feed pipeline 2 and a circulating pipeline 10 are connected with the inlet of the heat exchange crystallizer 4; the heat exchange crystallizer 4 consists of a tube pass and a shell pass, and a distributor 3 is arranged in the heat exchange crystallizer; the heat exchange crystallizer 4 is a shell and tube heat exchanger, a falling film crystallizer, a plate-fin heat exchanger or a plate heat exchanger. The shell pass of the heat exchange crystallizer 4 is connected with a heat exchange medium inlet pipeline 13 and a heat exchange medium outlet pipeline 14, and the heat exchange medium inlet pipeline 13 and the heat exchange medium outlet pipeline 14 are connected with a freezing temperature rise control device. A discharge pipeline 5 of the heat exchange crystallizer 4 is switched to enter a high-purity silver nitrate storage tank 6 or a mother liquor storage tank 7 through a valve; the outlet of the high-purity silver nitrate storage tank 6 is connected with a product pump 9 and a product discharge pipeline 12; an outlet of the mother liquor storage tank 7 is connected with a material circulating pump 8, and the material circulating pump 8 is switched to enter a circulating pipeline 10 or a mother liquor pipeline 11 through a valve.
Preparing a silver nitrate solution raw material, wherein the raw material is obtained by reacting national standard No. 2 silver ingot with analytically pure 63% nitric acid, and obtaining a 87% wt silver nitrate solution after vacuum evaporation at the temperature of 98 ℃.
The detection method of the chemical reagent silver nitrate GB/T670-.
Example 1
Using the apparatus shown in fig. 1, first, liquid phase feed: a raw material solution of 830kg of silver nitrate was fed through a feed line 1 into a falling-film crystallizer (heat exchange crystallizer 4) of 1.2m 3; the distributor 3 of the falling film melting crystallizer is utilized to distribute films on the inner side of the crystallizer tube; the material enters a mother liquid storage tank 7 with the length of 1m3 through a discharge pipeline 5; the material circulating pump 8 circulates materials through a circulating pipeline 10;
then, cooling and crystallizing: starting cooling circulation in the shell pass of the heat exchange crystallizer 4, cooling the glycol solution at a cooling rate of 0.5 ℃/min from 95 ℃ to 0 ℃, keeping the temperature of 0 ℃ for 1 hour, and controlling the temperature of the glycol solution by a program temperature controller. And stopping the material circulating pump 8, standing for 1 hour, and draining the mother liquor adsorbed on the crystal surface in the tube pass of the heat exchange crystallizer 4 into a mother liquor storage tank 7. Then heating to discharge residual liquid: starting heating circulation in the shell pass of the heat exchange crystallizer 4, wherein the heating rate is 2 ℃/min, and mother liquor occluded in silver nitrate crystals and among crystals on the wall surface of the tube pass of the heat exchange crystallizer 4 dissolves a small amount of coated crystals under the heating condition and then flows into a mother liquor storage tank 7 through gaps; next, cleaning: 5L of pure water washes the silver nitrate crystals through feed line 2 and flows into mother liquor storage tank 7.
Finally, material dissolving and discharging: 200L of 50 ℃ pure water dissolves silver nitrate crystals through the pure water feed line 2, and flows into the high-purity silver nitrate storage tank 6 to prepare 695kg of 68 wt% silver nitrate solution. And (4) carrying out purity detection on the prepared high-purity silver nitrate.
Comparative example 1
A common 1m3 jacket groove type crystallizer is used, the temperature of the glycol solution is reduced at the rate of 0.5 ℃/min, the temperature is reduced from 95 ℃ to 0 ℃, the temperature is kept constant for 1 hour at 0 ℃, then the material crystal is centrifuged, and the oven is hollow and dried, and finally the purity is measured, the result is shown in the table I, and the comparison between the example 1 and the comparative example 1 shows that the purity of the silver nitrate using the method in the aspect is greatly improved.
Comparative example 2
Referring to example 1, the temperature-rising raffinate discharged in step S4 is eliminated, the purity results are shown in the table I under the same process conditions, and the comparison between example 1 and comparative examples 1 and 2 shows that the temperature-rising raffinate discharging process has a great influence on the purity of silver nitrate, but has a higher purity than that of comparative example 1.
Example 2
The purity result of the product obtained by re-crystallizing the high-purity silver nitrate prepared in the embodiment 1 by using the method and the device is shown in the table I, and the comparison between the embodiment 2 and the embodiment 1 shows that the purity of the silver nitrate is further improved, and the secondary level of the silver nitrate for photographing with higher purity can be reached by referring to the standard detection of the silver nitrate for photographing in YS/T476-2005.
Example 3
Using a shell and tube heat exchange crystallizer, the rest of which is the same as the device used in the example 1, using 500kg of silver nitrate raw material solution as a raw material, cooling and crystallizing: starting cooling circulation in the shell pass of the heat exchange crystallizer 4, cooling the sodium chloride brine at the cooling rate of 4 ℃/min, cooling the temperature from 80 ℃ to 10 ℃, and keeping the temperature at 10 ℃ for 1 hour. And stopping the material circulating pump 8, standing for 2 hours, and draining residual liquid on the surface of the crystal. Then heating to discharge residual liquid: starting heating circulation in the shell pass of the heat exchange crystallizer 4, wherein the heating rate is 10 ℃/min, and mother liquor occluded in silver nitrate crystals and among crystals on the wall surface of the tube pass of the layered crystallizer dissolves a small amount of coated crystals under the heating condition and then flows into a mother liquor storage tank 7 through gaps; next, cleaning: 3L of high-purity silver nitrate saturated solution is used for cleaning silver nitrate crystals through a feed line 2 and flows into a mother liquor storage tank 7.
Finally, material dissolving and discharging: 80L of pure water at 25 ℃ dissolves silver nitrate crystals through the pure water feed line 2, and flows into the high-purity silver nitrate storage tank 6 to prepare 206kg of 61 wt% silver nitrate solution. And (4) carrying out purity detection on the prepared high-purity silver nitrate.
TABLE-silver nitrate purity test results
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (3)
1. The utility model provides a device of layer type bulk crystallization purification silver nitrate which characterized by: the device comprises a heat exchange crystallizer (4), wherein a feeding pipeline (1), a pure water feeding pipeline (2) and a circulating pipeline (10) are jointly connected with an inlet of the heat exchange crystallizer (4); the heat exchange crystallizer (4) consists of a tube pass and a shell pass, and a distributor (3) is arranged in the heat exchange crystallizer; the shell pass of the heat exchange crystallizer (4) is connected with a heat exchange medium inlet pipeline (13) and a heat exchange medium outlet pipeline (14); a discharge pipeline (5) of the heat exchange crystallizer (4) is communicated with an inlet of a high-purity silver nitrate storage tank (6) or a mother liquor storage tank (7) through valve switching, and an outlet of the high-purity silver nitrate storage tank (6) is connected with a product pump (9) and a product discharge pipeline (12); the outlet of the mother liquor storage tank (7) is connected with a material circulating pump (8), and the material circulating pump (8) is switched by a valve to be communicated with a circulating pipeline (10) or a mother liquor pipeline (11).
2. The device for purifying silver nitrate by layer bulk crystallization according to claim 1, wherein: the heat exchange crystallizer (4) is a shell and tube heat exchanger, a falling film crystallizer, a plate-fin heat exchanger or a plate heat exchanger.
3. The layered bulk crystallization silver nitrate purifying apparatus according to claim 1, wherein: the heat exchange medium inlet pipeline (13) and the heat exchange medium outlet pipeline (14) are connected with the freezing and temperature rising control device.
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| CN202221199381.7U CN217367229U (en) | 2022-05-18 | 2022-05-18 | Device of layer type integral crystallization purification silver nitrate |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114797157A (en) * | 2022-05-18 | 2022-07-29 | 浙江海钛新材料科技股份有限公司 | Method and device for purifying silver nitrate by layer type integral crystallization |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114797157A (en) * | 2022-05-18 | 2022-07-29 | 浙江海钛新材料科技股份有限公司 | Method and device for purifying silver nitrate by layer type integral crystallization |
| CN114797157B (en) * | 2022-05-18 | 2024-05-17 | 浙江海钛新材料科技股份有限公司 | Method and device for purifying silver nitrate by layered integral crystallization |
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