CN217409771U - Device for continuously preparing high-purity large-particle silver nitrate crystals - Google Patents
Device for continuously preparing high-purity large-particle silver nitrate crystals Download PDFInfo
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- CN217409771U CN217409771U CN202221353119.3U CN202221353119U CN217409771U CN 217409771 U CN217409771 U CN 217409771U CN 202221353119 U CN202221353119 U CN 202221353119U CN 217409771 U CN217409771 U CN 217409771U
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Abstract
The invention discloses a device for continuously preparing high-purity large-particle silver nitrate crystals. The device comprises a flash evaporation chamber, a crystallization chamber, a central cylinder, a heat exchange device, a circulating pump, a separation cleaning device, a drying device and a connecting pipeline. The method is easy to prepare large-grain high-purity silver nitrate crystals, the product crystals are uniform in grain and efficient in crystallization, and continuous production is realized.
Description
Technical Field
The utility model relates to a crystallization device field mainly is a device of serialization preparation high purity large granule silver nitrate crystal.
Background
Silver nitrate is a colorless crystal, readily soluble in water, commonly used in photographic emulsions, silver plating, mirror making, printing, medicine, hair dyeing, and testing for chloride, bromide, and iodide ions, and is also used in the electronics industry. In the industrial evaporative crystallization process, water in the silver nitrate solution is usually evaporated by heating or reducing pressure, and when the solution is concentrated to the surface of a crystallization film, the solution is sent to a crystallization kettle for cooling crystallization.
The conventional silver nitrate crystallization industry often adopts an intermittent device to obtain large-crystal silver nitrate in a crystallization kettle, but the crystals are easy to be connected into crystal clusters, mother liquor is carried, and the product purity is influenced.
Patent publication No. CN111732120A discloses an environment-friendly and efficient production method of high-purity silver nitrate, which comprises the steps of firstly obtaining 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.
Patent publication No. CN215352080U a silver nitrate crystallization device, provides a neotype crystallization device, through connecting a plurality of scrapers in the cauldron, has increased the mobility of solution in the cauldron, reduces the adhesiveness of silver nitrate crystal at cauldron internal wall, and consequently improves the yield, but its production flow still does not intermittent type formula, only reacts in single crystallization kettle, when the output increases, still can appear the solute deposit on heat transfer surface, reduces crystallization efficiency.
Patent publication No. CN215612076U silver nitrate pipeline breaker discloses a silver nitrate pipeline breaker, utilizes telling rotatory broken reamer to cut the breakage to the silver nitrate crystal block, and the silver nitrate crystal size after the breakage is even, is favorable to the surperficial edulcoration. However, the method does not fundamentally solve the problem that crystal crystals are easy to form crystal clusters caused by the conventional crystallization reaction device, but only carries out secondary treatment on products by physical means, and the energy consumption problem caused by large-scale production also limits the application of the method.
SUMMERY OF THE UTILITY MODEL
The utility model aims to overcome the defects of the prior art and provide a device for continuously preparing high-purity large-particle silver nitrate crystals.
The purpose of the utility model is achieved by the following technical scheme. A device for continuously preparing high-purity large-particle silver nitrate crystals comprises a flash evaporation chamber, a crystallization chamber, a central cylinder, a heat exchange device, a circulating pump, a separation cleaning device and a drying device, wherein a feed inlet is communicated with the input end of the heat exchange device, and the output end of the heat exchange device is communicated with the input end of the flash evaporation chamber; a central cylinder is arranged at the central position of the crystallization chamber, a crystal fluidized bed is formed in the crystallization chamber, and the bottom output end of the flash evaporation chamber is communicated with the central cylinder; the upper part of the crystallization chamber is provided with an overflow weir, the side wall of the upper part of the crystallization chamber is provided with a mother liquor outlet, the inner cavity of the crystallization chamber is communicated with the mother liquor outlet through the overflow weir, the mother liquor outlet is communicated with the input end of the heat exchange device through a circulating pump, and the discharge hole at the bottom of the crystallization chamber is sequentially communicated with the separation cleaning device and the drying device.
Furthermore, the heat exchange device comprises a condensate water circulating heat exchange part and a steam circulating heat exchange part, the condensate water circulating heat exchange part comprises a condensate water inlet and a condensate water outlet, the steam circulating heat exchange part comprises a steam inlet and a steam outlet, and the steam inlet is communicated with the steam outlet through a steam pipe.
Furthermore, the central cylinder is of a hollow cylinder structure, one end of the central cylinder is communicated with the bottom output end of the flash evaporation chamber, and the other end of the central cylinder extends to the position, close to the bottom, of the crystallization chamber.
Furthermore, a reflux drain port is arranged on the side wall of the bottom of the crystallization chamber, and a jacket A is arranged on the inner wall of the crystallization chamber and is communicated with a steam pipe in the heat exchange device.
Furthermore, a jacket B is arranged on the wall of the central cylinder body and is communicated with a steam pipe in the heat exchange device.
Furthermore, the filtrate obtained by the separation and cleaning device is communicated with the mother liquor outlet through a pipeline.
The utility model has the advantages that:
1. the production process realizes the continuity, the materials in the crystallization device are recycled, and the production efficiency is further improved;
2. the obtained silver nitrate crystal is separated out on a crystal fluidized bed, the product particles are large, the crystal grows in a closed high-purity silver nitrate solution environment, and circulating mother liquor is continuously used for washing fine particles, so that the product crystal has high purity. By adopting a jacket heating structure and controlling the temperature and the pressure in the central cylinder, the maximum growth of crystals of silver nitrate mother liquor on a crystal fluidized bed in a crystallization chamber can be in a millimeter level under stable experimental conditions;
3. through the design of overflow weir, let tiny granule along with the mother liquor outflow crystallization room, the growth process of large granule is more even unanimous, helps obtaining the crystal body that the homogeneity is good at crystallization room bottom discharge gate, also avoids a large amount of tiny particle solutes to deposit the adhesion phenomenon in the crystallization room simultaneously.
4. And a secondary heat exchange device is adopted, a condensate water circulating heat exchange part is adopted for cooling the mother liquor which enters the circulation again, and then heat exchange regulation is carried out through a steam circulating heat exchange part, so that the preheating effect of the silver nitrate solution is ensured.
Drawings
Fig. 1 is a schematic structural diagram of the device of the present invention.
Description of reference numerals: the device comprises a feed inlet 1, a heat exchange device 2, a flash evaporation chamber 3, a central cylinder 4, a crystallization chamber 5, a crystal fluidized bed 6, an overflow weir 7, a discharge port 8, a separation cleaning device 9, a drying device 10, a circulating pump 11, a steam inlet 12, a steam outlet 13, a condensed water inlet 14, a condensed water outlet 15, a steam port 16, a reflux drain port 17, a jacket A18, a jacket B19 and a mother liquid outlet 20.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings and embodiments:
the utility model discloses a device for continuously preparing high-purity large-particle silver nitrate crystals, which comprises a flash evaporation chamber 3, a crystallization chamber 5, a central cylinder 4, a heat exchange device 2, a circulating pump 11, a separation cleaning device 9 and a drying device 10, wherein a feed inlet 1 is communicated with the input end of the heat exchange device 2, and the output end of the heat exchange device 2 is communicated with the input end of the flash evaporation chamber 3; the central position of crystallization chamber 5 is equipped with central barrel 4, and central barrel 4 is hollow tube structure, forms crystal fluidized bed 6 in the crystallization chamber, and the one end of central barrel 4 is linked together with the bottom output of flash chamber 3, and the other end of central barrel 4 extends to the position that crystallization chamber 5 is close to the bottom. An overflow weir 7 is arranged at the upper part of the crystallization chamber 5, a mother liquor outlet 20 is arranged on the side wall of the upper part of the crystallization chamber 5, the inner cavity of the crystallization chamber 5 is communicated with the mother liquor outlet 20 through the overflow weir 7, the mother liquor outlet 20 is communicated with the input end of the heat exchange device 2 through a circulating pump 11, a discharge port 8 at the bottom of the crystallization chamber 5 is sequentially communicated with a separation cleaning device 9 and a drying device 10, and the drying device 10 is preferably a microwave dryer.
The heat exchange device 2 comprises a condensate water circulating heat exchange part and a steam circulating heat exchange part, and performs heat exchange through a tube pass, the condensate water circulating heat exchange part comprises a condensate water inlet 14 and a condensate water outlet 15, the steam circulating heat exchange part comprises a steam inlet 12 and a steam outlet 13, and the steam inlet 12 is communicated with the steam outlet 13 through a steam tube. The condensed water circulating heat exchange part is used for cooling the mother liquid which enters the circulation again, and then the heat exchange regulation is carried out through the steam circulating heat exchange part, so that the preheating effect of the silver nitrate solution is ensured.
The side wall of the bottom of the crystallization chamber is provided with a backflow drain port 17 for discharging the residual materials after the crystallization chamber is used for a period of time; the inner wall of the crystallization chamber is provided with a jacket A18 and is communicated with a steam pipe in the heat exchange device, and the cylinder wall of the central cylinder is provided with a jacket B19 and is communicated with the steam pipe in the heat exchange device. The jacket A18 and the jacket B19 fully utilize steam in the heat exchange device, and the jacket wraps and heats the steam to ensure that the crystallization chamber and the central cylinder body crystallize at a certain temperature.
The mechanism of the utility model is as follows: the utility model discloses the feed liquid (silver nitrate solution) with continuous production adds in the circulating pipe, mix with intraductal circulation mother liquor, silver nitrate solution is passed through the pump sending by feed inlet 1 to heat transfer device 2, get into flash distillation chamber 3 after rising temperature in heat transfer device 2, solution after the heating evaporates and reaches the supersaturation (the silver nitrate solution that makes to get hot through the negative pressure effect forms supersaturation silver nitrate steam) in flash distillation chamber (evaporation chamber), the supersaturation silver nitrate solution of formation gets into crystal fluidized bed 6 in crystallization chamber 5 below flash distillation chamber 3 through central barrel 4, and appear on crystal fluidized bed 6. In the crystal fluidized bed 6, a solute supersaturated in the solution is deposited on the surface of the suspended particles, causing the crystals to grow. The crystal fluidized bed carries out hydraulic classification on the particles, large particles are below, small particles are above, and the crystallized product with uniform particle size is discharged from the bottom of the fluidized bed. The fine particles in the fluidized bed flow into the circulating pipe along with the mother liquor through the overflow weir 7 and the mother liquor outlet 20 to return to the circulation again, and when the circulation pipe is heated again, the fine crystals in the fine particles are dissolved.
The mother liquor is purified periodically, crystals precipitated at the bottom of the crystallization chamber enter a separation cleaning device 9 from a discharge port 8, the crystals are dried after being cleaned and finally packaged into a product, and filtrate obtained by the separation cleaning device is communicated with a mother liquor outlet through a pipeline, so that the filtrate is recycled. Through set up backward flow drain-off mouth in central barrel below, be equipped with the overflow weir at crystallization chamber lateral part mother liquor export for the mother liquor washes crystal outflow bed, takes out the crystallization chamber with tiny crystal, gets into circulating device again and participates in the reaction, has effectively avoided solute deposition phenomenon.
The utility model discloses a method for continuously preparing high-purity large-particle silver nitrate crystals, which comprises the following steps:
the silver nitrate solution of the S1 liquid phase enters the heat exchange device from the feed inlet, and the temperature of a heating calandria in the heat exchange device is heated within the range of 65-110 ℃; wherein the raw material of the silver nitrate solution is a silver nitrate solution prepared by dissolving metal silver by nitric acid, the silver nitrate solution contains 40-95 wt% of silver nitrate, and the temperature of the solution is 30-85 ℃.
S2, the preheated silver nitrate solution enters a flash evaporation chamber through a pipeline, steam flows out from the upper part under the negative pressure state in the flash evaporation chamber, the supersaturated solution enters a crystallization chamber from the lower part through a central cylinder, and crystals are slowly separated out on a crystal fluidized bed in the crystallization chamber;
s3, in a crystallization chamber with constant temperature and constant pressure, a supersaturated solution separates out crystals, large-particle crystals are uniformly gathered at the bottom due to a hydraulic classification effect, fine particles are wrapped by mother liquor and flow out of the crystallization chamber from an overflow weir, and the mother liquor is periodically purified and enters circulation again; wherein the flow rate of the mother liquor flowing out of the crystallization chamber through the overflow weir is 0.5-2.5 m/s.
S4 large-particle crystals enter a centrifugal cleaning device from a discharge hole at the bottom, small-particle crystals are removed through centrifugal separation, then the surface is washed by high-purity saturated silver nitrate solution or electronic-grade pure water, and cleaning fluid and filtrate are recycled; wherein, the purity of the high-purity saturated silver nitrate solution is higher than 99.8 percent;
s5, drying the crystals within the standard particle size range in a drying device, and finally entering a packaging workshop, wherein the crystals are high-purity large-particle silver nitrate crystal products after detection and packaging; the grain diameter of the prepared silver nitrate crystal is 100 mu m-10 mm, and the purity is higher than 99.8%.
The silver nitrate purity in the preparation process is detected by using a detection method in GB/T670-2007 chemical reagent silver nitrate, and the detection result is shown in the table I.
Example 1
The device shown in figure 1 is used, firstly, raw material solution of 900kg of silver nitrate enters a heat exchange device from a feeding hole, after the temperature in the heat exchange device is raised to 95 ℃, the raw material solution enters a flash evaporation chamber, steam flows out from the top under the condition of negative pressure, supersaturated silver nitrate solution enters a crystallization chamber from a central cylinder, the heating temperature of the central cylinder and the jacket of the crystallization chamber is 80 ℃, crystals are separated out on a crystal fluidized bed, mother liquor flows out of the crystallization chamber through a flushing fluidized bed at the flow velocity of 1.3m/s through an overflow weir, and then enters the heat exchange device again for circulation.
After reacting for two hours, leading out the crystals from a discharge port, putting the crystals into a separation and cleaning device, carrying out centrifugal separation at the rotating speed of 3000rpm to obtain solids, washing the crystals by 10L of saturated silver nitrate solution with the purity of 99.8 percent and the temperature of 50 ℃, leading out the washed solids into a microwave dryer, and carrying out vacuum drying for 20min to obtain 475kg of silver nitrate crystals with the average particle size of 2.45 mm. And (4) carrying out purity detection on the prepared high-purity large-particle silver nitrate crystal.
Comparative example 1
The silver nitrate crystal is prepared by a conventional cooling crystallization method, and the method for preparing the silver nitrate crystal refers to an example in a patent publication No. CN1386707A, and the specific implementation method is as follows.
Introducing 900kg of silver nitrate solution into a solution reaction kettle, heating the silver nitrate solution to 50 ℃ when the concentration of the silver nitrate is 52%, adding 180L of 68% nitric acid, fully stirring and uniformly mixing, wherein the concentration of the nitric acid in the solution is 15%. The temperature in the autoclave was maintained at 60 ℃ and air was introduced for 1 hour. The solution was cooled to 0 ℃ and dried by centrifugation to give 434kg of silver nitrate crystals having an average particle size of 6.8. mu.m.
The comparison between the example 1 and the comparative example 1 shows that the continuous production of the silver nitrate crystal prepared by the conventional method cannot be realized, the material is supplemented to the solution in the device from time to time, the solute attachment phenomenon is easy to occur on the inner wall of the kettle and the pipeline due to cooling crystallization, the final yield is influenced, the particle size and the purity of the product are compared, and the product obtained in the example 1 has large particle size and high purity, so that the continuous production can be realized.
Example 2
The feeding temperature before the flash chamber in the step of example 1 is adjusted to 105 ℃, the outflow rate of the mother liquor in the crystallization chamber is reduced to 0.7m/s, the reaction is carried out for 45min, and 416kg of silver nitrate crystals with the average grain diameter of 676 micrometers are finally prepared.
Example 3
The feeding temperature before the flash chamber in the step of example 1 is increased to 105 ℃, the jacket heating temperature of the crystallization chamber and the central cylinder is adjusted to 75 ℃, the outflow flow rate of the mother liquor is increased to 2.2m/s, and the constant temperature and pressure reaction is carried out for 4 hours, so 497kg of silver nitrate crystals with the average grain diameter of 6.88mm is finally prepared.
TABLE-silver nitrate purity test results
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by 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 (6)
1. The utility model provides a device of serialization preparation high purity large granule silver nitrate crystal which characterized in that: the device comprises a flash evaporation chamber, a crystallization chamber, a central cylinder, a heat exchange device, a circulating pump, a separation cleaning device and a drying device, wherein a feed inlet is communicated with the input end of the heat exchange device, and the output end of the heat exchange device is communicated with the input end of the flash evaporation chamber; a central cylinder is arranged at the central position of the crystallization chamber, a crystal fluidized bed is formed in the crystallization chamber, and the bottom output end of the flash evaporation chamber is communicated with the central cylinder; the upper part of the crystallization chamber is provided with an overflow weir, the side wall of the upper part of the crystallization chamber is provided with a mother liquor outlet, the inner cavity of the crystallization chamber is communicated with the mother liquor outlet through the overflow weir, the mother liquor outlet is communicated with the input end of the heat exchange device through a circulating pump, and the discharge hole at the bottom of the crystallization chamber is sequentially communicated with the separation cleaning device and the drying device.
2. The apparatus for continuously preparing high-purity large-particle silver nitrate crystals according to claim 1, wherein: the heat exchange device comprises a condensate water circulating heat exchange part and a steam circulating heat exchange part, the condensate water circulating heat exchange part comprises a condensate water inlet and a condensate water outlet, the steam circulating heat exchange part comprises a steam inlet and a steam outlet, and the steam inlet is communicated with the steam outlet through a steam pipe.
3. The apparatus for continuously preparing high-purity large-particle silver nitrate crystals according to claim 1, wherein: the central cylinder is of a hollow cylinder structure, one end of the central cylinder is communicated with the bottom output end of the flash chamber, and the other end of the central cylinder extends to the position, close to the bottom, of the crystallization chamber.
4. The apparatus for continuously preparing high-purity large-particle silver nitrate crystals according to claim 1, wherein: the side wall of the bottom of the crystallization chamber is provided with a backflow drain hole, and the inner wall of the crystallization chamber is provided with a jacket A and communicated with a steam pipe in the heat exchange device.
5. The apparatus for continuously preparing high-purity large-particle silver nitrate crystals according to claim 1 or 3, wherein: the wall of the central cylinder is provided with a jacket B and communicated with a steam pipe in the heat exchange device.
6. The apparatus for continuously preparing high-purity large-particle silver nitrate crystals according to claim 1, wherein: and the filtrate obtained by the separation and cleaning device is communicated with the mother liquor outlet through a pipeline.
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