Preparation method of nanoscale high-purity activated zinc oxide

Abstract

The invention belongs to the technical field of chemical product preparation, and particularly relates to a nanoscale high-purity activated zinc oxide preparation method which comprises the following steps: a, screening: putting zinc-containing powder into a powder screening barrel of a screening mechanism for screening, and feeding the screened powder into a mixing and stirring tank; according to the preparation method of the nanoscale high-purity activated zinc oxide, basic zinc carbonate contained in the zinc oxide prepared in the steps a, b, c, d and e is set as an activated zinc oxide carrier, so that the reaction interface of the nano zinc oxide is improved, and when the pH value of a leaching solution in the process of adding during stable mixing and stirring exists or the stirring reaction temperature of a reaction tank is relatively high, the reaction temperature of the reaction tank is relatively high; the quality of improving the content of the zinc oxide is realized when the zinc oxide is used as a raw material or sodium carbonate with higher concentration is used for preparation operation or the drying temperature of a leaching filter cake is higher, and the zinc oxide has a larger specific surface area.

Description

Technical Field

[0001] The invention relates to the technical field of chemical product preparation, and in particular to a method for preparing nanometer-level high-purity active zinc oxide. Background Art

[0002] Nano zinc oxide (ZnO) is a new type of high-functional fine inorganic product with a particle size between 1-100nm, facing the 21st century. It exhibits many special properties, such as non-migration, fluorescence, piezoelectricity, absorption and scattering of ultraviolet rays, etc. High-purity zinc oxide is an indispensable high-tech raw material in modern industry and has a wide range of uses. It is mainly used in dozens of industries and enterprises such as glass, feed, ceramics, dyes, paints, papermaking, rubber, pesticides, oil refining, galvanizing, special steel, alloys, national defense science and technology, etc. There is a huge demand for it and the purity requirements are very high.

[0003] Among the several production processes of zinc oxide, the direct method is the most likely to contain iron impurities, which are mainly brought in during the production process. The existing preparation method of nano zinc oxide directly precipitates in the reaction tank, and the agglomeration phenomenon between particles is serious. After calcination, the product particle size distribution is wide, easy to agglomerate, and the specific surface area is reduced. At present, the specific surface area of ​​active nano zinc oxide products on the market is basically 40-65m2 / g, and there are few active zinc oxides that exceed 65m2 / g, so a method for preparing nano-level high-purity active zinc oxide is needed. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, improve the preparation method of wet zinc oxide leachate, further reduce the iron impurities in the product, make the obtained zinc oxide highly active and suitable for continuous industrial production, the present invention proposes a method for preparing nano-scale high-purity active zinc oxide, comprising the following steps:

[0005] a. Screening: Put the zinc-containing powder into the powder screening barrel of the screening mechanism for screening. After screening, the powder is sent to the mixing tank.

[0006] b. Mixing and stirring: Add the leaching liquid into the mixing and stirring tank at the same time. The leaching liquid contains NH 3 and (NH 4 )2SO 4 The mixture with a pH value of 5.0 to 5.5 is mixed with the sieved powder and stirred at room temperature by a mixing barrel stirring mechanism at a stirring speed of 75 to 85 r / min.

[0007] c. Reaction stirring: After the mixed liquid in the mixing and stirring tank enters the reaction stirring device through the overflow port of the mixing and stirring tank, it is heated by the reaction stirring device and stirred for reaction. The Fe2+ in the zinc sulfate plating solution is oxidized into Fe3+ with a strong oxidant. The leachate is obtained by sampling and calibration when the zinc content is 115-125g / L, and the soda solution is added to synthesize and generate a precipitate.

[0008] d. Precipitation and drying: The precipitate is filtered, and after the filter cake is dried, the classification particle size is controlled to 200 meshes, and after drying again, it is screened through a vibrating screen with a mesh number of 325 meshes.

[0009] e. Calcination and grinding: The dried and screened product is returned to the brick kiln for calcination for 1 hour via adjustable electricity to produce highly active zinc oxide.

[0010] Preferably, the leaching liquid in the mixed stirring is an ammonia complex containing sulfate, the process pH value is 4.5-5.2, the temperature in the reaction stirring is maintained at 45-55°C for filtration, the stirring speed is 55-65r / min, the stirring time is 4-6 hours, and the soda ash solution is added after stirring for 4-6 hours, and the soda ash solution uses a 15-21wt% soda ash solution.

[0011] Preferably, the soda ash solution also uses a 10-23 wt % soda ash solution.

[0012] Preferably, in the precipitation drying, the filter cake drying temperature of the precipitation filter pressing is set to 300-350°C.

[0013] In the precipitation drying, the filter cake drying temperature of the precipitation filter pressing is also set to 350-400°C, and the calcination temperature is 600-700°C.

[0014] Preferably, the reaction stirring device comprises a fixed base, a PLC controller and a stirring reaction tank are fixedly mounted on the upper surface of the fixed base, a treatment tank is provided on the surface of the stirring reaction tank, a sealing door whose surface is plugged into the surface of the stirring reaction tank is hingedly mounted on the inner wall of the treatment tank, and an overflow liquid inlet pipe is fixedly connected to the surface of the stirring reaction tank.

[0015] An electric heater is fixedly installed on the surface of the stirred reaction tank, and the electric heater is electrically connected to the PLC controller through a cable, and the electric heater includes a spiral heating tube.

[0016] The inner wall of the stirred reaction tank is fixedly connected with a heat-insulating layer, the surface of the heat-insulating layer is provided with an avoidance groove adapted to the spiral heating tube, the surface of the heat-insulating layer and the inner wall of the avoidance groove are both fixedly connected with a reflective film, the surface of the reflective film is provided with a heat-conducting layer, and the heat-conducting layer is fixedly connected to the inner wall of the stirred reaction tank by screws.

[0017] The spiral heating tube is arranged in the avoidance groove and between the reflective film and the heat-conducting layer.

[0018] The interior of the thermal insulation layer is aerogel felt, and the interior of the heat conductive layer is a metal heat conductive sheet.

[0019] Preferably, a sealing disk is fixedly connected to the upper surface of the stirring reaction tank by bolts, a stirring reduction motor is fixedly installed on the upper surface of the sealing disk, and the stirring reduction motor is electrically connected to the PLC controller through a cable.

[0020] The inner top wall of the sealing disk is rotatably connected to a stirring shaft via a bearing, and one end of the stirring shaft is fixedly connected to the reduction output end of the stirring reduction motor.

[0021] The other end of the stirring shaft extends to the interior of the stirring reaction tank, and a stirring paddle is fixedly connected to the surface of the stirring shaft. A plurality of stirring paddles are distributed in a ring array on the surface of the stirring shaft with the axis of the stirring shaft as the center.

[0022] Preferably, the inner wall of the stirred reactor is fixedly connected to a collecting hopper, the inner wall of the collecting hopper is conical, the inner bottom wall of the collecting hopper is fixedly connected to a discharge pipe, one end of the discharge pipe passes through and extends to the surface of the stirred reactor and is fixedly installed with a discharge control valve.

[0023] The surface of the discharge pipe is fixedly connected with a circulating feed pipe through a three-way pipe, and one end of the circulating feed pipe penetrates and extends to the surface of the stirring reaction tank.

[0024] A circulation pump is fixedly installed on the upper surface of the fixed base, and the circulation pump is electrically connected to the PLC controller through a cable. One end of the circulation feed pipe is fixedly connected to the inlet end of the circulation pump, and the outlet end of the circulation pump is fixedly connected to a support pipe, and a sealing locking tube is slidably sleeved on the surface of the support pipe.

[0025] Preferably, the surface of the sealing locking tube is T-shaped, the surface of the sealing locking tube is threadedly connected to the filter tube, the inner wall of the filter tube is fixedly connected with a filter net, multiple filter nets are evenly distributed on the inner wall of the filter tube, and the mesh sizes of the multiple filter nets increase from bottom to top.

[0026] A circular pipeline check valve is fixedly installed on the inner wall of the filter tube, and the circular pipeline check valve is fixedly installed below the plurality of filter screens.

[0027] One end of the filter tube is threadedly connected to a fixed sealing tube, the surface of the fixed sealing tube is T-shaped, and both ends of the filter tube are provided with rubber sealing rings whose surfaces are plugged into the surfaces of the sealing locking tube and the fixed sealing tube.

[0028] Preferably, one end of the fixed sealing tube is fixedly connected to a reflux pipe, one end of the reflux pipe penetrates and extends to the interior of the stirred reactor, the surface of the reflux pipe is fixedly connected to a monitoring tube, a temperature sensor is fixedly installed on the inner wall of the monitoring tube, and the temperature sensor is electrically connected to the PLC controller via a cable.

[0029] Preferably, the lower surface of the sealing disk is fixedly connected to the liquid storage barrel, one end of the liquid storage barrel passes through and extends to the upper surface of the sealing disk, and the surface of the liquid storage barrel is hingedly mounted with the sealing cover.

[0030] The inner bottom wall of the liquid storage barrel is fixedly connected with a liquid adding pipe, one end of which passes through and extends to the upper surface of the sealing disk, and one end of which is fixedly connected with the inner wall of the circulating feed pipe through a three-way pipe.

[0031] A solenoid valve and a flow sensor are respectively fixedly mounted on the surface of the liquid adding pipe, and both the solenoid valve and the flow sensor are electrically connected to the PLC controller via cables.

[0032] The beneficial effects of the present invention are:

[0033] 1. By setting steps a, b, c, d and e, the basic zinc carbonate contained in the prepared zinc oxide is used as an active zinc oxide carrier to improve the reaction interface of nano zinc oxide. When the pH value of the leaching solution is added during the mixing and stirring process, or the stirring reaction temperature of the reaction tank is high, or a higher concentration of soda ash is used for the preparation operation, or the drying temperature of the leached filter cake is high, the quality of the zinc oxide content is improved and the zinc oxide has a larger specific surface area.

[0034] 2. By setting up an ion exchange method to remove iron-containing impurities in wet-process zinc sulfate, the leaching process and the technical conditions controlled during the operation are improved, so that the zinc in the raw material can be completely dissolved into the solution to the greatest extent during the leaching process, and some iron impurities can be removed after the leaching displacement reaction. The output of the leached product is affected by the selection of the leaching solution, and the sedimentation rate, filtration performance, and whether it is easy to separate liquid and solid are also affected.

[0035] 3. By setting up a reaction stirring device, when in use, the mixed liquid is stirred by automatic temperature control, and during the stirring reaction process, the mixed liquid is extracted from the stirring reaction tank and filtered, and the filtered mixed liquid is refluxed into the stirring reaction tank again, so as to accelerate the flow of the mixed liquid inside the tank body and achieve better stirring reaction. Finally, the PLC controller automatically controls the soda ash solution in the liquid storage barrel to enter the stirring reaction tank to generate precipitate, thereby realizing full automatic control and achieving better effect of preparing nano zinc oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of a method for preparing nano-scale high-purity active zinc oxide proposed by the present invention;

[0037] Figure 2 A three-dimensional diagram of the structure of a stirring reaction tank for a method for preparing nano-scale high-purity active zinc oxide proposed by the present invention;

[0038] Figure 3 A three-dimensional diagram of the sealing disk structure of a method for preparing nano-scale high-purity active zinc oxide proposed by the present invention;

[0039] Figure 4 A method for preparing nano-scale high-purity active zinc oxide proposed by the present invention Figure 3 A magnified view of the structure at center;

[0040] Figure 5 A three-dimensional diagram of the fixed base structure of a method for preparing nano-scale high-purity active zinc oxide proposed by the present invention;

[0041] Figure 6 A three-dimensional diagram of the circulation pump structure of a method for preparing nano-scale high-purity active zinc oxide proposed by the present invention;

[0042] Figure 7 A three-dimensional diagram of the support tube structure of a method for preparing nano-scale high-purity active zinc oxide proposed by the present invention;

[0043] Figure 8 This is a three-dimensional diagram of the sealing locking tube structure of the method for preparing nano-level high-purity active zinc oxide proposed by the present invention.

[0044] In the figure: 1. fixed base; 2. PLC controller; 3. stirring reaction tank; 301. insulation layer; 302. avoidance groove; 303. reflective film; 304. heat conductive layer; 4. sealing door; 5. overflow liquid inlet pipe; 6. electric heater; 601. spiral heating tube; 7. sealing plate; 8. stirring reduction motor; 9. stirring shaft; 10. stirring paddle; 11. collecting hopper; 12. discharge pipe; 13. discharge control valve; 14. circulating feed pipe; 15. circulating pump; 16. supporting pipe; 17. sealing locking pipe; 18. filter pipe; 19. filter net; 20. fixed sealing pipe; 21. reflux pipe; 22. monitoring pipe; 23. temperature sensor; 24. liquid storage barrel; 25. sealing cover; 26. liquid adding pipe; 27. solenoid valve; 28. flow sensor. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0046] Reference Figure 1 , a method for preparing nano-scale high-purity active zinc oxide, comprising the following steps:

[0047] a. Screening: Put the zinc-containing powder into the powder screening barrel of the screening mechanism for screening, and then send the powder into the mixing tank after screening;

[0048] b. Mixing and stirring: Add the leaching liquid into the mixing and stirring tank at the same time. The leaching liquid contains NH 3 and (NH 4 )2SO 4 The mixture with a pH value of 5.0 to 5.5 is mixed with the sieved powder and stirred at room temperature by a mixing barrel stirring mechanism at a stirring speed of 75 to 85 r / min;

[0049] The leaching solution is an ammonia complex containing sulfate, and the process pH value is 4.5-5.2.

[0050] c. Reaction stirring: After the mixed liquid in the mixing and stirring tank enters the reaction stirring device through the overflow port of the mixing and stirring tank, it is heated by the reaction stirring device and stirred for reaction, and the Fe2+ in the zinc sulfate plating solution is oxidized to Fe3+ with a strong oxidant. When the zinc content is 115-125 g / L, the leachate is obtained by sampling and calibration, and the soda solution is added to synthesize and generate a precipitate;

[0051] The temperature during reaction stirring is maintained at 45-55° C. for filtration, the stirring speed is 55-65 r / min, the stirring time is 4-6 hours, and the soda ash solution is added after stirring for 4-6 hours. The soda ash solution uses a 15-21wt% soda ash solution.

[0052] During the reaction stirring, the iron-containing impurities in the wet-process zinc sulfate were removed by ion exchange. By limiting the stirring speed, resin dosage, reaction temperature and exchange time, the influence on the removal rate of iron and aluminum impurities was reduced, and the iron ion removal rate obtained was 75.49%.

[0053] The soda ash solution also uses a 10-23 wt % soda ash solution.

[0054] Further, refer to Figure 1-Figure 8 The reaction stirring device comprises a fixed base 1, on the upper surface of which a PLC controller 2 and a stirring reaction tank 3 are fixedly mounted, a treatment tank is provided on the surface of the stirring reaction tank 3, a sealing door 4 whose surface is plugged into the surface of the stirring reaction tank 3 is hingedly mounted on the inner wall of the treatment tank, and an overflow liquid inlet pipe 5 is fixedly connected to the surface of the stirring reaction tank 3.

[0055] When in use, the overflow liquid inlet pipe 5 is connected to the overflow port on the mixing and stirring tank, so that the mixed liquid in the mixing and stirring tank can enter the stirring reaction tank 3 for stirring reaction.

[0056] Furthermore, when in use, the processing tank is used to process the precipitate and the liquid on the precipitate, so as to facilitate taking out the precipitate from the stirred reaction tank 3, and the sealing door 4 has the characteristic of sealing and insulating the stirred reaction tank 3 during the stirring reaction process.

[0057] An electric heater 6 is fixedly installed on the surface of the stirring reaction tank 3 . The electric heater 6 is electrically connected to the PLC controller 2 via a cable. The electric heater 6 includes a spiral heating tube 601 .

[0058] The inner wall of the stirred reaction tank 3 is fixedly connected with a heat-insulating layer 301, and the surface of the heat-insulating layer 301 is provided with an avoidance groove 302 adapted to the spiral heating tube 601, and the surface of the heat-insulating layer 301 and the inner wall of the avoidance groove 302 are fixedly connected with a reflective film 303, and the surface of the reflective film 303 is provided with a heat-conducting layer 304, and the heat-conducting layer 304 is fixedly connected to the inner wall of the stirred reaction tank 3 by screws.

[0059] The spiral heating tube 601 is disposed in the avoidance groove 302 and between the reflective film 303 and the heat conducting layer 304 .

[0060] The interior of the thermal insulation layer 301 is aerogel felt, and the interior of the heat conductive layer 304 is a metal heat conductive sheet.

[0061] When in use, the electric heater 6 is controlled by the PLC controller 2 to transfer heat to the heat-conducting layer 304 through the spiral heating tube 601, and contacts the liquid inside the stirring reaction tank 3 through the heat-conducting layer 304, thereby heating and stirring the liquid inside the stirring reaction tank 3.

[0062] A sealing disk 7 is fixedly connected to the upper surface of the stirring reaction tank 3 by bolts, and a stirring reduction motor 8 is fixedly installed on the upper surface of the sealing disk 7. The stirring reduction motor 8 is electrically connected to the PLC controller 2 through a cable.

[0063] The inner top wall of the sealing disk 7 is rotatably connected to a stirring shaft 9 via a bearing, and one end of the stirring shaft 9 is fixedly connected to a reduction output end of a stirring reduction motor 8 .

[0064] The other end of the stirring shaft 9 extends to the interior of the stirring reaction tank 3 , and a stirring paddle 10 is fixedly connected to the surface of the stirring shaft 9 . A plurality of stirring paddles 10 are distributed in a ring array on the surface of the stirring shaft 9 with the axis of the stirring shaft 9 as the center.

[0065] When in use, the stirring reduction motor 8 is automatically controlled by the PLC controller 2 to rotate the stirring shaft 9 and the stirring paddle 10 to stir the mixed liquid inside the stirring reaction tank 3, and the stirring speed and stirring time of the stirring reduction motor 8 are automatically controlled by the PLC controller 2.

[0066] The inner wall of the stirred reactor 3 is fixedly connected to the collecting hopper 11, the inner wall of the collecting hopper 11 is conical, and the inner bottom wall of the collecting hopper 11 is fixedly connected to a discharge pipe 12. One end of the discharge pipe 12 passes through and extends to the surface of the stirred reactor 3 and is fixedly installed with a discharge control valve 13.

[0067] The surface of the discharge pipe 12 is fixedly connected to a circulating feed pipe 14 via a three-way pipe, and one end of the circulating feed pipe 14 penetrates and extends to the surface of the stirring reaction tank 3 .

[0068] A circulation pump 15 is fixedly installed on the upper surface of the fixed base 1, and the circulation pump 15 is electrically connected to the PLC controller 2 through a cable. One end of the circulation feed pipe 14 is fixedly connected to the inlet end of the circulation pump 15, and the outlet end of the circulation pump 15 is fixedly connected to a support pipe 16, and a sealing locking pipe 17 is slidably sleeved on the surface of the support pipe 16.

[0069] The surface of the sealing locking tube 17 is T-shaped, and the surface of the sealing locking tube 17 is threadedly connected to the filter tube 18. The inner wall of the filter tube 18 is fixedly connected with a filter screen 19. Multiple filter screens 19 are evenly distributed on the inner wall of the filter tube 18, and the mesh sizes of the multiple filter screens 19 increase from bottom to top.

[0070] Furthermore, in order to achieve better filtering and clean the filter tube 18 after use, a circular pipe check valve is fixedly installed on the inner wall of the filter tube 18, and the circular pipe check valve is fixedly installed below the multiple filter screens 19. This prevents the impurities intercepted and filtered by the filter screens 19 from falling into the support tube 16 and the circulation pump 15, causing blockage and inconvenience in cleaning.

[0071] One end of the filter tube 18 is threadedly connected to a fixed sealing tube 20 , the surface of the fixed sealing tube 20 is T-shaped, and both ends of the filter tube 18 are provided with rubber sealing rings whose surfaces are plugged into the surfaces of the sealing locking tube 17 and the fixed sealing tube 20 .

[0072] One end of the fixed sealing tube 20 is fixedly connected to a reflux pipe 21, one end of the reflux pipe 21 penetrates and extends to the interior of the stirred reaction tank 3, the surface of the reflux pipe 21 is fixedly connected to a monitoring tube 22, a temperature sensor 23 is fixedly installed on the inner wall of the monitoring tube 22, and the temperature sensor 23 is electrically connected to the PLC controller 2 through a cable.

[0073] Furthermore, when in use, the temperature of the liquid in the reflux pipe 21 is monitored by the temperature sensor 23 , thereby achieving the effect of monitoring the stirring temperature inside the stirring reaction tank 3 .

[0074] The lower surface of the sealing disk 7 is fixedly connected to the liquid storage barrel 24 , one end of the liquid storage barrel 24 penetrates and extends to the upper surface of the sealing disk 7 , and the surface of the liquid storage barrel 24 is hingedly mounted with the sealing cover 25 .

[0075] Furthermore, the liquid storage barrel 24 is arranged in the stirring reaction tank 3, which not only has the effect of automatically adding the soda ash solution to generate a precipitate during the stirring reaction process, but also has the effect of keeping the temperature of the soda ash solution consistent with the temperature of the mixed liquid during the heating and stirring reaction of the mixed liquid, thereby achieving a better effect of generating a precipitate.

[0076] A liquid adding pipe 26 is fixedly connected to the inner bottom wall of the liquid storage barrel 24 , one end of which passes through and extends to the upper surface of the sealing disk 7 , and one end of the liquid adding pipe 26 is fixedly connected to the inner wall of the circulating feed pipe 14 through a three-way pipe.

[0077] When in use, the liquid adding pipe 26 is connected to the circulating feed pipe 14 through a three-way pipe. The liquid in the liquid storage barrel 24 is sucked into the reflux pipe 21 by the circulating pump 15, and then enters the stirring reaction barrel through the reflux pipe 21.

[0078] A solenoid valve 27 and a flow sensor 28 are fixedly mounted on the surface of the liquid adding pipe 26 , respectively. Both the solenoid valve 27 and the flow sensor 28 are electrically connected to the PLC controller 2 via cables.

[0079] Specifically, the solenoid valve 27 is used to control the connection and disconnection between the liquid adding pipe 26 and the circulating feed pipe 14 , and the flow sensor 28 is used to monitor the flow rate of the liquid storage barrel 24 flowing out through the liquid adding pipe 26 .

[0080] Specifically, the working principle of the reaction stirring device is:

[0081] The mixed liquid in the mixing and stirring tank enters the overflow liquid inlet pipe 5 through the overflow port on the mixing and stirring tank, and then enters the stirring reaction tank 3, and then the soda ash solution is added into the liquid storage barrel 24, and then the control program of the PLC controller 2 is set, and the PLC controller 2 automatically controls the electric heater 6 and the stirring reduction motor 8 to work, and the electric heater 6 heats the stirring reaction tank 3 through the spiral heating tube 601, and the heat on the spiral heating tube 601 is transferred to the mixed liquid through the heat conductive layer 304, so as to heat the mixed liquid.

[0082] The reduction output end of the stirring reduction motor 8 drives the stirring shaft 9 to rotate, and the stirring shaft 9 drives multiple stirring paddles 10 to rotate, so as to stir and heat the mixed liquid for reaction. At the same time, the PLC controller 2 controls the circulation pump 15 to work, and the inlet end of the circulation pump 15 sucks the mixed liquid through the circulation feed pipe 14, and then pumps it out through the outlet end of the circulation pump 15 into the support pipe 16, and then enters the filter tube 18, and the mixed liquid is filtered by multiple filter screens 19 inside the filter tube 18. The mixed liquid filtered by the filter screen 19 enters the stirring reaction tank 3 through the reflux pipe 21, and continues to stir and react. During the stirring reaction, the mixed liquid is extracted by the circulation pump 15, and then enters the stirring reaction tank 3 after filtering, so as to realize stirring and filtering of impurities in the mixed liquid, and at the same time, the mixed liquid flows out from the bottom of the stirring reaction tank 3 and flows in from the top, so as to realize circulating flow and accelerate reaction stirring.

[0083] The temperature of the mixed liquid in the stirring reaction tank 3 is monitored by the temperature sensor 23 arranged in the monitoring tube 22, and the monitoring data is fed back to the PLC controller 2 in real time, so that the PLC controller 2 can automatically control the operation of the electric heater 6 to achieve automatic temperature control, and the speed and working time of the stirring reduction motor 8 can be automatically controlled by the PLC controller 2 to achieve automatic control of the speed and stirring reaction time of the stirring reaction.

[0084] Finally, after the stirring is completed, the PLC controller 2 automatically controls the solenoid valve 27 on the liquid adding pipe 26 to open. During the operation of the circulation pump 15, suction is generated on the liquid adding pipe 26, and the soda ash solution inside the liquid storage barrel 24 is sucked into the circulating feed pipe 14 through the liquid adding pipe 26, pumped into the support pipe 16 and the filter pipe 18, and refluxed into the stirring reaction tank 3 through the reflux pipe 21 to participate in the stirring reaction. At the same time, the soda ash solution is monitored by the flow sensor 28. After reaching the set value, the PLC controller 2 automatically controls the solenoid valve 27 to close, and then, according to the program setting, the circulation pump 15 is first controlled to stop working, and then the stirring reduction motor 8 is controlled to stop working, waiting for the soda ash solution and the mixed liquid to generate a precipitate, and finally the electric heater 6 is controlled to stop working.

[0085] By setting up a reaction stirring device, when in use, the mixed liquid is stirred by automatically controlling the temperature, and during the stirring reaction process, the mixed liquid is extracted from the stirring reaction tank 3 and filtered, and the filtered mixed liquid is refluxed into the stirring reaction tank 3 again, so as to accelerate the flow of the mixed liquid inside the tank body and achieve better stirring reaction. Finally, the soda ash solution in the liquid storage barrel 24 is automatically controlled by the PLC controller 2 to enter the stirring reaction tank 3 to generate a precipitate, thereby realizing full-process automatic control and achieving a better effect of preparing nano zinc oxide.

[0086] Furthermore, the zinc sulfate solution reacts fully with the soda ash solution and almost all of the raw materials are reacted, thus avoiding the introduction of more impurities.

[0087] Furthermore, since the zinc sulfate solution and the soda ash solution react at 55-65° C., the obtained nano zinc oxide particles have a large specific surface area. At this temperature, the reaction degree of zinc sulfate and soda ash can also be increased to recover zinc to the greatest extent.

[0088] d. Precipitation drying: The precipitate is filtered, and after the filter cake is dried, the classification particle size is controlled to 200 meshes, and after drying again, it is screened through a vibrating screen with a mesh number of 325 meshes; during the precipitation drying, the filter cake drying temperature of the precipitation filter press is set to 300-350℃;

[0089] During precipitation drying, the filter cake drying temperature of the precipitation filter press is also set to 350-400°C.

[0090] e. Calcination and grinding: The dried and screened product is returned to the brick kiln for calcination for 1 hour via adjustable electricity to generate highly active zinc oxide. The calcination temperature is 600-700°C.

[0091] Furthermore, the powdered product after drying and screening is calcined at a temperature of 600-700° C. The calcination temperature is lowered by the preliminary process before calcination. At the same time, under this temperature condition, the agglomeration of nano zinc oxide particles and the reduction of specific surface area caused by temperature are avoided. By selecting the calcination temperature, the specific surface area of ​​nano zinc oxide is maximized, and at the same time, a small amount of basic zinc carbonate can be contained in the nano zinc oxide, and its surface activity is much higher than that of the product obtained by directly mixing nano zinc oxide and basic zinc carbonate in proportion.

[0092] Through the above technical solution, the zinc oxide content of the obtained active nano zinc oxide is 92% and the specific surface area is 120m 2 / g.

[0093] For details, refer to the following table: implementation conditions and product test results of Examples 1-5 and Comparative Examples 1-4.

[0094]

[0095] In comparative example 1, the pH value of the leaching solution during mixing and stirring is specially set to 5.5; the stirring of the reaction tank is specially set to be maintained at 45-55° C. for filtration; other conditions refer to conventional operations.

[0096] Comparative Example 2: A 15 wt % soda ash solution is specially added; other conditions refer to conventional operation.

[0097] Comparative Example 3: The drying temperature of the leached filter cake was specially set to 300°C; other conditions were referred to conventional operations.

[0098] Comparative Example 4: Refer to conventional operation.

[0099] It can be seen from the test data in the above table that when the pH value of the leaching liquid is added to the process during stable mixing and stirring, or when the stirring reaction temperature of the reaction tank is high, or when a higher concentration of soda ash is used for the preparation operation, or when the drying temperature of the leached filter cake is high, the quality of the zinc oxide content will be improved, and the product will have a larger specific surface area and lower iron impurities.

[0100] By setting up an ion exchange method to remove iron-containing impurities in wet-process zinc sulfate, the leaching process and the technical conditions controlled during the operation are improved, so that the zinc in the raw material can be completely dissolved into the solution to the greatest extent during the leaching process, and some iron impurities can be removed after the leaching displacement reaction. The output of the leaching product is affected by the selection of the leaching solution, and the sedimentation rate, filtration performance, and whether it is easy to separate liquid and solid are also affected.

[0101] By setting steps a, b, c, d and e, basic zinc carbonate contained in the prepared zinc oxide is used as an active zinc oxide carrier to improve the reaction interface of nano zinc oxide. When the pH value of the leaching solution is added during stable mixing and stirring, or when the stirring reaction temperature of the reaction tank is high, or when a higher concentration of soda ash is used for the preparation operation, or when the drying temperature of the leached filter cake is high, the quality of the zinc oxide content is improved and the zinc oxide has a larger specific surface area.

[0102] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing nano-scale high-purity active zinc oxide, characterized in that: The following steps are involved: a. Screening: Put the zinc-containing powder into the powder screening barrel of the screening mechanism for screening, and then send the powder into the mixing tank after screening; b. Mixing and stirring: Add the leaching solution into the mixing and stirring tank at the same time. The leaching solution is a mixture containing NH3 and (NH4)2SO4 and having a pH value of 5.0 to 5.5, and mix it with the sieved powder. At the same time, stir it at room temperature through the mixing barrel stirring mechanism, and the stirring speed is 75 to 85 r / min; c. Reaction stirring: After the mixed liquid in the mixing and stirring tank enters the reaction stirring device through the overflow port of the mixing and stirring tank, it is heated by the reaction stirring device and stirred for reaction, and the Fe2+ in the zinc sulfate plating solution is oxidized to Fe3+ with a strong oxidant. When the zinc content is 115-125 g / L, the leachate is obtained by sampling and calibration, and the soda solution is added to synthesize and generate a precipitate; d. Precipitation and drying: The precipitate is filtered, and after the filter cake is dried, the particle size is controlled to 200 meshes, and after drying again, it is screened through a vibrating screen with a mesh number of 325 meshes; e. Calcination and grinding: The dried and screened product is returned to the brick kiln for calcination for 1 hour via adjustable electricity to produce highly active zinc oxide.

2. A method for preparing nano-scale high-purity active zinc oxide according to claim 1, characterized in that: The leaching liquid in the mixed stirring is an ammonia complex containing sulfate, the process pH value is 4.5-5.2, the temperature in the reaction stirring is maintained at 45-55°C for filtration, the stirring speed is 55-65r / min, the stirring time is 4-6 hours, and the soda ash solution is added after stirring for 4-6 hours, and the soda ash solution uses a 15-21wt% soda ash solution.

3. A method for preparing nano-scale high-purity active zinc oxide according to claim 1, characterized in that: The soda ash solution also uses a 10-23wt% soda ash solution.

4. The method for preparing nano-scale high-purity active zinc oxide according to claim 1, characterized in that: In the precipitation drying, the filter cake drying temperature of the precipitation filter press is set to 300-350°C; In the precipitation drying, the filter cake drying temperature of the precipitation filter pressing is also set to 350-400°C, and the calcination temperature is 600-700°C.

5. The method for preparing nano-scale high-purity active zinc oxide according to claim 1, characterized in that: The reaction stirring device comprises a fixed base (1), a PLC controller (2) and a stirring reaction tank (3) are fixedly mounted on the upper surface of the fixed base (1), a treatment tank is arranged on the surface of the stirring reaction tank (3), a sealing door (4) is hingedly mounted on the inner wall of the treatment tank, and the surface of the sealing door (4) is plugged into the surface of the stirring reaction tank (3), and an overflow liquid inlet pipe (5) is fixedly connected to the surface of the stirring reaction tank (3); An electric heater (6) is fixedly mounted on the surface of the stirred reaction tank (3), the electric heater (6) is electrically connected to the PLC controller (2) via a cable, and the electric heater (6) comprises a spiral heating tube (601); The inner wall of the stirred reaction tank (3) is fixedly connected with a heat-insulating layer (301), the surface of the heat-insulating layer (301) is provided with an avoidance groove (302) adapted to the spiral heating tube (601), the surface of the heat-insulating layer (301) and the inner wall of the avoidance groove (302) are both fixedly connected with a reflective film (303), the surface of the reflective film (303) is provided with a heat-conducting layer (304), and the heat-conducting layer (304) is fixedly connected to the inner wall of the stirred reaction tank (3) by means of screws; The spiral heating tube (601) is arranged in the avoidance groove (302) and between the reflective film (303) and the heat-conducting layer (304); The interior of the thermal insulation layer (301) is aerogel felt, and the interior of the heat conductive layer (304) is a metal heat conductive sheet.

6. A method for preparing nano-scale high-purity active zinc oxide according to claim 5, characterized in that: The upper surface of the stirring reaction tank (3) is fixedly connected to a sealing disk (7) by bolts, and the upper surface of the sealing disk (7) is fixedly installed with a stirring reduction motor (8), and the stirring reduction motor (8) is electrically connected to the PLC controller (2) through a cable; The inner top wall of the sealing disk (7) is rotatably connected to a stirring shaft (9) via a bearing, and one end of the stirring shaft (9) is fixedly connected to the reduction output end of the stirring reduction motor (8); The other end of the stirring shaft (9) extends into the interior of the stirring reaction tank (3); a stirring paddle (10) is fixedly connected to the surface of the stirring shaft (9); a plurality of stirring paddles (10) are distributed in a ring array on the surface of the stirring shaft (9) with the axis of the stirring shaft (9) as the center.

7. A method for preparing nano-scale high-purity active zinc oxide according to claim 6, characterized in that: The inner wall of the stirring reaction tank (3) is fixedly connected to a collecting hopper (11), the inner wall of the collecting hopper (11) is in a conical shape, the inner bottom wall of the collecting hopper (11) is fixedly connected to a discharge pipe (12), one end of the discharge pipe (12) penetrates and extends to the surface of the stirring reaction tank (3) and is fixedly installed with a discharge control valve (13); The surface of the discharge pipe (12) is fixedly connected to a circulating feed pipe (14) via a three-way pipe, and one end of the circulating feed pipe (14) penetrates and extends to the surface of the stirring reaction tank (3); A circulation pump (15) is fixedly mounted on the upper surface of the fixed base (1), and the circulation pump (15) is electrically connected to the PLC controller (2) via a cable. One end of the circulation feed pipe (14) is fixedly connected to the inlet end of the circulation pump (15), and the outlet end of the circulation pump (15) is fixedly connected to a support pipe (16), and a sealing locking pipe (17) is slidably sleeved on the surface of the support pipe (16).

8. The method for preparing nano-scale high-purity active zinc oxide according to claim 7, characterized in that: The surface of the sealing locking tube (17) is in a T shape, the surface of the sealing locking tube (17) is threadedly connected to the filter tube (18), the inner wall of the filter tube (18) is fixedly connected with a filter screen (19), a plurality of filter screens (19) are evenly distributed on the inner wall of the filter tube (18), and the mesh sizes of the plurality of filter screens (19) increase from bottom to top; A circular pipeline check valve is fixedly installed on the inner wall of the filter tube (18), and the circular pipeline check valve is fixedly installed below the plurality of filter screens (19); One end of the filter tube (18) is threadedly connected to a fixed sealing tube (20), the surface of the fixed sealing tube (20) is in a T shape, and both ends of the filter tube (18) are provided with rubber sealing rings whose surfaces are plugged into the surfaces of the sealing locking tube (17) and the fixed sealing tube (20).

9. The method for preparing nano-scale high-purity active zinc oxide according to claim 8, characterized in that: One end of the fixed sealing tube (20) is fixedly connected to a reflux tube (21), one end of the reflux tube (21) penetrates and extends into the interior of the stirring reaction tank (3), the surface of the reflux tube (21) is fixedly connected to a monitoring tube (22), a temperature sensor (23) is fixedly installed on the inner wall of the monitoring tube (22), and the temperature sensor (23) is electrically connected to the PLC controller (2) via a cable.

10. The method for preparing nano-scale high-purity active zinc oxide according to claim 9, characterized in that: The lower surface of the sealing disk (7) is fixedly connected to a liquid storage barrel (24), one end of the liquid storage barrel (24) penetrates and extends to the upper surface of the sealing disk (7), and the surface of the liquid storage barrel (24) is hingedly mounted on a sealing cover (25); The inner bottom wall of the liquid storage barrel (24) is fixedly connected with a liquid adding pipe (26), one end of the liquid adding pipe (26) penetrates and extends to the upper surface of the sealing disk (7), and one end of the liquid adding pipe (26) is fixedly connected with the inner wall of the circulating feed pipe (14) through a three-way pipe; A solenoid valve (27) and a flow sensor (28) are respectively fixedly mounted on the surface of the liquid adding pipe (26), and the solenoid valve (27) and the flow sensor (28) are both electrically connected to the PLC controller (2) via cables.

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