A method and apparatus for preparing 4bs seed crystals

Abstract

The application relates to a preparation method and device of 4BS crystal seeds, which comprises the following steps: putting pure water into a reaction kettle, stirring and heating, then adding dilute sulfuric acid and mixing uniformly; then adding lead powder into the reaction kettle at a constant speed, and stirring and reacting; the mass ratio of the lead powder to the dilute sulfuric acid is (2.3-5.9):1; the lead powder contains lead oxide; filtering the solution after the reaction, drying the obtained filter cake to obtain 4BS crystal seeds. According to the application, the sulfuric acid is first added and dispersed uniformly in the reaction kettle, then the lead powder is added under the condition of constant temperature stirring to react, the reaction uniformity is better, high-purity crystal seeds can be produced, the purity is more than 98%, the grain size is not more than 8 mu m, and the distribution is uniform.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lead and lead products, and particularly relates to a preparation method and device of 4BS crystal seeds. BACKGROUND

[0002] With the increasing degree of electrification and automation of automobiles, the energy load borne by the battery is increasing, and the function of the battery is no longer just to bear the conventional starting lighting ignition; the discharge depth of the storage battery is as high as 50% or even 100%. With the increase of the discharge depth, the positive lead paste quickly appears to be muddy and fails, resulting in premature failure of the battery life. By adding 4BS (tetraalkali lead sulfate) crystal seeds in the lead paste, the uniformity of the crystal seeds is beneficial to the uniform formation and distribution of 4BS in the positive lead paste, and has the effect of stably controlling the size of 4BS in the solidification stage. 4BS plays a role of framework during the cycle life, avoids the muddy failure of the lead paste during the cycle life, and thus improves the cycle life of the battery. At the same time, since the price of 4BS is several times that of lead and lead oxide, the deep processing of lead products is beneficial to the improvement of the value of lead products.

[0003] Currently, the preparation process of 4BS usually is that the lead material is first sent into a reaction kettle, and then sulfuric acid is added for reaction, but this process can cause the lead material to easily agglomerate, resulting in uneven 4BS and large particle size; for example, the preparation process of patent CN109052458A for preparing nano-level tetraalkali lead sulfate crystal seeds from waste lead storage batteries, wherein the hydrothermal reaction for preparing tetraalkali lead sulfate disclosed in the patent is adopted. In order to avoid the agglomeration of the lead material, various additives such as slow-release control agent, crystal form control agent and anti-agglomeration control agent are added. In order to overcome this problem, patent CN106564941A adopts the scheme of pre-mixing the lead material and adding concentrated sulfuric acid, but the pre-mixing of the lead material takes a long time, and the lead material needs to be stirred for 0.5-1h before being added into the reaction kettle. In addition, although the addition of concentrated sulfuric acid can rapidly increase the reaction temperature, the local concentration and temperature are too high when the concentrated sulfuric acid is added, which can result in too many impurities in the generated 4BS and uneven particle size distribution.

[0004] Therefore, the temperature and the uniformity of the reaction in the preparation process of 4BS can affect the product quality, especially the uniformity and purity of the product, and therefore it is necessary to provide a preparation method and device of 4BS with better uniformity and consistency. SUMMARY

[0005] The purpose of the present application is to overcome the above technical deficiencies, and to provide a preparation method and device of 4BS crystal seeds, which solve the technical problem that the uniformity and purity of the 4BS crystal seeds cannot be improved simultaneously in the prior art.

[0006] In order to achieve the above technical purposes, the technical scheme adopted by the present application is as follows:

[0007] In a first aspect, the present application provides a preparation method of 4BS crystal seeds, comprising the following steps:

[0008] (1) Put pure water into the reaction kettle, stir and heat, and then add dilute sulfuric acid and mix uniformly;

[0009] (2) Uniformly add lead powder into the reaction kettle, and stir and react; the mass ratio of the lead powder to the dilute sulfuric acid is (2.3-5.9):1; the lead powder contains lead oxide;

[0010] (3) Filter the reacted solution, dry the obtained filter cake, and obtain 4BS crystal seeds.

[0011] In a second aspect, the present application provides a device for preparing the above-mentioned 4BS crystal seeds, comprising a heating device, a reaction kettle device, and a drying device; wherein the reaction kettle device mainly comprises a reaction kettle, a motor, and a stirring paddle; the reaction kettle comprises a conical kettle bottom, a kettle body, and a kettle top arranged in sequence from bottom to top; a plurality of material inlets are arranged on the kettle top, and a crystal slurry outlet is arranged at the bottom of the conical kettle bottom; the motor is arranged at the top of the kettle top, and the stirring paddle is arranged in the reaction kettle and connected with the motor; the motor is used to drive the stirring paddle to stir the solution in the reaction kettle; the heating device is used to heat and keep warm the reaction kettle; and the drying device is used to dry the crystal slurry to obtain 4BS crystal seeds.

[0012] Compared with the prior art, the present application has the following beneficial effects:

[0013] (1) The preparation method of the present application is simple; by first adding sulfuric acid to disperse uniformly in the reaction kettle, and then adding lead powder, the temperature rise caused by the addition of sulfuric acid is avoided to cause uneven crystal grain size; by adding lead powder to react under constant temperature stirring, the reaction uniformity is better, and high-purity crystal seeds (more than 98%) can be produced; and by controlling the uniform feeding of lead powder and the mass ratio of lead powder to dilute sulfuric acid, the agglomeration of raw materials to cause the increase of crystal grain size is avoided, and the crystal grain size of the present application is not more than 8 μm and is uniformly distributed;

[0014] (2) The present application develops a reaction device for rapidly preparing 4BS; the reaction kettle is heated and kept warm by the heating device, and the solution in the reaction kettle is stirred by the motor driving the stirring paddle; the reaction slurry does not deposit and does not stratify; a uniform suspension liquid is formed to promote the uniform reaction, avoid the formation of large particle crystals or local high concentration to cause the generation of 1BS or 3BS, greatly improve the production efficiency, and obtain more uniform products with better consistency; at the same time, the reaction device has small floor area, high production efficiency, and simple manual operation. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a structural schematic view of the reaction kettle and the heating tank of the device of the present application;

[0016] Figure 2 The structure diagram of the reaction kettle of the device of the present application is shown in the figure;

[0017] Figure 3 The structure diagram of the stirring paddle arranged inside the reaction kettle is shown in the figure;

[0018] 1-hot water tank, 101-automatic water supply port;

[0019] 201-hot water outlet, 202-circulating pump, 203-first inlet, 204-first outlet, 205-second inlet, 206-second outlet, 207-backwater inlet;

[0020] 3-reaction kettle, 301-conical kettle bottom, 302-kettle body, 303-kettle top, 304-material inlet, 305-crystal slurry outlet;

[0021] 4-motor;

[0022] 5-stirring paddle, 501-main shaft, 502-assistant stirring shaft, 503-spiral stirring blade, 504-umbrella-shaped blade

[0023] Figure 4 The process flow chart of the preparation of 4BS crystal seeds of the present application is shown in the figure;

[0024] Figure 5 The XRD pattern of the product obtained in Example 1 of the present application is shown in the figure;

[0025] Figure 6 The SEM electron microscope pattern of the 4BS crystal seeds obtained in Example 1 of the present application is shown in the figure. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the figures and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0027] Referring to Figures 1 to 3 The present application provides a reaction device for rapidly preparing 4BS, which comprises a heating device, a reaction kettle device and a drying device.

[0028] The heating device mainly comprises a hot water tank 1 and a circulating pipeline, the circulating pipeline is connected with the hot water tank 1 to form a circulating loop, which is used for heating and heat preservation of the reaction kettle; the reaction kettle device mainly comprises a reaction kettle 3, a motor 4 and a stirring paddle 5.

[0029] The hot water tank 1 uses circulating water; the hot water tank 1 heats the circulating water through an internal electric heating pipe, and the heating temperature range of the circulating water can reach 20-100℃, which can meet the preheating temperature and reaction temperature required in the preparation of 4BS.

[0030] As shown in Figure 1 , the hot water tank 1 is provided with an automatic water replenishing port 101, which can automatically replenish water when the liquid level of the hot water tank 1 is insufficient.

[0031] The hot water tank 1 is provided with a hot water outlet 201 at the bottom and a return water inlet 207 at the top; a circulating pump 202 is arranged on the circulating pipeline, the inlet end of the circulating pipeline is connected with the hot water outlet 201, and the outlet end is connected with the return water inlet 207, forming a circulating loop.

[0032] Preferably, referring to Figure 2 , the reaction kettle 3 comprises a conical kettle bottom 301, a cylindrical kettle body 302 and a kettle top 303 arranged in sequence from bottom to top; the lower side of the conical kettle bottom 301 is provided with a first inlet 203, and the upper side of the conical kettle bottom 301 is provided with a first outlet 204; the lower side of the kettle body 302 is provided with a second inlet 205, and the upper side of the kettle body 302 is provided with a second outlet 206.

[0033] The hot water outlet 201, the circulating pump 202, the first inlet 203, the first outlet 204, the second inlet 205, the second outlet 206 and the return water inlet 207 are sequentially connected, forming a circulating loop.

[0034] It can be understood that, here, "first" and "second" are only used to distinguish the positions of the circulating water outlets and inlets, and are not intended to limit the number and sequence of the circulating water outlets and inlets in the present application.

[0035] The reaction kettle 3 can be of various types, which can be selected by those skilled in the art according to needs, and is not specifically limited here; for example, the reaction kettle can be a jacketed reaction kettle or a coil type reaction kettle, and the circulating loop only needs to ensure that it can uniformly heat and insulate the reaction kettle.

[0036] As a preferred embodiment, in the present application, the heated circulating water is pumped into the first inlet 203 of the conical kettle bottom 301 by the circulating pump 202; the circulating water exchanges heat with the external heat of the conical kettle bottom 301 and the heat of the solution inside the conical kettle bottom 301, achieving initial heating and constant temperature control of the solution in the conical kettle bottom. The hot circulating water enters the second inlet 205 of the kettle body 302 through the first outlet 204 of the conical kettle bottom 301, achieving reutilization of heat energy, and the circulating hot water heats and warms up the reaction kettle 3, and finally the circulating water returns to the hot water tank 1 through the second outlet 206 at the upper part of the kettle body 302 to be reheated.

[0037] The kettle top 303 of the reaction kettle 3 is provided with a plurality of material inlets 304 at the upper part, for automatic feeding of materials such as acid, water solution, lead and lead oxide.

[0038] The bottom of the conical kettle bottom 301 is provided with a crystal slurry outlet 305, and the reaction generated crystal slurry solution is discharged from the bottom outlet of the reaction kettle to the next process drying.

[0039] The top of the kettle top 303 of the reaction kettle 3 is provided with a motor 4, and the reaction kettle 3 is coaxially provided with a stirring paddle 5; the motor 4 drives the stirring paddle to stir the solution.

[0040] Preferably, the stirring paddle 5 adopts a composite type spiral stirring paddle.

[0041] Referring to Figure 3 , the stirring paddle 5 mainly comprises a main shaft 501, an auxiliary stirring shaft 502, a spiral stirring blade 503 and an umbrella-shaped blade 504 at the bottom. The spiral stirring blade 503 is arranged on the shaft of the main shaft 501, the umbrella-shaped blade 504 is arranged at the lower end of the main shaft 501, the auxiliary stirring shaft 502 is connected with the main shaft 501 and the spiral stirring blade 503; the upper end of the main shaft is connected with the motor.

[0042] The main shaft 501 is driven by the motor 4, the main shaft 501 drives the auxiliary stirring shaft 502 and the spiral stirring blade 503, the width of the spiral stirring blade 503 is 10-50cm, the thickness is 5-15mm, the distance between the outermost edge of the spiral stirring blade 503 and the inner wall of the reaction kettle is ≤10mm, which prevents the reaction material from depositing on the inner wall of the reaction kettle.

[0043] The main shaft 501 is designed with an umbrella-shaped blade 504, the inclination angle of the umbrella-shaped blade 504 relative to the main shaft axis is 30-90℃, the number is 3-6, the length is 30-60cm, and the width is 5-20mm. The lowermost end of the umbrella-shaped blade 504 is located in the conical kettle bottom 301 and close to the bottom, which prevents the reaction slurry from sinking to the bottom.

[0044] The present application can realize uniform stirring of the reaction slurry by driving the composite stirring paddle with the motor, and the reaction slurry does not deposit and stratify; a uniform suspension can be formed to promote uniform reaction, and the formation of large particle crystals or local high concentration to generate 1BS or 3BS is avoided.

[0045] Preferably, the rotating speed of the stirring motor in the present application can be controlled at 0-50r / min, for example, 5r / min, 10r / min, 15r / min, 20r / min, 25r / min, 30r / min, 35r / min, 40r / min, 45r / min or 50r / min, which can be set according to the reaction needs.

[0046] The drying device in the present application can be selected in a wide range, which is not limited here.

[0047] The reaction device of the present application has small floor area, high production efficiency, uniform and stable reaction, and high purity of the produced product.

[0048] The application also provides a preparation method of 4BS crystal seeds, which can quickly produce high-purity 4BS crystal seeds, has a simple whole process flow, no redundant acid water discharge, high 4BS yield and environmental protection and easy process production.

[0049] Referring to Figure 4 The preparation method specifically comprises the following steps:

[0050] Solution addition: 600-1000 kg of pure water or filtered filtrate is added to the reaction kettle, the reaction kettle is internally provided with a stirrer, and the stirring speed can be adjusted at 0-30 revolutions / minute; for example, no stirring is performed when pure water is initially used;

[0051] Solution heating: the solution in the reaction kettle is stirred at a speed of 10-15 revolutions / minute, and the solution in the reaction kettle is continuously heated to 30°C while stirring;

[0052] Sulfuric acid addition process: 60-120 kg of sulfuric acid (the mass ratio of sulfuric acid addition amount to solution addition is 0.06-0.2, preferably 0.1-0.2) is added to the reaction kettle, the mass concentration of the sulfuric acid is 35-48%, and the reaction kettle temperature is maintained at 30-50°C during the process;

[0053] Feeding process: 280-350 kg of lead powder containing 70-90 wt% of lead oxide and 10 wt%-30 wt% of lead is fed into the reaction kettle (the mass ratio of the lead and lead oxide mixture to sulfuric acid is controlled to be (2.3-5.9):1, preferably (3-5):1), the reaction kettle continues to be stirred, and the feeding is uniformly performed within 20-50 minutes, and the reaction is performed for 1-4 hours after the feeding is completed;

[0054] Filtering crystal seeds: the reacted solution is filtered, and the filtered cake is the required 4BS crystal seeds, and the filtrate is directly returned to the reaction kettle.

[0055] Drying process: the filtered cake is baked at a high temperature of 250-300°C for 2-5 hours to obtain the 4BS crystal seeds.

[0056] The application will be further described in detail through specific examples.

[0057] Example 1

[0058] (1) 600 kg of pure water is added to the reaction kettle, and 80 kg of sulfuric acid with a concentration of 42% is added after being heated to 30°C, and the mixture is uniformly stirred at a stirring speed of 10-15 revolutions / minute;

[0059] (2) 320 kg of lead powder containing 80% of lead oxide is further added to the reaction kettle, and the reaction is continuously stirred at 40°C for 30 minutes;

[0060] (3) The reacted solution is filtered, the obtained filter cake is baked at 280℃ for 3h to obtain 4BS crystal seeds; the obtained filtrate can be directly returned to the reaction kettle to replace an equal amount of pure water, in which case stirring is required.

[0061] Figure 5 The XRD pattern of the obtained product is compared with a standard color card, and the main characteristic peaks are consistent, indicating that the product is 4BS crystal seeds; Figure 6 The SEM electron microscope pattern of the obtained 4BS crystal seeds is a uniformly distributed rod-shaped crystal structure, and the crystal particle size is not more than 8um.

[0062] The test shows that the water content in the obtained 4BS crystal seeds is 0.13%, and the purity of the produced 4BS crystal seeds is as high as 99.1%.

[0063] Example 2 (influence of reaction temperature)

[0064] Example 2 differs from Example 1 only in that the reaction temperature of step (2) is adjusted to 20℃, 30℃, 50℃ and 60℃ respectively, and other steps and conditions are the same as those of Example 1.

[0065] It is found that the reaction temperature of 20℃ basically does not generate 4BS, and when the temperature is too high, such as more than 60℃, the produced 4BS crystal agglomerates, and the product particle size ranges from 0.5um to 16um, and the particle size distribution is wide. Therefore, the preferred reaction temperature of the present application is 30-50℃.

[0066] Example 3 (influence of reaction time)

[0067] Example 3 differs from Example 1 only in that the reaction time of step (2) is adjusted to 10min, 20min, 50min and 60min respectively, and other steps and conditions are the same as those of Example 1.

[0068] It is found that when the reaction time is too short, the crystal has not yet completely formed a rod-shaped crystal structure, and about 10% of the crystal is still in a granular structure, and when the reaction time exceeds 60min, the product morphology has no obvious change, therefore, the preferred reaction time of the present application is 20-50min.

[0069] Example 4 (influence of raw material amount)

[0070] Example 4 differs from Example 1 only in that the mass ratio of the amount of sulfuric acid added and the solution added in step (1) is adjusted to 0.05, 0.1, 0.2 and 0.25, and other steps and conditions are the same as those of Example 1.

[0071] The results show that when the adding amount of sulfuric acid and the mass of solution addition are 0.25, the size of the produced 4BS crystal reaches about 20 um, the coarse crystal particle size affects the battery performance; when the adding amount of sulfuric acid and the mass of solution addition are 0.05, the main content of the produced 4BS is only 88%, therefore, the adding amount of sulfuric acid and the mass of solution addition are preferably 0.1-0.2.

[0072] Comparative Example 1 (influence of process sequence is investigated)

[0073] The difference between Comparative Example 1 and Example 1 is only that the adding sequence of sulfuric acid and lead powder is adjusted, i.e., the lead powder is added first, and then the sulfuric acid is added, and the other steps and conditions are the same as those in Example 1.

[0074] The results show that the product appears agglomeration phenomenon.

[0075] In summary, the water content in the 4BS crystal seed obtained by the application is ≤1%, the purity of the produced 4BS crystal seed is as high as more than 98%, and the crystal particle size is not more than 8 um, the particle size is small and the distribution is uniform.

[0076] The specific embodiments of the application described above do not constitute a limitation on the protection scope of the application. Any various other corresponding changes and modifications made according to the technical concept of the application shall be included in the protection scope of the claims of the application.

Claims

1. A method for preparing 4BS seeds, characterized by, The method comprises the following steps: (1) putting pure water into a reaction kettle, stirring and heating, and then adding dilute sulfuric acid and mixing uniformly; (2) adding lead powder into the reaction kettle at a uniform speed and stirring and reacting; the mass ratio of the lead powder to the dilute sulfuric acid is (2.3-5.9):1; the lead powder contains lead oxide; (3) filtering the solution after reaction, drying the obtained filter cake to obtain 4BS crystal seeds; In step (1), the mass concentration of the dilute sulfuric acid is 35-48%; the mass ratio of the dilute sulfuric acid to the pure water is 0.06-0.2; In step (1), the dilute sulfuric acid is added after heating to 25-35°C; the temperature is maintained at 30-50°C after the dilute sulfuric acid is added; The lead powder is added for 20-50 min; the reaction is carried out for 1-4 h after the lead powder is added completely; In step (3), the obtained filtrate is directly returned to the reaction kettle to replace an equal amount of pure water in step (1); the stirring speed in step (1) is 0-30 r / min; initially, the pure water is not stirred.

2. The method of claim 1, wherein the 4BS seed is prepared by the steps of: In step (2), the lead powder contains 70-90 wt% of lead oxide and 10 wt%-30 wt% of lead.

3. The method for preparing 4BS seed crystals according to claim 1, wherein In step (2), the stirring speed is 10-15 r / min.

4. The method of claim 1, wherein the 4BS seed is prepared by the steps of: In step (3), the drying is carried out at 250-300°C for 2-5 h.

5. The method for preparing 4BS crystal seeds according to claim 1, wherein the preparation device of the method comprises a heating device, a reaction kettle device and a drying device; wherein, the reaction kettle device mainly comprises a reaction kettle, a motor and a stirring paddle; the reaction kettle comprises a conical kettle bottom, a kettle body and a kettle top arranged in sequence from bottom to top, a plurality of material inlets are arranged on the kettle top, and a crystal slurry outlet is arranged at the bottom of the conical kettle bottom; the motor is arranged at the top of the kettle top, the stirring paddle is arranged in the reaction kettle, and the stirring paddle is connected with the motor, and the motor is used for driving the stirring paddle to stir the solution in the reaction kettle; the heating device is used for heating and heat preservation of the reaction kettle; the drying device is used for drying the crystal slurry to obtain 4BS crystal seeds.

6. The method of claim 5, wherein the 4BS seed is prepared by the steps of: the stirring paddle comprises a main shaft, an auxiliary stirring shaft, a spiral stirring blade and an umbrella-shaped blade; the spiral stirring blade is arranged on the main shaft; the umbrella-shaped blade is arranged at the lower end of the main shaft; the auxiliary stirring shaft is connected with the main shaft and the spiral stirring blade; the upper end of the main shaft is connected with the motor; the distance between the outer edge of the spiral stirring blade and the inner wall of the reaction kettle is ≤10 mm; the inclination angle of the umbrella-shaped blade relative to the main shaft axis is 30-90°, and the number of the umbrella-shaped blades is 3-6.

7. The method for preparing 4BS seed crystals according to claim 5, characterized in that: the heating device comprises a hot water tank with a heating pipe; the hot water tank is provided with an automatic water supplementing port; the hot water tank is provided with a hot water outlet and a backwater inlet; the hot water outlet is connected with the backwater inlet through a circulating pipeline; a circulating pump is arranged on the circulating pipeline; the circulating pipeline passes through the conical kettle bottom and the kettle body in sequence.

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