Method and system for continuously extracting and washing crude benzomelamine product

Abstract

The invention provides a method and a system for continuously extracting and washing a crude benzomelamine product. The method comprises the following steps: mixing a crude product solid of benzotripolycyanamide with water to prepare slurry capable of continuously flowing, and continuously feeding in a fluid form; enabling the slurry to be in countercurrent contact with washing water in the turntable extraction tower so as to realize continuous extraction and washing of the crude product of the benzotripolycyanamide; meanwhile, the spiral conveyor is additionally arranged at the bottom of the turntable extraction tower, so that washed benzotripolycyanamide solids can be conveniently settled to the lower part of the turntable extraction tower so as to realize continuous discharging and further to be dried. Compared with traditional intermittent cross-flow washing, the method has the advantages that continuous extraction and washing of crude benzomelamine product solids can be achieved, washing efficiency is improved, washing water is saved, impurities such as benzamide and potassium hydroxide remaining in benzomelamine can be efficiently removed, the ash content and the free alkali content of the product are reduced, and the method is suitable for industrial production. And the purity of the benzotripolycyanamide product is improved.

Description

Technical Field

[0001] The invention relates to the technical field of benzoguanamine purification, and in particular to a method and system for continuous extraction and washing of crude benzoguanamine products. Background Art

[0002] As an important chemical raw material, benzoguanamine is widely used in the production of coatings, plastics, and insulating materials. At present, the industrial production of benzoguanamine mainly uses dicyandiamide and benzonitrile as raw materials, and uses inorganic salts as catalysts to react in alkanol solvents. The product is washed, dehydrated, dried, and sieved to obtain a white crystalline product. However, the product usually contains impurities such as benzamide and potassium hydroxide. The presence of these impurities will not only increase the ash content and free alkali content of the benzoguanamine product, reduce the purity of benzoguanamine, and affect its performance in applications such as coatings, plastics, and insulating materials, but also limit its use in high-end application fields, increase the difficulty and cost of subsequent processing, extend the production cycle, and reduce production efficiency. At the same time, it may cause pollution to the environment and increase safety risks.

[0003] As the material quality and standard requirements become increasingly stringent, the purity requirements for benzoguanamine are also getting higher and higher, and the washing process of benzoguanamine has become an important link in improving the purity of the product. However, the traditional washing process of benzoguanamine has obvious limitations, such as low washing efficiency, poor washing effect, and difficulty in achieving continuous production. These problems directly affect the quality and production efficiency of the final product. The traditional washing process mainly uses a washing kettle for cross-current washing. The washed benzoguanamine crude product solids are added to the washing kettle. After adding a large amount of washing water to the kettle, the washed benzoguanamine crude product solids are contacted with the washing water in an immersion and flushing manner under the stirring of the stirrer. The impurities in the crude product are dissolved in the washing water. After stirring and washing for a certain period of time, the washed material is taken out by suction filtration. This washing process has poor washing effect, and a single washing cannot achieve the ideal washing effect. A large amount of washing water is required and multiple washings are required to obtain a qualified benzoguanamine product. The benzoguanamine after washing needs to be taken out by suction filtration or squeezing before it can be fed again. Continuous washing cannot be achieved, and the washing efficiency is low.

[0004] Therefore, it is urgent to develop a method and system for continuous extraction and washing of crude benzoguanamine products, so as to achieve continuous washing of crude benzoguanamine products and improve the purity of benzoguanamine products. Summary of the invention

[0005] In view of this, the present invention proposes a method and system for continuous extraction and washing of a crude benzoguanamine product, which can realize continuous washing, effectively remove impurities such as benzamide and potassium hydroxide, reduce the ash and free alkali content in the product, improve the washing efficiency of benzoguanamine and the purity of the product, and save washing water.

[0006] In a first aspect, the present invention provides a method for continuous extraction and washing of a crude benzoguanamine product, comprising the following steps:

[0007] Step 1: Slurry preparation

[0008] The solid crude product of benzoguanamine is crushed, mixed with water in a homogenizing device, and stirred to form a slurry;

[0009] Step 2: Continuous extraction and washing

[0010] Pure water is continuously injected from the light phase inlet of the rotary disc extraction tower as the light phase; the slurry of step 1 is continuously injected from the heavy phase inlet of the rotary disc extraction tower as the heavy phase; the heavy phase continuously settles downward, the light phase continuously rises, and after the light phase and the heavy phase are in countercurrent contact, the mixture is continuously stirred in the rotary disc extraction tower for extraction and washing, and the solid settles to the lower part of the rotary disc extraction tower to obtain the washed benzoguanamine;

[0011] Step 3: Discharging

[0012] The benzoguanamine solid in step 2 is settled to the bottom of the rotary disc extraction tower, and the solid is continuously conveyed and discharged by a screw conveyor. The frequency of the screw conveyor is adjusted to change the quality of the solid discharge, so that the solid-liquid interface in the tower is located at the lower part of the rotary disc extraction tower. After the discharge, the benzoguanamine product is dried and dehydrated to obtain the product.

[0013] In the present invention, the crude benzoguanamine product is solid, the particle size of which is greater than 1 mm, and contains impurities such as benzamide and potassium hydroxide.

[0014] On the basis of the above technical solution, preferably, in step 1, the particle size of the crushed benzoguanamine is less than 1 mm.

[0015] By adopting the above technical solution, the washing efficiency and washing effect can be significantly improved, because the smaller particle size increases the contact area between benzoguanamine and the washing liquid, making it easier for the internal impurities to be penetrated and dissolved by the washing liquid, thereby removing the impurities more thoroughly and improving the purity of the product. At the same time, the fine particles help to maintain good fluidity of the material during the continuous washing process, avoid blockage problems caused by excessively large particles, and ensure the smooth progress of the production process. Therefore, by controlling the particle size of benzoguanamine, not only can the quality of the product be improved, but also the stability and reliability of the production process can be enhanced.

[0016] On the basis of the above technical solution, preferably, in step 1, the mass ratio of the benzoguanamine to the water is 1:1-3.

[0017] By adopting the above technical solution, the solid can be made into a slurry with good fluidity, which is also conducive to the dissolution of impurities.

[0018] In the present invention, the crude benzoguanamine solid product is mixed with water to form a slurry. On the one hand, the washed benzoguanamine solid can be brought into contact with the pure water used for washing in advance, thereby increasing the dissolution time of impurities in the solid in water and facilitating the dissolution of the impurities. On the other hand, the problem that the solid has poor fluidity and does not meet the flow sampling requirements of the rotary disc extraction tower is solved. The washed material is continuously flow sampled in the form of a mixed slurry, thereby realizing continuous feeding of solid extraction washing.

[0019] On the basis of the above technical solution, preferably, in step 1, the stirring speed is 50 to 500 r / min.

[0020] More preferably, in step 1, the stirring speed is 100 to 400 r / min.

[0021] On the basis of the above technical solution, preferably, in step 2, the feed flow rate of the slurry is 50 to 5000 kg / h, and the feed flow rate of the pure water is 1 to 10 times the flow rate of the slurry.

[0022] By adopting the above technical solution, it is ensured that each unit flow of benzoguanamine has enough water for full contact and washing, thereby effectively removing impurities. At the same time, the appropriate amount of pure water flow can ensure good fluidity of the material, avoiding the heavy phase material from being unable to settle due to too high a pure water flow, or the incomplete washing due to too low a pure water flow.

[0023] On the basis of the above technical solution, preferably, the stirring speed is 50-500 r / min.

[0024] More preferably, in step 2, the stirring speed is 100 to 400 r / min.

[0025] On the basis of the above technical solution, preferably, in step 3, the use of a screw conveyor to continuously convey the solid benzoguanamine in step 2 comprises:

[0026] The solid discharge mass of benzoguanamine is changed by adjusting the rotation frequency of the screw conveyor, so that the solid-liquid two-phase interface in the rotary disc extraction tower is maintained at the lower part of the rotary disc extraction tower.

[0027] In a second aspect, the present invention relates to a benzoguanamine product obtained by the above extraction and washing method, wherein the total content of ash and free alkali formed by benzamide and impurities in the product does not exceed 0.01%, and the impurity removal rate is not less than 95%.

[0028] In a third aspect, the present invention provides a system for implementing the above-mentioned extraction and washing method, the system comprising a homogenizing device, a feed flow controller, a feed pump, a rotary disc extraction tower, and a screw conveyor connected in sequence;

[0029] The homogenizing device is used to prepare slurry; the feed flow controller is used to control the slurry feed flow;

[0030] A feed pump is provided between the feed flow controller and the rotary disc extraction tower, and the feed pump is used to continuously convey the slurry produced by the homogenization device;

[0031] The rotary disc extraction tower is used for countercurrent contact between the pure water and the slurry to achieve extraction and washing of impurities in benzoguanamine;

[0032] A screw conveyor with a stirring paddle is provided at the bottom of the rotary disc extraction tower, and the screw conveyor is used to convey the extracted and washed benzoguanamine solid; the stirring paddle rotates with the screw to stir the solid at the bottom of the tower, so that the solid at the bottom of the tower is discharged evenly, and the solid is prevented from sticking to the tower wall and affecting the discharge.

[0033] On the basis of the above technical solution, preferably, the screw conveyor of the present invention is equipped with a stirring paddle before the starting end of the screw, and the stirring paddle rotates with the screw to stir the solids at the bottom of the tower, so that the solids at the bottom of the tower are discharged evenly and the stickiness of the solids on the tower wall is avoided to affect the discharge.

[0034] On the basis of the above technical solution, preferably, the screw conveyor can adjust the rotation frequency to change the discharge quality, so that the solid-liquid two-phase interface in the rotary disc extraction tower is maintained at the lower part of the rotary disc extraction tower.

[0035] The method and system for extracting and washing benzoguanamine provided by the present invention have the following beneficial effects compared with the prior art:

[0036] (1) The present invention prepares a slurry of the crude benzoguanamine product, continuously feeds the slurry by pumping, and continuously discharges the washed solids by a screw conveyor, thereby achieving continuous washing of the solid product and improving the washing efficiency; at the same time, the washed object is contacted with the washing water in advance, effectively increasing the contact time and thus improving the washing effect.

[0037] (2) The screw conveyor used in the present invention has a stirring paddle installed before the starting end of the screw, which can prevent the solid from sticking to the tower wall and affecting the continuity of the discharge.

[0038] (3) The present invention adopts a continuous washing method, which not only solves the problem of continuous feeding and discharging of the solid washing of the crude benzoguanamine product, but also realizes the extraction and washing of impurities such as benzamide and potassium hydroxide in the crude benzoguanamine product. At the same time, it also solves the problem of huge consumption of washing water caused by multiple washings required in traditional intermittent cross-current washing, thus saving washing water. The mechanized feeding and discharging method also reduces manual operations and saves manpower and material resources.

[0039] (4) The method for washing benzoguanamine of the present invention adopts a rotary disc extraction tower for countercurrent washing. The benzoguanamine solid contacts with the washing water in the tower in countercurrent. Under the stirring of the fixed rotary disc, the washing liquid and the washed material can be fully dispersed and contacted, which can effectively increase the mass transfer area, efficiently remove impurities such as benzamide and potassium hydroxide remaining in the benzoguanamine, reduce the ash content and free alkali content of the product, and improve the purity of the benzoguanamine product.

[0040] (5) The height of the rotary disc extraction tower used in the present invention can be reasonably increased according to actual application to obtain a better washing effect, thereby improving product purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A process flow chart of the extraction and washing of benzoguanamine provided by the present invention;

[0043] In the figure, 1 is a homogenizing device; 2 is a feed flow controller; 3 is a feed pump; 4 is a rotary disc extraction tower; and 5 is a screw conveyor. DETAILED DESCRIPTION

[0044] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The present invention is further described below in conjunction with specific embodiments, and the protection scope of the present invention is not limited by the following embodiments. The sources of materials and equipment mainly involved in the embodiments are all conventional commercial products.

[0046] In the following examples, the selected raw material benzoguanamine crude product solid was sampled and tested, and the total content of benzamide, ash and free alkali was 0.45%.

[0047] Example 1

[0048] This embodiment provides a method for continuous extraction and washing of a crude benzoguanamine product, which specifically comprises the following steps:

[0049] Step 1: Slurry preparation

[0050] The crude solid product of benzoguanamine (average particle size > 1 mm) is crushed into particles < 1 mm by a pulverizer and continuously added to a homogenizer through a solid feed port. At the same time, pure water 3 times the mass of the solid is injected into the homogenizer. The agitator of the homogenizer is started and the speed is set to 100 r / min to fully mix the solid and the pure water. The crude solid product of benzoguanamine is made into a slurry with good fluidity. The mixed slurry is used as a heavy phase feed for extraction and washing in a rotary disc extraction tower in the next step.

[0051] Step 2: Continuous extraction and washing

[0052] Pure water for washing as a continuous phase is continuously injected from the light phase inlet at the bottom of the rotary disc extraction tower at a flow rate of 5000 kg / h. After the extraction tower is filled with pure water, the slurry prepared by mixing the crude benzoguanamine product and pure water in the previous step is continuously injected into the rotary disc extraction tower from the heavy phase inlet at the top of the rotary disc extraction tower at a flow rate of 500 kg / h. The heavy phase continuously settles downward, and the light phase continuously rises. After the light phase and the heavy phase are fully in countercurrent contact, the mixture is stirred by a fixed rotary disc in the rotary disc extraction tower under the drive of an axial motor with a rotation speed of 200 r / min, and is fully dispersed, mixed and washed, and benzamide and potassium hydroxide in the crude benzoguanamine product are dissolved by pure water.

[0053] Step 3: Discharging

[0054] After extraction and washing, the benzoguanamine solid naturally settles to the bottom of the rotary disc extraction tower. The screw conveyor at the bottom of the tower is started, and the spiral rotation frequency is adjusted to make the solid-liquid interface in the rotary disc extraction tower at the lower part of the tower. By maintaining this rotation frequency, the solid at the bottom of the tower is continuously discharged; the washing water containing impurities such as benzamide and potassium hydroxide dissolved from the solid is discharged from the top of the rotary disc extraction tower as the light phase.

[0055] The sample of the material discharged from the screw conveyor outlet was dehydrated and tested, and the total content of benzamide, ash and free alkali in the washed benzoguanamine was 0.01%. The total content of benzamide, ash and free alkali in the washed benzoguanamine was reduced from 0.45% to 0.01%, and the impurity removal rate was 97.8%.

[0056] Example 2

[0057] This embodiment provides a method for continuous extraction and washing of a crude benzoguanamine product, which specifically comprises the following steps:

[0058] Step 1: Slurry preparation

[0059] The crude solid product of benzoguanamine (average particle size > 1 mm) is crushed into particles < 1 mm by a pulverizer and continuously added to a homogenizing device through a solid feed port. At the same time, pure water twice the mass of the solid is injected into the homogenizing device. The agitator of the homogenizing device is started and the speed is set to 200 r / min to fully mix the solid and the pure water. The crude solid product of benzoguanamine is made into a slurry with good fluidity. The mixed slurry is used as a heavy phase feed for extraction and washing in a rotary disc extraction tower in the next step.

[0060] Step 2: Continuous extraction and washing

[0061] Pure water for washing as a continuous phase is continuously injected from the light phase inlet at the bottom of the rotary disc extraction tower at a flow rate of 4000 kg / h. After the extraction tower is filled with pure water, the slurry prepared by mixing the crude benzoguanamine product and pure water in the previous step is continuously injected into the rotary disc extraction tower from the heavy phase inlet at the top of the rotary disc extraction tower at a flow rate of 500 kg / h. The heavy phase continuously settles downward, and the light phase continuously rises. After the light phase and the heavy phase are fully contacted in countercurrent, the mixture is stirred by a fixed rotary disc in the rotary disc extraction tower under the drive of an axial motor with a rotation speed of 300 r / min, and is fully dispersed, mixed and washed, and benzamide and potassium hydroxide in the crude benzoguanamine product are dissolved by pure water.

[0062] Step 3: Discharging

[0063] After extraction and washing, the benzoguanamine solid naturally settles to the bottom of the rotary disc extraction tower. The screw conveyor at the bottom of the tower is started, and the spiral rotation frequency is adjusted to make the solid-liquid interface in the rotary disc extraction tower at the lower part of the tower. By maintaining this rotation frequency, the solid at the bottom of the tower is continuously discharged; the washing water containing impurities such as benzamide and potassium hydroxide dissolved from the solid is discharged from the top of the rotary disc extraction tower as the light phase.

[0064] The sample of the material discharged from the screw conveyor outlet was dehydrated and tested, and the total content of benzamide, ash and free alkali in the washed benzoguanamine was 0.02%. The total content of benzamide, ash and free alkali in the washed benzoguanamine was reduced from 0.45% to 0.02%, and the impurity removal rate was 95.6%.

[0065] Example 3

[0066] This embodiment provides a method for continuous extraction and washing of a crude benzoguanamine product, which specifically comprises the following steps:

[0067] Step 1: Slurry preparation

[0068] The crude solid product of benzoguanamine (average particle size > 1 mm) is crushed into particles < 1 mm by a pulverizer and continuously added to a homogenizing device through a solid feed port. At the same time, pure water twice the mass of the solid is injected into the homogenizing device. The agitator of the homogenizing device is started and the speed is set to 300 r / min to fully mix the solid and the pure water. The crude solid product of benzoguanamine is made into a slurry with good fluidity. The mixed slurry is used as a heavy phase feed for extraction and washing in a rotary disc extraction tower in the next step.

[0069] Step 2: Continuous extraction and washing

[0070] The pure water for washing as the continuous phase is continuously injected from the light phase inlet at the bottom of the rotary disc extraction tower at a flow rate of 3000 kg / h. After the extraction tower is filled with the pure water, the slurry prepared by mixing the crude benzoguanamine product and the pure water in the previous step is continuously injected into the rotary disc extraction tower from the heavy phase inlet at the top of the rotary disc extraction tower at a flow rate of 400 kg / h. The heavy phase continuously settles downward, and the light phase continuously rises. After the light phase and the heavy phase are fully contacted in countercurrent, the mixture is stirred by the fixed rotary disc in the rotary disc extraction tower under the drive of the axial motor with a rotation speed of 300 r / min, and is fully dispersed, mixed and washed, and the benzamide and potassium hydroxide in the crude benzoguanamine product are dissolved by the pure water.

[0071] Step 3: Discharging

[0072] After extraction and washing, the benzoguanamine solid naturally settles to the bottom of the rotary disc extraction tower. The screw conveyor at the bottom of the tower is started, and the spiral rotation frequency is adjusted to make the solid-liquid interface in the rotary disc extraction tower at the lower part of the tower. By maintaining this rotation frequency, the solid at the bottom of the tower is continuously discharged; the washing water containing impurities such as benzamide and potassium hydroxide dissolved from the solid is discharged from the top of the rotary disc extraction tower as the light phase.

[0073] The sample of the material discharged from the screw conveyor outlet was dehydrated and tested, and the total content of benzamide, ash and free alkali in the washed benzoguanamine was 0.01%. The total content of benzamide, ash and free alkali in the washed benzoguanamine was reduced from 0.45% to 0.01%, and the impurity removal rate was 97.8%.

[0074] Example 4

[0075] This embodiment provides a method for continuous extraction and washing of a crude benzoguanamine product, which specifically comprises the following steps:

[0076] Step 1: Slurry preparation

[0077] The crude solid product of benzoguanamine (average particle size > 1 mm) is crushed into particles < 1 mm by a pulverizer and continuously added to a homogenizing device through a solid feed port. At the same time, pure water of 1 times the mass of the solid is injected into the homogenizing device. The agitator of the homogenizing device is started and the speed is set to 300 r / min to fully mix the solid and the pure water. The crude solid product of benzoguanamine is made into a slurry with good fluidity. The mixed slurry is used as the heavy phase feed for extraction and washing in a rotary disc extraction tower in the next step.

[0078] Step 2: Continuous extraction and washing

[0079] The pure water for washing as the continuous phase is continuously injected from the light phase inlet at the bottom of the rotary disc extraction tower at a flow rate of 5000 kg / h. After the extraction tower is filled with the pure water, the slurry prepared by mixing the crude benzoguanamine product and the pure water in the previous step is continuously injected into the rotary disc extraction tower from the heavy phase inlet at the top of the rotary disc extraction tower at a flow rate of 500 kg / h. The heavy phase continuously settles downward, and the light phase continuously rises. After the light phase and the heavy phase are fully contacted in countercurrent, the mixture is stirred by the fixed rotary disc in the rotary disc extraction tower under the drive of the axial motor with a rotation speed of 300 r / min, and is fully dispersed, mixed and washed, and the benzamide and potassium hydroxide in the crude benzoguanamine product are dissolved by the pure water.

[0080] Step 3: Discharging

[0081] After extraction and washing, the benzoguanamine solid naturally settles to the bottom of the rotary disc extraction tower. The screw conveyor at the bottom of the tower is started, and the spiral rotation frequency is adjusted to make the solid-liquid interface in the rotary disc extraction tower at the lower part of the tower. By maintaining this rotation frequency, the solid at the bottom of the tower is continuously discharged; the washing water containing impurities such as benzamide and potassium hydroxide dissolved from the solid is discharged from the top of the rotary disc extraction tower as the light phase.

[0082] The sample of the material discharged from the screw conveyor outlet was dehydrated and tested, and the total content of benzamide, ash and free alkali in the washed benzoguanamine was 0.01%. The total content of benzamide, ash and free alkali in the washed benzoguanamine was reduced from 0.45% to 0.01%, and the impurity removal rate was 97.8%.

[0083] Example 5

[0084] This embodiment provides a system for implementing a method for continuous extraction and washing of crude benzoguanamine products, the system comprising a homogenizing device, a feed flow controller, a feed pump, a rotary disc extraction tower, and a screw conveyor connected in sequence; specifically:

[0085] Step 1: Slurry preparation

[0086] The crude solid product of benzoguanamine (average particle size > 1 mm) is crushed into particles < 1 mm by a pulverizer and continuously added to a homogenizer through a solid feed port. At the same time, pure water 3 times the mass of the solid is injected into the homogenizer. The agitator of the homogenizer is started at a speed of 300 r / min to fully mix the solid and the pure water. The crude solid product of benzoguanamine is made into a slurry with good fluidity. The mixed slurry is used as a heavy phase feed for extraction and washing in a rotary disc extraction tower in the next step.

[0087] In this embodiment, by crushing the coarse product solid into particles less than 1 mm in size, the contact area between the solid and the washing liquid is increased, making it easier for the internal impurities to be penetrated and dissolved by the washing liquid, thereby improving the thoroughness and efficiency of washing.

[0088] In this embodiment, by continuously adding the crushed solid and pure water, a slurry with good fluidity is formed, thereby ensuring the continuity and stability of the production process and avoiding production interruptions caused by material agglomeration or poor fluidity.

[0089] In this embodiment, by precisely controlling the mass ratio of solid to pure water (1:3) and the rotation speed of the agitator (300 r / min), it is ensured that the solid and pure water are fully mixed to form a uniform slurry, providing good initial conditions for subsequent extraction and washing.

[0090] Step 2: Continuous extraction and washing

[0091] A feed flow controller is used to continuously inject pure water for washing as a continuous phase from the light phase inlet at the bottom of the rotary disc extraction tower through a feed pump at a flow rate of 7000 kg / h. After the extraction tower is filled with pure water, a slurry prepared by mixing the crude benzoguanamine product and pure water in the previous step is continuously injected into the rotary disc extraction tower from the heavy phase inlet at the top of the rotary disc extraction tower through a feed pump at a flow rate of 1000 kg / h. The heavy phase continuously settles downward, and the light phase continuously rises. After the light phase and the heavy phase are fully in contact, the mixture is stirred by a fixed rotary disc in the rotary disc extraction tower driven by an axial motor with a rotation speed of 100 r / min, and is fully dispersed, mixed and washed, and benzamide and potassium hydroxide in the crude benzoguanamine product are dissolved by pure water.

[0092] In this embodiment, pure water is injected from the bottom as a continuous phase to ensure full contact between pure water and benzoguanamine slurry. The continuous flow of pure water not only removes dissolved impurities, but also continuously renews the contact surface, thereby improving the washing efficiency and washing effect.

[0093] In this embodiment, the design of the disc extraction tower allows the continuous injection and outflow of pure water and slurry, realizing continuous production. This not only improves production efficiency, but also reduces batch differences caused by intermittent operation, ensuring the stability of product quality.

[0094] In this embodiment, the fixed turntable in the turntable extraction tower rotates at high speed driven by an axial motor, generating strong stirring and shearing forces, so that the light phase and the heavy phase are fully mixed in the tower, enhancing the mass transfer effect between the two phases, and further improving the uniformity and thoroughness of washing.

[0095] In this embodiment, by precisely controlling the flow of pure water and slurry, the residence time and contact area of ​​the materials in the tower can be effectively managed to ensure that each particle can be fully washed. At the same time, flow control also helps to maintain stable operating conditions in the tower and avoid unstable washing effects caused by flow fluctuations.

[0096] In this embodiment, compared with the traditional washing kettle, the rotary disc extraction tower reduces the required washing time and energy consumption and reduces the production cost through the efficient mass transfer and heat transfer process. At the same time, the continuous production mode also reduces the idle time and maintenance cost of the equipment.

[0097] Step 3: Discharging

[0098] After extraction and washing, the benzoguanamine solid naturally settles to the bottom of the rotary disc extraction tower. The screw conveyor at the bottom of the tower is started, and the spiral rotation frequency is adjusted to make the solid-liquid interface in the rotary disc extraction tower at the lower part of the tower. By maintaining this rotation frequency, the solid at the bottom of the tower is continuously discharged; the washing water containing impurities such as benzamide and potassium hydroxide dissolved from the solid is discharged from the top of the rotary disc extraction tower as the light phase.

[0099] In this embodiment, the high-speed operation of the agitator makes the solid particles evenly dispersed to avoid agglomeration, ensures good fluidity of the material at the bottom of the tower, facilitates subsequent discharging operations, and avoids blockage and production interruption.

[0100] In this embodiment, the solid and the washing water can be effectively separated by the design of the rotary disc extraction tower. The solid settles to the bottom of the tower, while the washing water containing impurities is discharged from the top of the tower as a light phase, ensuring that the impurities in the washing water will not be re-mixed into the solid, thereby improving the purity of the product.

[0101] In this embodiment, the discharge quality is changed by adjusting the rotation frequency of the screw conveyor to maintain the solid-liquid interface in the rotary disc extraction tower at the lower part of the rotary disc extraction tower, thereby obtaining a better washing effect and solid-liquid separation degree.

[0102] In this embodiment, the stirring paddle at the starting end of the spiral rotates with the spiral, which can stir the solids at the bottom of the tower, prevent the solids from sticking to the tower wall, ensure uniform discharge of the solids at the bottom of the tower, ensure the stability and continuity of the washing process, avoid production instability due to flow fluctuations, and improve production efficiency and product quality.

[0103] In this embodiment, the discharge of the heavy phase discharge port of the rotary disc extraction tower is sampled through the sampling port set at the bottom of the tower. After dehydration to a moisture content of <0.1%, the ash content and free alkali content are detected with reference to the method of the enterprise standard "Q / WYJ 020-2023 Benzocyanamide" of Wuhan Organic Industrial Co., Ltd. The test result is that the ash content is not detected and the free alkali content is 0.01%, and the benzamide content is detected with reference to the general method of gas chromatography, and the result is that it is not detected. This result shows that the total content of ash and free alkali in the benzocyanamide solid after washing is 0.01%, which is significantly better than the requirements of ash content ≤0.1% and free alkali content ≤0.05% in the standard, and does not contain benzamide impurities. After washing, the total content of benzamide, ash and free alkali in benzocyanamide is reduced from 0.45% to 0.01%, and the impurity removal rate reaches 97.8%.

[0104] Comparative Example

[0105] The same batch of crude benzoguanamine products was subjected to the conventional intermittent flushing and washing process. 50 kg of crude benzoguanamine solids were placed in a washing kettle, and 350 kg of hot water was added. The solids were stirred and washed to disperse the solids in the water. After stirring for 2 hours, the stirring was stopped, the water layer was pumped out, and the solids were filtered out and sent to a drying oven to dry the water. After drying to a moisture content of less than 0.1%, the ash content and free alkali content were detected according to the method of Wuhan Organic Industrial Co., Ltd.'s enterprise standard "Q / WYJ 020-2023 Benzocyanamide", and the benzamide content was detected according to the general method of gas chromatography. The test results showed that the ignition residue content was 0.15%, the free alkali content was 0.12%, and the benzamide content was 0.13%. This result shows that the total ash and free alkali content in the benzocyanate melamine solid after one water washing using the traditional intermittent flushing washing process does not meet the requirements of the "Q / WYJ 020-2023 Benzocyanate" standard of ash content ≤0.1% and free alkali content ≤0.05%, and contains 0.13% benzamide impurities, and the product purity is not high enough.

[0106] The benzoguanamine solid after one water washing using a traditional intermittent flushing washing process was washed multiple times continuously until it was washed 7 times, and the solid moisture was filtered out and dried. The benzoguanamine solid ash content was 0.08%, the free alkali content was 0.04%, and the benzamide content was 0.05%, which met the requirements of the "Q / WYJ 020-2023 Benzoguanamine" standard of ash content ≤0.1% and free alkali content ≤0.05%, but still contained 0.05% of benzamide impurities, and the product purity was not pure enough.

[0107] The total content of benzamide, ash and free alkali in the benzoguanamine solid after four water washings using the conventional intermittent flushing washing process was reduced from 0.45% to 0.17%, and the impurity removal rate was 62.2%.

[0108] In summary, the continuous water washing method using a rotating disc extraction tower in the present invention performs better in removing impurities and can achieve a higher impurity removal rate, thereby obtaining a purer product.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for continuous extraction and washing of crude benzoguanamine product, characterized in that: The method comprises the following steps: Step 1: Slurry preparation The solid crude product of benzoguanamine is crushed, mixed with water in a homogenizing device, and stirred to form a slurry; Step 2: Continuous extraction and washing Pure water is continuously injected from the light phase inlet of the rotary disc extraction tower as the light phase; the slurry of step 1 is continuously injected from the heavy phase inlet of the rotary disc extraction tower as the heavy phase; the heavy phase continuously settles downward, the light phase continuously rises, and after the light phase and the heavy phase are in countercurrent contact, the mixture is continuously stirred in the rotary disc extraction tower for extraction and washing, and the solid settles to the lower part of the rotary disc extraction tower to obtain the washed benzoguanamine solid; Step 3: Discharging The benzoguanamine solid in step 2 is continuously conveyed out by a screw conveyor, and the solid is dried and dehydrated after being discharged to obtain a benzoguanamine product.

2. The method according to claim 1, characterized in that In step 1, the particle size of the crushed benzoguanamine is less than 1 mm.

3. The method according to claim 2, characterized in that In step 1, the mass ratio of the benzoguanamine to the water is 1:1-3.

4. The method according to claim 3, characterized in that In step 1, the stirring speed is 50 to 500 r / min.

5. The method according to claim 1, characterized in that In step 2, the feed flow rate of the slurry is 50 to 5000 kg / h.

6. The method according to claim 5, characterized in that In step 2, the feed flow rate of the pure water is 1 to 10 times the flow rate of the slurry.

7. The method according to claim 6, characterized in that In step 2, the stirring speed is 50-500 r / min.

8. The method according to claim 1, characterized in that In step 3, the use of a screw conveyor to continuously convey the solid benzoguanamine from step 2 comprises: The solid discharge mass of benzoguanamine is changed by adjusting the rotation frequency of the screw conveyor, so that the solid-liquid two-phase interface in the rotary disc extraction tower is maintained at the lower part of the rotary disc extraction tower.

9. A benzoguanamine, characterized in that: The benzoguanamine is prepared by the method according to any one of claims 1 to 8. In the benzoguanamine, the total content of ash and free alkali formed by benzamide and impurities does not exceed 0.01%, and the impurity removal rate is not less than 95%.

10. A system for implementing the method according to any one of claims 1 to 8, characterized in that: The system comprises a homogenizing device, a feed flow controller, a feed pump, a rotary disc extraction tower, and a screw conveyor which are connected in sequence; The homogenizing device is used to prepare slurry; The feed flow controller is used to control the slurry feed flow rate; A feed pump is provided between the feed flow controller and the rotary disc extraction tower, and the feed pump is used to continuously convey the slurry produced by the homogenization device; The rotary disc extraction tower is used for countercurrent contact between the pure water and the slurry to achieve extraction and washing of impurities in benzoguanamine; A screw conveyor with a stirring paddle is provided at the bottom of the rotary disc extraction tower, and the screw conveyor is used to convey the extracted and washed benzoguanamine solid; the stirring paddle rotates with the screw to stir the solid at the bottom of the tower, so that the solid at the bottom of the tower is discharged evenly, and the solid is prevented from sticking to the tower wall and affecting the discharge.

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