Continuous preparation process of polyaluminum chloride water purifying agent

Abstract

The invention discloses a continuous preparation process of a polyaluminum chloride water purifying agent, and belongs to the technical field of preparation of water purifying agents. The continuous preparation process of the polyaluminum chloride water purifying agent comprises the following steps: step 1, grinding secondary aluminum ash in a mortar, and sieving to obtain pretreated secondary aluminum ash; 2, the pretreated secondary aluminum ash is washed, filtered and dried, and washed secondary aluminum ash is obtained; and 3, adding the modified catalyst into the washed secondary aluminum ash, adding distilled water, stirring, sealing a reaction kettle, heating, stirring and reacting in a nitrogen environment, filtering after the reaction is finished to obtain filtrate, transferring the filtrate into a reactor, adding a saturated sodium carbonate solution, and curing to obtain the polyaluminum chloride water purifying agent. The polyaluminum chloride water purifying agent prepared by the method has high purity and low impurity content.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water purifying agent preparation, and particularly relates to a continuous preparation process of polyaluminum chloride water purifying agent. BACKGROUND

[0002] As a high-efficiency inorganic polymer flocculant, polyaluminum chloride has become the core agent in the fields of drinking water purification, industrial wastewater treatment and water reuse due to its advantages such as strong adaptability, fast flocculation speed and low effluent turbidity. Traditional preparation processes mostly adopt batch processes. For example, although the aluminum acid dissolution method has low equipment investment, it has problems such as high impurity content, unstable product quality and serious equipment corrosion. The aluminum hydroxide pressurized acid dissolution method can improve the purity, but it needs to rely on a high-pressure reactor, and the energy consumption and equipment maintenance cost are significantly increased. The aluminum-containing mineral roasting acid leaching method realizes resource comprehensive utilization, but is affected by mineral composition fluctuation, has great difficulty in controlling the basicity, and the batch operation leads to low production efficiency. In addition, the existing processes have shortcomings in continuous control, such as difficulty in real-time optimization of parameters such as temperature, pressure and reaction time, which leads to poor consistency of product performance and makes it difficult to meet the strict requirements of large-scale water treatment projects on the stability of the agent. Therefore, developing a continuous preparation process integrating raw material pretreatment, continuous polymerization reaction, intelligent parameter regulation and efficient separation and drying has become a key direction to break through the industry bottleneck and improve the product quality and production efficiency of polyaluminum chloride.

[0003] Patent CN114195176B discloses a preparation process of polyaluminum chloride water purifying agent, which comprises the following steps: adding aluminum hydroxide powder into sodium hydroxide solution, and obtaining sodium aluminate solution after heating; cooling the sodium aluminate solution and adding hydrochloric acid for neutralization, and adding hydrochloric acid while passing carbon dioxide, to obtain a mixed solution containing aluminum hydroxide and polyaluminum chloride; adjusting the basicity by adding hydrochloric acid after filtering the mixed solution, and obtaining polyaluminum chloride water purifying agent after heating and aging. The polyaluminum chloride prepared by the method has the advantages of low impurity content, high purity and good water purification effect. However, in the process of neutralizing the sodium aluminate solution with hydrochloric acid after cooling, the operation of adding hydrochloric acid while passing carbon dioxide has extremely strict requirements on the control of reaction conditions. The amount of carbon dioxide passed and the speed of hydrochloric acid addition are difficult to accurately match, which easily leads to uneven local reaction environment, making the ratio of generated aluminum hydroxide and polyaluminum chloride unstable, and further affecting the consistency of the basicity of the final product. Moreover, due to the lack of effective dynamic monitoring and regulation mechanism, there are differences in the molecular structure polymerization degree of different batches of products after the subsequent heating and aging of the basicity adjustment, which to some extent limits the universality and stability of the water purifying agent under different water quality conditions. SUMMARY

[0004] The present application aims to provide a continuous preparation process of polyaluminum chloride water purifying agent, which is used to solve the technical problems of long preparation time and poor product quality of polyaluminum chloride water purifying agent in the prior art.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions: The present application provides a continuous preparation process of polyaluminum chloride water purifying agent, which comprises the following steps: Step one: put the secondary aluminum ash into a mortar for grinding, and sieve to obtain pretreated secondary aluminum ash; Step two: wash, filter and dry the pretreated secondary aluminum ash to obtain washed secondary aluminum ash; Step three: add a modified catalyst to the washed secondary aluminum ash, add distilled water for stirring, seal a reaction kettle, and heat and stir under a nitrogen environment for reaction; after the reaction is completed, filter to obtain a filtrate, transfer the filtrate to a reactor, add a saturated sodium carbonate solution, and mature to obtain a polyaluminum chloride water purifying agent.

[0006] Preferably, in the step one, the sieving particle size is 250-320 μm.

[0007] Preferably, in the step two, the washing process is: Q1: divide the pretreated secondary aluminum ash into three parts, respectively, and put them into first, second and third reaction kettles; add deionized water to the third reaction kettle, heat and stir for reaction; after the reaction is completed, separate the solid and liquid, pump the obtained third washing liquid to the second reaction kettle, at the same time, add deionized water to the second reaction kettle, continue to heat and stir for reaction, and after the solid and liquid are separated, pump the obtained second washing liquid to the first reaction kettle, at the same time, add deionized water to the first reaction kettle, heat and stir for reaction, and after the solid and liquid are separated, obtain a first washing liquid and send it to a wastewater collection tank for collection; Q2: add deionized water to the third reaction kettle for washing, and after the solid and liquid are separated, continue to pump the washing liquid to the second reaction kettle for washing, then continue to pump the washing liquid to the first reaction kettle, and then send the washed washing liquid to the wastewater collection tank for collection, repeat the operation, and at the same time, recycle the wastewater in the wastewater collection tank.

[0008] In the above process, by allowing the washing water and the washed material to be transmitted in the opposite direction, the dirtiest material (first aluminum ash) encounters the dirtiest washing liquid (the impurity concentration of which is still lower than that in the aluminum ash), and the cleanest material (third aluminum ash) encounters the cleanest fresh deionized water, and in each stage, the maximum concentration difference is maintained, and the highest washing efficiency is achieved with the least water.

[0009] As preferred, in the Q1, after adding deionized water into the third stage reactor, the liquid-solid ratio is (8-13):(1-1.2), the heating and stirring reaction temperature is 85-95℃, and the reaction time is 1-5h; in the Q2, the washing is ended when the ammonia nitrogen concentration in the washing liquid tends to be stable and no longer increases significantly.

[0010] As preferred, in the Q2, in the recovery process, the wastewater is first filtered to remove suspended particles, collected in the adjusting tank, and then pumped into the clean water tank of the stripping tower, sodium hydroxide is added, stirred vigorously, the pH is adjusted to 10.5-11.5, then uniformly sprayed into the packed tower, while steam is blown from the bottom of the tower, the treated wastewater is discharged from the bottom of the tower and collected for washing in the first stage reactor, and the discharged gas enters the absorption tower, is sprayed with clean water at the top of the tower, and the byproduct is collected for self-use.

[0011] As preferred, in the step three, the preparation method of the modified catalyst comprises the following steps: S1: dichloroethane, benzene and benzylamine are sequentially added to a container, stirred in an ice bath, then dimethoxymethane and anhydrous ferric chloride are added, stirred at room temperature under nitrogen atmosphere, then the temperature is increased for stirring reaction, and then the temperature is further increased for stirring reaction, after the reaction is completed, cooling, washing, filtration, Soxhlet extraction, alkalization, washing, filtration, vacuum drying, and a brown powder is obtained; S2: the brown powder is added to a container containing dichloroethane, swelled, then a dichloromethane solution containing chlorosulfonic acid is slowly added dropwise under ice-salt bath conditions, heated and stirred under nitrogen atmosphere, after the reaction is completed, cooling, pouring into ice water to quench the reaction, washing, filtration, extraction, and vacuum drying to obtain a modified catalyst.

[0012] In the above process, benzene and benzylamine are used as raw materials, Friedel-Crafts alkylation reaction is used to cross-link the super-cross-linked polymer (brown powder), and then sulfonation treatment is performed to introduce acidic groups to prepare the modified catalyst.

[0013] As preferred, in the S1, the amount ratio of dichloroethane, benzene, benzylamine, dimethoxymethane and anhydrous ferric chloride is (50-75)mL:(1.664-1.882)mL:(0.683-0.924)mL:(6.08-6.24)mL:(11.15-12.03)g, the ice bath stirring time is 30-45min, the room temperature stirring reaction time is 30-45min, the temperature is increased to 40-50℃ for stirring reaction for 5-7h, the temperature is further increased to 80-84℃ for stirring reaction for 15-20h, the temperature is cooled to 28-30℃, washed with methanol, alkalized with 10wt% sodium bicarbonate solution for 20-24h, and washed with distilled water.

[0014] As preferred, in the step S2, the use amount ratio of the brown powder, dichloroethane, chlorosulfonic acid and dichloromethane is (0.5-0.7) g:(15-19) mL:(0.25-0.32) mL:(10-12) mL, the swelling time is 2-4 h, and the stirring reaction is carried out at 45-50 DEG C for 4-6 h.

[0015] As preferred, in the step three, the use amount ratio of the modified catalyst, the washed secondary aluminum ash and distilled water is (1-1.2) g:(5-8) g:(30-48) mL, the stirring reaction temperature is 105-120 DEG C, the pressure is 0.2-0.5 MPa, the time is 2-4 h, the reactor is the first stage in the three-stage series stirred tank reactor, the saturated sodium carbonate solution is added into the first stage reactor, the pH is controlled to be 3-3.5, the temperature is 85-90 DEG C, then overflowed into the second stage reactor, the saturated sodium carbonate solution is continuously added, the pH is controlled to be 4-4.3, the temperature is 90-95 DEG C, the time is 1-2 h, finally into the third stage reactor, the saturated sodium carbonate solution is stopped, the temperature is 88-90 DEG C, and the aging time is 2-3 h.

[0016] In summary, due to the adoption of the above technical scheme, the present application has the following beneficial effects: 1. The present application realizes the continuous production of polyaluminum chloride by integrating the grinding of secondary aluminum ash, multi-stage countercurrent washing, catalytic acid dissolution and multi-stage series aging process, greatly improves the production efficiency, at the same time, the countercurrent washing process significantly reduces the water consumption, the washing wastewater can be recycled for primary washing after blow-off recovery treatment, realizes the recycling of water resources and the recovery of ammonia-nitrogen by-products, reduces the wastewater treatment cost, and the overall process has excellent environmental protection.

[0017] 2. In the countercurrent washing process, the maximum concentration difference is maintained to efficiently remove the soluble impurities in the aluminum ash with the least amount of water, providing high-purity raw materials for the subsequent reaction, the washed aluminum ash and the modified catalyst are efficiently reacted in the pressurized reactor, the dissolved filtrate then enters the multi-stage series reactor for progressive neutralization and aging, by accurately controlling the pH and temperature of each stage, the aluminum hydrolysis polymerization is promoted to form stable polyaluminum chloride products, effectively avoiding the precipitation caused by local over-alkaline, and the product quality is stable and the effective ingredient content is high.

[0018] 3. The prepared modified catalyst has abundant acid sites and stable porous structure, efficiently catalyzing the dissolution of aluminum in the acid dissolution process, the reaction conditions are milder, the reaction time is shortened, the aluminum dissolution rate is improved, at the same time, the catalyst is not easy to deactivate, can be separated and recycled, reduces the production cost, avoids the impurities possibly introduced by metal catalysts, and ensures the purity and safety performance of the water purifying agent. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The preparation process flow chart of the polyaluminum chloride water purifying agent of the present application is shown in the figure. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0021] Embodiment 1: The present embodiment discloses a preparation method of a modified catalyst, comprising the following steps: S1: 62.5 mL of dichloroethane, 1.743 mL of benzene and 0.853 mL of benzylamine are sequentially added into a container, stirred in an ice bath for 30 min, then 6.16 mL of dimethoxymethane and 11.53 g of anhydrous ferric chloride are added, stirred at room temperature for 45 min under nitrogen atmosphere, then heated to 45℃ and stirred for 6 h, then heated to 82℃ and stirred for 16 h, after the reaction is completed, cooled to 28℃, washed with methanol, filtered, Soxhlet extracted, alkalized with 10 wt% sodium bicarbonate solution for 24 h, washed with distilled water, filtered and vacuum dried to obtain a brown powder; S2: 0.6 g of the brown powder is added into a container containing 17 mL of dichloroethane, swelled for 4 h, then 11 mL of a dichloromethane solution containing 0.28 mL of chlorosulfonic acid is slowly added dropwise under ice-salt bath condition, heated to 45℃ and stirred for 6 h under nitrogen atmosphere, after the reaction is completed, cooled, poured into ice water to quench the reaction, washed, filtered, extracted and vacuum dried to obtain a modified catalyst.

[0022] Reference Figure 1 The present embodiment discloses a continuous preparation process of a polyaluminum chloride water purifying agent, and the process is characterized by comprising the following steps: Step one: the secondary aluminum ash is put into a mortar for grinding, and then passed through a 300 μm sieve to obtain pretreated secondary aluminum ash; Step two: the pretreated secondary aluminum ash is washed, filtered and dried to obtain washed secondary aluminum ash; The washing process is as follows: Q1: divide the pretreated secondary aluminum ash into three parts, and respectively pour into the first, second and third reaction kettles; add deionized water to the third reaction kettle, the liquid-solid ratio is 10.5:1.1, heat and stir at 90°C for 4h, after the reaction is completed, separate the solid and liquid, pump the obtained third washing liquid into the second reaction kettle, continue to heat and stir, separate the solid and liquid, pump the obtained second washing liquid into the first reaction kettle, heat and stir, separate the solid and liquid, obtain the first washing liquid, and collect in the wastewater collection tank; Q2: add deionized water to the third reaction kettle for washing, separate the solid and liquid, continue to pump the washing liquid into the second reaction kettle for washing, then continue to pump the washing liquid into the first reaction kettle, then collect the washed washing liquid in the wastewater collection tank, and repeat the operation until the ammonia nitrogen concentration in the washing liquid tends to be stable and no longer increases significantly, and the washing is completed, at the same time, the wastewater in the wastewater collection tank is recovered and treated, in the recovery and treatment process, first, the wastewater is filtered to remove suspended particles and collected in the adjusting tank, then pumped into the clean water tank of the stripping tower, sodium hydroxide is added, stirred vigorously, the pH is adjusted to 11, then uniformly sprayed into the packed tower, at the same time, steam is introduced from the bottom of the tower, the treated wastewater is discharged from the bottom of the tower, and the treated wastewater is collected and used for washing in the first reaction kettle, the discharged gas enters the absorption tower, and the gas is sprayed and absorbed at the top of the tower to obtain a byproduct, which is collected and used. Step three: add 1.1g of modified catalyst to 6.5g of water-washed secondary aluminum ash, add 39mL of distilled water, stir, seal the reaction kettle, heat and stir at 0.5MPa and 112°C for 4h under nitrogen environment, after the reaction is completed, filter to obtain a filtrate, transfer to the first reactor of the 3-stage series stirred tank reactor, add saturated sodium carbonate solution to the first reactor, control the pH to be 3 and the temperature to be 85°C, then overflow to the second reactor, continue to add saturated sodium carbonate solution, control the pH to be 4 and the temperature to be 90°C, the time is 2h, finally enter the third reactor, stop adding saturated sodium carbonate solution, the temperature is 88°C, and the aging time is 3h, to obtain polyaluminum chloride water purifying agent.

[0023] Example 2: The embodiment discloses a preparation method of a modified catalyst, comprising the following steps: S1: 50 mL of dichloroethane, 1.664 mL of benzene and 0.683 mL of benzylamine were sequentially added into a container, stirred in an ice bath for 30 min, then 6.08 mL of dimethoxymethane and 11.15 g of anhydrous ferric chloride were added, stirred at room temperature for 45 min under nitrogen atmosphere, then heated to 45°C and stirred for 6 h, then heated to 82°C and stirred for 16 h, after the reaction was completed, cooled to 28°C, washed with methanol, filtered, Soxhlet extracted, alkalized with 10 wt% sodium bicarbonate solution for 24 h, washed with distilled water, filtered and vacuum dried to obtain a brown powder; S2: 0.5 g of the brown powder was added into a container containing 19 mL of dichloroethane, swelled for 4 h, then 10 mL of a dichloromethane solution containing 0.32 mL of chlorosulfonic acid was slowly added dropwise under ice-salt bath conditions, heated to 45°C and stirred for 6 h under nitrogen atmosphere, after the reaction was completed, cooled, poured into ice water to quench the reaction, washed, filtered, extracted and vacuum dried to obtain a modified catalyst.

[0024] Referring to Figure 1 As shown in the figure, the embodiment discloses a continuous preparation process of a polyaluminum chloride water purifying agent, and has the characteristics that the process comprises the following steps: Step one: put the secondary aluminum ash into a mortar for grinding, pass through a 300 μm sieve, and obtain pretreated secondary aluminum ash; Step two: wash, filter and dry the pretreated secondary aluminum ash to obtain washed secondary aluminum ash; The washing process is as follows: Q1: divide the pretreated secondary aluminum ash into three parts, respectively, and put them into first, second and third reaction kettles, add deionized water to the third reaction kettle, the liquid-solid ratio is 8:1, heat and stir at 90°C for 4 h, after the reaction is completed, separate the solid and liquid, pump the obtained third washing liquid to the second reaction kettle, at the same time, add deionized water to the second reaction kettle, continue to heat and stir, after the solid and liquid are separated, pump the obtained second washing liquid to the first reaction kettle, at the same time, add deionized water to the first reaction kettle, after heating and stirring, separate the solid and liquid, obtain the first washing liquid, and send it to a wastewater collection tank for collection; Q2: The deionized water is added into the third stage reaction kettle for washing, and after the solid-liquid separation, the washing liquid is continuously pumped into the second stage reaction kettle for washing, and then the washing liquid is continuously pumped into the first stage reaction kettle, and then the washed washing liquid is sent into the waste water collecting tank for collection, and the operation is repeated until the ammonia nitrogen concentration in the washing liquid tends to be stable and no longer significantly increases, and the washing is ended, and meanwhile, the waste water in the waste water collecting tank is recovered and treated, in the recovery and treatment process, the waste water is first filtered to remove suspended particles and collected into the adjusting tank for standing, and then pumped into the clean water tank of the stripping tower, sodium hydroxide is added, and stirred vigorously to adjust the pH to 10.8, and then uniformly sprayed into the packed tower, while steam is blown from the bottom of the tower, and the treated waste water is discharged from the bottom of the tower for washing in the first stage reaction kettle, and the discharged gas enters the absorption tower, and is sprayed and absorbed at the top of the tower with clean water to obtain a by-product which is collected for self-use; Step three: 1.2g modified catalyst is added into 5g water washed secondary aluminum ash, 48mL distilled water is added for stirring, the reaction kettle is closed, heated and stirred at 0.48MPa and 116℃ for 3h, after the reaction is completed, filtration is performed to obtain a filtrate which is transferred into the first stage reactor of the third stage series stirred tank reactor, saturated sodium carbonate solution is added into the first stage reactor, the pH is controlled to be 3.4, and the temperature is 86℃, then overflowed into the second stage reactor, saturated sodium carbonate solution is continuously added, the pH is controlled to be 4.2, the temperature is 91℃, and the time is 2h, finally into the third stage reactor, the saturated sodium carbonate solution is stopped, the temperature is 90℃, and the aging time is 3h, to obtain polyaluminum chloride water purifying agent.

[0025] Embodiment 3: The embodiment discloses a preparation method of a modified catalyst, comprising the following steps: S1: 75mL of dichloroethane, 1.882mL of benzene and 0.924mL of benzylamine are sequentially added into a container, stirred in an ice bath for 30min, then 6.16mL of dimethoxymethane and 12.03g of anhydrous ferric chloride are added, stirred at room temperature for 45min under a nitrogen atmosphere, then heated to 45℃ for stirring for 6h, then heated to 82℃ for stirring for 16h, after the reaction is completed, cooled to 28℃, washed with methanol, filtered, Soxhlet extracted, alkalized with 10wt% sodium bicarbonate solution for 24h, washed with distilled water, filtered, and vacuum dried to obtain a brown powder; S2: 0.7g of the brown powder is added into a container containing 15mL of dichloroethane, swelled for 4h, then 12mL of dichloromethane solution containing 0.25mL of chlorosulfonic acid is slowly added dropwise under an ice-salt bath condition, heated to 45℃ for stirring for 6h under a nitrogen atmosphere, after the reaction is completed, cooled, poured into ice water to quench the reaction, washed, filtered, extracted, and vacuum dried to obtain a modified catalyst.

[0026] ReferenceFigure 1 The embodiment shown discloses a continuous preparation process of polyaluminum chloride water purifying agent, characterized in that it comprises the following steps: Step one: put the secondary aluminum ash into a mortar for grinding, pass through a 300 μm sieve, and obtain pretreated secondary aluminum ash; Step two: wash, filter, and dry the pretreated secondary aluminum ash, and obtain washed secondary aluminum ash; The washing process is as follows: Q1: divide the pretreated secondary aluminum ash into three equal parts, respectively, and put them into the first, second, and third reaction kettles, add deionized water to the third reaction kettle, the liquid-solid ratio is 13:1.2, heat and stir at 89℃ for 3.5 h, after the reaction is completed, separate the solid and the liquid, pump the obtained third-stage washing liquid into the second reaction kettle, at the same time, add deionized water to the second reaction kettle, continue to heat and stir, after the solid and the liquid are separated, pump the obtained second-stage washing liquid into the first reaction kettle, at the same time, add deionized water to the first reaction kettle, after heating and stirring, separate the solid and the liquid, obtain the first-stage washing liquid, and send it into a wastewater collection tank for collection; Q2: add deionized water to the third reaction kettle for washing, after the solid and the liquid are separated, continue to pump the washing liquid into the second reaction kettle for washing, then continue to pump the washing liquid into the first reaction kettle, and then send the washed washing liquid into the wastewater collection tank for collection, repeat the operation until the ammonia nitrogen concentration in the washing liquid tends to be stable and no longer significantly increases, and at the same time, the wastewater in the wastewater collection tank is recovered and treated, in the recovery and treatment process, first, filter the wastewater to remove suspended particles, collect them into an adjustment tank, and then pump them into a water purification tank of a stripping tower, add sodium hydroxide, stir vigorously, adjust the pH to 11.3, then uniformly spray them into a packed tower, at the same time, blow steam from the bottom of the tower, and the treated wastewater is discharged from the bottom of the tower, collected and used for washing in the first reaction kettle, and the discharged gas enters an absorption tower, at the top of the tower, is sprayed with clean water for absorption, and the byproduct is collected and used; Step three: add 1 g of modified catalyst to 8 g of washed secondary aluminum ash, add 30 mL of distilled water, stir, seal the reaction kettle, heat and stir at 0.28 MPa and 118℃ for 4 h under a nitrogen environment, after the reaction is completed, filter to obtain a filtrate, transfer the filtrate into the first reactor of a three-stage series stirred tank reactor, add saturated sodium carbonate solution to the first reactor, control the pH to 3.4 and the temperature to 89℃, then overflow to the second reactor, continue to add saturated sodium carbonate solution, control the pH to 4.1 and the temperature to 91℃, the time is 21.5 h, finally, enter the third reactor, stop adding saturated sodium carbonate solution, the temperature is 89℃, and the aging time is 2 h, to obtain the polyaluminum chloride water purifying agent.

[0027] Embodiment 4: The embodiment discloses a preparation method of a modified catalyst, and comprises the following steps: S1: 55 mL of dichloroethane, 1.687 mL of benzene and 0.721 mL of benzylamine are sequentially added into a container, stirred in an ice bath for 30 min, then 6.12 mL of dimethoxymethane and 11.27 g of anhydrous ferric chloride are added, stirred at room temperature for 45 min under a nitrogen atmosphere, then heated to 45 DEG C and stirred for 6 h, then heated to 82 DEG C and stirred for 16 h, after the reaction is completed, cooled to 28 DEG C, washed with methanol, filtered, Soxhlet extracted, alkalized with a 10 wt% sodium bicarbonate solution for 24 h, washed with distilled water, filtered and vacuum dried to obtain a brown powder; S2: 0.55 g of the brown powder is added into a container containing 16 mL of dichloroethane, swelled for 4 h, then 10.5 mL of a dichloromethane solution containing 0.26 mL of chlorosulfonic acid is slowly added dropwise under an ice-salt bath, heated to 45 DEG C and stirred for 6 h under a nitrogen atmosphere, after the reaction is completed, cooled, poured into ice water to quench the reaction, washed, filtered, extracted and vacuum dried to obtain a modified catalyst.

[0028] Reference Figure 1 The embodiment discloses a continuous preparation process of a polyaluminum chloride water purifying agent, and is characterized by comprising the following steps: Step one: the secondary aluminum ash is put into a mortar for grinding, and is filtered through a 300 mu m sieve to obtain pretreated secondary aluminum ash; Step two: the pretreated secondary aluminum ash is washed, filtered and dried to obtain washed secondary aluminum ash; The washing process is as follows: Q1: the pretreated secondary aluminum ash is evenly divided into three parts and is respectively put into first, second and third reaction kettles, deionized water is added into the third reaction kettle, the liquid-solid ratio is 9:1.15, heating and stirring are carried out at 92 DEG C for 3 h, after the reaction is completed, solid-liquid separation is carried out, the obtained third washing liquid is pumped into the second reaction kettle, deionized water is added into the second reaction kettle, heating and stirring are continuously carried out, after solid-liquid separation, the obtained second washing liquid is pumped into the first reaction kettle, deionized water is added into the first reaction kettle, after heating and stirring, solid-liquid separation is carried out, the first washing liquid is obtained and is collected in a waste water collecting tank; Q2: Deionized water is added to the third-stage reaction kettle for washing, and after solid-liquid separation, the washing liquid is continuously pumped into the second-stage reaction kettle for washing, and then the washing liquid is continuously pumped into the first-stage reaction kettle, and then the washed washing liquid is sent into the wastewater collection tank for collection. The operation is repeated until the ammonia nitrogen concentration in the washing liquid tends to be stable and no longer significantly increases, and the washing is ended. At the same time, the wastewater in the wastewater collection tank is recovered and treated. In the recovery and treatment process, the wastewater is first filtered to remove suspended particles and collected in the adjusting tank, and then pumped into the clean water tank of the stripping tower, and sodium hydroxide is added, and stirred vigorously to adjust the pH to 11.2, and then uniformly sprayed into the packed tower. At the same time, steam is blown from the bottom of the tower, and the treated wastewater is discharged from the bottom of the tower and collected for washing in the first-stage reaction kettle. The discharged gas enters the absorption tower, and water is sprayed at the top of the tower for absorption to obtain a byproduct, which is collected for self-use. Step three: 1.05g modified catalyst is added to 6g water-washed secondary aluminum ash, 32mL distilled water is added and stirred, the reaction kettle is closed, heated and stirred at 0.34MPa and 110℃ for 4h. After the reaction is completed, filtration is performed to obtain a filtrate, which is transferred to the first-stage reactor in the third-stage series stirred tank reactor. Saturated sodium carbonate solution is added to the first-stage reactor to control the pH to 3.3 and the temperature to 86℃. Then it overflows into the second-stage reactor, and saturated sodium carbonate solution is continuously added to control the pH to 4.2 and the temperature to 94℃ for 1h. Finally, it enters the third-stage reactor, and the addition of saturated sodium carbonate solution is stopped, and the temperature is 88℃ for 2h to obtain polyaluminum chloride water purifier.

[0029] Example 5: The present embodiment discloses a preparation method of a modified catalyst, comprising the following steps: S1: 60mL of dichloroethane, 1.783mL of benzene and 0.873mL of benzylamine are sequentially added to a container, and stirred in an ice bath for 30min. Then 6.21mL of dimethoxymethane and 11.93g of anhydrous iron chloride are added, and stirred at room temperature for 45min under nitrogen atmosphere. Then the temperature is increased to 45℃ and stirred for 6h, and then the temperature is further increased to 82℃ and stirred for 16h. After the reaction is completed, the temperature is cooled to 28℃, washed with methanol, filtered, Soxhlet extracted with 10wt% sodium bicarbonate solution for 24h, washed with distilled water, filtered and vacuum dried to obtain a brown powder; S2: 0.65g of the brown powder is added to a container containing 18mL of dichloroethane, and swelled for 4h. Then 11.5mL of dichloromethane solution containing 0.31mL of chlorosulfonic acid is slowly added dropwise under ice-salt bath condition, and heated to 45℃ and stirred for 6h under nitrogen atmosphere. After the reaction is completed, it is cooled, poured into ice water to quench the reaction, washed, filtered, extracted and vacuum dried to obtain a modified catalyst.

[0030] Reference Figure 1 The embodiment shown discloses a continuous preparation process of polyaluminum chloride water purifying agent, characterized in that it comprises the following steps: Step one: put the secondary aluminum ash into a mortar for grinding, pass through a 300 μm sieve, and obtain pretreated secondary aluminum ash; Step two: wash, filter, and dry the pretreated secondary aluminum ash to obtain washed secondary aluminum ash; The washing process is as follows: Q1: divide the pretreated secondary aluminum ash into three equal parts, respectively, and put them into the first, second, and third reaction kettles; add deionized water to the third reaction kettle, the liquid-solid ratio is 11:1.05, heat and stir at 85°C for 2h, after the reaction is completed, separate the solid and liquid, pump the obtained third-stage washing liquid into the second reaction kettle, at the same time, add deionized water to the second reaction kettle, continue to heat and stir, after the solid-liquid separation, pump the obtained second-stage washing liquid into the first reaction kettle, at the same time, add deionized water to the first reaction kettle, after heating and stirring, separate the solid and liquid, obtain the first-stage washing liquid, and send it to the wastewater collection tank for collection; Q2: add deionized water to the third reaction kettle for washing, after the solid-liquid separation, continue to pump the washing liquid into the second reaction kettle for washing, then continue to pump the washing liquid into the first reaction kettle, and then send the washed washing liquid to the wastewater collection tank for collection, repeat the operation until the ammonia nitrogen concentration in the washing liquid tends to be stable and no longer significantly increases, and at the same time, the wastewater in the wastewater collection tank is recovered and treated, in the recovery and treatment process, first filter the wastewater to remove suspended particles, collect them in the adjustment tank, and then pump them into the water purification tank of the stripping tower, add sodium hydroxide, stir vigorously, adjust the pH to 10.5, then uniformly spray them into the packed tower, at the same time, blow steam from the bottom of the tower, and the treated wastewater is discharged from the bottom of the tower, collected and used for washing in the first reaction kettle, and the discharged gas enters the absorption tower, is sprayed and absorbed with clean water at the top of the tower, and the byproduct is collected and used; Step three: add 1.15g of modified catalyst to 7g of washed secondary aluminum ash, add 46mL of distilled water, stir, seal the reaction kettle, heat and stir at 0.2MPa and 105°C for 4h under nitrogen environment, after the reaction is completed, filter to obtain the filtrate, transfer it to the first reactor in the three-stage series stirred tank reactor, add saturated sodium carbonate solution to the first reactor, control the pH to 3.2 and the temperature to 85°C, then overflow to the second reactor, continue to add saturated sodium carbonate solution, control the pH to 4.3 and the temperature to 92°C, and the time to 2h, finally enter the third reactor, stop adding saturated sodium carbonate solution, and the temperature is 89°C, the aging time is 3h, and the polyaluminum chloride water purifying agent is obtained.

[0031] Comparative Example 1: Comparative Example 1 is compared with Example 1. In the process of preparing polyaluminum chloride water purifying agent, in step two, deionized water is directly used for washing (the amount of deionized water is the same as that in the washing process of Example 1), and steps Q1 and Q2 are not used, and other conditions are unchanged.

[0032] Comparative Example 2: Comparative Example 2 is compared with Example 1. In the process of preparing polyaluminum chloride water purifying agent, in step three, hydrochloric acid with a concentration of 18% is used instead of a modified catalyst, and other conditions are unchanged.

[0033] Performance test: The raw polyaluminum chloride water purifying agent prepared by Examples 1-5 and Comparative Examples 1-2 is subjected to performance test, and the performance of the sample is tested according to GB / T 22627-2022, and the test results are shown in Table 1: Table 1 As can be seen from the test results in Table 1, by using the method of Examples 1-5, a high-performance polyaluminum chloride product with high efficiency and stability can be prepared, and Examples 1-5 perform excellently in terms of salt base, density, pH value, aluminum oxide mass fraction, insoluble mass fraction and ammonia nitrogen mass fraction, which is mainly due to the use of multi-stage series maturation process and the addition of modified catalyst, which ensures the high purity and low impurity content of the product. It can be found from the comparison between Comparative Example 1 and Examples 1-5 that the same washing process is not used, the soluble impurities in the raw material interfere with the hydrolysis polymerization reaction, resulting in lower salt base and aluminum oxide mass fraction than Examples 1-5, and the mass fraction of insoluble and ammonia nitrogen is significantly increased; it can be found from the comparison between Comparative Example 2 and Examples 1-5 that the acid dissolution process using hydrochloric acid is used, the reaction is violent and difficult to control the polymerization process, mainly generating monomer or oligomeric aluminum, the salt base is the lowest, the density, aluminum content and pH are in poor condition, although the impurities are dissolved by hydrochloric acid, but new insoluble substances may be produced, thereby causing the insoluble content to be higher than that of Examples 1-5; the heavy metal content of the samples obtained by the examples and comparative examples is not much different and meets the standard requirements, which is mainly due to the secondary aluminum ash raw material itself.

[0034] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical scheme and inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

[0035] The preferred embodiments of the application disclosed above are only to facilitate the elucidation of the application. The preferred embodiments do not describe all the details of the application and limit the application to the specific embodiments. Obviously, many modifications and variations can be made in light of the teachings above. The description is chosen and described in order to provide the best illustration of the application and its practical application to those skilled in the art and to enable those skilled in the art to utilize the application in its best mode. The application is only limited by the claims and their full scope and equivalents.

Claims

1. A process for the continuous preparation of polyaluminum chloride water purifying agent, characterized in that, The method comprises the following steps: Step one: put the secondary aluminum ash into a mortar for grinding, and sieve to obtain pretreated secondary aluminum ash; Step two: wash the pretreated secondary aluminum ash, filter and dry to obtain washed secondary aluminum ash; Step three: add a modified catalyst to the washed secondary aluminum ash, add distilled water for stirring, seal a reaction kettle, and heat and stir under a nitrogen environment for reaction; after the reaction, filter to obtain a filtrate, transfer the filtrate to a reactor, add saturated sodium carbonate solution, and mature to obtain polyaluminum chloride water purifier.

2. The continuous preparation process of polyaluminum chloride water purifying agent according to claim 1, characterized in that, In the step one, the sieving particle size is 250-320 μm.

3. The process according to claim 1, characterized in that, In the step two, the washing process is as follows: Q1: divide the pretreated secondary aluminum ash into three parts, and respectively put into a first, a second and a third reaction kettle; add deionized water to the third reaction kettle, heat and stir for reaction; after the reaction, separate the solid and the liquid, pump the obtained third washing liquid to the second reaction kettle, at the same time, add deionized water to the second reaction kettle, continue to heat and stir for reaction, and after the solid-liquid separation, pump the obtained second washing liquid to the first reaction kettle, at the same time, add deionized water to the first reaction kettle, heat and stir for reaction, and after the solid-liquid separation, obtain the first washing liquid and send it to a wastewater collection tank for collection; Q2: add deionized water to the third reaction kettle for washing, after the solid-liquid separation, continue to pump the washing liquid to the second reaction kettle for washing, then continue to pump the washing liquid to the first reaction kettle, and then send the washed washing liquid to the wastewater collection tank for collection, repeat the operation, and at the same time, recycle the wastewater in the wastewater collection tank.

4. The continuous preparation process of polyaluminum chloride water purifying agent according to claim 3, characterized in that, In the Q1, after adding deionized water to the third reaction kettle, the liquid-solid ratio is (8-13):(1-1.2), the heating and stirring reaction temperature is 85-95 ℃, and the reaction time is 1-5 h; in the Q2, the washing is ended when the ammonia nitrogen concentration in the washing liquid tends to be stable and no longer significantly increases.

5. The continuous preparation process of polyaluminum chloride water purifying agent according to claim 3, characterized in that, In the Q2, in the recycling process, first filter the wastewater to remove suspended particles, collect in an adjusting tank, and then pump into a water purification tank of a stripping tower, add sodium hydroxide, and stir vigorously to adjust pH to 10.5-11.5, then uniformly spray into a filler tower, at the same time, blow steam from the bottom of the tower, and the treated wastewater is discharged from the bottom of the tower for use in the first reaction kettle, and the discharged gas enters an absorption tower, and at the top of the tower, water is sprayed for absorption to obtain a byproduct, which is collected for self-use.

6. The process according to claim 1, wherein the process is characterized by, In the step three, the preparation method of the modified catalyst comprises the following steps: S1: add dichloroethane, benzene and benzylamine into a container in sequence, ice-bath stir, then add dimethoxymethane and anhydrous ferric chloride, stir at room temperature under a nitrogen environment, then continue to heat and stir, then continue to heat and stir, after the reaction, cool, wash, filter, Soxhlet extraction, alkalization, wash, filter, and vacuum dry to obtain a brown powder. S2: The brown powder was added to a container containing dichloroethane, swelled, and then slowly added dropwise to a dichloromethane solution containing chlorosulfonic acid under ice-salt bath conditions, heated and stirred under a nitrogen atmosphere, after the reaction was completed, cooled, poured into ice water to quench the reaction, washed, filtered, extracted, and vacuum dried to obtain a modified catalyst.

7. The continuous preparation process of polyaluminum chloride water purifying agent according to claim 6, characterized in that, In the S1, the amount ratio of dichloroethane, benzene, benzylamine, dimethoxymethane and anhydrous ferric chloride was (50-75) mL: (1.664-1.882) mL: (0.683-0.924) mL: (6.08-6.24) mL: (11.15-12.03) g.

8. The continuous preparation process of polyaluminum chloride water purifying agent according to claim 6, characterized in that, In the S2, the amount ratio of brown powder, dichloroethane, chlorosulfonic acid and dichloromethane was (0.5-0.7) g: (15-19) mL: (0.25-0.32) mL: (10-12) mL.

9. The process according to claim 1, wherein the process is characterized by, In the step three, the amount ratio of modified catalyst, water-washed secondary aluminum ash and distilled water was (1-1.2) g: (5-8) g: (30-48) mL, the reaction temperature was 105-120℃, the pressure was 0.2-0.5 MPa, the time was 2-4 h, the reactor was the first stage in a three-stage series stirred tank reactor, saturated sodium carbonate solution was added to the first stage reactor, the pH was controlled at 3-3.5, the temperature was 85-90℃, then overflowed to the second stage reactor, saturated sodium carbonate solution was continuously added, the pH was controlled at 4-4.3, the temperature was 90-95℃, the time was 1-2 h, finally entered into the third stage reactor, the saturated sodium carbonate solution was stopped, the temperature was 88-90℃, and the aging time was 2-3 h.

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