Method for preparing water purifying agent using waste acid

Abstract

The application discloses a method for preparing water purifying agent by using waste acid, and comprises the following steps: S1, waste aluminum ash pretreatment; S2, waste sulfuric acid neutralization reaction: continue to add waste sulfuric acid into the mixed stirring barrel to obtain secondary mixed solution, adjust the pH value of the secondary mixed solution to 7+ / -0.5, and stir and react for 3-4 hours under normal temperature; S3, deep separation; and S4, deep acidification. The method can collect waste aluminum ash, waste sulfuric acid and waste hydrochloric acid, and only needs to add a small amount of other raw materials to prepare the polyaluminum chloride water purifying agent with high purity, the by-product, pure sodium sulfate solution, can also be reused, waste emission is reduced, the production cost of the polyaluminum chloride water purifying agent is reduced, and the internal structure of the mixed stirring barrel is further optimized, so that the mixed stirring barrel can provide a more simple and efficient treatment process for the method, and the work efficiency is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste acid recycling, in particular to a method for preparing water purifying agent by using waste acid. BACKGROUND

[0002] The overall quality of the environment and the overall pressure of resource consumption in China are very severe at present, and it is urgent to develop circular economy and improve resource utilization and output rate. Pickling is a process commonly used in the metal manufacturing industry, but the amount of waste acid generated is large and harmful. If it is directly discharged without treatment, it will not only cause serious pollution to the environment that cannot be recovered, but also be a great waste of resources, so it is necessary to recycle and reuse the waste acid.

[0003] Polyaluminum chloride water purifying agent has adsorption, coagulation, precipitation and other properties, and has good spray drying stability, wide water range, fast hydrolysis speed, strong adsorption capacity, large alum flower formation, fast dense precipitation, low water turbidity, and good dehydration performance. The spray drying product can ensure safety, reduce water accidents, and is very safe and reliable for drinking water. Therefore, polyaluminum chloride water purifying agent is suitable for raw water of various turbidity and has a wide pH range.

[0004] There are many synthesis methods of polyaluminum chloride. According to different raw materials, it can be divided into metal aluminum method, active aluminum hydroxide method, aluminum oxide method, aluminum chloride method, and alkali dissolution method. Among them, the alkali dissolution method is to react aluminum ash with sodium hydroxide to obtain sodium aluminate solution, and then adjust the pH value with hydrochloric acid to prepare polyaluminum chloride solution. The product prepared by this method has better color appearance and less insoluble matter, but the sodium chloride content is high, the raw material consumption is high, the solution alumina content is low, and the industrial production cost is large. Therefore, how to effectively use waste acid to reduce the cost of preparing polyaluminum chloride water purifying agent by alkali dissolution method is worth further studying. SUMMARY

[0005] In view of the above problems, the present application provides a method for preparing water purifying agent by using waste acid.

[0006] The technical scheme of the present application is:

[0007] A method for preparing water purifying agent by using waste acid, comprising the following steps:

[0008] S1, waste aluminum ash pretreatment: collecting waste aluminum ash, adding waste aluminum ash and sodium hydroxide solution into a mixing and stirring barrel to obtain a first mixed solution, and keeping the pH value of the first mixed solution at 12-13, and stirring and reacting at a temperature of 85-95℃ for 3-4h;

[0009] S2, waste sulfuric acid neutralization reaction: continue to add waste sulfuric acid to the mixed stirring barrel to obtain a secondary mixed solution, adjust the pH value of the secondary mixed solution to 7±0.5, and stir and react at room temperature for 3-4 h;

[0010] S3, deep separation: solid-liquid separation is performed on the secondary mixed solution obtained in step S2 to obtain aluminum hydroxide precipitate and sodium sulfate solution, the aluminum hydroxide precipitate is separated to the upper part of the mixed stirring barrel through the stirring assembly, the sodium sulfate solution is separated to the lower part of the mixed stirring barrel through the stirring assembly, polyaluminum chloride powder and polyacrylamide powder are added to the sodium sulfate solution, the mass fraction of the polyaluminum chloride powder is 10-20% of the sodium sulfate solution, the mass fraction of the polyacrylamide powder is 0.1-0.3% of the sodium sulfate solution, the aluminum hydroxide precipitate is washed with clean water and the washed solution is dropped into the lower part of the mixed stirring barrel, synchronous stirring and reaction is performed for 1-2 h, and pure aluminum hydroxide precipitate and pure sodium sulfate solution are obtained;

[0011] S4, deep acidification: after the pure sodium sulfate solution is discharged, waste acid solution is added to the mixed stirring barrel, the mass of the waste acid solution is 1-4 times the mass of the pure aluminum hydroxide precipitate, the waste acid solution is mixed with the pure aluminum hydroxide precipitate for stirring and reaction for 4-5 h, then sodium hydroxide solution is added to the mixed stirring barrel, and standing and curing is performed for 4-6 h, then sinking and compaction standing is performed for 4-6 h through the stirring assembly, and a polyaluminum chloride mixture is obtained, the polyaluminum chloride mixture is taken out and dried to obtain a PAC water purifying agent.

[0012] Further, the content of aluminum oxide in the waste aluminum ash in step S1 is ≥40%, and the mass concentration of the sodium hydroxide solution is 30-40%.

[0013] Description: By controlling the content of aluminum oxide in the waste aluminum ash, it is ensured that the impurity content in the obtained raw material is not too high.

[0014] Further, the temperature at room temperature in step S2 is 25-28°C.

[0015] Description: The room temperature is relatively easy to achieve.

[0016] Further, the mass concentration of the waste sulfuric acid in step S2 is 20-50%.

[0017] Description: By controlling the mass concentration of the waste sulfuric acid, it is ensured that the waste acid has sufficient sulfuric acid components.

[0018] Further, the mass concentration of hydrochloric acid in the waste acid solution in step S4 is 20-50%, the mass concentration of the sodium hydroxide solution is 5-10%, and the mass of the added sodium hydroxide solution is 5-30% of the total mass of the waste acid solution and the pure aluminum hydroxide precipitate.

[0019] Description: By controlling the mass concentration and the amount of sodium hydroxide, the salt base of the water purifying agent prepared in the deep acidification is improved to meet the national use standard.

[0020] Further, the mixing and stirring barrel is internally provided with a heating assembly, a stirring assembly and a control assembly from bottom to top in sequence, the heating assembly comprises a lower fixed plate and a heater below the lower fixed plate;

[0021] The stirring assembly comprises a main rotating rod and a plurality of auxiliary rotating rods around the main rotating rod, the bottom of the main rotating rod is provided with a plurality of main stirring rods, the bottom of each auxiliary rotating rod is provided with a stirring plate, all the stirring plates are spliced into a sealed annular ring, the outer wall of the annular ring is in close contact with and slidably connected to the inner wall of the mixing and stirring barrel, the auxiliary rotating rods rotate synchronously with the main rotating rod and slide up and down along the sliding grooves provided on the outer wall of the main rotating rod, the bottom of the auxiliary rotating rod is connected to the stirring plate through a sliding block, and the sliding block is slidably and sealingly connected to the sliding groove;

[0022] The control assembly comprises an upper fixed plate, a main motor inside the upper fixed plate for driving the main rotating rod and the auxiliary rotating rods to rotate synchronously, a plurality of electro-hydraulic push rods arranged in a circumferential direction inside the upper fixed plate, a pressing plate provided at the bottom of the electro-hydraulic push rod, and a docking port provided on the upper surface of the stirring plate and corresponding to the pressing plate.

[0023] Description: By further optimizing the internal structure of the mixing and stirring barrel, a more efficient processing process can be provided for the method of the application, the precipitate and the solution at the deep separation can be directly reacted in the mixing and stirring barrel without transfer, and they do not affect each other, thereby greatly improving the work efficiency.

[0024] Further, the number of the auxiliary rotating rods, the sliding grooves, the main stirring rods, the stirring plates and the sliding blocks is 6, the bottom of the stirring plate is provided with a groove for accommodating the main stirring rod, and when the main stirring rod is located in the groove, the bottom of the main stirring rod is flush with the bottom of the stirring plate, one side of the stirring plate is provided with a strip-shaped protrusion, and the other side of the stirring plate is provided with a strip-shaped recess corresponding to the strip-shaped protrusion.

[0025] Description: By optimizing the number of the auxiliary rotating rods, the sliding grooves, the main stirring rods, the stirring plates and the sliding blocks, the number of the stirring plates is minimized to make the control of the stirring plates by the control assembly more simple and reduce the failure rate, while the lifting control of the stirring plates is completed.

[0026] Further, the output end of the main motor is provided with a connecting plate, the bottom center of the connecting plate is connected with the main rotating rod, a plurality of push rod motors are arranged around the connecting plate, the output end of the push rod motor is connected with the auxiliary rotating rod one by one, and the outer wall of the mixing stirring barrel on the side of the control assembly is provided with an exhaust pipe.

[0027] Description: The exhaust pipe is arranged to facilitate the exhaust of waste gas generated in the deep acidification process.

[0028] Further, the inner wall of the docking interface is provided with a limiting ring, when the pressing plate abuts against the limiting ring, the upper surface of the pressing plate is flush with the upper surface of the stirring plate, a filter screen is arranged inside the docking interface below the limiting ring, a liquid inlet pipe and a liquid outlet pipe are arranged on the outer wall of the bottom of the mixing stirring barrel, the inner part of the liquid inlet pipe and the liquid outlet pipe is threadedly connected with a sealing plug, the sealing plug is threadedly connected with the inner wall of the liquid inlet pipe or the liquid outlet pipe, and when the limiting baffle at the tail end of the sealing plug abuts against the outer wall of the mixing stirring barrel, the inner end of the sealing plug is flush with the inner wall of the mixing stirring barrel.

[0029] Description: The arrangement of the docking interface not only enables the spliced stirring plate to realize the filtering function, but also enables the spliced stirring plate to be docked with the pressing plate, so that the spliced stirring plate can complete the compaction of the precipitate, thereby obtaining more detailed and dense water purifying agent particles, and the drying efficiency is improved, the functions are various, the operation is simple, and the method is greatly matched.

[0030] The beneficial effects of the present application are:

[0031] (1) The method for preparing a water purifying agent from waste acid of the present application can prepare a polyaluminum chloride water purifying agent with high purity by collecting waste aluminum slag, waste sulfuric acid and waste hydrochloric acid, only a small amount of other raw materials need to be added, the byproduct of the pure sodium sulfate solution can also be reused, the discharge of waste is reduced, and the production cost of the polyaluminum chloride water purifying agent is reduced.

[0032] (2) The method for preparing a water purifying agent from waste acid of the present application can further optimize the internal structure of the mixing stirring barrel, so that a more simple and efficient treatment process can be provided for the method of the present application, the precipitate and the solution at the deep separation position can be directly reacted in the mixing stirring barrel without being transferred, and they do not affect each other, so that the work efficiency is greatly improved.

[0033] (3) The method for preparing a water purifying agent from waste acid of the present application can realize the filtering function of the spliced stirring plate through the arrangement of a plurality of stirring plates and stirring rods, and the spliced stirring plate can be docked with the pressing plate, so that the spliced stirring plate can complete the compaction of the precipitate, thereby obtaining more detailed and dense water purifying agent particles, and the drying efficiency is improved, the functions are various, the operation is simple, and the method is greatly matched. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a flow chart of a method for preparing a water purifying agent using waste acid according to the present application;

[0035] Figure 2 is a structural schematic diagram of a mixing and stirring barrel in a method for preparing a water purifying agent using waste acid according to the present application;

[0036] Figure 3 is a structural schematic diagram of the inside of a mixing and stirring barrel in a method for preparing a water purifying agent using waste acid according to the present application;

[0037] Figure 4 is a front view of the inside of a mixing and stirring barrel in a method for preparing a water purifying agent using waste acid according to the present application;

[0038] Figure 5 is a structural schematic diagram of a stirring assembly in a method for preparing a water purifying agent using waste acid according to the present application;

[0039] Figure 6 is a structural schematic diagram of the connection between a main rotating rod and a secondary rotating rod in a method for preparing a water purifying agent using waste acid according to the present application;

[0040] Figure 7 is a structural schematic diagram of a stirring plate in a method for preparing a water purifying agent using waste acid according to the present application;

[0041] Figure 8 is a bottom view of all the stirring plates after being spliced in a method for preparing a water purifying agent using waste acid according to the present application;

[0042] Figure 9 is a structural schematic diagram of the connection between a main motor and a main rotating rod, and a push rod motor and a secondary rotating rod in a method for preparing a water purifying agent using waste acid according to the present application;

[0043] Figure 10 is a cross-sectional view of the inside of a connecting port in a method for preparing a water purifying agent using waste acid according to the present application;

[0044] Figure 11 is a structural schematic diagram of the connection between a sealing plug and a liquid inlet pipe in a method for preparing a water purifying agent using waste acid according to the present application.

[0045] 1-mixing barrel, 11-exhaust pipe, 12-liquid inlet pipe, 13-liquid outlet pipe, 2-heating assembly, 21-lower fixed plate, 22-heater, 3-stirring assembly, 31-main rotating rod, 32-vice rotating rod, 33-main stirring rod, 34-sliding slot, 35-sliding block, 4-control assembly, 41-upper fixed plate, 42-main motor, 43-electro-hydraulic push rod, 44-pressing plate, 45-connecting plate, 46-push rod motor, 5-stirring plate, 51-butting port, 52-groove, 53-limiting ring, 54-filter screen, 55-strip-shaped protrusion, 6-sealing plug, 61-limiting baffle. DETAILED DESCRIPTION

[0046] Example 1

[0047] A method for preparing a water purifying agent by using waste acid, as shown in the figure, comprising the following steps: Figure 1 S1, waste aluminum ash pretreatment: collecting waste aluminum ash, adding waste aluminum ash and sodium hydroxide solution into the mixing barrel 1 to obtain a first mixed solution, and keeping the pH value of the first mixed solution at 12.5, and stirring and reacting at 90℃ for 3.5h, the content of aluminum oxide in the waste aluminum ash is 60%, and the mass concentration of the sodium hydroxide solution is 35%;

[0048] S2, waste sulfuric acid neutralization reaction: continue to add waste sulfuric acid into the mixing barrel 1 to obtain a second mixed solution, the mass concentration of the waste sulfuric acid is 30%, and the pH value of the second mixed solution is adjusted to 7, and stirring and reacting at room temperature for 3.5h, the temperature of the room temperature is 26℃;

[0049] S3, deep separation: solid-liquid separation is performed on the second mixed solution obtained in step S2 to obtain aluminum hydroxide precipitate and sodium sulfate solution, the aluminum hydroxide precipitate is separated to the upper part of the mixing barrel 1 by the stirring assembly 3, the sodium sulfate solution is separated to the lower part of the mixing barrel 1 by the stirring assembly 3, polyaluminum chloride powder and polyacrylamide powder are added into the sodium sulfate solution, the mass fraction of the polyaluminum chloride powder added is 15% of the sodium sulfate solution, the mass fraction of the polyacrylamide powder added is 0.2% of the sodium sulfate solution, at the same time, the aluminum hydroxide precipitate is washed with clean water and the washed solution falls into the lower part of the mixing barrel 1, and synchronous stirring and reaction is performed for 1.5h to obtain pure aluminum hydroxide precipitate and pure sodium sulfate solution;

[0050] The stirring assembly 3 is a commercially available stirring rod.

[0051] The stirring assembly 3 is a commercially available stirring rod.

[0052] S4, deep acidification: after the pure sodium sulfate solution is discharged, waste acid solution is added into the mixing and stirring barrel 1, the mass of the waste acid solution is 2 times of the mass of the pure aluminum hydroxide precipitate, the waste acid solution and the pure aluminum hydroxide precipitate are mixed and stirred to react for 4.5 h, then sodium hydroxide solution is added into the mixing and stirring barrel 1, and the mixture is left to mature for 5 h, then the mixture is left to sink and compact through the stirring assembly 3 for 5 h, to obtain a polyaluminum chloride mixture, the polyaluminum chloride mixture is taken out and dried to obtain a PAC water purifying agent, the mass concentration of hydrochloric acid in the waste acid solution is 35%, the mass concentration of the sodium hydroxide solution is 8%, and the mass of the added sodium hydroxide solution is 20% of the total mass of the waste acid solution and the pure aluminum hydroxide precipitate.

[0053] Example 2

[0054] The difference between this example and Example 1 is that the method parameters in step S1 are different.

[0055] S1, waste aluminum ash pretreatment: collect waste aluminum ash, and add the waste aluminum ash and sodium hydroxide solution into the mixing and stirring barrel 1 to obtain a primary mixture, and keep the pH value of the primary mixture at 12, and stir to react at a temperature of 85°C for 3 h, the content of aluminum oxide in the waste aluminum ash is 40%, and the mass concentration of the sodium hydroxide solution is 30%.

[0056] Example 3

[0057] The difference between this example and Example 1 is that the method parameters in step S1 are different.

[0058] S1, waste aluminum ash pretreatment: collect waste aluminum ash, and add the waste aluminum ash and sodium hydroxide solution into the mixing and stirring barrel 1 to obtain a primary mixture, and keep the pH value of the primary mixture at 12, and stir to react at a temperature of 85°C for 3 h, the content of aluminum oxide in the waste aluminum ash is 40%, and the mass concentration of the sodium hydroxide solution is 30%.

[0059] Example 4

[0060] The difference between this example and Example 1 is that the method parameters in step S2 are different.

[0061] S2, waste sulfuric acid neutralization reaction: continue to add waste sulfuric acid into the mixing and stirring barrel 1 to obtain a secondary mixture, the mass concentration of the waste sulfuric acid is 20%, adjust the pH value of the secondary mixture to 6.5, and stir to react at room temperature for 3 h, and the temperature of the room temperature is 25°C.

[0062] Example 5

[0063] The difference between this example and Example 1 is that the method parameters in step S2 are different.

[0064] S2, waste sulfuric acid neutralization reaction: continue to add waste sulfuric acid into the mixing stirring barrel 1 to obtain a secondary mixed solution, the mass concentration of the waste sulfuric acid is 50%, adjust the pH value of the secondary mixed solution to 7.5, and stir and react at room temperature for 4 h, and the temperature at room temperature is 28°C.

[0065] Example 6

[0066] The difference between this example and example 1 is that the method parameters in step S3 are different.

[0067] S3, deep separation: solid-liquid separation is performed on the secondary mixed solution obtained in step S2 to obtain an aluminum hydroxide precipitate and a sodium sulfate solution, the aluminum hydroxide precipitate is separated to the upper part of the mixing stirring barrel 1 through the stirring assembly 3, the sodium sulfate solution is separated to the lower part of the mixing stirring barrel 1 through the stirring assembly 3, polyaluminum chloride powder and polyacrylamide powder are added into the sodium sulfate solution, the mass fraction of the polyaluminum chloride powder is 10% of the sodium sulfate solution, the mass fraction of the polyacrylamide powder is 0.1% of the sodium sulfate solution, the aluminum hydroxide precipitate is washed with clean water at the same time, and the washed solution falls into the lower part of the mixing stirring barrel 1, synchronous stirring reaction is performed for 1 h, and a pure aluminum hydroxide precipitate and a pure sodium sulfate solution are obtained.

[0068] Example 7

[0069] The difference between this example and example 1 is that the method parameters in step S3 are different.

[0070] S3, deep separation: solid-liquid separation is performed on the secondary mixed solution obtained in step S2 to obtain an aluminum hydroxide precipitate and a sodium sulfate solution, the aluminum hydroxide precipitate is separated to the upper part of the mixing stirring barrel 1 through the stirring assembly 3, the sodium sulfate solution is separated to the lower part of the mixing stirring barrel 1 through the stirring assembly 3, polyaluminum chloride powder and polyacrylamide powder are added into the sodium sulfate solution, the mass fraction of the polyaluminum chloride powder is 20% of the sodium sulfate solution, the mass fraction of the polyacrylamide powder is 0.3% of the sodium sulfate solution, the aluminum hydroxide precipitate is washed with clean water at the same time, and the washed solution falls into the lower part of the mixing stirring barrel 1, synchronous stirring reaction is performed for 2 h, and a pure aluminum hydroxide precipitate and a pure sodium sulfate solution are obtained.

[0071] Example 8

[0072] The difference between this example and example 1 is that the method parameters in step S4 are different.

[0073] S4, deep acidification: after the pure sodium sulfate solution is discharged, waste acid solution is added into the mixing and stirring barrel 1, the mass of the waste acid solution is 1 times of the mass of the pure aluminum hydroxide precipitate, the waste acid solution and the pure aluminum hydroxide precipitate are mixed and stirred for 4h, then sodium hydroxide solution is added into the mixing and stirring barrel 1, and is left to mature for 4h, then is settled, compacted and left to stand for 4h through the stirring assembly 3, to obtain a polyaluminum chloride mixture, the polyaluminum chloride mixture is taken out and dried to obtain a PAC water purifying agent, the mass concentration of hydrochloric acid in the waste acid solution is 20%, the mass concentration of sodium hydroxide solution is 5%, and the mass of the added sodium hydroxide solution is 5% of the total mass of the waste acid solution and the pure aluminum hydroxide precipitate.

[0074] Example 9

[0075] The difference between this embodiment and example 1 is that the method parameters in step S4 are different.

[0076] S4, deep acidification: after the pure sodium sulfate solution is discharged, waste acid solution is added into the mixing and stirring barrel 1, the mass of the waste acid solution is 4 times of the mass of the pure aluminum hydroxide precipitate, the waste acid solution and the pure aluminum hydroxide precipitate are mixed and stirred for 5h, then sodium hydroxide solution is added into the mixing and stirring barrel 1, and is left to mature for 6h, then is settled, compacted and left to stand for 6h through the stirring assembly 3, to obtain a polyaluminum chloride mixture, the polyaluminum chloride mixture is taken out and dried to obtain a PAC water purifying agent, the mass concentration of hydrochloric acid in the waste acid solution is 50%, the mass concentration of sodium hydroxide solution is 10%, and the mass of the added sodium hydroxide solution is 30% of the total mass of the waste acid solution and the pure aluminum hydroxide precipitate.

[0077] Example 10

[0078] This embodiment is further optimized on the internal structure of the mixing and stirring barrel on the basis of example 1, as shown in Figure 2 , 3 The inside of the mixing and stirring barrel 1 is sequentially provided with a heating assembly 2, a stirring assembly 3 and a control assembly 4 from bottom to top, the heating assembly 2 comprises a lower fixed plate 21 and a heater 22 located below the lower fixed plate 21;

[0079] As shown in Figures 3 to 7 , the stirring assembly 3 comprises a main rotating rod 31 and a plurality of auxiliary rotating rods 32 located around the main rotating rod 31, the bottom of the main rotating rod 31 is provided with a plurality of main stirring rods 33, and each auxiliary rotating rod 32 is provided with a stirring plate 5 at the bottom, all the stirring plates 5 are spliced into a sealed annular ring, and the outer wall of the spliced annular ring is in close contact and sliding connection with the inner wall of the mixing and stirring barrel 1, the auxiliary rotating rods 32 rotate synchronously with the main rotating rod 31 and slide up and down along the sliding groove 34 provided on the outer wall of the main rotating rod 31, the bottom of the auxiliary rotating rod 32 is connected with the stirring plate 5 through a sliding block 35, and the sliding block 35 is in sliding and sealing connection with the sliding groove 34;

[0080] As shown in Figure 7 , 8 , the number of the auxiliary rotating rods 32, the sliding grooves 34, the main stirring rods 33, the stirring plates 5 and the sliding blocks 35 is 6, the bottom of the stirring plate 5 is provided with a groove 52 for accommodating the main stirring rod 33, and the bottom of the main stirring rod 33 is flush with the bottom of the stirring plate 5 when the main stirring rod 33 is located inside the groove 52, one side of the stirring plate 5 is provided with a strip-shaped protrusion 55, and the other side of the stirring plate 5 is provided with a strip-shaped recess which is in butt joint with the strip-shaped protrusion 55;

[0081] As shown in Figures 3 to 5 , 9-11, the control assembly 4 comprises an upper fixed plate 41, a main motor 42 located inside the upper fixed plate 41 for driving the main rotating rod 31 and the auxiliary rotating rod 32 to rotate synchronously, a plurality of electro-hydraulic push rods 43 which are arranged in a circumferential direction and are located inside the upper fixed plate 41, a pressing plate 44 provided at the bottom of the electro-hydraulic push rod 43, the pressing plate 44 corresponding to the position of the stirring plate 5 one by one, and the upper surface of the stirring plate 5 being provided with a butt joint 51 which is in butt joint with the pressing plate 44, the output end of the main motor 42 being provided with a connecting plate 45, the center of the bottom of the connecting plate 45 being connected with the main rotating rod 31, a plurality of push rod motors 46 being arranged around the connecting plate 45, the output end of the push rod motor 46 being connected with the auxiliary rotating rod 32 one by one, the outer wall of the mixing and stirring barrel 1 located at one side of the control assembly 4 being provided with an exhaust pipe 11, the inner wall of the butt joint 51 being provided with a limiting ring 53, the upper surface of the pressing plate 44 being flush with the upper surface of the stirring plate 5 when the pressing plate 44 and the limiting ring 53 abut each other, a filter screen 54 being provided inside the butt joint 51 below the limiting ring 53, an inlet pipe 12 and a discharge pipe 13 being provided at the outer wall of the bottom of the mixing and stirring barrel 1, the inlet pipe 12 and the discharge pipe 13 being both provided with a sealing plug 6 which is threadedly connected, the sealing plug 6 being threadedly connected with the inner wall of the inlet pipe 12 or the discharge pipe 13, and the inner end of the sealing plug 6 being flush with the inner wall of the mixing and stirring barrel 1 when the limiting baffle 61 at the end of the sealing plug 6 is in butt joint with the outer wall of the mixing and stirring barrel 1.

[0082] The main motor 42, the electro-hydraulic push rod 43, the push rod motor 46 and the heater 22 are all commercially available products.

[0083] Example 11

[0084] The difference between this embodiment and example 10 is that:

[0085] The number of the auxiliary rotating rods 32, the sliding grooves 34, the main stirring rods 33, the stirring plates 5 and the sliding blocks 35 is 8.

[0086] Working principle: the working principle of each component inside the mixing and stirring barrel 1 of the present application will be briefly described in combination with the method of the present application.

[0087] When steps S1 and S2 are performed, the stirring plate 5 needs to be adjusted to be as shown inFigure 3 When the state shown in the middle of the figure is reached, each push rod motor 46 is turned on to drive each sliding block 35 to slide inside the sliding groove 34, so that each stirring plate 5 is arranged at a certain interval, in order to improve the stirring effect;

[0088] When step S3 is performed, the solid-liquid needs to be separated, so first the rotation speed of the main motor 42 is appropriately increased to increase the flow rate inside the mixing and stirring barrel 1, so that the solid substances can fully float, then the stirring plate 5 on one side of the lowest stirring plate 5 is lowered, the push rod motor 46 corresponding to the stirring plate 5 is turned on to drive the corresponding sliding block 35 to slide inside the sliding groove 34, so that the stirring plate 5 is lowered to align with one side of the lowest stirring plate 5, the strip-shaped protrusion 55 corresponds to the strip-shaped recess to keep the two stirring plates 5 sealed, at the same time, the main rotating rod 31 always keeps rotating, and the lowering of each stirring plate 5 is sequentially completed until all the stirring plates 5 are lowered to be flush with the lowest stirring plate 5, forming a circular ring, then the rotation speed of the main motor 42 is lowered, and each push rod motor 46 is simultaneously turned on to drive each sliding block 35 to slide inside the sliding groove 34, so that the circular ring surrounded by each stirring plate 5 rises along the inner wall of the mixing and stirring barrel 1 until it is located in the middle of the mixing and stirring barrel 1, at this time, the liquid in the mixture above the circular ring surrounded by the stirring plates 5 falls into the lower part of the mixing and stirring barrel 1 through the filter screen 54 of each abutting port 51, so that the aluminum hydroxide precipitate above the circular ring surrounded by the stirring plates 5 is reserved, then the aluminum hydroxide precipitate is washed with clean water, and the washed solution falls into the lower part of the mixing and stirring barrel 1, at the same time, polyaluminum chloride powder and polyacrylamide powder are added to the sodium sulfate solution in the lower part of the mixing and stirring barrel 1 for reaction, at this time, the sodium sulfate solution in the lower part of the mixing and stirring barrel 1 can still maintain high-efficiency reaction by the rotation of the main stirring rod 33, and the circular ring surrounded by the stirring plates 5 can also be washed and reacted, the two steps are performed synchronously, and the solution for washing the aluminum hydroxide precipitate can also strengthen the purification of the sodium sulfate solution;

[0089] When the polyaluminum chloride powder and the polyacrylamide powder are added, the liquid inlet pipe 12 is connected with the outside by rotating to open the sealing plug 6, after the addition, the sealing plug 6 is tightly screwed to make the inner end of the sealing plug 6 correspondingly fit the angle radian of the inner wall of the mixing and stirring barrel 1, so that the circular ring surrounded by the stirring plates 5 can move up and down;

[0090] When step S4 is performed, first, the pure sodium sulfate solution in the lower part of the mixing and stirring barrel 1 is discharged, then each stirring plate 5 is reset to the same position as the above-mentioned method Figure 3As shown in the state, after the waste acid solution is added, the pure aluminum hydroxide precipitate is mixed with the waste acid solution under the rotation of the main rotating rod 31 to start the reaction, when the reaction is completed, the rotation speed of the main motor 42 is appropriately increased to strengthen the flow rate inside the mixing and stirring barrel 1, so that the solid substance is fully floated, then the stirring plate 5 on the side of the uppermost stirring plate 5 is lifted, the push rod motor 46 corresponding to the stirring plate 5 is started to drive the sliding block 35 to slide in the sliding groove 34, so that the stirring plate 5 is lifted to be aligned with the side of the uppermost stirring plate 5, the strip-shaped protrusion 55 corresponds to the strip-shaped recess to keep the two stirring plates 5 sealed, at the same time, the main rotating rod 31 always rotates, the lifting of each stirring plate 5 is sequentially completed, until all the stirring plates 5 are lifted to be flush with the uppermost stirring plate 5, forming a ring, then the rotation speed of the main motor 42 is reduced, and each push rod motor 46 is started synchronously to drive each sliding block 35 to slide in the sliding groove 34, so that the ring surrounded by each stirring plate 5 descends along the inner wall of the mixing and stirring barrel 1 until the bottom of the mixing and stirring barrel 1, at this time, the precipitate is below the ring surrounded by the stirring plates 5, and the liquid moves above the ring surrounded by the stirring plates 5 through the filter screen, after the liquid is discharged, the standing and curing are completed, then the electro-hydraulic push rod 43 is started to drive each pressing plate 44 to descend to be aligned with the butt joint 51, and each stirring plate 5 is pressed down under the action of the limiting ring 53, and the sinking and compaction standing process is completed under the interaction with the lower fixed plate 21.

[0091] Experimental example

[0092] The PAC water purifying agent prepared by the method in Embodiment 10 and the mixing and stirring barrel 1 is used to treat wastewater containing COD, and the result shows that the removal rate of the prepared PAC water purifying agent to COD reaches 17.8%, while the average removal rate of various water purifying agents on the market to COD is 16%, therefore, the method of the application combined with the PAC water purifying agent prepared by the mixing and stirring barrel 1 of the application can meet the use requirements.

Claims

1. A method for preparing a water purifying agent using waste acid, characterized by, The method comprises the following steps: S1, waste aluminum ash pretreatment: collecting waste aluminum ash, adding the waste aluminum ash and sodium hydroxide solution into a mixing stirring barrel (1) to obtain a primary mixed solution, keeping the pH value of the primary mixed solution at 12-13, and stirring and reacting at a temperature of 85-95°C for 3-4h; S2, waste sulfuric acid neutralization reaction: continuously adding waste sulfuric acid into the mixing stirring barrel (1) to obtain a secondary mixed solution, adjusting the pH value of the secondary mixed solution to 7±0.5, and stirring and reacting at room temperature for 3-4h; S3, deep separation: performing solid-liquid separation on the secondary mixed solution obtained in step S2 to obtain aluminum hydroxide precipitate and sodium sulfate solution, separating the aluminum hydroxide precipitate to the upper part of the mixing stirring barrel (1) through the stirring assembly (3), separating the sodium sulfate solution to the lower part of the mixing stirring barrel (1) through the stirring assembly (3), adding polyaluminum chloride powder and polyacrylamide powder into the sodium sulfate solution, the mass fraction of the polyaluminum chloride powder being 10-20% of the sodium sulfate solution, the mass fraction of the polyacrylamide powder being 0.1-0.3% of the sodium sulfate solution, rinsing the aluminum hydroxide precipitate with clean water and dropping the rinsed solution into the lower part of the mixing stirring barrel (1), and synchronously stirring and reacting for 1-2h to obtain pure aluminum hydroxide precipitate and pure sodium sulfate solution; S4, deep acidification: after the pure sodium sulfate solution is discharged, adding waste acid liquid into the mixing stirring barrel (1), the mass of the waste acid liquid being 1-4 times the mass of the pure aluminum hydroxide precipitate, stirring and reacting the waste acid liquid and the pure aluminum hydroxide precipitate for 4-5h, then adding sodium hydroxide solution into the mixing stirring barrel (1), standing and aging for 4-6h, then sinking and compacting through the stirring assembly (3) and standing for 4-6h to obtain polyaluminum chloride mixture, and drying the polyaluminum chloride mixture to obtain PAC water purifying agent; The mass concentration of hydrochloric acid in the waste acid liquid in step S4 is 20-50%; The mixing stirring barrel (1) is internally provided with a heating assembly (2), a stirring assembly (3) and a control assembly (4) from bottom to top in sequence, and the heating assembly (2) comprises a lower fixed plate (21) and a heater (22) below the lower fixed plate (21); The stirring assembly (3) comprises a main rotating rod (31) and a plurality of auxiliary rotating rods (32) around the main rotating rod (31), the bottom of the main rotating rod (31) is provided with a plurality of main stirring rods (33), the bottom of each auxiliary rotating rod (32) is provided with a stirring plate (5), all the stirring plates (5) are spliced into a sealed annular ring, the outer wall of the spliced annular ring is in close contact with and slidably connected to the inner wall of the mixing stirring barrel (1), the auxiliary rotating rods (32) rotate synchronously with the main rotating rod (31) and slide up and down along the sliding grooves (34) provided on the outer wall of the main rotating rod (31), the bottom of the auxiliary rotating rod (32) is connected to the stirring plate (5) through a sliding block (35), and the sliding block (35) is slidably and sealingly connected to the sliding groove (34). The control assembly (4) comprises an upper fixed plate (41), a main motor (42) for driving the main rotating rod (31) and the auxiliary rotating rod (32) to rotate synchronously inside the upper fixed plate (41), a plurality of electro-hydraulic push rods (43) arranged in a circumferential direction inside the upper fixed plate (41), and a pressing plate (44) arranged at the bottom of the electro-hydraulic push rod (43), wherein the pressing plate (44) corresponds to the position of the stirring plate (5) one by one, and the upper surface of the stirring plate (5) is provided with a butt joint (51) for butt joint with the pressing plate (44). The number of the auxiliary rotating rod (32), the sliding groove (34), the main stirring rod (33), the stirring plate (5) and the sliding block (35) is 6, the bottom of the stirring plate (5) is provided with a groove (52) for accommodating the main stirring rod (33), and the bottom of the main stirring rod (33) is flush with the bottom of the stirring plate (5) when the main stirring rod (33) is located inside the groove (52), one side of the stirring plate (5) is provided with a strip-shaped protrusion (55), and the other side of the stirring plate (5) is provided with a strip-shaped recess (55) for butt joint with the strip-shaped protrusion (55).

2. The method for preparing water purifying agent using waste acid according to claim 1, characterized in that, The content of aluminum oxide in the waste aluminum ash in step S1 is greater than or equal to 40%, and the mass concentration of the sodium hydroxide solution is 30-40%.

3. The method for preparing water purifying agent using waste acid according to claim 1, characterized in that, The temperature in step S2 is 25-28°C.

4. The method for preparing water purifying agent using waste acid according to claim 1, characterized in that, The mass concentration of the waste sulfuric acid in step S2 is 20-50%.

5. The method for preparing water purifying agent using waste acid according to claim 1, characterized in that, In step S4, the mass concentration of the sodium hydroxide solution is 5-10%, and the mass of the added sodium hydroxide solution is 5-30% of the total mass of the waste acid solution and the pure aluminum hydroxide precipitate.

6. The method for preparing water purifying agent using waste acid according to claim 1, characterized in that, The output end of the main motor (42) is provided with a connecting plate (45), the center of the bottom of the connecting plate (45) is connected with the main rotating rod (31), a plurality of push rod motors (46) are arranged around the connecting plate (45), the output end of the push rod motor (46) is connected with the auxiliary rotating rod (32) one by one, and the outer wall of the mixing and stirring barrel (1) on one side of the control assembly (4) is provided with an exhaust pipe (11).

7. The method for preparing water purifying agent using waste acid according to claim 1, characterized in that, The inner wall of the butt joint (51) is provided with a limiting ring (53), the upper surface of the pressing plate (44) is flush with the upper surface of the stirring plate (5) when the pressing plate (44) and the limiting ring (53) abut each other, a filter screen (54) is arranged inside the butt joint (51) below the limiting ring (53), a liquid inlet pipe (12) and a liquid outlet pipe (13) are arranged on the outer wall of the bottom of the mixing and stirring barrel (1), the inner wall of the liquid inlet pipe (12) and the liquid outlet pipe (13) is threadedly connected with a sealing plug (6), the sealing plug (6) is threadedly connected with the inner wall of the liquid inlet pipe (12) or the liquid outlet pipe (13), and the inner end of the sealing plug (6) is flush with the inner wall of the mixing and stirring barrel (1) when the limiting baffle (61) at the end of the sealing plug (6) abuts with the outer wall of the mixing and stirring barrel (1).

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