Process for direct solid-state recovery of ammonia from ammonium salt-containing waste residues

Abstract

The present application belongs to the field of industrial solid waste treatment, and discloses a process for directly recovering ammonia from ammonium salt-containing waste residue in solid state. First, the ammonium salt-containing waste residue after dewatering by pressure filtration is mixed with calcium hydroxide and fed into a high-shear homogenizing device for mixing, pre-homogenizing, homogenizing and granulating. The ammonium salt-containing waste residue-calcium hydroxide mixture after mixing, homogenizing and granulating is aged in a chain plate deamination device to make ammonium ions react with calcium hydroxide to generate NH3 and escape with water vapor. Finally, the NH3-containing water vapor in the chain plate deamination device is collected and condensed to obtain low-concentration ammonia water. The method and device of the present application can partially dewater the ammonium salt-containing waste residue without consuming fresh water, and can collect and condense the ammonia-containing water vapor to obtain low-concentration ammonia water which is directly returned to the front-end main process. The ammonium salt-containing waste residue has high deamination efficiency, the obtained ammonia-containing water vapor has high recovery rate, no fresh water is consumed, no secondary pollution is generated, the operation cost is low, and the present application has good industrial application value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of industrial solid waste treatment, and relates to a process for solid-state recovery of ammonia from ammonium salt-containing waste residue, in particular to a process for treating residual ammonium sulfate in metallurgical and chemical solid waste such as electrolytic manganese filter cake. BACKGROUND

[0002] In the metallurgical and chemical industries, the waste residue produced by pressure filtration after pH adjustment with ammonia water usually contains about 1% of ammonium ions and 12-30% of water. At present, enterprises have not found a proper method for disposing of such waste residue, and generally transport it to a stockyard or tailings repository for storage. The long-term storage of ammonium salt-containing waste residue under the action of natural factors such as rainwater leaching, the ammonia nitrogen and other harmful substances in the waste residue seriously pollute the soil, surface water and groundwater around the stockyard or tailings repository through surface runoff and percolation. The composition of the leachate from the ammonium salt-containing waste residue is complex and changes greatly, resulting in a complex disposal process and high cost. Therefore, the removal of ammonia nitrogen from the ammonium salt-containing waste residue can solve the problem of the generation of ammonia-containing leachate during the storage process from the source.

[0003] At present, the filter cake usually has a water content of less than 25%, and the ammonium salt is adsorbed on the surface or inside the pores of the solid particles. The filter cake with a water content of less than 25% is in a state of aggregation, and it is difficult to mix uniformly with alkaline powders such as calcium hydroxide for removing the ammonium salt. Moreover, the solubility of calcium hydroxide in aqueous solution is low, and the direct addition of alkali for ammonium removal takes a long time, making it difficult to completely and directly remove ammonium by solid-state and recover ammonia. The conventional process for treating such ammonium salt-containing solid waste in industry is to wash the waste residue with water after slurry preparation or to add calcium hydroxide after slurry preparation for removing residual ammonium salt, i.e. to remove the ammonium salt by mixing the waste residue, lime and water to form a slurry in a fluidized state, so that the ammonia nitrogen enters the water, and then to recover the ammonia by blowing ammonia. The ammonia nitrogen wastewater generated in this process cannot be balanced during the process, and the disposal cost is high.

[0004] Chinese Patent 201910934265.1 discloses a harmless and resourceful disposal system for electrolytic manganese residue. The electrolytic manganese residue is crushed, slurried in a slurry tank, and then repeatedly washed by multiple sets of thickeners and stirred leaching tanks to remove ammonium ions therein, and then dewatered by a filter press to obtain harmless manganese residue and filtrate. This process is complex, does not recover and utilize the ammonia nitrogen in the washing liquid, and the wastewater generated in the washing process cannot be balanced, causing the problem of secondary pollution of wastewater.

[0005] Chinese Patent 202010384541.4 discloses a method for removing ammonia nitrogen from electrolytic manganese residue. The method takes manganese filter cake as the object, adds alkaline compounds such as lime for slurry preparation to remove ammonium, and then dries to prepare cement admixture. This process causes the problem of unorganized emission of gaseous ammonia, and the recycling of washing water is difficult, which is an environmental problem that is difficult to solve in industrial engineering. SUMMARY

[0006] In view of the problems in the prior art, the present application aims to provide a process for directly recovering ammonia from ammonium salt-containing waste residues in solid state, which has high ammonia removal efficiency, can obtain low-concentration ammonia water for use in a front-end process, does not consume fresh water, does not produce secondary pollution, and has good industrial application value.

[0007] To achieve the object of the present application, the specific technical solutions are as follows:

[0008] The process for recovering ammonia from ammonium salt-containing waste residues in solid state uses an ammonium salt-containing waste residue solid-state ammonia recovery system, which comprises, in pipeline communication, a high-shear homogenization device, a chain plate ammonia removal device, and an ammonia-containing water vapor recovery device.

[0009] The high-shear homogenization device comprises a high-shear homogenization feed port, a high-shear homogenization discharge port, and, connected in sequence between the high-shear homogenization feed port and the high-shear homogenization discharge port, a double-screw high-speed kneading unit, a pair of roller secondary mixing unit, and a double-screw homogenization unit.

[0010] The chain plate ammonia removal device comprises a housing, a heating system, and a chain plate conveying system arranged in the housing, and the housing is provided with a chain plate ammonia removal feed port, a chain plate ammonia removal discharge port, and a water vapor outlet.

[0011] The ammonia-containing water vapor recovery system comprises a gas extraction pipeline, an air extractor, a heat exchanger, and an ammonia water collection tank in communication with the water vapor outlet.

[0012] The process for recovering ammonia from ammonium salt-containing waste residues in solid state comprises the following steps:

[0013] (1) Mixing and homogenization: ammonium salt-containing waste residues dewatered by pressure filtration and calcium hydroxide or calcium oxide are fed into the high-shear homogenization device for mixing, pre-homogenization, homogenization, and granulation.

[0014] (2) Heat preservation and aging: the ammonium salt-containing waste residue-lime mixture after mixing and homogenization is heat preserved and aged in the chain plate ammonia removal device, so that the ammonium ions react with calcium hydroxide to generate NH3, which escapes with water vapor.

[0015] (3) Ammonia-containing vapor recovery: the NH3-containing water vapor in the chain plate ammonia removal device is collected and condensed to obtain low-concentration ammonia water.

[0016] To avoid ammonia leakage and pollution of the surrounding environment, and to further harm to the human body and the environment, the high-shear homogenization device of the present application uses sealed pipeline feed and material-closed discharge ports to form a fully enclosed device to prevent gaseous ammonia from overflowing.

[0017] Further, the high-shear homogenization outlet of the high-shear homogenization device is provided with a cutting device; preferably, the cutting device comprises a double-screw extrusion die head and a blade, the material extrusion outlet of the double-screw extrusion die head is square or circular, the outlet size is determined according to the material processing capacity and the material properties, the material is cut into small particles with a length of 0.5-2.5 cm by the cutting blade after passing through the double-screw extrusion die head, and then enters the chain plate deamination device; further preferably, the small particle material obtained after cutting by the blade has a length of 0.8-1.5 cm.

[0018] Further, the double-screw high-speed kneading unit comprises a barrel one closed at both ends, a screw one arranged in the barrel one, and a driving motor one driving the screw one, the feeding port of the barrel one is a high-shear homogenization feeding port, the discharging port of the barrel one is communicated with the pair of roller secondary mixing unit, the screw one is formed by two parallel screws meshing, and the rotation directions are one of the same direction or different directions. The material enters the barrel one of the double-screw high-speed kneading unit through the high-shear homogenization feeding port, the driving motor one is started to drive the screw one, and the material is efficiently dispersed and pre-homogenized in the barrel one.

[0019] Further, the pair of roller secondary mixing unit comprises a closed machine shell, a compression roller arranged in the closed machine shell, and a driving motor three driving the compression roller, the closed machine shell is provided with a mixing feeding port and a mixing discharging port, the mixing feeding port is communicated with the barrel discharging port of the double-screw high-speed kneading unit, and the mixing discharging port is communicated with the double-screw homogenization unit. The material enters the closed machine shell of the pair of roller secondary mixing unit through the mixing feeding port, and the compression roller in the machine shell is driven by the driving motor three to further homogenize the material.

[0020] Further, the double-screw homogenization unit comprises a barrel two closed at both ends, a screw two arranged in the barrel two, and a driving motor two driving the screw two, the feeding port two of the barrel two is communicated with the mixing discharging port of the pair of roller secondary mixing unit, the discharging port two of the barrel two is a high-shear homogenization discharging port, and the screw two is formed by two parallel screws meshing, and the rotation directions are one of the same direction or different directions. The material enters the barrel two of the double-screw homogenization unit, the driving motor two is started to drive the screw two, the material processed by the pair of roller secondary mixing unit is further homogenized and extruded in the barrel two, and small particle material is formed under the action of the cutting device of the discharging port two.

[0021] Further, a distributing device is arranged between the high-shear homogenization device and the chain plate deamination device, the upper end of the distributing device is connected with the high-shear homogenization discharging port, and the lower end of the distributing device is connected with the chain plate deamination device. The material passes through the high-shear homogenization device, and then enters the chain plate deamination device through the distributing device.

[0022] In order to avoid ammonia leakage to pollute the surrounding environment and harm the human body and the environment, the outer periphery of the distributor is further preferably provided with a sealing cover, and the distributor is arranged in the sealing cover to form a sealed material conveying environment.

[0023] Further preferably, the material distributing device is a sloping plate distributor.

[0024] Further, the heating system in the chain plate ammonia removal device is a heat preservation jacket arranged in the shell, which is arranged to heat and keep the material in the shell at a set temperature, and a heat preservation medium is arranged in the heat preservation jacket.

[0025] Further, the heat preservation medium in the heat preservation jacket in the shell of the chain plate ammonia removal device is heat conducting oil, hot water, hot air or hot steam, which is used to keep the material in the chain plate ammonia removal bin at a set temperature, so as to facilitate the reaction of ammonium salt in the ammonium salt-containing waste residue with calcium hydroxide to generate NH3 and be removed with water vapor.

[0026] Further, the chain plate conveying system can adjust the conveying rate under the adjustment of the driving system to control the residence time of the material in the ammonia removal bin.

[0027] The cavity formed in the shell of the chain plate ammonia removal device is the ammonia removal bin, and under the action of the heating system, the material is heated to a process temperature, the diffusion speed of water in the solid material is accelerated, the ammonia generation reaction is accelerated, and part of the water vapor and ammonia enter the upper space of the ammonia removal bin.

[0028] Further, the gas suction pipeline in the ammonia-containing water vapor collection and recovery system is located at the top of the chain plate ammonia removal device, and the water vapor outlet is arranged close to the chain plate ammonia removal inlet. Preferably, in order to facilitate the removal of ammonia, the gas suction pipeline is located at the feeding end of the chain plate ammonia removal device, the distributor is provided with a sealing cover, and the pipe opening of the gas suction pipeline communicates with the sealing cover of the distributor.

[0029] Further, the heat exchanger is a tube type cooling system, and the ammonia-containing water vapor condensation and recovery system sends the gas in the ammonia removal bin to the tube type cooling system through a fan, and under the action of cooling water, the water vapor is cooled to a liquid state, and ammonia also enters the cooling water.

[0030] Further, in the ammonia-containing water vapor condensation and recovery system, the bottom of the heat exchanger is connected to an ammonia water collection tank through a pipeline, and a gravity sensing valve is arranged on the connecting pipeline. When the condensed water reaches a certain amount, the gravity sensing valve is automatically opened, and the condensed liquid flows into the ammonia water collection tank.

[0031] Further, in step (1), the ammonium salt-containing waste residue is a wet smelting residue represented by electrolytic manganese filter cake or a chemical waste residue.

[0032] Further, in step (1), the water content of the ammonium salt-containing waste residue after pressure filtration dewatering is 12-30%, and the mass concentration of ammonium ions is 0.7-2%.

[0033] Further, in step (1), the required calcium hydroxide proportion is determined according to the content of ammonium ions in the waste residue, and is directly added at 1.0-4 times the content of ammonium ions, preferably at 1.2-2.5 times the content of ammonium ions.

[0034] Further, in step (1), the ammonium salt-containing waste residue to which lime is added is uniformly mixed with calcium hydroxide by a high-shear homogenizing device and is granulated, and the granulation size is 0.5-2.5 cm; further preferably 1-1.5 cm.

[0035] Further, in step (1), the mixing and homogenizing time is 1-15 min.

[0036] Further, in step (2), the chain plate deamination device is set to be heat aged, the stacking height on the chain plate is 0.1-1 m, the temperature in the bin is room temperature-200 DEG C, and the residence time is 20 min-10 h.

[0037] Further, in step (2), the mass concentration of ammonia in the material obtained after heat aging and deamination is less than 0.1%, and the water content is 8-15%.

[0038] Further, in step (2), the deamination efficiency of the material obtained after heat aging and deamination can reach more than 90%.

[0039] Further, in step (3), the mass concentration of ammonia in the ammonia water obtained after condensation of the ammonia-containing water vapor in the recovery chain plate deamination device is 4-10%.

[0040] Compared with the prior art, the present application has the following beneficial effects:

[0041] The present application provides a method for directly deaminating ammonium salt-containing waste residue in a solid state and recovering ammonia water, which can deaminate and dewater the ammonium salt-containing waste residue without consuming fresh water, and can collect and condense ammonia-containing water vapor to obtain 4-10% low-concentration ammonia water directly returned to the front-end main process.

[0042] The method has high deamination efficiency for ammonium salt-containing waste residue, high recovery rate of obtained ammonia-containing water vapor, no consumption of fresh water, no secondary pollution, low operation cost, and good industrial application value. BRIEF DESCRIPTION OF DRAWINGS

[0043] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this application. The embodiments of these drawings illustrate the present application and, together with the description, serve to explain the principles of the present application.

[0044] Figure 1 is a structural diagram of a direct solid-state ammonium salt removal system for ammonium salt-containing waste residue according to the present application; Figure 1 Figure 1 is a structural diagram of a direct solid-state ammonium salt removal system for ammonium salt-containing waste residue according to the present application;

[0045] wherein 1 is a double-screw high-speed kneading unit, 10 is a feeding port one, 11 is a barrel one, 12 is a screw one, 13 is a driving motor one, 14 is a discharging port one, 2 is a pair of roller secondary mixing unit, 21 is a closed casing, 22 is a compression roller, 23 is a driving motor three, 24 is a mixing feeding port, 25 is a mixing discharging port, 3 is a double-screw homogenizing unit, 30 is a feeding port two, 31 is a barrel two, 32 is a screw two, 33 is a driving motor two, 34 is a discharging port two, 4 is a material distribution device, 5 is a chain plate deamination device, 51 is a casing, 52 is a chain plate conveying system, 53 is a chain plate deamination discharging port, 54 is a chain plate deamination feeding port, 55 is a water vapor outlet, 6 is an air extractor, 7 is a heat exchanger, 8 is a gravity sensing valve, and 9 is an ammonia water collecting tank. DETAILED DESCRIPTION

[0046] The present application will be described in detail below with reference to the drawings, and the description in this part is only exemplary and explanatory, and should not have any limiting effect on the protection scope of the present application. In addition, those skilled in the art can combine the features in the embodiments and in different embodiments according to the description in the present document.

[0047] Embodiment 1

[0048] Referring to Figure 1 The present embodiment provides a direct solid-state ammonium salt removal system for ammonium salt-containing waste residue, which comprises a high-shear homogenizing device, a chain plate deamination device 5 and an ammonia-containing water vapor recovery device connected in sequence by pipelines.

[0049] The high-shear homogenizing device in the present embodiment is a fully enclosed device, which comprises a high-shear homogenizing feeding port, a high-shear homogenizing discharging port, and a double-screw high-speed kneading unit 1, a pair of roller secondary mixing unit 2 and a double-screw homogenizing unit 3 connected in sequence by pipeline sealing between the high-shear homogenizing feeding port and the high-shear homogenizing discharging port. A cutting device (not shown) is arranged at the high-shear homogenizing discharging port of the high-shear homogenizing device, which comprises a double-screw extrusion die and a blade. The material extrusion outlet of the double-screw extrusion die is square or circular, and the outlet size is determined according to the material processing capacity and the material properties. The material is cut into small particles with a length of 0.5-2.5 cm by the blade after passing through the double-screw extrusion die, and then enters the chain plate deamination device 5 through the material distribution device 4.

[0050] In the embodiment, the double screw high-speed kneading unit 1 comprises a barrel 11 with both ends closed, a screw 12 arranged in the barrel 11, and a driving motor 13 for driving the screw 12. The feeding port 10 of the barrel 11 is designed as a high-shear homogenizing feeding port. The discharging port 14 of the barrel 11 is connected with the pair-roller secondary mixing unit 2. The screw 12 is formed by two parallel screws meshing with each other, and the rotation directions are one of the same direction or the opposite direction. The material enters the barrel 11 of the double screw high-speed kneading unit 1 through the high-shear homogenizing feeding port. The driving motor 13 is turned on to drive the screw 12, and the material is efficiently dispersed and pre-homogenized in the barrel 11.

[0051] In the embodiment, the pair-roller secondary mixing unit 2 comprises a closed machine shell 21, a compression roller 22 arranged in the closed machine shell 21, and a driving motor 23 for driving the compression roller 22. The closed machine shell 21 is provided with a mixing feeding port 24 and a mixing discharging port 25. The mixing feeding port 24 is connected with the discharging port of the barrel 1 of the double screw high-speed kneading unit 1. The mixing discharging port 25 is connected with the double screw homogenizing unit 3. The material enters the closed machine shell 21 of the pair-roller secondary mixing unit 2 through the mixing feeding port 24. Inside the closed machine shell, the compression roller 22 is driven by the driving motor 23 to further homogenize the material.

[0052] In the embodiment, the double screw homogenizing unit 3 comprises a barrel 31 with both ends closed, a screw 32 arranged in the barrel 31, and a driving motor 33 for driving the screw 32. The feeding port 30 of the barrel 31 is connected with the mixing discharging port 25 of the pair-roller secondary mixing unit 2. The discharging port 34 of the barrel 31 is designed as a high-shear homogenizing discharging port. The screw 32 is formed by two parallel screws meshing with each other, and the rotation directions are one of the same direction or the opposite direction. The material enters the barrel 31 of the double screw homogenizing unit 3. The driving motor 33 is turned on to drive the screw 32, and the material processed by the pair-roller secondary mixing unit 2 is further homogenized and extruded in the barrel 31, and small granular material is formed under the action of the cutting device of the discharging port 34.

[0053] In the embodiment, the chain plate deamination device 5 comprises a shell 51, a chain plate conveying system 52 and a heating system arranged in the shell 51, the shell 51 is provided with a chain plate deamination feeding port 54, a chain plate deamination discharging port 53 and a water vapor outlet 55, the chain plate deamination feeding port 54 is communicated with the high shear homogenization discharging port 34 through the distributing device 4; the heating system is a heating jacket arranged in the shell 51, the heating jacket is arranged to heat and keep the materials in the shell 51 at a set temperature, which is beneficial to the reaction of ammonium salt in the ammonium salt-containing waste residue and calcium hydroxide to generate NH3 and be removed with water vapor. In actual use, the residence time of the materials in the chain plate deamination device 5 is adjusted by setting the conveying speed of the chain plate conveying system 52. At the same time, the materials are heated to the process temperature by the heating system, the water diffusion speed in the solid materials is accelerated, and the ammonia generation reaction is accelerated.

[0054] In the embodiment, the distributing device 4 is arranged between the high shear homogenization device and the chain plate deamination device 5, and the distributing device 4 is preferably an inclined plate distributor, the upper end of the distributing device 4 is connected with the high shear homogenization discharging port, and the lower end is connected with the chain plate deamination device 5, the materials pass through the high shear homogenization device and then enter the chain plate deamination device 5 through the distributing device 4. In order to avoid ammonia gas leakage to pollute the surrounding environment and harm the human body and the environment, a sealing cover is arranged on the periphery of the distributing device 4, and the distributing device 4 is located in the sealing cover to form a sealed environment.

[0055] In the embodiment, the ammonia-containing water vapor recovery system comprises an air extraction pipeline communicated with the water vapor outlet 55, an air extractor 6 arranged on the air extraction pipeline, a heat exchanger 7 and an ammonia water collecting tank 9; the device extracts the ammonia-containing water vapor in the chain plate deamination device 5 into the heat exchanger 7 through the air extractor 6 to exchange heat, so that ammonia and water are condensed together to obtain low-concentration ammonia water. The heat exchanger 7 in the embodiment is a shell-and-tube cooling system, which cools the water vapor into liquid state under the action of cooling water, and ammonia also enters the cooling water. In the ammonia-containing water vapor condensation recovery system, the bottom of the heat exchanger 7 is communicated with the ammonia water collecting tank 9 through a pipeline, and a gravity sensing valve 8 is arranged on the communication pipeline. When the condensed water reaches a certain amount, the gravity sensing valve 8 is automatically opened, and the condensed liquid flows into the ammonia water collecting tank 9.

[0056] In the ammonia-containing water vapor collecting and recovering system in the embodiment, the air extraction pipeline port is connected with the water vapor outlet 55 of the chain plate deamination device 5, and the connection position is preferably near the chain plate deamination feeding port 54. The air extraction pipeline port is communicated with the sealing cover on the periphery of the distributing device 4.

[0057] Embodiment 2

[0058] The embodiment provides a solid deamination process for ammonium salt-containing waste residue, and the electrolytic manganese filter cake is prepared. +Ion content is 0.9% (dry basis), moisture content is 25%; using a kind of ammonium salt waste residue in example 1 directly solid state ammonium removal system, the process specifically includes the following steps:

[0059] (1) mixed homogenization: the electrolytic manganese filter cake and slaked lime are fed into the high shear homogenization device, and the theoretical amount of calcium hydroxide is 1.39%. In this example, the theoretical amount of ammonium ion is 2.014 times the amount of slaked lime, that is, the mass of slaked lime is 2.8% of the mass of electrolytic manganese filter cake. The mixture is fed into the barrel one of the high-speed kneading unit of the double screw through the high shear homogenization feed port, the driving motor one is started to drive the screw one, and the ammonium salt waste residue-slaked lime powder is dispersed and pre-homogenized in the barrel one. Then, the mixture is fed into the closed housing of the double roller secondary mixing unit through the mixing feed port. In the housing, the pressure roller is driven by the driving motor three, which can further homogenize the mixture. Finally, the mixture is homogenized and extruded in the barrel two of the double screw homogenization unit by starting the driving motor two to drive the screw two, and the length of the granular material formed by the cutting device at the discharge port is 1 cm. The processing time of mixed homogenization is controlled to be 8 min.

[0060] (2) heat preservation and aging: the mixed homogenized ammonium salt waste residue-slaked lime mixture is sealed and delivered to the chain plate deamination device through the inclined plate distributor in the sealed cover. In the chain plate deamination device, the ammonium ion reacts with calcium hydroxide to generate NH3 and escape with water vapor. The process sets the stacking height in the chain plate conveying system to 0.3 m, adjusts the heating system to control the temperature in the deamination device to 70℃, and adjusts the conveying speed of the chain plate conveying system to make the residence time of the material in the chain plate conveying system to be 40 min.

[0061] (3) ammonia-containing steam recovery: the ammonia-containing water vapor in the chain plate deamination device 5 is extracted by the air extractor and enters the heat exchanger of the ammonia-containing water vapor recovery system for heat exchange, so that ammonia and water are condensed to obtain low-concentration ammonia water. When the amount of low-concentration ammonia water reaches a certain amount, the gravity-sensitive valve 8 is automatically opened, and the ammonia water flows into the ammonia water collection tank 9.

[0062] The ammonia content in the electrolytic manganese filter cake after deamination in this example is 0.072% (dry basis), the moisture content is 15%, the deamination rate is 90.9%, and the concentration of the obtained ammonia water is 6.1%.

[0063] Example 3

[0064] This example provides a kind of ammonium salt waste residue solid state ammonium removal process, prepares electrolytic manganese filter cake, NH4 + Ion content is 0.8% (dry basis), moisture content is 23%; using a kind of ammonium salt waste residue in example 1 directly solid state ammonium removal system, the process specifically includes the following steps:

[0065] (1) mixing and homogenizing: the electrolytic manganese filter cake and slaked lime are fed into a high-shear homogenizing device, and the theoretical amount of calcium hydroxide is 1.39%. In this embodiment, the amount of slaked lime is 2.014 times the theoretical amount of ammonium ion content, i.e., the mass of slaked lime is 2.8% of the mass of electrolytic manganese filter cake. The mixture is fed into the barrel 1 of a high-speed kneading unit of a double screw through a high-shear homogenizing feeding port, and a driving motor 1 is started to drive a screw 1, so that the ammonium salt-containing waste residue and slaked lime powder are dispersed and pre-homogenized in the barrel 1. Then, the mixture is fed into a closed housing of a double roller secondary mixing unit through a mixing feeding port. In the housing, a compression roller is driven by a driving motor 3, so that the mixture is further homogenized. Finally, the mixture is homogenized and extruded in the barrel 2 of a double screw homogenizing unit by starting a driving motor 2 to drive a screw 2, and the mixture is formed into granular materials with a length of 1.2 cm by a cutting device at the discharge port;

[0066] (2) heat preservation and aging: the mixture of the ammonium salt-containing waste residue and slaked lime after mixing and homogenizing is sealed and transferred to a chain plate deamination device through a slope distributor arranged in a sealed cover. The mixture is heat preserved and aged in the chain plate deamination device, so that the ammonium ion reacts with calcium hydroxide to generate NH3, which is discharged with water vapor. In this process, the stacking height in the chain plate conveying system is set to 0.6 m, the temperature in the deamination device is controlled to 60°C by adjusting the heating system, and the residence time of the mixture in the chain plate conveying system is set to 60 min by adjusting the conveying speed of the chain plate conveying system.

[0067] (3) ammonia-containing steam recovery: the ammonia-containing water vapor in the chain plate deamination device 5 is extracted by an air extractor and enters a heat exchanger of an ammonia-containing water vapor recovery system to exchange heat, so that ammonia and water are condensed together to obtain low-concentration ammonia water. When the amount of low-concentration ammonia water reaches a certain amount, a gravity-sensitive valve 8 is automatically opened, and the ammonia water flows into an ammonia water collection tank 9.

[0068] The ammonia content in the electrolytic manganese filter cake after deamination in this embodiment is 0.055% (dry basis), the moisture content is 8.8%, the deamination rate is 93.2%, and the concentration of the obtained ammonia water is 3.68%.

[0069] The above only describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A process for solid state direct recovery of ammonia from ammonium salt containing waste residues, characterized in that, The application discloses a solid-state recovery ammonia system using ammonium salt-containing waste residue, which comprises a high-shear homogenizing device, a chain plate deamination device and an ammonia-containing water vapor recovery device which are sequentially connected through pipelines. The ammonium salt-containing waste residue solid-state direct recovery ammonia process comprises the following steps: (1) mixed homogenization: the ammonium salt-containing waste residue after pressure filtration dehydration is mixed with calcium hydroxide or calcium oxide and then is fed into a high-shear homogenizing device for mixing, pre-homogenization, homogenization and granulation; the required calcium hydroxide is directly added at a percentage of 1.0 to 4.0 times of the theoretical addition amount calculated according to the ammonium ion content in the waste residue; the granulation size is 0.5 to 2.5 cm; (2) heat preservation and aging: the mixed homogenized ammonium salt-containing waste residue-lime mixture is heat preserved and aged in the chain plate deamination device, the temperature in the bin is room temperature to 70 DEG C, the residence time is 20 min to 60 min, the ammonium ion reacts with calcium hydroxide to generate NH3 which escapes with water vapor, the ammonia mass concentration of the material obtained after heat preservation and deamination is less than 0.1%, the water content is 8 to 15%, and the deamination efficiency can reach more than 90%; (3) ammonia-containing steam recovery: the NH3-containing water vapor in the chain plate deamination device is collected and condensed to obtain low-concentration ammonia water with an ammonia mass concentration of 4 to 10%.

2. The process for solid state direct ammonia recovery from ammonium salt containing waste according to claim 1, characterized in that, In step (1), the ammonium salt-containing waste residue is a wet metallurgy residue represented by electrolytic manganese pressure filtration residue or a chemical industry waste residue.

3. The process for solid state direct ammonia recovery from ammonium salt containing waste according to claim 1, characterized in that, In step (1), the water content of the ammonium salt-containing waste residue after pressure filtration dehydration is 12 to 30%, and the ammonium ion mass concentration is 0.7 to 2%.

4. The process for solid state direct ammonia recovery from ammonium salt containing waste according to claim 1, characterized in that, The granulation size is 1 to 1.5 cm.

5. The process for solid state direct ammonia recovery from ammonium salt containing waste according to claim 1, wherein, In step (1), the treatment time of mixed homogenization is 1 to 15 min.

6. The process for solid state direct ammonia recovery from ammonium salt containing waste according to claim 1, wherein, In step (2), the ammonium salt-containing waste residue-calcium hydroxide mixture is heat preserved and aged in the chain plate deamination device, and the material height on the chain plate is 0.1 to 1 m.

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