Comprehensive utilization method of secondary aluminum ash

Abstract

The invention relates to the technical field of comprehensive treatment of industrial solid wastes, and particularly discloses a comprehensive utilization method of secondary aluminum ash, which specifically comprises the following steps: deoxidizing the secondary aluminum ash; carrying out hydrolysis treatment on the deoxidized secondary aluminum ash, and carrying out solid-liquid separation to obtain mixed gas, a hydrolysis slurry solid phase and high-salt-alkali ammonia nitrogen hydrolysate; separating and purifying the mixed gas to obtain hydrogen; carrying out at least two times of acid washing treatment and at least one time of alkali washing treatment on the hydrolyzed slurry solid phase to obtain a solid phase product for the concrete admixture; and carrying out ammonia-nitrogen separation on the high-salt-alkali ammonia-nitrogen hydrolysate, and carrying out gradient acidification treatment to obtain aluminum hydroxide and inorganic salt crystals. By implementing the method, high-added-value overall utilization of the secondary aluminum ash can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive disposal of industrial solid waste, and in particular to a comprehensive utilization method of secondary aluminum ash. Background Art

[0002] Secondary aluminum ash is the ash produced in the process of remelting primary aluminum ash or waste aluminum to recover elemental aluminum in the secondary aluminum industry. The elemental aluminum content in secondary aluminum ash is between 5-20%. In addition, it also contains aluminum oxide, aluminum nitride, salt (fluoride salt and chloride salt, etc.) and silicon dioxide. The main harmful substance in secondary aluminum ash is aluminum nitride, and there are also a small amount of inorganic salt components such as fluoride, sulfide, sulfate and chloride. Direct discharge will cause serious air, soil and water pollution.

[0003] The disposal methods of secondary aluminum ash are mainly divided into pyrolysis and wet methods (mainly hydrolysis). The wet method includes acid-base treatment, which is to react the secondary aluminum ash with a specific concentration of acid or alkali in the liquid to hydrolyze the aluminum nitride, elemental aluminum and other aluminum compounds. After alkaline treatment, the liquid phase pH is greater than 14, mainly containing aluminates, chlorides, sulfides, sulfates, a small amount of fluorides and ammonia nitrogen, etc. At present, acid or alkaline leaching methods are mostly used to treat secondary aluminum ash, so that aluminum nitride is efficiently hydrolyzed, and soluble salts are leached by acid or alkali, but there are still a large number of recyclable resources in its acidic or alkaline hydrolyzate. The content of heavy metals and impurity ions contained in the secondary aluminum ash treated by hydrolysis has not been significantly reduced, and it cannot be used as an auxiliary cementitious material for concrete, which will bring difficulties to the utilization of the secondary aluminum ash residue after hydrolysis treatment. In addition, the products obtained from the treatment of alkaline aluminum ash hydrolyzate are relatively single, and the resource utilization rate of aluminum ash hydrolyzate is low. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a comprehensive utilization method of secondary aluminum ash, which can realize high value-added resource utilization of secondary aluminum ash and greatly improve its utilization rate.

[0005] In order to solve the above technical problems, the present invention provides a comprehensive utilization method of secondary aluminum ash, which comprises:

[0006] Deoxidize the secondary aluminum ash;

[0007] The deoxidized secondary aluminum ash is subjected to hydrolysis treatment and solid-liquid separation to obtain mixed gas, hydrolysis slurry solid phase and high-salinity alkali ammonia nitrogen hydrolyzate;

[0008] Separating and purifying the mixed gas to obtain hydrogen;

[0009] The hydrolyzed slurry solid phase is subjected to at least two acid washing treatments and at least one alkali washing treatment to obtain a solid phase product for concrete admixture;

[0010] The high-salinity alkaline ammonia nitrogen hydrolyzate is subjected to ammonia nitrogen separation and stepwise acidification treatment to obtain aluminum hydroxide and inorganic salt crystals.

[0011] As an improvement of the above technical solution, in the step of hydrolyzing the deoxidized secondary aluminum ash to obtain a mixed gas, a hydrolysis slurry solid phase and a high-salinity alkali ammonia nitrogen hydrolyzate:

[0012] The secondary aluminum ash is mixed with water at a solid-liquid ratio of 1:(2-10), and calcium hydroxide and a catalyst are added, and hydrolyzed at 5-99°C for 5-48h; the gas collected during the hydrolysis process is the mixed gas, the liquid phase obtained by solid-liquid separation of the hydrolysis product is a high-salinity alkaline ammonia nitrogen hydrolyzate, and the solid phase obtained is a hydrolysis slurry solid phase;

[0013] Wherein, the weight ratio of the calcium hydroxide to the deoxidized secondary aluminum ash is (1-10):100, and the weight ratio of the catalyst to the deoxidized secondary aluminum ash is (1-10):100;

[0014] The catalyst comprises, by weight: 0-10 parts of sodium carbonate, 0-10 parts of potassium carbonate, 10-80 parts of sodium hydroxide, 0-50 parts of potassium hydroxide, 5-30 parts of carbide slag, and 0.01-5 parts of sodium stannate.

[0015] As an improvement of the above technical solution, the temperature during the hydrolysis treatment is carried out according to the following procedure:

[0016] Add secondary aluminum ash, water, catalyst and calcium hydroxide into the reactor. When the temperature in the reactor rises to 70-90°C, cool it with a cooling medium so that the temperature rise rate in the reactor is controlled to be 0.1-3°C / min.

[0017] When the temperature rise rate in the reactor decreases, gradually reduce the amount of cooling medium to maintain the temperature in the reactor at 80-90°C;

[0018] When the temperature in the reactor begins to drop, heating medium is used for heating, and the amount of heating medium is adjusted to maintain the temperature in the reactor at 80-90°C; wherein the difference between the temperature of the heating medium and the temperature in the reactor is 1-10°C.

[0019] As an improvement of the above technical solution, the step of deoxidizing the secondary aluminum ash includes:

[0020] The secondary aluminum ash is graded so that the residue on a 125 μm sieve is 1-10%;

[0021] The secondary aluminum ash is deoxidized by nitrogen replacement.

[0022] As an improvement of the above technical solution, the steps of subjecting the hydrolyzed slurry solid phase to at least two acid washing treatments and at least one alkali washing treatment to obtain a solid phase product for concrete admixture include:

[0023] The hydrolyzed slurry solid phase is subjected to at least two acid washing treatments, and the slurry obtained by the acid washing treatment is subjected to solid-liquid separation to obtain a sub-solid phase and a first sub-liquid phase; the sub-liquid phase is used for the secondary aluminum ash hydrolysis treatment or the last acid washing treatment;

[0024] The sub-solid phase is subjected to at least one alkali washing treatment, and the slurry obtained by the alkali washing treatment is subjected to solid-liquid separation to obtain a solid phase product and a second sub-liquid phase, and the second sub-liquid phase is used for acid washing treatment;

[0025] The content of tracer ions is measured in the slurry after acid washing and alkali washing, and the tracer ions are heavy metals and / or impurity ions;

[0026] The heavy metals include one or more of Pb, Cd, Cr, Cu, Ni, Zn, and Mn, and the impurity ions include Cl - 、F - , K + 、Na + One or more of .

[0027] As an improvement of the above technical solution, the steps of subjecting the hydrolyzed slurry solid phase to at least two acid washing treatments and at least one alkali washing treatment to obtain a solid phase product for concrete admixture include:

[0028] Injecting a first washing liquid into the first washing kettle and sending the hydrolyzed slurry solid phase into the washing kettle, wherein the first washing liquid comes from the second liquid phase after the slurry is filtered out at the outlet of the second washing kettle;

[0029] Passing a first gas into the primary washing kettle until the pH value of the washing liquid reaches a first preset value;

[0030] Passing an acidic solution into the primary washing kettle until the pH of the washing solution reaches a second preset value;

[0031] After the washing in the first washing kettle is completed, the slurry is subjected to solid-liquid separation to obtain a first liquid phase and a first solid phase, wherein the first liquid phase can be used for secondary aluminum ash hydrolysis treatment;

[0032] Injecting a second washing liquid into the secondary washing kettle and sending the first solid phase into the washing kettle for further washing, wherein the second washing liquid comes from the third liquid phase after the mud is filtered out at the outlet of the tertiary washing kettle;

[0033] Passing an acidic solution into the secondary washing kettle until the pH of the washing solution reaches a second preset value;

[0034] After the washing in the secondary washing kettle is completed, the slurry is subjected to solid-liquid separation to obtain a second liquid phase and a second solid phase;

[0035] Injecting a third washing liquid into the tertiary washing kettle and feeding the second solid phase into the kettle for washing, wherein the third washing liquid is water;

[0036] introducing an alkaline substance into the third-stage washing kettle until the pH value of the washing liquid reaches a third preset value;

[0037] After the washing in the three-stage washing kettle is completed, the slurry is subjected to solid-liquid separation to obtain a third liquid phase and a third solid phase;

[0038] The content of heavy metals and impurity ions in the third solid phase is detected. If it meets the specified standards, washing is completed and the third solid phase is the solid phase product. If it does not meet the specified standards, the washing of the three-stage washing kettle is repeated.

[0039] As an improvement of the above technical solution, the solid-liquid ratio of the first-stage washing kettle, the second-stage washing kettle, and the third-stage washing kettle is 1:(3-10) by mass ratio;

[0040] The liquid level of the washing liquid in the first-stage washing kettle, the second-stage washing kettle and the third-stage washing kettle is 50-80% of the internal height of the washing kettle.

[0041] As an improvement of the above technical solution, the first gas is CO2, and the first preset value of pH is 6-7;

[0042] The acidic solution is one or a combination of sulfuric acid, nitric acid, and organic acid, and the second preset pH value is 2-6;

[0043] The alkaline substance is one or a combination of calcium hydroxide, sodium hydroxide and carbide slag, and the third preset value of pH is 7-12.

[0044] As an improvement of the above technical solution, the conditions for determining the end of each washing process include:

[0045] One or more heavy metal or impurity ions are selected as tracer ions and sampling is performed at preset intervals;

[0046] Detecting the content of the tracer ion, if the change of the tracer ion content between two adjacent times is less than the preset ion value, the washing is finished;

[0047] Wherein, the ion preset value is 5-10%.

[0048] As an improvement of the above technical solution, the first-stage washing kettle, the second-stage washing kettle and the third-stage washing kettle are operated with an ultrasonic generator and an agitator for washing, wherein the rotation speed of the agitator is 20-80 r / min, and the ultrasonic frequency of the ultrasonic generator is 20-80 kHz.

[0049] As an improvement of the above technical solution, the steps of separating ammonia nitrogen from the high-salinity alkaline ammonia nitrogen hydrolyzate and performing a stepwise acidification treatment to obtain aluminum hydroxide and inorganic salt crystals include:

[0050] Separating the high-salinity alkaline ammonia nitrogen hydrolyzate to obtain a gas phase and a first-stage liquid phase;

[0051] dissolving carbon dioxide in the first liquid phase until a specified pH value is reached to obtain a second liquid phase;

[0052] dissolving carbon dioxide in the second-stage liquid phase until a specified pH value is reached to obtain a third-stage liquid phase;

[0053] Adding an extraction solvent to the third liquid phase and dissolving carbon dioxide until a specified pH value is reached, and obtaining a fourth liquid phase of an organic phase and a fourth liquid phase of an inorganic phase after extraction and separation;

[0054] Evaporating the water in the fourth liquid phase of the inorganic phase;

[0055] The fourth-stage liquid phase of the organic phase is subjected to back extraction separation to obtain an inorganic liquid phase and an organic liquid phase, the water in the inorganic liquid phase is evaporated, and the organic liquid phase is returned to the treatment of the third-stage liquid phase.

[0056] As an improvement of the above technical solution, in the step of separating ammonia nitrogen from the high-salt alkali ammonia nitrogen hydrolyzate to obtain a gas phase and a first-stage liquid phase:

[0057] The high-salinity alkaline ammonia nitrogen hydrolyzate is introduced into the reactor, the speed of the reactor is set to 40-150r / min, and air is introduced for aeration, with an air flow rate of 10-30m 3 / min, reaction time 0.5-3h, the obtained ammonia gas is passed into an absorption tower to obtain ammonia water;

[0058] The high-salinity alkaline ammonia nitrogen hydrolyzate has a temperature of 80-95°C, an alkalinity of 0.20-2.0 mol / L, a total salt content of 5-25%, and an ammonia nitrogen concentration of 200-2000 mg / L.

[0059] The speed of the reactor is set to 40-150r / min, and air is introduced for aeration, with an air flow rate of 10-30m 3 / min, reaction time 0.5-3h, the obtained ammonia gas is passed into an absorption tower to obtain ammonia water.

[0060] As an improvement of the above technical solution, in the step of dissolving carbon dioxide in the first-stage liquid phase until a specified pH value is reached to obtain a second-stage liquid phase:

[0061] Carbon dioxide is introduced into the first-stage liquid phase, and the carbon dioxide flow rate is set to 1000-3000 mL / min and the rotation speed is set to 30-150 r / min. The reaction is stopped when the reaction pH drops from 12-14 to 7-8, and the slurry is separated into solid and liquid to obtain aluminum hydroxide and the second-stage liquid phase.

[0062] As an improvement of the above technical solution, in the step of dissolving carbon dioxide in the second-stage liquid phase until a specified pH value is reached to obtain a third-stage liquid phase:

[0063] The second-stage liquid phase is transferred to the reactor, and carbon dioxide is introduced into the reactor. The carbon dioxide flow rate is set to 1000-3000mL / min, and the rotation speed is set to 40-150r / min. The reaction is stopped when the reaction pH drops from 7-8 to 5-6, and the slurry is separated into solid and liquid to obtain sodium bicarbonate and the third-stage liquid phase.

[0064] As an improvement of the above technical solution, in the step of adding an extraction solvent to the third liquid phase and dissolving carbon dioxide until a specified pH value is reached, and obtaining a fourth liquid phase of an organic phase and a fourth liquid phase of an inorganic phase after extraction and separation:

[0065] The third liquid phase is transferred to a reaction kettle, carbon dioxide is introduced into the kettle, and an extraction solvent is added at the same time, and the volume ratio of the organic phase:inorganic phase is set to (1-2):(2-3), and the solubility of carbon dioxide is set to 0.05-0.08 mol / L. The reaction is stopped when the reaction pH drops from 5-6 to 3-4, and an organic fourth liquid phase and an inorganic fourth liquid phase are obtained after extraction and separation; the organic fourth liquid phase contains chlorine.

[0066] As an improvement of the above technical solution, the extraction solvent comprises an extractant and a diluent, wherein the extractant is one or more of alkyl primary amine, secondary amine, trioctyl tertiary amine, trioctyl methyl quaternary ammonium salt; the diluent is one or more of kerosene, tributyl phosphate, n-pentanol, n-hexanol, n-octanol, isooctyl alcohol;

[0067] The flow rate of the carbon dioxide is 1000-3000mL / min;

[0068] The rotation speed of the reactor is set to 40-150 r / min, the reaction temperature is 20-25° C., and the reaction pressure is 1-3 Mpa.

[0069] As an improvement of the above technical solution, in the step of evaporating the water in the fourth liquid phase of the inorganic phase:

[0070] The fourth-stage liquid phase of the inorganic phase is discharged from the bottom of the reactor and heated to 90-100° C., and then pumped into the MVR evaporator, and the compressor is started to produce sodium sulfate and mother liquor when the sodium sulfate is supersaturated;

[0071] When the sodium sulfate concentration of the mother liquor is reduced to 3-7% and the temperature is reduced to 45-55°C, the mother liquor is transported to the MVR evaporator, the compressor is turned on, and sodium chloride is obtained after supersaturation concentration.

[0072] As an improvement of the above technical solution, the fourth-level liquid phase of the organic phase is subjected to back extraction separation to obtain an inorganic liquid phase and an organic liquid phase, the water in the inorganic liquid phase is evaporated, and the organic liquid phase is returned to the third-level liquid phase.

[0073] Ammonia water is added to the fourth-level liquid phase of the organic phase, and the volume ratio of the organic phase: the inorganic phase is set to (1-2): (0.5-1), the rotation speed is 40-150r / min, and back extraction separation is performed to obtain an inorganic liquid phase and an organic liquid phase, wherein the water in the inorganic liquid phase is evaporated to obtain ammonium chloride; and the organic liquid phase is returned to the treatment of the third-level liquid phase.

[0074] The implementation of the present invention has the following beneficial effects:

[0075] 1. In the comprehensive utilization method of secondary aluminum ash in the present invention, the secondary aluminum ash is deoxidized and hydrolyzed to obtain a mixed gas, a hydrolysis slurry solid phase and a high-salinity alkali ammonia nitrogen hydrolyzate. The mixed gas is separated and purified to obtain hydrogen, and the hydrolyzed solid phase is subjected to at least two acid washing treatments and at least one intermittent treatment to remove heavy metals and impurity ions, so that it can be used as a concrete admixture. After ammonia nitrogen separation and cascade acidification treatment, the high-salinity alkali ammonia nitrogen hydrolyzate can obtain aluminum hydroxide, as well as inorganic salt crystals such as sodium bicarbonate, sodium chloride, sodium sulfate and ammonium chloride, thereby realizing the high added value utilization of secondary aluminum ash.

[0076] 2. In the comprehensive utilization method of secondary aluminum ash of the present invention, the secondary aluminum ash is first subjected to low-temperature hydrolysis treatment (5-99°C), and then the hydrolysis slurry solid phase obtained by the hydrolysis treatment is subjected to at least two acid washing treatments (room temperature) and at least one alkali washing treatment (room temperature). Based on this technical route, on the one hand, it prevents the temperature from rising suddenly during the hydrolysis process, thereby preventing a large amount of foam from being generated, thereby reducing the difficulty of controlling the hydrolysis reaction. Second, the generation of water vapor is reduced during the low-temperature hydrolysis process, thereby preventing a large amount of water vapor from mixing into the mixed gas, thereby reducing the difficulty of separating the mixed gas in the later stage. Third, impurity ions and heavy metals can be separated through the later acid washing and alkali washing treatments, and the gas-producing impurities in the secondary aluminum ash can be completely decomposed, so that the solid phase product can be used in high value-added concrete.

[0077] 3. In the comprehensive utilization method of secondary aluminum ash in the present invention, a specific temperature control program is adopted according to the characteristics of the hydrolysis reaction of secondary aluminum ash. Specifically, in the early stage of hydrolysis, a cooling medium is introduced for cooling, and in the later stage of hydrolysis, a heating medium is introduced for heating. This makes the reaction temperature control more precise, avoids excessive reaction, reduces the control difficulty, and reduces the difficulty of separating the mixed gas.

[0078] 4. In the comprehensive utilization method of secondary aluminum ash in the present invention, during the treatment process of the hydrolysis mud solid phase, it is washed multiple times, and solid-liquid separation is performed after each washing. The obtained liquid is recycled in the hydrolysis treatment process or the washing treatment process, and the obtained solid is used in concrete, and heavy metals and impurity ions are monitored during each washing process. Based on this process, not only the water consumption is effectively reduced, but also the elution efficiency of heavy metals and impurity ions is improved, which is conducive to the high added value utilization of the hydrolysis mud solid phase.

[0079] Furthermore, the present invention adjusts the pH value of the mud by introducing different substances at different stages, so that heavy metals and impurity ions are dissolved in the liquid phase to the maximum extent, thereby improving the elution efficiency of heavy metals and impurity ions. Moreover, the present invention uses CO2 as a pH regulator, and CO2 is converted into carbonate, realizing a negative carbon process. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 It is a schematic flow diagram of a method for comprehensive utilization of dichloroaluminum ash in one embodiment of the present invention;

[0081] Figure 2 It is a schematic structural diagram of a washing kettle body in one embodiment of the present invention;

[0082] Figure 3 is a schematic diagram of the structure of an aeration tube in one embodiment of the present invention;

[0083] Figure 4 is a flow chart of a method for treating a solid phase of a hydrolyzed slurry in one embodiment of the present invention;

[0084] Figure 5 A flow chart of a method for treating a high-salinity alkaline ammonia nitrogen hydrolyzate in one embodiment of the present invention. DETAILED DESCRIPTION

[0085] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0086] See also Figure 1 The present invention discloses a comprehensive utilization method of secondary aluminum ash, which comprises the following steps:

[0087] S100, deoxidizing the secondary aluminum ash;

[0088] Specifically, deoxidation treatment can be achieved by an inert gas replacement process, but is not limited thereto. Preferably, in one embodiment, the secondary aluminum ash is placed in a reactor and nitrogen is introduced for replacement to achieve deoxidation. Deoxidation can prevent the hydrogen generated later from combining with oxygen to generate an explosion risk.

[0089] Preferably, in some implementations, step S100 includes:

[0090] S101, classifying the secondary aluminum ash;

[0091] Specifically, the classification process can be performed by screening or cyclone classification, but is not limited thereto. Preferably, in one embodiment, the classification process is performed by cyclone classification.

[0092] The 125 μm sieve residue of the secondary aluminum ash obtained after classification is 1-10 wt%, preferably 1-5 wt%. The hydrolysis reaction is carried out by using the part with a particle size less than 125 μm, which significantly increases the hydrolysis reaction rate and reduces the content of metal aluminum and aluminum nitride in the residue after hydrolysis.

[0093] It should be noted that in the conventional treatment of secondary aluminum ash, in order to enhance the reaction activity, the secondary aluminum ash is generally first ground, which consumes a lot of energy. However, the comprehensive utilization method based on the present invention does not require a grinding process, which greatly reduces energy consumption.

[0094] S102, deoxidize the secondary aluminum ash by nitrogen replacement.

[0095] S200, hydrolyzing the deoxidized secondary aluminum ash, and performing solid-liquid separation to obtain a mixed gas, a hydrolysis slurry solid phase, and a high-salinity alkali ammonia nitrogen hydrolyzate;

[0096] Preferably, in one embodiment, secondary aluminum ash is mixed with water at a solid-liquid ratio of 1:(2-10) and added to a reactor. The water may be pure water, water obtained from a subsequent hydrolysis slurry solid phase treatment process, or cooling water, but is not limited thereto. Preferably, the solid-liquid ratio is 1:3-1:6. More specifically, about 1 / 3 of the total water volume is first added to the reactor, then the deoxidized secondary aluminum ash is added, and then the remaining water is added.

[0097] At the beginning of hydrolysis, calcium hydroxide and a catalyst are added to the reactor. Specifically, the weight ratio of calcium hydroxide to the deoxidized secondary aluminum ash is (1-10):100 to achieve a supersaturated state, so that the pH of the reaction liquid in the reactor reaches 12-13. Specifically, the weight ratio of the catalyst to the deoxidized secondary aluminum ash is (1-10):100; preferably 3:100-8:100.

[0098] Preferably, in one embodiment, the catalyst includes, by weight: 0-10 parts of sodium carbonate, 0-10 parts of potassium carbonate, 10-80 parts of sodium hydroxide, 0-50 parts of potassium hydroxide, 5-30 parts of calcium carbide slag, and 0.01-5 parts of sodium stannate. Based on the catalyst, more aluminum nitride and aluminum can be hydrolyzed at a lower temperature (5-99° C.) and in a shorter time (5-48 hours).

[0099] Specifically, the temperature of the hydrolysis reaction is 5-99° C., preferably 80-90° C. The time of the hydrolysis reaction is 5-48 hours, preferably 5-24 hours. Based on this reaction condition, the elemental aluminum and aluminum nitride in the secondary aluminum ash can be almost completely removed.

[0100] It should be noted that the hydrolysis reaction of secondary aluminum ash and water can be divided into an induction period, an acceleration period and a deceleration period. In the induction period of the hydrolysis reaction, that is, within about 0.5-1h after the start of the hydrolysis reaction, the speed of the hydrolysis reaction is slow and there is no obvious heat release. In the acceleration period of the hydrolysis reaction, that is, about 0.5-1h after the start of the hydrolysis reaction, the reaction speed is accelerated, accompanied by obvious heat release. In the deceleration period of the hydrolysis reaction, the reaction speed and the heat release rate slow down. Therefore, in the acceleration period, the internal temperature of the reactor will exceed the boiling point of water (100°C at normal pressure) within a few hours after the start of the hydrolysis reaction. A large amount of water vapor enters the gas phase, which will bring difficulties to the subsequent hydrogen purification. And the rapid rise in temperature will also produce a large amount of foam, making the reaction difficult to control. In the deceleration period of the hydrolysis reaction, the internal temperature of the reactor begins to drop, and the hydrolysis reaction speed begins to drop significantly. To this end, the present invention controls the temperature of the hydrolysis reaction to less than 100°C, preferably controlled at 5-99°C, and more preferably controlled to 80-90°C.

[0101] In order to achieve the above-mentioned temperature control, in one embodiment, the temperature during the hydrolysis process is carried out according to the following procedure:

[0102] Add secondary aluminum ash, water, catalyst and calcium hydroxide into the reactor. When the temperature in the reactor rises to 70-90°C, use cooling medium to cool the reactor so that the temperature rise rate in the reactor is controlled to be 0.1-3°C / min. Specifically, the cooling medium can be water, but is not limited thereto.

[0103] When the temperature rise rate in the reactor decreases, gradually reduce the amount of cooling medium to maintain the temperature in the reactor at 80-90°C;

[0104] When the temperature in the reactor starts to drop, heating medium is used for heating, and the amount of heating medium is adjusted to maintain the temperature in the reactor at 80-90° C., wherein the difference between the temperature of the heating medium and the temperature in the reactor is 1-10° C. Specifically, the heating medium may be hot water, but is not limited thereto.

[0105] Accordingly, in order to achieve the above temperature control, the structure of the reactor is also modified. It is also necessary to set an inner coil, an outer coil or a jacket on the conventional reactor to pass the cooling medium or the heating medium.

[0106] S300, separating and purifying the mixed gas to obtain hydrogen;

[0107] Specifically, during the hydrolysis reaction, the generated gas is collected to obtain a mixed gas. The specific processing flow of the mixed gas is as follows: water is used as the water-absorbing gas, multi-stage absorption is performed, NH3 in the mixed gas is absorbed, and hydrogen is purified by pressure swing adsorption (PSA) to a purity of more than 99.99wt%. The impurity gas (CH4, H3P, H2S, etc.) of the pressure swing adsorption is sent to a regenerative thermal incinerator (RTO) for incineration to provide heat energy to heat water. The heated water can be used as a heating medium to heat the reactor during the deceleration period of the hydrolysis reaction. Specifically, the temperature of the heated water is 81-99°C.

[0108] Specifically, after the hydrolysis treatment is completed, the obtained slurry is subjected to solid-liquid separation to obtain a hydrolysis slurry solid phase and a high-salinity alkali ammonia nitrogen hydrolyzate. The water content of the hydrolysis slurry solid phase is 15-25wt%, and it contains heavy metals such as Pb, Cd, Cr, Cu, Ni, Zn, Mn, and Cl - 、F - , K + 、Na + Preferably, the temperature of the high-salinity alkali ammonia nitrogen hydrolyzate is 80-95°C, the alkalinity is 0.20-2.0 mol / L, the total salt content is 5-25%, and the ammonia nitrogen concentration is 200-2000 mg / L. More preferably, the temperature of the high-salinity alkali ammonia nitrogen hydrolyzate is 85-90°C, the alkalinity is 0.25-1.5 mol / L, the total salt content is 10-20%, and the ammonia nitrogen concentration is 200-2000 mg / L.

[0109] S400, subjecting the hydrolyzed slurry solid phase to at least two acid washing treatments and at least one alkali washing treatment to obtain a solid phase product for concrete admixture;

[0110] Preferably, in one embodiment: step S400 includes:

[0111] The hydrolyzed slurry solid phase is subjected to at least two acid washing treatments, and the slurry obtained by the acid washing treatment is subjected to solid-liquid separation to obtain a sub-solid phase and a first sub-liquid phase; the sub-liquid phase is used for the secondary aluminum ash hydrolysis treatment or the last acid washing treatment;

[0112] The sub-solid phase is subjected to at least one alkali washing treatment, and the slurry obtained by the alkali washing treatment is subjected to solid-liquid separation to obtain a solid phase product and a second sub-liquid phase, and the second sub-liquid phase is used for acid washing treatment;

[0113] The content of tracer ions is measured in the slurry after both the acid washing treatment and the alkali washing treatment, and the tracer ions are heavy metals and / or impurity ions.

[0114] In the process of treating the solid phase of the hydrolyzed slurry, the present invention washes it multiple times, separates the solid and the liquid after each washing, and the obtained liquid is recycled in the hydrolysis process or the washing process, and the obtained solid is used in concrete, and the heavy metals and impurity ions are monitored during each washing process. Based on this process, not only the water consumption is effectively reduced, but also the elution efficiency of heavy metals and impurity ions is improved, which is conducive to the high added value utilization of the hydrolyzed slurry solid phase.

[0115] It should be noted that the multiple washings of the present invention may be two washings or three or more washings, preferably 3-5 times, and the number of washings may be determined according to the actual situation of the secondary aluminum ash.

[0116] It should be noted that in order to improve the treatment efficiency of the hydrolyzed mud solid phase, a washing kettle with a specific structure is used for washing. Figure 2 and Figure 3 The washing kettle comprises a washing kettle body 100, wherein the washing kettle body 100 comprises a kettle body 10, a feeding port 20 and a water inlet 30 arranged at the upper part of the kettle body 10, a discharge valve 40 and a mud pump 50 arranged at the lower part of the kettle body 10, an ultrasonic and spoiler plate 60, an agitator 70 and an aeration pipe 80 arranged inside the kettle body 10, and a power unit 90 for controlling the rotation of the agitator, wherein the power unit 90 comprises a motor 91 and a reducer 92;

[0117] The ultrasonic and spoiler plate 60 is arranged on the inner wall of the kettle body, and is used to make the slurry in the kettle body 10 vibrate and generate eddy currents to improve the cleaning efficiency. The ultrasonic and spoiler plate 60 is controlled to generate ultrasonic waves in the range of 20-80kHz for vibration, and preferably in the range of 30-50kHz. The ultrasonic wave provides oscillation of the liquid phase, and the spoiler plate forms eddy currents inside the washing kettle, and the two together improve the washing efficiency and significantly improve the elution efficiency of heavy metals and impurity ions.

[0118] In addition, the ultrasonic stirrer 4 is controlled so as to generate a vortex flow in a direction opposite to the rotation direction of the stirring blade 5 .

[0119] The aeration pipe 80 is arranged at the bottom of the kettle body, and includes an aeration main pipe 81 and an annular aeration pipe 82. The annular aeration pipe 82 includes a plurality of concentrically arranged annular aeration sub-pipes, and the plurality of annular aeration sub-pipes are connected to the aeration main pipe 81. The annular aeration pipe 82 is arranged at the bottom of the kettle body, and is made of porous ceramics for ejecting carbon dioxide.

[0120] Specifically, in one embodiment, step S400 includes:

[0121] S401, injecting a first washing liquid into the first washing kettle, and sending the hydrolyzed mud solid phase into it for washing, wherein the first washing liquid comes from the second liquid phase after the mud is filtered out of the second washing kettle outlet;

[0122] Preferably, the agitator and the ultrasonic generator are turned on for washing, wherein the agitator rotates at 20-80 r / min, preferably 40-60 r / min, and the ultrasonic frequency is 20-80 kHz, preferably 30-50 kHz.

[0123] Preferably, the solid-liquid ratio (mass ratio) in the first-stage washing kettle is set to 1:(3-10), and the first washing liquid is injected into the first-stage washing kettle, and the liquid level reaches 50-80% of the internal height of the washing kettle. The first washing liquid comes from the second liquid phase after the mud is filtered out at the outlet of the second-stage washing kettle.

[0124] The hydrolyzed sludge solid phase after filter pressing is put into the first-stage washing kettle, and the amount of the solid phase is determined according to the amount of washing liquid and the predetermined liquid-solid ratio.

[0125] S402, introducing a first gas into the primary washing kettle until the pH value of the washing liquid reaches a first preset value.

[0126] Preferably, the first gas is CO2, and CO2 is introduced into the primary washing kettle until the pH of the washing liquid is 6-7.

[0127] The present invention first introduces CO2, which is converted into carbonate, and performs the first pH adjustment. The pH is controlled at 6-7, which can dissolve heavy metals and impurity ions in the liquid phase to a greater extent, thereby improving the elution efficiency of heavy metals and impurity ions. In addition, CO2 is used as a pH regulator and converted into carbonate, thereby realizing a negative carbon process.

[0128] S403, introducing an acidic solution into the primary washing kettle until the pH of the washing solution reaches a second preset value;

[0129] Preferably, the acidic solution is one or a combination of sulfuric acid, nitric acid, and organic acid, and the second preset value of pH is 2-6, but not limited thereto. In the present invention, after the first gas is introduced, the acidic solution is introduced into the primary washing kettle to adjust the pH to 2-6, so that heavy metals and impurity ions can be dissolved in the liquid phase to a greater extent.

[0130] The temperature of the first-stage washing kettle is preferably controlled at 15-40° C., more preferably 20-35° C. After the acid solution is introduced, washing begins, and the washing time is preferably 5-50 min, more preferably 5-30 min.

[0131] It should be noted that the washing time is determined according to the concentration change rate of heavy metals and impurity ions in the liquid phase.

[0132] S403 The washing end judgment condition is: detect the tracer ion, and when the change of the tracer ion content between two adjacent times is less than the ion preset value, the washing ends.

[0133] In this step, one or more heavy metal or impurity ions can be selected as tracer ions, and samples can be taken at preset intervals; the content of the tracer ions is detected, and if the change in the tracer ion content between two adjacent times is less than the preset value of the ion, the washing is finished. The preset interval time is 5-20 minutes, preferably 5-10 minutes; the preset value of the ion is 5-10%, preferably 5-8%.

[0134] Specifically, the heavy metals used as tracer ions include one or more of Pb, Cd, Cr, Cu, Ni, Zn, and Mn, and the impurity ions used as tracer ions include Cl - 、F - , K + 、Na + One or more of .

[0135] S404, after the washing of the first washing kettle is completed, the slurry is subjected to solid-liquid separation to obtain a first liquid phase and a first solid phase, wherein the first liquid phase can be used for secondary aluminum ash hydrolysis treatment;

[0136] Preferably, after washing is completed, the mud in the first washing kettle is pumped into a filter press for solid-liquid separation. The solid phase after filter pressing contains about 15-25% water. The first solid phase enters the second washing kettle for further washing, and the first liquid phase is used for secondary aluminum ash hydrolysis treatment, which effectively reduces water consumption and improves the elution efficiency of heavy metals and impurity ions.

[0137] S405, injecting a second washing liquid into the secondary washing kettle, and sending the first solid phase into the washing kettle for further washing, wherein the second washing liquid comes from the third liquid phase after the mud is filtered out at the outlet of the tertiary washing kettle;

[0138] Preferably, the agitator and the ultrasonic generator are turned on for washing, wherein the agitator rotates at 20-80 r / min, preferably 40-60 r / min, and the ultrasonic frequency is 20-80 kHz, preferably 30-50 kHz.

[0139] Preferably, the solid-liquid ratio (mass ratio) in the secondary washing kettle is set to 1:(3-10), and the second washing liquid is injected into the secondary washing kettle, and the liquid level reaches 50-80% of the internal height of the washing kettle. The second washing liquid comes from the third liquid phase after the mud is filtered out of the tertiary washing kettle outlet.

[0140] The first solid phase is placed into the secondary washing kettle, and the amount of the solid phase is determined according to the amount of washing liquid and the predetermined liquid-solid ratio.

[0141] S406, introducing an acidic solution into the secondary washing kettle until the pH of the washing solution reaches a second preset value;

[0142] Preferably, the acidic solution is one or a combination of sulfuric acid, nitric acid, and organic acid, and the second preset value of pH is 2-6, but not limited thereto. In the present invention, after the primary washing, the acidic solution is introduced into the secondary washing kettle to adjust the pH to 2-6, so that heavy metals and impurity ions can be dissolved in the liquid phase to a greater extent.

[0143] The temperature of the secondary washing kettle is preferably controlled at 15-40°C, more preferably 20-35°C.

[0144] After the acid solution is introduced, washing begins, and the washing time is preferably 5-50 min, more preferably 5-30 min.

[0145] It should be noted that the washing time is determined according to the concentration change rate of heavy metals and impurity ions in the liquid phase.

[0146] S406 The washing end judgment condition is: detect the tracer ion, and when the change of the tracer ion content between two adjacent times is less than the ion preset value, the washing ends.

[0147] In this step, one or more heavy metal or impurity ions can be selected as tracer ions, and samples can be taken at preset intervals; the content of the tracer ions is detected, and if the change in the tracer ion content between two adjacent times is less than the preset value of the ion, the washing is finished. The preset interval time is 5-20 minutes, preferably 5-10 minutes; the preset value of the ion is 5-10%, preferably 5-8%.

[0148] Specifically, the heavy metals used as tracer ions include one or more of Pb, Cd, Cr, Cu, Ni, Zn, and Mn, and the impurity ions used as tracer ions include Cl - 、F - , K + 、Na + One or more of .

[0149] S407, after the washing in the secondary washing kettle is completed, the slurry is subjected to solid-liquid separation to obtain a second liquid phase and a second solid phase;

[0150] Preferably, after washing is completed, the mud in the secondary washing kettle is pumped into a filter press for solid-liquid separation. The solid phase after filtration contains about 15-25% water. The second solid phase enters the tertiary washing kettle for further washing. The second liquid phase is used to wash the hydrolyzed mud solid phase in the primary washing kettle, which effectively reduces the water consumption and improves the elution efficiency of heavy metals and impurity ions.

[0151] S408, injecting a third washing liquid into the third-stage washing kettle, and sending the second solid phase into the kettle for washing, wherein the third washing liquid is water;

[0152] Preferably, the agitator and the ultrasonic generator are turned on for washing, wherein the agitator rotates at 20-80 r / min, preferably 40-60 r / min, and the ultrasonic frequency is 20-80 kHz, preferably 30-50 kHz.

[0153] Preferably, the solid-liquid ratio (mass ratio) in the tertiary washing kettle is set to 1:(3-10), and the third washing liquid is injected into the tertiary washing kettle, and the liquid level reaches 50-80% of the internal height of the washing kettle. The third washing liquid is water.

[0154] The second solid phase is added to the tertiary washing kettle, and the amount of the solid phase is determined according to the amount of washing liquid and the predetermined liquid-solid ratio.

[0155] S409, introducing alkaline substances into the third-stage washing kettle until the pH of the washing liquid reaches a third preset value;

[0156] Preferably, the alkaline substance is one or a combination of calcium hydroxide, sodium hydroxide, and carbide slag, and the second preset value of pH is 7-12, preferably 8-11, but not limited thereto. In the present invention, after the secondary washing, the alkaline substance is introduced into the tertiary washing kettle, which can dissolve heavy metals and impurity ions in the liquid phase to a greater extent, and can react a small amount of residual or wrapped aluminum element, aluminum nitride, etc. Among them, the temperature of the tertiary washing kettle is preferably controlled at 15-40°C, more preferably 20-35°C.

[0157] After the alkaline substance is introduced, washing begins, and the washing time is preferably 5-50 minutes, more preferably 5-30 minutes.

[0158] It should be noted that the washing time is determined according to the concentration change rate of heavy metals and impurity ions in the liquid phase.

[0159] S409 The washing end judgment condition is: detect the tracer ion, and when the change of the tracer ion content between two adjacent times is less than the ion preset value, the washing ends.

[0160] In this step, one or more heavy metal or impurity ions can be selected as tracer ions, and samples can be taken at preset intervals; the content of the tracer ions is detected, and if the change in the tracer ion content between two adjacent times is less than the preset value of the ion, the washing is finished. The preset interval time is 5-20 minutes, preferably 5-10 minutes; the preset value of the ion is 5-10%, preferably 5-8%.

[0161] Specifically, the heavy metals used as tracer ions include one or more of Pb, Cd, Cr, Cu, Ni, Zn, and Mn, and the impurity ions used as tracer ions include Cl - 、F - , K + 、Na + One or more of .

[0162] S410, after the washing of the three-stage washing kettle is completed, the slurry is subjected to solid-liquid separation to obtain a third liquid phase and a third solid phase;

[0163] Preferably, after washing is completed, the mud in the tertiary washing kettle is pumped into a filter press for solid-liquid separation. The solid phase after filtration contains about 15-25% water. The third liquid phase is used to wash the solid phase in the secondary washing kettle, which effectively reduces the water consumption and improves the elution efficiency of heavy metals and impurity ions.

[0164] S411, detecting the content of heavy metals and impurity ions in the third solid phase, if it meets the prescribed standard, washing is completed, if it does not meet the prescribed standard, repeating the washing of the three-stage washing kettle.

[0165] S500, separating ammonia nitrogen from the high-salinity alkaline ammonia nitrogen hydrolyzate, and performing a stepwise acidification treatment to obtain aluminum hydroxide and inorganic salt crystals.

[0166] It should be noted that steps S400, S500, and S600 can be executed in no particular order and can be executed simultaneously, or one or two of them can be executed first and then the remaining steps.

[0167] Preferably, in an embodiment of the present invention, step S500 includes:

[0168] S501, separating ammonia nitrogen from the high-salinity alkaline ammonia nitrogen hydrolyzate to obtain a gas phase and a first-stage liquid phase;

[0169] Preferably, in step S501, the high-salinity alkaline ammonia nitrogen hydrolyzate is aerated by passing air to obtain a gas phase and a first-stage liquid phase, and the gas phase is dissolved in water to obtain ammonia water.

[0170] More preferably, the high-salinity alkaline ammonia nitrogen hydrolyzate is introduced into a reactor, the speed of the reactor is set to 40-150r / min, and air is introduced for aeration, with an air flow rate of 10-30m 3 / min, reaction time 0.5-3h, the obtained ammonia gas is passed into an absorption tower to obtain ammonia water.

[0171] The present invention uses air aeration to drive away ammonia in the high-salinity alkali ammonia nitrogen hydrolyzate, and can break its buffer system to prepare for subsequent pH adjustment. Moreover, the obtained ammonia is used in the subsequent stripping process to achieve the purpose of resource recycling. Furthermore, air aeration is used to oxidize pollutants such as reducing sulfide or thiosulfate in the high-salinity alkali ammonia nitrogen hydrolyzate into sulfate, thereby increasing the purity of the subsequent sulfate.

[0172] S502, dissolving carbon dioxide in the first-stage liquid phase until a specified pH value is reached to obtain a second-stage liquid phase;

[0173] Preferably, carbon dioxide is dissolved in the first-stage liquid phase until a specified pH value is reached, and the first-stage liquid phase is subjected to aluminum hydroxide separation to obtain aluminum hydroxide and a second-stage liquid phase.

[0174] More preferably, carbon dioxide is introduced into the first-stage liquid phase, the carbon dioxide flow rate is set to 1000-3000 mL / min, the rotation speed is set to 30-150 r / min, the reaction is stopped when the reaction pH drops from 12-14 to 7-8, the slurry is separated into solid and liquid to obtain aluminum hydroxide and the second-stage liquid phase.

[0175] S503, dissolving carbon dioxide in the second-level liquid phase until a specified pH value is reached to obtain a third-level liquid phase;

[0176] Preferably, carbon dioxide is dissolved in the second-stage liquid phase until a specified pH value is reached, and the second-stage liquid phase is subjected to sodium bicarbonate separation to obtain sodium bicarbonate and a third-stage liquid phase.

[0177] More preferably, the second liquid phase is transferred to a reactor, carbon dioxide is introduced into the reactor, the carbon dioxide flow rate is set to 1000-3000 mL / min, the rotation speed is set to 40-150 r / min, the reaction pH is reduced from 7-8 to 5-6 to stop the reaction, and the slurry is separated into solid and liquid to obtain sodium bicarbonate and the third liquid phase.

[0178] This step can achieve the following goals by adjusting the pH with carbon dioxide: first, aluminate can be precipitated into aluminum hydroxide; second, the amount of treated water does not need to be increased; and third, the alkali production principle can be used to produce high-valent salt sodium bicarbonate in a high-salt alkali system.

[0179] Aluminum hydroxide can be washed with water with a small amount of sodium bicarbonate crystals attached to it. The resulting sodium bicarbonate washing solution can be added with subsequent sodium chloride to saturate the solution and precipitate sodium bicarbonate crystals, thereby achieving the effect of resource recycling.

[0180] S504, adding an extraction solvent to the third liquid phase and dissolving carbon dioxide until a specified pH value is reached, and obtaining a fourth liquid phase of an organic phase and a fourth liquid phase of an inorganic phase after extraction and separation;

[0181] Preferably, an extraction solvent is added to the third liquid phase and carbon dioxide is dissolved until a specified pH value is reached, chlorine is extracted and separated, and then a fourth liquid phase of an organic phase and a fourth liquid phase of an inorganic phase are obtained.

[0182] Further preferably, the third liquid phase is transferred to a reactor, carbon dioxide is introduced into the reactor, and an extraction solvent is added at the same time, and the volume ratio of the organic phase (i.e., the extraction solvent): the inorganic phase (i.e., the third liquid phase) is set to (1-2): (2-3), and the solubility of carbon dioxide is set to 0.05-0.08 mol / L. The reaction is stopped when the reaction pH drops from 5-6 to 3-4, and the fourth liquid phase of the organic phase and the fourth liquid phase of the inorganic phase are obtained after extraction and separation.

[0183] More preferably, the third liquid phase is transferred to a reactor, and carbon dioxide is introduced into the reactor at a flow rate of 1000-3000 mL / min. An extraction solvent is added at the same time, and the volume ratio of the organic phase:inorganic phase is set to (1-2):(2-3) so that the solubility of carbon dioxide is 0.06-0.07 mol / L. The speed of the reactor is set to 40-150 r / min, the reaction temperature is 20-25°C, and the reaction pressure is 1-3 MPa. The reaction is stopped when the pH value of the reaction drops from 5-5.5 to 3-3.5, and the fourth liquid phase of the organic phase and the fourth liquid phase of the inorganic phase are obtained after extraction and separation.

[0184] More preferably, the third liquid phase is transferred to a reactor, and carbon dioxide is introduced into the reactor at a flow rate of 1000-2000 mL / min. An extraction solvent is added at the same time, and the volume ratio of the organic phase: inorganic phase is set to 1:2, so that the solubility of carbon dioxide is 0.06-0.07 mol / L, the speed of the reactor is set to 40-150 r / min, the reaction temperature is 20-25°C, and the reaction pressure is 1-3Mpa. The reaction is stopped when the reaction pH drops from 5 to about 3, and the fourth liquid phase of the organic phase and the fourth liquid phase of the inorganic phase are obtained after extraction and separation.

[0185] The extraction solvent comprises an extractant and a diluent, wherein the extractant is preferably one or more of alkyl primary amines, secondary amines, trioctyl tertiary amines, and trioctyl methyl quaternary ammonium salts, but is not limited thereto; the diluent is preferably one or more of kerosene, tributyl phosphate, n-pentanol, n-hexanol, n-octanol, and isooctyl alcohol, but is not limited thereto.

[0186] It should be noted that the extraction solvent of the present invention can be selected according to actual needs.

[0187] In this step, carbon dioxide is introduced and an extraction solvent is added for extraction and separation, so that chlorine can be extracted and separated efficiently. The extraction principle of chloride ions is as follows:

[0188]

[0189] Among them, R3N is the extractant, H + Provided by pressurized carbon dioxide, C l - Provided by chloride ions in the liquid phase.

[0190] The present invention continues to use pressurized carbon dioxide plus extraction method to extract chlorine, so as to obtain ammonium chloride. The obtained ammonium chloride has high purity, and the extractant can be recycled after back extraction.

[0191] S505, evaporating the water in the fourth liquid phase of the inorganic phase.

[0192] Preferably, the fourth liquid phase of the inorganic phase is subjected to MVR separation to evaporate water to obtain sodium chloride and sodium sulfate.

[0193] Further preferably, the fourth-stage liquid phase of the inorganic phase is discharged from the bottom of the reactor and heated to 90-100° C., and then pumped into the MVR evaporator, and the compressor is started to produce sodium sulfate and mother liquor when the sodium sulfate is supersaturated;

[0194] When the sodium sulfate concentration of the mother liquor is reduced to 3-7% and the temperature is reduced to 45-55°C, the mother liquor is transported to the MVR evaporator, the compressor is turned on, and sodium chloride is obtained after supersaturation concentration.

[0195] More preferably, step S106 includes:

[0196] The fourth-level liquid phase of the inorganic phase is discharged from the bottom of the reactor and heated to 90-100°C, then pumped into the MVR evaporator, and the compressor is started. When the sodium sulfate is supersaturated, sodium sulfate and mother liquor are produced;

[0197] When the sodium sulfate concentration of the mother liquor is reduced to 4-6% and the temperature is reduced to 50-55°C, the mother liquor is transported to the MVR evaporator, the compressor is turned on, and sodium chloride is obtained after supersaturation.

[0198] In this step, high-quality sodium chloride and sodium sulfate can be obtained through MVR separation, with high yield and high purity.

[0199] S506, performing back extraction separation on the fourth-level liquid phase of the organic phase to obtain an inorganic liquid phase and an organic liquid phase, evaporating the water in the inorganic liquid phase, and returning the organic liquid phase to the treatment of the third-level liquid phase.

[0200] Preferably, aqueous ammonia is added to the fourth liquid phase of the organic phase for back extraction separation to obtain an inorganic liquid phase and an organic liquid phase, wherein the water in the inorganic liquid phase is evaporated to obtain ammonium chloride; and the organic liquid phase is returned to the treatment of the third liquid phase.

[0201] Further preferably, when adding ammonia water to the fourth liquid phase of the organic phase for back extraction separation, the volume ratio of organic phase: inorganic phase is set to (1-2): (0.5-1), and the rotation speed is 40-150r / min. It should be noted that the organic phase here refers to the fourth liquid phase of the organic phase, and the inorganic phase refers to the added extract (such as ammonia water, etc.).

[0202] More preferably, ammonia water is added to the fourth liquid phase of the organic phase, the volume ratio of the organic phase: the inorganic phase (ammonia water) is set to 1:0.5, and the rotation speed is set to 40-150r / min for back extraction separation to obtain an inorganic liquid phase and an organic liquid phase, wherein the fourth liquid phase of the organic phase is reused in the treatment of the third liquid phase in step S504 to evaporate the water in the inorganic liquid phase to obtain ammonium chloride.

[0203] It should be noted that the ammonia water added here may be the ammonia water obtained in step S501.

[0204] After the third-level liquid phase extraction and separation, the fourth-level liquid phase of the organic phase and the fourth-level liquid phase of the inorganic phase are obtained. The fourth-level liquid phase of the inorganic phase contains a small amount of sulfate and chloride. The present invention realizes zero wastewater discharge through MVR evaporation, and the fourth-level liquid phase of the organic phase is added with ammonia water for back extraction and separation to obtain ammonium chloride.

[0205] The present invention is further described below with specific embodiments.

[0206] Example 1

[0207] This embodiment provides a comprehensive utilization method of secondary aluminum ash, and the following three parts are respectively given specific implementation methods:

[0208] (I) Hydrolysis reaction and treatment of mixed gas

[0209] 1. Powder selection: The secondary aluminum ash is classified by a powder selection machine. After classification, the 125μm sieve residue of the secondary aluminum ash is 3.5%;

[0210] 2. Deoxidation: Place the secondary aluminum ash in a reactor, introduce nitrogen for replacement, and perform deoxidation treatment;

[0211] 3. Hydrolysis: feed materials according to the solid-liquid ratio of 1:3.5, first add about 1 / 3 of the total water into the reactor, add the secondary aluminum ash after deoxidation treatment, then add the remaining water, and then add calcium hydroxide until the pH of the reaction solution is 12.5, and at the same time add 3wt% of the weight of the secondary aluminum ash catalyst to start the reaction. The catalyst formula is: 10 parts of sodium carbonate, 20 parts of sodium hydroxide, 10 parts of calcium carbide slag, and 0.03 parts of sodium stannate.

[0212] The initial reaction temperature is 15°C and the pressure is normal pressure. When the temperature inside the reactor reaches 75°C, cooling water is introduced into the inner coil of the reactor, and the flow rate of the cooling water is controlled to control the temperature rise rate inside the reactor at 1.2°C / min. When the temperature rise rate of the reactor begins to decrease, the cooling water flow rate is gradually reduced until it is completely closed. After closing, the temperature inside the reactor is about 87°C. When the temperature inside the reactor begins to drop, hot water is introduced into the jacket. The hot water comes from a regenerative thermal incinerator. The temperature of the hot water is 91°C. The flow rate of the hot water entering the jacket is adjusted to keep the temperature inside the reactor at around 88°C.

[0213] 4. Gas collection and purification: The hydrolysis reaction time is 22 hours. During the hydrolysis process, the gas discharged from the reactor is collected, and a multi-stage absorption tower is used to absorb, separate and dry the mixed gas with NH3 as the main component. The gas absorbed by the multi-stage absorption tower is mainly hydrogen. The absorption liquid of the multi-stage absorption tower is clean water. The absorption liquid with ammonia as the main component out of the absorption tower is further utilized.

[0214] The gas separated by the multi-stage absorption tower is mainly hydrogen. The hydrogen is purified by pressure swing adsorption. The purity (mass fraction) of the purified hydrogen is 99.995%. The impurity gas of pressure swing adsorption enters the regenerative thermal incinerator (RTO) for incineration. The heat energy is used to heat the cooling water (inner coil) from the reactor. The heated hot water is used to keep the reactor warm. The water temperature after heating is 93℃.

[0215] 5. Collection and separation of liquid phase and solid phase: The slurry obtained after the hydrolysis reaction is subjected to solid-liquid separation to obtain hydrolyzed mud solid phase and high-salinity alkali ammonia nitrogen hydrolyzate, wherein the high-salinity alkali ammonia nitrogen hydrolyzate has a hydroxide concentration of 0.6 mol / L, an aluminum ion concentration of 15 g / L, a total salinity of 12%, a chloride ion concentration of 27.7 g / L, an ammonia nitrogen concentration of 2000 mg / L, and sulfide and thiosulfate concentrations of 1.98 g / L and 13.5 g / L. The water content of the hydrolyzed mud solid phase is 18 wt%.

[0216] (II) Treatment of high-salinity alkaline ammonia nitrogen hydrolyzate

[0217] 1. Separate the high-salinity alkaline ammonia nitrogen hydrolyzate to obtain gaseous ammonia and the first-level liquid phase, and dissolve the gaseous ammonia in water to obtain ammonia water;

[0218] The high-salinity alkaline ammonia nitrogen hydrolyzate is separated from the ammonia nitrogen in the reactor. The speed of the reactor is set at 40r / min, and air is introduced for aeration. The air flow rate is 10 3 / min, reaction time 1h.

[0219] 2. Dissolving carbon dioxide in the first liquid phase until a specified pH value is reached to obtain a second liquid phase;

[0220] Among them, carbon dioxide was introduced, the carbon dioxide flow rate was set to 1000mL / min, the rotation speed was set to 40r / min, the reaction was stopped when the reaction pH dropped from 14 to about 7, and the slurry was transferred to a belt filter press for solid-liquid separation to obtain aluminum hydroxide and a second liquid phase.

[0221] 3. Dissolving carbon dioxide in the second-stage liquid phase until a specified pH value is reached to obtain a third-stage liquid phase;

[0222] Among them, the second-stage liquid phase is transferred to the reactor, and carbon dioxide is introduced into the reactor. The carbon dioxide flow rate is set to 1200mL / min, and the rotation speed is set to 40r / min. The reaction is stopped when the reaction pH drops from 7 to about 6. The slurry is transferred to a plate and frame filter press for solid-liquid separation to obtain sodium bicarbonate and the third-stage liquid phase.

[0223] 4. Adding an extraction solvent to the third liquid phase and dissolving carbon dioxide until a specified pH value is reached, and obtaining a fourth liquid phase of an organic phase and a fourth liquid phase of an inorganic phase after extraction and separation;

[0224] Among them, the third liquid phase is transferred to the reactor, carbon dioxide is introduced into the reactor, the rotation speed is set to 40r / min, the flow rate of carbon dioxide is 1100mL / min, and the extraction solvent (extractant alkyl primary amine + diluent kerosene) is added at the same time, and the volume ratio of organic phase: inorganic phase is set to 1:2. The reaction temperature of the reactor is 20°C, the reaction pressure is 1.85Mpa, and the solubility of carbon dioxide is 0.07mol / L. The reaction pH is reduced from 6 to about 3 to stop the reaction, and the fourth liquid phase of the organic phase and the fourth liquid phase of the inorganic phase are obtained after extraction and separation.

[0225] 5. Evaporating the water in the fourth liquid phase of the inorganic phase;

[0226] Among them, the solution is discharged from the bottom of the reactor, heated to 100°C, and then pumped into the MVR crystallization evaporator, the compressor is started, and sodium sulfate and mother liquor are produced when the sodium sulfate concentration of the mother liquor is reduced to 5%, the temperature is reduced to 50°C, the mother liquor is transported to the MVR evaporator, the compressor is turned on, and sodium chloride is obtained after supersaturation concentration.

[0227] 6. Perform back extraction separation on the fourth-stage liquid phase of the organic phase to obtain an inorganic liquid phase and an organic liquid phase, evaporate the water in the inorganic liquid phase, and return the organic liquid phase to the treatment of the third-stage liquid phase.

[0228] Wherein, after the fourth level liquid phase of the inorganic phase is separated in step 4, part of the ammonia water in step 1 is added to the fourth level liquid phase of the organic phase, the volume ratio of the organic phase: the inorganic phase is set to about 1:0.5, the rotation speed is set to 40r / min, and the back extraction separation is performed to obtain the fourth level liquid phase of the organic phase and reuse it in step 4, and the fourth level liquid phase of the inorganic phase is concentrated and evaporated to obtain ammonium chloride.

[0229] After the high-salinity alkaline ammonia nitrogen hydrolyzate was treated in this embodiment, the yields of the obtained products were as follows:

[0230]

[0231]

[0232] (III) Treatment of solid phase of hydrolyzed mud

[0233] The solid-liquid ratio (mass ratio) in each washing tank is set to 1:3.4, and the first washing liquid is injected into the first washing tank, and the liquid level reaches 55% of the internal height of the washing tank. The first washing liquid comes from the second liquid phase after the mud is filtered out of the outlet of the second washing tank.

[0234] The hydrolyzed sludge solid phase after filter pressing is put into the first-stage washing kettle, and the amount of the solid phase is determined according to the amount of washing liquid and the predetermined liquid-solid ratio.

[0235] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 55r / min, and the ultrasonic frequency is 40kHz.

[0236] Introduce CO2 into the primary washing kettle until the pH of the washing liquid reaches 6.5.

[0237] Nitric acid is introduced into the primary washing kettle until the pH of the washing liquid reaches 3.

[0238] Start washing, the washing time is 18min. Select chloride ion (Cl - ) as the tracer ion, sampling was performed at 5-minute intervals to test the tracer ion content. When the change in chloride ion content between two times was less than 10%, the washing was completed.

[0239] After washing, the mud in the first-stage washing kettle is pumped into the filter press for solid-liquid separation. The first solid phase enters the second-stage washing kettle for further washing, and the first liquid phase is used for secondary aluminum ash hydrolysis.

[0240] The second washing liquid is injected into the secondary washing kettle, and the liquid level reaches 55% of the internal height of the washing kettle. The washing liquid of the secondary washing kettle comes from the third liquid phase after the mud is pressed and filtered at the outlet of the tertiary washing kettle.

[0241] The first solid phase after filter pressing is placed into the secondary washing kettle, and the amount of the first solid phase is determined according to a predetermined liquid-solid ratio.

[0242] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 55r / min, and the ultrasonic frequency is 40kHz.

[0243] Nitric acid was introduced into the washing kettle until the pH of the washing liquid reached 2.

[0244] Start washing, the washing time is 22min. Select chloride ion (Cl - ) as a tracer ion, sampling is carried out at an interval of 5 minutes to check the chloride ion content. When the change of the tracer ion content between two adjacent times is less than 10%, the washing is completed.

[0245] After washing, the mud in the secondary washing kettle is pumped into the filter press for solid-liquid separation, the second solid phase enters the tertiary washing kettle for further washing, and the second liquid phase is used as the washing liquid for the primary washing kettle.

[0246] The third washing liquid is injected into the tertiary washing kettle, and the liquid level reaches 55% of the internal height of the washing kettle. The third washing liquid of the tertiary washing kettle is clean water.

[0247] The second solid phase of the secondary washing kettle after pressure filtration is placed into the tertiary washing kettle, and the amount of the second solid phase is determined according to a predetermined liquid-solid ratio.

[0248] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 55r / min, and the ultrasonic frequency is 40kHz.

[0249] Calcium hydroxide was added to the wash kettle until the pH reached 8.

[0250] Start washing, the washing time is 22min. Select chloride ion (Cl - ) as the tracer ion, and sampling is performed at 5-minute intervals to test the chloride ion content. When the change in the tracer ion content between two adjacent times is less than 10%, the washing is completed.

[0251] After washing, the mud in the tertiary washing kettle is pumped into the filter press for solid-liquid separation to obtain the third liquid phase and the third solid phase. The third liquid phase is used as the washing liquid for the secondary washing kettle.

[0252] Check the content of heavy metals and impurity ions. If they meet the specified standards, the washing is completed.

[0253] The solid phase (ie, the third solid phase) obtained in this embodiment can be reused as a concrete material.

[0254] Specifically, the moisture content of the third solid phase is 22 wt%. The solid phase with this moisture content is transported to a concrete mixing station. The solid phase is diluted to a moisture content of 50 wt% at the concrete mixing station. 0.003 wt% of cellulose ether is added during the dilution. The diluted slurry is metered into a concrete mixer. The added ratio is 18 wt% (wet basis) of the concrete cementitious material.

[0255] Example 2

[0256] This embodiment provides a comprehensive utilization method of secondary aluminum ash, and the following three parts are respectively given specific implementation methods:

[0257] (I) Hydrolysis reaction and treatment of mixed gas

[0258] 1. Powder selection: The secondary aluminum ash is classified by a powder selection machine. After classification, the 125μm sieve residue of the secondary aluminum ash is 4.2%;

[0259] 2. Deoxidation: Place the secondary aluminum ash in a reactor, introduce nitrogen for replacement, and perform deoxidation treatment;

[0260] 3. Hydrolysis: feed materials according to the solid-liquid ratio of 1:3.8, first add about 1 / 3 of the total water into the reactor, add the secondary aluminum ash after deoxidation treatment, then add the remaining water, and then add calcium hydroxide until the pH of the reaction solution is 12.3, and at the same time add 5wt% of the weight of the secondary aluminum ash catalyst to start the reaction. The catalyst formula is: 12 parts of sodium carbonate, 18 parts of sodium hydroxide, 14 parts of calcium carbide slag, and 0.04 parts of sodium stannate.

[0261] The initial reaction temperature is 24°C and the pressure is normal pressure. When the temperature in the reactor reaches 88°C, cooling water is introduced into the inner coil of the reactor, and the flow rate of the cooling water is controlled to control the rising rate of the temperature inside the reactor at 0.5°C / min. When the heating rate of the reactor begins to decrease, the cooling water flow rate is gradually reduced until it is completely closed. After closing, the temperature inside the reactor is about 93°C. When the temperature inside the reactor begins to drop, hot water is introduced into the jacket. The hot water comes from a regenerative thermal incinerator. The temperature of the hot water is 95°C. The flow rate of the hot water entering the jacket is adjusted to keep the temperature inside the reactor at around 92°C.

[0262] 4. Gas collection and purification: The hydrolysis reaction time is 27 hours. During the hydrolysis process, the gas discharged from the reactor is collected, and a multi-stage absorption tower is used to absorb, separate and dry the mixed gas with NH3 as the main component. The gas absorbed by the multi-stage absorption tower is mainly hydrogen. The absorption liquid of the multi-stage absorption tower is clean water. The absorption liquid with ammonia as the main component out of the absorption tower is further utilized.

[0263] The gas separated by the multi-stage absorption tower is mainly hydrogen. The hydrogen is purified by pressure swing adsorption. The purity (mass fraction) of the purified hydrogen is 99.997%. The impurity gas of pressure swing adsorption enters the regenerative thermal incinerator (RTO) for incineration. The heat energy is used to heat the cooling water (inner coil) from the reactor. The heated hot water is used to keep the reactor warm. The water temperature after heating is 97℃.

[0264] 5. Collection and separation of liquid phase and solid phase: The slurry obtained after the hydrolysis reaction is subjected to solid-liquid separation to obtain hydrolyzed mud solid phase and high-salinity alkali ammonia nitrogen hydrolyzate, wherein the high-salinity alkali ammonia nitrogen hydrolyzate has a hydroxide concentration of 0.55 mol / L, an aluminum ion concentration of 16 g / L, a total salinity of 13%, a chloride ion concentration of 28 g / L, an ammonia nitrogen concentration of 1900 mg / L, and sulfide and thiosulfate concentrations of 1.88 g / L and 12 g / L. The water content of the hydrolyzed mud solid phase is 22 wt%.

[0265] (II) Treatment of high-salinity alkaline ammonia nitrogen hydrolyzate

[0266] 1. Separate the high-salinity alkaline ammonia nitrogen hydrolyzate to obtain gaseous ammonia and the first-level liquid phase, and dissolve the gaseous ammonia in water to obtain ammonia water;

[0267] The high-salinity alkaline ammonia nitrogen hydrolyzate is separated from the ammonia nitrogen in the reactor. The reactor speed is set to 50r / min, and air is introduced for aeration. The air flow rate is 12m 3 / min, reaction time 1.5h.

[0268] 2. Dissolving carbon dioxide in the first liquid phase until a specified pH value is reached to obtain a second liquid phase;

[0269] Among them, carbon dioxide was introduced, the carbon dioxide flow rate was set to 1200mL / min, the rotation speed was set to 30r / min, the reaction was stopped when the reaction pH dropped from 14 to about 7, and the slurry was transferred to a belt filter press for solid-liquid separation to obtain aluminum hydroxide and a second liquid phase.

[0270] 3. Dissolving carbon dioxide in the second-stage liquid phase until a specified pH value is reached to obtain a third-stage liquid phase;

[0271] Among them, the second-stage liquid phase is transferred to the reactor, and carbon dioxide is introduced into the reactor. The carbon dioxide flow rate is set to 1300mL / min, and the rotation speed is set to 55r / min. The reaction is stopped when the reaction pH drops from 7 to about 6. The slurry is transferred to a plate and frame filter press for solid-liquid separation to obtain sodium bicarbonate and the third-stage liquid phase.

[0272] 4. Adding an extraction solvent to the third liquid phase and dissolving carbon dioxide until a specified pH value is reached, and obtaining a fourth liquid phase of an organic phase and a fourth liquid phase of an inorganic phase after extraction and separation;

[0273] Among them, the third liquid phase is transferred to the reactor, carbon dioxide is introduced into the reactor, the rotation speed is set to 50r / min, the flow rate of carbon dioxide is 1450L / min, and the extraction solvent (extractant secondary amine + diluent tributyl phosphate) is added at the same time, and the volume ratio of organic phase: inorganic phase is set to 1:2.2. The reaction temperature of the reactor is 21°C, the reaction pressure is 1.8Mpa, and the solubility of carbon dioxide is 0.065mol / L. The reaction pH is reduced from 5 to about 3 to stop the reaction, and the fourth liquid phase of the organic phase and the fourth liquid phase of the inorganic phase are obtained after extraction and separation.

[0274] 5. Evaporating the water in the fourth liquid phase of the inorganic phase;

[0275] Among them, the solution is discharged from the bottom of the reactor, heated to 100°C, and then pumped into the MVR crystallization evaporator, the compressor is started, and sodium sulfate and mother liquor are produced when the sodium sulfate concentration of the mother liquor is reduced to 5%, the temperature is reduced to 50°C, the mother liquor is transported to the MVR evaporator, the compressor is turned on, and sodium chloride is obtained after supersaturation concentration;

[0276] 6. Perform back extraction separation on the fourth-stage liquid phase of the organic phase to obtain an inorganic liquid phase and an organic liquid phase, evaporate the water in the inorganic liquid phase, and return the organic liquid phase to the treatment of the third-stage liquid phase.

[0277] Wherein, after the inorganic phase is separated in step 4, part of the ammonia water in step 1 is added to the fourth-level liquid phase of the organic phase, the volume ratio of the organic phase: the inorganic phase is set to about 1:0.45, the rotation speed is set to 35r / min, and the back extraction separation is performed to obtain the fourth-level liquid phase of the organic phase and reuse it in step 4, and the fourth-level liquid phase of the inorganic phase is concentrated and evaporated to obtain ammonium chloride.

[0278] After the high-salinity alkaline ammonia nitrogen hydrolyzate was treated in this embodiment, the yields of the obtained products were as follows:

[0279]

[0280] (III) Treatment of solid phase of hydrolyzed mud

[0281] The secondary aluminum ash is subjected to a hydrolysis reaction and then filtered to obtain a hydrolysis slurry solid phase, the solid phase after filtration contains 22% water. The solid phase after filtration is sent to a washing kettle for water washing.

[0282] The solid-liquid ratio (mass ratio) in each washing tank is set to 1:4.2, and the first washing liquid is injected into the first washing tank, and the liquid level reaches 60% of the internal height of the washing tank. The first washing liquid comes from the second liquid phase after the mud is pressed at the outlet of the second washing tank.

[0283] The hydrolyzed sludge solid phase after filter pressing is put into the first-stage washing kettle, and the amount of the solid phase is determined according to the amount of washing liquid and the predetermined liquid-solid ratio.

[0284] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 60r / min, and the ultrasonic frequency is 60kHz.

[0285] Introduce CO2 into the primary washing kettle until the pH of the washing liquid reaches 6.8.

[0286] Nitric acid was introduced into the primary washing kettle until the pH of the washing liquid reached 3.5.

[0287] Start washing, the washing time is 25min. Select C l - As a tracer ion, samples were taken at 5-min intervals to test the tracer ion content. - When the content changes by less than 10%, the washing is finished.

[0288] After washing, the mud in the first-stage washing kettle is pumped into the filter press for solid-liquid separation. The first solid phase enters the second-stage washing kettle for further washing, and the first liquid phase is used for secondary aluminum ash hydrolysis.

[0289] The second washing liquid is injected into the secondary washing kettle, and the liquid level reaches 60% of the internal height of the washing kettle. The washing liquid of the secondary washing kettle comes from the third liquid phase after the mud is filtered out of the tertiary washing kettle outlet.

[0290] The first solid phase after filter pressing is placed into the secondary washing kettle, and the amount of the first solid phase is determined according to a predetermined liquid-solid ratio.

[0291] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 60r / min, and the ultrasonic frequency is 60kHz.

[0292] Nitric acid was introduced into the washing kettle until the pH of the washing liquid reached 2.5.

[0293] Start washing, the washing time is 28min. Select C l - As a tracer ion, samples were taken at 5-min intervals to test the Cl - When the tracer ion content changes less than 10% between two times, washing is finished.

[0294] After washing, the mud in the secondary washing kettle is pumped into the filter press for solid-liquid separation, the second solid phase enters the tertiary washing kettle for further washing, and the second liquid phase is used as the washing liquid for the primary washing kettle.

[0295] The third washing liquid is injected into the three-stage washing kettle, and the liquid level reaches 60% of the internal height of the washing kettle. The third washing liquid of the three-stage washing kettle is clean water.

[0296] The second solid phase of the secondary washing kettle after pressure filtration is placed into the tertiary washing kettle, and the amount of the second solid phase is determined according to a predetermined liquid-solid ratio.

[0297] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 55r / min, and the ultrasonic frequency is 40kHz.

[0298] Calcium hydroxide was added to the wash kettle until the pH was 9.

[0299] Start washing, the washing time is 25min. Select C l - As a tracer ion, samples were taken at 5-min intervals to test the Cl - When the tracer ion content changes less than 10% between two washings, washing is finished.

[0300] After washing, the mud in the tertiary washing kettle is pumped into the filter press for solid-liquid separation to obtain the third liquid phase and the third solid phase. The third liquid phase is used as the washing liquid for the secondary washing kettle.

[0301] The content of heavy metals and impurity ions in the third solid phase is tested. If the content meets the specified standards, the washing is completed.

[0302] The solid phase (ie, the third solid phase) obtained in this embodiment can be reused as a concrete material.

[0303] Specifically, the moisture content of the third solid phase is 24 wt%. The solid phase with this moisture content is transported to a concrete mixing station. The solid phase is diluted to a moisture content of 50 wt% at the concrete mixing station. 0.0025 wt% of cellulose ether is added during the dilution. The diluted slurry is metered into a concrete mixer. The added ratio is 22 wt% (wet basis) of the concrete cementitious material.

[0304] Example 3

[0305] This embodiment provides a comprehensive utilization method of secondary aluminum ash, and the following three parts are respectively given specific implementation methods:

[0306] (I) Hydrolysis reaction and treatment of mixed gas

[0307] 1. Powder selection: The secondary aluminum ash is classified by a powder selection machine. After classification, the 125μm sieve residue of the secondary aluminum ash is 5.7%;

[0308] 2. Deoxidation: Place the secondary aluminum ash in a reactor, introduce nitrogen for replacement, and perform deoxidation treatment;

[0309] 3. Hydrolysis: feed materials according to the solid-liquid ratio of 1:4.2, first add about 1 / 3 of the total water into the reactor, add the secondary aluminum ash after deoxidation treatment, then add the remaining water, and then add calcium hydroxide until the pH of the reaction solution is 12.6, and at the same time add 5wt% of the weight of the secondary aluminum ash. Catalyst starts the reaction. The catalyst formula is: 8 parts of sodium carbonate, 24 parts of sodium hydroxide, 12 parts of calcium carbide slag, and 0.04 parts of sodium stannate.

[0310] The initial reaction temperature is 21°C and the pressure is normal pressure. When the temperature in the reactor reaches 92°C, cooling water is introduced into the inner coil of the reactor, and the flow rate of the cooling water is controlled to control the rising rate of the temperature inside the reactor at 0.9°C / min. When the heating rate of the reactor begins to decrease, the cooling water flow rate is gradually reduced until it is completely closed. After closing, the temperature inside the reactor is about 91°C. When the temperature inside the reactor begins to drop, hot water is introduced into the jacket. The hot water comes from a regenerative thermal incinerator. The temperature of the hot water is 95°C. The flow rate of the hot water entering the jacket is adjusted to keep the temperature inside the reactor at around 91°C.

[0311] 4. Gas collection and purification: The hydrolysis reaction time is 33 hours. During the hydrolysis process, the gas discharged from the reactor is collected, and a multi-stage absorption tower is used to absorb, separate and dry the mixed gas with NH3 as the main component. The gas absorbed by the multi-stage absorption tower is mainly hydrogen. The absorption liquid of the multi-stage absorption tower is clean water. The absorption liquid with ammonia as the main component out of the absorption tower is further utilized.

[0312] The gas separated by the multi-stage absorption tower is mainly hydrogen. The hydrogen is purified by pressure swing adsorption. The purity (mass fraction) of the purified hydrogen is 99.995%. The impurity gas of pressure swing adsorption enters the regenerative thermal incinerator (RTO) for incineration. The heat energy is used to heat the cooling water (inner coil) from the reactor. The heated hot water is used to keep the reactor warm. The water temperature after heating is 97℃.

[0313] 5. Collection and separation of liquid and solid phases: The slurry obtained after the hydrolysis reaction is subjected to solid-liquid separation to obtain hydrolyzed mud solid phase and high-salinity alkali ammonia nitrogen hydrolyzate, wherein the high-salinity alkali ammonia nitrogen hydrolyzate has a hydroxide concentration of 0.57 mol / L, an aluminum ion concentration of 13 g / L, a total salinity of 16%, a chloride ion concentration of 25 g / L, an ammonia nitrogen concentration of 1888 mg / L, and sulfide and thiosulfate concentrations of 1.7 g / L and 11 g / L. The water content of the hydrolyzed mud solid phase is 22 wt%.

[0314] (II) Treatment of high-salinity alkaline ammonia nitrogen hydrolyzate

[0315] 1. Separate the high-salinity alkaline ammonia nitrogen hydrolyzate to obtain gaseous ammonia and the first-level liquid phase, and dissolve the gaseous ammonia in water to obtain ammonia water;

[0316] The high-salinity alkaline ammonia nitrogen hydrolyzate is separated from the ammonia nitrogen in the reactor. The reactor speed is set to 46r / min, and air is introduced for aeration. The air flow rate is 13m 3 / min, reaction time 1.3h.

[0317] 2. Dissolving carbon dioxide in the first liquid phase until a specified pH value is reached to obtain a second liquid phase;

[0318] Among them, carbon dioxide was introduced, the carbon dioxide flow rate was set to 1314 mL / min, the rotation speed was set to 38 r / min, the reaction pH was stopped when it dropped from 14 to about 7, and the slurry was transferred to a belt filter press for solid-liquid separation to obtain aluminum hydroxide and a second liquid phase.

[0319] 3. Dissolving carbon dioxide in the second-stage liquid phase until a specified pH value is reached to obtain a third-stage liquid phase;

[0320] Among them, the second-stage liquid phase is transferred to the reactor, and carbon dioxide is introduced into the reactor. The carbon dioxide flow rate is set to 1500mL / min, and the rotation speed is set to 45r / min. The reaction is stopped when the reaction pH drops from 7 to about 6. The slurry is transferred to a plate and frame filter press for solid-liquid separation to obtain sodium bicarbonate and the third-stage liquid phase.

[0321] 4. Adding an extraction solvent to the third liquid phase and dissolving carbon dioxide until a specified pH value is reached, and obtaining a fourth liquid phase of an organic phase and a fourth liquid phase of an inorganic phase after extraction and separation;

[0322] Among them, the third liquid phase is transferred to the reactor, carbon dioxide is introduced into the reactor, the rotation speed is set to 54r / min, the flow rate of carbon dioxide is 1520mL / min, and the extraction solvent (extractant trioctyl tertiary amine + diluent n-pentanol) is added at the same time, and the volume ratio of organic phase: inorganic phase is set to 1:2.3. The reaction temperature of the reactor is 23°C, the reaction pressure is 1.77Mpa, and the solubility of carbon dioxide is 0.06mol / L. The reaction pH is reduced from 6 to about 3 to stop the reaction, and the fourth liquid phase of the organic phase and the fourth liquid phase of the inorganic phase are obtained after extraction and separation.

[0323] 5. Evaporating the water in the fourth liquid phase of the inorganic phase;

[0324] Among them, the solution is discharged from the bottom of the reactor, heated to 100°C, and then pumped into the MVR crystallization evaporator, the compressor is started, and sodium sulfate and mother liquor are produced when the sodium sulfate concentration of the mother liquor is reduced to 5%, the temperature is reduced to 50°C, the mother liquor is transported to the MVR evaporator, the compressor is turned on, and sodium chloride is obtained after supersaturation concentration;

[0325] 6. Perform back extraction separation on the fourth-stage liquid phase of the organic phase to obtain an inorganic liquid phase and an organic liquid phase, evaporate the water in the inorganic liquid phase, and return the organic liquid phase to the treatment of the third-stage liquid phase.

[0326] Wherein, after the inorganic phase is separated in step 4, part of the ammonia water in step 1 is added to the fourth-level liquid phase of the organic phase, the volume ratio of the organic phase: the inorganic phase is set to about 1:0.43, the rotation speed is set to 48r / min, and the back extraction separation is performed to obtain the fourth-level liquid phase of the organic phase and reuse it in step 4, and the fourth-level liquid phase of the inorganic phase is concentrated and evaporated to obtain ammonium chloride.

[0327] After the high-salinity alkaline ammonia nitrogen hydrolyzate was treated in this embodiment, the yields of the obtained products were as follows:

[0328]

[0329] (II) Treatment of hydrolysis mud solid phase

[0330] The solid-liquid ratio (mass ratio) in each washing tank is set to 1:4.2, and the first washing liquid is injected into the first washing tank, and the liquid level reaches 65% of the internal height of the washing tank. The first washing liquid comes from the second liquid phase after the mud is filtered out of the outlet of the second washing tank.

[0331] The hydrolyzed sludge solid phase after filter pressing is put into the first-stage washing kettle, and the amount of the solid phase is determined according to the amount of washing liquid and the predetermined liquid-solid ratio.

[0332] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 60r / min, and the ultrasonic frequency is 35kHz.

[0333] Introduce CO2 into the primary washing kettle until the pH of the washing liquid reaches 6.2.

[0334] Nitric acid was introduced into the primary washing kettle until the pH of the washing liquid reached 3.8.

[0335] Start washing, the washing time is 32min. Select chloride ion (Cl - ) as the tracer ion, sampling was performed at 8-min intervals to test the tracer ion content. When the change in chloride ion content between two times was less than 10%, the washing was completed.

[0336] After washing, the mud in the first-stage washing kettle is pumped into the filter press for solid-liquid separation. The first solid phase enters the second-stage washing kettle for further washing, and the first liquid phase is used for secondary aluminum ash hydrolysis.

[0337] The second washing liquid is injected into the secondary washing kettle, and the liquid level reaches 65% of the internal height of the washing kettle. The washing liquid of the secondary washing kettle comes from the third liquid phase after the mud is pressed and filtered at the outlet of the tertiary washing kettle.

[0338] The first solid phase after filter pressing is placed into the secondary washing kettle, and the amount of the first solid phase is determined according to a predetermined liquid-solid ratio.

[0339] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 60r / min, and the ultrasonic frequency is 35kHz.

[0340] Nitric acid was introduced into the washing kettle until the pH of the washing liquid reached 3.2.

[0341] Start washing, the washing time is 28min. Select chloride ion (Cl - ) as the tracer ion, sampling was performed at 8-min intervals to test the tracer ion content. When the change in chloride ion content between two washings was less than 10%, the washing was completed.

[0342] After washing, the mud in the secondary washing kettle is pumped into the filter press for solid-liquid separation, the second solid phase enters the tertiary washing kettle for further washing, and the second liquid phase is used as the washing liquid for the primary washing kettle.

[0343] The third washing liquid is injected into the three-stage washing kettle, and the liquid level reaches 65% of the internal height of the washing kettle. The third washing liquid of the three-stage washing kettle is clean water.

[0344] The second solid phase of the secondary washing kettle after pressure filtration is placed into the tertiary washing kettle, and the amount of the second solid phase is determined according to a predetermined liquid-solid ratio.

[0345] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 55r / min, and the ultrasonic frequency is 35kHz.

[0346] Add carbide slag to the washing kettle until the pH reaches 10.

[0347] Start washing, the washing time is 28min. Select chloride ion (Cl - ) as the tracer ion, sampling was performed at 8-min intervals to test the tracer ion content. When the change in chloride ion content between two times was less than 10%, the washing was completed.

[0348] After washing, the mud in the tertiary washing kettle is pumped into the filter press for solid-liquid separation to obtain the third liquid phase and the third solid phase. The third liquid phase is used as the washing liquid for the secondary washing kettle.

[0349] The content of heavy metals and impurity ions in the third solid phase is tested. If the content meets the specified standards, the washing is completed.

[0350] The solid phase (ie, the third solid phase) obtained in this embodiment can be reused as a concrete material.

[0351] Specifically, the moisture content of the third solid phase is 18 wt%. The solid phase with this moisture content is transported to a concrete mixing station. The solid phase is diluted to a moisture content of 50 wt% at the concrete mixing station. 0.003 wt% of cellulose ether is added during the dilution. The diluted slurry is metered into a concrete mixer. The added ratio is 21 wt% (wet basis) of the concrete cementitious material.

[0352] Example 4

[0353] This embodiment provides a comprehensive utilization method of secondary aluminum ash, and the following three parts are respectively given specific implementation methods:

[0354] (I) Hydrolysis reaction and treatment of mixed gas

[0355] 1. Powder selection: The secondary aluminum ash is classified by a powder selection machine. After classification, the 125μm sieve residue of the secondary aluminum ash is 2.6;

[0356] 2. Deoxidation: Place the secondary aluminum ash in a reactor, introduce nitrogen for replacement, and perform deoxidation treatment;

[0357] 3. Hydrolysis: feed materials according to the solid-liquid ratio of 1:3.8, first add about 1 / 3 of the total water into the reactor, add the secondary aluminum ash after deoxidation treatment, then add the remaining water, and then add calcium hydroxide until the pH of the reaction solution is 12.8, and at the same time add 4wt% of the weight of the secondary aluminum ash catalyst to start the reaction. The catalyst formula is: 5 parts of sodium carbonate, 16 parts of sodium hydroxide, 14 parts of calcium carbide slag, and 0.01 parts of sodium stannate.

[0358] The initial reaction temperature is 18°C ​​and the pressure is normal pressure. When the temperature in the reactor reaches 82°C, cooling water is introduced into the inner coil of the reactor, and the flow rate of the cooling water is controlled to control the temperature rise rate inside the reactor at 1.1°C / min. When the temperature rise rate of the reactor begins to decrease, the cooling water flow rate is gradually reduced until it is completely closed. After closing, the temperature inside the reactor is about 84°C. When the temperature inside the reactor begins to drop, hot water is introduced into the jacket. The hot water comes from a regenerative thermal incinerator. The temperature of the hot water is 87°C. The flow rate of the hot water entering the jacket is adjusted to keep the temperature inside the reactor at around 85°C.

[0359] 4. Gas collection and purification: The hydrolysis reaction time is 16 hours. During the hydrolysis process, the gas discharged from the reactor is collected, and a multi-stage absorption tower is used to absorb, separate and dry the mixed gas with NH3 as the main component. The gas absorbed by the multi-stage absorption tower is mainly hydrogen. The absorption liquid of the multi-stage absorption tower is clean water. The absorption liquid with ammonia as the main component out of the absorption tower is further utilized.

[0360] The gas separated by the multi-stage absorption tower is mainly hydrogen. The hydrogen is purified by pressure swing adsorption. The purity (mass fraction) of the purified hydrogen is 99.995%. The impurity gas of pressure swing adsorption enters the regenerative thermal incinerator (RTO) for incineration. The heat energy is used to heat the cooling water (inner coil) from the reactor. The heated hot water is used to keep the reactor warm. The water temperature after heating is 91℃.

[0361] 5. Collection and separation of liquid and solid phases: The slurry obtained after the hydrolysis reaction is subjected to solid-liquid separation to obtain hydrolyzed mud solid phase and high-salinity alkali ammonia nitrogen hydrolyzate, wherein the high-salinity alkali ammonia nitrogen hydrolyzate has a hydroxide concentration of 0.59 mol / L, an aluminum ion concentration of 15 g / L, a total salinity of 18%, a chloride ion concentration of 29 g / L, an ammonia nitrogen concentration of 1650 mg / L, and sulfide and thiosulfate concentrations of 1.5 g / L and 16 g / L. The water content of the hydrolyzed mud solid phase is 22 wt%.

[0362] (II) Treatment of high-salinity alkaline ammonia nitrogen hydrolyzate

[0363] 1. Separate the high-salinity alkaline ammonia nitrogen hydrolyzate to obtain gaseous ammonia and the first-level liquid phase, and dissolve the gaseous ammonia in water to obtain ammonia water;

[0364] The high-salinity alkaline ammonia nitrogen hydrolyzate is separated from the ammonia nitrogen in the reactor. The reactor speed is set to 48r / min, and air is introduced for aeration. The air flow rate is 15m 3 / min, reaction time 1.5h.

[0365] 2. Dissolving carbon dioxide in the first liquid phase until a specified pH value is reached to obtain a second liquid phase;

[0366] Among them, carbon dioxide was introduced, the carbon dioxide flow rate was set to 1517mL / min, the rotation speed was set to 44r / min, the reaction pH was stopped when it dropped from 14 to about 7, and the slurry was transferred to a belt filter press for solid-liquid separation to obtain aluminum hydroxide and a second liquid phase.

[0367] 3. Dissolving carbon dioxide in the second-stage liquid phase until a specified pH value is reached to obtain a third-stage liquid phase;

[0368] Among them, the second-stage liquid phase is transferred to the reactor, and carbon dioxide is introduced into the reactor. The carbon dioxide flow rate is set to 1750mL / min, and the rotation speed is set to 56r / min. The reaction is stopped when the reaction pH drops from 7 to about 6. The slurry is transferred to a plate and frame filter press for solid-liquid separation to obtain sodium bicarbonate and the third-stage liquid phase.

[0369] 4. Adding an extraction solvent to the third liquid phase and dissolving carbon dioxide until a specified pH value is reached, and obtaining a fourth liquid phase of an organic phase and a fourth liquid phase of an inorganic phase after extraction and separation;

[0370] Among them, the third liquid phase is transferred to the reactor, carbon dioxide is introduced into the reactor, the rotation speed is set to 60r / min, the flow rate of carbon dioxide is 1780mL / min, and the extraction solvent (extractant trioctylmethyl quaternary ammonium salt + n-hexanol) is added at the same time, and the volume ratio of organic phase: inorganic phase is set to 1:2.11. The reaction temperature of the reactor is 25°C, the reaction pressure is 1.8Mpa, and the solubility of carbon dioxide is 0.07mol / L. The reaction pH is reduced from 5 to about 3 to stop the reaction, and the fourth liquid phase of the organic phase and the fourth liquid phase of the inorganic phase are obtained after extraction and separation.

[0371] 5. Evaporating the water in the fourth liquid phase of the inorganic phase;

[0372] Among them, the solution is discharged from the bottom of the reactor, heated to 100°C, and then pumped into the MVR crystallization evaporator, the compressor is started, and sodium sulfate and mother liquor are produced when the sodium sulfate concentration of the mother liquor is reduced to 5%, the temperature is reduced to 50°C, the mother liquor is transported to the MVR evaporator, the compressor is turned on, and sodium chloride is obtained after supersaturation concentration;

[0373] 6. Perform back extraction separation on the fourth-stage liquid phase of the organic phase to obtain an inorganic liquid phase and an organic liquid phase, evaporate the water in the inorganic liquid phase, and return the organic liquid phase to the treatment of the third-stage liquid phase.

[0374] Among them, after the inorganic is separated in step S105, part of the ammonia water in step S102 is added to the fourth liquid phase of the organic phase, the volume ratio of the organic phase: the inorganic phase is set to about 1:0.49, the rotation speed is set to 50r / min, and the back extraction separation is performed to obtain the fourth liquid phase of the organic phase and reuse it in step S105, and the fourth liquid phase of the inorganic phase is concentrated and evaporated to obtain ammonium chloride.

[0375] After the high-salinity alkaline ammonia nitrogen hydrolyzate was treated in this embodiment, the yields of the obtained products were as follows:

[0376]

[0377] (II) Treatment of hydrolysis mud solid phase

[0378] The solid-liquid ratio (mass ratio) in the first-stage washing kettle is set to 1:6, and the first washing liquid is injected into the first-stage washing kettle, and the liquid level reaches 70% of the internal height of the washing kettle. The first washing liquid comes from the second liquid phase after the mud is pressed at the outlet of the second-stage washing kettle.

[0379] The hydrolyzed sludge solid phase after filter pressing is put into the first-stage washing kettle, and the amount of the solid phase is determined according to the amount of washing liquid and the predetermined liquid-solid ratio.

[0380] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 65r / min, and the ultrasonic frequency is 40kHz.

[0381] Introduce CO2 into the primary washing kettle until the pH of the washing liquid reaches 6.2.

[0382] A mixture of acetic acid and oxalic acid is introduced into the primary washing kettle until the pH of the washing liquid reaches 4.2.

[0383] Start washing, the washing time is 20min. Select C l - As a tracer ion, samples were taken at 6-min intervals to test the tracer ion content. - When the content changes by less than 10%, the washing is finished.

[0384] After washing, the mud in the first-stage washing kettle is pumped into the filter press for solid-liquid separation. The first solid phase enters the second-stage washing kettle for further washing, and the first liquid phase is used for secondary aluminum ash hydrolysis.

[0385] The second washing liquid is injected into the secondary washing kettle, and the liquid level reaches 70% of the internal height of the washing kettle. The washing liquid of the secondary washing kettle comes from the third liquid phase after the mud is pressed and filtered at the outlet of the tertiary washing kettle.

[0386] The first solid phase after filter pressing is placed into the secondary washing kettle, and the amount of the first solid phase is determined according to a predetermined liquid-solid ratio.

[0387] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 65r / min, and the ultrasonic frequency is 40kHz.

[0388] A mixture of acetic acid and oxalic acid was introduced into the washing kettle until the pH of the washing liquid reached 3.2.

[0389] Start washing, the washing time is 28min. Select C l - As a tracer ion, samples were taken at 6-min intervals to test the tracer ion content. - When the content changes by less than 10%, the washing is finished.

[0390] After washing, the mud in the secondary washing kettle is pumped into the filter press for solid-liquid separation, the second solid phase enters the tertiary washing kettle for further washing, and the second liquid phase is used as the washing liquid for the primary washing kettle.

[0391] The third washing liquid is injected into the three-stage washing kettle, and the liquid level reaches 70% of the internal height of the washing kettle. The third washing liquid of the three-stage washing kettle is clean water.

[0392] The second solid phase of the secondary washing kettle after pressure filtration is placed into the tertiary washing kettle, and the amount of the second solid phase is determined according to a predetermined liquid-solid ratio.

[0393] Turn on the agitator and the ultrasonic generator for washing, the agitator speed is 55r / min, and the ultrasonic frequency is 40kHz.

[0394] Add carbide slag to the washing kettle until the pH reaches 10.

[0395] Start washing, the washing time is 25min. Select C l - As a tracer ion, samples were taken at 6-min intervals to test the tracer ion content. - When the content changes by less than 10%, the washing is finished.

[0396] After washing, the mud in the tertiary washing kettle is pumped into the filter press for solid-liquid separation to obtain the third liquid phase and the third solid phase. The third liquid phase is used as the washing liquid for the secondary washing kettle.

[0397] The content of heavy metals and impurity ions in the third solid phase is tested. If the content meets the specified standards, the washing is completed.

[0398] Specifically, the moisture content of the third solid phase is 24wt%. The solid phase with this moisture content is transported to a concrete mixing station. The solid phase is diluted to a moisture content of 50wt% at the concrete mixing station. 0.002wt% of cellulose ether is added during the dilution. The diluted slurry is metered into a concrete mixer. The added ratio is 22wt% (wet basis) of the concrete cementitious material.

[0399] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for comprehensive utilization of secondary aluminum ash, characterized in that: include: Deoxidize the secondary aluminum ash; The deoxidized secondary aluminum ash is subjected to hydrolysis treatment and solid-liquid separation to obtain mixed gas, hydrolysis slurry solid phase and high-salinity alkali ammonia nitrogen hydrolyzate; Separating and purifying the mixed gas to obtain hydrogen; The hydrolyzed slurry solid phase is subjected to at least two acid washing treatments and at least one alkali washing treatment to obtain a solid phase product for concrete admixture; The high-salinity alkaline ammonia nitrogen hydrolyzate is subjected to ammonia nitrogen separation and stepwise acidification treatment to obtain aluminum hydroxide and inorganic salt crystals.

2. The comprehensive utilization method of secondary aluminum ash according to claim 1, characterized in that: In the step of hydrolyzing the deoxidized secondary aluminum ash to obtain a mixed gas, a hydrolysis slurry solid phase and a high-salinity alkali ammonia nitrogen hydrolyzate: The secondary aluminum ash is mixed with water at a solid-liquid ratio of 1:(2-10), and calcium hydroxide and a catalyst are added, and hydrolyzed at 5-99°C for 5-48h; the gas collected during the hydrolysis process is the mixed gas, the liquid phase obtained by solid-liquid separation of the hydrolysis product is a high-salinity alkaline ammonia nitrogen hydrolyzate, and the solid phase obtained is a hydrolysis slurry solid phase; Wherein, the weight ratio of the calcium hydroxide to the deoxidized secondary aluminum ash is (1-10):100, and the weight ratio of the catalyst to the deoxidized secondary aluminum ash is (1-10):100; The catalyst comprises, by weight: 0-10 parts of sodium carbonate, 0-10 parts of potassium carbonate, 10-80 parts of sodium hydroxide, 0-50 parts of potassium hydroxide, 5-30 parts of carbide slag, and 0.01-5 parts of sodium stannate.

3. The comprehensive utilization method of secondary aluminum ash according to claim 1 or 2, characterized in that: The temperature during the hydrolysis treatment is carried out according to the following procedure: Add secondary aluminum ash, water, catalyst and calcium hydroxide into the reactor. When the temperature in the reactor rises to 70-90°C, cool it with a cooling medium so that the temperature rise rate in the reactor is controlled to be 0.1-3°C / min. When the temperature rise rate in the reactor decreases, gradually reduce the amount of cooling medium to maintain the temperature in the reactor at 80-90°C; When the temperature in the reactor begins to drop, heating medium is used for heating, and the amount of heating medium is adjusted to maintain the temperature in the reactor at 80-90°C; wherein the difference between the temperature of the heating medium and the temperature in the reactor is 1-10°C.

4. The comprehensive utilization method of secondary aluminum ash according to claim 1, characterized in that: The step of deoxidizing the secondary aluminum ash comprises: The secondary aluminum ash is graded so that the residue on a 125 μm sieve is 1-10%; The secondary aluminum ash is deoxidized by nitrogen replacement.

5. The comprehensive utilization method of secondary aluminum ash according to claim 1, characterized in that: The steps of subjecting the hydrolyzed slurry solid phase to at least two acid washing treatments and at least one alkali washing treatment to obtain a solid phase product for concrete admixture include: Injecting a first washing liquid into the first washing kettle and sending the hydrolyzed slurry solid phase into the washing kettle, wherein the first washing liquid comes from the second liquid phase after the slurry is filtered out at the outlet of the second washing kettle; Passing a first gas into the primary washing kettle until the pH value of the washing liquid reaches a first preset value; Passing an acidic solution into the primary washing kettle until the pH of the washing solution reaches a second preset value; After the washing in the first washing kettle is completed, the slurry is subjected to solid-liquid separation to obtain a first liquid phase and a first solid phase, wherein the first liquid phase can be used for secondary aluminum ash hydrolysis treatment; Injecting a second washing liquid into the secondary washing kettle and sending the first solid phase into the washing kettle for further washing, wherein the second washing liquid comes from the third liquid phase after the mud is filtered out at the outlet of the tertiary washing kettle; Passing an acidic solution into the secondary washing kettle until the pH of the washing solution reaches a second preset value; After the washing in the secondary washing kettle is completed, the slurry is subjected to solid-liquid separation to obtain a second liquid phase and a second solid phase; Injecting a third washing liquid into the tertiary washing kettle and feeding the second solid phase into the kettle for washing, wherein the third washing liquid is water; introducing an alkaline substance into the third-stage washing kettle until the pH value of the washing liquid reaches a third preset value; After the washing in the three-stage washing kettle is completed, the slurry is subjected to solid-liquid separation to obtain a third liquid phase and a third solid phase; The content of heavy metals and impurity ions in the third solid phase is detected. If it meets the specified standards, washing is completed and the third solid phase is the solid phase product. If it does not meet the specified standards, the washing of the three-stage washing kettle is repeated.

6. The comprehensive utilization method of secondary aluminum ash according to claim 5, characterized in that: The solid-liquid ratio of the first-stage washing kettle, the second-stage washing kettle and the third-stage washing kettle is 1:(3-10) by mass ratio; The liquid level of the washing liquid in the first-stage washing kettle, the second-stage washing kettle and the third-stage washing kettle is 50-80% of the internal height of the washing kettle; The first gas is CO2, and the first preset value of pH is 6-7; The acidic solution is one or a combination of sulfuric acid, nitric acid, and organic acid, and the second preset pH value is 2-6; The alkaline substance is one or a combination of calcium hydroxide, sodium hydroxide and carbide slag, and the third preset pH value is 7-12; The first-stage washing kettle, the second-stage washing kettle and the third-stage washing kettle are operated with the ultrasonic generator and the agitator turned on for washing, wherein the rotation speed of the agitator is 20-80 r / min, and the ultrasonic frequency of the ultrasonic generator is 20-80 kHz.

7. The comprehensive utilization method of secondary aluminum ash according to claim 1, characterized in that: The steps of separating ammonia nitrogen from the high-salinity alkaline ammonia nitrogen hydrolyzate and performing stepwise acidification treatment to obtain aluminum hydroxide and inorganic salt crystals include: Separating the high-salinity alkaline ammonia nitrogen hydrolyzate to obtain a gas phase and a first-stage liquid phase; dissolving carbon dioxide in the first liquid phase until a specified pH value is reached to obtain a second liquid phase; dissolving carbon dioxide in the second-stage liquid phase until a specified pH value is reached to obtain a third-stage liquid phase; Adding an extraction solvent to the third liquid phase and dissolving carbon dioxide until a specified pH value is reached, and obtaining a fourth liquid phase of an organic phase and a fourth liquid phase of an inorganic phase after extraction and separation; Evaporating the water in the fourth liquid phase of the inorganic phase; The fourth-stage liquid phase of the organic phase is subjected to back extraction separation to obtain an inorganic liquid phase and an organic liquid phase, the water in the inorganic liquid phase is evaporated, and the organic liquid phase is returned to the treatment of the third-stage liquid phase.

8. The comprehensive utilization method of secondary aluminum ash according to claim 7, characterized in that: In the step of separating ammonia nitrogen from the high-salt alkali ammonia nitrogen hydrolyzate to obtain a gas phase and a first-stage liquid phase: The high-salinity alkaline ammonia nitrogen hydrolyzate is introduced into the reactor, the speed of the reactor is set to 40-150r / min, and air is introduced for aeration, with an air flow rate of 10-30m 3 / min, reaction time 0.5-3h, the obtained ammonia gas is passed into an absorption tower to obtain ammonia water; The temperature of the high-salinity alkaline ammonia nitrogen hydrolyzate is 80-95°C, the alkalinity is 0.20-2.0 mol / L, the total salt content is 5-25%, and the ammonia nitrogen concentration is 200-2000 mg / L; The speed of the reactor is set to 40-150r / min, and air is introduced for aeration, with an air flow rate of 10-30m 3 / min, reaction time 0.5-3h, the obtained ammonia gas is passed into an absorption tower to obtain ammonia water; In the step of dissolving carbon dioxide in the first liquid phase until a specified pH value is reached to obtain a second liquid phase: Introduce carbon dioxide into the first-stage liquid phase, set the carbon dioxide flow rate to 1000-3000 mL / min, set the rotation speed to 30-150 r / min, stop the reaction when the reaction pH drops from 12-14 to 7-8, separate the slurry into solid and liquid, and obtain aluminum hydroxide and the second-stage liquid phase; In the step of dissolving carbon dioxide in the second-stage liquid phase until a specified pH value is reached to obtain a third-stage liquid phase: The second-stage liquid phase is transferred to a reactor, and carbon dioxide is introduced into the reactor. The carbon dioxide flow rate is set to 1000-3000 mL / min, and the rotation speed is set to 40-150 r / min. The reaction is stopped when the pH value of the reaction decreases from 7-8 to 5-6, and the slurry is subjected to solid-liquid separation to obtain sodium bicarbonate and the third-stage liquid phase; In the step of adding an extraction solvent to the third liquid phase and dissolving carbon dioxide until a specified pH value is reached, and obtaining a fourth liquid phase of an organic phase and a fourth liquid phase of an inorganic phase after extraction and separation: The third liquid phase is transferred to a reaction kettle, carbon dioxide is introduced into the kettle, and an extraction solvent is added at the same time. The volume ratio of the organic phase: the inorganic phase is set to (1-2): (2-3), and the solubility of carbon dioxide is set to 0.05-0.08 mol / L. The reaction is stopped when the reaction pH drops from 5-6 to 3-4. After extraction and separation, a fourth liquid phase of the organic phase and a fourth liquid phase of the inorganic phase are obtained; the fourth liquid phase of the organic phase contains chlorine.

9. The comprehensive utilization method of secondary aluminum ash according to claim 8, characterized in that: The extraction solvent comprises an extractant and a diluent, wherein the extractant is one or more of alkyl primary amine, secondary amine, trioctyl tertiary amine, trioctyl methyl quaternary ammonium salt; the diluent is one or more of kerosene, tributyl phosphate, n-pentanol, n-hexanol, n-octanol, isooctyl alcohol; The flow rate of the carbon dioxide is 1000-3000mL / min; The rotation speed of the reactor is set to 40-150 r / min, the reaction temperature is 20-25° C., and the reaction pressure is 1-3 Mpa.

10. The comprehensive utilization method of secondary aluminum ash according to claim 7, characterized in that: In the step of evaporating the water in the fourth liquid phase of the inorganic phase: The fourth-stage liquid phase of the inorganic phase is discharged from the bottom of the reactor and heated to 90-100° C., and then pumped into the MVR evaporator, and the compressor is started to produce sodium sulfate and mother liquor when the sodium sulfate is supersaturated; When the sodium sulfate concentration of the mother liquor is reduced to 3-7% and the temperature is reduced to 45-55°C, the mother liquor is transported to the MVR evaporator, the compressor is turned on, and sodium chloride is obtained after supersaturation concentration.

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