Method and system for treating heavy metals and foreign ions in secondary aluminum ash

Abstract

The invention relates to the technical field of industrial solid waste comprehensive treatment, and discloses a treatment method and system for heavy metal and impurity ions in secondary aluminum ash, and the method comprises the following steps: carrying out hydrolysis reaction on the secondary aluminum ash, and carrying out filter pressing to obtain a hydrolysis slurry solid phase; washing the hydrolyzed slurry solid phase for multiple times, and performing solid-liquid separation on the slurry of the previous washing in each washing to obtain a solid phase and a liquid phase; wherein the treatment of the solid phase comprises the following steps: mixing a washing solution in the solid phase, adjusting the pH value, washing, and measuring the contents of heavy metals and impurity ions after washing; the liquid phase treatment comprises the following steps: collecting the liquid phase after each time of solid-liquid separation, dissolving carbon dioxide in the liquid phase and / or introducing an acid solution to serve as a washing solution for the previous time of solid-phase treatment. By adopting the method, heavy metals and impurity ions in the treated secondary aluminum ash can meet specified standards, and reutilization of resources is realized.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive disposal of industrial solid waste, and in particular to a method and system for treating heavy metals and impurity ions in secondary aluminum ash. Background Art

[0002] Secondary aluminum ash is aluminum-containing solid waste after most of the metallic aluminum is recovered from primary aluminum ash. Secondary aluminum ash contains a variety of heavy metals, some of which have a high content. It also contains a large amount of chlorides, fluorides and alkali metal salts. － 、F － , K + 、Na + Called impurity ions, secondary aluminum ash has a complex composition and is difficult to handle.

[0003] The disposal methods of secondary aluminum ash are mainly divided into pyrolysis and wet treatment (mainly hydrolysis). Among them, the pyrolysis method mainly involves putting the pretreated aluminum ash into a calcining furnace for high-temperature calcination, usually at a high temperature of more than 1000°C. During the calcination process, the aluminum ash will undergo a series of chemical reactions and physical changes to produce gaseous and liquid products. The calcined aluminum ash is then cooled and separated to separate the gaseous and liquid products, and then treated harmlessly. Although the collected products can be reused after pyrolysis treatment, the pyrolysis process requires high-temperature calcination, high energy consumption, and low efficiency. Moreover, the treatment effect of heavy metals and impurity ions is not ideal, and it is easy to cause secondary pollution.

[0004] The hydrolysis method is to mix the secondary aluminum ash with a liquid medium (water) to react chemically, and aluminum nitride, elemental aluminum and its compounds are hydrolyzed, and the products are mainly metaaluminate and filter residue. The hydrolysis method is one of the common methods for treating secondary aluminum ash. The content of heavy metals and impurity ions contained in the secondary aluminum ash treated by the hydrolysis method is not 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.

[0005] Moreover, during this treatment process, the liquid medium (water) is not treated sufficiently, and the harmlessness of the liquid medium cannot be achieved, which has a negative impact on the environment. In addition, the amount of wastewater will increase when new liquid medium (water) is added for use, and when fresh water is not added, the concentration of heavy metals and impurity ions after cleaning will become higher and higher, and the final wastewater discharge may be more troublesome, accelerate equipment degradation, and may also have undesirable reactions with secondary aluminum ash. Summary of the invention

[0006] The first technical problem to be solved by the present invention is to provide a method and system for wet treatment of secondary aluminum ash to remove heavy metals and impurity ions, so that the heavy metals and impurity ions in the treated secondary aluminum ash meet the specified standards and realize resource recycling.

[0007] In order to achieve the above technical effect, the present invention provides a method for treating heavy metals and impurity ions in secondary aluminum ash, comprising: subjecting the secondary aluminum ash to a hydrolysis reaction, and then filtering to obtain a hydrolysis slurry solid phase;

[0008] The hydrolysis slurry solid phase is washed multiple times, and in each washing, the slurry from the previous washing is subjected to solid-liquid separation to obtain a solid phase and a liquid phase;

[0009] The treatment of the solid phase includes: mixing a washing liquid in the solid phase, adjusting the pH value and washing, and measuring the content of heavy metals and impurity ions after washing;

[0010] The treatment of the liquid phase includes: collecting the liquid phase after each solid-liquid separation, dissolving carbon dioxide in the liquid phase and / or introducing an acidic solution to be used as a washing liquid for the previous solid phase treatment.

[0011] As an improvement of the above scheme, the method for treating heavy metals and impurity ions in secondary aluminum ash includes:

[0012] The secondary aluminum ash is subjected to a hydrolysis reaction and then filtered to obtain a hydrolysis slurry solid phase;

[0013] The hydrolysis slurry solid phase is washed at least three times, and in the first washing, the second washing, and the third washing, the slurry of the previous washing is subjected to solid-liquid separation to obtain a solid phase and a liquid phase;

[0014] The treatment of the solid phase includes: mixing a washing liquid in the solid phase, adjusting the pH value and washing, and measuring the content of heavy metals and impurity ions after washing;

[0015] The treatment of the liquid phase includes: collecting the liquid phase after solid-liquid separation in the first washing, the second washing, and the third washing, dissolving carbon dioxide and / or passing an acidic solution into the liquid phase, and using it as a washing liquid for solid phase treatment in the first washing and the second washing.

[0016] As an improvement of the above scheme, the method for treating heavy metals and impurity ions in secondary aluminum ash includes:

[0017] The secondary aluminum ash is subjected to a hydrolysis reaction and then filtered to obtain a hydrolysis slurry solid phase;

[0018] Injecting a first washing liquid into the first washing kettle and sending the hydrolyzed mud solid phase into the washing kettle, wherein the first washing liquid comes from the second liquid phase after the mud is filtered out at the outlet of the second washing kettle;

[0019] Passing a first gas into the primary washing kettle until the pH value of the washing liquid reaches a first preset value;

[0020] Passing an acidic solution into the primary washing kettle until the pH of the washing solution reaches a second preset value;

[0021] 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;

[0022] 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;

[0023] Passing an acidic solution into the secondary washing kettle until the pH of the washing solution reaches a second preset value;

[0024] 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;

[0025] 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;

[0026] Passing an alkaline solution into the third-stage washing kettle until the pH of the washing solution reaches a third preset value;

[0027] 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;

[0028] The content of heavy metals and impurity ions in the third solid phase is detected. If it meets the specified standard, the washing is completed. If it does not meet the specified standard, the washing of the three-stage washing kettle is repeated.

[0029] As an improvement of the above scheme, 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;

[0030] The liquid level height 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.

[0031] As an improvement of the above solution, the first gas is CO2, and the first preset value of pH is 6-7;

[0032] 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;

[0033] The alkaline solution is one or a combination of calcium hydroxide, sodium hydroxide and carbide slag, and the third preset pH value is 7-12.

[0034] As an improvement of the above scheme, the conditions for determining the end of washing of the first-stage washing kettle, the second-stage washing kettle, and the third-stage washing kettle include:

[0035] One or more heavy metal or impurity ions are selected as tracer ions and sampling is performed at preset intervals;

[0036] 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;

[0037] Wherein, the preset interval time is 5-20 minutes, preferably 5-10 minutes; the preset ion value is 5-10%, preferably 5-8%.

[0038] As an improvement of the above scheme, the heavy metals in the secondary aluminum ash 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 .

[0039] As an improvement of the above scheme, 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.

[0040] As an improvement of the above scheme, the hydrolysis reaction of the secondary aluminum ash and the subsequent pressure filtration to obtain the hydrolysis slurry solid phase comprises:

[0041] The secondary aluminum ash is subjected to a hydrolysis reaction to obtain a slurry;

[0042] The hydrolyzed mud is sent to a filter press for solid-liquid separation, and a hydrolyzed mud solid phase is obtained after filtration. The water content of the hydrolyzed mud solid phase is 15-25%.

[0043] Accordingly, the present invention provides a system using the above-mentioned method for treating heavy metals and impurity ions in secondary aluminum ash, comprising: a hydrolysis reaction unit for hydrolyzing the secondary aluminum ash;

[0044] A primary washing kettle connected to the hydrolysis reaction unit for washing the hydrolysis slurry solid phase obtained after hydrolysis pressure filtration;

[0045] A secondary washing kettle connected to the primary washing kettle for washing the first solid phase obtained after washing in the primary washing kettle;

[0046] a tertiary washing kettle connected to the secondary washing kettle for washing the second solid phase obtained after washing in the secondary washing kettle; and

[0047] A tracer ion detection unit for detecting the content of heavy metals and impurity ions in the first solid phase, the second solid phase and / or the third solid phase.

[0048] As an improvement of the above scheme, the first-stage washing kettle, the second-stage washing kettle and the third-stage washing kettle all include a washing kettle body, the washing kettle body includes a kettle body, a feeding port and a water inlet arranged at the upper part of the kettle body, a discharge valve and a mud pump arranged at the lower part of the kettle body, an ultrasonic and spoiler plate, an agitator and an aeration pipe arranged inside the kettle body, and an electric power unit for controlling the rotation of the agitator;

[0049] The ultrasonic and spoiler plate is arranged on the inner wall of the kettle body;

[0050] The aeration pipe is arranged at the bottom of the kettle body, and comprises an aeration main pipe and an annular aeration pipe. The annular aeration pipe comprises a plurality of annular aeration sub-pipes arranged in concentric circles, and the plurality of annular aeration sub-pipes are connected to the aeration main pipe.

[0051] The implementation of the present invention has the following beneficial effects:

[0052] (1) The secondary aluminum ash of the present invention is sequentially hydrolyzed and washed multiple times. In each washing, the slurry of the previous washing is subjected to solid-liquid separation to obtain a solid phase and a liquid phase. The washing liquid is mixed in the solid phase, the pH value is adjusted and washing is performed, and the content of heavy metals and impurity ions is measured after washing to achieve harmless treatment of the solid phase; as for liquid phase treatment, the liquid phase after each solid-liquid separation is collected, carbon dioxide is dissolved in the liquid phase and / or an acidic solution is introduced, and the washing liquid used for the previous solid phase treatment effectively reduces the water consumption and improves the elution efficiency of heavy metals and impurity ions, and both the solid phase and the liquid phase can achieve harmless treatment.

[0053] (2) 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. In addition, the present invention uses CO2 as a pH regulator, and CO2 is converted into carbonate, realizing a negative carbon process.

[0054] (3) The present invention determines a method for selecting tracer ions and performs full-process dynamic monitoring in the first-stage washing kettle, the second-stage washing kettle, and the third-stage washing kettle, which can quickly determine the washing effect and whether the heavy metal and impurity ions meet the standards after the washing.

[0055] (4) The washing kettle of the present invention is provided with an ultrasonic wave and a spoiler. The ultrasonic wave provides oscillation of the liquid phase, and the spoiler forms a vortex inside the washing kettle. The two together improve the washing efficiency and significantly improve the elution efficiency of heavy metals and impurity ions.

[0056] The heavy metals and impurity ions in the secondary aluminum ash solid phase treated by the present invention meet the requirements and can be reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic diagram of an embodiment of a method for treating heavy metals and impurity ions in secondary aluminum ash of the present invention;

[0058] Figure 2 yes Figure 1 The flowchart of the method for treating heavy metals and impurity ions in secondary aluminum ash is shown;

[0059] Figure 3 It is a schematic diagram of a system for treating heavy metals and impurity ions in secondary aluminum ash of the present invention;

[0060] Figure 4 It is a schematic diagram of the washing kettle body of the present invention;

[0061] Figure 5 Schematic diagram of an aeration tube of the present invention. DETAILED DESCRIPTION

[0062] 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.

[0063] The secondary aluminum ash has complex components and is difficult to process. To this end, the present invention provides a method for treating heavy metals and impurity ions in secondary aluminum ash, which can remove heavy metals and impurity ions from the secondary aluminum ash after hydrolysis. The heavy metals in the secondary aluminum ash include Pb, Cd, Cr, Cu, Ni, Zn, and Mn, and the impurity ions include Cl - 、F - , K + 、Na + .

[0064] The method for treating heavy metals and impurity ions in secondary aluminum ash comprises:

[0065] The secondary aluminum ash is subjected to a hydrolysis reaction and then filtered to obtain a hydrolysis slurry solid phase;

[0066] The hydrolysis slurry solid phase is washed multiple times, and in each washing, the slurry from the previous washing is subjected to solid-liquid separation to obtain a solid phase and a liquid phase;

[0067] The treatment of the solid phase includes: mixing a washing liquid in the solid phase, adjusting the pH value and washing, and measuring the content of heavy metals and impurity ions after washing;

[0068] The treatment of the liquid phase includes: collecting the liquid phase after each solid-liquid separation, dissolving carbon dioxide in the liquid phase and / or introducing an acidic solution to be used as a washing liquid for the previous solid phase treatment.

[0069] The secondary aluminum ash of the present invention is sequentially hydrolyzed and washed multiple times. In each washing, the slurry of the previous washing is subjected to solid-liquid separation to obtain a solid phase and a liquid phase. The washing liquid is mixed in the solid phase, the pH value is adjusted and washing is performed, and the content of heavy metals and impurity ions is measured after washing to achieve harmless treatment of the solid phase; as for liquid phase treatment, the liquid phase after each solid-liquid separation is collected, carbon dioxide is dissolved in the liquid phase and / or an acidic solution is introduced, and the washing liquid used for the previous solid phase treatment effectively reduces the water consumption and improves the elution efficiency of heavy metals and impurity ions, and both the solid phase and the liquid phase can achieve harmless treatment.

[0070] The secondary aluminum ash solid phase treated by the present invention has heavy metals and impurity ions that meet the requirements and can be reused, for example, as concrete material, but not limited to this.

[0071] 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.

[0072] Preferably, the method for treating heavy metals and impurity ions in secondary aluminum ash comprises:

[0073] The secondary aluminum ash is subjected to a hydrolysis reaction and then filtered to obtain a hydrolysis slurry solid phase;

[0074] The hydrolysis slurry solid phase is washed at least three times, and in the first washing, the second washing, and the third washing, the slurry of the previous washing is subjected to solid-liquid separation to obtain a solid phase and a liquid phase;

[0075] The treatment of the solid phase includes: mixing a washing liquid in the solid phase, adjusting the pH value and washing, and measuring the content of heavy metals and impurity ions after washing;

[0076] The treatment of the liquid phase includes: collecting the liquid phase after solid-liquid separation in the first washing, the second washing, and the third washing, dissolving carbon dioxide and / or passing an acidic solution into the liquid phase, and using it as a washing liquid for solid phase treatment in the first washing and the second washing.

[0077] Specifically, Figure 1 As shown, the present invention provides a preferred embodiment of a method for treating heavy metals and impurity ions in secondary aluminum ash, comprising:

[0078] S101, subjecting the secondary aluminum ash to a hydrolysis reaction, and then filtering it to obtain a hydrolysis slurry solid phase;

[0079] Specifically, step S101 includes:

[0080] The secondary aluminum ash is subjected to a hydrolysis reaction to obtain a slurry;

[0081] The hydrolyzed slurry is sent to a filter press for solid-liquid separation, and a solid phase of the hydrolyzed slurry is obtained after filtration, wherein the water content of the solid phase of the hydrolyzed slurry is 15-25%. The solid phase after filtration is sent to a washing kettle for water washing.

[0082] Preferably, the secondary aluminum ash is added to a certain amount of water, the mass ratio of the secondary aluminum ash to water can be (1-2): (1-20), a hydrolysis reaction is carried out to obtain mud, and then a hydrolysis mud solid phase is obtained after filter pressing. Among them, the hydrolysis reaction temperature is preferably 15-40°C, and the hydrolysis time is preferably 5-15h, but not limited thereto. The mud after hydrolysis contains heavy metals such as Pb, Cd, Cr, Cu, Ni, Zn, Mn, and Cl - 、F - , K + 、Na + And other impurity ions.

[0083] S102, 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;

[0084] Preferably, the stirrer and the ultrasonic generator are turned on for washing, wherein the stirrer rotates at 20-80 r / min, preferably 40-60 r / min, and the ultrasonic frequency is 20-80 kHz, preferably 30-50 kHz. More preferably, an ultrasonic and spoiler plate is provided in the washing kettle, the ultrasonic wave provides oscillation of the liquid phase, and the spoiler plate forms a vortex inside the washing kettle, which together improve the washing efficiency and significantly improve the elution efficiency of heavy metals and impurity ions.

[0085] 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.

[0086] 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.

[0087] S103, introducing a first gas into the primary washing kettle until the pH value of the washing liquid reaches a first preset value.

[0088] Preferably, the first gas is CO2, and CO2 is introduced into the primary washing kettle until the pH value of the washing liquid is 6-7.

[0089] 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.

[0090] S104, introducing an acidic solution into the primary washing kettle until the pH of the washing solution reaches a second preset value;

[0091] Preferably, 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, 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.

[0092] 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 minutes, more preferably 5-30 minutes.

[0093] 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.

[0094] S104 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.

[0095] Preferably, the selection conditions of the tracer ions include:

[0096] In the solid phase of the first-stage washing tank, the content of heavy metals and impurity ions is tested and recorded as A1;

[0097] Check the contents of heavy metals and impurity ions in the solid phase of the hydrolyzed mud, denoted as A2;

[0098] Calculate A1 / A2 and select an ion with the maximum value as the tracer ion.

[0099] 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 can be 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%.

[0100] S105, 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;

[0101] Preferably, after washing, the mud in the first washing kettle is pumped into a filter press for solid-liquid separation. The solid phase after filtration 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, which effectively reduces water consumption and improves the elution efficiency of heavy metals and impurity ions.

[0102] S106, 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;

[0103] Preferably, the stirrer and the ultrasonic generator are turned on for washing, wherein the stirrer rotates at 20-80 r / min, preferably 40-60 r / min, and the ultrasonic frequency is 20-80 kHz, preferably 30-50 kHz. More preferably, an ultrasonic and spoiler plate is provided in the washing kettle, the ultrasonic wave provides oscillation of the liquid phase, and the spoiler plate forms a vortex inside the washing kettle, which together improve the washing efficiency and significantly improve the elution efficiency of heavy metals and impurity ions.

[0104] 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 pressed at the outlet of the tertiary washing kettle.

[0105] 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.

[0106] S107, introducing an acidic solution into the secondary washing kettle until the pH of the washing solution reaches a second preset value;

[0107] Preferably, 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, 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.

[0108] The temperature of the secondary washing kettle is preferably controlled at 15-40°C, more preferably 20-35°C.

[0109] After the acid solution is introduced, washing begins, and the washing time is preferably 5-50 minutes, more preferably 5-30 minutes.

[0110] 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.

[0111] S107 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.

[0112] Preferably, the selection conditions of the tracer ions include:

[0113] In the solid phase of the secondary washing tank, the content of heavy metals and impurity ions is tested and recorded as A1;

[0114] Check the contents of heavy metals and impurity ions in the solid phase of the hydrolyzed mud, denoted as A2;

[0115] Calculate A1 / A2 and select an ion with the maximum value as the tracer ion.

[0116] 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 can be 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%.

[0117] S108, 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;

[0118] Preferably, after washing is completed, the mud in the secondary washing kettle is sent to the filter press by a mud pump for solid-liquid separation. The water content of the solid phase after filtration is about 15-25%. The second solid phase enters the tertiary washing kettle for further washing, and 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.

[0119] S109, injecting a third washing liquid into the third-stage washing kettle, and sending the second solid phase into the washing kettle for washing, wherein the third washing liquid is water;

[0120] Preferably, the stirrer and the ultrasonic generator are turned on for washing, wherein the stirrer rotates at 20-80 r / min, preferably 40-60 r / min, and the ultrasonic frequency is 20-80 kHz, preferably 30-50 kHz. More preferably, an ultrasonic and spoiler plate is provided in the washing kettle, the ultrasonic wave provides oscillation of the liquid phase, and the spoiler plate forms a vortex inside the washing kettle, which together improve the washing efficiency and significantly improve the elution efficiency of heavy metals and impurity ions.

[0121] 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.

[0122] The second solid phase is placed into 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.

[0123] S110, introducing an alkaline solution into the third-stage washing kettle until the pH of the washing solution reaches a third preset value;

[0124] Preferably, the alkaline solution 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 solution is introduced into the tertiary washing kettle, which can dissolve heavy metals and impurity ions in the liquid phase to a greater extent. Among them, the temperature of the tertiary washing kettle is preferably controlled at 15-40°C, more preferably 20-35°C.

[0125] After the alkaline solution is introduced, washing begins. The washing time is preferably 5-50 minutes, more preferably 5-30 minutes.

[0126] 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.

[0127] S110 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.

[0128] Preferably, the selection conditions of the tracer ions include:

[0129] In the solid phase of the third-stage washing kettle, the content of heavy metals and impurity ions is tested and recorded as A1;

[0130] Check the contents of heavy metals and impurity ions in the solid phase of the hydrolyzed mud, denoted as A2;

[0131] Calculate A1 / A2 and select an ion with the maximum value as the tracer ion.

[0132] 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 can be 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%.

[0133] S111, 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;

[0134] Preferably, after washing, 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.

[0135] S112, detecting the content of heavy metals and impurity ions in the third solid phase, if it meets the specified standard, washing is completed, if it does not meet the specified standard, repeating the washing of the three-stage washing kettle.

[0136] In this embodiment, (1) the secondary aluminum ash of the present invention is sequentially subjected to hydrolysis, first washing, second washing and third washing, and a distributed washing method is adopted. The first liquid phase obtained after washing is used for secondary aluminum ash hydrolysis, the second liquid phase is used as the first washing liquid, the third liquid phase is used as the second washing liquid, and water is used as the third washing liquid, which effectively reduces the water consumption and improves the elution efficiency of heavy metals and impurity ions, and both the solid phase and the liquid phase can be harmlessly treated.

[0137] (2) In the first-stage washing process, the present invention introduces the first gas CO2 until the pH of the washing liquid reaches the first preset value of 6-7, and then introduces the acidic solution until the pH of the washing liquid reaches the second preset value of 2-6; then introduces the acidic solution during the second-stage washing process until the pH of the washing liquid reaches the second preset value of 2-6; finally, in the third-stage washing process, an alkaline solution is introduced until the pH of the washing liquid reaches the third preset value of 7-12. The present invention introduces different substances at different stages to adjust the pH value of the mud, 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, thereby realizing a negative carbon process.

[0138] (3) The present invention determines a method for selecting tracer ions and performs full-process dynamic monitoring in the first-stage washing kettle, the second-stage washing kettle, and the third-stage washing kettle, which can quickly determine the washing effect and whether the heavy metal and impurity ions meet the standards after the washing.

[0139] (4) The washing kettle of the present invention is provided with an ultrasonic wave and a spoiler. The ultrasonic wave provides oscillation of the liquid phase, and the spoiler forms a vortex inside the washing kettle. The two together improve the washing efficiency and significantly improve the elution efficiency of heavy metals and impurity ions. The heavy metals and impurity ions in the secondary aluminum ash solid phase treated by the present invention meet the requirements and can be reused.

[0140] Correspondingly, such as Figure 3 As shown, the present invention provides a system using the above-mentioned method for treating heavy metals and impurity ions in secondary aluminum ash, comprising:

[0141] A hydrolysis reaction unit 1 for hydrolyzing the secondary aluminum ash;

[0142] A primary washing kettle 2 connected to the hydrolysis reaction unit 1 for washing the hydrolysis slurry solid phase obtained after hydrolysis and pressure filtration;

[0143] A secondary washing tank 3 connected to the primary washing tank 2 for washing the first solid phase obtained after washing in the primary washing tank;

[0144] A tertiary washing tank 4 connected to the secondary washing tank 3 for washing the second solid phase obtained after washing in the secondary washing tank; and

[0145] A tracer ion detection unit 5 is used to detect the content of heavy metals and impurity ions in the first solid phase, the second solid phase and / or the third solid phase.

[0146] like Figure 4 As shown, the first-stage washing kettle, the second-stage washing kettle and the third-stage washing kettle all include a washing kettle body 100, the washing kettle body 100 includes 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, and the power unit 90 includes a motor 91 and a reducer 92;

[0147] 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 eddy current 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.

[0148] 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 .

[0149] 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.

[0150] The present invention is further described below with specific implementations

[0151] Example 1

[0152] 1. 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 18% water. The solid phase after filtration is sent to a washing kettle for water washing.

[0153] 2. Set the solid-liquid ratio (mass ratio) in the washing kettle to 1:3.4, inject the first washing liquid into the first washing kettle, and the liquid level reaches 55% of the internal height of the washing kettle. The first washing liquid comes from the second liquid phase after the mud is filtered out of the outlet of the second washing kettle.

[0154] 3. Put the solid phase of the hydrolyzed mud after filter pressing into the first-stage washing kettle. The amount of the solid phase is determined according to the amount of washing liquid and the predetermined liquid-solid ratio.

[0155] 4. Turn on the agitator and the ultrasonic generator for washing. The agitator speed is 55r / min and the ultrasonic frequency is 40kHz.

[0156] 5. Introduce CO2 into the primary washing kettle until the pH of the washing liquid reaches 6.5.

[0157] 6. Add sulfuric acid into the primary washing kettle until the pH of the washing liquid reaches 3.

[0158] 7. Start washing for 18 minutes. Select Cl － ions were used as tracer ions and samples were taken at 5-min intervals to test the tracer ion content. － When the ion content changes by less than 10%, washing is completed.

[0159] 8. After washing, the mud in the first-stage washing kettle is pumped into the filter press for solid-liquid separation.

[0160] The first solid phase enters the secondary washing kettle for further washing, and the first liquid phase is used for secondary aluminum ash hydrolysis.

[0161] 9. Inject the second washing liquid into the secondary washing kettle until 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 filtered out of the tertiary washing kettle outlet.

[0162] 10. Put the first solid phase after filter pressing into the secondary washing kettle, and the amount of the first solid phase is determined according to the predetermined liquid-solid ratio.

[0163] 11. Turn on the agitator and ultrasonic generator for washing. The agitator speed is 55r / min and the ultrasonic frequency is 40kHz.

[0164] 12. Add sulfuric acid into the washing kettle until the pH of the washing liquid reaches 2.

[0165] 13. Start washing for 22 minutes. Select Cl － Ions were used as tracer ions and samples were taken at 5-min intervals to test Cl － When the change of tracer ion content between two times is less than 10%, washing is finished.

[0166] 14. 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.

[0167] 15. Inject the third washing liquid into the tertiary washing kettle until the liquid level reaches 55% of the internal height of the washing kettle. The third washing liquid in the tertiary washing kettle is clean water.

[0168] 16. The second solid phase of the secondary washing kettle after pressure filtration is placed into the tertiary washing kettle. The amount of the second solid phase is determined according to a predetermined liquid-solid ratio.

[0169] 17. Turn on the agitator and ultrasonic generator for washing. The agitator speed is 55r / min and the ultrasonic frequency is 40kHz.

[0170] 18. Add calcium hydroxide to the washing kettle until the pH is 8.

[0171] 19. Start washing for 22 minutes. Select Cl － Ions were used as tracer ions and samples were taken at 5-min intervals to test Cl － When the change of tracer ion content between two times is less than 10%, washing is finished.

[0172] 20. 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.

[0173] 21. Check the content of heavy metals and impurity ions. If they meet the specified standards, washing is completed. The solid phase obtained in this embodiment (i.e., the third solid phase) can be reused as concrete material.

[0174] Example 2

[0175] 1. 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.

[0176] 2. Set the solid-liquid ratio (mass ratio) in the washing kettle to 1:4.2, inject the first washing liquid into the first washing kettle, and the liquid level reaches 60% of the internal height of the washing kettle. The first washing liquid comes from the second liquid phase after the mud is filtered out of the outlet of the second washing kettle.

[0177] 3. Put the solid phase of the hydrolyzed mud after filter pressing into the first-stage washing kettle. The amount of the solid phase is determined according to the amount of washing liquid and the predetermined liquid-solid ratio.

[0178] 4. Turn on the agitator and the ultrasonic generator for washing. The agitator speed is 60r / min and the ultrasonic frequency is 60kHz.

[0179] 5. Introduce CO2 into the primary washing kettle until the pH of the washing liquid reaches 6.8.

[0180] 6. Add nitric acid into the primary washing kettle until the pH of the washing liquid reaches 3.5.

[0181] 7. Start washing for 25 minutes. Select Cl － ions were used as tracer ions and samples were taken at 5-min intervals to test the tracer ion content. － When the ion content changes by less than 8%, the washing is finished.

[0182] 8. After washing, the mud in the first-stage washing kettle is pumped into the filter press for solid-liquid separation.

[0183] The first solid phase enters the secondary washing kettle for further washing, and the first liquid phase is used for secondary aluminum ash hydrolysis.

[0184] 9. Inject the second washing liquid into the secondary washing kettle until 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.

[0185] 10. Put the first solid phase after filter pressing into the secondary washing kettle, and the amount of the first solid phase is determined according to the predetermined liquid-solid ratio.

[0186] 11. Turn on the agitator and the ultrasonic generator for washing. The agitator speed is 60r / min and the ultrasonic frequency is 60kHz.

[0187] 12. Add nitric acid into the washing kettle until the pH of the washing liquid reaches 2.5.

[0188] 13. Start washing for 28 minutes. Select Cl － Ions were used as tracer ions and samples were taken at 5-min intervals to test Cl － When the change of tracer ion content between two times is less than 8%, washing is finished.

[0189] 14. 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.

[0190] 15. Inject the third washing liquid into the tertiary washing kettle until the liquid level reaches 60% of the internal height of the washing kettle. The third washing liquid in the tertiary washing kettle is clean water.

[0191] 16. The second solid phase of the secondary washing kettle after pressure filtration is placed into the tertiary washing kettle. The amount of the second solid phase is determined according to a predetermined liquid-solid ratio.

[0192] 17. Turn on the agitator and ultrasonic generator for washing. The agitator speed is 60r / min and the ultrasonic frequency is 60kH.

[0193] 18. Add calcium hydroxide to the washing kettle until the pH is 9.

[0194] 19. Start washing for 25 minutes. Select Cl － Ions were used as tracer ions and samples were taken at 5-min intervals to test Cl － When the change of tracer ion content between two times is less than 8%, washing is finished.

[0195] 20. 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.

[0196] 21. Check the content of heavy metals and impurity ions in the third solid phase. If it meets the specified standards, the washing is completed.

[0197] The solid phase (ie, the third solid phase) obtained in this embodiment can be reused as a concrete material.

[0198] Example 3

[0199] 1. 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.

[0200] 2. Set the solid-liquid ratio (mass ratio) in the washing kettle to 1:5, inject the first washing liquid into the first washing kettle, and the liquid level reaches 65% of the internal height of the washing kettle. The first washing liquid comes from the second liquid phase after the mud is filtered out of the outlet of the second washing kettle.

[0201] 3. Put the solid phase of the hydrolyzed mud after filter pressing into the first-stage washing kettle. The amount of the solid phase is determined according to the amount of washing liquid and the predetermined liquid-solid ratio.

[0202] 4. Turn on the agitator and the ultrasonic generator for washing. The agitator speed is 60r / min and the ultrasonic frequency is 35kHz.

[0203] 5. Introduce CO2 into the primary washing kettle until the pH of the washing liquid reaches 6.2.

[0204] 6. Add nitric acid into the primary washing kettle until the pH of the washing liquid reaches 3.8.

[0205] 7. Start washing for 32 minutes. Select Cr as the tracer ion, take samples at 7-minute intervals, and check the tracer ion content. When the change in Cr content between two adjacent times is less than 5%, the washing is finished.

[0206] 8. After washing, the mud in the first-stage washing kettle is pumped into the filter press for solid-liquid separation.

[0207] The first solid phase enters the secondary washing kettle for further washing, and the first liquid phase is used for secondary aluminum ash hydrolysis.

[0208] 9. Inject the second washing liquid into the secondary washing kettle until 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 filtered out of the tertiary washing kettle outlet.

[0209] 10. Put the first solid phase after filter pressing into the secondary washing kettle, and the amount of the first solid phase is determined according to the predetermined liquid-solid ratio.

[0210] 11. Turn on the agitator and ultrasonic generator for washing. The agitator speed is 60r / min and the ultrasonic frequency is 35kHz.

[0211] 12. Add sulfuric acid into the washing kettle until the pH of the washing liquid reaches 3.2.

[0212] 13. Start washing for 28 minutes. Select Cr as the tracer ion, take samples at 7-minute intervals, and check the tracer ion content. When the change in Cr content between two adjacent times is less than 5%, the washing is finished.

[0213] 14. 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.

[0214] 15. Inject the third washing liquid into the tertiary washing kettle until the liquid level reaches 65% of the internal height of the washing kettle. The third washing liquid in the tertiary washing kettle is clean water.

[0215] 16. The second solid phase of the secondary washing kettle after pressure filtration is placed into the tertiary washing kettle. The amount of the second solid phase is determined according to a predetermined liquid-solid ratio.

[0216] 17. Turn on the agitator and ultrasonic generator for washing. The agitator speed is 55r / min and the ultrasonic frequency is 35kHz.

[0217] 18. Add carbide slag to the washing kettle until the pH reaches 10.

[0218] 19. Start washing for 28 minutes. Select Cr as the tracer ion and take samples at 7-minute intervals to check the tracer ion content. When the change in Cr content between two adjacent samples is less than 5%, the washing is finished.

[0219] 20. 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.

[0220] 21. Check the content of heavy metals and impurity ions in the third solid phase. If it meets the specified standards, the washing is completed.

[0221] The solid phase (ie, the third solid phase) obtained in this embodiment can be reused as a concrete material.

[0222] Example 4

[0223] 1. 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.

[0224] 2. Set the solid-liquid ratio (mass ratio) in the washing kettle to 1:6, inject the first washing liquid into the first 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 filtered out of the outlet of the second washing kettle.

[0225] 3. Put the solid phase of the hydrolyzed mud after filter pressing into the first-stage washing kettle. The amount of the solid phase is determined according to the amount of washing liquid and the predetermined liquid-solid ratio.

[0226] 4. Turn on the agitator and the ultrasonic generator for washing. The agitator speed is 65r / min and the ultrasonic frequency is 40kHz.

[0227] 5. Introduce CO2 into the primary washing kettle until the pH of the washing liquid reaches 6.2.

[0228] 6. Add a mixture of acetic acid and oxalic acid into the primary washing kettle until the pH of the washing liquid reaches 4.2.

[0229] 7. Start washing for 20 minutes. Select K + ions were used as tracer ions, and samples were taken at 6-min intervals to test the tracer ion content. + When the ion content changes by less than 10%, washing is completed.

[0230] 8. After washing, the mud in the first-stage washing kettle is pumped into the filter press for solid-liquid separation.

[0231] The first solid phase enters the secondary washing kettle for further washing, and the first liquid phase is used for secondary aluminum ash hydrolysis.

[0232] 9. Inject the second washing liquid into the secondary washing kettle until 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 filtered out of the tertiary washing kettle outlet.

[0233] 10. Put the first solid phase after filter pressing into the secondary washing kettle, and the amount of the first solid phase is determined according to the predetermined liquid-solid ratio.

[0234] 11. Turn on the agitator and ultrasonic generator for washing. The agitator speed is 65r / min and the ultrasonic frequency is 40kHz.

[0235] 12. Add a mixture of acetic acid and oxalic acid into the washing kettle until the pH of the washing liquid reaches 3.2.

[0236] 13. Start washing, the washing time is 28 minutes. Select K + ions were used as tracer ions, and samples were taken at 6-min intervals to test the tracer ion content. + When the ion content changes by less than 10%, washing is completed.

[0237] 14. 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.

[0238] 15. Inject the third washing liquid into the tertiary washing kettle until the liquid level reaches 70% of the internal height of the washing kettle. The third washing liquid in the tertiary washing kettle is clean water.

[0239] 16. The second solid phase of the secondary washing kettle after pressure filtration is placed into the tertiary washing kettle. The amount of the second solid phase is determined according to a predetermined liquid-solid ratio.

[0240] 17. Turn on the agitator and ultrasonic generator for washing. The agitator speed is 55r / min and the ultrasonic frequency is 40kHz.

[0241] 18. Add carbide slag to the washing kettle until the pH reaches 10.

[0242] 19. Start washing for 25 minutes. Select K + ions were used as tracer ions, and samples were taken at 6-min intervals to test the tracer ion content. + When the ion content changes by less than 10%, washing is completed.

[0243] 20. 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.

[0244] 21. Check the content of heavy metals and impurity ions in the third solid phase. If it meets the specified standards, the washing is completed.

[0245] The solid phase (ie, the third solid phase) obtained in this embodiment can be reused as a concrete material.

[0246] 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 treating heavy metals and impurity ions in secondary aluminum ash, characterized in that: include: The secondary aluminum ash is subjected to a hydrolysis reaction and then filtered to obtain a hydrolysis slurry solid phase; The hydrolysis slurry solid phase is washed multiple times, and in each washing, the slurry from the previous washing is subjected to solid-liquid separation to obtain a solid phase and a liquid phase; The treatment of the solid phase includes: mixing a washing liquid in the solid phase, adjusting the pH value and washing, and measuring the content of heavy metals and impurity ions after washing; The treatment of the liquid phase includes: collecting the liquid phase after each solid-liquid separation, dissolving carbon dioxide in the liquid phase and / or introducing an acidic solution to be used as a washing liquid for the previous solid phase treatment.

2. The method for treating heavy metals and impurity ions in secondary aluminum ash according to claim 1, characterized in that: include: The secondary aluminum ash is subjected to a hydrolysis reaction and then filtered to obtain a hydrolysis slurry solid phase; The hydrolysis slurry solid phase is washed at least three times, and in the first washing, the second washing, and the third washing, the slurry of the previous washing is subjected to solid-liquid separation to obtain a solid phase and a liquid phase; The treatment of the solid phase includes: mixing a washing liquid in the solid phase, adjusting the pH value and washing, and measuring the content of heavy metals and impurity ions after washing; The treatment of the liquid phase includes: collecting the liquid phase after solid-liquid separation in the first washing, the second washing, and the third washing, dissolving carbon dioxide and / or passing an acidic solution into the liquid phase, and using it as a washing liquid for solid phase treatment in the first washing and the second washing.

3. The method for treating heavy metals and impurity ions in secondary aluminum ash according to claim 1 or 2, characterized in that: include: The secondary aluminum ash is subjected to a hydrolysis reaction and then filtered to obtain a hydrolysis slurry solid phase; Injecting a first washing liquid into the first washing kettle and sending the hydrolyzed mud solid phase into the washing kettle, wherein the first washing liquid comes from the second liquid phase after the mud 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; 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; Passing an alkaline solution into the third-stage washing kettle until the pH of the washing solution 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 standard, the washing is completed. If it does not meet the specified standard, the washing of the three-stage washing kettle is repeated.

4. The method for treating heavy metals and impurity ions in secondary aluminum ash according to claim 3, 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 height 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.

5. The method for treating heavy metals and impurity ions in secondary aluminum ash according to claim 3, characterized in that: 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 solution is one or a combination of calcium hydroxide, sodium hydroxide and carbide slag, and the third preset pH value is 7-12.

6. The method for treating heavy metals and impurity ions in secondary aluminum ash according to claim 3, characterized in that: The conditions for determining the end of each wash include: One or more heavy metal or impurity ions are selected as tracer ions and sampling is performed at preset intervals; 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; Wherein, the ion preset value is 5-10%; The heavy metals in the secondary aluminum ash 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 .

7. The method for treating heavy metals and impurity ions in secondary aluminum ash according to claim 3, characterized in that: 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.

8. The method for treating heavy metals and impurity ions in secondary aluminum ash according to claim 1, characterized in that: The hydrolysis reaction of the secondary aluminum ash and the subsequent pressure filtration to obtain the hydrolysis slurry solid phase comprises: The secondary aluminum ash is subjected to a hydrolysis reaction to obtain a slurry; The hydrolyzed mud is sent to a filter press for solid-liquid separation, and a hydrolyzed mud solid phase is obtained after filtration. The water content of the hydrolyzed mud solid phase is 15-25%.

9. A system using the method for treating heavy metals and impurity ions in secondary aluminum ash according to any one of claims 1 to 8, characterized in that: include: A hydrolysis reaction unit for hydrolyzing the secondary aluminum ash; A primary washing kettle connected to the hydrolysis reaction unit for washing the hydrolyzed sludge solid phase obtained after hydrolysis; A secondary washing kettle connected to the primary washing kettle for washing the first solid phase obtained after washing in the primary washing kettle; A tertiary washing kettle connected to the secondary washing kettle for washing the second solid phase obtained after washing in the secondary washing kettle; as well as A tracer ion detection unit for detecting the content of heavy metals and impurity ions in the first solid phase, the second solid phase and / or the third solid phase.

10. The system according to claim 9, characterized in that The first-stage washing kettle, the second-stage washing kettle and the third-stage washing kettle all include a washing kettle body, which includes a kettle body, a feeding port and a water inlet arranged at the upper part of the kettle body, a discharge valve and a mud pump arranged at the lower part of the kettle body, an ultrasonic and spoiler plate, an agitator and an aeration pipe arranged inside the kettle body, and an electric power unit for controlling the rotation of the agitator; The ultrasonic and spoiler plate is arranged on the inner wall of the kettle body; The aeration pipe is arranged at the bottom of the kettle body, and comprises an aeration main pipe and an annular aeration pipe. The annular aeration pipe comprises a plurality of annular aeration sub-pipes arranged in concentric circles, and the plurality of annular aeration sub-pipes are connected to the aeration main pipe.

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