阅读说明：本技术 一种控制粉煤灰和/或镁渣、镁渣基充填膏体氨释放的制备方法与装置 (Preparation method and device for controlling ammonia release of fly ash and/or magnesium slag and magnesium slag-based filling paste ) 是由 邵小平 田创 徐宝娃 李龙清 任武昂 唐仁龙 李超 于 2021-09-17 设计创作，主要内容包括：一种控制粉煤灰、镁渣基充填膏体氨释放的制备方法,首先单独将粉煤灰通过高速水力剪切搅拌制备成低浓度的浆液；随后将制备好的浆液送入吹脱塔自上而下与空气进行逆流接触使溶于浆液中的氨转移至气相；接着对经过氨吹脱的低浓度粉煤灰和/或镁渣浆液进行静置,上清液回流至浆液配制单元重新利用；最后将静置粉煤灰和/或镁渣浆液池底部符合配制要求的高含固率浆体与充填膏体的其余配比原料进行复配,形成最终的粉煤灰和/或镁渣基充填膏体。本发明可以抑制粉煤灰基膏体充填井下氨气释放,为解决大掺量粉煤灰基充填膏体在煤矿高效开采应用过程中的环境问题提供新的途径。(A preparation method for controlling ammonia release of fly ash and magnesium slag-based filling paste comprises the following steps of firstly, independently preparing fly ash into low-concentration slurry through high-speed hydraulic shearing and stirring; then the prepared slurry is sent into a stripping tower to be in countercurrent contact with air from top to bottom so that ammonia dissolved in the slurry is transferred to a gas phase; then standing the low-concentration fly ash and/or magnesium slag slurry subjected to ammonia stripping, and refluxing the supernatant to a slurry preparation unit for reuse; and finally, compounding the high-solid-content slurry meeting the preparation requirement at the bottom of the standing fly ash and/or magnesium slag slurry pool with the rest proportioning raw materials of the filling paste to form the final fly ash and/or magnesium slag-based filling paste. The invention can inhibit the release of ammonia gas under the coal ash-based paste filling well, and provides a new way for solving the environmental problem of the coal ash-based filling paste with large mixing amount in the high-efficiency mining application process of the coal mine.)

1. A preparation method for controlling ammonia release of fly ash and/or magnesium slag and magnesium slag-based filling paste is characterized by comprising the following steps:

the first step is as follows: independently shearing and stirring the fly ash and/or the magnesium slag in the filling paste ingredient by using water power to prepare slurry with the solid content of 10-20%;

the second step is that: feeding the prepared slurry into a stripping tower to perform countercurrent contact with air from top to bottom, so that ammonia dissolved in the slurry is transferred to a gas phase;

the third step: concentrating the slurry after ammonia stripping;

the fourth step: and compounding the concentrated slurry with the rest components in the filling paste ingredient to form the final fly ash and/or magnesium slag-based filling paste.

2. The controlled fly ash of claim 1And/or the preparation method of the ammonia release of the magnesium slag and magnesium slag base filling paste is characterized in that the hydraulic shearing stirring is to form high-speed circulation in water for preparing the slurry through a plug flow stirrer, the stirring speed is 300-500 rad/min, the diameter of an impeller is 1/3-1/2 of the diameter of a stirring barrel, then the slurry is sent downwards to a stripping tower, the through-flow quantity of the slurry in the tower is 2-3 m³/26min·m²The gas-water ratio is 10-20: 1.

3. The method for preparing the ammonia-release-controlled fly ash and/or magnesium slag-based filling paste according to claim 1, wherein the solid flux in the concentration process is 100-200 kg/min-m²And after the concentration is finished, the solid content of the slurry is increased from 10-20% to 45-65%, and the supernatant liquid flows back to the slurry preparation unit for reuse.

4. The method for preparing the ammonia release control fly ash and/or magnesium slag and magnesium slag-based filling paste according to claim 3, wherein the reflux amount of the supernatant is calculated according to the following formula:

M_{amount of reflux}＝M_{Total amount of deaminated slurry}×(R_{High solid content}-R_{Low solid content})

In the formula: m_{Amount of reflux}The flow rate of supernatant liquid reflux, M_{Total mass of deamination slurry}The total mass of the slurry after deamination, R_{High solid content}For high solid content of deamination slurry, R_{Low solid content}The deamination slurry has low solid content.

5. The preparation method for controlling ammonia release of the fly ash and/or magnesium slag and magnesium slag-based filling paste according to claim 1, wherein the ingredients of the filling paste are aggregate, the mass ratio of the fly ash and/or magnesium slag to the cement is 2-3: 6-7: 0.5-1, the solid content of the obtained fly ash and/or magnesium slag-based filling paste is 76-85%, and when the fly ash and the magnesium slag are adopted, the proportion of the fly ash and the magnesium slag is arbitrary.

6. A preparation method and a device for controlling the release of ammonia in fly ash and/or magnesium slag and magnesium slag-based filling paste are characterized by comprising the following steps:

the slurry stirring barrel (I) is used for preparing slurry with the solid content of 10-20% by shearing and stirring the fly ash and/or the magnesium slag through water power;

the slurry ammonia stripping tower (II) is provided with a slurry distributor (15) at the top and a slurry circulating pool (7) at the bottom, the slurry distributor (15) is connected with the slurry stirring barrel (I), slurry is sent out downwards and is in countercurrent contact with air, ammonia dissolved in the slurry is transferred to a gas phase, and the slurry subjected to ammonia stripping enters the slurry circulating pool (7);

the concentration tank (III) is connected with the slurry circulating tank (7) and is used for concentrating the slurry subjected to ammonia stripping;

and the paste stirring barrel (IV) is connected with the concentration tank (III) and is used for compounding the concentrated serous fluid with the rest components in the filling paste ingredient to form the final fly ash and/or magnesium slag-based filling paste.

7. The device for preparing the ammonia release-controlling fly ash and/or magnesium slag-based filling paste according to claim 6, it is characterized in that a slurry outlet (4) of the slurry stirring barrel (I) is connected with a slurry distributor (15) through a pipeline with a low-concentration slurry delivery pump (5), an upper layer dispersion net (14), a middle layer redistribution device (13) and a lower layer dispersion net (12) are sequentially arranged in the slurry ammonia stripping tower (II) from top to bottom, the lower outlet of the slurry circulating tank (7) is connected with an inlet of a tee joint (16), one outlet of the tee joint (16) is connected to a slurry distributor (15) through a pipeline with a circulating pump (18), the other outlet of the tee joint is connected to a concentration tank (III) through a pipeline with a valve II (17), and a bottom discharge hole (22) of the concentration tank (III) is connected to a paste stirring barrel (IV) through a pipeline with a concentrated slurry conveying pump (23).

8. The device for preparing the ammonia-release-controlling fly ash and/or magnesium slag-based filling paste according to claim 7, wherein the bottom of the middle-layer redistribution device (13) is a flat plate with uniform openings, the side surface of the middle-layer redistribution device is an inclined surface, the top edge of the side surface of the middle-layer redistribution device is installed on the inner wall of the slurry ammonia stripping tower (II) and is arranged in the middle of the tower body, the upper-layer dispersion net (14) and the lower-layer dispersion net (12) have the same structure and are flat plates with a plurality of circular holes with the same size, and the circular holes are uniformly arranged into concentric rings to realize the uniform gas distribution function.

9. The device for preparing the ammonia-release control fly ash and/or magnesium slag and magnesium slag-based filling paste according to claim 7, wherein a first exhaust port (3) of the slurry stirring barrel (I) is connected with an air inlet (9) of the slurry ammonia stripping tower (II) through a pipeline with a first draught fan (21), a second exhaust port (26) of the paste stirring barrel (IV) is connected with the air inlet (9) of the slurry ammonia stripping tower (II) through a pipeline with a second draught fan (27), an air inlet (11) of the slurry ammonia stripping tower (II) is connected with a fan (10), and a feeding port (1) of the slurry stirring barrel (I) is connected with the supernatant of the concentration tank (III) through a pipeline with a supernatant delivery pump (20).

10. The device for preparing the ammonia-release-controlled fly ash and/or magnesium slag-based filling paste according to claim 9, wherein the diameter-height ratio of the slurry ammonia stripping tower (II) is 1: 10-15, the gas ascending velocity in the tower is 3-6 m/s, the low-concentration slurry delivery pump (5) adopts a centrifugal slurry pump, the lift is the height of the slurry ammonia stripping tower (II) plus a 10m safe head, the circulating pump (18) adopts a centrifugal slurry pump, the circulating amount is 100-200% of the liquid inlet amount, the lift is the height of the slurry ammonia stripping tower (II) plus a 10m safe head, the concentrated slurry delivery pump (23) adopts a screw pump, the flow is 1/6-1/4 of the flow of the low-concentration slurry delivery pump (5), the stirring time in the paste stirring barrel (IV) is 8-15 min, and the stirring speed is 20-50 rad/min, the air pressure of the fan (10) is 20-30 kPa, the air quantity is 10-20 times of the slurry flow, the first induced draft fan (21) and the second induced draft fan (27) control the air exchange times of the slurry preparation reactor to be 20-30 times/h, and the negative pressure is maintained at-10 to-20 kPa.

Technical Field

The invention belongs to the technical field of coal mining, and particularly relates to a preparation method and a device for controlling ammonia release of fly ash and/or magnesium slag and magnesium slag-based filling paste.

Background

The solid waste of coal-fired power plants is mainly fly ash, which is generally silver gray or gray, the fly ash with darker color has higher carbon content and larger proportion of coarse particles. In recent years, the amount of the fly ash used for mine filling is remarkably increased, however, the fly ash obtained after denitration in a coal-fired power plant contains ammonia nitrogen substances due to the existing denitration technology, and the ammonia nitrogen substances mainly exist in the form of ammonium bisulfate or ammonium sulfate or ammonia gas adsorbed on the fly ash. The denitration coal ash is used as an admixture, ammonia nitrogen substances of the denitration coal ash are mainly released in the form of ammonia gas and are concentrated for 8 hours before stirring, a part of ammonia gas is dissipated near an underground filling working surface, and the underground space is relatively closed, so that the ammonia gas is enriched, the concentration is increased, the ventilation quality is lowered, and the working efficiency and the body health of filling operators are influenced. The other part of ammonia gas is added in the fly ash-based filler, so that the setting time of the cement is prolonged, and the strength is reduced. But at present, no mature and reliable method for controlling ammonia release of the fly ash-based paste exists.

Disclosure of Invention

The invention aims to provide a preparation method and a device for controlling ammonia release of a coal ash and/or magnesium slag and magnesium slag-based filling paste during denitration coal ash-based filling mining, and aims to prepare coal ash and/or magnesium slag slurry, convert ammonium ions in the coal ash and/or magnesium slag slurry into ammonia gas, blow off the ammonia gas in the slurry by using a blow-off tower, prepare the blown-off coal ash and/or magnesium slag slurry and other filling materials into a coal ash and/or magnesium slag-based filling material according to a certain ratio for underground filling, create a good working environment for coal ash and/or magnesium slag-based filling material filling and provide technical support for improving the strength of a filling body.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method for controlling ammonia release of fly ash and/or magnesium slag and magnesium slag-based filling paste comprises the following steps:

the first step is as follows: independently shearing and stirring the fly ash and/or the magnesium slag in the filling paste ingredient by using water power to prepare slurry with the solid content of 10-20%;

the second step is that: feeding the prepared slurry into a stripping tower to perform countercurrent contact with air from top to bottom, so that ammonia dissolved in the slurry is transferred to a gas phase;

the third step: concentrating the slurry after ammonia stripping;

the fourth step: and compounding the concentrated slurry with the rest components in the filling paste ingredient to form the final fly ash and/or magnesium slag-based filling paste.

Preferably, the hydraulic shear stirring is to form a high-speed circulation in the water for slurry preparation through a plug flow stirrer, so that the added fly ash and/or magnesium slag is rapidly and uniformly dispersed in the water, and the complete dissolution of ammonium ions adsorbed on the surface of the fly ash and/or magnesium slag is accelerated; the stirring speed is 300 to 500rad/min, and the diameter of the impeller is 1/3 to 1/2 of the diameter of the stirring barrel.

Preferably, in the second step, the slurry is pressurized by a pump from a circulating pool at the bottom of the stripping tower, lifted to a distributor at the top of the stripping tower and then sent downwards to the stripping tower, and the slurry in the stripping tower has the through-flow capacity of 2-3 m³/min·m²The gas-water ratio is 10-20: 1.

Preferably, theThe solid flux in the concentration process is 100-200 kg/min m²And after the concentration is finished, the solid content of the slurry is increased from 10-20% to 45-65%, and the supernatant liquid flows back to the slurry preparation unit for reuse.

Preferably, the specific solid content of the fly ash and/or magnesium slag slurry can be determined according to the solid content requirement of the finally compounded filling paste, and the solid content of the fly ash and/or magnesium slag slurry is realized by controlling the reflux amount of the supernatant; the reflux amount of the supernatant was calculated according to the following formula:

M_{amount of reflux}＝M_{Total amount of deaminated slurry}×(R_{High solid content}-R_{Low solid content})

In the formula: m_{Amount of reflux}The supernatant reflux water flow is kg; m_{Total mass of deamination slurry}Kg is the total mass of the slurry after deamination; r_{High solid content}Taking 45-65% of deamination slurry with high solid content; r_{Low solid content}10 to 20 percent of deamination slurry is taken for low solid content.

Preferably, the filling paste ingredients are aggregate, the mass ratio of the fly ash and/or magnesium slag to the cement is 2-3: 6-7: 0.5-1, the solid content of the obtained fly ash and/or magnesium slag-based filling paste is 76% -85%, and when the fly ash and the magnesium slag are adopted, the proportion of the fly ash and the magnesium slag is arbitrary.

The invention also provides a preparation method and a device for controlling the ammonia release of the fly ash and/or magnesium slag and magnesium slag-based filling paste, which comprise the following steps:

the slurry stirring barrel is used for preparing the fly ash and/or the magnesium slag into slurry with the solid content of 10-20% through hydraulic shearing and stirring;

the slurry ammonia stripping tower is provided with a slurry distributor at the top and a slurry circulating tank at the bottom, the slurry distributor is connected with a slurry stirring barrel, slurry is sent out downwards and is in countercurrent contact with air, ammonia dissolved in the slurry is transferred to a gas phase, and the slurry subjected to ammonia stripping enters the slurry circulating tank;

the concentration tank is connected with the slurry circulating tank and is used for concentrating the slurry subjected to ammonia stripping;

and the paste stirring barrel is connected with the concentration tank, and the concentrated slurry is compounded with the rest components in the ingredients of the filling paste to form the final fly ash and/or magnesium slag-based filling paste.

The thick liquids export of thick liquids agitator is through the tube coupling thick liquids distributor of taking low concentration thick liquids delivery pump, top-down sets gradually upper dispersion net, middle level redistribution device and lower floor's dispersion net in the thick liquids ammonia stripping tower, the three-way entry of thick liquids circulation tank lower part exit linkage, the three-way exit of the same way is through the tube coupling who takes the circulating pump to thick liquids distributor, and another way export is through the tube coupling who takes the valve to concentrated pond, and the bottom discharge mouth in concentrated pond is through the tube coupling who takes concentrated thick liquids delivery pump to lotion agitator.

The bottom of the middle-layer redistribution device is a flat plate with uniform holes, the side surface of the middle-layer redistribution device is an inclined surface, the top edge of the side surface of the middle-layer redistribution device is arranged on the inner wall of the slurry ammonia stripping tower and is arranged in the middle of the tower body, the upper-layer dispersion net and the lower-layer dispersion net are the same in structure and are flat plates with round holes of the same size, and the round holes are uniformly arranged into concentric rings to realize the uniform gas distribution function.

The air outlet I of the slurry mixing barrel is connected with the air inlet of the slurry ammonia stripping tower through a pipeline with a draught fan I, the air outlet II of the paste mixing barrel is connected with the air inlet of the slurry ammonia stripping tower through a pipeline with a draught fan II, the air inlet of the slurry ammonia stripping tower is connected with a fan, and the feeding port of the slurry mixing barrel is connected with the supernatant of the concentration tank through a pipeline with a supernatant conveying pump.

The diameter-height ratio of the slurry ammonia stripping tower is 1: 10-15, the ascending flow velocity of gas in the tower is 3-6 m/s, the low-concentration slurry delivery pump adopts a centrifugal slurry pump, the lift is the height of the slurry ammonia stripping tower plus a 10m safety head, the circulating pump adopts a centrifugal slurry pump, the circulating flow is 100-200% of liquid inlet flow, the lift is the height of the slurry ammonia stripping tower plus a 10m safety head, the concentrated slurry delivery pump adopts a screw pump, the flow is 1/6-1/4 of the low-concentration slurry delivery pump flow, the stirring time in the paste stirring barrel is 8-15 min, the stirring speed is 20-50 rad/min, the wind pressure of the fan is 20-30 kPa, the wind quantity is 10-20 times of slurry flow, and the first and second induced draft fans control the ventilation times of the slurry preparation reactors (the slurry stirring barrel I and the paste stirring barrel IV) to be 20-30 times/h, the negative pressure is maintained between-10 kPa and-20 kPa.

Compared with the prior art, the invention has the beneficial effects that:

1. the coal ash and/or magnesium slag-based paste can be effectively released to fill the underground ammonia gas, and a basic basis is provided for guiding and solving the environmental problem of the coal ash and/or magnesium slag-based paste in the high-efficiency mining application process of the coal mine.

2. The residual ammonia content in the underground fly ash and/or magnesium slag-based filler can be simulated and detected.

3. The dust generated in the process of preparing the fly ash and/or magnesium slag-based paste filling material can be effectively treated.

4. The invention has the advantages of accurate detection, simple and convenient operation, wide application range and good social and economic benefits after popularization.

Drawings

FIG. 1 is a schematic view of the structure of a production apparatus of the present invention.

Detailed Description

The embodiments of the present invention will be described in detail below with reference to the drawings and examples.

The invention relates to a preparation method for controlling ammonia release of fly ash and/or magnesium slag and magnesium slag-based filling paste, which comprises the following steps:

the first step is as follows: and (3) independently shearing and stirring the fly ash in the filling paste ingredient by using water power to prepare slurry with the solid content of 10-20%.

The hydraulic shearing stirring is to form high-speed circulation in water for preparing slurry by a plug flow stirrer, so that the added fly ash is quickly and uniformly dispersed in the water, and the ammonium ions adsorbed on the surface of the fly ash are accelerated to be thoroughly dissolved; the stirring speed is 300 to 500rad/min, and the diameter of the impeller is 1/3 to 1/2 of the diameter of the stirring barrel.

The second step is that: the prepared slurry is sent into a stripping tower to be in countercurrent contact with air from top to bottom, so that ammonia dissolved in the slurry is transferred to a gas phase.

Specifically, the slurry is circulated from the bottom of the stripping towerPressurizing the pool by a pump, lifting the pool to a distributor at the top of a stripping tower, and then sending the pool downwards to a slurry ammonia stripping tower II, wherein the slurry overflowing amount in the tower is 2-3 m³/min·m²The gas-water ratio is 10-20: 1.

The third step: and (4) concentrating the slurry subjected to ammonia stripping, and refluxing the supernatant to the first step for recycling.

Specifically, the solid flux in the concentration process is 100-200 kg/min m²And after the concentration is finished, the solid content of the slurry is increased from 10-20% to 45-65%, and the supernatant liquid flows back to the slurry preparation unit for reuse.

The concrete solid content of the fly ash slurry is determined according to the solid content requirement of the finally compounded filling paste, and the concrete solid content can be realized by controlling the reflux quantity of the supernatant, and the reflux quantity of the supernatant is calculated according to the following formula:

M_{amount of reflux}＝M_{Total amount of deaminated slurry}×(R_{High solid content}-R_{Low solid content})

In the formula: m_{Amount of reflux}The supernatant reflux water flow is kg; m_{Total mass of deamination slurry}Kg is the total mass of the slurry after deamination; r_{High solid content}Taking 45-65% of deamination slurry with high solid content; r_{Low solid content}10 to 20 percent of deamination slurry is taken for low solid content.

The fourth step: and compounding the concentrated slurry with the rest components in the filling paste ingredient to form the final fly ash-based filling paste.

The filling paste ingredient is aggregate, the mass ratio of the fly ash to the cement is 2-3: 6-7: 0.5-1, and the solid content of the obtained fly ash-based filling paste is 76-85%.

The present invention also provides a corresponding manufacturing apparatus, as shown in fig. 1, comprising:

and a slurry stirring barrel I, namely preparing the fly ash into slurry with the solid content of 10-20% by hydraulic shearing and stirring. A high-speed stirring pump I2 is arranged in a barrel, a feeding port 1 and an exhaust port I3 are arranged at the top of the barrel, and a slurry outlet 4 is arranged at the bottom of the barrel.

The slurry ammonia stripping tower II is provided with a slurry distributor 15 at the top and a slurry circulating tank 7 at the bottom, an upper layer dispersing net 14, a middle layer redistributing device 13 and a lower layer dispersing net 12 are sequentially arranged in the tower from top to bottom, a tower body is arranged between the lower layer dispersing net 12 and the slurry circulating tank 7 and is provided with an air inlet 9 and an air inlet 11, and the air inlet 11 can be arranged at the upper part of the air inlet 9. The slurry distributor 15 adopts a spray head structure to uniformly spray and disperse the absorption liquid. The first exhaust port 3 is connected with the air inlet 9 of the slurry ammonia stripping tower II through a pipeline with a first draught fan 21, the second exhaust port 26 is connected with the air inlet 9 of the slurry ammonia stripping tower II through a pipeline with a second draught fan 27, and the air inlet 11 is connected with a fan 10. A slurry sampling hole 8 is arranged on the slurry circulating pool 7, and the outlet at the lower part of the slurry circulating pool is connected with the inlet of a tee 16. The slurry distributor 15 is connected with the slurry stirring barrel I, the slurry is sent out downwards and is in countercurrent contact with air, ammonia dissolved in the slurry is transferred to a gas phase, and the slurry subjected to ammonia stripping enters the slurry circulating tank 7.

And the concentration tank III is connected with the slurry circulation tank 7, the slurry subjected to ammonia stripping is concentrated, and the feeding port 1 is connected with the supernatant of the concentration tank III through a pipeline with a supernatant delivery pump 20.

And the paste stirring barrel IV is connected with the concentration tank III, and the concentrated serous fluid is compounded with the rest components in the filling paste ingredient to form the final fly ash-based filling paste.

The slurry outlet 4 is connected with a slurry distributor 15 through a pipeline with a low-concentration slurry delivery pump 5, one outlet of a tee joint 16 is connected with the slurry distributor 15 through a pipeline with a circulating pump 18, the other outlet of the tee joint is connected with a concentration tank III through a pipeline with a valve II 17, a bottom discharge port 22 of the concentration tank III is connected with a paste stirring barrel IV through a pipeline with a concentration slurry delivery pump 23, and the paste stirring barrel IV is provided with a high-speed stirring pump I25.

According to the structure, the slurry stirring barrel I conveys low-concentration slurry to a slurry distributor 15 in a slurry ammonia stripping tower II through a slurry outlet 4 and a pipeline with a low-concentration slurry conveying pump 5, the slurry falls from top to bottom and sequentially passes through an upper layer dispersing net 14, a middle layer redistributing device 13 and a lower layer dispersing net 12 and then enters a slurry circulating tank 7 at the bottom of the stripping tower, one path of slurry discharged out of the slurry circulating tank 7 returns to the slurry distributor 15 through the pipeline and a circulating pump 18, the other path of slurry is conveyed to a concentration tank III through the pipeline, the concentrated slurry in the concentration tank III is pumped into a paste stirring barrel IV from a bottom discharge port 22 through a concentrated slurry conveying pump 23, and the paste is stirred with other components to prepare paste.

The device comprises a slurry ammonia stripping tower II, a slurry mixing tank I, a slurry ammonia stripping tower II, a pipeline with a first induced draft fan 21, a pipeline with a second induced draft fan 27, a pipeline with a third induced draft fan 23, a pipeline with a third induced draft fan 27, a pipeline with a fourth induced draft fan 10, a pipeline with a third induced draft fan 20, a pipeline with a fifth induced draft fan 23, a pipeline with a fifth induced draft fan 20, a pipeline with a fifth induced draft fan 27, a pipeline with a fifth induced draft fan 23, a pipeline with a fifth induced draft fan 20, a pipeline with a fifth induced draft fan 23, a pipeline with a fifth induced draft fan 27, a pipeline with a fifth induced draft fan 2, a pipeline with a fifth induced draft fan, a pipeline with a pipeline and a pipeline.

The technological parameters adopted by the device can be as follows:

the diameter-height ratio of a slurry ammonia stripping tower II is 1: 10-15, the gas in the tower rises at the flow rate of 3-6 m/s, a centrifugal slurry pump is adopted as a low-concentration slurry delivery pump 5, the lift is the height of the slurry ammonia stripping tower II plus a 10m safe water head, a centrifugal slurry pump is adopted as a circulating pump 18, the circulating amount is 100-200% of liquid inlet amount, the lift is the height of the slurry ammonia stripping tower II plus a 10m safe water head, a screw pump is adopted as a concentrated slurry delivery pump 23, the flow is 1/6-1/4 of the flow of the low-concentration slurry delivery pump 5, the stirring time in a paste stirring barrel IV is 8-15 min, the stirring speed is 20-50 rad/min, the wind pressure of a fan 10 is 20-30 kPa, the wind amount is 10-20 times of slurry flow, a variable frequency motor can be adopted for real-time adjustment according to the stripping effect, and a first induced draft fan 21 and a second induced draft fan 27 control the ventilation frequency of a slurry preparation reactor to be 20-30 times/h, the negative pressure is maintained between-10 kPa and-20 kPa.

In the invention, the bottom of the middle layer redistributing device 13 is a flat plate with uniform holes, and the side surface is an inclined surface, thus forming a structure similar to a bowl. The top edge of the side surface of the tower body is arranged on the inner wall of the slurry ammonia stripping tower II and is approximately arranged in the middle of the tower body, and the function is to collect the absorption liquid on the tower wall again and then evenly distribute the absorption liquid again, so that the wall flow condition of the absorption liquid is reduced. The upper layer dispersing net 14 and the lower layer dispersing net 12 have the same structure and are flat plates with round holes of phi 3mm in the same size, and the round holes are uniformly arranged into concentric rings to realize the function of uniform gas distribution.

The liquid ammonia stripping device is started to meet the following principle: after the fly ash slurry is fully stirred, the fan 10 is started, the low-concentration slurry delivery pump 5 is started to enable the slurry to fall into the slurry circulating pool 7 from top to bottom through the slurry distributor 15 and in countercurrent contact with blown air, after the slurry in the slurry stirring barrel I is completely delivered into the slurry circulating pool 7, the low-concentration slurry delivery pump 5 is closed, and the circulating pump 18 is started to enable the slurry to fall into the slurry circulating pool 7 from top to bottom through the slurry distributor 15.

According to the stripping method based on the device, stripping liquid is stripped by positive pressure stripping, air is conveyed into the stripping tower through an air inlet 11 of the stripping tower II by a fan 10, the air is in countercurrent contact with the stripping liquid, and liquid-phase ammonia in the stripping liquid is separated into gas-phase ammonia through the blown air. The stripped ammonia gas is discharged from the top of the slurry ammonia stripping tower II, the stripping liquid flows into the bottom of the tower body from top to bottom, and then the absorption liquid is lifted to the liquid distributor 15 from the bottom of the tower body by using the circulating pump 18 for liquid redistribution.

The method comprises the following specific steps:

firstly, preparing fly ash slurry with low solid content: fly ash and water are added into a slurry stirring barrel I through a feed inlet 1 of the slurry stirring barrel I according to a certain proportion, a high-speed stirring pump I2 is started until the mixture is fully stirred, the high-speed stirring pump I2 is closed, the stirring is stopped, dust generated in the stirring process is conveyed to a slurry ammonia stripping tower II through a draught fan I21, and the dust is discharged after dust fall purification treatment.

Secondly, blowing off liquid ammonia from low-solid-content coal ash slurry: opening a second valve 4, starting a low-concentration slurry delivery pump 5, delivering the low-solid-content fly ash slurry in a slurry stirring barrel I into a slurry distributor 15, dropping the low-solid-content fly ash slurry into a slurry circulating pool 7 from top to bottom, starting a fan 10 after the low-solid-content fly ash slurry in the slurry stirring barrel I is completely delivered into the slurry circulating pool 7, delivering air into a slurry ammonia stripping tower II through an air inlet 11, starting a circulating pump 18 to enable the fly ash slurry to drop from top to bottom from the distributor 15, transferring ammonia gas to a gas phase by countercurrent contact with air in a stripping manner, reducing ammonia gas in the liquid phase, taking out the fly ash slurry through a slurry sampling hole 8 to detect the ammonia gas concentration, closing the valve to stop the circulating pump 18 when the ammonia gas concentration is reduced to a certain degree, and finally closing the fan 10.

Thirdly, improving the solid content of the fly ash slurry: and (3) opening a valve II 17 to enable the slurry to be input into a slurry concentration tank III from a slurry circulation tank 7, concentrating the slurry to obtain supernatant and high-solid-content fly ash slurry, pumping the supernatant into a slurry stirring barrel I for recycling through a pipeline of a supernatant delivery pump 20, and pumping the high-solid-content fly ash slurry into a paste stirring barrel IV through a concentrated slurry delivery pump 23.

Adding other materials to prepare paste: and adding the aggregate and the cement for preparing the paste into the paste stirring IV through a charging hole, uniformly stirring to prepare the required paste, conveying the dust generated in the stirring process into a slurry ammonia stripping tower II through a second induced draft fan 27, and discharging the dust after dust settling and purifying treatment.

In other embodiments of the invention, magnesium slag may be substituted for all or a portion of the fly ash.