CN113233798A

CN113233798A - Cement kiln dust/fly ash washing salt extraction treatment system and use method thereof

Info

Publication number: CN113233798A
Application number: CN202110556656.1A
Authority: CN
Inventors: 李叶青; 王加军; 刘喆; 曾璞; 魏茂
Original assignee: Huaxin Environmental Engineering Co ltd; Huaxin Cement Co Ltd
Current assignee: Huaxin Environmental Engineering Co ltd; Huaxin Cement Co Ltd
Priority date: 2021-05-21
Filing date: 2021-05-21
Publication date: 2021-08-10

Abstract

The invention relates to a cement kiln dust/fly ash washing salt extraction treatment system and a use method thereof, belonging to the technical field of solid waste and hazardous waste treatment. Comprises a metering discharge device, a multistage water washing stirring device, a filtrate pretreatment device and a multi-effect evaporation salt extraction device which are connected in sequence. And (3) metering and conveying kiln dust to a water washing stirring device, adding water, stirring, then feeding the mixture into a solid-liquid separation device, feeding the separated liquid-phase filtrate into a filtrate pretreatment system, feeding the filtrate into a multi-effect evaporator after the filtrate reaches an evaporation salt extraction standard, evaporating the filtrate to separate potassium salt out, drying the filtrate by using a centrifugal machine to obtain a potassium salt finished product, and recycling the solid-phase filter cake by using a cement kiln system.

Description

Cement kiln dust/fly ash washing salt extraction treatment system and use method thereof

Technical Field

The invention belongs to the technical field of solid waste and hazardous waste treatment, and particularly relates to a cement kiln ash/fly ash washing salt extraction treatment system and a use method thereof.

Background

Domestic garbage, domestic sludge and industrial waste are increasingly used as alternative fuels of cement kilns, but compared with traditional cement production raw materials, the alternative fuels contain higher chlorine, and the chlorine-containing waste is treated in the kiln in the cement clinker production process, so that the chlorine-containing waste is increased in the introduction amount of the chlorine in the kiln, and the corrosion to steel returned to a brick kiln, a preheater and a kiln tail dust remover is caused. The bypass air discharge is an effective means for reducing the chlorine content in the rotary kiln system, but the bypass ash containing a large amount of chlorine elements is difficult to be comprehensively utilized in the next step, so that a new disposal problem is brought.

Potassium is one of 3 nutrient elements determining the high yield of crops, more than 90% of the world potassium salt yield is used as a potassium fertilizer, and the demand is large.

The method has the advantages that the distribution characteristics of chlorine alkali in the bypass ash are combined, the resource-capable product KCl is extracted from the bypass ash, the content of chlorine in kiln ash/fly ash after KCl is extracted is greatly reduced, the kiln ash/fly ash is returned to the kiln for calcination and utilization, the problem of enrichment of Cl in a rotary cement kiln system in a synergistic treatment mode can be effectively solved, new pollution is not generated, and certain economic benefit can be obtained.

Disclosure of Invention

The invention aims to provide a cement kiln dust/fly ash washing salt extraction treatment system and a use method thereof.

Meanwhile, the system is also suitable for harmless treatment of the fly ash of the household garbage, and solves the problem that the fly ash with continuously rising yield is difficult to truly realize harmless resource treatment along with the rapid development of garbage incineration.

The invention adopts the following technical scheme:

a cement kiln dust/fly ash washing salt extraction treatment system comprises a metering discharge device, a multistage washing stirring device, a filtrate pretreatment device and a multi-effect evaporation salt extraction device which are sequentially connected.

Further, each stage of the multistage washing and stirring device comprises a washing and stirring tank and a solid-liquid separation device which are sequentially connected.

Further, the solid-liquid separation device is a vacuum drum filter. Can be separated to obtain powdery filter cakes which are convenient to transport. The powdery filter cake can be used as raw material to enter a cement kiln for reutilization.

Further, the filtrate pretreatment device comprises a shallow aeration tank, an inclined plate sedimentation tank with a dosing system and an ion exchanger which are sequentially connected, wherein an aeration pipeline arranged in the shallow aeration tank is connected with a cement kiln tail smoke discharge pipeline. The pretreatment device is used for removing calcium, high-valence metal ions and the like in the filtrate.

Further, the multi-effect evaporation salt extraction device comprises a plurality of effect evaporators which are connected in sequence. By controlling the parameters of each effect evaporator separately, separation of different classes of salts can be achieved.

Further, the multiple-effect evaporation salt extraction device further comprises a steam condensation water tank and a mother liquor treatment device, an outlet of the steam condensation water tank is connected with a washing stirring tank of the washing stirring device, and an outlet of the mother liquor treatment device is connected with the cement kiln decomposing furnace. And (4) condensing the steam, recycling the steam to a washing and stirring link, collecting the mother liquor, connecting the mother liquor to a cement kiln decomposing furnace, and burning the mother liquor in the kiln.

The use method of the cement kiln dust/fly ash washing salt extraction disposal system comprises the following steps: conveying kiln dust to a primary washing stirring tank through a metering and discharging device, adding water, stirring, then feeding into a primary solid-liquid separation device, feeding separated liquid-phase filtrate into a filtrate pretreatment device, feeding into a multi-effect evaporation salt extraction device after reaching the evaporation salt extraction standard, evaporating the filtrate to separate potassium salt out, and drying through a centrifugal machine to obtain a potassium salt finished product. The solid-phase filter cake is recycled by a cement kiln system.

And further, in the multistage washing and stirring device, kiln ash/fly ash at each stage is washed and stirred and then enters the solid-liquid separation device, the separated filter cake enters the next stage of washing and stirring device, the filtrate is recycled to the previous stage of washing and stirring tank, and the like.

The invention has the following beneficial effects:

1. after the cement kiln dust/fly ash is subjected to multistage water washing, almost all chlorine elements in a filter cake are washed out and then returned to a cement production system for use, so that the adverse effect of the chlorine elements on a kiln system and the quality of cement is reduced;

2. after washing the bypass ash water, carrying out solid-liquid separation by a vacuum filter, and obtaining continuously produced solid-phase ash slag and powdery materials with the water content of less than 40% without adding chemicals, thereby solving the problem that high-viscosity mud cakes are difficult to convey;

3. the kiln tail flue gas is used for carrying out decalcification and heavy metal removal pretreatment on the washing filtrate, so that the scaling of an evaporation system is slowed down, the content of amphoteric heavy metal ions such as Pb in the solution is reduced, and the medicament cost is saved. And meanwhile, when the system is stopped, the pH of liquid in each section of equipment can be controlled by using the kiln tail flue gas so as to reduce scaling.

4. The evaporation system adopts multiple-effect evaporation, the salt separation can be carried out by utilizing the solubility characteristic difference of various salts, the purity of the obtained potassium salt is high, and additional economic benefit can be generated.

5. The system fully depends on a cement kiln system to treat kiln ash/fly ash, and mother liquor and ash are sent into the cement kiln for recycling, so that secondary pollution is not generated, and harmless recycling treatment is realized.

Drawings

FIG. 1 is a process flow diagram of the disposal system of the present invention.

Detailed Description

The invention is further explained with reference to the accompanying drawings.

As shown in the figure, the cement kiln dust/fly ash washing salt extraction treatment system comprises a kiln dust washing stirring device, a solid-liquid separation device, a filtrate pretreatment device and a multi-effect evaporation salt extraction device which are sequentially connected. The kiln dust washing and stirring device comprises a kiln dust metering and discharging and washing stirring tank which are sequentially connected. And conveying the kiln dust to a water washing tank in a metering manner, adding water, stirring, and then allowing the kiln dust to enter a solid-liquid separation device. The water content of the filter cake obtained after the filtration by the vacuum filter is less than 40 percent, the chlorine content in the filter cake is reduced to below 1 percent, and the filter cake is powdery and is easy to be conveyed to a cement production system for recycling.

(2) The separated filtrate enters a filtrate pretreatment system and sequentially passes through a shallow aeration tank, an inclined plate sedimentation tank and an ion exchanger, waste flue gas at the tail of a cement kiln is introduced into the shallow aeration tank, the flue gas contains a large amount of CO2, the pH is controlled to be about 10, most calcium ions in the filtrate can be removed through sedimentation, and then a small amount of coagulant is added to continuously remove the residual Ca²⁺And other interfering ions are separated by an inclined plate sedimentation tank, enter an ion exchanger for further purification, and enter a multi-effect evaporator after reaching the standard of evaporation and salt extraction.

(3) And (3) evaporating the filtrate to separate out potassium salt, finally separating out crystal salt with the KCl purity higher than 94%, and drying by a centrifugal machine to obtain a potassium salt finished product. All steam evaporation and hot air required by drying come from the cement kiln system, so that high-efficiency cooperation with the cement kiln is realized.

(4) And the water vapor in the evaporation crystallization process is condensed and recycled to the washing unit, and the evaporated mother liquor is conveyed into a cement kiln for incineration treatment, so that no secondary pollution is ensured.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. The cement kiln dust/fly ash washing salt extraction treatment system is characterized in that: comprises a metering and discharging device, a multistage water washing and stirring device, a filtrate pretreatment device and a multi-effect evaporation salt extraction device which are connected in sequence.

2. The cement kiln dust/fly ash washing salt-extraction disposal system of claim 1, wherein: each stage in the multistage washing and stirring device comprises a washing and stirring tank and a solid-liquid separation device which are sequentially connected.

3. The cement kiln dust/fly ash washing salt-extraction disposal system of claim 2, wherein: the solid-liquid separation device is a vacuum rotary drum filter.

4. The cement kiln dust/fly ash washing salt-extraction disposal system of claim 3, wherein: the filtrate pretreatment device comprises a shallow aeration tank, an inclined plate sedimentation tank with a dosing system and an ion exchanger which are sequentially connected, wherein an aeration pipeline arranged in the shallow aeration tank is connected with a cement kiln tail smoke discharge pipeline.

5. The cement kiln dust/fly ash washing salt-extraction disposal system of claim 4, wherein: the multi-effect evaporation salt extraction device comprises a plurality of effect evaporators which are connected in sequence.

6. The cement kiln dust/fly ash washing salt-extraction disposal system of claim 5, wherein: the multi-effect evaporation salt extraction device further comprises a steam condensation water tank and a mother liquor disposal device, an outlet of the steam condensation water tank is connected with a washing stirring tank of the washing stirring device, and an outlet of the mother liquor disposal device is connected with the cement kiln decomposing furnace.

7. A method of using the cement kiln dust/fly ash water washing salt-leaching disposal system of any one of claims 1-6, wherein: the method comprises the following steps: conveying kiln dust to a primary washing stirring tank through a metering and discharging device, adding water, stirring, then feeding into a primary solid-liquid separation device, feeding separated liquid-phase filtrate into a filtrate pretreatment device, feeding into a multi-effect evaporation salt extraction device after reaching the evaporation salt extraction standard, evaporating the filtrate to separate potassium salt out, and drying through a centrifugal machine to obtain a potassium salt finished product. The solid-phase filter cake is recycled by a cement kiln system.

8. The use method of the cement kiln dust/fly ash washing salt-leaching disposal system according to claim 7, is characterized in that: in the multistage washing and stirring device, kiln ash/fly ash at each stage enters a solid-liquid separation device after being washed and stirred, separated filter cakes enter the next stage of washing and stirring device, filtrate is recycled to the previous stage of washing and stirring tank, and the like.