CN110124478B

CN110124478B - Denitration material prepared from nickel slag and suitable for cement kiln and denitration method thereof

Info

Publication number: CN110124478B
Application number: CN201910522084.8A
Authority: CN
Inventors: 崔素萍; 甘延玲; 刘振涛; 王亚丽; 马晓宇
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2019-06-17
Filing date: 2019-06-17
Publication date: 2022-04-22
Anticipated expiration: 2039-06-17
Also published as: CN110124478A

Abstract

A denitration material suitable for a cement kiln and a denitration method thereof are prepared by taking nickel slag as a raw material, and belong to the field of industrial kiln flue gas denitration. The porous denitration material is prepared by using nickel slag as a raw material and adopting a method of acid dissolution, alkali dropwise addition and pH adjustment precipitation. The preparation method adopts industrial waste residues as raw materials, saves cost, has simple process and really realizes resource utilization of the waste residues. The denitration rate of the denitration material in a high-temperature area (700 ℃ -1000 ℃) can reach more than 80%. The porous material and the cement raw material are uniformly mixed according to a certain mass ratio, and when the mass ratio of the porous material is 5%, the denitration rate reaches over 90% within the temperature range of 700-1000 ℃. The invention realizes the reutilization of industrial waste residue, changes waste into valuable and protects the environment; reducing agents such as ammonia water or urea are not used in the denitration process, so that the problems of potential safety hazard, secondary ammonia escape pollution and the like in the storage and transportation process of the reducing agents are solved; the prepared denitration material is directly sprayed into the cement kiln along with the cement raw materials, and the kiln does not need to be modified or extra equipment is not needed.

Description

Denitration material prepared from nickel slag and suitable for cement kiln and denitration method thereof

Technical Field

The invention relates to a method for removing nitrogen oxides by utilizing industrial waste residues in combination with a cement production process, in particular to a denitration material applicable to a cement kiln prepared by using nickel residues and a denitration method thereof, and belongs to the technical field of flue gas denitration treatment of industrial kilns.

Background

Nitrogen oxides (NOx), one of the atmospheric pollutants, present direct and potential hazards to human health, ecosystems, and building facilities. The main source of NOx is the combustion of fossil fuels, mainly including motor vehicle exhaust, nitrogen oxides from industrial production, etc. The discharge amount of nitrogen oxides in the cement kiln is second to that of tail gases of thermal power plants and motor vehicles, and becomes a third pollution source. At present, the more mature cement kiln denitration technology comprises a low-nitrogen combustion control technology, a Selective Catalytic Reduction (SCR) technology and a selective non-catalytic reduction (SCR) technologyCatalytic reduction technology (SNCR). The low-nitrogen combustion technology has low cost, but the denitration efficiency is low and generally does not exceed 30 percent, and the low-nitrogen combustion technology cannot reach the national emission standard. The SNCR denitration technique is to utilize NH₃Urea and the like as reducing agents and react with NOx at 800-1000 ℃ to generate N₂. The denitration efficiency is low, generally 30-50%, and the liquid ammonia consumption is large (the ammonia nitrogen ratio is about 1.6). SCR denitration technology refers to the utilization of a reducing agent (such as NH) under the action of a catalyst₃Urea) with NOx to N₂And H₂And O. The current SCR catalyst has high price, low performance stability and easy occurrence of catalyst poisoning, thus causing short service life of the catalyst. And the SCR and SNCR denitration technologies both need to use ammonia gas or urea as a reducing agent, need an ammonia (urea) storage device and an ammonia (urea) spraying device, have large occupied area, complicated reaction devices and high investment cost and operation cost, and can cause ammonia escape phenomenon to cause secondary pollution. Therefore, the method has important significance in selecting the denitration material which is low in cost, does not use reducing agents such as ammonia gas or urea and has high denitration rate.

The nickel slag is formed by FeO and SiO in the nickel smelting process₂Granulated slag, which is formed by water-quenching a melt as a main component, is one of the most discharged industrial waste residues. According to the nickel production process in China, about 6-16 t of nickel slag is discharged when 1t of nickel is produced. At present, the disposal mode of the nickel slag is stockpiling and idling, and because the nickel slag cannot be reasonably utilized for a long time, the stockpiled nickel slag in China reaches 4000 ten thousand tons, and about 200 thousand tons is newly added every year. The stockpiling and idling not only occupies land, causes serious pollution to the surrounding environment and great harm to human health, but also cannot recycle valuable components in the nickel slag. Therefore, the active component Fe is kept as much as possible during the nickel slag treatment, and impurity elements Ca, Mg and the like are removed, so that the nickel slag denitration catalyst has a good denitration effect, the cost is saved, and the resource utilization of the nickel slag is realized.

The invention aims to prepare a denitration material with high specific surface area by using nickel slag as a raw material, and combines a cement production process to directly spray the denitration material into a cement kiln, and the denitration material enters a preheater and a decomposing furnace along with the material, so as to achieve a method with higher denitration rate along with the rise of the temperature in the kiln when reducing agents such as ammonia gas or urea are not used.

Disclosure of Invention

Aiming at the problems, the invention develops an inorganic porous material suitable for cement kiln denitration by taking nickel slag as a raw material, and combines a cement production process to achieve a method with higher denitration rate without using reducing agents such as ammonia water or urea.

(1) The method for preparing the denitration material suitable for the cement kiln by taking the nickel slag as the raw material is characterized by comprising the following steps of:

preparing a porous denitration material by taking nickel slag as a raw material, mixing and stirring nickel slag powder and a diluted hydrochloric acid solution for 2 hours, and mixing the nickel slag powder and the hydrochloric acid solution in a mixing ratio of 10g in 60mL of diluted hydrochloric acid with the concentration of 3 mol/L; adding sodium hydroxide alkali solution to adjust the pH value to 3-11, and stirring for 30 min; centrifugally washing for more than three times, and drying the separated precipitate in a drying oven at 80 ℃ for 12 hours to obtain the porous denitration material.

Further, the concentration of the sodium hydroxide solution was 2 mol/L.

(2) At flue gas conditions of 1000ppm NO, N₂Is balance gas, the gas flow rate is 300ml/min, and the denitration is carried out under the temperature condition of 25-1000 ℃. The denitration method comprises the step of placing the prepared porous denitration material in a denitration testing device to test the denitration efficiency of the porous denitration material. With N₂The denitration rate of the porous material is high in a high-temperature region of 700-1000 ℃, and the denitration rate of the porous material is basically up to more than 80%, and can be up to 99.8%.

(3) Mixing a porous denitration material prepared by nickel slag and cement raw materials in different proportions, testing the denitration efficiency of the mixed sample at the high temperature of 700-1000 ℃, and when the mass ratio of the porous material is 1-5%, the denitration rate is still more than 80%. Wherein the denitration material accounts for 3-5% of the mixture by mass, and the denitration is higher in the temperature range of 700-1000 ℃.

The invention has the advantages that: firstly, one of the industrial waste residues, namely the nickel residue, is adopted as a raw material, a porous denitration material with a high specific surface area is obtained by using simple chemical treatment, and the industrial waste residues are recycled to really realize waste recycling. Secondly, reducing agents such as ammonia water or urea are not used, so that the problems of potential safety hazard and secondary pollution in the storage and transportation process of the reducing agents such as the ammonia water or the urea are solved; meanwhile, the cement raw materials and the prepared porous materials are mixed and sprayed into the cement kiln, no redundant device is required to be added, the existing kiln is not required to be modified, the operation is simple, and the cost is low. And the denitration efficiency of the porous denitration material prepared by nickel slag at the temperature of 25-1000 ℃ is determined, so that the denitration rate of the porous denitration material at the temperature of 700-1000 ℃ in a high-temperature area is high, basically reaches more than 80 percent and can reach 99.8 percent at most.

Drawings

FIG. 1 shows denitration rates of some examples 1, 2 and 3 of the present invention

Detailed Description

The present invention will be further illustrated with reference to the following examples, but the present invention is not limited to the following examples.

Example 1

Mixing 10g of nickel slag powder with 60ml of hydrochloric acid solution with the concentration of 3mol/L, stirring for 2 hours at room temperature, dropwise adding 2mol/L NaOH solution while continuously stirring, adjusting the pH value to 3, and stirring for 30 minutes; and (4) centrifugally separating out bottom sediment, washing for 3 times, and drying at 80 ℃ for 12 hours to obtain the denitration material powder. Simulated smoke composition 1000ppmNO, N₂The denitration efficiency is tested in the temperature range of 25-1000 ℃ as equilibrium gas with the gas flow rate of 300ml/min, the denitration rate is increased along with the temperature rise, the denitration rate is basically 85% at the high temperature of 700-1000 ℃ in a high-temperature area, the highest denitration rate is 98.3%, and the curve of the denitration rate along with the temperature change is shown in figure 1 (b).

Example 2

Mixing 10g of nickel slag powder with 60ml of hydrochloric acid solution with the concentration of 3mol/L, stirring for 2 hours at room temperature, dropwise adding 2mol/L NaOH solution while continuously stirring, adjusting the pH value to 7, and stirring for 30 minutes; centrifuging to separate out bottom precipitate, washing for 3 timesAnd drying at 80 ℃ for 12h to obtain the denitration material powder. Simulated smoke composition 1000ppmNO, N₂The denitration efficiency is tested in the temperature range of 25-1000 ℃ as equilibrium gas with the gas flow rate of 300ml/min, the denitration rate is higher at the high temperature of 700-1000 ℃ and is basically 95%, the highest denitration rate is 99.8%, and the curve of the denitration rate changing along with the temperature is shown in figure 1 (b).

Example 3

Mixing 10g of nickel slag powder with 60ml of hydrochloric acid solution with the concentration of 3mol/L, stirring for 2 hours at room temperature, dropwise adding 2mol/L NaOH solution while continuously stirring, adjusting the pH value to 11, and stirring for 30 minutes; and (4) centrifugally separating out bottom sediment, washing for 3 times, and drying at 80 ℃ for 12 hours to obtain the denitration material powder. Simulated smoke composition 1000ppmNO, N₂The denitration efficiency is tested in the temperature range of 25-1000 ℃ as equilibrium gas with the gas flow rate of 300ml/min, the denitration rate is 85% at the high temperature of 800-1000 ℃, the highest denitration rate is 99.4%, and the curve of the denitration rate changing with the temperature is shown in figure 1 (c).

Example 4

Preparation of denitration Material As described in example 2, the prepared denitration material was mixed with cement raw materials at a mixing ratio of 3% to 97% in a mass ratio, and after uniformly grinding the porous material and the cement raw materials with a mortar, 2mL of the mixed sample was charged into a denitration test tube. At flue gas conditions of 1000ppm NO, N₂The denitration rate of the porous material mixed with the cement raw material tested by the denitration device is basically more than 60 percent (shown in table 1).

Example 5

Preparation of denitration Material As described in example 2, the prepared denitration material was mixed with cement raw materials at a mixing ratio of 5% to 95% in a mass ratio to the cement raw materials, and after uniformly grinding the porous material and the cement raw materials with a mortar, 2mL of the mixed sample was charged into a denitration test tube. At flue gas conditions of 1000ppm NO, N₂Is balance gas, the gas flow rate is 300ml/min, the denitration temperature is 700-1000 ℃, the denitration rate of the porous material mixed with the cement raw material is still high by using a denitration device,it was maintained at 90% or more (see Table 1).

TABLE 1 Denitrification Rate/% of examples 4 and 5

	700℃	800℃	900℃	1000℃
					Example 4	64.83	81.02	92.45	96.63
Example 5	93.76	95.34	97.82	96.95

Claims

1. The method for preparing the denitration material suitable for the cement kiln by taking the nickel slag as the raw material is characterized by comprising the following steps of:

preparing a porous denitration material by taking nickel slag as a raw material, mixing and stirring nickel slag powder and a diluted hydrochloric acid solution for 2 hours, and mixing the nickel slag powder and the hydrochloric acid solution in a mixing ratio of 10g in 60mL of diluted hydrochloric acid with the concentration of 3 mol/L; adding sodium hydroxide alkali solution to adjust the pH value to 3-11, and stirring for 30 min; centrifugally washing for more than three times, and drying the separated precipitate in a drying oven at 80 ℃ for 12 hours to prepare a porous denitration material;

the concentration of the sodium hydroxide solution was 2 mol/L.

2. Use of the denitration material of claim 1, wherein the denitration material is produced under a flue gas condition of 1000ppm NO, N₂Is balance gas, the gas flow rate is 300ml/min, and the denitration is carried out under the temperature condition of 25-1000 ℃.

3. Use according to claim 2, wherein the flue gas conditions are 1000ppm NO, N₂The denitration material is used as balance gas, the gas flow rate is 300ml/min, the denitration material and the cement raw material are uniformly mixed according to different mass ratios, wherein the denitration material accounts for 3-5% of the mass ratio of the mixture, and the denitration is carried out within the temperature range of 700-1000 ℃.