CN104772214A

CN104772214A - Method for efficiently deironing coal ash

Info

Publication number: CN104772214A
Application number: CN201510174024.3A
Authority: CN
Inventors: 王明华; 李景钰; 刘泽昆; 刘宏阳
Original assignee: Northeastern University China
Current assignee: Northeastern University China
Priority date: 2015-04-14
Filing date: 2015-04-14
Publication date: 2015-07-15
Anticipated expiration: 2035-04-14
Also published as: CN104772214B

Abstract

The invention provides a method for efficiently deironing coal ash. Fine powder of raw coal ash is sequentially subjected to reduction, magnetic separation and hydrochloric acid leaching treatment, thereby finally obtaining the coal ash with the Fe2O3 content less than 0.02%. The method has the beneficial effects that the technology operation is simple, and the deironing efficiency is high, so that the Fe2O3 content in the coal ash is reduced to be lower than 0.02%; the calcium impurity also can be removed; moreover, a molecular sieve prepared by utilizing the coal ash after deironing by the method is high in quality, and the Fe2O3 content is less than the commercial value; not only can a duct of the molecular sieve be prevented from being blocked by a ferrum ion, but also the adsorption-desorption circulation service life can be prolonged. In addition, with the method, iron powder can be recycled in the magnetic separation process for iron smelting.

Description

A kind of method of fly ash highly deironing

Technical field

The present invention relates to the method for a kind of flyash reduction high-efficient deferrization.

Background technology

Flyash is the fine particle shape residue after coal or coal dust firing, is one of industrial residue that the current discharge capacity of China is larger.Nineteen ninety-five, China's flyash discharge capacity reached 1.25 hundred million tons, within 2000, be about 1.5 hundred million tons, within 2010, reach 300,000,000 tons, 5.7 hundred million tons will be reached according to scholarly forecast China's flyash discharge capacity in 2015, a large amount of flyash does not add process can produce airborne dust, atmosphere pollution, river can be caused to silt up, and toxic and harmful substance wherein also can work the mischief if enter water system to human body and biology.The comprehensive utilization of flyash is turned waste into wealth, and having become in China's economic construction an important techno-economic policy, is the important means solving contradiction between China's power generation environmental pollution and resource shortage.Current flyash is mainly as construction material, and for warming plate, slag cements, wall brick, floor etc., its use amount is large, and utilization rate reaches 67%, but added value of product is not high.The main component of flyash is silica and aluminium oxide, wherein silica content accounts for more than 70%, and silica and aluminium oxide are also the main components of molecular sieve, molecular sieve is expensive, is improve it to utilize the important channel of added value with cheap coal ash for manufacturing for molecular sieve.The application of molecular sieve widely; can be used for the dehydration of gas or liquid, drying, separation and purification; also can be used as adsorbent, catalyst and ion-exchanger for all kinds of reaction, play an important role in fields such as petrochemical industry, fine chemistry industry, agricultural, environmental protection.Utilize coal ash for manufacturing both can save raw material for molecular sieve, again can simple flow and equipment, for the large-scale production of molecular sieve and extensive use create conditions.

With the research of flyash synthesis of molecular sieve from 1985 by Holler and Wrisching; because environment in recent years protection work causes global extensive concern; increasingly burning hot to the research of flyash synthesis of molecular sieve both at home and abroad; the molecular sieve kind developed thus also gets more and more; but flyash is not pure aluminosilicate after all; except containing except valuable element sial also containing quite a few ferro element; make the molecular sieve for preparing mutually impure; not only easily block the duct of molecular sieve, and make the exchange capacity of molecular sieve and cycle performance on the low side.Therefore, with coal ash for manufacturing for molecular sieve before need to carry out pretreatment to flyash, removing iron wherein.

Document about deferrization of pulverized coal ash is more, mainly magnetic separation and pickling deironing.Invention CN10272561B and CN201848307U adopts the deironing of magnetic separation mode, but due to the mainly ferric iron of the iron in flyash, and ferric iron magnetic is faint, therefore effect is poor; Patent CN103131860A adds nitration mixture leaching deironing after adopting and adding alkali calcining and activating flyash, this mode is large to the consumption of soda acid, can not remove the whole iron in flyash; Northeast Petroleum University's Master's thesis of 2014---the research adopting two-step method to prepare ZSM-5 molecular sieve with powdered coal ash also reports and only relies on the mode of acidleach can not remove whole iron in flyash; Patent CN103833061A adopts combination method deironing to flyash dissolution fluid, and the method by the iron ion removing in solution, but can produce little effect to the iron in solid phase.

Summary of the invention

For the various problems that prior art exists, the invention provides a kind of method of fly ash highly deironing.Technical scheme of the present invention is:

A method for fly ash highly deironing, comprises following processing step:

(1) by the fine powder of raw meal coal ash and reducing agent nitrogen protection or with the condition of nitrogen under carry out reduction reaction, reaction temperature is 800 ~ 1100 DEG C, reaction time 20 ~ 60min, the consumption of reducing agent is 1.5 ~ 2 times of ferro element amount in flyash according to stoichiometric proportion;

(2) carry out 3 magnetic separation to the flyash of reduction, magnetic field intensity is 465-744kA m ^-1;

(3) by the flyash after magnetic separation with 10% hydrochloric acid solution be stir 4h under the condition of 60 ° of C to leach in temperature, obtain the flyash of deironing after filtration drying.

Fe in the fine powder of described raw meal coal ash ₂o ₃content be 4.42-7.84%, Task-size Controlling is at below 0.042mm.

The reducing agent of described reduction reaction is coal dust, coke blacking, carbon monoxide, coal gas or hydrogen.

Its Fe of the flyash of described deironing ₂o ₃content is lower than 0.02%.

Beneficial effect of the present invention: the method for a kind of fly ash highly deironing provided by the invention, technological operation is simple, and de-ironing efficiency is high, can make the Fe in flyash ₂o ₃content is down to less than 0.02%, and calcium impurities also can remove in the lump, and the molecular sieve quality utilizing the flyash after the method deironing to prepare is high, its Fe ₂o ₃content, lower than commercially available value, both can have been avoided iron ion to block the duct of molecular sieve, can improve again the cycle life of adsorption-desorption.In addition, this method can also reclaim in magnetic separation process and obtain iron powder, for making steel.

Accompanying drawing explanation

Fig. 1 is the standby molecular screen primary powder color contrast figure of coal ash for manufacturing that different method for removing iron obtains;

Fig. 2 is the process chart of the inventive method.

Detailed description of the invention

The flyash that the invention process adopts derives from Huaneng Group, Shanxi steam power plant.

The reducing agent (coal dust, coke blacking, coal gas or hydrogen) that the invention process adopts, hydrochloric acid are commercially available prod.

The invention process adopts CXG Φ 50 type magnetic separator to carry out magnetic separation.

Embodiment 1

Employing anchracite duff is reducing agent, and processing step is as follows:

(1) fine powder of raw meal coal ash and anchracite duff are carried out reduction reaction under with the condition of nitrogen, reaction temperature is 1000 DEG C, reaction time 40min, and the consumption of reducing agent is according to 1.5 times of stoichiometric proportion;

(2) carry out 3 magnetic separation to the flyash of reduction, magnetic field intensity is 465kAm ^-1;

(3) by the flyash after magnetic separation with 10% hydrochloric acid solution under the condition of temperature 60 ° of C, stir 4h leach, obtain Fe after filtration drying ₂o ₃content is the iron power removing coal ash of 0.019%.

Embodiment 2

Employing coke is reducing agent, and processing step is as follows:

(1) fine powder of raw meal coal ash and coke are carried out reduction reaction under with the condition of nitrogen, reaction temperature is 900 DEG C, reaction time 50min, and the consumption of reducing agent is according to 1.8 times of stoichiometric proportion;

(2) carry out 3 magnetic separation to the flyash of reduction, magnetic field intensity is 500kAm ^-1;

(3) by the flyash after magnetic separation with 10% hydrochloric acid solution under the condition of temperature 60 ° of C, stir 4h leach, obtain Fe after filtration drying ₂o ₃content is the iron power removing coal ash of 0.015%.

Embodiment 3

Employing hydrogen is reducing agent, and processing step is as follows:

(1) fine powder of raw meal coal ash and hydrogen are carried out reduction reaction under nitrogen protection, reaction temperature is 1100 DEG C, reaction time 20min, and the consumption of reducing agent is 2 times of the fine powder consumption of raw meal coal ash according to stoichiometric proportion;

(2) carry out 3 magnetic separation to the flyash of reduction, magnetic field intensity is 650 kAm ^-1;

(3) by the flyash after magnetic separation with 10% hydrochloric acid solution under the condition of temperature 60 ° of C, stir 4h leach, obtain Fe after filtration drying ₂o ₃content is the iron power removing coal ash of 0.013%.

Embodiment 4

Employing coal gas is reducing agent, and processing step is as follows:

(1) fine powder of raw meal coal ash and coal gas are carried out reduction reaction under nitrogen protection, reaction temperature is 800 DEG C, reaction time 60min, and the consumption of reducing agent is 1.9 times of the fine powder consumption of raw meal coal ash according to stoichiometric proportion;

(2) carry out 3 magnetic separation to the flyash of reduction, magnetic field intensity is 744 kAm ^-1;

(3) by the flyash after magnetic separation with 10% hydrochloric acid solution under the condition of temperature 60 ° of C, stir 4h leach, obtain Fe after filtration drying ₂o ₃content is the iron power removing coal ash of 0.017%.

The molecular sieve that table 1 is prepared through the flyash of the inventive method deironing compares with merely through the molecular sieve performance that magnetic separation-flyash of Leaching in Hydrochloric Acid deironing is prepared

Molecular sieve approach	Outward appearance	Fe ₂O ₃Content	The cycle life (secondary) of adsorption-desorption
				Prepared by the inventive method	White solid	<0.02%	5000
Magnetic separation-Leaching in Hydrochloric Acid preparation	Yellow solid	1.82～2.76%	200

Claims

1. a method for fly ash highly deironing, is characterized in that comprising following processing step:

2. the method for a kind of fly ash highly deironing according to claim 1, is characterized in that Fe in the fine powder of described raw meal coal ash ₂o ₃content be 4.42-7.84%, Task-size Controlling is at below 0.042mm.

3. the method for a kind of fly ash highly deironing according to claim 1, is characterized in that the reducing agent of described reduction reaction is coal dust, coke blacking, carbon monoxide, coal gas or hydrogen.

4. the method for a kind of fly ash highly deironing according to claim 1, is characterized in that its Fe of flyash of described deironing ₂o ₃content is lower than 0.02%.