CN100450968C

CN100450968C - Method for preparing microporous mullite aerated head(plate) by fly ash

Info

Publication number: CN100450968C
Application number: CNB2006100780206A
Authority: CN
Inventors: 赵子然; 迟振卿
Original assignee: INSTITUTE OF GEOLOGY CHINESE ACADEMY OF GEOLOGICAL SCIENCES
Current assignee: INSTITUTE OF GEOLOGY CHINESE ACADEMY OF GEOLOGICAL SCIENCES
Priority date: 2006-04-30
Filing date: 2006-04-30
Publication date: 2009-01-14
Anticipated expiration: 2026-04-30
Also published as: CN1844041A

Abstract

The present invention belongs to the technical field of special ceramics, which relates to a manufacturing method for a micropore aerating head/plate for filling oxygen into water effectively during the biochemical treatment process of sewage. The method can adopt the production technology of the traditional ceramic industry and directly use pulverized coal ash as a principal raw material to prepare micropore aerating head containing mullite. The micropore aerating head manufactured by the method is characterized in that the main crystal phase of the material is the mullite, the microcrystal is in a tetragonal cylinder shape and has the length of 4 to 12 mu m, and the main crystal phase and the microcrystal are staggered; the porosity of the material is from 35% to 50%, the pore diameters are distributed uniformly, and the pore space is between 2 mu m and 40 mu m and is mainly concentrated between 10 mu m and 20 mu m; the compressive strength is from 80 to 140MPa. The method has the advantages of simple manufacturing process, low cost, wide raw material sources, and high mechanical strength, good chemical stability and long service life of the micropore aerating head; in addition, the pore diameters of the micropore aerating head are distributed uniformly. Thereby, the present invention provides an economic and effective method with environmental protection, and also provides a new way for utilizing the pulverized coal ash resource effectively.

Description

The method of a kind of preparing microporous mullite aerated head (plate) by fly ash head (plate)

(1) technical field

The invention belongs to the special cermacis technical field, relate in the biochemical processing procedure of sewage manufacture method of the micro porous aeration head/plate of efficient oxygenation in water.

(2) background technology

Aeration is an important technological process in the sewage aerobic biological treatment system.The effect of micro-hole aerator is that air dispersion is become bubble, be diffused in the mixed solution, oxygen in the bubble is dissolved in the mixed solution, provide microbial biochemical reaction needed dissolved oxygen, guarantee the thorough mixing of sewage simultaneously, make active sludge be in suspended state,, guarantee that active sludge makes full use of oxygen in water and comes decomposing organic pollutant and nitrogen, phosphorus nutrition thing by mud, water, the triphasic abundant contact of gas.The quality of aeration effect greatly influences the efficient of biological treatment system, and the material of micro porous aeration head/plate and structure directly influence the aeration effect.

Micro porous aeration head all carried out development in states such as the U.S., Britain, France and Japan, and had product to sell.The micro porous aeration head of the U.S. and Japan's development, material is corundum matter and plastics matter.Units such as China Beijing municipal administration designing institute, Tianjin oilstone factory, the big tower refractory factory of Yixing City, the big new ceramics in Yixing factory also manufactured experimently aeration head/plate respectively, and material is respectively corundum matter and half corundum matter.

At present, the main material of micro porous aeration head has rubber diaphragm, polyethylene, corundum matter or half corundum matter.So far the relevant patent and the bibliographical information that also do not have microporous mullite aerated head.Elastomeric material, bad mechanical strength, corrosion is aging easily, and work-ing life is short; The polyethylene aeration head, though physical strength and chemical stability are better than rubber diaphragm, but as Treating Municipal Sewage or contain oils, phenols petrifaction sewage, particularly under use temperature in summer higher (reaching 46 ℃) and the higher condition of phenols concentration, weather resistance is generally not high, and its intensity also is difficult to adapt to the shearing stress of resisting current; Corundum matter or half corundum matter, the physical strength height, chemical stability is good, but gas distribution bed thickness, duct are coarse, easily stop up.Micro porous aeration head and manufacture method thereof (Chinese patent Granted publication number: CN1035053C) described method, provide that a kind of ultimate compression strength is good, air vent aperture is little, the micropore that is evenly distributed expose to the sun hole head and manufacture method thereof, but its firing time long (65 hours～75 hours), manufacturing process is numerous and diverse.The described method of half corundum matter micro porous aeration head and manufacture method thereof (Chinese patent Granted publication number: CN 1038443), component is too much, and the thing that forms material is complicated mutually, and adds too much quartz sand, influences the ultimate compression strength of material.

(3) summary of the invention

The present invention seeks to utilize flyash to be main raw material, prepare microporous mullite aerated head/plate, have the small characteristics such as evenly of high strength, anticorrosive, ageing-resistant, aperture, for the sewage biochemical treatment provide a kind of economy, effectively, the method for environmental protection.

The present invention realizes by such technical scheme, it is that flyash with special component is main raw material, powder raw materials such as same bauxitic clay, sintering agent according to component design, are prepared burden, wet ball grinding, drying, granulation, moulding, oven dry, roasting form.

Concrete steps are as follows:

1. flyash is handled: in 105 ℃ of fully oven dry, decide according to the flyash water content time of drying, below ball mill grinding to 200 order.

2. prepare burden: require to contain in the chemical composition of PCA higher Al ₂O ₃And SiO ₂, in the batching design, the composition of mullite provides aluminium and silicon by flyash, and the aluminium insufficient section is provided by bauxitic clay, and the weight percent of batching is:

Flyash 42～76%

Bauxitic clay 18～53%

Pore former (Wingdale or dolomite) 2～6%

Sintering agent (clay 30～50%, potassium felspar sand 50～70%) 2～5%

3. batch mixing, ball milling, drying: with the batch mixes wet ball grinding, to granularity meso-position radius 10 μ m, dry powder.

4. granulation, base, oven dry: the binding agent (polyvinyl alcohol or methylated cellulose aqueous solution) that adds weight percent 3～6% at powder at home and abroad, after the granulation, dry pressing in irony or steel mould, forming pressure is 40～60MPa, dries under 105 ℃ of conditions after suppressing the sample repaired biscuit.

5. fire: will dry base substrate and place industrial furnace or roasting in kilns, rise to 800 ℃ with 8 ℃/min temperature rise rate after, continue to heat up with the speed of 10 ℃/min, to firing temperature, be incubated 2～4 hours, firing temperature between 1300～1500 ℃, naturally cooling.

The gordian technique explanation:

The method of a kind of preparing microporous mullite aerated head (plate) by fly ash head/plate of the present invention, the flyash that adopts is aluminous fly-ash, mainly is made up of glass microballon and mullite crystallite, the microstructure of flyash is seen accompanying drawing 2.

The reaction mechanism of preparing microporous mullite aerated head (plate) by fly ash head:

The forming process of mullite crystallite: in when calcining, system forms part high-temperature liquid-phase amount, and original mullite crystallite absorbs on every side SiO in the glass melt in proportion in the flyash ₂And Al ₂O ₃, growth forms the mullite crystallite gradually; SiO in the fusion mutually ₂And Al ₂O ₃After reaching finite concentration, the beginning phase-splitting is in the impure point nucleation, particularly at high-melting-point Al ₂O ₃Separate out the mullite phase on every side, further growth forms the mullite crystallite.Potassium felspar sand plays fluxing action, forms more high-temperature liquid-phase amount, promotes the mullite microcrystalline growth.

The forming process of little pore: mainly be subjected to following four factor affecting.One discharges the pore that gas stays for pore former at high temperature decomposes; The two remaining pores that carry over for the base substrate particle packing: three are SiO ₂Due to the trans effect under capillary force action, because capillary action, liquid phase is Al towards periphery ₂O ₃Shift SiO in the gap ₂And Al ₂O ₃Constantly dissolving forms the mullite phase, after mullite is separated out mutually, and Si in the fusion mutually ⁴⁺And Al ³⁺Concentration constantly reduces, need be by SiO ₂And Al ₂O ₃Dissolving replenish SiO ₂Fusion and the transfer of liquid phase, cause at SiO ₂The particle place leaves over down hole; Four due to the volumetric expansion effect, form mullite crystal process volume and increase when generating mullite, make and suppressed remaining Al under capillary force action ₂O ₃Draw close mutually, and make SiO ₂The hole that the place stays is difficult to dwindle.

The inventive method can adopt the production technique of traditional ceramics industry, directly with flyash as main raw material, prepare microporous mullite aerated head, have the physical strength height, advantages such as even aperture distribution is fine, chemical stability good, long service life.Production technique of the present invention is simple, and is with low cost, and raw material sources are extensive, and also the high-efficiency resource recycling for flyash provides a kind of new way.China is the big country of flyash discharging, and the quantity discharged of flyash in 2002 reaches 1.8 hundred million tons, is open-air stacking mostly, and the accumulative total storage capacity surpasses 1,400,000,000 tons, occupies the arable land, contaminate environment.Current China utilization of fly ash level is also lower, mainly concentrates on aspects such as building materials body of wall, cement, concrete, roadbase.Though flyash becomes to be grouped into certain variation, its main chemical compositions is Al ₂O ₃And SiO ₂, main thing is glassy phase and mullite mutually, sees accompanying drawing 1.Mullite is Al ₂O ₃-SiO ₂The stable compound of system has many excellent characteristic, as thermostability, chemical stability and higher physical strength etc., is present important engineering structural ceramic material.The present invention utilizes the chemical ingredients of flyash and the advantage of thing phase composite, prepares microporous mullite aerated material, gives full play to its high strength, performance such as anticorrosive, ageing-resistant.

(4) description of drawings

Fig. 1 is the XRD figure of flyash of the present invention.

Fig. 2 is the SEM figure of flyash of the present invention.

Fig. 3 is the XRD figure of microporous mullite aerated head of the present invention.

Fig. 4 is microporous mullite aerated SEM figure of the present invention

(5) embodiment

To the north of the flyash of Beijing-to-Shijiazhuang Jingshan mountain power plant, raw materials such as same bauxitic clay, fusing assistant, according to component design, prepare burden, wet ball grinding, drying, granulation, moulding, dry, fire and goods.

Embodiment 1: batching add-on (weight percentage): 47.70 parts in flyash, 52.30 parts of bauxitic clays, 2.50 parts in Wingdale, 2.00 parts of potassium felspar sands, 1.00 parts of wilkinites; Firing temperature is 1450 ℃, soaking time 3 hours.

Embodiment 2: batching add-on (weight percentage): 58.33 parts in flyash, 41.67 parts of bauxitic clays, 2.50 parts in Wingdale, 2.00 parts of potassium felspar sands, 1.00 parts of wilkinites; Firing temperature is 1350 ℃, soaking time 3 hours.

Embodiment 3: batching add-on (weight percentage): 74.35 parts in flyash, 25.65 parts of bauxitic clays, 2.50 parts in Wingdale, 2.00 parts of potassium felspar sands, 1.00 parts of wilkinites; Firing temperature is 1350 ℃, soaking time 2 hours.

Embodiment result:

The present invention is utilized the preparing microporous mullite aerated head (plate) by fly ash head, carry out powder crystal X-ray diffraction (XRD), scanning electronic microscope (SEM) analysis, the result shows that the main crystalline phase of micro-pore aeration head material is a mullite, as Fig. 3; The mullite microcrystal is cubic column, length between 4～12 μ m, staggered arrangement, material porosity height, pore size distribution is more even, hole mainly concentrates between 10～20 μ m between 2～40 μ m.The The performance test results of microporous mullite aerated head sees Table 1.

The fundamental property of table 1 preparing microporous mullite aerated head (plate) by fly ash plate

Claims

1. the microporous mullite aerated head of a fly-ash Preparation, it is characterized in that: the weight percent of raw material dosage is:

Aluminous fly-ash 42-76%;

Bauxitic clay 18-53%;

Pore former 2-6%, the raw material of pore former consists of Wingdale or dolomite;

Sintering agent 2-5%, the raw material of sintering agent consists of clay and potassium felspar sand, its weight percent: clay 30-50%, potassium felspar sand 50-70%.

2. microporous mullite aerated head according to claim 1 is characterized in that: in the batching of the above raw material, add the binding agent that weight percent is 3-6% outward.

3. microporous mullite aerated head according to claim 2 is characterized in that: binding agent is polyvinyl alcohol or methylcellulose gum.

4. method by the preparing microporous mullite aerated head (plate) by fly ash head of claim 3; it is characterized in that: be main raw material with the aluminous fly-ash; with pore former, bauxitic clay and sintering agent mixing; wet ball grinding; the dry powder that gets; the interpolation binding agent mixes in powder, fires to form after tablets press granulation, pressure shape base, oven dry again.

5. the method for the microporous mullite aerated head of preparation according to claim 4 is characterized in that: the firing temperature of microporous mullite aerated head is 1300-1500 ℃, and soaking time is 2-4 hour.