CN110903104A

CN110903104A - Method for preparing foamed ceramic and co-producing calcium chloride and polyaluminium chloride by fluidized bed fly ash

Info

Publication number: CN110903104A
Application number: CN201811081381.5A
Authority: CN
Inventors: 张建波; 李少鹏; 李会泉; 胡文豪; 杨晨年
Original assignee: Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS
Priority date: 2018-09-17
Filing date: 2018-09-17
Publication date: 2020-03-24

Abstract

The invention provides a method for preparing foamed ceramic co-production calcium chloride and polyaluminium chloride by utilizing fluidized bed fly ash, which is developed through a large number of experiments, is a method for realizing the quality-divided utilization of calcium, aluminum and silicon by taking the fluidized bed fly ash as a raw material and carrying out graded regulation and control on diluted acid under mild conditions, and has the advantages of gradual progression, ring-to-ring buckling, optimized process flow, adjusted reaction parameters, synergistic synergy of all the steps, finally realizing the efficient utilization of the fluidized bed fly ash, greatly improving the added value of the product, and having wide application prospect and huge market value.

Description

Method for preparing foamed ceramic and co-producing calcium chloride and polyaluminium chloride by fluidized bed fly ash

Technical Field

The invention belongs to the field of chemistry, and designs a method for preparing foamed ceramic and co-producing calcium chloride and polyaluminium chloride by using fluidized bed fly ash.

Background

Coal is taken as the most important energy source in China, more than 60 percent of coal is burnt and converted by a pulverized coal furnace or a fluidized bed at present and is applied to the fields of thermal power generation and high-temperature steam production, but because the sulfur content is higher, tail gas purification is mainly realized by calcium spraying and desulfurization in the furnace at present, and sulfur components enter fly ash in the form of calcium sulfate to form high-calcium fly ash; due to the resource characteristics of high calcium of the fly ash, an effective resource utilization way is not formed at present, and the problems of serious pollution to atmosphere, soil, water and the like are caused mainly by stockpiling.

In view of the above problems, the resource utilization of fluidized bed fly ash has been paid much attention in recent years, and the present application mainly focuses on the fields of alumina extraction, composite material preparation and the like with respect to the elemental composition and the mineral phase structure characteristics of fluidized bed fly ash. In the aspect of alumina extraction, CN103820651A discloses a method for dissolving out aluminum from fly ash, which mainly uses a high-concentration hydrochloric acid alcohol solution as a reaction medium, and intensively leaches alumina under a high-temperature and high-pressure system, and recovers hydrochloric acid and alcohol through evaporation, thereby greatly reducing evaporation energy consumption. CN102153120A and CN104445212A disclose methods for extracting aluminum resource from fly ash in a circulating fluidized bed, respectively, which mainly mix fly ash with high-concentration hydrochloric acid solution, and intensively decompose inert aluminosilicate at high temperature and high pressure to realize high-efficiency extraction and separation of alumina. CN104556168A discloses a method for activating and dissolving out alumina in fly ash, which is mainly characterized in that the fly ash and ammonium bisulfate are mixed and then calcined and decomposed in a closed system, and then an aluminum sulfate solution is obtained after water-soluble separation, wherein the extraction rate of the alumina is as high as 85%. In the aspect of material preparation, CN106630715A discloses a method for preparing ceramsite by using circulating fluidized bed fly ash and paper sludge, and the ceramsite is mixed with industrial waste residue and paper sludgeMixing and granulating raw materials such as a plasticizer, a surfactant, feldspar and the like in proportion, and then sintering at a high temperature to obtain a ceramsite product; CN 107352887A discloses a preparation method of shrinkage-compensating foam concrete for a light composite partition board, which takes fluidized bed fly ash as a main raw material, adds auxiliary agents such as a foaming agent, a water reducing agent, a thickening agent and the like, and prepares a foam concrete material which is not easy to collapse, is not easy to fall off of a composite panel, is energy-saving and environment-friendly through the processes of burdening, forming, steam curing and the like; CN108147379A discloses a method for preparing sialon powder by utilizing acid-soluble slag of fly ash, which comprises the steps of grinding and mixing the sialon powder with carbon powder and Fe2O3, and regulating and controlling the C/Si ratio and Fe₂O₃The content is reacted under the high-temperature reducing atmosphere to obtain a sialon powder product. The process generally has the problems of harsh conditions of the dissolution process, high content of slag phase impurities, low product purity and performance parameters, waste of valuable resources and the like.

Therefore, a mild and efficient treatment method is developed, multiple components such as calcium, aluminum, silicon and the like are utilized according to different qualities, the method can be used as an important way for high-value utilization of resources, and the method has wide application prospect and great market value.

Disclosure of Invention

Aiming at the defects and practical requirements of the prior art, the invention provides a method for preparing foamed ceramic and co-producing calcium chloride and polyaluminium chloride by utilizing fluidized bed fly ash, the reaction condition is mild, the operation is simple, no secondary pollution is caused, the obtained foamed ceramic material has the advantages of low impurity content, high compressive strength, large aperture regulation and control operation elasticity and the like, the enterprise application requirements can be met, a new technology is provided for large-scale consumption and resource high-value conversion of the fluidized bed fly ash, and the obvious economic and environmental benefits are achieved.

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

in a first aspect, the invention provides a method for preparing foamed ceramic and co-producing calcium chloride and polyaluminium chloride by using fluidized bed fly ash, which comprises the following steps:

(1) mixing fluidized bed fly ash with water, adding hydrochloric acid to regulate pH, reacting, and separating to obtain decalcified fly ash and decalcified liquid;

(2) mixing the decalcified liquid with the fluidized bed fly ash, adding hydrochloric acid to regulate and control the pH value to react, separating after cyclic leaching decalcification to obtain a calcium-rich liquid and decalcified fly ash, and concentrating to obtain calcium chloride;

(3) mixing the decalcified fly ash obtained in the step (1) and the step (2) with hydrochloric acid, carrying out dealumination reaction, and separating to obtain dealumination acid liquid and dealumination slag coal ash;

(4) mixing the dealuminized acid solution and the decalcified fly ash, adding hydrochloric acid for reaction, promoting the dissolution of active aluminum, and performing multiple cycles to obtain aluminum-rich liquid and dealuminized slag;

(5) adding alkaline salt into the aluminum-rich liquid, carrying out polymerization reaction and curing reaction, separating to obtain a polyaluminium chloride product and decalcified fly ash, and continuing the dealumination reaction of the step (3) on the decalcified fly ash;

(6) and (4) mixing the dealuminized slag generated in the step (4) with a foaming agent, an adhesive and a stabilizer, forming, and sintering to obtain a foamed ceramic product.

In the invention, in the long-term production practice process, in order to realize the resource utilization of the fluidized bed fly ash, a method which takes the fluidized bed fly ash as a raw material and can realize the multi-component quality-divided utilization of calcium, aluminum and silicon by carrying out graded regulation and control on diluted acid under mild conditions is researched and developed through a large number of experiments aiming at the element composition and the mineral phase structure characteristic of the fluidized bed fly ash, the steps are gradually progressive and deducted, the process flow is optimized, the reaction parameters are adjusted, the conditions of the steps are synergistic, the efficient utilization of the fluidized bed fly ash is finally realized, the product added value is greatly improved, and the method has wide application prospect and great market value.

Preferably, the acid in steps (1) to (4) is selected from industrial by-product hydrochloric acid and/or industrial synthetic hydrochloric acid.

Preferably, the reaction temperature in step (1) is 25-95 deg.C, such as 25 deg.C, 35 deg.C, 45 deg.C, 55 deg.C, 60 deg.C, 65 deg.C, 75 deg.C, 85 deg.C or 95 deg.C.

Preferably, the liquid-solid ratio in step (1) is (3-5):1, and may be, for example, 3:1, 4:1 or 5: 1.

Preferably, the reaction time in step (1) is 30-180min, such as 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min or 180 min.

Preferably, the concentration of the hydrochloric acid in the step (1) is 200-430g/L, such as 200g/L, 220g/L, 240g/L, 260g/L, 280g/L, 300g/L, 320g/L, 340g/L, 360g/L, 380g/L, 400g/L or 430 g/L.

Preferably, the pH in step (1) is 3-4, and may be, for example, 3, 3.3, 3.5, 3.7, 3.9 or 4.

Preferably, the reaction temperature in step (2) is 25-95 deg.C, such as 25 deg.C, 35 deg.C, 45 deg.C, 55 deg.C, 60 deg.C, 65 deg.C, 75 deg.C, 85 deg.C or 95 deg.C.

Preferably, the liquid-solid ratio in step (2) is (3-5):1, and may be, for example, 3:1, 4:1 or 5: 1.

Preferably, the reaction time in step (2) is 30-180min, such as 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min or 180 min.

Preferably, the concentration of the hydrochloric acid in the step (2) is 200-430g/L, such as 200g/L, 220g/L, 240g/L, 260g/L, 280g/L, 300g/L, 320g/L, 340g/L, 360g/L, 380g/L, 400g/L or 430 g/L.

Preferably, the pH in step (2) is 3-4, and may be, for example, 3, 3.3, 3.5, 3.7, 3.9 or 4.

Preferably, the number of times of the cyclic leaching in the step (2) is 3 to 6, for example, 3, 4, 5 or 6 times.

Optionally, the step of cyclic leaching in step (2) is to mix the decalcified liquid with the fluidized bed fly ash, add hydrochloric acid to regulate pH, perform solid-liquid separation to obtain supernatant and precipitate, add new fluidized bed fly ash to the supernatant, and perform multiple cycles.

Preferably, the cyclic leaching process in the step (2) needs to be supplemented with hydrochloric acid.

Preferably, the concentration of the supplemented hydrochloric acid in the circulating leaching process in the step (2) is 300-430g/L, such as 300g/L, 320g/L, 340g/L, 360g/L, 380g/L, 400g/L or 430 g/L.

Preferably, the concentration method in step (2) is evaporative crystallization or spray drying.

Preferably, the temperature of the reaction in step (3) is 65-95 deg.C, and may be, for example, 65 deg.C, 70 deg.C, 75 deg.C, 80 deg.C, 85 deg.C, 90 deg.C or 95 deg.C.

Preferably, the reaction time in step (3) is 90-240min, such as 90min, 100min, 120min, 140min, 160min, 180min, 200min, 220min or 240 min.

Preferably, the liquid-solid ratio of the reaction in step (3) is (3-6):1, and may be, for example, 3:1, 4:1, 5:1 or 6: 1.

Preferably, the hydrochloric acid concentration of the reaction in the step (3) is 150-250g/L, such as 150g/L, 170g/L, 190g/L, 200g/L, 210g/L, 230g/L or 250 g/L.

Preferably, the number of cycles in step (4) is 3-6, and may be, for example, 3, 4, 5 or 6.

Preferably, the circulation in the step (4) is to mix the dealumination acid solution with the decalcified fly ash, supplement the hydrochloric acid solution into the dealumination acid solution, and perform circulation dealumination under the same acid leaching conditions as in the step (3).

In the invention, the acid leaching conditions refer to four conditions of temperature, liquid-solid ratio, reaction time and acid concentration, the concentration of the acid solution after reaction is reduced, and the purpose of adding hydrochloric acid is to improve the concentration of the circulating acid solution to be consistent with the initial reaction concentration.

Preferably, the reaction temperature in step (4) is 65-95 deg.C, such as 65 deg.C, 70 deg.C, 75 deg.C, 80 deg.C, 85 deg.C, 90 deg.C or 95 deg.C

Preferably, the reaction time in step (4) is 90-240min, such as 90min, 100min, 120min, 140min, 160min, 180min, 200min, 220min or 240 min.

Preferably, the liquid-solid ratio of the reaction in step (4) is (3-6: 1), and may be, for example, 3:1, 4:1, 5:1 or 6: 1.

Preferably, the concentration of the hydrochloric acid in the step (4) is 350-430g/L, such as 350g/L, 360g/L, 370g/L, 380g/L, 390g/L, 400g/L, 410g/L, 420g/L or 430 g/L.

Preferably, the alkaline salt in step (5) is fluidized bed fly ash.

Preferably, the liquid-solid ratio of the aluminum-rich liquid to the alkaline salt in the step (5) is 9-18mL/g, for example, 9mL/g, 10mL/g, 11mL/g, 12mL/g, 13mL/g, 14mL/g, 15mL/g, 16mL/g, 17mL/g or 18 mL/g.

Preferably, the number of additions of the basic salt in step (5) is 2 to 3, and may be, for example, 2 or 3.

Preferably, the basic salt is added in step (5) at intervals of 0.5-1h, for example 0.5h, 1h or 1.5 h.

Preferably, the polymerization reaction in step (5) is carried out at a temperature of 65 to 95 ℃ and may be, for example, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃ or 95 ℃.

Preferably, the polymerization reaction time in step (5) is 60-240min, such as 60min, 80min, 100min, 120min, 140min, 160min, 180min, 200min, 220min or 240 min.

Preferably, the polymerization reaction of step (5) has a pH of 3 to 5, which may be, for example, 3, 3.5, 4, 4.5 or 5.

Preferably, the temperature of the aging reaction in step (5) is 55-85 ℃, and may be, for example, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃ or 85 ℃.

Preferably, the time of the ripening reaction in step (5) is 12-48h, and may be 12h, 18h, 24h, 30h, 36h, 42h or 48h, for example.

Preferably, the weight part of the dealuminized slag in the step (6) is 50-85 parts, such as 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts or 85 parts; the foaming agent is 5-20 parts by weight, for example, 5 parts, 10 parts, 15 parts or 20 parts by weight, the adhesive is 5-10 parts by weight, for example, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts by weight, and the stabilizer is 5-10 parts by weight, for example, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts by weight.

Preferably, the foaming agent in step (6) comprises any one or a combination of at least two of carbon powder, starch, silicon carbide or carbonate.

Preferably, the binder in step (6) comprises any one or a combination of at least two of clay minerals, aluminum dihydrogen carbonate or water glass.

Preferably, the water content of the shaped product in step (6) is 0-5%, for example, 0%, 1%, 2%, 3%, 4% or 5%, preferably 3-4%.

Preferably, the pressure for the molding in step (6) is 100-.

Preferably, the sintering temperature in step (6) is 800-1400 ℃, and may be 800 ℃, 900 ℃, 1000 ℃, 1100 ℃, 1200 ℃, 1300 ℃ or 1400 ℃, for example.

Preferably, the sintering time in step (6) is 2-8h, such as 2h, 3h, 4h, 5h, 6h, 7h or 8 h.

Preferably, the temperature rise rate of the sintering in the step (6) is 1-5 ℃/min, for example, 1 ℃/min, 2 ℃/min, 3 ℃/min, 4 ℃/min or 5 ℃/min.

In brief, the method for preparing foamed ceramic and co-producing calcium chloride and polyaluminium chloride by using fluidized bed fly ash comprises the following steps:

(1) mixing fresh water and high-calcium fly ash, regulating the pH value of a system by adding a hydrochloric acid solution, selectively and efficiently dissolving out active calcium, and performing solid-liquid separation to obtain decalcified fly ash and a decalcifying liquid;

(2) mixing the decalcification solution with high-calcium fly ash, repeating the operation of the step (1), obtaining a calcium-rich solution after multiple cycles, and further obtaining a high-purity calcium chloride product by a spray drying or evaporative crystallization method;

(3) mixing the decalcified fly ash obtained in the steps (1) and (2) with a hydrochloric acid solution according to a liquid-solid ratio of 3:1-6:1, carrying out dealumination reaction, and then carrying out solid-liquid separation and washing to obtain dealumination acid liquid and dealumination slag coal ash;

(4) mixing the dealuminized acid solution with the decalcified fly ash, simultaneously adding fresh hydrochloric acid, and repeating the reaction process in the step (3) to perform circulating dealumination to obtain an aluminum-rich solution and dealuminized slag;

(5) adding high-calcium fly ash into the aluminum-rich solution to regulate and control the basicity and the polymerization degree, performing liquid-solid separation to obtain a liquid polyaluminium chloride product, and returning the solid to the step (3) to perform dealumination reaction;

(6) and (4) mixing, molding and sintering the dealuminized slag generated in the step (4) with a foaming agent, a bonding agent and a stabilizing agent to obtain a foamed ceramic product.

As a preferred technical scheme, the method for preparing foamed ceramic and co-producing calcium chloride and polyaluminium chloride by utilizing fluidized bed fly ash specifically comprises the following steps:

(1) mixing the fluidized bed fly ash and water according to the liquid-solid ratio of (3-5):1, adding hydrochloric acid with the concentration of 200-;

(2) mixing the decalcification solution with the fluidized bed fly ash according to the liquid-material ratio of (3-5):1, adding 200-430h/L hydrochloric acid to regulate the pH value to 3-4, reacting at the temperature of 25-95 ℃ for 30-180min, separating after circulating leaching and decalcification for 3-6 times to obtain a calcium-rich solution and decalcification fly ash, and evaporating and crystallizing or spray drying to obtain calcium chloride;

(3) mixing the decalcified fly ash obtained in the step (1) and the step (2) with hydrochloric acid with the concentration of 150-250g/L according to the liquid-solid ratio of (3-6) to 1, carrying out dealumination reaction at the reaction temperature of 65-95 ℃ for 90-240min, and separating to obtain dealumination acid liquid and dealumination slag coal ash;

(4) mixing the dealuminizing acid solution and the decalcified fly ash according to the liquid-solid ratio of (3-6):1, supplementing hydrochloric acid with the concentration of 350-;

(5) adding alkaline salt into the aluminum-rich liquid, wherein the liquid-solid ratio is 9-18mL/g, the adding times are 2-3 times, the adding time interval is 0.5-1h, carrying out polymerization reaction and curing reaction, the polymerization reaction temperature is 65-95 ℃, the polymerization reaction time is 60-240min, the polymerization reaction pH is 3-5, the curing reaction temperature is 55-85 ℃, the curing reaction time is 12-48h, separating to obtain a polyaluminium chloride product and decalcified fly ash, and continuously carrying out the dealuminization reaction in the step (3) on the decalcified fly ash;

(6) mixing 50-85 parts of the dealuminized slag generated in the step (4) with 5-20 parts of foaming agent, 5-10 parts of adhesive and 5-10 parts of stabilizer for molding, wherein the molded water content is 0-5%, the molding pressure is 100-200MPa, the foamed ceramic product is obtained by sintering, the sintering temperature is 800-1400 ℃, the sintering time is 2-8h, and the sintering temperature rise rate is 1-5 ℃/min.

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

the invention takes the fluidized bed fly ash as the raw material, can realize the quality-divided utilization of calcium, aluminum and silicon by the fractional regulation and control of dilute acid under mild conditions, greatly improves the added value of the product, and has the advantages of simple operation process, mild reaction conditions, large operation elasticity and the like, and has remarkable economic benefit; the calcium chloride and the polyaluminium chloride produced by the method have high purity and good performance, and compared with the traditional preparation method, the method only takes the fly ash as the raw material without consuming raw and auxiliary materials, thereby reducing the product cost, saving mineral resources and having remarkable social and environmental benefits.

Drawings

FIG. 1 is a flow chart of the present invention.

Detailed Description

To further illustrate the technical means and effects of the present invention, the following further describes the technical solutions of the present invention by way of specific embodiments with reference to the drawings, but the present invention is not limited to the scope of the embodiments.

Example 1

A method for preparing foamed ceramic material and co-producing polyaluminium chloride and calcium chloride by utilizing fluidized bed fly ash is disclosed, a flow chart is shown in figure 1, and the method comprises the following steps:

the preparation process of calcium chloride comprises the following steps: mixing fly ash and water according to a liquid-solid ratio of 4:1, adding hydrochloric acid with the concentration of 300g/L, adjusting the pH to 3.5, the reaction temperature to 45 ℃, the reaction time to 90min and the rotation speed to 350 r/min; after the reaction is finished, obtaining filtrate after solid-liquid separation and washing; mixing the filtrate and the fly ash raw material according to the proportion, performing circulating enrichment according to the conditions of the dilute acid decalcification process, circulating for 5 times, filtering to obtain a calcium-rich solution, adding calcium oxide into the calcium-rich filtrate, adjusting the pH of the system to be 6, adjusting the reaction temperature to be 55 ℃, reacting for 20min, and performing spray drying treatment to obtain a calcium chloride product.

The aluminum cycle leaching process: mixing the decalcified fly ash and industrial byproduct hydrochloric acid according to a liquid-solid ratio of 4:1, wherein the concentration of the hydrochloric acid is 300g/L, the reaction time is 120min, the reaction temperature is 85 ℃, and filtering is carried out after the reaction is finished to obtain an aluminiferous acid solution; adding industrial byproduct hydrochloric acid with the concentration of 400g/L into the aluminiferous acid solution to the required volume, carrying out cyclic leaching reaction according to the conditions, and obtaining an aluminiferous acid solution through solid-liquid separation after the cycle times reach 5 times;

polymerization regulation: adding fluidized bed high calcium fly ash raw ash serving as an alkaline regulator into the obtained aluminum-rich acid solution, controlling the pH to be 4, and performing polymerization regulation, wherein the liquid-solid ratio is 12mL/g, the polymerization temperature is 85 ℃, the polymerization time is 180min, the curing temperature is 65 ℃, and the curing time is 24h, so as to obtain a polyaluminium chloride product;

the process of burdening, forming and sintering comprises the following steps: 65 parts of dealuminized slag, 15 parts of carbon powder serving as a foaming agent, 8 parts of water glass serving as a binder and 8 parts of laterite serving as a stabilizer, mixing the raw materials, and forming under the pressure of 150 MPa; and further placing the ceramic material in a muffle furnace high-temperature device for sintering reaction, wherein the sintering temperature is 1200 ℃, the sintering time is 3h, and the heating rate is 3 ℃/min, so that the foamed ceramic product is obtained.

Example 2

A method for preparing a foamed ceramic material and co-producing polyaluminium chloride and calcium chloride by utilizing fluidized bed fly ash comprises the following steps:

the preparation process of calcium chloride comprises the following steps: mixing fly ash and fresh water according to a liquid-solid ratio of 3:1, adding hydrochloric acid with a concentration of 350g/L, adjusting the pH to 3, the reaction temperature to 55 ℃, the reaction time to 120min and the rotation speed to 350 r/min; after the reaction is finished, obtaining filtrate after solid-liquid separation and washing; mixing the filtrate and the fly ash raw material according to the proportion, circularly enriching according to the condition of the dilute acid decalcification process, circulating for 4 times, and filtering to obtain a calcium-rich solution; adding calcium oxide into the calcium-rich filtrate, adjusting the pH value of the system to 6, the reaction temperature to 45 ℃, reacting for 40min, and obtaining a calcium chloride product through evaporative crystallization treatment;

the aluminum cycle leaching process: mixing the decalcified fly ash and industrial byproduct hydrochloric acid according to a liquid-solid ratio of 3:1, wherein the concentration of the hydrochloric acid is 220g/L, the reaction time is 100min, the reaction temperature is 80 ℃, and filtering is carried out after the reaction is finished to obtain an aluminiferous acid solution; adding industrial byproduct hydrochloric acid with the concentration of 300g/L into the aluminiferous acid solution to the required volume, carrying out cyclic leaching reaction according to the conditions, and obtaining an aluminiferous acid solution through solid-liquid separation when the cycle times reach 6;

polymerization regulation: adding fluidized bed high calcium fly ash raw ash serving as an alkaline regulator into the obtained aluminum-rich acid liquor at an interval of 1h every time for 2 times, controlling the pH to be 3, and performing polymerization regulation, wherein the liquid-solid ratio is 9mL/g, the polymerization temperature is 95 ℃, the polymerization time is 240min, the curing temperature is 55 ℃, and the curing time is 48h to obtain a polyaluminium chloride product;

the process of burdening, forming and sintering comprises the following steps: the production method comprises the following steps of mixing 75 parts of dealuminized slag, 15 parts of silicon carbide serving as a foaming agent, 5 parts of starch serving as a binder and 5 parts of red soil serving as a stabilizer, and molding under the pressure of 180 MPa; and further placing the ceramic material in a muffle furnace high-temperature device for sintering reaction, wherein the sintering temperature is 1100 ℃, the sintering time is 4h, and the heating rate is 2 ℃/min, so that the foamed ceramic product is obtained.

Example 3

the preparation process of calcium chloride comprises the following steps: mixing fly ash and fresh water according to a liquid-solid ratio of 4:1, adding hydrochloric acid with a concentration of 400g/L, adjusting the pH to 4, reacting at 25 ℃, reacting for 180min and at a rotating speed of 350 r/min; after the reaction is finished, obtaining filtrate after solid-liquid separation and washing; mixing the filtrate and the fly ash raw material according to the proportion, circularly enriching according to the condition of the dilute acid decalcification process, circulating for 6 times, and filtering to obtain a calcium-rich solution; adding calcium oxide into the calcium-rich filtrate, adjusting the pH value of the system to 6, adjusting the reaction temperature to 65 ℃, and the reaction time to 60min, and obtaining a calcium chloride product through evaporative crystallization treatment;

the aluminum cycle leaching process: mixing the decalcified fly ash and industrial byproduct hydrochloric acid according to a liquid-solid ratio of 5:1, wherein the concentration of the hydrochloric acid is 250g/L, the reaction time is 210min, the reaction temperature is 65 ℃, and filtering is carried out after the reaction is finished to obtain an aluminiferous acid solution; adding industrial byproduct hydrochloric acid with the concentration of 400g/L into the aluminiferous acid solution to the required volume, carrying out cyclic leaching reaction according to the conditions, and obtaining an aluminiferous acid solution through solid-liquid separation after the cycle times reach 5 times;

polymerization regulation: adding fluidized bed high calcium fly ash raw ash serving as an alkaline regulator into the obtained aluminum-rich acid liquor at an interval of 1h every time for 2 times, controlling the pH to be 4, and performing polymerization regulation, wherein the liquid-solid ratio is 15mL/g, the polymerization temperature is 75 ℃, the polymerization time is 240min, the curing temperature is 45 ℃, and the curing time is 36h, so as to obtain a polyaluminium chloride product;

the process of burdening, forming and sintering comprises the following steps: 80 parts of dealuminized slag, about 10 parts of silicon carbide serving as a foaming agent, 5 parts of starch serving as a binding agent and 5 parts of red soil serving as a stabilizing agent are mixed and molded under the pressure of 200 MPa; and further placing the ceramic material in a muffle furnace high-temperature device for sintering reaction, wherein the sintering temperature is 1300 ℃, the sintering time is 6h, and the heating rate is 5 ℃/min, so that the foamed ceramic product is obtained.

Example 4

the preparation process of calcium chloride comprises the following steps: mixing fly ash and fresh water according to a liquid-solid ratio of 3:1, adding hydrochloric acid with the concentration of 300g/L, adjusting the pH to 3.5, the reaction temperature to 65 ℃, the reaction time to 30min and the rotation speed to 350 r/min; after the reaction is finished, obtaining filtrate after solid-liquid separation and washing; mixing the filtrate and the fly ash raw material according to the proportion, circularly enriching according to the condition of the dilute acid decalcification process, circulating for 5 times, and filtering to obtain a calcium-rich solution; adding calcium oxide into the calcium-rich filtrate, adjusting the pH value of the system to 6, the reaction temperature to 55 ℃, reacting for 45min, and performing spray drying treatment to obtain a calcium chloride product;

the aluminum cycle leaching process: mixing the decalcified fly ash and industrial byproduct hydrochloric acid according to a liquid-solid ratio of 5:1, wherein the concentration of the hydrochloric acid is 150g/L, the reaction time is 180min, the reaction temperature is 75 ℃, and after the reaction is finished, filtering to obtain an aluminiferous acid solution; adding 350g/L industrial byproduct hydrochloric acid into the aluminiferous acid solution to a required volume, carrying out cyclic leaching reaction according to the conditions, and carrying out solid-liquid separation to obtain an aluminiferous acid solution after the cycle times reach 6;

polymerization regulation: adding fluidized bed high calcium fly ash raw ash serving as an alkaline regulator into the obtained aluminum-rich acid liquor at an interval of 1h every time for 2 times, controlling the pH to be 3, and performing polymerization regulation, wherein the liquid-solid ratio is 18mL/g, the polymerization temperature is 75 ℃, the polymerization time is 210min, the curing temperature is 75 ℃, and the curing time is 24h, so as to obtain a polyaluminium chloride product;

the process of burdening, forming and sintering comprises the following steps: 70 parts of dealuminized slag, 10 parts of sodium carbonate serving as a foaming agent, 10 parts of aluminum dihydrogen phosphate serving as a binder and 10 parts of laterite serving as a stabilizer, mixing the raw materials, and forming under the pressure of 150 MPa; and further placing the mixture in a muffle furnace high-temperature device for sintering reaction, wherein the sintering temperature is 1000 ℃, the sintering time is 6h, and the heating rate is 4 ℃/min, so that the foamed ceramic product is obtained.

Example 5

the preparation process of calcium chloride comprises the following steps: mixing fly ash and fresh water according to a liquid-solid ratio of 3:1, adding hydrochloric acid with a concentration of 200g/L, adjusting the pH to 3.5, the reaction temperature to 95 ℃, the reaction time to 180min and the rotation speed to 350 r/min; after the reaction is finished, obtaining filtrate after solid-liquid separation and washing; mixing the filtrate and the fly ash raw material according to the proportion, circularly enriching according to the condition of the dilute acid decalcification process, circulating for 6 times, and filtering to obtain a calcium-rich solution; adding calcium oxide into the calcium-rich filtrate, adjusting the pH value of the system to 6, controlling the reaction temperature to 70 ℃ and the reaction time to 90min, and obtaining a calcium chloride product through evaporative crystallization treatment;

the aluminum cycle leaching process: mixing the decalcified fly ash and industrial byproduct hydrochloric acid according to a liquid-solid ratio of 3:1, wherein the concentration of the hydrochloric acid is 250g/L, the reaction time is 240min, the reaction temperature is 95 ℃, and filtering is carried out after the reaction is finished to obtain an aluminiferous acid solution; adding industrial byproduct hydrochloric acid with the concentration of 300g/L into the aluminiferous acid solution to the required volume, carrying out cyclic leaching reaction according to the conditions, and obtaining an aluminiferous acid solution through solid-liquid separation when the cycle times reach 6;

polymerization regulation: adding fluidized bed high calcium fly ash raw ash serving as an alkaline regulator into the obtained aluminum-rich acid liquor at an interval of 1h every time for 2 times, controlling the pH to be 3, and performing polymerization regulation, wherein the liquid-solid ratio is 18mL/g, the polymerization temperature is 95 ℃, the polymerization time is 240min, the curing temperature is 85 ℃, and the curing time is 48h to obtain a polyaluminium chloride product;

the process of burdening, forming and sintering comprises the following steps: the production method comprises the following steps of mixing 85 parts of dealuminized slag, 5 parts of carbon powder serving as a foaming agent, 5 parts of water glass serving as a binder and 5 parts of laterite serving as a stabilizer, and forming under the pressure of 200 MPa; and further placing the mixture in a muffle furnace high-temperature device for sintering reaction, wherein the sintering temperature is 1400 ℃, the sintering time is 8h, and the heating rate is 5 ℃/min, so that the foamed ceramic product is obtained.

Example 6

the preparation process of calcium chloride comprises the following steps: mixing fly ash and fresh water according to a liquid-solid ratio of 5:1, adding hydrochloric acid with a concentration of 430g/L, adjusting the pH to 4, reacting at 25 ℃, reacting for 30min and at a rotation speed of 350 r/min; after the reaction is finished, obtaining filtrate after solid-liquid separation and washing; mixing the filtrate and the fly ash raw material according to the proportion, circularly enriching according to the condition of the dilute acid decalcification process, circulating for 3 times, and filtering to obtain a calcium-rich solution; adding calcium oxide into the calcium-rich filtrate, adjusting the pH value of the system to 6, controlling the reaction temperature to be 30 ℃, controlling the reaction time to be 30min, and obtaining a calcium chloride product with the purity of more than 98 percent through evaporation and crystallization treatment;

the aluminum cycle leaching process: mixing the decalcified fly ash and industrial byproduct hydrochloric acid according to a liquid-solid ratio of 6:1, wherein the concentration of the hydrochloric acid is 150g/L, the reaction time is 90min, the reaction temperature is 65 ℃, and filtering is carried out after the reaction is finished to obtain an aluminiferous acid solution; adding an industrial byproduct hydrochloric acid with the concentration of 430g/L into the aluminiferous acid solution to a required volume, carrying out a circulating leaching reaction according to the conditions, and carrying out solid-liquid separation to obtain an aluminiferous acid solution after the circulating times reach 3 times;

polymerization regulation: adding fluidized bed high calcium fly ash raw ash serving as an alkaline regulator into the obtained aluminum-rich acid liquor at an interval of 0.5h every time for 3 times, controlling the pH to be 5, and performing polymerization regulation, wherein the liquid-solid ratio is 9mL/g, the polymerization temperature is 65 ℃, the polymerization time is 60min, the curing temperature is 55 ℃, and the curing time is 12h, so as to obtain a polyaluminium chloride product;

the process of burdening, forming and sintering comprises the following steps: 50 parts of dealuminized slag, about 20 parts of starch as a foaming agent, 10 parts of clay as a binder and 10 parts of red soil as a stabilizer, mixing the raw materials, and molding under the pressure of 100 MPa; further placing the mixture in a muffle furnace high-temperature device for sintering reaction, wherein the sintering temperature is 800 ℃, the sintering time is 2 hours, and the heating rate is 5 ℃/min, so as to obtain a foamed ceramic product;

example 7

The conditions were the same as in example 1 except that the pH was changed to 2 in the step of preparing calcium chloride, compared with example 1.

Example 8

The conditions were the same as in example 1 except that the pH in the step of preparing calcium chloride was changed to 6, as compared with example 1.

Example 9

Compared with the embodiment 1, the method has the same conditions as the embodiment 1 except that the concentration of the supplementary hydrochloric acid in the step of the aluminum circulating leaching is changed to be 100 g/L.

Example 10

The reaction was carried out under the same conditions as in example 1 except that the liquid-solid ratio in the polymerization reaction was changed to 6mL/g as compared with example 1.

Example 11

The reaction was carried out under the same conditions as in example 1 except that the liquid-solid ratio in the polymerization reaction was changed to 20mL/g as compared with example 1.

Comparative example 1

Compared with example 1, the conditions were the same as in example 1 except that the fluidized bed fly ash was changed to the pulverized coal furnace fly ash.

Comparative example 2

Compared with example 1, the conditions were the same as example 1 except that fluidized bed fly ash was used instead of decalcified fly ash in the step of aluminum recycle leaching.

Comparative example 3

The conditions were the same as in example 1 except that the number of cycles in the step of preparing calcium chloride was changed to 0, as compared with example 1.

Comparative example 4

The conditions were the same as in example 1 except that the number of cycles in the step of the aluminum cyclic leaching was changed to 0 as compared with example 1.

Experimental detection

Products in the process flows of the embodiment and the comparative example are detected by combining an inductively coupled plasma spectrometer with an X-ray fluorescence spectrometer, and the results are shown in table 1;

TABLE 1

As can be seen from Table 1, the calcium chloride, the aluminum chloride and the foamed ceramic prepared by the embodiments 1-6 according to the technical scheme provided by the invention have the advantages of excellent comprehensive performance, high content, purity and strength, and small impurity content; among these, the product obtained in example 5 has the best overall properties.

In the comparative example 1, the fluidized bed fly ash is not used as a raw material, so that the reaction is seriously mismatched with the whole reaction, and the product performance is comprehensively reduced;

comparative example 2 adopts fluidized bed fly ash to replace decalcified fly ash, so that the acid consumption is overlarge, the leaching rate of aluminum is reduced, and the synthesis and preparation of polyaluminium products are influenced;

compared with the method for preparing calcium chloride in the comparative example 3, the method of circular leaching is not adopted, multiple high-concentration solutions of calcium ions cannot be realized, the evaporation amount of water is greatly increased, and the energy consumption of subsequent evaporation or spray drying is increased;

comparative example 4 the dealumination does not adopt the step of circular leaching, the content of aluminum ions in the solution is low, the qualified polyaluminium product can not be prepared, and a large amount of original ore aluminum sources (bauxite, crystalline aluminum chloride and the like) need to be added, so that the raw material waste is caused;

in example 7, the pH is too low, a large amount of aluminum ions are separated out, and the impurity content of a calcium chloride product is high;

the pH value of the embodiment 8 is too high, calcium ions cannot be separated out efficiently, the yield of calcium chloride products is low, the acid consumption in the subsequent concentrated acid aluminum leaching process is increased, and the leaching rate of aluminum is reduced, so that the quality of polyaluminium products is reduced;

example 9 the concentration of the supplemented hydrochloric acid in the step of the aluminum cycle leaching is changed to 100g/L, the concentration of the hydrochloric acid is reduced, the high-efficiency dealumination cannot be performed, the aluminum ion precipitation effect is reduced, and the subsequent preparation of the polyaluminium product is influenced;

the liquid-solid ratio of example 10 and example 11 is beyond the range, which directly affects the reaction rate of the polymerization reaction and the curing reaction, and the basicity of the obtained polyaluminium chloride is beyond the range.

Therefore, the process flow of the invention is complete and efficient, the fluidized bed fly ash is comprehensively and comprehensively utilized, the product performance is excellent, the purity is high, the impurity content is low, the conditions of all the steps are matched with each other, the ring and the ring are buckled, the pH value, the material-liquid ratio, the reaction temperature, the reaction condition, the reaction sequence and the reaction raw materials supplement each other, the whole body is dragged, the mutual support and the synergistic synergy are realized instead of the isolated existence, and the high-efficiency production of the product is realized together.

In conclusion, the invention provides a method for preparing foamed ceramic and co-producing calcium chloride and polyaluminium chloride by utilizing fluidized bed fly ash, the reaction condition is mild, the operation is simple, no secondary pollution is caused, the obtained foamed ceramic material has the advantages of low impurity content, high compressive strength, large aperture regulation operation flexibility and the like, the enterprise application requirements can be met, a new technology is provided for large-scale digestion and resource high-value conversion of the fluidized bed fly ash, and obvious economic and environmental benefits are achieved.

The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. A method for preparing foamed ceramic and co-producing calcium chloride and polyaluminium chloride by utilizing fluidized bed fly ash is characterized by comprising the following steps:

(1) mixing fluidized bed fly ash with water, adding hydrochloric acid to regulate and control pH value for reaction, and separating after reaction to obtain decalcified fly ash and decalcifying liquid;

(4) mixing the dealuminized acid solution and the decalcified fly ash, supplementing hydrochloric acid for reaction, promoting the dissolution of active aluminum, and performing multiple cycles to obtain aluminum-rich liquid and dealuminized slag;

2. The method according to claim 1, wherein the temperature of the reaction of step (1) is 25-95 ℃;

preferably, the liquid-solid ratio in the step (1) is (3-5): 1;

preferably, the reaction time of the step (1) is 30-180 min;

preferably, the concentration of the hydrochloric acid in the step (1) is 200-430 g/L;

preferably, the pH in step (1) is 3 to 4.

3. The method according to claim 1 or 2, wherein the temperature of the reaction of step (2) is 25-95 ℃;

preferably, the liquid-solid ratio in the step (2) is (3-5): 1;

preferably, the reaction time of the step (2) is 30-180 min;

preferably, the concentration of the hydrochloric acid in the step (2) is 200-430 g/L;

preferably, the pH of step (2) is 3-4;

preferably, the number of the cyclic leaching in the step (2) is 3-6;

preferably, the cyclic leaching process in the step (2) needs to be supplemented with hydrochloric acid;

preferably, the concentration of the supplemented hydrochloric acid in the circulating leaching process in the step (2) is 300-430 g/L;

4. The process of any one of claims 1 to 3, wherein the temperature of the reaction of step (3) is 65 to 95 ℃;

preferably, the reaction time of the step (3) is 90-240 min;

preferably, the liquid-solid ratio of the reaction in the step (3) is (3-6): 1;

preferably, the hydrochloric acid concentration of the reaction in the step (3) is 150-250 g/L.

5. The method according to any one of claims 1 to 4, wherein the number of cycles of step (4) is 3 to 6;

preferably, the temperature of the reaction of step (4) is 65-95 ℃;

preferably, the reaction time of the step (4) is 90-240 min;

preferably, the liquid-solid ratio of the reaction in the step (4) is (3-6): 1;

preferably, the concentration of the hydrochloric acid in the step (4) is 350-430 g/L.

6. The method according to any one of claims 1 to 6, wherein the alkaline salt of step (5) is fluidized bed fly ash;

preferably, the liquid-solid ratio of the aluminum-rich liquid to the alkaline salt in the step (5) is 9-18 mL/g;

preferably, the number of the addition of the basic salt in the step (5) is 2 to 3;

preferably, the addition time interval of the alkaline salt in the step (5) is 0.5-1 h;

preferably, the temperature of the polymerization reaction in the step (5) is 65-95 ℃;

preferably, the time of the polymerization reaction in the step (5) is 60-240 min;

preferably, the polymerization reaction of step (5) has a pH of 3 to 5;

preferably, the temperature of the curing reaction in the step (5) is 55-85 ℃;

preferably, the time of the curing reaction in the step (5) is 12-48 h.

7. The method as claimed in any one of claims 1 to 6, wherein the weight part of the dealumination slag in the step (6) is 50 to 85 parts, the weight part of the foaming agent is 5 to 20 parts, the weight part of the binder is 5 to 10 parts, and the weight part of the stabilizer is 5 to 10 parts.

8. The method according to any one of claims 1-7, wherein the foaming agent of step (6) comprises any one or a combination of at least two of carbon powder, starch, silicon carbide or carbonate;

9. The method according to any one of claims 1 to 8, wherein the water content of the shaped product of step (6) is 0 to 5%, preferably 3 to 4%;

preferably, the pressure for the molding in the step (6) is 100-;

preferably, the sintering temperature in the step (6) is 800-1400 ℃;

preferably, the sintering time of the step (6) is 2-8 h;

preferably, the temperature rise rate of the sintering in the step (6) is 1-5 ℃/min.

10. Method according to any of claims 1-9, characterized in that it comprises the steps of:

(4) mixing the dealuminizing acid solution and the decalcified fly ash according to the liquid-solid ratio of (3-6):1, supplementing hydrochloric acid with the concentration of 350-430g/L to regulate and control the pH value for reaction, wherein the reaction temperature is 65-95 ℃, the reaction time is 90-240min, promoting the dissolution of active aluminum, and carrying out the dealuminizing reaction for 3-6 times by recycling leaching to obtain aluminum-rich liquid and dealuminizing slag;