CN111233356B

CN111233356B - Method and system for preparing sulphoaluminate cement from all solid waste of aluminum ash pretreatment

Info

Publication number: CN111233356B
Application number: CN202010161255.1A
Authority: CN
Inventors: 王文龙; 任常在; 成望海; 王旭江; 武双; 姚永刚; 刘全勋
Original assignee: Shandong Guxin Environmental Protection Technology Co ltd; Shandong Zhuolian Environmental Protection Technology Co ltd; Shandong University
Current assignee: Shandong Guxin Environmental Protection Technology Co ltd; Shandong Zhuolian Environmental Protection Technology Co ltd; Shandong University
Priority date: 2020-03-10
Filing date: 2020-03-10
Publication date: 2021-04-06
Anticipated expiration: 2040-03-10
Also published as: CN111233356A

Abstract

The invention discloses a method and a system for preparing sulphoaluminate cement by using all solid wastes of aluminum ash pretreatment, wherein the method comprises the following steps: heating aluminum ash to be not lower than 900 ℃ for heat treatment, homogenizing and mixing the heat-treated aluminum ash with red mud, desulfurized gypsum and carbide slag, drying the mixed material by utilizing hot gas generated by the heat treatment, then carrying out raw powder proportioning grinding on the dried material, and calcining the raw powder proportioning ground material to obtain sulphoaluminate cement clinker; the aluminum ash comprises secondary aluminum ash or the aluminum ash is secondary aluminum ash. The invention can ensure that the tail part of the rotary kiln is not easy to form a ring, avoid the blockage of a condenser, ensure the long-time operation and completely replace bauxite.

Description

Method and system for preparing sulphoaluminate cement from all solid waste of aluminum ash pretreatment

Technical Field

The invention relates to the fields of resource comprehensive utilization and environmental protection treatment of aluminum processing, building material technology and bulk industrial solid waste, and relates to a method and a system for preparing sulphoaluminate cement from all solid waste of aluminum ash pretreatment.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

The industrial solid waste is various waste residues, dust and other wastes discharged into the environment in the industrial production process, and can be divided into general industrial wastes (such as blast furnace slag, steel slag, red mud, tailings, fly ash, desulfurized fly ash, carbide slag, salt slurry and the like) and industrial harmful solid wastes. The annual output of industrial solid waste in China is basically maintained at about 30 hundred million tons, the utilization rate is basically maintained at 22% -25%, the same-ratio growth rate of the total industrial solid waste output is basically maintained unchanged from 2012, the same-ratio growth rate of the industrial solid waste utilization amount is gradually increased year by year, although the growth rate of the industrial solid waste utilization amount is gradually increased year by year, nearly 20 million tons of industrial solid waste are not disposed every year, wherein the individual industrial solid waste has complex components and great utilization difficulty, and the total new stock amount is 270 million tons.

The aluminum ash is one of industrial harmful solid wastes, is mainly generated in aluminum liquid discharged from an electrolytic cell and a casting link, and mainly comprises Al and Al₂O₃AlN and a certain amount of fluoride and chloride, and ammonia gas can be generated in the presence of water or in a humid environment, so that the ecological safety of the periphery of a storage yard is influenced. In the primary aluminum industrial production, 30-50 kg of aluminum ash is generated for each 1 ton of aluminum, in the secondary aluminum industrial production process, 30-40 kg of aluminum ash is generated for each ton of aluminum, and 20-25 ten thousand tons of aluminum slag is generated in the consumption link every year, so that the total amount of the aluminum ash generated in each link of aluminum production, aluminum processing, aluminum consumption and the like every year is more than 300 ten thousand tons, and the aluminum ash accumulated in the early aluminum industrial development process is added, and the total amount of the aluminum ash is at least more than 2000 ten thousand tons. In the existing aluminum ash recovery and utilization methods, the recovery and heat treatment methods of aluminum in secondary aluminum ash basically have the contradiction between the recovery efficiency and high energy consumption, while the cold treatment method has low energy consumption, but the aluminum recovery rate is low, and the secondary pollution is large.

In recent years, sulphoaluminate cement becomes a new direction for research and development of the cement industry at home and abroad, and cement clinker has a series of excellent performances of low heat consumption, high early strength, short setting time, excellent freeze-thaw resistance, low alkalinity and the like required by production, and is widely applied to rush repair, rush construction engineering, winter construction engineering and corrosion resistance engineering. The basic raw materials used for producing sulphoaluminate cement in the prior art are limestone, bauxite and gypsum, the limestone serving as a calcium raw material mainly provides a calcium oxide component required in the forming process of sulphoaluminate cement clinker, and the bauxite serving as an aluminum raw material mainly provides an aluminum oxide component required in the forming process of the sulphoaluminate cement clinker; the gypsum is used as a sulfur raw material to mainly provide sulfur trioxide components required in the forming process of the sulphoaluminate cement clinker. According to the knowledge of the inventor of the present invention, the aluminum ash has been studied as the alumina raw material in the preparation process of the sulphoaluminate cement, however, the studies are limited to laboratory studies and pilot-scale tests, and are not widely applied in the actual production. In actual production, some production enterprises add a certain amount of aluminum ash to the raw materials to replace bauxite, so that the raw material cost is reduced. However, in practical application of the present invention, it is found that when the bauxite is partially replaced by the aluminum ash, the rotary kiln tail is easy to form a ring, the condenser is blocked, the operation is difficult for a long time, and the bauxite cannot be completely replaced by the aluminum ash.

Disclosure of Invention

In order to solve the defects of the prior art, the invention aims to provide a method and a system for preparing sulphoaluminate cement by using all solid wastes of aluminum ash pretreatment, which can ensure that the tail part of a rotary kiln is not easy to form a ring, avoid the blockage of a condenser, ensure long-time operation and completely replace bauxite.

In order to achieve the purpose, the technical scheme of the invention is as follows:

on one hand, the method for preparing the sulphoaluminate cement by using the aluminum ash comprises the steps of heating the aluminum ash to be not lower than 900 ℃ for heat treatment, and preparing the sulphoaluminate cement by using the heat-treated aluminum ash as an aluminum source; the aluminum ash comprises secondary aluminum ash or the aluminum ash is secondary aluminum ash.

In practice it has been found that when the bauxite is partially replaced directly with the fly ash, the fly ash can replace up to 30% of the bauxite, and when the fly ash replaces 30% of the bauxite, it makes it easier for the tail of the rotary kiln to ring and block the condenser. The research of the inventor of the invention finds that the process for preparing aluminum in an aluminum plant is generally an electrolytic method, so that sodium chloride, potassium chloride and other salts exist in aluminum ash generated in the aluminum plant, and when cement is prepared in a rotary kiln, the sodium chloride, potassium chloride and other salts are easily brought out by steam, carbon dioxide and other gases in the calcining process, so that the salts are deposited at the tail part of the rotary kiln, and the tail part of the rotary kiln is more easily formed. Therefore, the present inventors have made initial studies mainly to remove salts such as sodium chloride and potassium chloride from the aluminum ash, and since sodium chloride and potassium chloride are readily soluble in water, a solution method (for example, homogenization in water) is preferred.

After the homogenization is carried out only by using water, the salts such as sodium chloride, potassium chloride and the like can be completely removed, and the amount of the aluminum ash replacing bauxite can be increased, however, the phenomena of ring formation and condenser blockage are still easy to occur along with the increase of the amount of the aluminum ash after the homogenization by using water, and obvious pungent odor is generated along with the increase of the amount of the aluminum ash, so that the sulphoaluminate cement cannot be normally produced. Further research shows that the aluminum ash also contains simple aluminum substances, the melting point of the simple aluminum substances is low, and the simple aluminum substances are melted in the rotary kiln and then form large blocks, so that the discharging at the outlet of the kiln is difficult. Through the analysis to pungent smell gas, this gas is mainly the ammonia, further study to the aluminium ash finds that the aluminium ash divide into first aluminium ash and secondary aluminium ash, and the aluminium factory generally can utilize first aluminium ash, leads to the content of secondary aluminium ash in its aluminium ash that produces to be higher, has aluminium nitride (AlN) more in the secondary aluminium ash, when adopting water to carry out homogenization treatment, produces the ammonia easily, and the increase of aluminium ash volume leads to the volume of aluminium nitride to increase to improve the production of ammonia.

Therefore, in order to remove the aluminum simple substance and the aluminum nitride, the corresponding influence is generally removed by adding a chemical reagent to perform corresponding treatment, thereby solving the corresponding problem. However, through further research, it is found that high-salinity wastewater is generated after adding a chemical reagent, the high-salinity wastewater is difficult to treat, and the cost of an enterprise is increased due to greatly increased processes.

According to the invention, the aluminum ash containing the secondary aluminum ash is treated at the temperature of not less than 900 ℃, and researches show that when the treatment temperature is 700 ℃, the aluminum nitride undergoes denitrification reaction and gradually becomes aluminum oxide; when the temperature is above 900 ℃, the aluminum nitride can be basically converted into aluminum oxide, salts such as sodium chloride and potassium chloride are gasified, and the simple substance of aluminum can be processed into aluminum oxide. Aluminum ash including secondary aluminum ash subjected to heat treatment at not less than 900 deg.C, substantially with Al₂O₃And MgAl₂O₄Minerals exist, and therefore, the bauxite is completely replaced. Actual operation shows that the aluminum ash and aluminum source after heat treatment completely replaces bauxite to prepare the sulphoaluminate cement, and the phenomena of tail ring formation and condenser blockage in the production process of the rotary kiln are avoided.

Because the current industrial solid wastes (such as red mud, desulfurized gypsum, carbide slag and the like) have the problem of difficult treatment, and simultaneously a large amount of energy is consumed for heat treatment of the aluminum ash, in order to recycle the industrial solid wastes and reduce the energy consumption, the invention also discloses a method for preparing sulphoaluminate cement by using the whole solid wastes of the aluminum ash pretreatment, which comprises the steps of heating the aluminum ash to be not lower than 900 ℃ for heat treatment, homogenizing and mixing the aluminum ash after the heat treatment with the red mud, the desulfurized gypsum and the carbide slag, drying the mixed materials by using hot gas generated by the heat treatment, then carrying out raw powder proportioning grinding on the dried materials, and calcining the raw powder proportioned and ground materials to obtain sulphoaluminate cement clinker; the aluminum ash comprises secondary aluminum ash or the aluminum ash is secondary aluminum ash.

According to the invention, a large amount of waste heat is generated in the process of heat treatment of the aluminum ash, for example, the aluminum ash after heat treatment contains a large amount of waste heat, hot gas (flue gas heat and waste gas heat generated by calcining the aluminum ash) is generated after heat treatment, and the red mud, the desulfurized gypsum and the carbide slag contain more water, so that the red mud, the desulfurized gypsum and the carbide slag are dried by using the waste heat generated in the process of heat treatment of the aluminum ash, the energy utilization rate is increased, the energy consumption is reduced, the treatment of industrial solid waste can be realized, and the waste with the lowest economic value is converted into the sulphoaluminate cement with higher economic value.

In order to realize the preparation of the sulphoaluminate cement from the whole solid waste of the aluminum ash pretreatment, the third aspect of the invention is a system for realizing the preparation of the sulphoaluminate cement from the whole solid waste of the aluminum ash pretreatment, which comprises an indirect rotary drum heating furnace, a cyclone condenser, a dryer, a raw material pulverizer and a rotary kiln, wherein an inlet of the indirect rotary drum heating furnace is arranged to be connected with an aluminum ash source, a solid phase outlet of the indirect rotary drum heating furnace is connected with a material inlet of the dryer, a gas phase outlet of the indirect rotary drum heating furnace is connected with an inlet of the cyclone condenser, a gas phase outlet of the cyclone condenser is connected with a heat exchange gas inlet of the dryer, a material inlet of the dryer is also arranged to be connected with a red mud source, a desulfurized gypsum source and an acetylene sludge source, a material outlet of the dryer is connected with an inlet of the raw material pulverizer, and.

The invention adopts an indirect rotary drum heating furnace to indirectly heat the aluminum ash. Compare with direct heating, indirect heating can prevent that the flue gas that produces after the fuel burning from taking the aluminium ash out, if the aluminium ash is taken out by the flue gas, then can lead to the aluminium ash to be difficult to with the smoke and dust separation in the flue gas to be difficult to recycle the aluminium ash. Meanwhile, the gas gasified by sodium and potassium salts can be extracted by indirect heat exchange and enters a condenser for condensation and collection.

The invention has the beneficial effects that:

1. according to the invention, the aluminum ash is subjected to heat treatment, so that the impurities such as aluminum nitride, sodium chloride and potassium chloride in the aluminum ash can be greatly reduced, and the sulphoaluminate cement prepared from the aluminum ash after heat treatment can ensure that the tail part of the rotary kiln is not easy to form a ring and avoid the blockage of a condenser. Greatly improves the added value of the regenerated products of bulk industrial solid wastes such as aluminum ash, red mud and the like, and obviously reduces the control difficulty of the process.

2. The invention can greatly improve the utilization rate of the aluminum ash in the preparation of the sulphoaluminate cement by carrying out heat treatment on the aluminum ash, and reduces the cost and energy consumption of secondary aluminum ash treatment.

3. The waste heat after heat treatment is mixed with the red mud, the desulfurized gypsum and the carbide slag for heat exchange, and the waste heat enters the raw material system again, so that the energy is saved, and the environment is protected.

4. The invention can fundamentally and greatly reduce, stabilize, make harmless and recycle dangerous industrial solid wastes and general industrial solid wastes simultaneously.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a schematic structural diagram of a system according to embodiment 1 of the present invention;

FIG. 2 is an XRD pattern of the aluminum ash used in example 1 of the present invention before calcination;

FIG. 3 is an XRD pattern of calcined aluminum ash used in example 1 of the present invention;

the system comprises a hopper 1, an automatic weighing scale 2, an indirect rotary drum heating furnace 3, natural gas 4, a burner nozzle 5, a red mud storage bin 6, a desulfurized gypsum storage bin 7, a carbide slag storage bin 8, a belt conveyor 9, a discharging pipeline 10, an air extractor 11, a cyclone condenser 12, a cooling fan 13, a salt storage bin 14, a rotary drying cylinder 15, a raw material pulverizer 16, a dry raw material bin 17, a rotary kiln 18 and a material pulverizer 19.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

In view of the problems that bauxite is difficult to completely replace by aluminum ash in actual production and the tail of the rotary kiln is easy to form a ring, a condenser is blocked and the like when partial bauxite is replaced by the aluminum ash, the invention provides a method and a system for preparing sulphoaluminate cement by using all solid wastes of aluminum ash pretreatment.

In a typical embodiment of the present invention, a method for preparing sulphoaluminate cement by using aluminum ash is provided, wherein the aluminum ash is heated to not less than 900 ℃ for heat treatment, and the aluminium ash after the heat treatment is used as an aluminium source to prepare sulphoaluminate cement; the aluminum ash comprises secondary aluminum ash or the aluminum ash is secondary aluminum ash.

The method aims to treat aluminum ash into an aluminum source capable of replacing bauxite in the actual production of sulphoaluminate cement, and the aluminum source after heat treatment can replace the aluminum source in sulphoaluminate cement in any prior art; for example:

1. in the existing production, limestone, bauxite and gypsum are adopted to prepare sulphoaluminate cement (production and application of sulphoaluminate cement, Beijing of Zhang Qiu English, Singzagong Jun 2006 of Chinese building materials industry);

2. the existing preparation of sulphoaluminate cement by using aluminium-containing ash (CN201810935060.0, CN201710159992.6, CN201710159979.0 and the like);

alternatively, the preparation of other prior art sulphoaluminate cements is described.

In one or more embodiments of this embodiment, the heat treatment temperature is 900 to 950 ℃.

In one or more embodiments of this embodiment, the heat treating the aluminum ash is by indirect heating.

In order to effectively utilize the energy consumed by the heat treatment of the aluminum ash and simultaneously carry out the synergistic treatment of the industrial solid waste, the other embodiment of the invention provides a method for preparing sulphoaluminate cement from the whole solid waste of the aluminum ash pretreatment, the aluminum ash is heated to be not lower than 900 ℃ for heat treatment, the heat-treated aluminum ash, the red mud, the desulfurized gypsum and the carbide slag are homogenized and mixed, the mixed material is dried by using hot gas generated by the heat treatment, the dried material is ground in a raw powder proportioning manner, and the ground material in the raw powder proportioning manner is calcined to obtain sulphoaluminate cement clinker; the aluminum ash comprises secondary aluminum ash or the aluminum ash is secondary aluminum ash.

The desulfurized gypsum is a byproduct gypsum after desulfurization in a power plant.

The red mud in the invention is waste red mud discharged from an alumina plant.

The carbide slag in the invention is the waste slag which takes calcium hydroxide as a main component after acetylene gas is obtained by hydrolyzing carbide.

The raw powder proportioning grinding in the invention is to add dry materials in proportion, mix, grind and homogenize.

In one or more embodiments of this embodiment, the heat treatment temperature is 900 to 950 ℃. The raw aluminum ash contains a large amount of Al, AlN and Al₂O₃And after the minerals such as NaCl and the like are subjected to high-temperature denitrification and desalination reaction at 900-950 ℃, the AlN, NaCl and Al minerals in the aluminum ash basically disappear and Al is basically used₂O₃And MgAl₂O₄The processed aluminum ash can be used as high-grade bauxite due to the existence of minerals, so that a large amount of natural use is reduced, and the cost of raw materials is reduced in a larger range.

In one or more embodiments of the present disclosure, the mass ratio of the red mud, the desulfurized gypsum, the carbide slag, and the aluminum ash is 15-25: 20-30: 30-40: 15-25. The correction operation after the dry grinding can be reduced.

In one or more embodiments of this embodiment, the moisture of the dried material is less than 5 mass%.

In one or more embodiments of this embodiment, the particle size of the raw meal is less than 8 μm after being milled.

In one or more embodiments of this embodiment, the raw meal is proportioned to the ground ingredient, SiO ₂ 10～25wt％，CaO 20～30wt％，Al₂O₃ 20～30wt％，Fe₂O₃ 5～15wt％，SO₃ 20～30wt％。

In this series of examples, the basicity coefficient C_m0.90 to 1.05.

Wherein, the formula of the alkalinity coefficient is as follows:

in the formula, CaO and SiO₂、Al₂O₃、Fe₂O₃、TiO₂、SO₃Respectively the weight percentage of the corresponding chemical components.

In one or more embodiments of this embodiment, the temperature of the calcination is 1230 to 1260 ℃. The calcination time is 30-50 min.

In the series of embodiments, the flue gas generated by the heat treatment directly dries the material, and the waste gas generated by the heat treatment of the aluminum ash is subjected to cyclone separation and then dries the material.

In one or more embodiments of the embodiment, natural gas is adopted to calcine materials in the rotary kiln through the burner, and the excess air coefficient is controlled to be 1.1-1.15.

In one or more embodiments of this embodiment, the sulphoaluminate cement clinker is mixed with desulphurised gypsum and ground to obtain sulphoaluminate cement.

In order to realize the preparation of the sulphoaluminate cement from the whole solid waste of the aluminum ash pretreatment, the third embodiment of the invention provides a system for realizing the preparation of the sulphoaluminate cement from the whole solid waste of the aluminum ash pretreatment, which comprises an indirect rotary drum heating furnace, a cyclone condenser, a dryer, a raw material pulverizer and a rotary kiln, wherein an inlet of the indirect rotary drum heating furnace is arranged to be connected with an aluminum ash source, a solid phase outlet of the indirect rotary drum heating furnace is connected with a material inlet of the dryer, a gas phase outlet of the indirect rotary drum heating furnace is connected with an inlet of the cyclone condenser, a gas phase outlet of the cyclone condenser is connected with a heat exchange gas inlet of the dryer, a material inlet of the dryer is also arranged to be connected with a red mud source, a desulfurized gypsum source and an acetylene sludge source, a material outlet of the dryer is connected with an inlet of the raw material pulverizer, and an outlet of the.

The invention adopts an indirect rotary drum heating furnace to indirectly heat the aluminum ash. Compare with direct heating, indirect heating can prevent that the flue gas that produces after the fuel burning from taking the aluminium ash out, if the aluminium ash is taken out by the flue gas, then can lead to the aluminium ash to be difficult to with the smoke and dust separation in the flue gas to be difficult to recycle the aluminium ash.

In one or more embodiments of this embodiment, the salt storage bin is included, and the solid phase outlet of the cyclone condenser is connected with the salt storage bin.

One or more embodiments of this embodiment include a material pulverizer, the outlet of the rotary kiln being connected to the material pulverizer.

In one or more embodiments of this embodiment, the rotary kiln comprises a dust remover, and the flue gas outlet of the rotary kiln is connected with the dust remover.

In one or more embodiments of this embodiment, the dryer is a rotary dryer. The heat exchange of the red mud, the desulfurized gypsum and the carbide slag can be directly carried out by utilizing the waste heat of the air after the heat treatment, so that the energy utilization rate is improved.

In the indirect rotary drum heating furnace, the burner is arranged outside the wall of the rotary drum, heats the wall of the rotary drum, and heats materials in the rotary drum through heat transfer of the wall of the rotary drum, such as a rotary roasting furnace and the like.

In order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.

Example 1

A system for preparing sulphoaluminate cement from all solid wastes of aluminum ash pretreatment is shown in figure 1, and comprises a hopper 1, an automatic weighing scale 2, an indirect rotary drum heating furnace 3, a burner nozzle 5, a red mud storage bin 6, a desulfurized gypsum storage bin 7, a carbide slag storage bin 8, a belt conveyor 9, a blanking pipeline 10, an air extractor 11, a cyclone condenser 12, a cooling fan 13, a salt storage bin 14, a rotary drying drum 15, a raw material pulverizer 16, a dry raw material bin 17, a rotary kiln 18 and a material pulverizer 19.

Aluminum ash is firstly fed into an automatic weighing scale 2 through a hopper 1 and is sent into an indirect rotary drum heating furnace 3 through a belt conveyor, natural gas 4 heats the indirect rotary drum heating furnace 3 through a burner nozzle 5 to realize high-temperature calcination denitrification and desalination of the aluminum ash in the indirect rotary drum heating furnace 3, the aluminum ash after high-temperature calcination denitrification and desalination directly enters a rotary drying cylinder 15 through a feeding pipeline 10, raw materials in a red mud bin 6, a desulfurized gypsum bin 7 and an acetylene sludge bin 8 are conveyed into the rotary drying cylinder 15 through a belt conveyor 9, and the aluminum ash, the red mud, the desulfurized gypsum and the acetylene sludge after heat treatment in the rotary drying cylinder 15 are premixed and prehomogenized; the high-temperature waste heat flue gas generated by the indirect rotary drum heating furnace 3 is sent into a rotary drying drum 15 through a draught fan; salt-containing and alkali-containing waste gas generated in the indirect rotary drum heating furnace 3 is sent into a cyclone condenser 12 through an air extractor 11, the salt and alkali are cooled and then enter a salt storage bin 14 for collection, and the waste gas containing waste heat is sent into a rotary drying drum 15 through an induced draft fan for drying materials. The raw materials after the material preparation and homogenization in the rotary drying cylinder 15 are subjected to raw material checking, and the checked raw materials are sent to a raw material grinding machine 16 for grinding. And a part of the ground materials enter a rotary kiln 18 to be calcined at high temperature to obtain sulphoaluminate clinker, the other part of the ground materials enter a dry raw material bin 17 to be stored, the sulphoaluminate clinker and the desulfurized gypsum enter a material grinding machine 19 to be mixed and ground to obtain sulphoaluminate cement, dust-containing flue gas generated in the rotary kiln is dedusted by a deduster, and the sulphoaluminate cement is discharged after reaching the environmental protection standard.

The indirect rotary heating furnace conveys single aluminum ash waste, red mud, desulfurized gypsum and wet carbide slag materials into a rotary drying cylinder after indirect calcination denitrification, desalination and dealkalization treatment.

The denitrogenation and desalination waste gas generated by the indirectly heated aluminum ash is sent into a cyclone condenser.

The heated and indirectly denitrified aluminum ash contains a certain amount of heat, and is sent into a rotary drying cylinder to be mixed and heat-exchanged with raw materials such as red mud, desulfurized gypsum, carbide slag and the like, and meanwhile, the heat pumped from the rotary kiln is used for continuously exchanging heat with materials in the rotary drying cylinder, so that the multi-stage utilization of material energy is realized.

Flue gas containing dust and sulfur dioxide generated by the rotary kiln enters a rotary drying cylinder for drying raw materials and then enters a dust remover for removing dust.

The process flow is as follows:

1. feeding aluminum ash (the mass ratio of red mud, desulfurized gypsum, carbide slag and aluminum ash is 20:25:35:20) into an indirect rotary heater through an automatic feeding system, combusting natural gas through a low-nitrogen combustor, arranging gas nozzles in a crossed manner, uniformly feeding the combustion gas into a cavity, indirectly heating the aluminum ash in a roller, and gradually converting AlN into Al after the heating temperature reaches 700 ℃ through denitrification reaction₂O₃When the calcining temperature reaches 950 ℃, AlN in the aluminum ash is basically converted into alumina, salts such as sodium chloride, potassium chloride and the like in the aluminum ash are gasified, and finally the waste gas contains nitrogen, sodium chloride gas and potassium chloride gasAnd partial industrial solid waste decomposition gas.

2. The denitrified and desalted aluminum ash is sent into a rotary drying cylinder through a feed opening, mixed with other weighed raw materials of red mud, desulfurized gypsum and carbide slag for heat exchange, the water content is controlled below 5%, the mixture is discharged through an outlet of the rotary drying cylinder, mixed with a calibration material and sent into a pulverizer, and the raw material with the pulverized granularity smaller than 8 mu m enters a raw material bin. Table 1 shows the chemical composition change of the aluminum ash before and after pretreatment, and the reduction of chlorine, sodium and potassium elements is very obvious in the aluminum ash after the high-temperature calcination treatment at 950 ℃.

TABLE 1 composition change table before and after aluminum ash treatment

Composition (I)	Al₂O₃	MgO	SiO₂	CaO	SO₃	Na₂O	Fe₂O₃	TiO₂	K₂O	Cl
											After calcination	71.24	13.28	7.41	2.09	1.83	1.21	0.78	0.73	0.53	0.42
Raw aluminum ash	64.83	10.83	5.32	1.65	2.87	3.91	0.67	0.69	2.38	6.62

Fig. 2 to 3 are XRD (phase change XRD) graphs of mineral phases of the aluminum ash before and after heat treatment, which show that AlN, Al and NaCl of the aluminum ash calcined at 950 ℃ have no peak value basically, and the denitrification, desalination and oxidation processes of the aluminum ash can be considered to be complete.

3. And (3) conveying nitrogen, sodium chloride gas and potassium chloride gas generated by the treatment of the aluminum ash indirect heater into the rotary condenser through the air extractor, condensing and phase-changing the salt-containing gas to generate sodium chloride and potassium chloride salt crystals, dropping the sodium chloride and potassium chloride salt crystals into the salt storage pool through the feed opening of the rotary condenser, drying the filter pressing raw material through the dryer until natural moisture disappears, and conveying the filter pressing raw material into the storage chamber.

4. The well-matched raw material components and control parameters are SiO₂ 8wt％，CaO 42wt％，Al₂O₃ 29wt％，Fe₂O₃5wt％，SO₃16 wt%. Coefficient of basicity C_mIs 1.03.

5. And (3) conveying the raw materials in the storage bin into a calcination rotary kiln through a conveying device, carrying out the calcination process of the raw materials, conveying the raw materials into the rotary kiln, controlling the highest temperature in the kiln to be 1250 ℃, and carrying out high-temperature calcination for about 40 min.

6. And (3) burning the natural gas in the rotary kiln through a burner, wherein the excess air coefficient is controlled to be 1.1-1.15.

7. The raw materials in the rotary drying cylinder are dried by high-temperature flue gas generated in the rotary kiln until the moisture content is below 4 percent, and the minimum requirement of entering a mill is met.

8. The waste gas generated by the rotary drying cylinder reaches the environmental protection standard after passing through the dust remover and the desulfurization and denitrification device, and is discharged into the atmosphere.

9. The sulphoaluminate clinker generated in the rotary kiln is made of calcium sulphoaluminate (3 CaO.3Al)₂O₃·CaSO₄) And dicalcium silicate (2 CaO. SiO)₂) And iron phases as the major mineral phases. And finally, mixing the clinker with the desulfurized gypsum (the mass ratio of the clinker to the gypsum is 100:5), and grinding the mixture into cement in a cement mill. Table 3 shows the strength properties of the sulphoaluminate cement prepared from the total solid waste.

Table 3 strength properties test results

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing sulphoaluminate cement from whole solid waste of aluminum ash pretreatment is characterized in that the aluminum ash is heated to be not lower than 900 ℃ for heat treatment, the heat-treated aluminum ash is homogenized and mixed with red mud, desulfurized gypsum and carbide slag, the mixed material is dried by hot gas generated by the heat treatment, the dried material is ground in a raw powder proportioning manner, the ground material in the raw powder proportioning manner is calcined, and sulphoaluminate cement clinker is obtained; the aluminum ash comprises secondary aluminum ash or the aluminum ash is secondary aluminum ash.

2. The method for preparing sulphoaluminate cement from whole solid waste of aluminum ash pretreatment as claimed in claim 1, wherein the temperature of heat treatment is 900-950 ℃;

or the heating mode of the heat treatment aluminum ash is indirect heating.

3. The method for preparing sulfoaluminate cement from whole solid wastes generated by the pretreatment of aluminum ashes as recited in claim 1, wherein the flue gas generated by the heat treatment directly dries the materials, and the exhaust gas generated by the heat treatment of aluminum ashes is subjected to cyclone separation to dry the materials.

4. The method for preparing the sulphoaluminate cement from the whole solid waste of the aluminum ash pretreatment as recited in claim 1, wherein the mass ratio of the red mud, the desulfurized gypsum, the carbide slag and the aluminum ash is 15-25: 20-30: 30-40: 15-25;

or the moisture content of the dried material is less than 5 mass percent;

or the particle size of the material ground by the raw powder proportioning is less than 8 mu m.

5. The method for preparing sulfoaluminate cement from whole solid wastes of aluminum ash pre-treatment as claimed in claim 1, wherein the raw powder is proportioned into the ground component, SiO₂ 10～25wt％，CaO 20～30wt％，Al₂O₃ 20～30wt％，Fe₂O₃ 5～15wt％，SO₃ 20～30wt％。

6. The method for preparing sulfoaluminate cement from whole solid wastes of aluminum ash pretreatment as recited in claim 5, characterized in that the basicity coefficient C_m0.90 to 1.05.

7. The method for preparing sulphoaluminate cement from whole solid waste of aluminum ash pretreatment as claimed in claim 1, wherein the calcination temperature is 1230-1260 ℃;

or calcining the materials in the rotary kiln by using natural gas through a burner, and controlling the excess air coefficient to be 1.1-1.15.

8. The method for preparing sulphoaluminate cement from whole solid wastes pretreated by aluminum ash as claimed in claim 1, wherein the sulphoaluminate cement clinker is mixed with desulfurized gypsum and ground to obtain the sulphoaluminate cement.

9. A system for realizing the method for preparing the sulphoaluminate cement from the whole solid waste of the aluminum ash pretreatment according to any one of claims 1 to 8 comprises an indirect rotary drum heating furnace, a cyclone condenser, a dryer, a raw material pulverizer and a rotary kiln, wherein an inlet of the indirect rotary drum heating furnace is arranged to be connected with an aluminum ash source, a solid phase outlet of the indirect rotary drum heating furnace is connected with a material inlet of the dryer, a gas phase outlet of the indirect rotary drum heating furnace is connected with an inlet of the cyclone condenser, a gas phase outlet of the cyclone condenser is connected with a heat exchange gas inlet of the dryer, a material inlet of the dryer is also arranged to be connected with a red mud source, a desulfurized gypsum source and an acetylene sludge source, a material outlet of the dryer is connected with an inlet of the raw material pulverizer, and an outlet of the raw material.

10. The system for realizing the method for preparing the sulphoaluminate cement from the whole solid waste of the aluminum ash pretreatment as claimed in claim 9, comprising a salt storage bin, wherein the solid phase outlet of the cyclone condenser is connected with the salt storage bin;

or, the material pulverizer is included, and the outlet of the rotary kiln is connected with the material pulverizer;

or, the rotary kiln comprises a dust remover, and a flue gas outlet of the rotary kiln is connected with the dust remover;

or the dryer is a rotary dryer.