CN112159205A

CN112159205A - Iron tailing baked brick and preparation method thereof

Info

Publication number: CN112159205A
Application number: CN202010949592.7A
Authority: CN
Inventors: 周伟伦; 宁寻安; 王逸
Original assignee: Guangdong University of Technology
Current assignee: Guangdong University of Technology
Priority date: 2020-09-10
Filing date: 2020-09-10
Publication date: 2021-01-01

Abstract

The invention discloses an iron tailing baked brick and a preparation method thereof. The iron tailing sintered brick is prepared from the following raw materials in percentage by mass: 55-65% of iron tailings, 10-30% of fly ash and 10-30% of waste glass. The invention takes the solid waste as the raw material, provides a green sustainable development utilization way for the treatment and disposal of the solid waste, has no secondary pollution in the preparation process, and meets the requirements of clean production and green environmental protection. The sintered brick has the advantages of low water absorption, high strength and low heavy metal leaching concentration.

Description

Iron tailing baked brick and preparation method thereof

Technical Field

The invention relates to the field of harmless and comprehensive utilization of fixed wastes, and in particular relates to an iron tailing baked brick and a preparation method thereof.

Background

The traditional wall material is solid clay brick, a large amount of clay is consumed for firing the clay brick, and the main source of the clay is cultivated land. Therefore, in order to protect cultivated land, China forbids the production of solid clay bricks, so that the development of wall materials capable of sustainable development has great application prospect.

The iron tailings in China have the characteristics of large quantity, multiple types, small granularity, complex properties and the like, the accumulated stock is over 50 hundred million tons, the comprehensive utilization rate of the iron tailings is less than 20 percent, the iron tailings become the largest type of the accumulated stock in China, and the treatment and utilization are urgently needed to be accelerated. The fly ash is waste discharged by a thermal power plant taking coal as fuel, contains a large amount of silicon dioxide and aluminum oxide, and is a very good aluminosilicate raw material. The waste glass is a renewable resource, and if the waste glass is not properly disposed of, the waste glass not only has the risk of harming the environment, but also is a waste of resources. A small amount of glass can be recycled in China, and the rest of the glass is buried along with domestic garbage, so that a large amount of land resources are occupied. The method combines the characteristics that the three solid wastes can be used as building material raw materials, follows the principle of resource recycling, prepares the sintered bricks by the three solid wastes, responds to the national call for developing novel wall materials, and solves the problem of environmental pollution caused by the three solid wastes.

Research into the use of solid waste as a construction material has been a hot spot. Sludge, tailings, red mud, steel slag, fly ash and the like are proved to be used for preparing the baked bricks. Chinese invention patent CN101607815A (published time 12 months and 23 days 2009) discloses a sintered brick using fly ash and bentonite as raw materials, and the invention uses the fly ash and bentonite with large mixing amount to replace clay for making brick, thereby the fly ash sintered brick has the advantages of good heat preservation performance, good smoothness, difficult peeling and no crack, but has the problems of low compressive strength, high water absorption and excessive heavy metal leaching concentration. Chinese invention patent CN102153330B (published in 2013, 08.07) discloses a method for preparing a sintered brick by using boric acid, water glass and sludge as raw materials, wherein the sintered brick prepared by the method has low leaching concentration of chromium and arsenic, but insufficient compressive strength and high water absorption. Therefore, it is highly desirable to provide a sintered brick having high compressive strength, low water absorption, and low leaching concentration of heavy metals.

Disclosure of Invention

The invention aims to overcome the defects and shortcomings of low compressive strength, high water absorption and excessive heavy metal leaching concentration of the sintered brick produced by the prior art, and provides the iron tailing sintered brick. The strength of the iron tailing sintered brick can reach more than 100MPa, the iron tailing sintered brick is far higher than that of a common sintered brick, the water absorption rate is far lower than the threshold value of the national standard by 20%, the leaching concentration of heavy metal is low, and the potential harm to the environment is very low.

The invention also aims to provide a preparation method of the iron tailing baked brick.

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

the iron tailing sintered brick comprises the following raw materials in percentage by mass:

55% -65% of iron tailings;

10 to 30 percent of fly ash;

10 to 30 percent of waste glass;

wherein the waste glass is high borosilicate glass containing SiO₂80 to 97 percent by mass.

The iron tailings refer to residual solid wastes obtained after valuable metals which are easy to recover in iron ores are recovered, and Fe in the iron tailings₂O₃The content is 44% -55%, SiO₂25 to 30 percent of Al₂O₃The content is 13-15%.

The fly ash is fine ash collected from flue gas generated after coal combustion, the fly ash is main waste discharged by a coal-fired power plant, and SiO in the fly ash₂53-63% of Al₂O₃The content is 18-26%.

The raw materials of the invention are iron tailings, fly ash and waste glass, and compared with the traditional clay sintered brick, the raw materials are all solid wastes, thus meeting the requirement of comprehensive utilization of resources. Fe in iron tailings₂O₃Plays a role in fluxing in the sintering process and saves energy. The fly ash is a good framework material and can provide Al necessary for aluminosilicate for sintered bricks₂O₃And SiO₂And the iron tailings form good synergistic effect. The waste glass has high silicon content and can be sintered bricksProviding a silicon source of chemical composition Na₂O is a very good fluxing agent and can help to reduce the firing temperature of the green brick.

Preferably, the iron tailing sintered brick is prepared from the following raw materials in percentage by mass:

60% of iron tailings;

10-20% of fly ash;

20% -30% of waste glass;

wherein the waste glass is high borosilicate glass containing SiO₂The mass percentage is 85-97%.

A preparation method of an iron tailing baked brick comprises the following steps:

s1, grinding and sieving the dried iron tailings, the fly ash and the waste glass, and mixing the materials in proportion to obtain a dry material;

s2, adding water into the dry material, stirring and mixing to obtain a wet material, and placing the wet material in air for aging;

and S3, tabletting, drying and sintering the aged material at 1000-1200 ℃ to obtain the iron tailing sintered brick.

Preferably, in step S1, the milling screen is a 200 mesh screen. The contact area between the materials can be increased by ball milling through a 200-mesh screen, so that the materials are fully reacted, and the time required by sintering is reduced.

Preferably, in step S2, the water content of the mixed material is 10% to 20%. The water content of the mixed material is too low, and the plasticity of a brick blank is not good; too high, press molding becomes difficult.

More preferably, in step S2, the moisture content of the wet material is 15%.

Preferably, in step S2, the aging time is 24 h.

Preferably, in step S3, the tabletting pressure is 10MPa to 30 MPa.

More preferably, in step S3, the tabletting pressure is 20 MPa.

Preferably, in step S3, the drying temperature is 105 ℃. Drying before sintering can prevent cracking caused by too fast temperature rise.

Preferably, in step S3, the sintering temperature is 1100 ℃, and the sintering holding time is 2 h. The sintering temperature is too low, and the materials do not react or react incompletely; the temperature is too high, the sintered brick is easy to generate the overburning phenomenon, and the deformation is serious.

Preferably, in step S3, the heating rate of the sintering temperature is 6-8 ℃/min.

In the sintering process of the iron tailing sintered brick, a kaolinite phase in the fly ash and a quartz phase in the iron tailing react to generate a mullite phase, and the mullite phase is a common aluminosilicate structure, has a porous structure, is a main mineral framework of the sintered brick and endows the sintered brick with strength. The waste glass reaches the softening temperature at about 500 ℃ and is in a molten state, and the waste glass starts to flow into the mullite holes in a mobile phase manner to form a compact structure, so that the mechanical property of the sintered brick can be improved, and heavy metals can be further solidified in the internal structure of the sintered brick.

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

1. the invention effectively reduces the preparation cost of the baked brick by using the iron tailings, the fly ash and the waste glass as raw materials, solves the problem of environmental pollution caused by three pollutants, and realizes harmless and recycling treatment of solid wastes.

2. The invention has wide material source, simple raw materials and easy production practice, the strength of the produced sintered brick can reach more than 100MPa, which is far higher than that of the common sintered brick, the water absorption is low and is far lower than the requirement of national standard which is lower than 20%, the leaching concentration of heavy metal is low, and the potential harm to the environment is very low.

Drawings

FIG. 1 is an XRD pattern of iron tailing sintered bricks obtained in example 2, example 5 and comparative example 2.

FIG. 2 is an SEM picture of the iron tailing sintered brick obtained in example 5.

Detailed Description

In order to more clearly and completely describe the technical scheme of the invention, the invention is further described in detail by the specific embodiments, and it should be understood that the specific embodiments described herein are only used for explaining the invention, and are not used for limiting the invention, and various changes can be made within the scope defined by the claims of the invention.

The main chemical components of the raw materials used in the embodiments 1 to 12 of the present invention are shown in table 1 in mass percentage.

TABLE 1

Item	Fe₂O₃	SiO₂	Al₂O₃	K₂O	Na₂O	Others
							Iron tailings	53.78	28.13	13.33	0.86	-	3.90
Fly ash	6.36	57.01	25.33	2.93	0.88	7.49
							Waste glass	0.17	91.70	2.35	0.12	5.12	0.54

Examples 1 to 3

The iron tailing baked brick is prepared from the following raw materials in percentage by mass as shown in the following table 2:

TABLE 2

Item	Iron tailings (%)	Fly ash (%)	Waste glass (%)
				Example 1	60	30	10
Example 2	60	20	20
				Example 3	60	10	30

The preparation method of the iron tailing baked brick in the embodiment 1 comprises the following steps:

s1, drying iron tailings, fly ash and waste glass in a drying oven at 105 ℃ for 24 hours respectively, cooling, grinding in a ball mill for 1 hour, sieving through a 200-mesh sieve to obtain powder, and mixing the powder for 30min in proportion to obtain a dry material;

s2, adding water into the dry material to enable the water content of the material to be 10%, stirring and mixing the material in a ball milling tank for 30min to obtain a wet material, and aging the wet material in air for 24 h;

and S3, pressing the aged material into a tablet machine under 10MPa for molding, then putting the molded brick blank into a drying box, drying at 105 ℃ for 24h to obtain a dry blank, finally sintering at 1000 ℃ for 2h at a heating rate of 6 ℃/min, and cooling to obtain the iron tailing sintered brick.

The preparation method of the iron tailing baked brick described in the examples 2 and 3 is the same as that of the example 1.

Example 4

The raw material composition of the iron tailing baked brick is the same as that in example 1, and the preparation method of the iron tailing baked brick is basically the same as that in example 1, except that the water content of the material is 15%, the tabletting forming pressure is 20MPa, the sintering temperature is 1100 ℃, and the heating rate is 8 ℃/min.

Example 5

The raw material composition of the iron tailing baked brick is the same as that in example 2, and the preparation method of the iron tailing baked brick is the same as that in example 4.

Example 6

The raw material composition of the iron tailing baked brick is the same as that in example 3, and the preparation method of the iron tailing baked brick is the same as that in example 4.

Example 7

The raw material composition of the iron tailing baked brick is the same as that of example 1, the preparation method of the iron tailing baked brick is basically the same as that of example 5, and the difference is that the sintering temperature is 1200 ℃.

Example 8

The raw material composition of the iron tailing baked brick is the same as that of example 2, the preparation method of the iron tailing baked brick is basically the same as that of example 5, and the difference is that the sintering temperature is 1200 ℃.

Example 9

The raw material composition of the iron tailing baked brick is the same as that of example 3, the preparation method of the iron tailing baked brick is basically the same as that of example 5, and the difference is that the sintering temperature is 1200 ℃.

Example 10

The raw material composition of the iron tailing baked brick is the same as that in example 5, and the preparation method of the iron tailing baked brick is basically the same as that in example 5, except that the water content of the material is 20%, the tabletting forming pressure is 30MPa, the sintering temperature is 1200 ℃, and the heating rate is 8 ℃/min.

Example 11

The iron tailing baked brick is prepared from the following raw materials in percentage by mass: 55% of iron tailings, 20% of fly ash and 25% of waste glass; the preparation method of the iron tailing baked brick is the same as that of the embodiment 5.

Example 12

The iron tailing baked brick is prepared from the following raw materials in percentage by mass: 65% of iron tailings, 20% of fly ash and 15% of waste glass; the preparation method of the iron tailing baked brick is the same as that of the embodiment 5.

Comparative example 1

The iron tailing baked brick is prepared from the following raw materials in percentage by mass:

60% of iron tailings;

20% of fly ash;

20% of sulfur-containing sludge of mine drainage plants;

the sludge refers to sludge obtained after filter pressing treatment of a plate frame of a mine drainage plant, and the main components of the sludge are rainwater in a mine and a tailing pond and tailings carried by mineral processing wastewater flowing through a refuse dump and a mud blocking pond and mine soil.

The preparation method of the iron tailing baked brick in the comparative example 1 is the same as that of the example 5.

Comparative example 2

The raw material composition of the iron tailing baked brick is the same as that of example 5, the preparation method of the iron tailing baked brick is basically the same as that of example 5, and the difference is that the sintering temperature is 900 ℃.

Comparative example 3

The raw material composition of the iron tailing baked brick is the same as that of example 1, the preparation method of the iron tailing baked brick is basically the same as that of example 5, and the difference is that the sintering temperature is 900 ℃.

Comparative example 4

The raw material composition of the iron tailing baked brick is the same as that of example 3, the preparation method of the iron tailing baked brick is basically the same as that of example 5, and the difference is that the sintering temperature is 900 ℃.

Comparative example 5

60% of iron tailings;

20% of fly ash;

20% of common glass;

SiO in the common glass₂The content is 72%.

Comparative example 5 the preparation method of the iron tailing baked brick is the same as that of example 5.

Performance testing and results evaluation

The iron tailing sintered bricks obtained in example 2, example 5 and comparative example 2 were examined by an X-ray diffractometer of Bruker D8 model of Bruker, germany, and the examination results are shown in fig. 1. Microstructure detection of the iron tailing sintered brick prepared in example 5 was performed by a Zeiss Sigma 300 type scanning electron microscope, and the detection result is shown in fig. 2.

It can be seen from fig. 1 that the characteristic peaks of quartz and kaolinite gradually decrease and the characteristic peak of mullite gradually increases with the increase of sintering temperature, indicating that the kaolinite phase reacts with the quartz phase to form the mullite phase during sintering.

It can be seen from fig. 2 that the surface of the sintered brick has many small pores, and a lot of liquid phase glass is filled into the pore structure, so that heavy metals are effectively solidified in the internal structure of the iron tailing sintered brick.

And (3) performing performance detection on the iron tailing sintered bricks prepared in the examples 1-12 and the comparative examples 1-5, wherein the detection method of the compressive strength and the detection method of the water absorption rate refer to GB/T2542-2012 and GB5085.3-2007 respectively. The standard requirements and the detection results of the compressive strength and the water absorption of the iron tailing sintered brick are shown in the table 3, and the standard requirements refer to GB/T5101-2003.

The detection result of the leaching performance of the heavy metal is shown in a table 4, and the standard requirement refers to GB 5085.3-2007.

TABLE 3

Item	Compressive strength (MPa)	Water absorption (%)
			Standard requirements	≥10	≤20
Example 1	30.51	15.63
			Example 2	67.59	12.74
Example 3	105.53	10.36
			Example 4	112.66	10.04
Example 5	124.61	3.11
			Example 6	101.51	1.59
Example 7	54.24	2.56
			Example 8	51.04	1.40
Example 9	80.54	1.35
			Example 10	51.13	2.72
Example 11	89.25	2.12
			Example 12	82.36	3.47
Comparative example 1	16.12	18.32
			Comparative example 2	19.43	18.86
Comparative example 3	11.05	20.25
			Comparative example 4	29.11	16.67
Comparative example 5	25.36	16.42

TABLE 4

As can be seen from the above detection results table 3, the compressive strength and the water absorption of the iron tailing sintered bricks obtained in examples 1 to 10 can simultaneously satisfy the national standard requirements, wherein the compressive strength of the iron tailing sintered bricks obtained in examples 3 to 6 is more than 100MPa, which is much higher than that of the common sintered bricks, the water absorption of the iron tailing sintered bricks obtained in example 6 is as low as 1.59%, which is much lower than that of the national standard, which is much lower than 20%, and the compressive strength of the iron tailing sintered bricks obtained in comparative examples 1 to 5 is lower than that of the iron tailing sintered bricks obtained in examples, and the water absorption is higher. The heavy metal leaching concentration detection results in table 4 show that the leaching concentrations of copper, zinc, lead and cadmium in the iron tailing baked bricks prepared in all the examples are far lower than the national standard requirements, and the potential risk to the environment is extremely low.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. The iron tailing baked brick is characterized by comprising the following raw materials in percentage by mass:

55% -65% of iron tailings;

10 to 30 percent of fly ash;

10 to 30 percent of waste glass;

wherein the waste glass is high borosilicate glass containing SiO₂The mass percentage is 80-97%.

2. The iron tailing baked brick as claimed in claim 1, which is prepared from the following raw materials in percentage by mass:

60% of iron tailings;

10-20% of fly ash;

20% -30% of waste glass;

3. The method for preparing the iron tailing baked brick as claimed in any one of the claims 1 or 2, which comprises the following steps:

4. The method for preparing the iron tailing baked brick as claimed in claim 3, wherein in the step S1, the grinding and screening are performed by ball milling and then screening with a 200-mesh screen.

5. The method for preparing the iron tailing baked brick as claimed in claim 3, wherein in step S2, the water content of the mixed material is 10-20%.

6. The method for preparing the iron tailing baked brick as claimed in any one of claims 3 or 5, wherein in the step S2, the moisture content of the wet material is 15%.

7. The method for preparing the iron tailing baked brick as claimed in claim 3, wherein in the step S3, the tabletting pressure is 10MPa to 30 MPa.

8. The method for preparing the iron tailing baked brick as claimed in any one of the claims 3 or 7, wherein in the step S3, the tabletting pressure is 20 MPa.

9. The method for preparing the iron tailing baked brick as claimed in claim 3, wherein in the step S3, the sintering temperature is 1100 ℃, and the sintering holding time is 2 hours.

10. The method for preparing the iron tailing baked brick as claimed in claim 3, wherein in the step S3, the temperature rise rate of the sintering temperature is 6 ℃/min to 8 ℃/min.