Iron tailing-based negative carbon artificial aggregate and preparation method thereof

Abstract

The invention provides an iron tailing-based negative carbon artificial aggregate and a preparation method thereof. The iron tailing-based negative carbon artificial aggregate comprises the following materials: 16 parts of water, 50-90 parts of iron tailing powder, 10-30 parts of cement and 0-40 parts of other solid wastes. The other solid wastes at least comprise one of concrete recycled micro powder, steel slag powder and carbide slag powder. According to the invention, the raw materials can be directly used for batch production of the artificial aggregate only by drying treatment, and the aggregate production process is simple in steps. In addition, the utilization amount of the iron tailing powder can reach 90% at most, the resource utilization of the iron tailing powder is greatly improved, and meanwhile, the aggregate still has good physical properties. Meanwhile, the concrete recycled micro powder, the carbide slag powder, the steel slag powder and other solid wastes can be cooperatively utilized, and comprehensive utilization of solid waste recycling is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber-reinforced cement-based composites, and particularly relates to an iron tailing-based negative-carbon artificial aggregate. Background Art

[0002] The iron and steel industry is the foundation of the development of China's national economy, and iron ore is an important raw material for the iron and steel industry. However, the endowment of iron ore resources in China is poor, the gap between supply and demand of iron ore is expanding, and the activity and utilization rate of tailings after ore dressing are low, resulting in a gradual increase in iron tailing waste, accounting for about 41.5% of the total tailings. At present, due to the optimization of the ore dressing process and the upgrading of the flotation process, the particle size of iron tailings is getting smaller and smaller, resulting in a gradual increase in the proportion of iron tailing powder. The large accumulation of iron tailings not only occupies a large amount of land and consumes a large amount of human resources, but also seriously affects the ecological environment. At present, there is no relatively mature process for the large-scale utilization of iron tailing powder. The production process of traditional artificial aggregates is complex, accompanied by a large amount of carbon emissions. Summary of the Invention

[0003] The present invention provides an iron tailing-based negative-carbon artificial aggregate and a preparation method thereof. Through scientific mix ratio design and reasonable production process, an artificial aggregate with a high carbon sequestration rate and high strength is prepared, realizing the effective utilization of iron tailings, and at the same time simplifying the preparation process and enabling mass production.

[0004] The present invention provides an iron tailing-based negative-carbon artificial aggregate, including the following materials: 16 parts of water, 50 - 90 parts of iron tailing powder, 10 - 30 parts of cement, and 0 - 40 parts of other solid wastes; the other solid wastes include at least one of concrete recycled fine powder, steel slag powder, and carbide slag powder.

[0005] Further, the specific surface area of the iron tailing powder is 232.0 m 2 / kg.

[0006] Further, the iron tailing powder includes 45% - 55% of SiO2, 15% - 20% of Fe2O3, 10% - 15% of A12O3, and 5% - 10% of CaO.

[0007] Further, the specific surface area of the concrete recycled fine powder is 625.7 m 2 / kg.

[0008] Further, the particle size of the steel slag powder is less than 150 um, and the particle size of the carbide slag powder is less than 150 um.

[0009] Furthermore, the density of the steel slag powder is 3.18 g / cm 3 .

[0010] Furthermore, the CaO content in the carbide slag powder is not less than 70%.

[0011] On the other hand, the present invention also discloses a preparation method of the above-mentioned iron tailing-based carbon-negative artificial aggregate, characterized in that the preparation method includes:

[0012] S1. Mix various solid raw materials of the iron tailing-based carbon-negative artificial aggregate, stir, and add water.

[0013] S2. Increase the stirring speed and maintain stirring under high-speed conditions.

[0014] S3. Granulate and cure to obtain the iron tailing-based carbon-negative artificial aggregate.

[0015] Furthermore, the S1 includes:

[0016] S101. Put the solid raw materials into a stirring pot and dry stir for 30 s.

[0017] S102. Continue to maintain this stirring speed and slowly add the weighed water within 30 s.

[0018] Furthermore, the S3 includes:

[0019] S301. Turn on the double-roll extrusion granulator with the process parameters set, and pour the mixed materials in the stirring pot into it at one time for granulation. After granulation, obtain the prefinished product of ellipsoidal artificial aggregate.

[0020] S302. Put the prefinished artificial aggregate on an iron tray and place it under natural conditions, and cover it with a film for pre-curing for 2 - 6 h.

[0021] S303. After pre-curing, screen through a 4.75 mm sieve, and then immediately put it into a pressure carbonization kettle, and introduce CO2 with a concentration of 90 - 99.9% to make the internal gas pressure reach 0.5 - 2 bar, and carbonize for 3 - 10 h.

[0022] S304. After carbonization curing, immediately carry out water curing, the water temperature is 10 - 30 °C, and cure for 3 - 28 days to obtain the iron tailing-based carbon-negative artificial aggregate.

[0023] The present invention only needs to dry the raw materials and can be directly used for the batch production of artificial aggregates, and the aggregate production process steps are simple. In addition, the utilization rate of the iron tailing powder in the present invention can reach up to 90%, which greatly improves the resource utilization of the iron tailing powder. At the same time, the aggregate still has good physical properties. Meanwhile, the present invention can synergistically utilize other solid wastes such as concrete recycled fine powder, carbide slag powder, and steel slag powder to realize the comprehensive utilization of solid waste resourceization. Specific Embodiments

[0024] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0025] The embodiments of the present invention disclose an iron tailing-based negative-carbon artificial aggregate and a preparation method thereof. To make the purpose, technical solution and effect of the present invention clearer and more definite, the following further details the present invention.

[0026] The present invention provides a negative-carbon artificial aggregate, which comprises the following materials: 16 parts of water, 50-90 parts of iron tailing powder, 10-30 parts of cement, and 0-40 parts of other solid wastes; the other solid wastes include at least one of concrete recycled fine powder, steel slag powder, and carbide slag powder.

[0027] Optionally, the specific surface area of the iron tailing powder is 232.0 m 2 / kg.

[0028] Optionally, the iron tailing powder comprises 45%-55% of SiO2, 15%-20% of Fe2O3, 10%-15% of A12O3, and 5%-10% of CaO.

[0029] Optionally, the specific surface area of the concrete recycled fine powder is 625.7 m 2 / kg.

[0030] Optionally, the particle size of the steel slag powder is less than 150 um, and the particle size of the carbide slag powder is less than 150 um.

[0031] Particularly, the density of the steel slag powder is 3.18 g / cm 3

[0032] Particularly, the CaO content in the carbide slag powder is not less than 70%.

[0033] On the other hand, the present invention also discloses a preparation method of the above-mentioned iron tailing-based negative-carbon artificial aggregate, comprising:

[0034] S1. Take each solid raw material of the iron tailing-based negative-carbon artificial aggregate, mix and stir, and add water;

[0035] S2. Increase the stirring speed and keep stirring under high-speed conditions;

[0036] S3. Granulate and cure to obtain the iron tailing-based negative-carbon artificial aggregate.

[0037] Optionally, S1 includes:

[0038] S101. Put the solid raw materials into a stirring pot and dry stir for 30 s;

[0039] S102. Keep this stirring speed and slowly add the weighed water within 30 s.

[0040] Optionally, the said S3 includes:

[0041] S301. Turn on the pair-roll extrusion granulator with the process parameters set, and pour the mixed materials in the stirring pot at one time for granulation. After granulation, obtain the prefinished ellipsoidal artificial aggregate;

[0042] S302. Load the prefinished artificial aggregate on an iron tray and place it under natural conditions, and carry out pre-curing by film covering for 2 - 6 h;

[0043] S303. After the pre-curing ends, sieve through a 4.75 mm sieve, then immediately put it into a pressure carbonization kettle, and introduce CO2 with a concentration of 90 - 99.9% to make the internal gas pressure reach 0.5 - 2 bar, and carbonize for 3 - 10 h;

[0044] S304. After the carbonization curing ends, immediately carry out water curing, the water temperature is 10 - 30 °C, and cure until 3 - 28 days later to obtain the iron tailings-based negative-carbon artificial aggregate.

[0045] The following further explains the iron tailings-based negative-carbon artificial aggregate and its preparation method proposed by the present invention through specific embodiments:

[0046] Example 1

[0047] An iron tailings-based negative-carbon artificial aggregate and its preparation method, the specific steps are as follows;

[0048] Step 1. Place the iron tailings powder in a 60 °C blast drying oven and dry it for 96 h to ensure complete drying, then take it out for subsequent use;

[0049] Step 2. Weigh 1400 parts of iron tailings powder, 600 parts of cement, and 320 parts of water by mass;

[0050] Step 3. Put the solid raw materials into the stirring pot and dry stir at the speed of gear 2 for 30 s. After that, keep this stirring speed and slowly add the weighed water within 30 s;

[0051] Step 4. After that, slowly adjust the stirring speed from the speed of gear 2 to the speed of gear 8, and stir at this high speed for 30 s. After that, stop stirring and clean the mixed materials adhering to the inner wall of the stirring pot within 15 s;

[0052] Step 5. After cleaning, immediately continue to stir at a high speed at the stirring speed of gear 8 for 30 s. After that, clean the mixed materials adhering to the inner wall of the stirring pot;

[0053] Step 6. After the cleaning is completed, immediately turn on the double-roll extrusion granulator with the process parameters set (the process parameters of the double-roll extrusion granulator are: motor power: 11 KW, granule size of the driving wheel: 10 mm, rotational speed of the driving wheel: 55 r / min, clearance of the driving wheel: 0.3 - 1 mm), and pour the mixed materials in the mixing pot into it all at once for granulation. After the granulation is completed, an ellipsoidal artificial aggregate preform is obtained;

[0054] Step 7. Place the preformed artificial aggregate in an iron tray and place it under natural conditions, and carry out pre-curing for 4 h with film covering;

[0055] Step 8. After the pre-curing is completed, sieve through a 4.75-mm sieve, and then immediately put it into a pressure carbonization kettle, and introduce CO2 with a concentration of 99.5% to make the internal gas pressure reach 1 bar, and carbonize for 4 h;

[0056] Step 9. After the carbonization curing is completed, immediately carry out water curing at a water temperature of 24 °C, and cure until the specified age to obtain iron tailings-based negative-carbon artificial aggregate.

[0057] The obtained finished aggregate is subjected to physical property tests according to GB / T 1743.1 - 2010 "Lightweight Aggregates and Their Test Methods". The test results of the artificial aggregate at 7 d are shown in Table 1:

[0058] Table 1 is the physical properties of the aggregate in Example 1

[0059] Single-particle strength (MPa) Apparent density (kg / m3) 24-hour water absorption rate (%) Unit net carbon fixation amount (%) Example 1 2.54 2060.88 12.76 5.07

[0060] Example 2

[0061] An iron tailings-based negative-carbon artificial aggregate and its preparation method are as follows;

[0062] Step 1. Place the iron tailings powder in a 60 °C blast drying oven and dry it for 96 h to ensure complete drying, and take it out for subsequent use;

[0063] Step 2. Weigh 1000 parts of iron tailings powder, 800 parts of concrete recycled micro powder, 200 parts of cement and 320 parts of water by mass;

[0064] Step 3. Put the solid raw materials into the mixing pot and dry mix them at a speed of gear 2 for 30 s. After that, continue to maintain this mixing speed and slowly add the weighed water within 30 s;

[0065] Step 4. After that, slowly adjust the mixing speed from the speed of gear 2 to gear 8, and high-speed mix at this mixing speed for 30 s. After that, stop mixing and clean the mixed materials adhering to the inner wall of the mixing pot within 15 s;

[0066] Step 5. After the cleaning is completed, immediately continue high-speed stirring at a stirring speed of 8 for 30 s. After completion, clean the mixed materials adhering to the inner wall of the stirring pot;

[0067] Step 6. After the cleaning is completed, immediately turn on the pair-roll extrusion granulator with the set process parameters (the process parameters of the pair-roll extrusion granulator are: motor power: 11 KW, granule size of the driving wheel: 10 mm, rotational speed of the driving wheel: 55 r / min, gap of the driving wheel: 0.3 - 1 mm), and pour the mixed materials in the stirring pot all at once for granulation. After the granulation is completed, an ellipsoidal artificial aggregate pre-product is obtained;

[0068] Step 7. Load the pre-product artificial aggregate onto an iron tray and place it under natural conditions, and carry out pre-curing for 4 h with film covering;

[0069] Step 8. After the pre-curing is completed, sieve through a 4.75-mm sieve, and then immediately put it into a pressurized carbonization kettle, and introduce CO2 with a concentration of 99.5% to make the internal gas pressure reach 1 bar, and carbonize for 4 h;

[0070] Step 9. After the carbonization curing is completed, immediately carry out water curing at a water temperature of 24 °C, and cure until the specified age to obtain the iron tailing-based negative-carbon artificial aggregate.

[0071] Conduct physical property tests on the obtained finished aggregate according to GB / T 1743.1 - 2010 "Lightweight Aggregates and Their Test Methods". The test results of the artificial aggregate at 7 d are shown in Table 2:

[0072] Table 2 shows the physical properties of the aggregate in Example 2

[0073] Single-particle strength (MPa) Apparent density (kg / m3) 24-hour water absorption rate (%) Unit total carbon fixation amount (%) Example 2 1.72 1996.67 15.95 6.13

[0074] Example 3

[0075] An iron tailing-based negative-carbon artificial aggregate and its preparation method are as follows;

[0076] Step 1. Place the iron tailing powder in a 60 °C blast drying oven and dry it for 96 h to ensure complete drying, and take it out for subsequent use;

[0077] Step 2. Weigh 1000 parts of iron tailing powder, 800 parts of steel slag powder, 200 parts of cement, and 320 parts of water by mass;

[0078] Step 3. Put the solid raw materials into the stirring pot and dry stir at a speed of 2 for 30 s. After completion, continue to maintain this stirring speed, and slowly add the weighed water within 30 s;

[0079] After step 4, slowly adjust the stirring speed from the second gear speed to the eighth gear, and stir at this high speed for 30 s. After that, stop stirring and clean the mixed materials adhering to the inner wall of the stirring pot within 15 s;

[0080] After the cleaning is completed, immediately continue to stir at a high speed of the eighth gear for 30 s. After that, clean the mixed materials adhering to the inner wall of the stirring pot;

[0081] After the cleaning is completed, immediately open the double-roll extrusion granulator with the process parameters set (the process parameters of the double-roll extrusion granulator are: motor power: 11 KW, granule size of the driving wheel: 10 mm, rotational speed of the driving wheel: 55 r / min, clearance of the driving wheel: 0.3 - 1 mm), and pour the mixed materials in the stirring pot all at once for granulation. After the granulation is completed, an ellipsoidal prefabricated artificial aggregate is obtained;

[0082] Step 7. Place the prefabricated artificial aggregate on an iron tray and place it under natural conditions, and cover it with a film for 4 h of pre-curing;

[0083] After the pre-curing is completed, sieve through a 4.75 mm sieve, and then immediately put it into a pressure carbonization kettle, and introduce CO₂ with a concentration of 99.5% to make the internal gas pressure reach 1 bar, and carbonize for 4 h;

[0084] After the carbonization curing is completed, immediately carry out water curing. The water temperature is 24 °C, and after curing to the specified age, iron tailings-based negative-carbon artificial aggregate is obtained.

[0085] The obtained finished aggregate is subjected to physical property tests according to GB / T 1743.1 - 2010 "Lightweight Aggregates and Their Test Methods". The test results of the artificial aggregate at 7 d are shown in Table 3:

[0086] Table 3 shows the physical properties of the aggregate in Example 3

[0087] Single-particle strength (MPa) Apparent density (kg / m3) 24-hour water absorption rate (%) Unit total carbon fixation amount (%) Example 3 1.14 2164.29 13.47 7.14

[0088] Example 4

[0089] An iron tailings-based negative-carbon artificial aggregate and its preparation method are as follows;

[0090] Step 1. Place the iron tailings powder in a 60 °C forced-air drying oven and dry it for 96 h to ensure complete drying, then take it out for subsequent use;

[0091] Step 2. Weigh 1000 parts of iron tailings powder, 800 parts of carbide slag powder, 200 parts of cement and 320 parts of water by mass;

[0092] Step 3. Put the solid raw materials into the mixing pot and dry mix at speed 2 for 30 s. After that, keep this mixing speed and slowly add the weighed water within 30 s.

[0093] Step 4. After completion, slowly adjust the mixing speed from speed 2 to speed 8 and high-speed mix at this speed for 30 s. After completion, stop mixing and clean the mixed materials adhering to the inner wall of the mixing pot within 15 s.

[0094] Step 5. After cleaning, immediately continue high-speed mixing at speed 8 for 30 s. After completion, clean the mixed materials adhering to the inner wall of the mixing pot.

[0095] Step 6. After cleaning, immediately turn on the pair-roll extrusion granulator with the set process parameters (the process parameters of the pair-roll extrusion granulator are: motor power: 11 KW, granule size of the driving wheel: 10 mm, rotational speed of the driving wheel: 55 r / min, gap of the driving wheel: 0.3 - 1 mm), and pour the mixed materials in the mixing pot into it at one time for granulation. After granulation, an ellipsoidal prefinished artificial aggregate is obtained.

[0096] Step 7. Place the prefinished artificial aggregate on an iron tray and place it under natural conditions, and carry out pre-curing for 4 h with film covering.

[0097] Step 8. After pre-curing, screen through a 4.75 mm sieve, and then immediately put it into a pressure carbonization kettle, and introduce CO2 with a concentration of 99.5% to make the internal gas pressure reach 1 bar, and carbonize for 4 h.

[0098] Step 9. After carbonization curing, immediately carry out water curing. The water temperature is 24 °C, and cure until the specified age to obtain iron tailings-based negative-carbon artificial aggregate.

[0099] The obtained finished aggregate is subjected to physical property tests according to GB / T 1743.1 - 2010 "Lightweight Aggregates and Their Test Methods". The test results of the artificial aggregate at 7 d are shown in Table 4:

[0100] Table 4 is the physical properties of the aggregate in Example 4

[0101] Single-particle strength (MPa) Apparent density (kg / m3) 24-hour water absorption rate (%) Unit total carbon fixation amount (%) Example 4 0.68 1783.60 19.49 5.93

[0102] Example 5

[0103] An iron tailings-based negative-carbon artificial aggregate and its preparation method are as follows;

[0104] Step 1. Place the iron tailings powder in a 60 °C blast drying oven and dry it for 96 h to ensure complete drying, and take it out for subsequent use.

[0105] Step 2. Weigh 1400 parts of iron tailings powder, 200 parts of recycled concrete fine powder, 400 parts of cement and 320 parts of water by mass;

[0106] Step 3. Put the solid raw materials into the mixing pot and dry mix them at a speed of gear 2 for 30 s. After that, continue to maintain this mixing speed and slowly add the weighed water within 30 s;

[0107] Step 4. After that, slowly adjust the mixing speed from gear 2 to gear 8 and high-speed mix them at this mixing speed for 30 s. After that, stop mixing and clean the mixed materials adhering to the inner wall of the mixing pot within 15 s;

[0108] Step 5. After cleaning, immediately continue to high-speed mix them at a mixing speed of gear 8 for 30 s. After that, clean the mixed materials adhering to the inner wall of the mixing pot;

[0109] Step 6. After cleaning, immediately turn on the pair-roll extrusion granulator with the set process parameters (the process parameters of the pair-roll extrusion granulator are: motor power: 11 KW, granule size of the driving wheel is 10 mm, rotation speed of the driving wheel is 55 r / min, gap of the driving wheel is 0.3 - 1 mm), and pour the mixed materials in the mixing pot into it all at once for granulation. After granulation, obtain the prefinished ellipsoidal artificial aggregate;

[0110] Step 7. Put the prefinished artificial aggregate on an iron tray and place it under natural conditions, and carry out pre-curing for 4 h with film covering;

[0111] Step 8. After pre-curing, sieve it through a 4.75 mm sieve, and then immediately put it into a pressure carbonization kettle, and introduce CO₂ with a concentration of 99.5% to make the internal gas pressure reach 1 bar, and carbonize for 4 h;

[0112] Step 9. After carbonization curing, immediately carry out water curing, the water temperature is 24 °C, and cure until the specified age to obtain the iron tailings-based negative-carbon artificial aggregate.

[0113] Conduct physical property tests on the obtained finished aggregate according to GB / T 1743.1 - 2010 "Lightweight Aggregates and Their Test Methods". The test results of the artificial aggregate at 7 d are shown in Table 5:

[0114] Table 5 is the physical properties of the aggregate in Example 5

[0115] Single-particle strength (MPa) Apparent density (kg / m3) 24-hour water absorption rate (%) Unit net carbon fixation amount (%) Example 5 1.18 1987.29 14.48 5.15

[0116] Example 6

[0117] An iron tailings-based negative-carbon artificial aggregate and its preparation method are as follows;

[0118] Step 1. Place the iron tailings powder in a blast drying oven at 60 °C for 96 h to ensure complete drying, and take it out for subsequent use;

[0119] Step 2. Weigh 1200 parts of iron tailings powder, 400 parts of recycled concrete fine powder, 400 parts of cement, and 320 parts of water by mass;

[0120] Step 3. Put the solid raw materials into the mixing pot and dry mix at a speed of 2 for 30 s. After that, continue to maintain this mixing speed and slowly add the weighed water within 30 s;

[0121] Step 4. After that, slowly adjust the mixing speed from speed 2 to speed 8 and high-speed mix at this mixing speed for 30 s. After that, stop mixing and clean the mixed materials adhering to the inner wall of the mixing pot within 15 s;

[0122] Step 5. After cleaning, immediately continue to high-speed mix at a mixing speed of 8 for 30 s. After that, clean the mixed materials adhering to the inner wall of the mixing pot;

[0123] Step 6. After cleaning, immediately turn on the double-roller extrusion granulator with the set process parameters (the process parameters of the double-roller extrusion granulator are: motor power: 11 KW, granule size of the driving wheel: 10 mm, rotation speed of the driving wheel: 55 r / min, gap of the driving wheel: 0.3 - 1 mm), and pour the mixed materials in the mixing pot into it at one time for granulation. After granulation, an ellipsoidal artificial aggregate preform is obtained;

[0124] Step 7. Place the preformed artificial aggregate in an iron tray and place it under natural conditions, and cover it with a film for 4 h of pre-curing;

[0125] Step 8. After pre-curing, pass through a 4.75 mm sieve, and then immediately put it into a pressure carbonization kettle, and introduce CO2 with a concentration of 99.5% to make the internal gas pressure reach 1 bar, and carbonize for 4 h;

[0126] Step 9. After carbonization curing, immediately carry out water curing. The water temperature is 24 °C, and cure until the specified age to obtain iron tailings-based negative carbon artificial aggregate.

[0127] Conduct physical property tests on the obtained finished aggregate according to GB / T 1743.1 - 2010 "Lightweight Aggregates and Their Test Methods". The test results of the artificial aggregate at 7 d are shown in Table 4:

[0128] Table 6 shows the physical properties of the aggregate in Example 6

[0129] Single-particle strength (MPa) Apparent density (kg / m3) 24-hour water absorption rate (%) Unit total carbon fixation amount (%) Example 6 1.92 1964.85 14.77 4.90

[0130] Example 7

[0131] A kind of iron tailings-based negative-carbon artificial aggregate and its preparation method, the specific steps are as follows;

[0132] Step 1. Place the iron tailings powder in a blast drying oven at 60 °C and dry it for 96 h to ensure complete drying, then take it out for subsequent use;

[0133] Step 2. Weigh 1000 parts of iron tailings powder, 600 parts of concrete recycled fine powder, 400 parts of cement and 320 parts of water by mass;

[0134] Step 3. Put the solid raw materials into the mixing pot and dry mix at a speed of 2 for 30 s. After that, continue to maintain this mixing speed and slowly add the weighed water within 30 s;

[0135] Step 4. After that, slowly adjust the mixing speed from speed 2 to speed 8 and high-speed mix at this mixing speed for 30 s. After that, stop mixing and clean the mixed materials adhering to the inner wall of the mixing pot within 15 s;

[0136] Step 5. After cleaning, immediately continue to high-speed mix at a mixing speed of 8 for 30 s. After that, clean the mixed materials adhering to the inner wall of the mixing pot;

[0137] Step 6. After cleaning, immediately turn on the double-roll extrusion granulator with the process parameters set (the process parameters of the double-roll extrusion granulator are: motor power: 11 KW, granule size of the driving wheel is 10 mm, rotational speed of the driving wheel is 55 revolutions per minute, and the gap of the driving wheel is 0.3 - 1 mm), and pour the mixed materials in the mixing pot into it for granulation at one time. After granulation, obtain the prefabricated ellipsoidal artificial aggregate;

[0138] Step 7. Place the prefabricated artificial aggregate on an iron tray and place it under natural conditions, and cover it with a film for 4 h of pre-curing;

[0139] Step 8. After pre-curing, sieve through a 4.75 mm sieve, and then immediately put it into a pressure carbonization kettle, and introduce CO2 with a concentration of 99.5% to make the internal gas pressure reach 1 bar and carbonize for 4 h;

[0140] Step 9. After carbonization curing, immediately carry out water curing. The water temperature is 24 °C, and cure until the specified age to obtain the iron tailings-based negative-carbon artificial aggregate.

[0141] Conduct physical property tests on the obtained finished aggregate according to GB / T 1743.1 - 2010 "Lightweight Aggregates and Their Test Methods". The test results of the artificial aggregate at 28 d are shown in Table 4:

[0142] Table 7 shows the physical properties of the aggregate in Example 7

[0143] Single-particle strength (MPa) Apparent density (kg / m3) 24-hour water absorption rate (%) Unit total carbon fixation amount (%) Example 7 3.01 2005.82 14.57 5.58

[0144] Example 8

[0145] A kind of iron tailings-based negative-carbon artificial aggregate and its preparation method, the specific steps are as follows;

[0146] Step 1. Place the iron tailings powder in a blast drying oven at 60 °C and dry it for 96 h to ensure complete drying, then take it out for subsequent use;

[0147] Step 2. Weigh 1000 parts of iron tailings powder, 600 parts of concrete recycled fine powder, 400 parts of cement and 320 parts of water by mass;

[0148] Step 3. Put the solid raw materials into the mixing pot and dry mix at a speed of 2 for 30 s. After that, continue to maintain this mixing speed and slowly add the weighed water within 30 s;

[0149] Step 4. After that, slowly adjust the mixing speed from speed 2 to speed 8 and high-speed mix at this mixing speed for 30 s. After that, stop mixing and clean the mixed materials adhering to the inner wall of the mixing pot within 15 s;

[0150] Step 5. After cleaning, immediately continue to high-speed mix at a mixing speed of 8 for 30 s. After that, clean the mixed materials adhering to the inner wall of the mixing pot;

[0151] Step 6. After cleaning, immediately turn on the pair-roll extrusion granulator with the process parameters set (the process parameters of the pair-roll extrusion granulator are: motor power: 11 KW, granulation size of the driving wheel is 10 mm, rotational speed of the driving wheel is 55 revolutions / min, gap of the driving wheel is 0.3 - 1 mm), and pour the mixed materials in the mixing pot into it for granulation at one time. After granulation, obtain the preformed artificial aggregate in an ellipsoidal shape;

[0152] Step 7. Place the preformed artificial aggregate on an iron tray and place it under natural conditions, cover it with a film and conduct pre-curing for 4 h;

[0153] Step 8. After pre-curing, screen through a 4.75 mm sieve, and then immediately put it into a pressure carbonization kettle, introduce CO2 with a concentration of 99.5%, make the internal gas pressure reach 1 bar, and carbonize for 1 h;

[0154] Step 9. After carbonization curing, immediately conduct water curing, the water temperature is 24 °C, and cure until the specified age to obtain the iron tailings-based negative-carbon artificial aggregate.

[0155] Conduct physical property tests on the obtained finished aggregate according to GB / T 1743.1 - 2010 "Lightweight Aggregates and Their Test Methods". The test results of the artificial aggregate at 28 d are shown in Table 8:

[0156] Table 8 is the physical properties of the aggregate in Example 8

[0157] Single-particle strength (MPa) Apparent density (kg / m3) 24-hour water absorption rate (%) Unit total carbon fixation amount (%) Example 8 3.03 2060.83 13.47 5.00

[0158] It can be seen from this that the results of various embodiments of the present invention show that the single-particle strength of the artificial aggregate produced by the present invention is 0.68 - 3.03 MPa, the unit (net) carbon fixation amount is 4.9 - 7.14%, and the apparent density is 1783 - 2160 kg / m 3 . The unit carbon fixation amount of the artificial aggregate of iron tailings under different examples can all reach 4.95% and above. However, due to the different mass fractions, there are certain differences in the physical and mechanical properties of the artificial aggregate.

[0159] In Example 1 of the present invention, iron tailings powder and cement are used in combination to form a composite aggregate, which has good strength and realizes the effective utilization of iron tailings powder. In Example 2, iron tailings powder, recycled concrete fine powder, and cement are mixed. Although the strength of the aggregate decreases, the water absorption rate and carbon fixation amount both increase. In Example 3, iron tailings powder, steel slag powder, and cement are mixed. Although the strength of the aggregate further decreases, the water absorption rate and carbon fixation amount both further increase. In Example 4, iron tailings powder, calcium carbide powder, and cement are mixed. Although the strength and carbon fixation amount of the aggregate decrease, it has good water absorption rate and can be used in environments that require high water absorption rate. It can be seen from Examples 5, 6, and 7 of the present invention that, while keeping the cement unchanged, reducing the usage amount of iron tailings powder and increasing the recycled concrete fine powder can improve the strength of the aggregate to a certain extent. However, compared with Example 6, the performance of Example 7 has a prominent improvement. Comparing Example 7 with Example 2, it can also be seen that although Example 7 only reduces part of the recycled concrete fine powder, the physical properties of the formed aggregate are significantly improved, far higher than the conventional expectation, indicating that Example 7 provides an efficient solution for the combined use of iron tailings powder and recycled concrete fine powder, and the obtained aggregate has good strength.

[0160] Compared with Example 7, Example 8 of the present invention shortens the carbonization time, but still has good strength, density, and water absorption rate, and the carbon fixation amount still reaches 5%. Moreover, the method of Example 8 can effectively shorten the occupation time of the carbonization kettle. During the large-scale carbonization process, the method of Example 8 can be adopted to effectively improve the production efficiency of the carbonization kettle.

[0161] In summary, the iron tailings-based negative-carbon artificial aggregate of the present invention uses iron tailings powder as the main raw material, and can synergistically add recycled concrete fine powder, steel slag powder, and calcium carbide slag powder. The prepared iron tailings-based negative-carbon artificial aggregate has excellent carbon fixation efficiency and physical and mechanical properties. It greatly improves the resource utilization of iron tailings powder, and at the same time synergistically improves the resource utilization of other solid wastes such as recycled concrete fine powder, calcium carbide slag powder, and steel slag powder, promotes the green transformation of the construction industry, and helps the recycling of solid wastes.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that after reading the specification of this application, they can still modify the specific implementation manners of the present invention or make equivalent substitutions, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention application.

Claims

1. A carbon-negative artificial aggregate based on iron tailings, characterized in that, The negative-carbon artificial aggregate includes the following materials: 16 parts of water, 50 - 90 parts of iron tailings powder, 10 - 30 parts of cement, and 0 - 40 parts of other solid wastes; the other solid wastes include at least one of recycled concrete fine powder, steel slag powder, and carbide slag powder.

2. The iron tailings-based negative-carbon artificial aggregate according to claim 1, characterized in that, The specific surface area of the iron tailings powder is 232.0 m 2 / kg.

3. The iron tailings-based carbon-negative artificial aggregate according to claim 1, characterized in that, The iron tailings powder includes 45% - 55% of SiO2, 15% - 20% of Fe2O3, 10% - 15% of A12O3, and 5% - 10% of CaO.

4. A kind of iron tailings-based negative-carbon artificial aggregate according to claim 1, characterized in that, The specific surface area of the recycled concrete fine powder is 625.7 m 2 / kg.

5. A kind of iron tailings-based negative-carbon artificial aggregate according to claim 1, characterized in that, The particle size of the steel slag powder is less than 150um, and the particle size of the carbide slag powder is less than 150um.

6. The iron tailings-based negative-carbon artificial aggregate according to claim 4, characterized in that, The density of the steel slag powder is 3.18 g / cm 3 .

7. The iron tailings-based carbon-negative artificial aggregate according to claim 4, characterized in that, The CaO content in the carbide slag powder is not less than 70%.

8. The preparation method of the iron tailings-based carbon-negative artificial aggregate according to any one of claims 1-7, characterized in that, The preparation method includes: S1. Mix all the solid raw materials of the iron tailings-based negative-carbon artificial aggregate, stir, and add water. S2. Increase the stirring speed and maintain stirring under high-speed conditions. S3. Granulate and cure to obtain the iron tailings-based negative-carbon artificial aggregate.

9. The preparation method of the iron tailings-based carbon-negative artificial aggregate according to claim 8, characterized in that, The S1 includes: S101. Put the solid raw materials into the mixing pot and dry stir for 30s. S102. Continue to maintain this stirring speed and slowly add the weighed water within 30s.

10. The preparation method of the iron tailings-based carbon-negative artificial aggregate according to claim 8, characterized in that, The S3 includes: S301. Turn on the pair-roller extrusion granulator with the process parameters set, and pour the mixed materials in the mixing pot at one time for granulation. After granulation, an ellipsoidal preform of the artificial aggregate is obtained. S302. Place the preformed artificial aggregate on an iron tray and place it under natural conditions, and cover it with a film for pre-curing for 2 - 6h. S303. After the pre-curing is completed, sieve through a 4.75mm sieve, and then immediately put it into a pressure carbonization kettle, and introduce CO2 with a concentration of 90% - 99.9% to make the internal gas pressure reach 0.5 - 2 bar, and carbonize for 3 - 10h. S304. After the carbonization curing is completed, immediately carry out water curing. The water temperature is 10 - 30°C, and cure for 3 - 28 days to obtain the iron tailings-based negative-carbon artificial aggregate.