阅读说明：本技术 一种高表面活性的轻质骨料及其制备方法 (High-surface-activity light aggregate and preparation method thereof ) 是由 韩辉 陈昌华 王秀龙 林敏燕 高伟强 孙怀涛 高为民 于 2021-09-03 设计创作，主要内容包括：本发明属于人造轻集料技术领域,特别涉及一种高表面活性的轻质骨料及其制备方法。该轻质骨料的原料包括55-82wt％的滇池外海底泥、15-40wt％的滇池草海底泥、3-5wt％的膨润土、3-5wt％的硅灰。轻质骨料的制备方法包括以下步骤,将滇池外海底泥进行脱砂处理；将脱砂后的外海底泥和草海底泥烘干；将烘干后的外海底泥和草海底泥分别利用球磨机粉磨；将滇池外海底泥、滇池草海底泥、膨润土按比例混合配料后加水搅拌；用造粒机造粒；将挤出的生料颗粒放入整形机外裹硅灰烘干；把烘干的生料球送入回转窑煅烧从而得到轻质骨料成品。不仅为滇池底泥大批量综合利用开辟了的新途径,还获得一种高表面活性的轻质骨料。(The invention belongs to the technical field of artificial lightweight aggregates, and particularly relates to a lightweight aggregate with high surface activity and a preparation method thereof. The raw materials of the lightweight aggregate comprise 55-82 wt% of Yunnan pond open sea bottom mud, 15-40 wt% of Yunnan pond grass sea bottom mud, 3-5 wt% of bentonite and 3-5 wt% of silica fume. The preparation method of the lightweight aggregate comprises the following steps of carrying out desanding treatment on the seabed sludge outside the Dian pond; drying the desanded outer seabed mud and grass seabed mud; respectively grinding the dried outer seabed mud and the grass seabed mud by using a ball mill; mixing and batching the Yunnan pond open sea bottom mud, the Yunnan pond grass sea bottom mud and the bentonite according to a proportion, and adding water for stirring; granulating by a granulator; putting the extruded raw material particles into a shaping machine to be wrapped with silica fume and drying; and feeding the dried raw material balls into a rotary kiln for calcination to obtain a finished product of the lightweight aggregate. Not only opens up a new way for the large-scale comprehensive utilization of the bottom mud of the Dian lake, but also obtains a light aggregate with high surface activity.)

1. A high surface active lightweight aggregate characterized by: the lightweight aggregate is prepared from four raw materials, namely Yunnan pond open seabed mud, Yunnan pond grass seabed mud, bentonite and silica fume, and the weight percentage of each raw material is as follows: 55-82 wt% of Yunnan pond open sea bottom mud, 15-40 wt% of Yunnan pond grass sea bottom mud, 3-5 wt% of bentonite and 3-5 wt% of silica fume.

2. The high surface-active lightweight aggregate according to claim 1, wherein: calculated by mass ratio, the loss on ignition of the Dian Po external seabed mud is 8.1-15.0%, and the chemical components comprise 56.0-65.0% of SiO2, 12.0-16.0% of Al2O3, 6.6-9.8% of Fe2O3, 2.0-4.3% of CaO, 1.0-3.0% of MgO, 1.0-3.5% of K2O, 1.0-2.5% of Na2O and 0.42-0.50% of Cr.

3. The high surface-active lightweight aggregate according to claim 1, wherein: calculated by mass ratio, the loss on ignition of the Yunnan grass seabed mud is 24.1-24.6%, and the chemical components comprise 41.4-42.1% of SiO2, 13.2-13.9% of Al2O3, 5.0-7.2% of Fe2O3, 4.6-5.1% of CaO, 2.5-3.2% of MgO, 2.1-2.7% of K2O, 0.2-0.4% of Na2O and 0.23-0.32% of Cr.

4. The high surface-active lightweight aggregate according to claim 1, wherein: calculated by mass ratio, the loss on ignition of the silica fume is 2.0-3.8%, and the chemical components comprise 85.0-92.0% of SiO2, 0.9-1.2% of Al2O3, 0.7-0.9% of Fe2O3, 0.3-0.5% of CaO, 0.7-1.2% of MgO, 0.3-0.6% of K2O, and 0.5-0.9% of Na 2O.

5. The high surface-active lightweight aggregate according to claim 1, wherein: the specific surface area of the silica fume is 80-88 m2/g, and the activity index of the silica fume is not less than 110%.

6. The high surface-active lightweight aggregate according to claim 1, wherein: the lightweight aggregate has a water absorption of 2.5-8.0%, a barrel pressure of 3.5-9.8MPa, and a bulk density of 280-882kg/m³。

7. The method for preparing a lightweight aggregate with high surface activity according to claim 1, wherein: the method comprises the following steps of,

s1, carrying out desanding treatment on the open sea bottom mud of the Dian-Yuan pond by adopting a 100-mesh sieve until the sand content is less than or equal to 5 wt%;

s2, drying the desanded open sea sediment and grass sea sediment in an oven at the temperature of 105 ℃;

s3, respectively grinding the dried outer seabed mud and the dried grass seabed mud by using a ball mill until the residue of the sieve with the particle size of 80 mu m is less than or equal to 20%;

s4, mixing 55-82 wt% of Yunnan pond extra-sea bottom mud, 15-40 wt% of Yunnan pond grass extra-sea bottom mud and 3-5 wt% of bentonite according to a proportion, adding a proper amount of water, and uniformly stirring by a high-speed stirrer;

s5, preparing cylindrical raw material particles with the diameter of 8-15mm and the water content less than or equal to 20% by using an extrusion granulator;

s6, putting the extruded raw material particles into a shaping machine, simultaneously putting 3-5 wt% of silica fume to coat the surfaces of the raw material particles, and putting the raw material particles into an oven to dry after the coating is finished;

s7, conveying the dried raw material balls into a rotary kiln heated to 500 ℃, heating the raw material balls from 500 ℃ to 1050-; finally, the temperature is quickly raised to 1150-1200 ℃ for calcining for 8-15min, and the rotating speed of the rotary kiln is controlled at 1-2 r/min; the sintered aggregate is taken out from the kiln head and naturally cooled to normal temperature in the air, thereby obtaining the finished product of the lightweight aggregate.

Technical Field

The invention belongs to the technical field of artificial lightweight aggregates, and particularly relates to a lightweight aggregate with high surface activity and a preparation method thereof.

Background

The aggregate is commonly known as artificial lightweight aggregate; the aggregate is widely applied to the fields of building materials, gardening, sewage treatment, fire-resistant heat-insulating materials, chemical engineering, petroleum and the like because of the multifunctional characteristics of light weight, corrosion resistance, frost resistance, earthquake resistance, good isolation and the like;

at present, the preparation raw materials of the aggregate are mainly clay or shale, and as the clay is a precious natural resource, the vigorous development of the clay aggregate can lead to the destruction and loss of a large amount of high-quality cultivated land; the production of the aggregate by using the shale damages natural vegetation and environment and breaks the balance of an ecosystem to a certain extent, and the preparation of the lightweight aggregate by using the solid waste raw material is important content of sustainable development of the future countries.

Chinese patent (application No. 201811639296.6) discloses a method for preparing ceramsite mainly by using 50-70% of sludge, 10-25% of steel slag, 10-30% of correcting agent and 1-10% of foaming agent, wherein the ceramsite has the bulk density of 450Kg/m3, the water absorption rate of 11.34% and the cylinder pressure strength of 2.5 MPa. Chinese patent (application No. 201711403528.3) discloses a method for preparing sintered ceramsite by using river bottom silt, yellow river silt and fly ash as main raw materials, wherein the bulk density is 600-700 kg/m3, the cylinder pressure strength is 4.1-4.5 MPa, and the water absorption rate after 1 hour of water immersion is 6.8-7.2%. The silt of the Nanjing Jiulong lake area is used for preparing 1005-dose sand 1291kg/m³The sludge ceramsite has the following problems: the barrel pressure strength of the sludge ceramsite prepared by the prior art is lower than the standard requirement; the water absorption of the sludge ceramsite can not meet the standard requirement of high-strength ceramsite; sludgeThe stacking density of the ceramsite is too high, so that the lightweight high-strength ceramsite cannot be obtained; the reaction activity between the surface of the sludge ceramsite and the cementing material is poor.

The Dian-Chi dredging engineering mainly includes dredging open sea and grass sea, and the dredging obtained bottom mud mainly contains fine granular soil, is rich in organic matter and various pollutants, and is usually scattered to form a high-water-content mud state due to the disturbance of dredging construction, and essentially belongs to high-water-content solid waste. By 2013, the yunnan pond has been subjected to three-phase dredging engineering in total, and from 1998 to three-phase dredging engineering shuttle works, about 1464 million tons of swimming mud have been dredged from the yunnan pond and peripheral rivers for the dredging engineering of over one decade, but the swimming mud accounts for about 1/10 of the predicted total amount of the swimming mud in the lake region, and 8000 million tons to 1.2 million tons of swimming mud are predicted to wait for dredging. The problem that the treatment of the bottom mud generated by the dredging of the Dian-Chi is unavoidable at present is that the smooth comprehensive treatment of the Dian-Chi pollution is hindered if the total amount of the bottom mud of the Dian-Chi is too large and a terminal treatment mode of reduction, harmlessness (containing heavy metal elements Cr), resource utilization, large scale and no occupation or little occupation of land resources is not adopted for the bottom mud of the Dian-Chi. Therefore, the invention solves the problems that the open sea bottom mud and the grass sea bottom mud generated by the yunnan pond dredging engineering are taken as main raw materials to prepare the lightweight aggregate, the yunnan pond bottom mud is thoroughly and harmlessly treated, and meanwhile, the economic and environmental protection benefits are realized.

Disclosure of Invention

The invention aims to solve the problems in the prior art, provides a light aggregate with good surface activity prepared by using the bottom mud and the grass sea mud generated by dredging the yunnan pond as main raw materials, opens up a new way for the large-scale comprehensive utilization of the yunnan pond bottom mud, changes the waste of the bottom mud into valuable, practically achieves the aims of recycling, reducing and harmless treatment, and has important practical significance.

The technical solution for achieving the above object of the present invention can be summarized as follows:

the invention aims to provide a high-surface-activity lightweight aggregate, which is prepared from the raw materials of Yunnan pond open sea bottom mud, Yunnan pond grass sea bottom mud, bentonite and the like in percentage by mass: 55-82 wt% of Yunnan pond open sea bottom mud, 15-40 wt% of Yunnan pond grass sea bottom mud, 3-5 wt% of bentonite and 3-5 wt% of silica fume.

Further, the loss on ignition of the Yunnan pond external seabed mud is 8.1-15.0%, the chemical components comprise 56.0-65.0% of SiO2, 12.0-16.0% of Al2O3, 6.6-9.8% of Fe2O3, 2.0-4.3% of CaO, 1.0-3.0% of MgO, 1.0-3.5% of K2O, 1.0-2.5% of Na2O and 0.42-0.50% of Cr in percentage by mass.

Further, the loss on ignition of the Yunnan grass seabed mud is 24.1-24.6% calculated by mass ratio, and the chemical components comprise 41.4-42.1% of SiO2, 13.2-13.9% of Al2O3, 5.0-7.2% of Fe2O3, 4.6-5.1% of CaO, 2.5-3.2% of MgO, 2.1-2.7% of K2O, 0.2-0.4% of Na2O and 0.23-0.32% of Cr.

Furthermore, the loss on ignition of the silica fume is 2.0-3.8% calculated by mass ratio, and the chemical components comprise 85.0-92.0% of SiO2, 0.9-1.2% of Al2O3, 0.7-0.9% of Fe2O3, 0.3-0.5% of CaO, 0.7-1.2% of MgO, 0.3-0.6% of K2O and 0.5-0.9% of Na 2O.

Furthermore, the specific surface area of the silica fume is 80-88 m2/g, and the activity index of the silica fume is not less than 110%.

Further, the lightweight aggregate has a water absorption of 2.5-8.0%, a barrel pressure strength of 3.5-9.8MPa, and a bulk density of 280-882kg/m³。

It is another object of the present invention to provide a method for preparing the above high surface active lightweight aggregate, which comprises the steps of,

s1, carrying out desanding treatment on the open sea bottom mud of the Dian-Yuan pond by adopting a 100-mesh sieve until the sand content is less than or equal to 5 wt%;

s2, drying the desanded open sea sediment and grass sea sediment in an oven at the temperature of 105 ℃;

s3, respectively grinding the dried outer seabed mud and the dried grass seabed mud by using a ball mill until the residue of the sieve with the particle size of 80 mu m is less than or equal to 20%;

s4, mixing 55-82 wt% of Yunnan pond extra-sea bottom mud, 15-40 wt% of Yunnan pond grass extra-sea bottom mud and 3-5 wt% of bentonite according to a proportion, adding a proper amount of water, and uniformly stirring by a high-speed stirrer;

s5, preparing cylindrical raw material particles with the diameter of 8-15mm and the water content less than or equal to 20% by using an extrusion granulator;

s6, putting the extruded raw material particles into a shaping machine, simultaneously putting 3-5 wt% of silica fume to coat the surfaces of the raw material particles, and putting the raw material particles into an oven to dry after the coating is finished;

s7, conveying the dried raw material balls into a rotary kiln heated to 500 ℃, heating the raw material balls from 500 ℃ to 1050-; finally, the temperature is quickly raised to 1150-1200 ℃ for calcining for 8-15min, and the rotating speed of the rotary kiln is controlled at 1-2 r/min; the sintered aggregate is taken out from the kiln head and naturally cooled to normal temperature in the air, thereby obtaining the finished product of the lightweight aggregate.

The invention has the advantages and positive effects that:

(1) firstly, the problem that the light aggregate cannot be prepared by using the grass sea bottom mud alone due to high organic matter content is solved, and the internal pore structure of the aggregate can be improved by fully utilizing more organic carbon in the grass sea bottom mud;

(2) secondly, the problem that the open sea bottom mud has less organic matters and can not be independently prepared into a lower density grade (less than or equal to 800 kg/m)³) The lightweight aggregate of (a);

(3) the surface of the lightweight aggregate is coated by silica fume, so that the chemical reaction activity between the lightweight aggregate and cementing materials such as cement is improved; (4) the invention adopts the Dian-Chi dredging engineering to produce the grass-sea bottom mud and the open sea bottom mud as the main raw materials to prepare the lightweight aggregate, thereby realizing the environmental protection idea of using waste to prepare waste, reducing the influence of solid waste stockpiling on the environment, and the prepared lightweight aggregate can be applied to lightweight structural concrete, heat-insulating plates, prefabricated components and fabricated buildings;

(5) by high-temperature calcination, a ferrochrome solid solution (Fe) is formed inside the lightweight aggregate_0.6Cr_0.4)2O₃) The solid solution uses Cr as heavy metal element³⁺The valence bond form is dissolved in the internal structure of the lightweight aggregate, so that the risk that the heavy metal trivalent chromium is dissolved out when meeting acid and alkali and is easily oxidized into the toxic six-valence bond Cr6+ is reduced.

In conclusion, the invention has positive significance for environmental protection.

Drawings

FIG. 1 is an XRD diffraction analysis of a lightweight aggregate prepared by the process of the present invention.

Detailed Description

Aiming at the problems of the aggregate in the prior art, the invention discloses a light aggregate with high surface activity, which is prepared from the raw materials of Yunnan pond open sea bottom mud, Yunnan pond grass sea bottom mud, bentonite and the like, wherein the chemical compositions of the raw materials are shown in Table 1; the mass percentage of each raw material is as follows: 55-82 wt% of Yunnan pond open sea bottom mud, 15-40 wt% of Yunnan pond grass open sea bottom mud, 3-5 wt% of bentonite and 3-5 wt% of silica fume (externally doped).

As raw materials, the main chemical components of the yunnan pond external seabed mud, the yunnan pond grass seabed mud and the silica fume need to meet the requirements in table 1:

TABLE 1 Main chemical composition (wt%) of Dian Po open seabed mud and Dian Po seabed mud

The silicon ash is also called micro silicon powder or condensed silicon ash, and is formed by that when ferroalloy is used for smelting ferrosilicon and industrial silicon, a large amount of SiO2 and Si gas with strong volatility is generated in an ore-smelting electric furnace, and the gas is quickly oxidized, condensed and precipitated with air after being discharged. It is a by-product in large-scale industrial smelting. The silica fume used in the invention is obtained by processing the silica fume by ultrafine grinding equipment, the ultrafine grinding can uniformly disperse the spherical particles which are aggregated together by amorphous phase in the silica fume, and the specific surface area is 23-28 m from the initial²The/g becomes 80 to 88m²The surface free energy of the silica fume is increased, the activity index of the silica fume is more than or equal to 110 percent, and the silica fume belongs to a volcanic ash material with high activity.

The invention discloses a preparation method of the lightweight aggregate, which comprises the following steps:

s1, carrying out desanding treatment on the open sea bottom mud of the Dian-Yuan pond by adopting a 100-mesh sieve until the sand content is less than or equal to 5 wt%;

s2, drying the desanded open sea sediment and grass sea sediment in an oven at the temperature of 105 ℃;

s3, respectively grinding the dried outer seabed mud and the dried grass seabed mud by using a ball mill until the residue of the sieve with the particle size of 80 mu m is less than or equal to 20%;

s4, mixing 55-82 wt% of Yunnan pond extra-sea bottom mud, 15-40 wt% of Yunnan pond grass extra-sea bottom mud and 3-5 wt% of bentonite according to a proportion, adding a proper amount of water, and uniformly stirring by a high-speed stirrer;

s5, preparing cylindrical raw material particles with the diameter of 8-15mm and the water content less than or equal to 20% by using an extrusion granulator;

s6, putting the extruded raw material particles into a shaping machine, simultaneously putting 3-5 wt% of silica fume to coat the surfaces of the raw material particles, and putting the raw material particles into an oven to dry after the coating is finished;

s7, conveying the dried raw material balls into a rotary kiln (phi 0.4m x 0.6m) heated to 500 ℃, heating the raw material balls to 1050-; finally, the temperature is quickly raised to 1150-1200 ℃ for calcining for 8-15min, and the rotating speed of the rotary kiln is controlled at 1-2 r/min; the sintered aggregate is taken out from the kiln head and naturally cooled to normal temperature in the air, thereby obtaining 882kg/m of water absorption rate of 2.5-8.0%, cylinder pressure strength of 3.5-9.8MPa and bulk density of 280-³The finished product of the lightweight aggregate.

In order to further understand the contents, features and effects of the present invention, the following examples are listed:

example 1

A high surface active lightweight aggregate, the method comprising the steps of:

s1, carrying out desanding treatment on the open sea bottom mud of the Dian-Yuan pond by adopting a 100-mesh sieve until the sand content is less than or equal to 5 wt%;

s2, drying the desanded open sea sediment and grass sea sediment in an oven at the temperature of 105 ℃;

s3, respectively grinding the dried outer seabed mud and the dried grass seabed mud by using a ball mill until the residue of the sieve with the particle size of 80 mu m is less than or equal to 20%;

s4, mixing and blending 55 wt% of outer seabed mud powder, 40 wt% of grass seabed mud powder and 5 wt% of bentonite, adding a proper amount of water, and uniformly stirring by a high-speed stirrer;

s5, preparing cylindrical raw material particles with the diameter of 8-15mm and the water content less than or equal to 20% by using an extrusion granulator;

s6, putting the extruded raw material particles into a shaping machine, simultaneously putting 5 wt% of silica fume to coat the surfaces of the raw material particles, and putting the raw material particles into an oven to dry after the coating is finished;

s7, conveying the dried raw material balls into a rotary kiln (phi 0.4m x 0.6m) heated to 500 ℃, heating the raw material balls to 1050 ℃ from 500 ℃, and controlling the rotating speed of the rotary kiln at 1r/min for 35 min; finally, quickly heating to 1180 ℃ and calcining for 8 min; the rotating speed of the rotary kiln is controlled at 1.5 r/min; as shown in FIG. 1, a solid solution of iron and chromium (Fe) is formed inside the lightweight aggregate by high-temperature calcination_0.6Cr_0.4)2O₃) The solid solution uses Cr as heavy metal element³⁺The valence bond form is dissolved in the internal structure of the lightweight aggregate, so that the risk that the heavy metal trivalent chromium is dissolved out when meeting acid and alkali and is easily oxidized into the toxic six-valence bond Cr6+ is reduced. The sintered aggregate is taken out from the kiln head and naturally cooled to normal temperature in the air, thereby obtaining the finished product of the lightweight aggregate. The aggregate product obtained in the scheme is characterized in that: bulk density of 280kg/m³The cylinder pressure strength is 3.5MPa, and the water absorption rate is 8.0 percent in 1 hour.

Example 2

A high surface active lightweight aggregate, the method comprising the steps of:

s1, carrying out desanding treatment on the open sea bottom mud of the Dian-Yuan pond by adopting a 100-mesh sieve until the sand content is less than or equal to 5 wt%;

s2, drying the desanded open sea sediment and grass sea sediment in an oven at the temperature of 105 ℃;

s3, respectively grinding the dried outer seabed mud and the dried grass seabed mud by using a ball mill until the residue of the sieve with the particle size of 80 mu m is less than or equal to 20%;

s4, mixing and blending 82 wt% of outer seabed mud powder, 15 wt% of grass seabed mud powder and 3 wt% of bentonite, adding a proper amount of water, and uniformly stirring by a high-speed stirrer;

s5, preparing cylindrical raw material particles with the diameter of 8-15mm and the water content less than or equal to 20% by using an extrusion granulator;

s6, putting the extruded raw material particles into a shaping machine, simultaneously putting 3% of silica fume to coat the surfaces of the raw material particles, and putting the raw material particles into an oven to dry after the coating is finished;

s7, conveying the dried raw material balls into a rotary kiln (phi 0.4m x 0.6m) heated to 500 ℃, heating to 1080 ℃ from 500 ℃, wherein the heating time is 25min, and the rotating speed of the rotary kiln is controlled at 2 r/min; finally, quickly heating to 1200 ℃ for calcining for 15min, and controlling the rotating speed of the rotary kiln at 1.5 r/min; the sintered aggregate is taken out from the kiln head and naturally cooled to normal temperature in the air, thereby obtaining the finished product of the lightweight aggregate. The aggregate product obtained in the scheme is characterized in that: bulk density of 882kg/m³The cylinder pressure strength is 9.8MPa, and the water absorption rate is 2.5% in 1 h.

Example 3

A high surface active lightweight aggregate, the method comprising the steps of:

s1, carrying out desanding treatment on the open sea bottom mud of the Dian-Yuan pond by adopting a 100-mesh sieve until the sand content is less than or equal to 5 wt%;

s2, drying the desanded open sea sediment and grass sea sediment in an oven at the temperature of 105 ℃;

s3, respectively grinding the dried outer seabed mud and the dried grass seabed mud by using a ball mill until the residue of the sieve with the particle size of 80 mu m is less than or equal to 20%;

s4, mixing and blending 70 wt% of outer seabed mud powder, 26 wt% of grass seabed mud powder and 4 wt% of bentonite according to the mass percentage, adding a proper amount of water, and uniformly stirring by a high-speed stirrer;

s5, preparing cylindrical raw material particles with the diameter of 8-15mm and the water content less than or equal to 20% by using an extrusion granulator;

s6, putting the extruded raw material particles into a shaping machine, simultaneously putting 4 wt% of silica fume to coat the surfaces of the raw material particles, and putting the raw material particles into an oven to dry after the coating is finished;

s7, conveying the dried raw material balls into a rotary kiln (phi 0.4m x 0.6m) heated to 500 ℃, heating to 1065 ℃ from 500 ℃, wherein the heating time is 25-35min, and the rotating speed of the rotary kiln is controlled at 1.5 r/min; finally, quickly heating to 1175 ℃ to calcine for 12min, and controlling the rotating speed of the rotary kiln at 1 r/min; the sintered aggregate is taken out from the kiln head and naturally cooled to normal temperature in the air, thereby obtaining the finished product of the lightweight aggregate. The aggregate product obtained in the scheme is characterized in that: the bulk density was 688kg/m3, the barrel pressure strength was 7.5MPa, and the water absorption at 1h was 4.6%.

Example 4

A high surface active lightweight aggregate, the method comprising the steps of:

s1, carrying out desanding treatment on the open sea bottom mud of the Dian pond by adopting a 100-mesh sieve until the sand content is less than or equal to 5 percent;

s2, drying the desanded open sea sediment and grass sea sediment in an oven at the temperature of 105 ℃;

s3, respectively grinding the dried outer seabed mud and the dried grass seabed mud by using a ball mill until the residue of the sieve with the particle size of 80 mu m is less than or equal to 20%;

s4, mixing and blending 66 wt% of outer seabed mud powder, 30 wt% of grass seabed mud powder and 4 wt% of bentonite, adding a proper amount of water, and uniformly stirring by a high-speed stirrer;

s5, preparing cylindrical raw material particles with the diameter of 8-15mm and the water content less than or equal to 20% by using an extrusion granulator;

s6, putting the extruded raw material particles into a shaping machine, simultaneously putting 4.5 wt% of silica fume to coat the surfaces of the raw material particles, and putting the raw material particles into an oven to dry after the coating is finished;

s7, conveying the dried raw material balls into a rotary kiln (phi 0.4m x 0.6m) heated to 500 ℃, heating to 1080 ℃ from 500 ℃, wherein the heating time is 25-35min, and the rotating speed of the rotary kiln is controlled at 1.5 r/min; finally, quickly heating to 1150 ℃ for calcining for 10min, and controlling the rotating speed of the rotary kiln at 2 r/min; the sintered aggregate is taken out from the kiln head and naturally cooled to normal temperature in the air, thereby obtaining the finished product of the lightweight aggregate. The aggregate product obtained in the scheme is characterized in that: the bulk density was 520kg/m3, the barrel pressure was 5.5MPa, and the water absorption at 1 hour was 6.8%.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications, equivalent changes and modifications made to the above embodiment according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.