Artificial light aggregate with multi-stage gradient structure and preparation method thereof

Abstract

The application discloses a kind of artificial light aggregate with multistage gradient structure, belong to artificial light aggregate technical field.The artificial light aggregate of the application includes from inside to outside distribution core, light transition layer, sub-light transition layer and shell;The raw material of core includes multi-source solid waste material and rapid foaming agent;The raw material of light transition layer includes multi-source solid waste material, rapid foaming agent and slow-release pore-forming agent;The raw material of sub-light transition layer includes multi-source solid waste material and slow-release pore-forming agent;The raw material of shell includes multi-source solid waste material and additive.The artificial light aggregate of the application, its bulk density and 1h water absorption are lower, cylinder pressure strength and specific strength are higher, have good application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of artificial light aggregate, and particularly relates to an artificial light aggregate with a multi-level gradient structure and a preparation method thereof. BACKGROUND

[0002] With the continuous development of China's steel industry, China has become one of the countries with the largest increase and storage of iron tailings and metallurgical slag in the world. For a long time, these industrial solid wastes in China have been mainly treated by stacking and filling. This approach not only consumes a lot of resources such as manpower, financial resources and material resources, but also has a negative impact on the ecological environment. How to reasonably dispose and utilize industrial solid wastes has become a big problem today.

[0003] At present, natural aggregate resources are scarce, and the development of artificial aggregate has good use value for saving natural resources of human beings and reducing cost. However, the current artificial aggregate is mainly concentrated in two aspects of ceramic particle sintering and cement-based non-burning material. As we all know, ceramic particle sintering consumes a large amount of energy materials, and the controllability of its performance is low, and the performance is poor, so that the actual application is greatly limited. For cement-based artificial aggregate, due to the cost and carbon emission in the cement production process, the mixing amount of cement in artificial light aggregate should not be too high, which also limits the development of its performance. The development of new building materials by using industrial solid waste materials not only can reduce environmental pollution, save natural resources and improve the resource utilization level of solid waste, but also is beneficial to save energy consumption and reduce CO2 emission, and helps to achieve the double carbon goal. Therefore, it is of great significance to coordinate the application of bulk industrial solid waste materials to prepare an artificial light aggregate with a multi-level gradient structure. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides an artificial light aggregate with a multi-level gradient structure and a preparation method thereof, which can improve the utilization rate of solid waste materials, is beneficial to reduce environmental pollution and save natural resources. The following technical solutions are used.

[0005] The artificial light aggregate with a multi-level gradient structure provided by the present application comprises a core, a light transition layer, a sub-light transition layer and a shell which are sequentially distributed from inside to outside;

[0006] The core has a large pore, and the raw material comprises multi-source solid waste materials and a rapid foaming agent with a mass ratio of (9-49):1;

[0007] The light transition layer has a micropore, and the raw material comprises multi-source solid waste materials, a rapid foaming agent and a slow-release pore-forming agent with a mass ratio of (300-800):(10-24):1;

[0008] The sub-lightweight transition layer has fine pores, and the raw materials include multi-source solid waste materials and slow-release pore-forming agents in a mass ratio of (99-499):1;

[0009] The shell is dense, and the raw materials include multi-source solid waste materials and external agents in a mass ratio of (49-199):1.

[0010] Preferably, the mass ratio of the multi-source solid waste materials in the core, the lightweight transition layer, the sub-lightweight transition layer and the shell is (3-5):(3-5):2:1.

[0011] Preferably, the multi-source solid waste materials include at least one of iron tailings, steel slag, desulfurization gypsum and slag.

[0012] Further preferably, the multi-source solid waste materials include iron tailings, steel slag, desulfurization gypsum and slag in a mass ratio of (4.5-12):(1-3):1:(1.5-5).

[0013] Further preferably, the iron tailings are high-silicon iron tailings powder with a SiO2 content greater than 70%.

[0014] Further preferably, the steel slag is steel slag fine powder with a specific surface area greater than 360m 2 / kg.

[0015] Further preferably, the desulfurization gypsum is finely ground desulfurization gypsum powder with a CaSO4·2H2O content greater than 95%.

[0016] Further preferably, the slag is blast furnace slag powder of S95 and / or S105 grade.

[0017] Preferably, the rapid foaming agent includes at least one of sodium percarbonate and hydrogen peroxide.

[0018] Preferably, the slow-release pore-forming agent includes at least one of sodium abietate, ammonium bicarbonate, calcium lignosulfonate and ammonium nitrate.

[0019] Preferably, the external agent includes at least one of naphthalene-based water reducing agent, polycarboxylic acid water reducing agent and calcium lignosulfonate.

[0020] The present application provides a preparation method of a multi-level gradient structure artificial lightweight aggregate, comprising the following steps:

[0021] Mixing the multi-source solid waste materials and the rapid foaming agent in a mass ratio to obtain a core mixture; mixing the multi-source solid waste materials with the rapid foaming agent and the slow-release pore-forming agent in a mass ratio to obtain a lightweight transition layer mixture; and mixing the multi-source solid waste materials with the slow-release pore-forming agent in a mass ratio to obtain a sub-lightweight transition layer mixture;

[0022] A small amount of core mixture is taken as a base material to form a sandy state, and then the remaining core mixture is granulated while continuously spraying water to obtain a first aggregate body with a core;

[0023] The light transition layer mixture is added to the first aggregate body to granulate while continuously spraying water to obtain a second aggregate body with a light transition layer;

[0024] The sub-light transition layer mixture is added to the second aggregate body to granulate while continuously spraying water to obtain a third aggregate body with a sub-light transition layer;

[0025] The multi-source solid waste material is added to the third aggregate body in a proportion while continuously spraying water with dissolved additives to obtain a man-made light aggregate body with a shell;

[0026] The man-made light aggregate body is placed and autoclaved for curing and cooling to obtain a man-made light aggregate.

[0027] Preferably, in the first aggregate body, the mass ratio of water to multi-source solid waste material is (0.2-0.3):1; in the light transition layer of the second aggregate body, the sub-light transition layer of the third aggregate body, and the shell of the man-made light aggregate body, the mass ratio of water to multi-source solid waste material is (0.1-0.2):1.

[0028] Preferably, the standing time is 3-5h.

[0029] Preferably, the autoclaving curing condition is a pressure of 0.8-1.4MPa for 6-12h.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] 1. The bulk density of the man-made light aggregate can be as low as 620kg / m 3 , the 1h water absorption can be as low as 2.2%, the cylinder compressive strength can reach 7.1MPa, and the specific strength can reach 10.47MPa. Compared with the iron tailings cement-based and iron tailings slag-based sinter-free light aggregate, the bulk density and 1h water absorption of the man-made light aggregate of the present application are significantly reduced, and the cylinder compressive strength and specific strength are significantly improved. Therefore, the man-made light aggregate of the present application has good use value;

[0032] 2. The man-made light aggregate of the present application is based on solid waste materials such as iron tailings, steel slag, desulfurization gypsum and slag, combined with a rapid foaming agent, a slow-release pore-forming agent and an additive, to prepare a man-made light aggregate with high performance, which reasonably utilizes bulk industrial solid waste materials, not only improves the utilization rate of solid waste materials, but also saves natural resources and energy consumption, and reduces environmental pollution;

[0033] 3、The preparation method of the artificial light aggregate of the present application, which ingeniously combines the use of a rapid foaming agent, a slow-release pore-forming agent and an additive, to prepare an artificial light aggregate with a multi-level gradient structure, and combines a steam curing process, so that the artificial light aggregate of the present application has the excellent properties of high strength, light weight and low production cost, and can be used as a new type of building material; and also provides a new technical solution for the resource utilization of solid waste materials in the metallurgical industry and the development of natural aggregate replacement products. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The figure is a schematic diagram of the gradient structure of the artificial light aggregate of the present application. DETAILED DESCRIPTION

[0035] In order to further illustrate the present application, the technical solutions provided by the present application are described in detail below in conjunction with examples, but they should not be understood as limiting the protection scope of the present application.

[0036] The present application provides an artificial light aggregate with a multi-level gradient structure, which comprises a core, a light transitional layer, a sub-light transitional layer and a shell distributed in turn from inside to outside.

[0037] The core has large pores, and the raw materials include multi-source solid waste materials and a rapid foaming agent with a mass ratio of (9-49):1; a large number of experiments conducted by the applicant have confirmed that the multi-source solid waste materials and the rapid foaming agent can be used to prepare the artificial light aggregate of the present application within the above range, and only some examples are given below.

[0038] The light transitional layer has micropores, and the raw materials include multi-source solid waste materials, a rapid foaming agent and a slow-release pore-forming agent with a mass ratio of (300-800):(10-24):1; a large number of experiments conducted by the applicant have confirmed that the multi-source solid waste materials, the rapid foaming agent and the slow-release pore-forming agent can be used to prepare the artificial light aggregate of the present application within the above range, and only some examples are given below.

[0039] The sub-light transitional layer has fine micropores, and the raw materials include multi-source solid waste materials and a slow-release pore-forming agent with a mass ratio of (99-499):1; a large number of experiments conducted by the applicant have confirmed that the multi-source solid waste materials and the slow-release pore-forming agent can be used to prepare the artificial light aggregate of the present application within the above range, and only some examples are given below.

[0040] The shell is dense, and the raw materials include multi-source solid waste materials and an additive with a mass ratio of (49-199):1. A large number of experiments conducted by the applicant have confirmed that the multi-source solid waste materials and the additive can be used to prepare the artificial light aggregate of the present application within the above range, and only some examples are given below.

[0041] Optionally, the multi-source solid waste materials include at least one of iron tailings, steel slag, desulfurization gypsum and slag.

[0042] Further optionally, the multi-source solid waste material comprises iron tailings, steel slag, desulfurization gypsum and slag in a mass ratio of (4.5-12):(1-3):1:(1.5-5). A large number of experiments conducted by the applicant have confirmed that the mass ratio of iron tailings, steel slag, desulfurization gypsum and slag within the above range can all prepare the artificial lightweight aggregate of the present application, and only some examples are given below.

[0043] Further optionally, the iron tailings are high-silicon iron tailings powder with a SiO2 content greater than 70%.

[0044] Further optionally, the steel slag is steel slag fine powder with a specific surface area greater than 360 m 2 / kg.

[0045] Further optionally, the desulfurization gypsum is finely ground desulfurization gypsum powder with a CaSO4·2H2O content greater than 95%.

[0046] Further optionally, the slag is blast furnace slag powder of S95 and / or S105 grade.

[0047] Optionally, the rapid foaming agent comprises at least one of sodium percarbonate and hydrogen peroxide.

[0048] Optionally, the slow-release pore-forming agent comprises at least one of sodium abietate, ammonium bicarbonate, calcium lignosulfonate and ammonium nitrate.

[0049] Optionally, the admixture comprises at least one of naphthalene-based water reducing agent, polycarboxylic acid water reducing agent and calcium lignosulfonate.

[0050] The present application provides a preparation method of an artificial lightweight aggregate with a multi-level gradient structure, comprising the following steps:

[0051] Mixing the multi-source solid waste material and the rapid foaming agent in a mass ratio to obtain a core mixture; mixing the multi-source solid waste material with the rapid foaming agent and the slow-release pore-forming agent in a mass ratio to obtain a lightweight transition layer mixture; mixing the multi-source solid waste material with the slow-release pore-forming agent in a mass ratio to obtain a sub-lightweight transition layer mixture;

[0052] Taking a small amount of the core mixture as a base material to form a sand-like shape, and then adding the remaining core mixture to granulate, while continuously spraying water, to obtain a first aggregate blank body with a core;

[0053] Adding the lightweight transition layer mixture to the above-mentioned first aggregate blank body to granulate, while continuously spraying water, to obtain a second aggregate blank body with a lightweight transition layer;

[0054] Adding the sub-lightweight transition layer mixture to the above-mentioned second aggregate blank body to granulate, while continuously spraying water, to obtain a third aggregate blank body with a sub-lightweight transition layer;

[0055] Adding multi-source solid waste materials to the third aggregate blank body in proportion, while continuously spraying water with dissolved additives, to obtain a man-made light aggregate blank body with a shell;

[0056] Letting the man-made light aggregate blank body stand, autoclave curing, and cooling to obtain a man-made light aggregate.

[0057] Optionally, in the first aggregate blank body, the mass ratio of water to multi-source solid waste materials is (0.2-0.3):1; in the light transitional layer of the second aggregate blank body, the sub-light transitional layer of the third aggregate blank body, and the shell of the man-made light aggregate blank body, the mass ratio of water to multi-source solid waste materials is (0.1-0.2):1.

[0058] Optionally, the standing time is 3-5h.

[0059] Optionally, the autoclave curing conditions are: pressure 0.8-1.4MPa, time 6-12h. The applicant has conducted a large number of experiments to prove that the autoclave curing conditions within the above range can all prepare the man-made light aggregate of the present application, and only some examples are given below.

[0060] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0061] In the embodiments and comparative examples of the present application, the sources of the materials used are as follows:

[0062] ① Iron tailings powder: high-silicon iron tailings powder, Benxi Longxin Mining Co., Ltd.;

[0063] ② Steel slag powder: specific surface area 370m 2 / kg or specific surface area 390m 2 / kg, Fushun Xingang Iron and Steel Co., Ltd.;

[0064] ③ Mineral powder: S95 or S105, Fushun Xingang Iron and Steel Co., Ltd.;

[0065] ④ Desulfurization gypsum: Fushun Xingang Iron and Steel Co., Ltd.;

[0066] ⑤ Sodium percarbonate: Zhejiang Jinke Chemical Co., Ltd.;

[0067] ⑥ Sodium abietate: Shandong Wantai Chemical Co., Ltd.;

[0068] ⑦ Ammonium bicarbonate: Shenyang Sainiyou Chemical Co., Ltd.;

[0069] ⑧ Naphthalene-based water reducing agent: Shandong Zhuoan Chemical Co., Ltd.;

[0070] 9. Polycarboxylate superplasticizer: Jiangsu Botex New Material Co., Ltd.

[0071] The chemical compositions of the above-mentioned iron tailings, steel slag and slag are shown in Tables 1-3.

[0072] Table 1 Chemical composition table of iron tailings

[0073] Component TFe FeO Fe2O3 SiO2 Al2O3 CaO Content (%) 10.79 2.75 12.37 72.04 0.76 2.10 Component MgO K2O Na2O P S Ig Content (%) 5.44 0.025 0.033 0.084 0.15 3.68

[0074] Table 2 Chemical composition table of steel slag

[0075]

[0076] Table 3 Chemical composition table of slag

[0077] Chemical composition CaO SiO2 Al2O3 MgO SO3 TiO2 MnO Content (%) 47.66 23.4 11.3 4.86 2.66 1.13 0.36

[0078] Example 1

[0079] The present embodiment provides a kind of artificial light aggregate with multi-level gradient structure, including by inside to outside distribution core, light transition layer, sub-light transition layer and shell;

[0080] The raw material of the core includes 6 kg of multi-source solid waste material and 247 g of sodium percarbonate, and the mass ratio of the multi-source solid waste material and sodium percarbonate is 24.3:1;

[0081] The raw material of the light transition layer includes 8 kg of multi-source solid waste material, 237 g of sodium percarbonate and 10 g of sodium rosin acid, and the mass ratio of the total mass of sodium percarbonate and sodium rosin acid to the mass of multi-source solid waste material is 1:32.4;

[0082] The raw material of the sub-light transition layer includes 4 kg of multi-source solid waste material and 16 g of sodium rosin acid, and the mass ratio of the multi-source solid waste material and sodium rosin acid is 250:1;

[0083] The raw material of the shell includes 2 kg of multi-source solid waste material and 40 g of naphthalene-based superplasticizer, and the mass ratio of the multi-source solid waste material and naphthalene-based superplasticizer is 50:1.

[0084] The preparation method of the artificial light aggregate of the present embodiment includes the following steps:

[0085] S1. 11 kg of iron tailings powder and 2 kg of steel slag powder (S95 grade) were placed in a mixer for 10 min, 5 kg of mineral powder (specific surface area 390 m 2 / kg), continue mixing for 8 min, add 2 kg of desulfurized gypsum powder, continue mixing for 10 min, to obtain a multi-source solid waste material; divide the multi-source solid waste material into groups I, II, III, and IV, uniformly mix group I with sodium percarbonate to obtain a core mixture; uniformly mix group II with sodium percarbonate and sodium abietate to obtain a light transition layer mixture; uniformly mix group III with sodium abietate to obtain a sub-light transition layer mixture;

[0086] S2. Weigh 1500ml of water into a nano-sprayer, take a small amount of the core mixture of step S1 as the bottom material, start the power to turn on the granulator, and when the speed is stable, evenly spray water mist on the core mixture in the balling machine, until the bottom material is shaped into a sandy material, then add the remaining core mixture, continue to spray water mist, so that the core mixture is evenly wrapped on the sandy material, until it is wrapped into a granular aggregate, to obtain a first structural layer;

[0087] S3. Weigh 1200ml of water into a nano-sprayer, add the light transition layer mixture to the granulator of step S2, and continuously spray water mist until it is wrapped into a ball, to obtain a second structural layer;

[0088] S4. Weigh 600ml of water into a nano-sprayer, add the sub-light transition layer mixture to the granulator of step S3, and continuously spray water mist until it is wrapped into a ball, to obtain a third structural layer;

[0089] S5. Weigh 400ml of water into a nano-sprayer, mix the naphthalene water reducing agent into the water and stir evenly, add the IV group multi-source solid waste material to the granulator of step S4, and continuously spray water mist with naphthalene water reducing agent dissolved in it until it is wrapped into a ball, to obtain a man-made lightweight aggregate blank;

[0090] S6. Place the man-made lightweight aggregate blank of step S5 for 4h, then put it into a steam autoclave, set the pressure to 1.0MPa and the time to 8h, and perform steam curing, and after natural cooling to room temperature, obtain a man-made lightweight aggregate.

[0091] Example 2

[0092] The present embodiment provides a man-made lightweight aggregate with a multi-level gradient structure, which includes a core, a light transition layer, a sub-light transition layer, and a shell distributed from inside to outside;

[0093] The raw materials of the core include 8kg of multi-source solid waste material and 247g of sodium percarbonate, and the mass ratio of the multi-source solid waste material to sodium percarbonate is 32.4:1;

[0094] The raw materials of the light transition layer include 6kg of multi-source solid waste material, 230g of sodium percarbonate, and 20g of sodium abietate, and the total mass of sodium percarbonate and sodium abietate to the mass of multi-source solid waste material is 1:24;

[0095] The raw material of the sub-lightweight transition layer includes 4 kg of multi-source solid waste material and 12 g of ammonium bicarbonate, and the mass ratio of the multi-source solid waste material to the ammonium bicarbonate is 333:1;

[0096] The raw material of the shell includes 2 kg of multi-source solid waste material and 20 g of polycarboxylic acid water reducer, and the mass ratio of the multi-source solid waste material to the polycarboxylic acid water reducer is 100:1.

[0097] The preparation method of the artificial lightweight aggregate in this embodiment includes the following steps:

[0098] S1. 12 kg of iron tailings powder and 3 kg of steel slag powder (S105 grade) were placed in a mixer for mixing for 10 min, 5 kg of mineral powder (specific surface area 370 m 2 / kg) was added, and mixing was continued for 8 min, 2 kg of desulfurization gypsum powder was added, and mixing was continued for 10 min to obtain multi-source solid waste material; the multi-source solid waste material was divided into groups I, II, III and IV, group I was uniformly mixed with sodium percarbonate to obtain core mixture; group II was uniformly mixed with sodium percarbonate and sodium rosin acid to obtain lightweight transition layer mixture; group III was uniformly mixed with ammonium bicarbonate to obtain sub-lightweight transition layer mixture;

[0099] S2. 1920 ml of water was weighed and placed in a nano-sprayer, a small amount of core mixture of step S1 was placed in a granulator as a base material, the power was turned on to start the granulator, and when the speed was stable, water mist was uniformly sprayed on the core mixture in the balling machine, and when the base material was formed, a sandy material was obtained, and the remaining core mixture was added, and water mist was continuously sprayed to uniformly wrap the core mixture on the sandy material until it became a granular aggregate, to obtain a first structural layer;

[0100] S3. 900 ml of water was weighed and placed in a nano-sprayer, and the lightweight transition layer mixture was added to the granulator of step S2, and water mist was continuously sprayed until it was wrapped into a ball, to obtain a second structural layer;

[0101] S4. 720 ml of water was weighed and placed in a nano-sprayer, and the sub-lightweight transition layer mixture was added to the granulator of step S3, and water mist was continuously sprayed until it was wrapped into a ball, to obtain a third structural layer;

[0102] S5. 400 ml of water was weighed and placed in a nano-sprayer, and polycarboxylic acid water reducer was mixed into the water and stirred uniformly, and the fourth group of multi-source solid waste material was added to the granulator of step S4, and water mist with dissolved polycarboxylic acid water reducer was continuously sprayed until it was wrapped into a ball, to obtain an artificial lightweight aggregate green body;

[0103] S6. The artificial lightweight aggregate green body of step S5 was placed for 4 h, then placed in a steam autoclave, the pressure was set to 1.2 MPa, and the time was set to 8 h for steam curing, and after natural cooling to room temperature, an artificial lightweight aggregate was obtained.

[0104] Comparative Example 1

[0105] The raw materials and the amounts of the raw materials used in the artificial aggregate of the present comparative example are the same as those of Example 1, and the difference lies in the different preparation method. The method for preparing the artificial lightweight aggregate of the present comparative example comprises the following steps:

[0106] S1. The iron tailings powder, the steel slag powder (S95 grade), the mineral powder (specific surface area 390 m 2 / kg), the desulfurization gypsum powder, the sodium percarbonate, the sodium abietate, and the naphthalene series water reducing agent were stirred and mixed uniformly to obtain a mixture;

[0107] S2. 3700 ml of water was weighed and loaded into a nano-sprayer, and a small amount of the mixture of step S1 was placed in a granulator as a base material. The power supply was started to turn on the granulator. After the speed was stabilized, the water mist was uniformly sprayed on the mixture in the balling machine. After the base material was formed into a sand-like material, the remaining mixture was added and the water mist was continuously sprayed to uniformly wrap the sand-like material until it was wrapped into a ball to obtain an artificial lightweight aggregate blank;

[0108] S3. The artificial lightweight aggregate blank of step S2 was placed in a steam autoclave and set to a pressure of 1.0 MPa for 8 h for steam curing. After natural cooling to room temperature, an artificial lightweight aggregate was obtained.

[0109] That is, the artificial aggregate obtained by directly mixing all the raw materials uniformly after granulation does not have a multi-level gradient structure.

[0110] Comparative Example 2

[0111] The raw materials and the amounts of the raw materials used in the artificial lightweight aggregate of the present comparative example are basically the same as those of Example 1, and the difference lies in that the sodium abietate is replaced with an equal amount of sodium percarbonate.

[0112] The preparation method of the artificial lightweight aggregate of the present comparative example is basically the same as that of Example 1, and the difference lies in that the sodium abietate in step S1 is replaced with an equal amount of sodium percarbonate.

[0113] That is, the artificial lightweight aggregate of the present comparative example does not contain sodium abietate.

[0114] Comparative Example 3

[0115] The raw materials and the amounts of the raw materials used in the artificial lightweight aggregate of the present comparative example are basically the same as those of Example 1, and the difference lies in that the sodium percarbonate is replaced with an equal amount of sodium abietate.

[0116] The preparation method of the artificial lightweight aggregate of the present comparative example is basically the same as that of Example 1, and the difference lies in that the sodium percarbonate in step S1 is replaced with an equal amount of sodium abietate.

[0117] The artificial lightweight aggregate of the present comparative example does not contain sodium percarbonate.

[0118] Comparative Example 4

[0119] The raw materials and the amounts of the raw materials used in the artificial lightweight aggregate of the present comparative example are basically the same as those of Example 1, except that no naphthalene series water reducing agent is used.

[0120] The preparation method of the artificial lightweight aggregate of the present comparative example is basically the same as that of Example 1, except that no naphthalene series water reducing agent is added to the water in step S5.

[0121] The artificial lightweight aggregate of the present comparative example does not contain naphthalene series water reducing agent.

[0122] Comparative Example 5

[0123] The raw materials and the amounts of the raw materials used in the artificial lightweight aggregate of the present comparative example are the same as those of Example 1, except that the preparation method is different. In step S6 of the present comparative example, the artificial lightweight aggregate green body in step S5 is naturally dried to obtain the artificial lightweight aggregate.

[0124] The artificial lightweight aggregate of the present comparative example does not adopt the hydrothermal synthesis and autoclave curing process.

[0125] Comparative Example 6

[0126] The artificial lightweight aggregate of the present comparative example uses a mixture of 11 kg of iron tailings powder and 9 kg of cement instead of the multi-source solid waste material.

[0127] The preparation method of the artificial lightweight aggregate of the present comparative example is basically the same as that of Example 1, except that the multi-source solid waste material is replaced by a mixture of iron tailings powder and cement.

[0128] The artificial lightweight aggregate of the present comparative example applies cement.

[0129] Application Example

[0130] According to the standard requirements of “Lightweight Aggregate and Its Test Methods” (GBT17431), the cylinder compressive strength, specific strength, bulk density and 1h water absorption rate tests of the artificial lightweight aggregate of Examples 1-2 and Comparative Examples 1-3 were carried out. Two ordinary non-burning lightweight aggregates on the market were also tested in the same way for comparison. Among them, the iron tailings cement-based non-burning lightweight aggregate and the iron tailings slag-based non-burning lightweight aggregate were purchased from Quzhou Jet New Materials Co., Ltd. The test results are shown in Table 4 below.

[0131] Table 4 Test results of Examples 1-2 and Comparative Examples 1-3

[0132]

[0133] As can be seen from the above Table 1, compared with the iron tailings cement-based non-burned light aggregate and the iron tailings slag-based non-burned light aggregate, the bulk density and 1h water absorption of the artificial light aggregate of Example 1-2 are significantly reduced, and the cylinder compressive strength and specific strength are significantly improved, which shows that the artificial light aggregate of the application has excellent performance and good application value.

[0134] Compared with Example 1, the bulk density of Comparative Example 1 has little difference, but the cylinder compressive strength and specific strength have a significant decrease, and the 1h water absorption is high. The reason may be that in Comparative Example 1, all raw materials are directly mixed uniformly, and only one foaming is performed, so that the size of the internal pores of the prepared artificial light aggregate is too large and connected, which finally leads to a significant decrease in the cylinder compressive strength and specific strength of the prepared artificial light aggregate, and a high 1h water absorption.

[0135] Compared with Example 1, the bulk density of Comparative Examples 2-3 only has a little difference, but the 1h water absorption of both is very high, and the cylinder compressive strength and specific strength are significantly decreased. This is because Comparative Example 2 only uses sodium carbonate, and Comparative Example 3 only uses sodium abietate. The size of the internal pores of the artificial light aggregate prepared by Comparative Examples 2-3 is too large or too small, so the 1h water absorption of the artificial light aggregate prepared by Comparative Examples 2-3 is increased, and the specific strength and cylinder compressive strength are also decreased.

[0136] Compared with Example 1, the bulk density and 1h water absorption of Comparative Example 4 are significantly increased, and the cylinder compressive strength and specific strength are also significantly decreased. This may be because the shell of the artificial light aggregate of Comparative Example 4 does not use a naphthalene-based water reducing agent, i.e. no admixture is used, so that the performance of the finally prepared artificial light aggregate is not ideal.

[0137] The performance test results of Comparative Examples 5-6 are close, and the 1h water absorption of both is increased. Compared with Example 1, the cylinder compressive strength of Comparative Examples 5-6 has little difference, but the bulk density is significantly increased, and the specific strength is also significantly decreased. This is because Comparative Example 5 does not have a steam curing process, which leads to poor performance of the finally prepared artificial light aggregate. Comparative Example 6 uses a cement-based, which not only does not improve the performance of the prepared artificial light aggregate, but also increases the cost greatly due to the use of cement.

[0138] The above specific embodiments describe the implementation of the application in detail, but the application is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concepts of the application, the technical solutions of the application can be modified and changed in many simple ways, and these simple modifications all belong to the protection scope of the application.

Claims

1. A method for producing a man-made lightweight aggregate having a multi-stage gradient structure, characterized by, The artificial light aggregate comprises a core, a light transition layer, a sub-light transition layer and a shell which are sequentially distributed from inside to outside; The raw material of the core comprises multi-source solid waste materials and a rapid foaming agent in a mass ratio of (9-49):1; The raw material of the light transition layer comprises multi-source solid waste materials, a rapid foaming agent and a slow-release pore-forming agent in a mass ratio of (300-800):(10-24):1; The raw material of the sub-light transition layer comprises multi-source solid waste materials and a slow-release pore-forming agent in a mass ratio of (99-499):1; The raw material of the shell comprises multi-source solid waste materials and an additive in a mass ratio of (49-199):1; The mass ratio of the multi-source solid waste materials in the core, the light transition layer, the sub-light transition layer and the shell is (3-5):(3-5):2:

1. The method comprises the following steps: Mixing multi-source solid waste materials and a rapid foaming agent in a mass ratio to obtain a core mixture; mixing multi-source solid waste materials, a rapid foaming agent and a slow-release pore-forming agent in a mass ratio to obtain a light transition layer mixture; mixing multi-source solid waste materials and a slow-release pore-forming agent in a mass ratio to obtain a sub-light transition layer mixture; Taking a small amount of the core mixture as a base material to form a sand-like shape, and then adding the remaining core mixture to granulate, while continuously spraying water, to obtain a first aggregate blank body with a core; Adding the light transition layer mixture to the first aggregate blank body to granulate, while continuously spraying water, to obtain a second aggregate blank body with a light transition layer; Adding the sub-light transition layer mixture to the second aggregate blank body to granulate, while continuously spraying water, to obtain a third aggregate blank body with a sub-light transition layer; Adding multi-source solid waste materials to the third aggregate blank body in a proportion, while continuously spraying water in which an additive is dissolved, to obtain an artificial light aggregate blank body with a shell; Placing the artificial light aggregate blank body, autoclave curing and cooling to obtain an artificial light aggregate; In the core of the first aggregate blank body, the mass ratio of water to multi-source solid waste materials is (0.2-0.3):1; in the light transition layer of the second aggregate blank body, the sub-light transition layer of the third aggregate blank body and the shell of the artificial light aggregate blank body, the mass ratio of water to multi-source solid waste materials is (0.1-0.2):1; The multi-source solid waste materials comprise iron tailings, steel slag, desulfurization gypsum and slag in a mass ratio of (4.5-12):(1-3):1:(1.5-5); The additive comprises at least one of a naphthalene series water reducing agent, a polycarboxylic acid water reducing agent and calcium lignosulfonate.

2. The method of producing artificial light-weight aggregates with a multi-stage gradient structure according to claim 1, characterized in that, The rapid foaming agent comprises at least one of sodium percarbonate and hydrogen peroxide.

3. The method of producing artificial light-weight aggregates with a multi-stage gradient structure according to claim 1, characterized in that, The slow-release pore-forming agent comprises at least one of sodium abietate, ammonium bicarbonate, calcium lignosulfonate and ammonium nitrate.

4. The method of producing artificial light-weight aggregates with a multi-stage gradient structure according to claim 1, characterized in that, The autoclave curing condition is that the pressure is 0.8-1.4 MPa and the time is 6-12 h.

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