Light aggregate based on tungsten tailings as well as preparation method and application of light aggregate

Abstract

The invention provides a lightweight aggregate based on tungsten tailings and a preparation method and application thereof, and the preparation method comprises the following steps: mixing 60%-90% of tungsten tailings, 5%-20% of fly ash and 1%-20% of a foaming agent to obtain a solid raw material, adding an additive and a binder, and granulating to obtain a green body; the additives are glass powder and zeolite powder; the green body is subjected to two-stage sintering, sintering is conducted for 5-60 min at the temperature of 400-500 DEG C in the first stage, sintering is conducted for 20-120 min at the temperature of 900-1200 DEG C in the second stage, cooling is conducted to the room temperature, and the lightweight aggregate is obtained. The lightweight aggregate prepared by the invention is internally provided with multiple micropores, but is very compact in structure, and strip substances crossed in the pores can be observed under a microscope, so that the lightweight aggregate has very high strength and is very environment-friendly, solid wastes are utilized, and meanwhile, heavy metal elements in the solid wastes are solidified; and the leaching concentration is far lower than the related standard.

Description

Technical Field

[0001] The invention relates to the technical field of building functional materials, and in particular to a light aggregate based on tungsten tailings, and a preparation method and application thereof. Background Art

[0002] Tungsten tailings are solid wastes left after extracting tungsten-containing minerals from tungsten-containing ores through beneficiation. The mineral composition includes garnet, mica, calcite, fluorite, etc. The chemical composition is mainly silicon dioxide, aluminum oxide, iron oxide, magnesium oxide, calcium oxide, and calcium fluoride. Some tungsten tailings also contain a small amount of polymetallic minerals, such as molybdenum, bismuth, and rubidium. Among them, garnet has a higher hardness, and the content of silicon dioxide, aluminum oxide, and iron oxide is close to that of ceramics, glass and other building materials. Its application in the preparation of building materials is its main way of disposal. The low grade of tungsten ore will lead to a large amount of tailings during the mining process, and the accumulation of tailings will have a lasting and far-reaching adverse impact on the environment. Therefore, many researchers have proposed a variety of methods to treat tailings. One is to recycle certain metals and non-metals in tungsten tailings, but the recycled amount only accounts for a small part of the tailings, and there is basically no effect on the bulk disposal of tailings; the second is to use them for the preparation of building materials, such as microcrystalline glass, cement, geopolymers, ceramics, gel materials, etc. These methods can effectively reduce the accumulation of tungsten tailings, but new building materials still need to be developed to increase the disposal amount.

[0003] Light aggregate refers to aggregate with a bulk density less than 1200kg / m 3 The coarse and fine aggregates generally have the characteristics of low density, high water absorption, heat preservation, earthquake resistance, etc. They are widely used and have broad prospects in building materials, water treatment materials, sound insulation and heat preservation wall materials, gardening substrates, permeable pavement materials, etc. Common light aggregates are generally prepared from domestic sludge or fly ash as the main raw materials. Sludge light aggregate can make the aggregate have extremely low density due to the very light organic matter of the raw material, but there are problems such as low silica content and high ignition loss. In the production process, more silicon sources need to be added and excessive ignition loss will cause drying shrinkage, which will seriously cause aggregate cracking and reduce production efficiency. At the same time, auxiliary agents need to be added to solidify the heavy metal ions in the sludge to meet environmental requirements. At present, there are few reports on the preparation of light aggregates from tungsten tailings. Light aggregates have high utilization rate, large processing capacity, high production efficiency, and can be consumed on a large scale. They can be used as a way to efficiently realize the high-quality utilization of tungsten tailings. However, it is still very difficult to obtain light aggregates with light weight, high strength and good heavy metal ion solidification effect. Summary of the invention

[0004] Based on this, the present invention provides a method for preparing a lightweight, high-strength, and heavy metal ion-cured lightweight aggregate.

[0005] A method for preparing light aggregate based on tungsten tailings comprises the following steps:

[0006] According to the mass percentage, 60% to 90% of tungsten tailings, 5% to 20% of fly ash, and 1% to 20% of a foaming agent are mixed to obtain a solid raw material, and an admixture and a binder are added to granulate to obtain a green body; the amount of the admixture added is 1% to 3% of the mass of the solid raw material, the amount of the binder added is 2% to 4% of the mass of the solid raw material, and the admixtures are glass powder and zeolite powder;

[0007] The green body is sintered in two stages: the first stage is sintered at 400°C to 500°C for 5 to 60 minutes, and the second stage is sintered at 900°C to 1200°C for 20 to 120 minutes, and then cooled to room temperature to obtain the light aggregate.

[0008] In one of the embodiments, the mass ratio of the glass powder to the zeolite powder is 1.8-2.2:1.

[0009] In one embodiment, the main chemical components of the tungsten tailings are, by mass percentage, 25% to 45% SiO2, 5% to 20% Al2O3, 2% to 15% Fe2O3, 6% to 30% CaO, 0.5% to 5% MgO, 0.1% to 1% SO3, 0.5% to 5% Na2O, 0.5% to 5% K2O, 0.1% to 2% TiO2 and 0.5% to 5% MnO2. Preferably, the particle size of the tungsten tailings is 200 to 800 meshes.

[0010] In one of the embodiments, the main chemical components of the fly ash are, by mass percentage, 45% to 55% SiO2, 20% to 25% Al2O3, 5% to 10% Fe2O3, 1% to 5% CaO, 1% to 5% MgO, 0.1% to 1% SO3, 0.5% to 2% Na2O and 1% to 3% K2O.

[0011] In one embodiment, the foaming agent is selected from one or more of hydroxymethyl cellulose, hydroxyethyl methyl cellulose, stearic acid, sawdust, calcium carbonate, sodium carbonate, carbon powder and silicon carbide.

[0012] In one embodiment, the binder is selected from one or more of sodium silicate, polyethylene glycol, polyacrylamide and polyvinyl alcohol.

[0013] In one embodiment, the mass percentage of the tungsten tailings is 77% to 90%, the mass percentage of the fly ash is 8% to 9%, the foaming agent is stearic acid or sawdust with a mass percentage of 1% to 15%, the added amount of the admixture and the binder is 3% of the mass of the solid raw material, and the binder is sodium silicate or polyacrylamide.

[0014] In one embodiment, the first stage of the two-stage sintering is sintered at 450° C. to 500° C. for 20 to 30 minutes, and the second stage is sintered at 1090° C. to 1150° C. for 30 to 60 minutes.

[0015] The present invention also provides a light aggregate based on tungsten tailings, which is prepared according to the above preparation method.

[0016] The invention also provides a hollow brick, which comprises the above-mentioned light aggregate as well as cement, quartz sand and silica fume.

[0017] In one embodiment, the hollow brick comprises 30wt% to 70wt% lightweight aggregate, 7wt% to 15wt% cement, 0.5wt% to 1wt% silica fume and the balance quartz sand. Preferably, the hollow brick comprises 60wt% to 70wt% lightweight aggregate, 9wt% to 12wt% cement, 0.6wt% to 0.8wt% silica fume and the balance quartz sand.

[0018] The above solution of the present invention has the following beneficial effects:

[0019] The light aggregate prepared from tungsten tailings in the present invention has a particle size of 2 to 20 mm and can meet multiple bulk density requirements (600 to 1100 kg / m 3 ), the staged calcination process helps to improve the strength of light aggregate and solidify heavy metals, among which the diopside and calcium feldspar formed during high-temperature sintering of light aggregate are the main sources of its strength. The added foaming agent has both burn-out and foaming effects, which synergistically reduce the bulk density of light aggregate and help avoid the volume shrinkage of particles during the sintering process. The compressive strength, softening coefficient, particle shape coefficient and other standards of the obtained light aggregate meet the requirements of the national standard GB / T 17431.1-2010 "Light Aggregate and Its Test Methods Part 1 Light Aggregate", and the heavy metal ion leaching meets the requirements of Class III water quality in the national standard GB 3838-2002 "Surface Water Environmental Quality Standard".

[0020] The above-mentioned lightweight aggregate prepared based on tungsten tailings has multiple micropores inside (such as Figure 1 The structure is very compact, and under a microscope, it can be seen that there are long strips of material crossing inside the holes (such as Figure 2As shown in the figure, the light aggregate has a very high strength, which can far exceed the standard by more than 10 times. Moreover, it has a wide range of stacking density grades and is lightweight and high-strength. Applying it to hollow cement bricks can effectively reduce the density of hollow bricks and obtain hollow cement bricks of different density grades. At the same time, it helps to improve the strength of hollow bricks, and is not limited to application in hollow cement bricks. In addition, the light aggregate is very environmentally friendly. Under the synergistic effect of glass powder and zeolite powder, it not only utilizes solid waste, but also solidifies the heavy metal elements therein, making its leaching concentration far lower than the relevant standards, and has a significant solidification effect on heavy metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a microscopic photograph of the interior of the lightweight aggregate prepared based on tungsten tailings in Example 1 of the present invention;

[0022] Figure 2 This is a microscopic photograph of the interior of the pores of the lightweight aggregate prepared based on tungsten tailings in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. The reagents and instruments used in the examples are conventionally selected in the art unless otherwise specified. The experimental methods without specific conditions in the examples are implemented according to conventional conditions, such as the conditions described in the literature, books or methods recommended by the manufacturer.

[0025] The following is a specific embodiment, in which the chemical compositions of the tungsten tailings and fly ash used are shown in Table 1. The main minerals in the tungsten tailings are chlorite, mica, garnet, calcite, fluorite, quartz, etc. In addition, it also contains a small amount of lead, zinc, chromium and other elements.

[0026] Table 1 Chemical composition of raw materials / %

[0027]

[0028] Example 1

[0029] A preparation method of a light aggregate with a density grade of 1100 is as follows: according to the mass percentage, 90% of tungsten tailings (200 mesh), 9% of fly ash and 1% of sawdust are mixed to obtain a solid raw material, 3% of the mass of the solid raw material sodium silicate, 2% of the mass of the solid raw material glass powder and 1% of the mass of the solid raw material zeolite powder are added, and then an appropriate amount of water is added to mix fully, granulate, and then place it in a ventilated place to dry naturally to obtain a green body. The green body is placed in a high-temperature furnace and sintered in two stages: the first stage is sintered at 450°C for 20 minutes, and the second stage is sintered at 1090°C for 30 minutes. Finally, it is cooled and taken out to obtain a light aggregate, which has a compressive strength of 32.49MPa, a water absorption rate of 5.14%, and a bulk density of 1.035g / cm 3 .

[0030] According to the mass percentage, 69.4% lightweight aggregate was mixed with 10% cement (PO32.5 cement), 20% quartz sand, and 0.6% silica fume, and water was added to mix evenly to make a concrete mixture, which was then molded into hollow bricks. After curing for 28 days, the density was measured to be 1275kg / m 3 The strength is 30.46MPa (standard 10MPa) and the water absorption rate is 12.60% (standard 35%), which meets the application requirements of partition walls, internal and external walls in building materials.

[0031] Example 2

[0032] A preparation method of a light aggregate with a density grade of 1000 is as follows: according to the mass percentage, 86% of tungsten tailings (200 mesh), 9% of fly ash and 5% of sawdust are mixed to obtain a solid raw material, 3% of the mass of the solid raw material is added with sodium silicate, 2% of the mass of the solid raw material is added with glass powder and 1% of the mass of the solid raw material is added with zeolite powder, and then an appropriate amount of water is added to mix thoroughly, granulate, and then place it in a ventilated place to dry naturally to obtain a green body. The green body is placed in a high-temperature furnace and sintered in two stages: the first stage is sintered at 450°C for 20 minutes, and the second stage is sintered at 1120°C for 30 minutes. Finally, it is cooled and taken out to obtain a light aggregate with a compressive strength of 14.82MPa, a water absorption rate of 8.75%, and a bulk density of 0.973g / cm 3 .

[0033] According to the mass percentage, 63.4% lightweight aggregate was mixed with 12% cement (PO32.5 cement), 24% quartz sand, and 0.6% silica fume, and water was added to mix evenly to make a concrete mixture, which was then molded into hollow bricks. After curing for 28 days, the density was measured to be 1211kg / m 3 The strength is 17.13MPa (standard 10MPa) and the water absorption rate is 15.13% (standard 35%), which meets the application requirements of partition walls, internal and external walls in building materials.

[0034] Example 3

[0035] A preparation method of a light aggregate with a density grade of 900 is as follows: according to the mass percentage, 81% of tungsten tailings (200 mesh), 9% of fly ash and 10% of sawdust are mixed to obtain a solid raw material, 3% of the mass of the solid raw material is added with sodium silicate, 2% of the mass of the solid raw material is added with glass powder and 1% of the mass of the solid raw material is added with zeolite powder, and then an appropriate amount of water is added to mix them fully, granulate them, and then place them in a ventilated place to dry naturally to obtain a green body. The green body is placed in a high-temperature furnace and sintered in two stages: the first stage is sintered at 450°C for 20 minutes, and the second stage is sintered at 1120°C for 30 minutes. Finally, it is cooled and taken out to obtain a light aggregate, which has a compressive strength of 14.78MPa, a water absorption rate of 9.01%, and a bulk density of 0.845g / cm 3 .

[0036] According to the mass percentage, 63.4% lightweight aggregate was mixed with 12% cement (PO32.5 cement), 24% quartz sand, and 0.6% silica fume, and water was added to mix evenly to make a concrete mixture, which was then molded into hollow bricks. After curing for 28 days, the density was measured to be 1143kg / m 3 The strength is 17.97MPa (standard 10MPa) and the water absorption rate is 15.31% (standard 35%), which meets the application requirements of partition walls, internal and external walls in building materials.

[0037] Example 4

[0038] A preparation method of a light aggregate with a density grade of 800 is as follows: according to the mass percentage, 77% of tungsten tailings (200 mesh), 8% of fly ash and 15% of sawdust are mixed to obtain a solid raw material, 3% of the mass of the solid raw material is added with sodium silicate, 2% of the mass of the solid raw material is added with glass powder and 1% of the mass of the solid raw material is added with zeolite powder, and then an appropriate amount of water is added to mix thoroughly, granulate, and then place it in a ventilated place to dry naturally to obtain a green body. The green body is placed in a high-temperature furnace and sintered in two stages: the first stage is sintered at 450°C for 20 minutes, and the second stage is sintered at 1120°C for 30 minutes. Finally, it is cooled and taken out to obtain a light aggregate, which has a compressive strength of 13.61MPa, a water absorption rate of 9.34%, and a bulk density of 0.782g / cm 3 .

[0039] According to the mass percentage, 63.4% lightweight aggregate was mixed with 12% cement (PO32.5 cement), 24% quartz sand, and 0.6% silica fume, and water was added to mix evenly to make a concrete mixture, which was then molded into hollow bricks. After curing for 28 days, the density was measured to be 1043kg / m 3 The strength is 16.95MPa (standard 7.5MPa), and the water absorption rate is 15.48% (standard 35%), which meets the application requirements of partition walls, internal and external walls in building materials.

[0040] Example 5

[0041] A preparation method of a light aggregate with a density grade of 700 is as follows: according to the mass percentage, 72% of tungsten tailings (200 mesh), 8% of fly ash and 20% of sawdust are mixed to obtain a solid raw material, 3% of the mass of the solid raw material is added with sodium silicate, 2% of the mass of the solid raw material is added with glass powder and 1% of the mass of the solid raw material is added with zeolite powder, and then an appropriate amount of water is added to mix them fully, granulate them, and then place them in a ventilated place to dry naturally to obtain a green body. The green body is placed in a high-temperature furnace and sintered in two stages: the first stage is sintered at 450°C for 20 minutes, and the second stage is sintered at 1120°C for 30 minutes. Finally, it is cooled and taken out to obtain a light aggregate, which has a compressive strength of 12.37MPa, a water absorption rate of 9.67%, and a bulk density of 0.686g / cm 3 .

[0042] According to the mass percentage, 63.4% lightweight aggregate was mixed with 12% cement (PO32.5 cement), 24% quartz sand, and 0.6% silica fume, and water was added to mix evenly to make a concrete mixture, which was then molded into hollow bricks. After curing for 28 days, the density was measured to be 957kg / m 3 The strength is 15.87MPa (standard 7.5MPa), and the water absorption rate is 15.79% (standard 35%), which meets the application requirements of partition walls, internal and external walls in building materials.

[0043] Example 6

[0044] A preparation method of a light aggregate with a density grade of 600 is as follows: according to the mass percentage, 63% of tungsten tailings (200 mesh), 17% of fly ash and 20% of stearic acid are mixed to obtain a solid raw material, 3% of the mass of the solid raw material sodium silicate, 2% of the mass of the solid raw material glass powder and 1% of the mass of the solid raw material zeolite powder are added, and then an appropriate amount of water is added to mix fully, granulate, and then place it in a ventilated place to dry naturally to obtain a green body. The green body is placed in a high-temperature furnace and sintered in two stages: the first stage is sintered at 450°C for 20 minutes, and the second stage is sintered at 1120°C for 30 minutes. Finally, it is cooled and taken out to obtain a light aggregate, which has a compressive strength of 5.37MPa, a water absorption rate of 9.43%, and a bulk density of 0.587g / cm 3 .

[0045] According to the mass percentage, 69.4% lightweight aggregate was mixed with 9% cement (PO32.5 cement), 21% quartz sand, and 0.6% silica fume, and water was added to mix evenly to make a concrete mixture, which was then molded into hollow bricks. After curing for 28 days, the density was measured to be 878kg / m 3The strength is 9.79MPa (standard 5MPa) and the water absorption rate is 15.88% (standard 35%), which meets the application requirements of partition walls, internal and external walls in building materials.

[0046] Comparative Example 1

[0047] According to the mass percentage, 90% of tungsten tailings (200 mesh) and 10% of fly ash are mixed to obtain solid raw materials, and then an appropriate amount of water is added for full mixing and granulation, and then it is placed in a ventilated place for natural drying to obtain a green body. The green body is placed in a high-temperature furnace and sintered in two stages: the first stage is sintered at 450°C for 20 minutes, and the second stage is sintered at 1120°C for 30 minutes. Finally, it is cooled and taken out to obtain a light aggregate with a compressive strength of 19.93MPa, a water absorption rate of 5.47%, and a bulk density of 1.187g / cm 3 .

[0048] Comparative Example 2

[0049] According to the mass percentage, 60% of tungsten tailings (200 mesh), 23% of fly ash and 17% of quartz are mixed to obtain solid raw materials, and then an appropriate amount of water is added for full mixing, granulation is performed, and then it is placed in a ventilated place for natural drying to obtain a green body. The green body is placed in a high-temperature furnace and sintered in two stages: the first stage is sintered at 450°C for 20 minutes, and the second stage is sintered at 1120°C for 30 minutes. Finally, it is cooled and taken out to obtain a light aggregate with a compressive strength of 4.56MPa, a water absorption rate of 6.91%, and a bulk density of 1.216g / cm 3 .

[0050] Comparative Example 3

[0051] The steps of this comparative example are basically the same as those of Example 1, except that zeolite powder is not added and the amount of glass powder added is 3% of the mass of the solid raw material. The obtained lightweight aggregate has a compressive strength of 28.73 MPa, a water absorption rate of 5.68%, and a bulk density of 1.046 g / cm 3 .

[0052] Comparative Example 4

[0053] The steps of this comparative example are basically the same as those of Example 1, except that no glass powder is added and the amount of zeolite powder added is 3% of the mass of the solid raw material. The obtained lightweight aggregate has a compressive strength of 26.68 MPa, a water absorption rate of 7.35%, and a bulk density of 1.023 g / cm 3 .

[0054] Comparative Example 5

[0055] The steps of this comparative example are basically the same as those of Example 1, except that the glass powder is replaced by hydroxyapatite. The obtained lightweight aggregate has a compressive strength of 27.84 MPa, a water absorption rate of 7.65%, and a bulk density of 1.033 g / cm 3 .

[0056] According to the requirements of GB 5085.3-2007 "Hazardous Waste Identification Standard Leaching Toxicity Identification", the leaching solution was prepared and the leaching toxicity identification was carried out for the light aggregates fired in Examples 1 to 6 and Comparative Examples 1 to 5, and the leaching results were compared with the requirements of GB 3838-2002 "Surface Water Environmental Quality Standard". The results are shown in Table 2, which not only illustrate that the various light aggregates prepared in the examples and comparative examples are not hazardous wastes, but also illustrate that the leaching concentration of heavy metal ions in the light aggregates of each example has reached the requirements of Class III water quality standards of GB 3838-2002 "Surface Water Environmental Quality Standard". It can be seen that the synergistic effect of the glass powder and zeolite powder added in the examples plays an important role in the solidification of heavy metal ions, and the effect is remarkable. Further, the results fully show that the prepared light aggregate is environmentally friendly and pollution-free, can be used for agricultural water retention and filtration without polluting water quality, and broadens the application range of light aggregate.

[0057] Table 2 Fixation effect of heavy metal elements in lightweight aggregate

[0058]

[0059] The light aggregate products fired in Examples 1 to 6 and Comparative Examples 1 to 5 were compared with the national standard GB / T17431.1-2010 "Light aggregate and its test method Part 1 Light aggregate". The results are shown in Table 3, indicating that the performance of light aggregate with a density grade of 600 and above prepared by tungsten tailings meets the standard requirements.

[0060] Table 3 Lightweight aggregate properties

[0061]

[0062]

[0063] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing light aggregate based on tungsten tailings, characterized in that: The following steps are involved: According to the mass percentage, 60% to 90% of tungsten tailings, 5% to 20% of fly ash, and 1% to 20% of a foaming agent are mixed to obtain a solid raw material, and an admixture and a binder are added to granulate to obtain a green body; the amount of the admixture added is 1% to 3% of the mass of the solid raw material, the amount of the binder added is 2% to 4% of the mass of the solid raw material, and the admixtures are glass powder and zeolite powder; The green body is sintered in two stages: the first stage is sintered at 400°C to 500°C for 5 to 60 minutes, and the second stage is sintered at 900°C to 1200°C for 20 to 120 minutes, and then cooled to room temperature to obtain the light aggregate.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the glass powder to the zeolite powder is 1.8-2.2:

1.

3. The preparation method according to claim 1, characterized in that: According to mass percentage, the main chemical components of the tungsten tailings are: 25% to 45% SiO2, 5% to 20% Al2O3, 2% to 15% Fe2O3, 6% to 30% CaO, 0.5% to 5% MgO, 0.1% to 1% SO3, 0.5% to 5% Na2O, 0.5% to 5% K2O, 0.1% to 2% TiO2 and 0.5% to 5% MnO2.

4. The preparation method according to claim 1, characterized in that: According to mass percentage, the main chemical components of the fly ash are: 45% to 55% SiO2, 20% to 25% Al2O3, 5% to 10% Fe2O3, 1% to 5% CaO, 1% to 5% MgO, 0.1% to 1% SO3, 0.5% to 2% Na2O and 1% to 3% K2O.

5. The preparation method according to claim 1, characterized in that: The foaming agent is selected from one or more of hydroxymethyl cellulose, hydroxyethyl methyl cellulose, stearic acid, sawdust, calcium carbonate, sodium carbonate, carbon powder and silicon carbide.

6. The preparation method according to claim 1, characterized in that: The binder is selected from one or more of sodium silicate, polyethylene glycol, polyacrylamide and polyvinyl alcohol.

7. The preparation method according to claim 1, characterized in that: The mass percentage of the tungsten tailings is 77% to 90%, the mass percentage of the fly ash is 8% to 9%, the foaming agent is stearic acid or sawdust with a mass percentage of 1% to 15%, the addition amount of the admixture and the binder is both 3% of the mass of the solid raw material, and the binder is sodium silicate or polyacrylamide.

8. The preparation method according to claim 1, characterized in that: The first stage of the two-stage sintering is sintered at 450° C. to 500° C. for 20 to 30 minutes, and the second stage is sintered at 1090° C. to 1150° C. for 30 to 60 minutes.

9. A light aggregate based on tungsten tailings, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 8.

10. A hollow brick, characterized in that: The invention comprises the lightweight aggregate as claimed in claim 9 as well as cement, quartz sand and silica fume.

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