A kind of lead-zinc tailing ceramsite and its preparation method

Abstract

The present invention belongs to the technical field of resource recycling, and discloses a lead-zinc tailing ceramsite and a preparation method thereof. The lead-zinc tailing ceramsite is mainly made of the following raw materials in parts by mass: 100 parts of lead-zinc tailings; 20-30 parts of limestone tailings; 6-8 parts of active mullite nanoflour; 1-3 parts of glass powder; 8-12 parts of dry sludge powder. A preparation method of the lead-zinc tailing ceramsite is also provided. The present invention uses lead-zinc tailings as the main raw material to prepare the lead-zinc tailing ceramsite. Through the compounding of lead-zinc tailings and limestone tailings, the synergistic effect of the two tailings is realized, and the resource utilization of lead-zinc tailings and limestone tailings is achieved, having good economic and social benefits. The density grade of the ceramsite prepared by the present invention is 600-900, the cylinder compressive strength is 6.8-9.8 MPa, and the water absorption rate is 9.4%-11.4%, having better strength and lower water absorption rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource recycling, and particularly relates to a lead-zinc tailing ceramsite and a preparation method thereof. Background Art

[0002] Lead-zinc tailings are low-grade ores remaining after the extraction of concentrated ores by flotation process during the mining process of lead-zinc enterprises, and most of them are mixed with sand and gravel into a slurry state. At present, the annual production of lead-zinc tailings in the country reaches more than 20 million tons, and the stockpile is still increasing. The stacking of lead-zinc tailings and smelting slag will cause the diffusion of heavy metals. During the long-term stacking process, under the combined action of internal and external factors, harmful components such as acidic water and heavy metal liquids are leached. These harmful components flow into surface rivers and infiltrate into groundwater through rainwater scouring and other means, causing serious heavy metal pollution to the water resources in the mining area and even a larger area. Therefore, the resource utilization of lead-zinc tailings is of great importance.

[0003] At present, lead-zinc tailings have been used as raw materials to produce cement, building wall materials, ceramsite, ceramics, glass, non-fired wall bricks, artificial marble, etc. And because the components of lead-zinc tailings are similar to those of clay, using it as a clay ingredient can produce cement that meets national standards. However, due to the large amount and high heavy metal content of lead-zinc tailings, heavy metal solidification is an important direction during the process of resource utilization. Ceramsite, as an important technical means for solidifying heavy metals, has been applied in lead-zinc tailings. Therefore, preparing lightweight aggregates from lead-zinc tailings can promote the technological progress of lead-zinc tailings reduction, resource utilization, and harmless treatment, and promote the sustainable development of the lead-zinc tailings industry. Summary of the Invention

[0004] Aiming at the problems in the prior art, the present invention proposes a lead-zinc tailing ceramsite and a preparation method thereof.

[0005] In order to achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0006] A lead-zinc tailing ceramsite is mainly made of the following raw materials in parts by mass:

[0007] 100 parts of lead-zinc tailings;

[0008] 20 - 30 parts of limestone tailings;

[0009] 6 - 8 parts of active mullite nanoflour;

[0010] 1 - 3 parts of glass micro-powder;

[0011] 8 - 12 parts of dry sludge powder.

[0012] The active mullite nanoflour is formed by uniformly dispersing mullite particles in a mixed solution of sodium silicate and potassium silicate, then heating and grinding.

[0013] The mass ratio of the mullite particles to sodium silicate and potassium silicate is 1:(1-2):(3-5); the heating temperature is 300-600°C; and the particle size of the active mullite nanopowder is 200-400nm.

[0014] The heating temperature is 300-600℃ because at this temperature sodium silicate and potassium silicate will lose bound water and gel properties, making it easier to grind. When the temperature is too low, it is difficult to grind.

[0015] The particle size of the active mullite nanopowder is 200-400 nm because this particle size can achieve good encapsulation of the mullite nanoparticles by sodium / potassium silicate, while ensuring the integrity and activity stimulation effect of the mullite nanoparticles.

[0016] The particle size of the mullite particles is 50-100 nm, the concentration of the mixed solution of sodium silicate and potassium silicate is 5wt%-15wt%, and the modulus of both sodium silicate and potassium silicate is not higher than 2.

[0017] The modulus of sodium silicate and potassium silicate is not higher than 2 because the modulus is too high, the viscosity is too large, the mullite particles are unevenly dispersed, and the dissolution-promoting effect on silicon dioxide is poor at high temperature.

[0018] The specific surface area of the lead-zinc tailings is 800-1000m 2 / kg, because the specific surface area is too small, silica and alumina are difficult to dissolve, and a strong structure cannot be formed, resulting in lower strength.

[0019] The specific surface area of the limestone tailings is not less than 200m 2 / kg, because the specific surface area is too small and unevenly distributed inside the expanded clay, it is impossible to form a continuous and stable bonding structure, which will cause a decrease in strength.

[0020] The specific surface area of the glass powder is not less than 300m 2 / kg is to ensure uniform dispersion.

[0021] The specific surface area of the dry sludge powder is not less than 200m 2 / kg is to ensure uniform dispersion.

[0022] A method for preparing lead-zinc tailings ceramsite comprises the following steps:

[0023] (1) mixing lead-zinc tailings, limestone tailings, activated mullite nanopowder, glass micropowder and dry sludge powder raw materials in parts by mass, and adding water to prepare a ceramsite embryo;

[0024] (2) Heat the ceramsite embryo to 900 - 980 °C and maintain for 5 - 8 min; then heat to 1200 - 1300 °C and maintain for 8 - 10 min;

[0025] (3) Cool down to 1150 - 1100 °C and maintain for 5 - 10 min; then cool down to 1080 - 1000 °C and maintain for 5 - 10 min; then cool down to 950 - 900 °C and maintain for 5 - 10 min; finally, slowly cool down to room temperature to obtain lead-zinc tailing ceramsite.

[0026] The preparation method of the active mullite nanoflour is as follows: disperse mullite particles evenly in the mixed solution of sodium silicate solution and potassium silicate solution, then heat up and dry until the quality is stable, and grind to 200 - 400 nm under completely dry conditions, which is the active mullite nanoflour.

[0027] In step (3), the staged cooling is carried out for hardening because direct cooling causes disordered hardening of all substances that can produce melt, resulting in a large number of microcracks in the structure, affecting the structural strength and the water absorption of the ceramsite.

[0028] In the process of finally slowly cooling down to room temperature in step (3), the cooling rate is not higher than 10 °C / min because too fast cooling rate is likely to produce cracks.

[0029] Beneficial effects:

[0030] (1) The present invention uses lead-zinc tailings as the main raw material to prepare lead-zinc tailing ceramsite. Through the compounding of lead-zinc tailings and limestone tailings, the synergistic effect of the two tailings is realized, and the resource utilization of lead-zinc tailings and limestone tailings is achieved, with good economic and social benefits. The density grade of the ceramsite prepared by the present invention is 600 - 900, the cylinder compressive strength is 6.8 - 9.8 MPa, and the water absorption rate is 9.4% - 11.4%, having good strength and low water absorption rate.

[0031] (2) The present invention uses sodium silicate and potassium silicate to carry out active modification and excitation on mullite particles to prepare active mullite nanoflour, which improves the dissolution rate and dissolution amount of active substances in lead-zinc tailings and improves the performance of lead-zinc tailing ceramsite. Using the active mullite nanoflour as a crystal seed effectively promotes the formation of mullite crystals in lead-zinc tailing ceramsite under high-temperature conditions and improves the bonding strength of inert particles in the ceramsite.

[0032] (3) The present invention utilizes sludge powder and glass micro-powder to provide sufficient molten silica, which is conducive to the storage of gas bubbles in the molten glass body and improves the porosity of the ceramsite. The sludge provides organic matter to facilitate the generation of gas at high temperature, contributing to the porous structure of the ceramsite. Different from limestone, the temperature at which the organic matter in the sludge burns to form pores is relatively low, mainly leaving a porous structure after the combustion of the organic matter. While for limestone, the gas generated remains in the molten liquid formed after the melting of the glass micro-powder to form gas bubbles.

[0033] (4) In the present invention, the organic matter in the sludge powder burns to generate gas, and calcium carbonate in the limestone tailings decomposes at high temperature to generate carbon dioxide gas, which improves the porosity of the ceramsite. At the same time, the generated calcium oxide reacts with silica at high temperature to form calcium silicate, which wraps and adheres to the lead-zinc tailings particles, improving the strength of the ceramsite. Detailed implementation mode

[0034] The method of the present invention will be described in detail below with reference to specific examples.

[0035] Example 1

[0036] A kind of lead-zinc tailings ceramsite is mainly made of the following raw materials in parts by mass:

[0037] 100 parts of lead-zinc tailings;

[0038] 20 parts of limestone tailings;

[0039] 6 parts of active mullite nanoflour;

[0040] 3 parts of glass micro-powder;

[0041] 8 parts of dry sludge powder.

[0042] The specific surface area of the lead-zinc tailings is 1000m 2 / kg, the specific surface area of the limestone tailings is 200m 2 / kg, and the specific surface area of the glass micro-powder is 300m 2 / kg.

[0043] The preparation method of the active mullite nanoflour is as follows: The mullite particles with a particle size of 80nm are dispersed evenly in a mixed solution of sodium silicate solution with a concentration of 5wt% and potassium silicate, then heated to 300°C and dried until the mass is stable, and then ground to 300nm under completely dry conditions. The mass ratio of the mullite particles to sodium silicate and potassium silicate is 1:2:5.

[0044] The modulus of the sodium silicate is 2.0, and the modulus of the potassium silicate is 1.0.

[0045] The dry sludge powder is the powder obtained by drying the sludge and grinding it to a specific surface area of 200m 2 / kg.

[0046] Preparation method of lead-zinc tailing ceramsite: (1) Mix the above raw materials evenly, add 50 parts of water, and prepare ceramsite embryos through a granulator; (2) Heat the ceramsite embryos to 980 °C and maintain for 5 min; then heat to 1300 °C and maintain for 8 min; (3) Cool down to 1120 °C and maintain for 7 min; then cool down to 1050 °C and maintain for 7 min; then cool down to 920 °C and maintain for 7 min; finally, slowly cool down to room temperature at 5 °C / min to obtain lead-zinc tailing ceramsite.

[0047] Example 2

[0048] A kind of lead-zinc tailing ceramsite is mainly made of the following raw materials in parts by mass:

[0049] 100 parts of lead-zinc tailings;

[0050] 30 parts of limestone tailings;

[0051] 8 parts of active mullite nanoflour;

[0052] 1 part of glass micro powder;

[0053] 12 parts of dry sludge powder.

[0054] The specific surface area of the lead-zinc tailings is 800 m 2 / kg, the specific surface area of the limestone tailings is 300 m 2 / kg, and the specific surface area of the glass micro powder is 400 m 2 / kg.

[0055] The preparation method of the active mullite nanoflour is as follows: disperse the mullite particles with a particle size of 100 nm evenly in a mixed solution of sodium silicate solution with a concentration of 15 wt% and potassium silicate, heat to 600 °C and dry until the quality is stable, and then grind to 400 nm under completely dry conditions. The mass ratio of the mullite particles to sodium silicate and potassium silicate is 1:1:3.

[0056] The modulus of the sodium silicate is 1.0, and the modulus of the potassium silicate is 1.0.

[0057] The dry sludge powder is the powder obtained by drying the sludge and grinding it to a specific surface area of 300 m 2 / kg.

[0058] Preparation method of lead-zinc tailing ceramsite: (1) Mix the above raw materials evenly, add 40 parts of water, and prepare ceramsite embryos through a granulator; (2) Heat the ceramsite embryos to 900 °C and maintain for 8 min; then heat to 1200 °C and maintain for 10 min; (3) Cool down to 1150 °C and maintain for 5 min; then cool down to 1080 °C and maintain for 5 min; then cool down to 950 °C and maintain for 5 min; finally, slowly cool down to room temperature at 10 °C / min to obtain lead-zinc tailing ceramsite.

[0059] Example 3

[0060] A lead-zinc tailings ceramsite is mainly made from the following raw materials in parts by mass:

[0061] 100 parts of lead-zinc tailings;

[0062] 25 parts of limestone tailings;

[0063] 7 parts of active mullite nanoflour;

[0064] 2 parts of glass powder;

[0065] 10 parts of dry sludge powder.

[0066] The specific surface area of the lead-zinc tailings is 900 m 2 / kg, the specific surface area of the limestone tailings is 400 m 2 / kg, and the specific surface area of the glass powder is 450 m 2 / kg.

[0067] The preparation method of the active mullite nanoflour is as follows: mullite particles with a particle size of 50 nm are dispersed evenly in a mixed solution of sodium silicate solution with a concentration of 10 wt% and potassium silicate, then heated to 400 °C and dried until the mass is stable, and then ground to 200 nm under completely dry conditions. The mass ratio of the mullite particles to sodium silicate and potassium silicate is 1:1.5:4.

[0068] The modulus of the sodium silicate is 1.5, and the modulus of the potassium silicate is 1.5.

[0069] The dry sludge powder is powder obtained by drying sludge and grinding it to a specific surface area of 350 m 2 / kg.

[0070] The preparation method of the lead-zinc tailings ceramsite: (1) Mix the above raw materials evenly, add 48 parts of water, and prepare ceramsite embryos through a granulator; (2) Heat the ceramsite embryos to 950 °C and maintain for 6 min; then heat to 1250 °C and maintain for 9 min; (3) Cool down to 1100 °C and maintain for 10 min; then cool down to 1000 °C and maintain for 10 min; then cool down to 900 °C and maintain for 10 min; finally, slowly cool down to room temperature at 3 °C / min to obtain the lead-zinc tailings ceramsite.

[0071] According to the provisions of GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods Part 1 Lightweight Aggregates", the performance indicators of the ceramsites in Examples 1 to 3 were detected, and the results are shown in Table 1.

[0072] Table 1 Performance indicators of the ceramsites in Examples 1 to 3

[0073] Number Density grade Cylinder compressive strength / MPa Water absorption rate / % Example 1 900 9.8 9.8 Example 2 600 6.8 11.4 Example 3 800 8.2 9.4

[0074] As can be seen from Table 1, in Examples 1 to 3, the density grade of the ceramsite is 600 to 900, the cylinder compressive strength is 6.8 to 9.8 MPa, and the water absorption rate is 9.4% to 11.4%. This shows that the ceramsite of the present invention can achieve a very high cylinder compressive strength and a low water absorption rate between the density grades of 600 to 900, realizing the good preparation of lead-zinc tailings ceramsite. From the changes in the density grade and cylinder compressive strength, it can be seen that the difference mainly comes from the content of dry sludge powder. The higher the content of dry sludge powder, the higher the organic matter content, and the more gas is generated under high-temperature conditions, resulting in a decrease in the cylinder compressive strength of the ceramsite and an increase in the water absorption rate. However, under the conditions of the dry sludge powder content controlled in the present invention, the lead-zinc tailings ceramsite can ensure relatively ideal mechanical properties and water absorption rate.

[0075] Comparative Example 1

[0076] The difference from Example 3 is that the specific surface area of the lead-zinc tailings is 600 m 2 / kg.

[0077] Comparative Example 2

[0078] The difference from Example 3 is that the specific surface area of the lead-zinc tailings is 1200 m 2 / kg.

[0079] The properties of the ceramsite in Comparative Examples 1 to 2 were tested, and the results are shown in Table 2.

[0080] Table 2 Performance indexes of the ceramsite in Comparative Examples 1 to 2

[0081]

[0082] As can be seen from the comparison between Comparative Examples 1 to 2 and Example 3 in Table 2, when the specific surface area of the lead-zinc tailings is large, its cylinder compressive strength decreases and the water absorption rate increases. This is mainly because there are a large number of inert particles in the lead-zinc tailings. The particles are too small, resulting in increased shrinkage, more microcracks, poor structural stability, decreased strength, and increased water absorption rate. When the specific surface area of the lead-zinc tailings is small, its cylinder compressive strength decreases and the water absorption rate increases. When the specific surface area is small, there is less vitreous melt, which is difficult to melt out, and the bonding strength is low, resulting in a low cylinder compressive strength. Therefore, selecting lead-zinc tailings with an appropriate specific surface area can obtain ceramsite with better properties.

[0083] Comparative Example 3

[0084] The difference from Example 3 is that limestone tailings are not added.

[0085] Comparative Example 4

[0086] The difference from Example 3 is that 10 parts of limestone tailings are added.

[0087] Comparative Example 5

[0088] The difference from Example 3 is that 40 parts of limestone tailings are added.

[0089] The properties of the ceramsite in Comparative Examples 3 - 5 were tested, and the results are shown in Table 3.

[0090] Table 3 Performance indicators of the ceramsite in Comparative Examples 3 - 5

[0091] Number Quantity of limestone tailings Density grade Cylinder compressive strength / MPa Water absorption rate / % Example 3 25 800 8.2 9.4 Comparative example 3 0 800 4.3 23.5 Comparative example 4 10 800 5.3 14.7 Comparative example 5 40 800 5.6 13.8

[0092] It can be seen from the comparison between Comparative Examples 3 - 5 and Example 3 in Table 3 that as the dosage of limestone tailings increases, the strength of the lead - zinc tailings ceramsite first increases and then decreases, and the water absorption rate first decreases and then increases. The performance of the ceramsite in Example 3 is the best. This is mainly because the limestone tailings provide calcium carbonate, which decomposes to produce gas at high temperature, promoting the porous structure of the ceramsite and resulting in a decrease in strength. After calcium carbonate decomposes to produce carbon dioxide between 900 - 980 °C, calcium oxide is formed. At the same time, when calcined at 1200 - 1300 °C, calcium oxide reacts with molten silica to form calcium silicate, and then the calcium silicate hardens to form a gel structure through slow cooling. Under these conditions, since the formation of calcium silicate consumes silica, with the solubilizing effect of potassium silicate and sodium silicate, more silica in the lead - zinc tailings dissolves out, improving the bonding strength of the ceramsite vitreous body and reducing the water absorption rate. Therefore, the influence of adding limestone on the mechanical properties and water absorption rate of the ceramsite shows positive and negative effects. When the dosage of limestone is low, as its dosage increases, the gas generated at high temperature increases, resulting in an increase in the porosity of the ceramsite structure, which causes a decrease in strength. However, because the calcium silicate formed at 1200 - 1300 °C increases the structural strength, it can completely compensate for the strength decrease caused by the increase in gas. At the same time, because when the gas content is small, mostly closed pores are generated, so it will not lead to an increase in the water absorption rate. Instead, the increased structural density of calcium silicate makes its water absorption rate decrease. But when the dosage is too high, the negative effect caused by too many gas - generated pores increases, making the formed calcium silicate unable to compensate for the strength loss caused by the increase in gas, resulting in a decrease in the strength of the ceramsite and an increase in the water absorption rate. At the same time, too much gas generates connected pores, causing an increase in the water absorption rate. Therefore, choosing an appropriate dosage of limestone tailings can obtain ceramsite with better performance.

[0093] Comparative Example 6

[0094] The difference from Example 3 is that the particle size of mullite is 200 nm.

[0095] The properties of the ceramsite in Comparative Example 6 were tested, and the results are shown in Table 4.

[0096] Table 4 Performance indicators of the ceramsite in Comparative Example 6

[0097] Number Mullite particle size (nm) Density grade Cylinder compressive strength / MPa Water absorption rate / % Example 3 50 800 8.2 9.4 Comparative example 6 200 800 6.4 17.9

[0098] As can be seen from the comparison between Comparative Example 6 and Example 3 in Table 4, the cylinder compressive strength of Comparative Example 6 decreased and the water absorption rate increased. This shows that nano-mullite can act as a seed crystal. When the size of the seed crystal increases, its nucleation effect decreases, resulting in a reduction in the mullite formed under high-temperature conditions. Mullite mainly plays a role in bonding particles to improve strength. When its generation decreases, the strength decreases and the water absorption rate increases.

[0099] Comparative Example 7

[0100] The difference from Example 3 is that only sodium silicate is used in the active mullite nano-powder, and the process of cooling to 920 °C and maintaining for 7 min in step (3) is cancelled.

[0101] Comparative Example 8

[0102] The difference from Example 3 is that only potassium silicate is used in the active mullite nano-powder, and the process of cooling to 1050 °C and maintaining for 7 min in step (3) is cancelled.

[0103] The properties of the ceramsite in Comparative Examples 7-8 were tested, and the results are shown in Table 5.

[0104] Table 5 Performance indicators of the ceramsite in Comparative Examples 7-8

[0105] Number Modified activation of nano-mullite Density grade Cylinder compressive strength / MPa Water absorption rate / % Example 3 Sodium silicate, potassium silicate 800 8.2 9.4 Comparative example 7 Sodium silicate 800 6.2 16.5 Comparative example 8 Potassium silicate 800 6.1 16.0

[0106] As can be seen from the comparison between Comparative Examples 7-8 and Example 3 in Table 5, using only one of sodium silicate or potassium silicate for the activation of nano-mullite activity will cause a decrease in its cylinder compressive strength and an increase in the water absorption rate. This shows that the intermixing use can increase the temperature gradient of the vitreous body dissolution during the reaction, which is beneficial to the improvement of the structural stability, and the intermixing use has a better dissolution-promoting effect.

[0107] Comparative Example 9

[0108] The difference from Example 3 is that the active mullite nano-powder is ground to 100 nm.

[0109] The properties of the ceramsite in Comparative Example 9 were tested, and the results are shown in Table 6.

[0110] Table 6 Performance indicators of the ceramsite in Comparative Example 9

[0111]

[0112] As can be seen from the comparison between Comparative Example 9 and Example 3 in Table 6, grinding the active mullite nanoflour to 100 nm is actually not conducive to the improvement of strength and the decrease of water absorption. This is because the purpose of preparing the active mullite powder is to form an integral structure after mixing sodium / potassium silicate and mullite nanoflour. At the same time, sodium / potassium silicate is alkaline, which can reduce the mullite formation temperature and promote the formation of mullite. Under high-temperature conditions, when the dissolution-promoting effect of sodium / potassium silicate occurs, molten silica and alumina rapidly form a mullite structure under the action of mullite seeds, improving the structural strength of the ceramsite. When the grinding is too fine, it is easy to cause the destruction of the composite structure formed by mullite powder and sodium / potassium silicate, and the separation of sodium / potassium silicate and mullite nanoparticles, which cannot play a good promoting role.

[0113] Comparative Example 10

[0114] The difference from Example 3 is that the modulus of sodium silicate and potassium silicate in the active mullite nanoflour is 3.0.

[0115] The properties of the ceramsite in Comparative Example 10 were tested, and the results are shown in Table 7.

[0116] Table 7 Performance indicators of the ceramsite in Comparative Example 10

[0117]

[0118] As can be seen from the comparison between Comparative Example 10 and Example 3 in Table 7, the cylinder compressive strength of Comparative Example 10 decreased and the water absorption increased. This is because the modulus of sodium / potassium silicate is too high, resulting in too high viscosity and uneven dispersion, and the subsequent dissolution-promoting effect decreases, leading to a reduction in strength.

[0119] Comparative Example 11

[0120] The difference from Example 3 is that in step (3), during the final slow cooling to room temperature, the cooling rate is 20 °C / min.

[0121] Comparative Example 12

[0122] The difference from Example 3 is that during the cooling process, it is directly cooled to room temperature.

[0123] The properties of the ceramsite in Comparative Examples 11 - 12 were tested, and the results are shown in Table 8.

[0124] Table 8 Performance indicators of the ceramsite in Comparative Examples 11 - 12

[0125]

[0126]

[0127] A comparison of Comparative Examples 11-12 and Example 3 in Table 8 shows that in Comparative Example 11, the cooling rate was too rapid, resulting in a decrease in cylinder compressive strength and an increase in water absorption. This is because excessive cooling leads to uneven shrinkage, reduced volume stability, and the formation of cracks, which in turn increases water absorption and reduces strength. In Comparative Example 12, cooling directly to room temperature without a periodic dwell time resulted in structural instability and unstable shrinkage, resulting in a decrease in structural strength and an increase in water absorption.

[0128] Comparative Example 13

[0129] The difference from Example 3 is that the temperature is directly raised to 1250°C during the heating process.

[0130] Comparative Example 14

[0131] The difference from Example 3 is that the maximum temperature is 1180°C.

[0132] The performance of the ceramsite of Comparative Examples 13 to 14 was tested, and the results are shown in Table 9.

[0133] Table 9 Performance indexes of comparative examples 13 to 14 ceramsite

[0134]

[0135] From the comparison of Comparative Examples 13-14 and Example 3 in Table 9, it can be seen that direct heating to the maximum temperature of 1250°C in Comparative Example 13 will lead to excessively concentrated dissolution of the molten glass, excessively concentrated bubble generation, intense bubble generation, bubble fusion to form large bubbles, and a large amount of bubble overflow, resulting in high density and reduced strength. In Comparative Example 14, the maximum temperature was 1180°C, resulting in a significant decrease in strength and increased water absorption. This is because calcination at 1200-1300°C just utilizes calcium oxide and molten silicon dioxide to form calcium silicate, and then slowly cooling the calcium silicate to harden and form a gel structure. Under these conditions, the formation of calcium silicate consumes silicon dioxide, and under the dissolution-promoting effect of potassium silicate and sodium silicate, more silicon dioxide in the lead-zinc tailings is dissolved, thereby improving the bonding strength of the ceramsite glass and reducing the water absorption. When the temperature is not reached, calcium silicate cannot be formed, resulting in a large amount of calcium oxide powder in the product, which not only makes the structure cohesive poor, but also easily absorbs water in the air, causing the structure to expand and destroy, resulting in a decrease in the performance of the ceramsite.

[0136] Comparative Example 15

[0137] The difference from Example 3 is that no active mullite nanopowder is added.

[0138] Comparative Example 16

[0139] The difference from Example 3 is that 3 parts of active mullite nanopowder are added.

[0140] The properties of the ceramsite in Comparative Examples 15 - 16 were detected, and the results are shown in Table 10.

[0141] Table 10 Performance indicators of the ceramsite in Comparative Examples 15 - 16

[0142] Number Quantity of active mullite nano-powder Density grade Cylinder compressive strength / MPa Water absorption rate / % Example 3 7 parts 800 8.2 9.4 Comparative example 15 0 parts 900 6.3 14.8 Comparative example 16 3 parts 800 3.9 29.3

[0143] From the comparison between Comparative Examples 15 - 16 and Example 3 in Table 10, it can be seen that not adding active mullite nanof powder in Comparative Example 15 and adding a small amount of active mullite nanof powder in Comparative Example 16 both lead to a significant decrease in strength and an increase in water absorption. This is mainly because the active mullite nanof powder plays the role of crystal nucleus and dissolution promotion. With insufficient incorporation, the dissolution of the vitreous body in the lead - zinc tailings decreases, and less mullite is formed, resulting in a decrease in strength, an increase in porosity, and an increase in water absorption.

[0144] Comparative Example 17

[0145] The difference from Example 3 is that the mullite nanof powder is directly added without active modification excitation, and sodium silicate and potassium silicate are added simultaneously.

[0146] Comparative Example 18

[0147] The difference from Example 3 is that the mullite nanof powder is directly added without active modification excitation, and sodium silicate and potassium silicate are replaced with an equimolar amount of sodium oxide and potassium oxide.

[0148] The properties of the ceramsite in Comparative Examples 17 - 18 were detected, and the results are shown in Table 11.

[0149] Table 11 Performance indicators of the ceramsite in Comparative Examples 17 - 18

[0150]

[0151] From the comparison between Comparative Examples 17 - 18 and Example 3 in Table

Claims

1. A lead-zinc tailing ceramsite, characterized in that, It is mainly made from the following raw materials in parts by mass: 100 parts of lead-zinc tailings; 20 - 30 parts of limestone tailings; 6 - 8 parts of active mullite nanoflour; 1 - 3 parts of glass microflour; 8 - 12 parts of dry sludge powder; The active mullite nanoflour is made by dispersing mullite particles evenly in a mixed solution of sodium silicate and potassium silicate, then heating up and grinding. The heating temperature is 300 - 600 °C; The preparation method of the lead-zinc tailings ceramsite is as follows: (1) Mix the raw materials of lead-zinc tailings, limestone tailings, active mullite nanoflour, glass microflour and dry sludge powder evenly in parts by mass, and add water to prepare a ceramsite embryo; (2) Heat the ceramsite embryo to 900 - 980 °C and maintain for 5 - 8 min; then heat to 1200 - 1300 °C and maintain for 8 - 10 min; (3) Cool down to 1150 - 1100 °C and maintain for 5 - 10 min; then cool down to 1080 - 1000 °C and maintain for 5 - 10 min; then cool down to 950 - 900 °C and maintain for 5 - 10 min; finally, slowly cool down to room temperature to obtain the lead-zinc tailings ceramsite.

2. The ceramsite made from lead-zinc tailings according to claim 1, characterized in that The mass ratio of the mullite particles, sodium silicate and potassium silicate is 1:(1 - 2):(3 - 5); The particle size of the mullite particles is 50 - 100 nm, the concentration of the mixed solution of sodium silicate and potassium silicate is 5wt% - 15wt%, and the modulus of both sodium silicate and potassium silicate is not higher than 2; The particle size of the active mullite nanoflour is 200 - 400 nm.

3. The ceramsite made from lead-zinc tailings according to claim 1, wherein The specific surface area of the lead-zinc tailings is 800 to 1000 m 2 / kg.

4. The ceramsite made from lead-zinc tailings according to claim 1, wherein The specific surface area of the limestone tailings is not less than 200 m 2 / kg.

5. The ceramsite made from lead-zinc tailings according to claim 1, wherein, The specific surface area of the glass micropowder is not less than 300 m 2 / kg.

6. The ceramsite made from lead-zinc tailings according to claim 1, wherein The specific surface area of the dry sludge powder is not less than 200 m 2 / kg.

7. The ceramsite made from lead-zinc tailings according to claim 1, characterized in that, The preparation method of the active mullite nanoflour is: after dispersing the mullite particles evenly in the sodium silicate solution and the mixed solution of potassium silicate, heat up and dry until the quality is stable, and then grind to 200 - 400 nm under completely dry conditions, which is the active mullite nanoflour.

8. The ceramsite made from lead-zinc tailings according to claim 1, characterized in that, In the process of finally slowly cooling down to room temperature in step (3), the cooling rate is not higher than 10 °C / min.

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