A method for preparing foamed ceramics using lead smelting fuming slag as raw material and foamed ceramics prepared by the method

Abstract

The application relates to a preparation method of foamed ceramics taking lead smelting fuming residues as raw materials and the foamed ceramics prepared by the method, and belongs to the field of building materials. The preparation method comprises the following steps: (1) drying, grinding and screening the lead smelting fuming residues; (2) mixing the fuming residues with pulverized coal, and reacting according to a carbon mixing ratio, a reduction temperature and a reduction time, then heating to a melting separation temperature for heat preservation, and then cooling in the furnace to separate metal iron and melting separation residues; (3) melting the obtained melting separation residues, then water quenching, drying, grinding, screening and obtaining basic glass powder; (4) adding auxiliary materials, fluxing agents and foaming agents into the obtained basic glass powder, and ball-milling and mixing the materials; and (5) loading the powder into a corundum crucible, leveling and compacting, and then performing sintering. The method can modify the reduction residues to prepare foamed ceramics, and can also recycle metal iron. The prepared foamed ceramics have the characteristics of light weight, good heat insulation performance, high residue utilization rate and high product added value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of building materials, and particularly relates to a foamed ceramic taking lead smelting fuming slag as raw material and a preparation method thereof. BACKGROUND

[0002] The lead smelting fuming slag is a waste slag produced in a primary lead smelting system in a primary lead smelting process by fire refining-electrolytic refining. According to statistics, 7100 kg of fuming slag will be discharged in the primary lead smelting system for producing 1 ton of lead, which will result in a large amount of storage of the fuming slag. According to statistics, 1 million tons of waste slag will need more than 670 square meters of land, on the other hand, the fuming slag contains some highly migratory toxic elements such as lead, zinc and cadmium. The accumulation process of the toxic elements will pollute the surrounding environment of the soil and groundwater, and the toxic elements have the risk of enrichment in animals and plants, which will finally directly or indirectly endanger human health. In addition, the fuming slag contains a large amount of valuable metals such as silicon, calcium and iron, which can be utilized as secondary resources. Therefore, it is an urgent problem to be solved to realize the resource utilization and harmless utilization of the fuming slag to ensure the sustainable development of the lead smelting industry.

[0003] At present, common building insulation materials include mineral wool, polyurethane foam plastic, polystyrene foam board, aerated concrete and the like. At present, the organic insulation material is mainly used in the market. Although the organic insulation material has the advantages of light weight, good thermal insulation property, simple production process and the like, it has the fatal defects of poor fireproof performance and large safety hidden danger. In practical application, most of the insulation materials have problems such as hollowing, peeling, cracking, water absorption, frost heaving and the like after being used for less than 10 years, and even the whole thermal insulation layer and the facing layer of the outer wall are induced to fall off. In view of the problems of the organic insulation material, the foamed ceramic as a new type of thermal insulation wall material has the characteristics of light weight, high strength, fireproof, good thermal insulation performance, non-toxic, corrosion resistance, non-water absorption, non-aging, good cement mortar adhesion and the like. The foamed ceramic used as the outer wall thermal insulation material can effectively solve the above problems. SUMMARY

[0004] In view of the above problems, the present application provides a preparation method of foamed ceramic taking lead smelting fuming slag as raw material and foamed ceramic prepared by the method. The method can modify the reduction residue to prepare the foamed ceramic and recover the metal iron at the same time. The prepared foamed ceramic has the characteristics of light weight, good thermal insulation performance, high residue utilization rate and high product added value.

[0005] A preparation method of foamed ceramic taking lead smelting fuming slag as raw material, the method comprises the following steps:

[0006] (1) The lead smelting fuming slag is dried, ground and sieved, and stored for standby use;

[0007] (2) The treated lead smelting fuming residue is mixed with pulverized coal, and then reacted according to a certain carbon ratio, reduction temperature and reduction time. After the reaction, the temperature is increased to a melting separation temperature for heat preservation. After the heat preservation, the furnace is cooled to room temperature, and then metal iron and melting separation residue are separated;

[0008] (3) The melting separation residue is melted in a high-temperature furnace. After melting, water quenching, drying, grinding and screening, a base glass powder (see Table 1 for chemical composition) is obtained, which is used as a raw material for preparing foamed ceramics;

[0009] (4) The base glass powder obtained in step (3) is added with auxiliary materials, fluxing agents and foaming agents, and then ball-mixed;

[0010] (5) The ball-mixed powder is loaded into a corundum crucible, flattened and compacted, and then placed in a high-temperature furnace for sintering according to a certain heat treatment system.

[0011] In the above preparation process:

[0012] In step (1), the screening size is -200 mesh.

[0013] In step (2), the fixed carbon content of the pulverized coal is 70.55%-76.35%; the carbon ratio C / O (molar ratio) is 0.8-1.8; the reduction temperature is 900-1400℃, and the reduction time is 20-100min; the melting separation temperature is 1500-1600℃, and the heat preservation time is 100-130min; the reaction equation of this step (2) is: C+2FeO=2Fe+CO2.

[0014] In step (3), the melting temperature is 1450-1500℃, and the melting time is 150-180min.

[0015] Table 1 Chemical composition of base glass powder (wt%)

[0016]

[0017] In step (4), the auxiliary material is quartz sand (25-30wt%); the fluxing agent is borax (6wt%); the foaming agent is AlN (0-1.2wt%); and the ball-mixing process is carried out by a planetary ball mill with a rotation speed of 230r / min and a ball-milling time of 150min.

[0018] In the step (6), the specific steps are as follows: the powder obtained by ball milling is loaded into a corundum crucible with a 1mm-thick refractory aluminum silicate paper laid on the inner wall and the bottom, and after being laid flat and compacted, the volume of the powder accounts for about 50% of the volume of the corundum crucible, then the crucible is placed in a high-temperature furnace, and the temperature is raised from room temperature to 400 DEG C at a rate of 5 DEG C / min, and then the temperature is raised to 1040-1120 DEG C at a rate of 10 DEG C / min, and the temperature is kept for 0-80 min, and then the sample is quickly placed in a 400 DEG C muffle furnace, and finally the sample is cooled to room temperature with the furnace. In this step, the heating rate directly affects the size and uniformity of the bubbles, and must be strictly controlled; in addition, the sample is placed in a 400 DEG C muffle furnace after the holding period ends in order to eliminate internal stress of the sample and improve the compressive strength.

[0019] A foamed ceramic is prepared by the preparation method of the foamed ceramic using lead smelting fuming residue as a raw material.

[0020] Advantages of the present application:

[0021] (1) The foamed ceramic with excellent performance is prepared by using lead smelting fuming residue as a main raw material in the present application, the doping amount of the residue is 70-75%, which ensures the large use of lead smelting fuming residue, reduces the influence of solid waste on the ecological environment, provides a new idea for the sustainable development of the lead smelting industry, realizes the full-component utilization of lead smelting fuming residue, and realizes substantial emission reduction.

[0022] (2) The foamed ceramic prepared in the present application has a bulk density of 757-202kg / m 3 , a compressive strength of 21.7-1.43MPa, an average pore size of 0.45-1.87mm, and a thermal conductivity of 0.4498-0.1100W / (m·K), and the bubble pore size is uniform, which can be used as a wall thermal insulation material (in accordance with GB / T33500-2017

External wall external insulation foamed ceramic

[0023] (3) The present application adopts a segmented cooling mode, which ensures the integrity of the internal pore structure and avoids defects (such as shown in Figure 7 ) generated during the solidification process, which is beneficial to improve the physical and chemical properties of the foamed ceramic.

[0024] (4) The present application adopts a one-step powder sintering method, by mixing the lead smelting fuming residue after iron removal with other additives, the raw material source is wide, the process is simple, the sintering period is short, the production cost is low, and the economic benefit is high.

[0025] (5) The preparation process of the present application generates the oxidation process of foaming agent AlN, AlN+O2=Al2O3+N2, which is the process of gas bubble formation and growth under a certain viscosity of high temperature melt. AlN foaming agent is selected because it not only produces N2, but also generates alumina products, which can also play a role in stabilizing bubbles, without the need to add a bubble stabilizer. Borax is used to reduce its melting temperature, which is a common fluxing agent. Quartz sand is of analytical purity, which aims to supplement silicon materials and does not introduce other impurities, so as to ensure the high utilization rate of the residue as much as possible.

[0026] (6) The foamed ceramic product prepared by the present application is composed of microcrystals and glass bodies, which have the effect of solidification and storage of toxic heavy metal ions, good chemical stability, and elimination of potential environmental risks. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The apparent structure diagram of the foamed ceramic prepared in Example 1 of the present application;

[0028] Figure 2 The apparent structure diagram of the foamed ceramic prepared in Example 2 of the present application;

[0029] Figure 3 The apparent structure diagram of the foamed ceramic prepared in Example 3 of the present application;

[0030] Figure 4 The apparent structure diagram of the foamed ceramic prepared in Example 4 of the present application;

[0031] Figure 5 The apparent structure diagram of the foamed ceramic prepared in Example 5 of the present application;

[0032] Figure 6 The apparent structure diagram of the foamed ceramic prepared in Example 6 of the present application;

[0033] Figure 7 The apparent structure diagram of the foamed ceramic prepared in Example 2 without annealing treatment of the present application;

[0034] Figure 8 The XRD diagram of the foamed ceramic prepared in Example 2 of the present application;

[0035] Figure 9 The apparent structure diagram of the foamed ceramic prepared in Example 7 of the present application;

[0036] Figure 10 The apparent structure diagram of the foamed ceramic prepared in Example 8 of the present application. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below with reference to the drawings and examples.

[0038] In the following examples, the thermal conductivity test adopts the guarded hot plate method for determination of steady-state thermal resistance and related properties of thermal insulating materials (GB / T 10294-2008); the bulk density test adopts the Archimedes drainage method; and the compressive strength test adopts the standard for testing the compressive strength of porous ceramics.

[0039] In the following examples, the raw material formula adopted is 75wt% lead smelting fuming slag after iron removal and 25wt% quartz sand; the specific component content (wt%) is SiO2 57.69%, CaO 21.11%, Al2O3 8.44%, MgO 2.17%, Na2O 2.57%, K2O 2.21%, FeO 0.45%, and other 5.36%.

[0040] In the following examples, the lead smelting fuming slag is dried, the drying temperature adopted is 105℃, the drying time is 24h, the grinding mode adopted is vibration grinding machine, the grinding time is 30-60s, and the screening size adopted is -200 mesh.

[0041] The residue composition of the lead smelting fuming slag after iron removal separation in the following examples is shown in Table 2.

[0042] Table 2 Chemical composition of the smelting residue (wt%)

[0043]

[0044] Example 1

[0045] A foamed ceramic taking lead smelting fuming slag as raw material and a preparation method thereof, comprising the following steps:

[0046] (1) The lead smelting fuming slag is dried, crushed, ground and screened, and 50g is taken for use;

[0047] (2) 7.021g of pulverized coal is added to the treated fuming slag in step (1) and uniformly mixed (carbon ratio 1.4), which is pressed into a cylindrical shape (φ15x55.5mm), the cylinder is loaded into a corundum crucible, and placed in a high-temperature furnace at 1200℃ for 60min, then taken out to obtain the reduction slag; the reduction slag is then placed in a graphite crucible, and placed in a high-temperature furnace at 1550℃ for 120min, then the temperature of the high-temperature furnace is reduced to 1450℃ for 150min, then taken out and rapidly water quenched, and the smelting residue and metallic iron are separated;

[0048] (3) the obtained melting residue is melted in a high temperature furnace, the melting temperature is 1450℃, the melting time is 150min, after the melting is completed, water quenching, drying, grinding, and sieving are performed to obtain a base glass powder;

[0049] (4) 25wt% quartz sand is added to the base glass powder, and mixing, grinding, and sieving are performed; then 6wt% borax and 0.6wt% AlN are added, and a planetary ball mill is used for ball milling, the rotation speed of the planetary ball mill is 230r / min, and the ball milling time is 150min;

[0050] (5) the obtained powder is loaded into a corundum crucible with a 1mm-thick refractory aluminum silicate paper laid on the inner wall and the bottom, after being laid flat and compacted, the volume of the powder accounts for about 50% of the volume of the corundum crucible, then the crucible is placed in a high temperature furnace, the temperature is increased from room temperature to 400℃ at a rate of 5℃ / min, and then the temperature is increased to 1040℃ at a rate of 10℃ / min, and the temperature is kept for 60min, after the keeping is completed, the crucible is quickly placed in a 400℃ muffle furnace, and finally the temperature is decreased to room temperature along with the furnace.

[0051] The apparent structure of the foamed ceramic prepared in Example 1 is shown in Figure 1 The foamed ceramic has small and uniform pores, the pore size distribution is concentrated, the pore size is between 0.2-0.6mm, and the average pore size is 0.45mm, and such a pore structure has a relatively high compressive strength.

[0052] Example 2

[0053] A foamed ceramic prepared by using lead smelting fuming slag as raw material and a preparation method thereof, comprising the following steps:

[0054] (1) the lead smelting fuming slag is dried, crushed, ground, and sieved; the sieving size is -200 mesh;

[0055] (2) powder coal is added to the fuming slag in step (1) and mixed (the carbon ratio is 1.4), and the mixture is pressed into a cylindrical shape (φ15x55.5mm), the cylinder is loaded into a corundum crucible, and is placed in a high temperature furnace at 1200℃ for 60min, then taken out to obtain reduced slag; the reduced slag is placed in a graphite crucible, and is placed in a high temperature furnace at 1550℃ for 120min, then the temperature of the high temperature furnace is decreased to 1450℃ for 150min, and then taken out and rapidly water quenched to separate the melting residue and metallic iron;

[0056] (3) the obtained melting residue is melted in a high temperature furnace, the melting temperature is 1450℃, the melting time is 150min, after the melting is completed, water quenching, drying, grinding, and sieving are performed to obtain a base glass powder;

[0057] (4) The base glass powder is mixed with 25wt% quartz sand, and then grinded, sieved; 6wt% borax and 0.6wt% AlN are added, and a planetary ball mill is used for ball milling, the rotation speed of the planetary ball mill is 230r / min, and the ball milling time is 150min;

[0058] (5) The obtained powder is loaded into a corundum crucible with a 1mm-thick refractory aluminum silicate paper laid on the inner wall and the bottom, and then is laid flat and compacted, the volume of the powder is about 50% of the volume of the corundum crucible, then the crucible is placed in a high-temperature furnace, and is heated from room temperature to 400℃ at a heating rate of 5℃ / min, and then is heated to 1120℃ at a heating rate of 10℃ / min, and is kept for 60min, and then is quickly placed in a 400℃ muffle furnace, and finally is cooled to room temperature along with the furnace.

[0059] The apparent structure of the foamed ceramic prepared in Example 2 is shown in Figure 2 The XRD pattern of the prepared lead smelting fuming residue glass-ceramics is shown in Figure 8 The foamed ceramic has moderate pore size and uniform pore diameter, the pore diameter distribution is concentrated, and the pore diameter is between 0.8-1.2mm, and the average pore diameter is 1.10mm, and such pore structure has excellent heat insulation performance.

[0060] Example 3

[0061] A foamed ceramic taking lead smelting fuming residue as raw material and a preparation method thereof, comprising the following steps:

[0062] (1) The lead smelting fuming residue is dried, crushed, grinded and sieved;

[0063] (2) The fuming residue in step (1) is mixed with pulverized coal (the carbon ratio is 1.4), and is pressed into a cylindrical shape (φ15×55.5mm), the cylinder is loaded into a corundum crucible, and is placed in a high-temperature furnace at 1200℃ for 60min, and then is taken out to obtain reduced residue; the reduced residue is placed in a graphite crucible, and is placed in a high-temperature furnace at 1550℃ for 120min, then the temperature of the high-temperature furnace is reduced to 1450℃ for 150min, and then is taken out and quickly water-quenched to separate the smelting residue and metallic iron;

[0064] (3) The obtained smelting residue is melted in a high-temperature furnace, the melting temperature is 1450℃, and the melting time is 150min, after the melting is completed, the smelting residue is water-quenched, dried, grinded, and sieved to obtain a base glass powder;

[0065] (4) The base glass powder is mixed with 25wt% quartz sand, and then grinded, sieved; 6wt% borax and 0.4wt% AlN are added, and a planetary ball mill is used for ball milling, the rotation speed of the planetary ball mill is 230r / min, and the ball milling time is 150min;

[0066] (5) The obtained powder was loaded into a corundum crucible with 1mm-thick refractory aluminum silicate paper on the inner wall and the bottom. After being flattened and compacted, the volume of the powder was about 50% of the volume of the corundum crucible. Then, the crucible was placed in a high-temperature furnace, and was heated from room temperature to 400℃ at a heating rate of 5℃ / min, and then was heated to 1120℃ at a heating rate of 10℃ / min, and was kept for 60min. After the end of the keeping, the crucible was quickly placed in a 400℃ muffle furnace, and was finally cooled to room temperature along with the furnace.

[0067] The apparent structure of the foamed ceramic prepared in Example 3 is shown in Figure 3 The foamed ceramic has small and non-uniform pores with a wide pore size distribution, the pore size is between 0.4-1.2mm, and the average pore size is 0.89mm. Such a pore structure reduces the compression resistance and heat insulation capacity of the foamed ceramic.

[0068] Example 4

[0069] A foamed ceramic prepared from lead smelting fuming slag and a preparation method thereof, comprising the following steps:

[0070] (1) The lead smelting fuming slag was dried, crushed, ground and sieved;

[0071] (2) The fuming slag in step (1) was mixed with pulverized coal (carbon ratio 1.4) and was pressed into a cylindrical shape (φ15x55.5mm). The cylinder was loaded into a corundum crucible and was placed in a high-temperature furnace at 1200℃ for 60min, and then was taken out to obtain reduced slag. The reduced slag was placed in a graphite crucible and was placed in a high-temperature furnace at 1550℃ for 120min. After that, the temperature of the high-temperature furnace was reduced to 1450℃ for 150min. After being taken out, the reduced slag was rapidly water-quenched to separate the smelting residue and metallic iron;

[0072] (3) The obtained smelting residue was melted in a high-temperature furnace at a melting temperature of 1450℃ for 150min. After the end of the melting, the smelting residue was water-quenched, dried, ground and sieved to obtain a base glass powder;

[0073] (4) 25wt% quartz sand was added to the base glass powder, and was mixed, ground and sieved. 6wt% borax and 1.0wt% AlN were added, and a planetary ball mill was used for ball milling at a rotation speed of 230r / min for 150min;

[0074] (5) The obtained powder is loaded into a corundum crucible with 1mm-thick refractory aluminum silicate paper on the inner wall and the bottom, and is flattened and compacted, and then the volume of the powder is about 50% of the volume of the corundum crucible, and then the crucible is placed in a high-temperature furnace, and is heated at a heating rate of 5℃ / min from room temperature to 400℃, and is kept at 400℃ for 20min, and then is heated at a heating rate of 10℃ / min to 1120℃, and is kept at 1120℃ for 60min, and then is quickly placed in a muffle furnace at 400℃, and finally is cooled to room temperature along with the furnace.

[0075] The apparent structure of the foamed ceramic prepared in Example 4 is shown in Figure 4 The foamed ceramic has coarse and interconnected pores, and the pore size distribution is wide, and the average pore size is 1.87mm, and the compressive strength of the foamed ceramic with such a pore structure is poor.

[0076] Example 5

[0077] A foamed ceramic prepared from lead smelting fuming slag and a preparation method thereof, comprising the following steps:

[0078] (1) The lead smelting fuming slag is dried, crushed, ground and sieved;

[0079] (2) The fuming slag in step (1) is mixed with pulverized coal (carbon ratio 1.4) and is pressed into a cylindrical shape (φ15x55.5mm), and then the cylinder is loaded into a corundum crucible and is placed in a high-temperature furnace at 1200℃ for 60min, and then is taken out to obtain reduced slag; and then the reduced slag is placed in a graphite crucible and is placed in a high-temperature furnace at 1550℃ for 120min, and then the temperature of the high-temperature furnace is reduced to 1450℃ for 150min, and then is taken out and is quickly water-quenched to separate the smelting residue and metallic iron;

[0080] (3) The obtained smelting residue is melted in a high-temperature furnace, and the melting temperature is 1450℃ and the melting time is 150min, and then the melting is finished, and the smelting residue is water-quenched, dried, ground and sieved to obtain a base glass powder;

[0081] (4) The base glass is dried, and 25wt% quartz sand is added and is mixed, ground and sieved; 6wt% borax and 0.6wt% AlN are added, and a planetary ball mill is used for ball milling, and the rotation speed of the planetary ball mill is 230r / min and the ball milling time is 150min;

[0082] (5) The obtained powder is loaded into a corundum crucible with 1mm-thick refractory aluminum silicate paper on the inner wall and the bottom, and after being flattened and compacted, the volume of the powder is about 50% of the volume of the corundum crucible, then the crucible is placed in a high-temperature furnace, and the temperature is raised from room temperature to 400°C at a rate of 5°C / min, and then the temperature is raised to 1120°C at a rate of 10°C / min, and the temperature is kept for 20min, and after the end of the temperature keeping, the crucible is quickly placed in a 400°C muffle furnace, and finally the furnace is cooled to room temperature.

[0083] The apparent structure of the foamed ceramic prepared in Example 5 is shown in Figure 5 The foamed ceramic has fine and uniform pores with a pore size distribution concentrated between 0.6-0.9mm, and an average pore size of 0.88mm. Such a pore structure has a relatively high compressive strength, but a poor heat insulation capacity.

[0084] Example 6

[0085] A foamed ceramic using lead smelting fuming slag as raw material and a preparation method thereof, comprising the following steps:

[0086] (1) The lead smelting fuming slag is dried, crushed, ground and sieved;

[0087] (2) The fuming slag in step (1) is mixed with pulverized coal (carbon ratio 1.4) and pressed into a cylindrical shape (φ15x55.5mm), and the cylinder is loaded into a corundum crucible and placed in a high-temperature furnace at 1200°C for 60min, then taken out to obtain a reduction slag; the reduction slag is then placed in a graphite crucible and placed in a high-temperature furnace at 1550°C for 120min, then the temperature of the high-temperature furnace is lowered to 1450°C for 150min, and then taken out and rapidly water-quenched to separate the smelting residue and metallic iron;

[0088] (3) The obtained smelting residue is melted in a high-temperature furnace at a melting temperature of 1450°C for 150min, and after the melting is completed, the smelting residue is water-quenched, dried, ground and sieved to obtain a base glass powder;

[0089] (4) 25wt% quartz sand is added to the base glass powder, mixed, ground and sieved; 6wt% borax and 0.6wt% AlN are added, and a planetary ball mill is used for ball milling at a speed of 230r / min for 150min;

[0090] (5) The obtained powder is loaded into an alumina crucible with a refractory aluminum silicate paper of 1 mm thickness on the inner wall and bottom. After being spread and compacted, the volume of the powder accounts for about 50% of the volume of the alumina crucible. Then the crucible is placed in a high-temperature furnace and heated from room temperature to 400°C at a heating rate of 5°C / min and held for 20 min. Then the temperature is increased to 1120°C at a heating rate of 10°C / min and held for 80 min. After the holding period, the crucible is quickly placed in a muffle furnace at 400°C and finally cooled to room temperature with the furnace.

[0091] The apparent structure of the foamed ceramic prepared in Example 6 is as follows: Figure 6 As shown, the foamed ceramic has large and highly uneven pores with many interconnected pores. The pore size is mainly distributed between 0.5-2.0 mm, with an average pore size of 1.46 mm. This pore structure reduces the compressive strength and thermal insulation performance of the foamed ceramic.

[0092] Example 7

[0093] A foamed ceramic using lead smelting slag as raw material and its preparation method, comprising the following steps:

[0094] (1) Dry, crush, grind and sieve the lead smelting fumes, and take 50g for later use;

[0095] (2) Add 4.012g of pulverized coal to the fumed slag treated in step (1) and mix well (carbon ratio 1.4). Press it into a cylindrical shape (φ15×55.5mm). Place the cylinder into a corundum crucible and keep it in a high-temperature furnace at 1200℃ for 60min. Remove it to obtain the reduction slag. Then put the reduction slag into a graphite crucible and melt it in a high-temperature furnace at 1550℃ for 120min. Then lower the temperature of the high-temperature furnace to 1450℃ and keep it for 150min. Remove it and quickly quench it with water to separate the melt residue and metallic iron.

[0096] (3) The obtained molten residue is melted in a high-temperature furnace at a temperature of 1450℃ for 150 min. After melting, it is quenched in water, dried, ground, and sieved to obtain basic glass powder.

[0097] (4) Add 25wt% quartz sand to the base glass powder, mix, grind and sieve; then add 6wt% borax and 0.6wt% AlN, and ball mill using a planetary ball mill. The rotation speed of the planetary ball mill is 230r / min and the ball milling time is 150min.

[0098] (5) The obtained powder is loaded into a corundum crucible with 1mm-thick refractory aluminum silicate paper on the inner wall and the bottom, and after being flattened and compacted, the volume of the powder is about 50% of the volume of the corundum crucible, then the crucible is placed in a high-temperature furnace, and the temperature is raised from room temperature to 400℃ at a rate of 5℃ / min, and then the temperature is raised to 1140℃ at a rate of 10℃ / min, and the temperature is kept for 60min, and after the end of the temperature keeping, the crucible is quickly placed in a 400℃ muffle furnace, and finally the furnace is cooled to room temperature.

[0099] The apparent structure of the foamed ceramic prepared in Example 7 is shown in Figure 9 The foamed ceramic has coarse pores and many connected pores, the pore size is distributed between 0.4-1.6mm, and the average pore size is 1.13mm, which destroys the compression resistance of the foamed ceramic.

[0100] Example 8

[0101] A foamed ceramic using lead smelting fuming slag as raw material and a preparation method thereof, comprising the following steps:

[0102] (1) The lead smelting fuming slag is dried, crushed, ground and sieved, and 50g is taken for use;

[0103] (2) 9.027g of pulverized coal is added to the treated fuming slag in step (1) and mixed uniformly (carbon ratio 1.4), and then pressed into a cylindrical shape (φ15x55.5mm), and the cylinder is loaded into a corundum crucible and placed in a high-temperature furnace at 1200℃ for 60min, then taken out to obtain reduced slag; the reduced slag is then placed in a graphite crucible and placed in a high-temperature furnace at 1550℃ for 120min, then the temperature of the high-temperature furnace is lowered to 1450℃ for 150min, and then taken out and rapidly water-quenched to separate the smelting residue and metallic iron;

[0104] (3) The obtained smelting residue is melted in a high-temperature furnace, the melting temperature is 1450℃, and the melting time is 150min, after the end of melting, water-quenching, drying, grinding and sieving, the base glass powder is obtained;

[0105] (4) 25wt% of quartz sand is added to the base glass powder, mixed, ground and sieved; then 6wt% of borax and 0.2wt% of AlN are added, and a planetary ball mill is used for ball milling, the rotation speed of the planetary ball mill is 230r / min, and the ball milling time is 150min;

[0106] (5) The obtained powder is charged into a corundum crucible with inner wall and bottom lined with 1 mm thick refractory aluminum silicate paper, and after being flattened and compacted, the volume of the powder is about 50% of the volume of the corundum crucible, then the crucible is placed in a high temperature furnace, and heated from room temperature to 400°C at a heating rate of 5°C / min, and kept for 20 min, then heated to 1120°C at a heating rate of 10°C / min, and kept for 60 min, after the end of the keeping, it is quickly placed in a muffle furnace at 400°C, and finally cooled to room temperature with the furnace.

[0107] The apparent structure of the foamed ceramic prepared in Example 8 is shown in Fig. 8. The foamed ceramic has small and dense cells, and the cell diameter is unevenly distributed between 0.6-1.8 mm, and the average cell diameter is 1.35 mm. Although this cell structure has high compressive strength, the heat insulation capacity is poor. Figure 10 The apparent structure of the foamed ceramic prepared in Example 8 is shown in Fig. 8. The foamed ceramic has small and dense cells, and the cell diameter is unevenly distributed between 0.6-1.8 mm, and the average cell diameter is 1.35 mm. Although this cell structure has high compressive strength, the heat insulation capacity is poor.

[0108] Figures 1-8 The apparent structure of the foamed ceramic prepared in Example 8 is shown in Fig. 8. The foamed ceramic has small and dense cells, and the cell diameter is unevenly distributed between 0.6-1.8 mm, and the average cell diameter is 1.35 mm. Although this cell structure has high compressive strength, the heat insulation capacity is poor.

[0109] Table 3 Performance test table of foamed ceramic

[0110]

[0111] ​

Claims

1. A method for preparing foamed ceramics using lead smelting slag as raw material, characterized in that, Includes the following steps: (1) Dry, grind and sieve the lead smelting slag, and store it for later use; (2) The treated lead smelting slag is thoroughly mixed with pulverized coal, and the reaction is carried out according to the carbon ratio of 0.8-1.8, the reduction temperature and the reduction time. After the reaction is completed, the temperature is raised to the melting temperature and kept at that temperature. After the temperature is kept at that temperature, the furnace is cooled to room temperature and the metallic iron and the melting residue are separated. (3) The obtained molten residue is melted in a high-temperature furnace. After melting, it is quenched in water, dried, ground, and sieved to obtain basic glass powder, which is used as raw material for preparing foamed ceramics. (4) Add auxiliary materials, flux, and foaming agent to the base glass powder obtained in step (3), and ball mill the mixture; the auxiliary material is 25-30 wt% quartz sand, the flux is 6 wt% borax, and the foaming agent is 0.2-1.2 wt% AlN; (5) The ball-milled powder is loaded into a corundum crucible, spread and compacted, and placed in a high-temperature furnace for firing according to a certain heat treatment regime. The specific steps are as follows: the ball-milled powder is loaded into a corundum crucible with refractory aluminum silicate paper of 1 mm thickness on the inner wall and bottom. After spreading and compacting, the volume of the powder accounts for 50% of the volume of the corundum crucible. The crucible is placed in a high-temperature furnace and heated from room temperature to 400℃ at a heating rate of 5℃ / min and held for 20 min. Then, the temperature is raised to 1040-1120℃ at a heating rate of 10℃ / min and held for 20-80 min. After the holding period, the crucible is quickly placed in a muffle furnace at 400℃ and cooled to room temperature with the furnace.

2. The method for preparing foamed ceramics using lead smelting slag as raw material according to claim 1, characterized in that, In step (2), the reduction temperature is 900-1400℃ and the reduction time is 20-100min; the melting temperature is 1500-1600℃ and the holding time is 100-130min.

3. The method for preparing foamed ceramics using lead smelting slag as raw material according to claim 1, characterized in that, In step (3), the melting temperature is 1450-1500℃ and the melting time is 150-180min.

4. A foamed ceramic, characterized in that, It is prepared by the preparation method according to any one of claims 1-3.

5. A foamed ceramic according to claim 4, characterized in that, The bulk density of the foamed ceramic is 757-202 kg / m³. 3 It has a compressive strength of 21.7-1.43 MPa, an average pore size of 0.45-1.87 mm, and a thermal conductivity of 0.4498-0.1100 W / (m·K).

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