A method for producing anti-seepage bricks for aluminum electrolytic cells from waste electrical porcelain materials

Abstract

This invention relates to a method for producing anti-seepage bricks for aluminum electrolysis cells from waste electrical porcelain materials, comprising the following steps: 1) The waste electrical porcelain materials are coarsely crushed to below 50mm using a jaw crusher, then medium crushed to below 10mm using a double roll crusher, and finally finely crushed to below 2.8mm using a double roll crusher to obtain waste electrical porcelain aggregate ≤2.8mm; 2) The waste electrical porcelain aggregate is mixed with a binder and a component modifier to obtain a mud, which is then subjected to a binding treatment, pressed into a green body, dried, and fired at high temperature to obtain anti-seepage bricks for aluminum electrolysis cells; In step 1), the material after medium crushing is screened and graded to obtain coarse particles of 10-6mm, medium particles of 6-3mm, and fine particles ≤3mm. The coarse, medium, and fine particles are then mixed in a ratio of 1:1:1-1.5 and further finely crushed. This invention, by controlling the quality of the aggregate after crushing the waste electrical porcelain materials, can increase the green body appearance qualification rate to over 96%.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to a method for producing anti-seepage bricks for aluminum electrolytic cells from waste electrical porcelain materials. Background Technology

[0002] In the power industry, replacing various electrical insulation components generates a large amount of waste electrical porcelain, posing challenges in its storage and disposal. Using waste electrical porcelain materials to produce anti-seepage bricks for aluminum electrolysis cells can achieve the recycling of waste resources, reduce the production cost of anti-seepage bricks, and play a role in energy conservation and environmental protection.

[0003] Traditional aluminum galvanized cell seepage-proof bricks are produced using coke-derived gemstone as aggregate. This aggregate is mixed with other raw materials to prepare slurry, which is then pressed into green bodies. The green body appearance qualification rate is generally above 98%. However, waste electrical porcelain materials differ in properties from coke-derived gemstone. When using waste electrical porcelain materials to produce aluminum galvanized cell seepage-proof bricks, the green body appearance qualification rate decreases significantly. While conditioning the slurry can improve the green body appearance qualification rate, it remains below normal levels and fluctuates considerably. Summary of the Invention

[0004] To improve the green body qualification rate of aluminum electrolytic cell anti-seepage bricks produced from waste electrical porcelain materials, this invention provides a method for producing aluminum electrolytic cell anti-seepage bricks from waste electrical porcelain materials. The specific scheme is as follows:

[0005] A method for producing anti-seepage bricks for aluminum electrolytic cells from waste electrical porcelain materials includes the following steps:

[0006] 1) Waste electrical porcelain material is coarsely crushed to below 50mm by a jaw crusher, then medium crushed to below 10mm by a double roll crusher, and then finely crushed to below 2.8mm by a double roll crusher to obtain waste electrical porcelain aggregate with a diameter of ≤2.8mm.

[0007] 2) Waste electrical porcelain aggregate is mixed with binder and component modifier to obtain mud. The mud is then subjected to a binding treatment and then pressed to obtain green body. After the green body is dried, it is fired at high temperature to obtain aluminum electrolytic cell seepage-proof brick.

[0008] In step 1), the material after medium crushing is screened and classified to obtain coarse material of 10-6mm, medium material of 6-3mm and fine material of ≤3mm. The coarse material, medium material and fine material are mixed in a ratio of 1:1:1-1.5 and then finely crushed.

[0009] In step 2), the binder includes clay and dextrin, and the component modifier is sepiolite powder.

[0010] The phase composition of waste electrical porcelain materials includes mullite crystalline phase and glass phase. The glass phase is a continuous phase, with mullite crystals of micron size dispersed in the glass phase. After crushing, the particle surface is smooth, but the particle shape is poor, with more flaky particles. The plasticity of the clay is poor, and the bonding strength between particles is poor when preparing the clay. This is the main reason for the reduced appearance qualification rate when pressing green bodies. It is mainly manifested in appearance defects such as cracks and chipped edges after the green bodies are demolded.

[0011] This solution improves the crushing process of waste electrical porcelain materials, thereby enhancing the quality of the aggregate after crushing and increasing the appearance qualification rate of pressed green bodies.

[0012] Furthermore, in step 1), the coarse, medium, and fine particles are mixed in a ratio of 1:1:1.5 and then finely crushed.

[0013] Furthermore, in step 1), after the material is screened and graded following the medium crushing, when the proportion of coarse material is greater than 60%, the gap of the double roll crusher in the medium crushing is reduced.

[0014] Furthermore, in step 1), during fine crushing, the speed ratio of the moving roller and the stationary roller in the roller crusher is 1:1.5. Using differential speed operation is beneficial to improving aggregate quality.

[0015] Furthermore, in step 1), during fine crushing, the feed hopper of the double roll crusher is equipped with two longitudinal partitions. The width direction of the partitions is consistent with the axial direction of the double rolls. The partitions divide the feed hopper into three material chambers. During feeding, coarse material enters the material chamber near the fixed roll, medium material enters the middle material chamber, and fine material enters the material chamber near the moving roll.

[0016] Furthermore, when there is insufficient fine material, a portion of the finely crushed material is returned to the fine material as supplementary material.

[0017] Furthermore, the bulk density of the finely crushed material is tested. If the bulk density is less than 1.25 g / cm3, the proportion of recycled material is increased.

[0018] The quality of waste electrical porcelain aggregate particles can be reflected by changes in bulk density. When the particle shape is relatively regular, with fewer flaky particles and the particles are close to spherical, the bulk density is higher, and vice versa.

[0019] Furthermore, the finely crushed material enters the storage silo through a feed chute. A sampling tube is connected to the feed chute, and the material flow rate of the sampling tube is not less than 100 g / s. An inclined rotating drum is installed at the discharge end of the sampling tube. The feed end of the rotating drum is equipped with an outer baffle ring and an inner baffle ring, with a distance of 10 cm between the outer and inner baffle rings. The diameter of the rotating drum is not greater than 20 cm, the height of the outer baffle ring is not greater than 4 cm, the inner baffle ring is higher than the outer baffle ring, and the inner baffle ring has a notch. The rotating drum is equipped with a rotating support, and the rotating support is equipped with a weight sensor. The rotation speed of the rotating drum is 2 r / min. The detection value of the weight sensor is used to evaluate the bulk density of the finely crushed material.

[0020] This invention can improve the green body appearance qualification rate to over 96% by controlling the aggregate quality after crushing waste electrical porcelain materials. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the fine crushing feed hopper in Example 6.

[0022] Figure 2 This is a schematic diagram of the rotating drum in Example 7. Detailed Implementation

[0023] The present invention will now be clearly described in conjunction with specific embodiments. This description is merely illustrative and is not intended to limit the scope of the invention. Any modifications, equivalent substitutions, or improvements made by those skilled in the art based on the embodiments of the present invention without inventive effort to obtain all other embodiments should be included within the scope of protection of the present invention.

[0024] Example 1

[0025] 1) Waste electrical porcelain material is coarsely crushed to below 50mm by a jaw crusher, then medium crushed to below 10mm by a double roll crusher, and then finely crushed to below 2.8mm by a double roll crusher to obtain waste electrical porcelain aggregate with a diameter of ≤2.8mm.

[0026] 2) First, mix the solid binder (soft clay, 30 wt% of the waste electrical porcelain aggregate) and the composition modifier (sepiolite powder, 20 wt% of the solid binder) into a mixed powder. Mix the liquid binder (30 wt% dextrin, 3 wt% of the total solids) with the waste electrical porcelain aggregate for 8 minutes. Then add the mixed powder and continue stirring for 25 minutes to obtain mud. Let the mud rest for 24 hours.

[0027] 3) The clay material after being cured was pressed into green blanks using a molding machine. 100 blanks were formed, and the appearance qualification rate was 92%.

[0028] 4) After the green body is dried, it is placed in a high-temperature pusher kiln for high-temperature firing at 1200℃.

[0029] Example 2

[0030] Based on Example 1, to improve crushing efficiency, the material after medium crushing is pre-screened to separate materials ≤2.8mm. This portion of material does not undergo fine crushing and directly enters the raw material silo as aggregate, while materials larger than 2.8mm enter the fine crushing process. After the process change, the crushing efficiency is significantly improved, but the green body qualification rate during molding is only 88%.

[0031] Analysis of samples of ≤2.8mm material from the secondary crushing process revealed that this material was mostly flaky and unsuitable for direct use as aggregate. Further analysis showed that in the fine crushing stage, in addition to crushing, there is also grinding between particles. The secondary crushing stage has a larger crushing ratio (reaching 5), resulting in more pronounced crushing and thus producing more flaky particles. In the fine crushing stage, the crushing ratio is below 4, leading to more grinding between particles and producing more regular-shaped particles. This grinding also reduces the smoothness of the particle cross-section, which is beneficial for improving aggregate quality.

[0032] Examples 3-5 are used to compare the effect of particle size distribution on finely crushed materials.

[0033] Example 3

[0034] The material after medium crushing is screened and classified to obtain coarse particles of 10-6mm, medium particles of 6-3mm, and fine particles of ≤3mm. The coarse, medium, and fine particles are then mixed in a 1:1:1 ratio and further crushed. The remaining steps are the same as in Example 1. The green body qualification rate during molding is 93%.

[0035] Example 4

[0036] The material after medium crushing is screened and classified to obtain coarse particles of 10-6mm, medium particles of 6-3mm, and fine particles of ≤3mm. The coarse, medium, and fine particles are then mixed in a ratio of 1:1:1.3 and further crushed. The remaining steps are the same as in Example 1. The green body qualification rate during molding is 93%.

[0037] Example 5

[0038] The material after medium crushing is screened and classified to obtain coarse particles of 10-6mm, medium particles of 6-3mm, and fine particles of ≤3mm. The coarse, medium, and fine particles are then mixed in a ratio of 1:1:1.5 and further crushed. The remaining steps are the same as in Example 1. The green body qualification rate during molding is 95%.

[0039] In actual production, after medium crushing, the material is screened and fed into different bins according to particle size. The mass ratio of coarse material is over 40%, and an excessively high proportion of fine material can easily lead to raw material imbalance. This problem can be solved to some extent by reducing the gap of the roller crusher during medium crushing to increase the crushing ratio, or by using a portion of the finely crushed material as return material to supplement the fine material.

[0040] By controlling the particle size distribution of materials before fine crushing, the quality of aggregates after fine crushing can be improved, and the problem of raw material fluctuations can be solved, thereby improving the stability of aggregate quality.

[0041] Example 6

[0042] Considering the influence of the particle size distribution of the material before fine crushing on the crushing and grinding effects during fine crushing, the moving and stationary rollers operate at different speeds during fine crushing, with a speed ratio of 1:1.5. Because the moving and stationary rollers of the double-roll crusher operate at different speeds during fine crushing, the stationary roller rotates at a higher speed, resulting in a greater crushing effect on the side closer to the stationary roller and a greater grinding effect on the side closer to the moving roller. For example... Figure 1 This embodiment improves the fine crushing feeding method by dividing the feed hopper 1 into three material chambers using a partition 2. Materials of different particle sizes enter different material chambers through the feed chute. During feeding, coarse particles enter the material chamber closest to the stationary roller 3, medium particles enter the middle material chamber, and fine particles enter the material chamber closest to the moving roller 4. After the improvement, the green body appearance qualification rate is increased to 96%.

[0043] Samples were taken from the impermeable bricks fired in Examples 1-6 and tested. The results are as follows:

[0044]

[0045] Example 7

[0046] While visual inspection of aggregate particle shape can qualitatively assess aggregate quality, it cannot establish a quantitative standard. Considering that particle shape affects the density of particle packing, when the properties of the raw material itself (bulk density of the porcelain raw material) remain unchanged, the bulk density of the bulk material can be used to quantitatively evaluate aggregate quality.

[0047] The bulk density of the finely crushed aggregates from Examples 1-6 was measured, and the results are shown in the table below:

[0048]

[0049] The method for testing the bulk density of bulk materials is as follows: A vibrating feeder is used to uniformly feed the material, which is then collected in a 100ml measuring cup. After the material overflows, a scraper is used to level the top of the measuring cup, and the material is then weighed to calculate the bulk density. It can be seen that there is a corresponding relationship between the bulk density and the appearance qualification rate during green compact pressing.

[0050] This embodiment also designs a device for online evaluation of aggregate bulk density, such as... Figure 2 As shown, the finely crushed material enters the storage silo through a feed chute. A sampling pipe 5 is connected to the feed chute, with a material flow rate of not less than 100 g / s. An inclined rotating drum 10 is installed at the discharge end of the sampling pipe. The feed end of the drum has an outer baffle ring 6 and an inner baffle ring 7, with a distance of 10 cm between them. The diameter of the drum is not greater than 40 cm, the height of the outer baffle ring is not greater than 4 cm, and the inner baffle ring is higher than the outer baffle ring. The inner baffle ring has a notch. The drum has a rotating support 8, and a weight sensor 9 is installed on the rotating support. The rotation speed of the drum is 2 r / min. The space between the outer and inner baffle rings can be used as a constant-volume space. Each time the drum rotates, the volume of the feed material is greater than the volume of the constant-volume space. Excess material overflows along the outer baffle ring, while material entering the constant-volume space flows into the drum through the notch in the inner baffle ring. During stable operation, the volume of material contained in the drum is constant, and the value detected by the weight sensor can evaluate the bulk density of the finely crushed material.

Claims

1. A method for producing anti-seepage bricks for aluminum electrolytic cells from waste electrical porcelain materials, characterized in that, Includes the following steps: 1) Waste electrical porcelain material is coarsely crushed to below 50mm by a jaw crusher, then medium crushed to below 10mm by a double roll crusher. The material after medium crushing is screened and classified to obtain coarse material of 10-6mm, medium material of 6-3mm, and fine material of ≤3mm. The coarse, medium, and fine materials are mixed in a ratio of 1:1:1.5 and then finely crushed to below 2.8mm by a double roll crusher to obtain waste electrical porcelain aggregate of ≤2.8mm. During fine crushing, the feed hopper of the double roll crusher is equipped with two longitudinal baffles. The width of the baffles is consistent with the axial direction of the double rolls. The baffles divide the feed hopper into three material chambers. During feeding, coarse material enters the material chamber closest to the fixed roll, medium material enters the middle material chamber, and fine material enters the material chamber closest to the moving roll. 2) Waste electrical porcelain aggregate is mixed with binder and component modifier to obtain mud material. The component modifier is sepiolite powder. The mud material is subjected to bridging treatment, then pressed to obtain green body. After the green body is dried, it is fired at high temperature to obtain aluminum electrolytic cell seepage-proof brick. In step 1), during fine crushing, the speed ratio of the moving roller and the stationary roller in the roller crusher is 1:1.

5.

2. The method for producing anti-seepage bricks for aluminum electrolytic cells from waste electrical porcelain materials according to claim 1, characterized in that: In step 1), after the material is screened and graded after medium crushing, when the proportion of coarse material is greater than 60%, the gap of the double roll crusher for medium crushing is reduced.

3. The method for producing anti-seepage bricks for aluminum electrolytic cells from waste electrical porcelain materials according to claim 1, characterized in that: When there is insufficient fine material, some of the finely crushed material is returned to the fine material as supplementary material.

4. The method for producing anti-seepage bricks for aluminum electrolytic cells from waste electrical porcelain materials according to claim 3, characterized in that: The bulk density of the finely crushed material was tested, and the bulk density was less than 1.25 g / cm³. 3 At the same time, increase the proportion of returned materials.

5. The method for producing anti-seepage bricks for aluminum electrolytic cells from waste electrical porcelain materials according to claim 4, characterized in that: The crushed material enters the storage silo through a feed chute. A sampling tube is connected to the feed chute, and the material flow rate of the sampling tube is not less than 100 g / s. An inclined rotating drum is installed at the discharge end of the sampling tube. The feed end of the rotating drum is equipped with an outer baffle ring and an inner baffle ring, with a distance of 10 cm between the outer and inner baffle rings. The diameter of the rotating drum is not greater than 20 cm, the height of the outer baffle ring is not greater than 4 cm, the inner baffle ring is higher than the outer baffle ring, and the inner baffle ring has a notch. The rotating drum is equipped with a rotating support, and the rotating support is equipped with a weight sensor. The rotation speed of the rotating drum is 2 r / min. The detection value of the weight sensor is used to evaluate the bulk density of the crushed material.

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