Method for producing aluminum silicon carbide brick by using waste refractory materials

In recent years, mineral resources have been controlled and restricted by national environmental protection policies, and the prices of refractory raw materials have been increasing.
From the perspective of refractory resources, China's refractory raw material reserves have decreased. Shanxi Yangquan, with a bauxite reserve of 120 million tons, has been exploited for nearly a hundred years, and the better-grade bauxite deposits are on the verge of exhaustion. The scorched gemstones of Shandong Province, which were famous all over the world at the time, have been closed for production and bankruptcy and reorganization in the 1990s due to the large amount of mining and the age. In addition, after long-term mining of magnesia refractory raw material deposits, the main mine and concentrate areas are gradually reduced, and some have now switched from open-pit mining to underground mining. In addition, the small mines and corner mines that are wasted due to irregular mining are increasing every year, causing a serious waste of resources. Facing the phenomenon of declining mineral resources and serious waste of resources, saving resources and comprehensive utilization of resources have become an urgent task.
In the prior art, the disposal of waste refractory materials is mainly landfill, which not only occupies the land, the waste refractory materials after weathering and rain can easily cause soil and soil damage, and some waste refractory materials can cause cancer (such as chromium-containing refractories). Materials), radioactive (such as refractory materials containing zirconium). With the advancement of China's recycling economy and sustainable development strategy, the research and reuse of waste refractory materials after use also need to gradually increase, and develop in the direction of high technology and high technology added value. Therefore, the comprehensive utilization of refractory resources to maximize the effect of limited resources and achieve sustainable development is the need of social development and is a necessity.

Aiming at the problems of the existing technology, this article aims to provide a way to save resources and improve environmental protection.
Method for producing aluminum silicon carbide bricks from refractory materials.
1. Material selection: use waste high alumina bricks for blast furnaces, waste silicon carbide slabs in the ceramic industry, soft mud and waste first-class high alumina bricks that meet the requirements;
2. Crushing: Put the above-mentioned raw materials into a roller machine for crushing, and pass the particles crushed out of the roller machine through a 6-mesh vibrating screen. The particle size requirement is that the particle size> 5mm should be less than or equal to 10% of all particles. Particles <0.5mm should be less than or equal to 20% of all particles;
3. Iron removal from crushed powder: After the bulk material is crushed and sieved, permanent magnets should be installed on the chute and lower powder trough of the belt conveyor to remove iron. Iron is required to be taken every 20 minutes;
4. Grinding powder: Use Raymond mill to grind fine powder. It must be fed evenly, and the feeding speed and fan speed must be controlled, and the horizontal sieve speed must be adjusted. The powder particle size should reach ≤ 0.088mm and ≥ 90% of the powder;
5. Ingredients: Calibrate the scales before ingredients, and the weighing error of various raw materials shall not exceed 3%;
6. Proportion: The weight percentage of each component and composition is 30% of 6 mesh first grade alumina, 30% of 6 mesh waste high alumina brick, 12% silicon carbide plate fine powder, 180 mesh fine alumina powder 23%, 180 mesh Soft clay powder 5%, wood calcium liquid 4% ~ 4.5%;
7. Mixing and grinding: first add various aggregate particles into the planetary mixer, while mixing and grinding, add wood calcium solution to moisten the particles, and then add fine powder, and the mixing time is not less than 10 minutes;
8. Forming: A 400-ton friction brick press is used for forming, and the bulk density of the bricks is controlled to 2.9g/cm3;
9. Inspection: The porosity of the brick blank should be ≤ 19%; the error of the size ≤ 200mm is ±1mm, the error of the size ≥ 200mm is ±2mm; the distortion is ≤ 0.5mm; the relative deviation of the same size should be ≤ 1.0mm; the depth of the missing edge ≤ 3.0mm , The length is ≤ 60mm, the depth of the missing corner is ≤ 3.0mm; the flash should be smoothed and the thickness should be ≤ 1.0mm; cracks, spalling and pockmarked surfaces are not allowed;
10. Drying: Take the natural drying method. The drying site should be level. Spread quartz sand with a thickness of> 10mm on it and scrape it smoothly. The yard bricks must be handled lightly. The height of the yard bricks should not exceed 1.2m. Wait until the bricks have residual moisture ≤ 2% can be installed in the kiln;
11. Kiln installation: the side-mounted kiln method is adopted, so that the side is dense and the upper is dense and the lower is thin. The distance between each brick stack is 80-100mm, and the distance between the brick stack and the side of the kiln is 150-200mm. The distance is 100~150mm; the distance between the bricks on the top of the kiln is 15~20mm, the upper part is 20~25mm, and the lower part is 25~30mm; and the bricks are required to be sprinkled with scorched gem powder with a particle size of ≤ 2mm and smoothed. Sprinkle the chaff hulls between the bricks and the green bricks to prevent the bricks from sticking; leave a fire channel facing the center line of the kiln door, with a height of 0.8 ~ 1.0m, and a temperature measuring cone should be placed at a distance of 1.2 ~ 1.4m from 2 kiln doors. One; the kiln door is enclosed in two layers inside and outside, leaving a gap of about 100mm in the middle for heat insulation, and leaving an observation temperature measuring hole facing the fire channel;
12. Firing: From ignition to heating to 1500℃ in the kiln, the cumulative time is usually 123 hours; frequently observe the temperature in the kiln, and keep warm after the fire cone is bent, and stop the fire after 8 hours of keeping warm; Put down all the flue gates half an hour after the fire;
13. Heat dissipation and cooling: 16 hours after the fire is braked, open the kiln top radiating holes, open the outer kiln door, open 1/3 of the kiln door after 24 hours, open all the kiln doors after 40 hours, lift the flue gate, and open the fire box Cover plate, blast cooling to room temperature;

Points to note:
1. Selection of waste refractory materials: use waste and waste silicon carbide slabs used in the ceramic industry to remove iron nodules, coal fusion nodules, limestone and underburned materials and other impurities;
2. Picking of box sand: It is required to be of good quality, and there should be no fragments such as tiles;
3. The selection of soft mud: it requires few impurities, pure quality, and good clay;
4. Picking of first-class high-alumina bricks: pure quality and high bulk density are required, and low-grade waste bricks and impurities need to be selected and removed.
5. The speed of the horizontal screen in step 4 shall not be less than 600 rpm.
6. In step 9, it is required to operate according to the method of lightening first and then slowly raising the head.
7. Step 7: The particle size and moisture requirements of the mud during mixing are as follows: particle size> 5mm, moisture requirement ≤ 10%; particle size 5 ~ 3mm, moisture requirement 20 ~ 30%; particle size 3 ~ 1mm, moisture requirement 20 ~30%; particle size≤0.1mm, moisture requirement is 35~45%; mud moisture content is 5.0~5.5%.
8. Step 7: The specific gravity of the calcium lignosulfonate solution in the mixed mill is 1.18 ~ 1.25g/cm3.
9. Step 12 Firing includes: ignition-heating up to 200°C: heating rate is 5°C/hour, which takes 36 hours; 200°C heat preservation for 12 hours; 200-800°C: heating rate is 25°C/hour, which takes 24 hours; 800 ~ 1200℃: the heating rate is 20℃/hour, it takes 20 hours; 1200 ~ 1400℃: the heating rate is 15℃/hour, it takes 13 hours; 1400 ~ 1500℃: the heating rate is 10℃/hour, it takes 10 hours ; Keep at 1500℃ for 8 hours.

The method of using waste refractory materials to produce aluminum silicon carbide bricks provided in this article not only solves the problem of landfill occupied by waste refractory materials, saves resources, but also improves the environment. At the same time, it treats radioactive or carcinogenic items that have undergone weathering and rain. Damage to the soil quality.