The Problems and Improvements in the Application of DI-type Mobile Vacuum Filter in Alumina Production

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The Problems and Improvements in the Application of DI-type Mobile Vacuum Filter in Alumina Production
Core Tip: Non-ferrous metals DI type mobile chamber belt vacuum filter in the alumina production and application of existing problems and their improvement measures exist in the application of 6789 it; Jincai China Aluminum Shanxi Branch He Zhengmin Cao Junling Dong Meixiang Ning Hongbo Problems in the production and application of alumina, and proposed improvements and construction

Non-ferrous metal DI type mobile chamber belt vacuum filter in the production of aluminum oxide in the application of existing problems and their improvement measures exist in production applications there 6789; Jincai China Aluminum Shanxi Branch He Zhengmin Cao Junling Dong Meixiang Ning Hongbo alumina production Problems in the application, and put forward improved measures and suggestions. Through targeted improvement, good results have been achieved in practice.

1 Preface National “Science and Technology Key Projects A sandstone alumina production technology R&D project was launched at the production site of China Aluminum Shanxi Branch from the beginning of 2002. Among them, the sand-like alumina seed production and semi-industrial production test line is a research and development process. The most important part of the trial was the construction of the pilot line in January 2002, completed in August, started commissioning on September 5, and successfully entered the pilot phase by the end of September. So far, the trial has achieved major technological breakthroughs and significant The results of the test line in the design, testing process selected the current domestic and international more advanced solid-liquid separation equipment - a DI-type mobile chamber with a vacuum filter, for the sand crystal alumina seed filtration and product filtration, washing. Practice has proved that the machine has continuous automatic feeding, filtering, washing, discharging, draining, cleaning filter cloth, correcting and other effects, high production efficiency, filter cake with less liquid, good washing effect, simple operation, easy maintenance, etc. Features.

In the experiment, one of the main equipments used in the filtration of aluminum hydroxide products is DI2.8/400N. Two main equipments for crystal seed filtration are model DI18/2000N. Because the machine is used for sand Alumina production test is still the first time in China. It is due to unskilled operation, different process conditions, and complex phases. It causes failures at the initial stage of operation and affects the normal operation of the test to varying degrees. Under the targeted transformation, the field test requirements were met, and the operating conditions of the equipment were greatly improved, laying a solid foundation for early results testing.

2 filter working principle and flow chart When the filtration stroke begins, the slurry is distributed on the filter belt, the vacuum chamber and the filter belt move forward synchronously, the slurry on the vacuum chamber is filtered under the vacuum suction, the filtrate Through the filter chamber, pipelines, switching valve into the positive drain device and then discharged to the filtrate pool, the filter cake washed by washing and drying by the unloading device from the filter strip off, the filter cloth after washing and regeneration. When the vacuum stroke ends, the vacuum chamber touches the bidirectional switch, the vacuum is switched, the filter cloth is still moving forward at the original speed, the vacuum chamber is quickly pulled back by the reciprocating cylinder, touches the bidirectional switch, and the second filter stroke starts . The working principle and flow chart of the filter are as follows: 3 Existing problems and their causes 3.1 The main reason for the poor suction filtration problem is that the quality and performance of the L-filter cloth cannot fully meet the requirements of the filter medium. 2) vacuum switching valve is not normal; /) serious vacuum leakage, filter plate leakage at the junction, the rubber suction pipe is easy to rupture, sucker flange connection and leakage at the corner; 4) filter belt washing is not clean.

3.2 The main reason for the problem of deviation and wrinkling of filter belt is that L-) pneumatic guide film diaphragm is affected by environmental materials and steam, and it is easily damaged; 2) Rubber correcting roller is not wearable, after long-term operation, the cylinder becomes thinner. Or the surface is smooth, so that the friction force becomes smaller;/) When the tape is replaced, the length of the cutting and sewing is not uniform, and the elasticity is improper after installation; 4) The guide angle of the pneumatic guide roller is not non-ferrous metal. When the technology advances, both sides of the filter belt are caused. The uneven force, compared with the finished filter, the corrective roller specification and correcting force of the seed filter are not enough; C) The filter cloth is not clean and the regeneration performance is poor, resulting in the filter tape sticking material, and the two sides of the correcting roller pressing force are not Average; 6) The filter belt travel is too long, beyond the correction range.

3.3 The main reason for the problem of leakage of vacuum chamber connection and pipette is: The sealing or conveying material can not meet the requirements of the site of strong alkali media material, poor corrosion resistance.

3.4 The main reason for the malfunction or out-of-synchronization of the vacuum switching valve is: z) The valve body does not move; z) The nylon bush in the valve is not wear-resistant, corrosion-resistant, easy to pull, causing excessive clearance. ) The rubber seal gasket inside the valve is easily damaged or deteriorated; 4) The semi-circular parts inside the valve are easily affected by vibrations.

3.5 Reciprocating cylinders work poorly, and the main causes of vibration problems are: C) improper lubrication or under-lubrication, causing piston rods to pull hair; z) damage or severe wear of the seals; ) Displacement and looseness of cylinder assembly position;) Cylinder advancement, shrinkage speed and filter belt running speed are not synchronized; C) Infrared sensors that control the filter tray advance and retreat fail due to environmental influences.

4Improvement Measures and Suggestions We have organized technical personnel to tackle problems that have arisen during the operation of the filter and cooperated with the manufacturer to make the following improvements in a targeted manner.

Z) For the problem of poor suction filtration effect: reselect the filter cloth that meets the material performance requirements; change the original general rubber pipette to alkali resistant rubber pipe; reinforce the filter plate joints, and add stainless steel partitions in the middle. Two seal gaskets on both sides, and then tightened with bolts; Change the leakage of the switching valve to replace the rubber gasket and semi-circle parts in time, and add oil lubrication to the nylon sleeve inside the valve; take the filter tape adhesive Raise the water temperature and pressure of the cloth, replace the filter cloth, adjust the gap between the scraper and the filter cloth and the pressing force, and manually clear the solution.

z) For the problem of filter belt deviation: mainly adopt the method of adding a protective cover to the pneumatic film cylinder to prevent the alkali solution from splashing on the cylinder and causing cylinder failure; adjust the installation angle of the pneumatic guide roller, and replace the film film in time. In the original automatic correction device based on the addition of manual manual corrective device; replace the filter belt, pay attention to the length of the filter belt sewing interface, elastic; to strengthen the filter belt washing effect and reproducibility to prevent sticky material; adjust the length of the filter belt, Make it suitable.

z) For the poor operation of the reciprocating cylinder, the problem of jitter: mainly to increase the number of lubrication, timely cleaning the piston rod and replace the seal ring; re-adjust the position of the cylinder; adjust the filter plate advance and retreat speed to make it consistent with the filter belt running speed; Infrared sensor translocation and take protective measures.

z) In addition to setting the filter motor drive speed signal, filter belt slip signal, compressed air q road) low pressure signal in the main control room, filter left and right deviation signal, motor frequency conversion status, frequency conversion settings, it is recommended that the main control Add vacuum switch valve pressure alarm, four-way pressure overload alarm, filter disc running speed, filter belt running speed, drive motor overload alarm signal. Additional alarm signals are added to the electrical and pneumatic control cabinets at the operation site so that post operators can quickly handle the alarms when they hear them.

z) Through the application of practice, although the currently used pneumatic deflection correcting device has a certain role in preventing filter belt deviation and wrinkle, it is more suitable for small size filter), but the filter size is also large in accumulation) With long strokes, large material-to-liquid ratio, large specific gravity, and easy-to-adhere materials on the filter belt, the effectiveness of correction will decrease significantly. Therefore, it is recommended to add control deviation correction cylinders at the machine head and tail end under large-scale process conditions, or to flatten non-ferrous metals at the middle of the filter belt operation. Observation of Tural Aluminum Industry Su Hongying has compiled a relatively late start to the Turkish aluminum industry with only 30 In the history of the year, there is currently only one electrolytic aluminum plant located in Seyidiyeshir, Konya, with an annual production capacity of 60,000. It had planned to increase production capacity to 120,000 t/a, but due to the delay in the privatization process. Shelved. At present, Turkey's per capita consumption of aluminum is 3kg/a. Since 1975, the growth rate of Turkish aluminum consumption has been between 80% and 150%. Turkey's aluminum consumption level is currently 220,000 t/a, and it needs to be imported every year. The original aluminum and processed materials are 130,000, which is a net importer of aluminum and processed materials. It cannot be compared with European average consumption level of 18kg/a and Japanese per capita consumption level of 31kg/a. However, due to its population of 75 million, of which 30 are. The majority of the population under the age of majority is a promising aluminum market with great potential for consumption.

The Seyidiyesche electrolytic aluminum plant is a state-owned enterprise, aluminum-sailed earth mines are nearby, and most of the other aluminum companies in Turkey are private companies. The total production capacity is: 75,000 t/a of extruded products; Products 90,000 t/an cables and conductors 55,000 t/a. Turkey is both an aluminum consumer and a primary aluminum producer. The construction industry is currently developing, with 24% of the automotive industry in market share and 10% in the electronics industry. , packaging industry 15%. However, due to * 50 page) roller correction device to prevent serious run-off and wrinkle filter belt.

6) Through practice, we have found out that the DI-type mobile chamber belt vacuum filter is an ideal part of the process control conditions for sand alumina production test applications: the filtered compressed air pressure! 0.4MPa, filter washing water temperature! 90! , washing cloth water temperature 60! "70!, water pressure! 0.3MPa; corrected cylinder pressure of finished product filter 0.1MPa~0.15MPa, tension cylinder pressure 0.1MPa~0.15MPa, reciprocating cylinder pressure 0.35MPa" 0.55MPa, vacuum switching valve pressure 0.2MPa" 0.25 MPa, frequency conversion motor power 10Hz~12Hz; seed filter correcting Turk's economic instability, resulting in insufficient start-up rate of extrusion production, only 60% of extrusion capacity in production, production of dairy products since the economic crisis in 2001 Due to lack of capacity, the capacity utilization rate has dropped by 25%. Turkey's industrial production is still dependent on imports, but macroscopically speaking, many local Turkish companies are striving to open up export markets. At present, there are 20 of Turkey’s industrial output value of 1.25 billion US dollars. % is earned through exports.

Turkey has many small aluminum extrusion plants and competition among them is fierce. Therefore, the price has become the second largest competitive factor after quality. Despite the huge domestic market demand, 30% of the extruded products are exported to France. , Germany and Israel. In particular, investments have been made in the production of aluminum doors and windows, and 8109 can now be produced. Assan Demi, a Turkish dairy company, has already achieved production capacity of 110,000 t/a. Due to fierce competition, the plant is raising funds to invest in the aluminum industry to expand its domestic market share.

Due to Tur’s current political and economic environment, foreign investment is currently very low, mainly in the packaging industry. After Turkey is joined by Turkey, the Turkish aluminum industry will have great development.

Offset cylinder pressure 0.15MPa "0.2MPa, tension cylinder pressure 5 Conclusion Through the above-mentioned targeted improvement, the failure rate of the filter is greatly reduced, the operating cycle is extended, the production efficiency and the operating rate are significantly improved, and the maintenance cost is also saved. It ensures the long-term and stable operation of the entire process system, thus laying the foundation for the normal and continuous testing.

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