| Particulate matter emissions are one of the main causes of air pollution in our country.Among them,the iron industry exhaust gas is a key source of particulate matter emissions.The particulate matter emitted by the iron industry has the characteristics of wide particle size distribution and the existence of fine particulate matter.The general organic filter media such as P84,PPS,Nomex fiber filter media and PTFE membrane filter media are mostly resistant to temperatures below 240°C,which makes it difficult to operate stably in such high-temperature environments.However,the commonly used high-temperature resistant glass fiber filter media did not have excellent trapping ability for particle of small size,and has the disadvantage that its own corrosion resistance will decrease with the rise of the use temperature;at the same time,the PTFE coated filter material with high filtration efficiency did not have good high-temperature resistance,and the PTFE membrane will creep and fail in a high-temperature environment exceeding 250℃.Compared with the above-mentioned filter materials,the high temperature resistance of basalt fiber filter media is better than that of primary high temperature filter media.At the same time,it has excellent acid and alkali resistance,oxidation resistance,and hydrolysis resistance.It has development prospects in the field of high-temperature filtration;however,the conventional basalt filter material has relatively coarse fibers,and has the disadvantages of uneven pore size distribution and large average pore size,which leads to poor filtration performance for ferromagnetic metal particles with small particle diameters.Therefore,In this paper,basalt filter media fibers are prepared by in-situ polymerization to load nano-cobalt ferrite basalt fibers,and used this as a raw material to prepare magnetic basalt filters,to study its ability to trap fine particles in a high-temperature dust removal environment.This paper mainly analyzes the basic performance gap between the nano-cobalt ferrite basalt fiber and the original basalt fiber,and the influence of different preparation methods on the basalt fiber-loaded nano-cobalt ferrite.The magnetic basalt filter material was prepared by carrying nano-cobalt ferrite basalt fiber through acupuncture process,and its performance was compared with the original basalt filter material.Then,the filtration performance of the magnetic basalt filter material,such as classification filtration efficiency and filtration resistance was tested.The specific research work is as follows:Firstly,two sets of nano-cobalt ferrite basalt fibers were prepared by in-situ polymerization and dipping methods respectively by using basalt fibers as raw materials,and the performance gap between the two sets of fibers and the original basalt fibers was studied.The effects of two preparation methods on the deposition effect,distribution,surface functional groups and magnetic properties of cobalt ferrite particles on basalt fibers were compared.By Scanning Electron Microscopy(SEM),X-ray Diffraction(XRD),Infrared Spectroscopy(FTIR),and Vibrating Sample Magnetomter(VSM).Compared with the original basalt fiber,the in-situ polymerization method caused the strength of the basalt fiber after loading nano cobalt ferrite to decrease by 4.6%,while the dipping methods would not;three groups of fibers were all acid and alkali-resistant fibers.After heating at 200°C for 2 hours,the fiber strength decreased significantly.The loaded nano-cobalt ferrite basalt fiber prepared by in-situ polymerization had high crystallinity and better crystallization effect withthe coercivity was±2138Oe,and the residual magnetization was8.71emu/g.However,the coercivity of the loaded nano-cobalt ferrite basalt fiber prepared by the dipping method is±2078 Oe,and the residual magnetization is 2.48 emu/g.Secondly,the magnetic basalt filter material was prepared by acupuncture process,and the performance difference between the magnetic basalt filter material and the original basalt filter material in terms of pore size distribution,mechanical strength,temperature resistance and acid and alkali resistance was studied,and the stability of the magnetic basalt filter material loaded with nano-cobalt ferrite was also studied,.The results show that:compared with the primary basalt filter material,the magnetic basalt filter material has a larger weight,slightly lower air permeability and strength in the latitude and longitude directions,a more concentrated pore size distribution,and a smaller average pore size.The primary basalt filter material and the magnetic basalt filter material have a breaking strength retention rate of more than 95%in the longitudinal and latitude directions below 250℃,and both show similar acid and alkali resistance,with poor alkali resistance and excellent acid resistance.The removal rate of the magnetic cobalt ferrite particles of the magnetic basalt filter material has no obvious relationship with the filtration wind speed,and the removal process of the magnetic cobalt ferrite particles mostly occurs in the first 10minutes of filtration.Finally,the filtration characteristics of the magnetic basalt filter were studied.When the filtration wind speed is 5m/min and the dust concentration is 50mg/m~3,the filtration efficiency of the primary basalt filter media and magnetic basalt filter media is not high for dioctylsebaeate (DEHS)and Fe-based magnetic particles with a particle size range of 0～0.5μm;For DEHS particles with a particle size range of 0.5～4.0μm,compared with the primary basalt filter,the magnetic basalt filter exhibits a filtration efficiency of about 20%higher than that of the magnetic basalt filter with Fe-based magnetic particles in the same particle size range.It exhibits a filtration efficiency of 20%～40%higher than that of the primary basalt filter;for particle size range bigger than 4μm,the magnetic basalt filter material can improve the filtering effect with the help of magnetism.After processing the magnetic basalt filter material at different high temperatures for24 hours,the filtration performance of the magnetic basalt filter material did not change greatly with the change of temperature.The filtration resistance of the original basalt filter was lower than that of the magnetic basalt filter during the initial filtration,but as the dust load of the filter was increasing,the influence of the cobalt ferrite of the magnetic basalt filter on the filtration resistance of the filter became smaller. |
