Microwave And The Mechanism Of Interaction Between Particulate Matter And Application Of Research

The state of the art of microwave applications, in particular, the mechanism of microwave interaction with matter, was reviewed in this Ph.D thesis. Based on Maxwell's equation and non-Debye relaxation theory, a new equation for the description of dielectric losses under microwave irradiation was developed for the first time. This equation can be applied to successively explain the microwave absorption properties of nickeliferous limonitic laterite ores, alumina, and rubber compounds, respectively. A microwave setup for measuring the moisture content of industrial materials was also invented. The moisture content of nonferrous and ferrous metals minerals concentrates can be measured accurately by using this microwave setup. In this thesis, the microwave techniques for detecting the microstructure of materials was developed and 10 patents was applied. The equation and the techniques developed in this thesis have been and will be found momentously significant to develop more microwave applications in materials sciences and metallurgical engineering. The main contents and conclusions obtained were as follows:â… ,For granular materials, microwave absorption properties of the materials is a non-Debye relaxation processes which is relevant to the microstructure of materials. The microwave absorption equation of the materials as follows: Based on the above equation, the microwave absorption properties of nickeliferous limonitic laterite ores, alumina, and rubber compound were successively explained. It was found that the relaxation time of nickeliferous limonitic laterite ores and alumina are inversely proportional temperature. Namely, the higher temperature is, the smaller relaxation time of the materials attained and the more microwave power absorbed by nickeliferous limonitic laterite ores and alumina is. It was also found that the relationship between relaxation time r of rubber compound and temperature T as follows:Ï„(T)=t₀exp(-B/(T₀-T)). Namely, the higher temperature is, the slower relaxation time change of the rubber compound attained. Moreover, the vulcanized rubber absorbed less microwave power.â…¡,In order to study mechanism of microwave interaction with materials, microwave field intensity is a key parameter. In the fields of microwave communication and microwave detection, the properties of materials under microwave irradiation are invariant. The microwave interaction with materials is linear. By contrast, in the fields of microwave heating and microwave chemistry, the properties of materials under microwave irradiation are variable and the microwave interaction with materials is non-linear. Development and advance concerning the fields of microwave interaction with materials were reviewed. Preliminary results are obtained by computation and analysis.â…¢,A microwave setup for detecting the microstructure and the microwave absorption properties of materials was developed. The microwave absorption properties of graphite powder-pitch mixture and other ore materials were successful studied by this microwave setup. Interestingly, good absorption properties of the graphite powder-pitch mixture could be obtained by adding graphite powder which is a conductor although the pitch do not absorb microwave. To study microwave applications in the fields of material and metallurgical engineering. the properties of materials under microwave irradiation is a key parameter relevant to the efficiency of microwave power which will decide whether microwave power can be applied successfully or not in the fields of materials and metallurgical engineering.â…£,In the metallurgical industry, the exact moisture content of the granular materials has to be determined in order to allow control of the water dosage, of the quality of the product,and of the reduction of applied energy. Moisture determination by microwave is applied in many branches of industry. However, few applications have been reported in the metallurgical industry. It has been shown that the penetration depth of microwaves is much greater than that of infrared radiation, and microwave methods can measure the volume moisture content of the materials. In addition, microwave methods are much safer and faster than ionizing radiation methods. Hence a microwave setup for measuring the moisture content of industrial materials was developed in this Ph.D thesis. And the moisture contents of nonferrous and ferrous metals minerals concentrates were measured by this microwave setup. It was shown that this microwave setup is a practical and accurate technique to measure the moisture content of mineral concentrate with the standard deviation of less than 0.5%. It was also shown that the sizes and the specific gravity of granular materials have influence on the precision of moisture measurement by microwave. Generally speaking, the larger the size of granular matter is. the lower precision of moisture measurement attained, and the lower specific gravity of granular materials is, the higher precision of moisture measurement attained. The environmental temperature has also influence on determination of the water content of granular matter by microwave, thus the value of the moisture content of the materials was compensated for.â…¤,In order to explore other applications of the method for detecting the microstructure of materials by microwave, the microwave detecting techniques developed here were also used in other fields. It is clearly shown that the microwave sensor technique can be used to detect plant water status accurately, to monitor the chemical reaction kinetics, to detect a shortage in tobacco box or bar, to measure flux of granular materials and even to acquire the information of various hydration states of salt hydrates. For example, the microwave sensor could be used in thermal analysis accurately and efficiently, which is a key technique in chemistry, metallurgy, mineralogy and geology. Comparing with the method of thermal analysis using TG, DTG, DTA, and DSC, the microwave sensor has the advantages of high accuracy, fast measurement and more convenience. While comparing with the IR spectroscopy, Raman spectroscopy and NMR spectroscopy et al., the microwave sensor has the advantages of low price, low power and more convenience also.In a word, a new equation for the description of dielectric losses under microwave irradiation was developed. This equation can be applied to successively explain the microwave absorption properties of nickeliferous limonitic laterite ores, alumina and rubber compounds at elevated temperature, respectively. The equation implies that the high temperature application of microwave in the fields of materials and metallurgical engineering is preferable. In addition, the microwave techniques for detecting the microstructure of materials were presented. The moisture content of nonferrous and ferrous metals minerals concentrates were measured by the microwave technique. It is a breakthrough in studying mechanism for microwave interaction with materials and it is of momentous significance in studying and developing microwave applications in the fields of materials and metallurgical engineering.