Study On The Electromagnetic Performance Of Chromite Ore Fines Containing Carbon In Volumitric Reduction By Microwave Heating

Microwave energy is a new type of heating energy, which can quickly and selectively heat powdery materials, avoiding nonuniform heat and matter transfer of powdery materials by traditional heating methods. Chromite ore fines containing carbon (COFCC) can be directly volumitricly reduced by microwave heating. Accordingly, more and cheaper COFCC can be best used.Microwave heating is to volumetricly heat matallurgy materials by dielectric and magnetic loss in electromagnetic field. Complex permittivityεand complex permeabilityμare two important physical parameters describing electromagnetic performance of matallurgy materials, which express the interactional relation and mechanism between matallurgy materials and the electromagnetic field. During the volumetric reduction of COFCC by microwave heating, the electromagnetic performance's behavior change of COFCC has great influence on heating and reducing effect. Therefore, in the course of volumetric reduction of COFCC by microwave heating, it has a significant meaning to study the changing rule of the materials' electromagnetic performance and its influence on microwave heating effect.By use of HP8722ES vector network analyzer, the macroscopical electromagnetic parameters of COFCC and its composing raw materials in the frequency range of 2～18GHz are measured with the transmission/reflection method of wave-gide type. In this method, the wave-gide segment filled with the dielectric sample is a part of transmission system. Scattering parameters S₁₁, S₂₁ are measured and complex permittivityε, complex permeabilityμare calculated by middle variable parameters R, T.In the thesis it is studied the electromagnetic spectrum of the raw materials at the normal temperature in the frequency range of 2～18GHz, which contain chromite ore fines of India, chromite ore fines of South Africa, chromite ore fines of China, anthracite, soft coal, cal-lime and magi-lime. Their electromagnetic performance at the frequency of 2.450GHz is also studied. There are many factors influencing the electromagnetic performance of metallurgy minerals, such as frequency, composition, humidity, configuration and temperature. Composition and configuration are the most important factors of them. In the studying raw materials, the differences of composition and configuration resulted in the differences of the electromagnetic performance. According to the research result, the electromagnetic performance of Indian chromite ore fines, anthracite and cal-lime are better than that of South African chromite ore fines, Chinese chromite ore fines, soft coal and magi-lime.During the volumetric reduction of COFCC by microwave heating, COFCC is respectively heated to 1000℃, 1100℃,1200℃,1300℃. The electromagnetic spectrum and the electromagnetic behavior change at each temperature in frequency range of 2～18GHz is studied, their electromagnetic performance at the frequency of 2.450GHz is also studied. At each temperature, the dielectric property increases and the magnetic property decreases with the microwave frequency increasing. At a certain temperature, metal oxides formed in the volumetric reduction by microwave heating are the main factor inducing the change of electromagnetic performance of COFCC.