On-line measurement of particle size by microwave technology

The establishment of technology for closely controlling the distribution of sinter and coke in the blast furnace has been gaining importance in order to assure the stability and flexibility of furnace operations. The particle size measurement of the burden materials as charged is considered essential to this end. It was planned to develop a new particle size measuring technology, and microwave technology was employed as basic tool for the project. Theoretical study and basic experiment made it clear that microwave scattering intensity in the frequency range of 3 to 10 GHz has linear functional relationship with the particle size of the burden materials in the size range of 5 to 100 mm. Full-scale model test achieved an accuracy of ± 1.5 mm over the sinter size range of 5 to 25 mm. The new technology took the form of a microwave particle size meter, which was installed in the No. 4 blast furnace of Kimitsu Works in 1988 and has been smoothly operating ever since.