Ferrosilicon alloy granules prepared through centrifugal granulation process
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ORIGINAL PAPER
Ferrosilicon alloy granules prepared through centrifugal granulation process Wen-chao He1,2 • Xue-wei Lv1,2,3
•
Zhi-ming Yan1,2 • Gang-qiang Fan1,2
Received: 4 September 2019 / Revised: 23 November 2019 / Accepted: 24 November 2019 Ó China Iron and Steel Research Institute Group 2020
Abstract A novel granulation process that involved the use of a rotary multi-nozzles cup atomizer and water cooling was proposed for ferroalloy manufacturing. The effects of rotating speed and nozzle diameter on the properties of FeSi75 alloy (containing 75 wt.% Si) granules were investigated. Results indicated that median granule diameter decreased as rotating speed increased, and initially increased and then decreased as nozzle diameter increased. The optimal conditions for the granulation of FeSi75 alloy were a rotating speed of 150 r/min and nozzle diameter of 10 or 12 mm. The phase composition, micromorphology, and elemental distribution of the FeSi75 alloy granules were also studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectrometry. In order to provide guidance for the layout and water depth of the tank, the solidification behavior of ferrosilicon alloy droplet was numerically studied. A simplified model was established to elucidate the traveling trajectory and heat transfer of alloy droplet in air and cooling water during the atomization process. The solidification time of droplet with different thicknesses of solidification layer increased with the increase in alloy droplet diameter. Keywords FeSi75 alloy Rotary multi-nozzles cup atomizer Size distribution Microstructural analysis Solidification behavior
1 Introduction Ferroalloys are important metallurgical furnace charges that can considerably improve the physicochemical and mechanical properties of steels [1]. Ferroalloy particles are mainly manufactured through the mold casting and mechanical crushing process, which comprises mold casting, slag removal, mechanical crushing, and secondary processing. This industrial process, however, is associated with the problems of low productivity, product composition segregation, and environmental pollution. Up to & Xue-wei Lv [email protected] 1
Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials, Chongqing University, Chongqing 400044, China
2
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
3
State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing 400044, China
20 wt.% of the Si content of ferrosilicon alloy ingots undergoes segregation [2]. Product segregation, in turn, drastically affects the quality of alloy granules. The segregation of the ferrosilicon alloy is attributed to the difference between the phases densities, and the segregation degree depends mainly on solidification time. The solidification time of ferrosilicon alloy granules produced by direct granulation processes is clearly less than that by mold castin
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