Sintering characteristics of titanium sands after grinding and its influence mechanism on the quality of sinter
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摘要: 通過細磨海砂礦研究其粒級分布、微觀結構和燒結高溫特性的變化,結合燒結杯試驗、掃描電鏡能譜分析等研究方法考察海砂礦粒級分布對燒結礦質量的作用機理.經細磨后海砂礦顆粒不規則程度增大,制粒性能得到改善.隨著海砂礦粒度變細,其燒結高溫特性呈現出與普通鐵礦粉相反規律,其中海砂礦3(細磨25 min的海砂礦)與海砂礦1(未經細磨的海砂礦)相比,同化溫度升高21℃,1280℃時液相流動性指數減小0.35,細磨后海砂礦與Ca O反應生成鈣鈦礦增多,阻礙同化反應進行,生成的液相黏度增大.配加8%海砂礦3的燒結礦與配加相同比例海砂礦1相比,還原性提高3.8%,細磨后海砂礦在混合料中分布更加均勻,造成燒結礦中含鈦物相質點增多,還原中產生眾多微細裂紋,利于還原氣體擴散.Abstract: The size distribution,microstructure and high temperature properties of titanium sands after grinding were studied in the paper. The influence and mechanism of titanium sands on the sinter quality were identified by sinter pot test and scanning electron microscopy and energy dispersive spectrometry(SEM-EDS) test. It is found that the micromorphology of titanium sands becomes more irregular after grinding,and the granulation gets strengthened. Meanwhile,the high temperature characteristics of sintering are different with the common iron ore fines: when titanium sands become finer,the assimilation temperature improves by 21 ℃,and the liquid phase fluidity index decreases by 0.35 at 1280 ℃. The reason for these differences is that titanium sands after grinding react with Ca O to produce more perovskite,which can hinder the assimilation reaction and get the liquid phase stickier. In comparison with unground titanium sands,the reduction index(RI) of sinters produced with 8% of ground titanium sands in blends improves by 3.8%. The reasons are that titanium sands are distributed more uniformly in blends after grinding,resulting in the increase of phase particles containing titanium in sintered ores,and many microcracks emerge in the reduction reaction,which is in favor of reducing gas diffusion.
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Key words:
- titanium sands /
- sintering /
- particle size distribution /
- microstructure /
- assimilation /
- fluidity
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