Microstructure and Minerals Evolution of Iron Ore Sinter: Influence of SiO2 and Al2O3

Abstract

SiO2 and Al2O3 are two important minerals that can affect the mechanical and metallurgical properties of sinter. This investigation systematically studied the influences of these minerals and revealed their functional mechanisms on sinter quality. Results showed that with an increasing Al2O3 content in sinter, the sintering indexes presented an improvement before the content exceeded 1.80%, while the quality decreased obviously after the content exceeded 1.80%. With an increasing SiO2 content, the sinter quality presented a decreasing tendency, especially when the content exceeded 4.80%. Consequently, the optimal content of Al2O3 was ≤1.80% and that of SiO2 was ≤4.80%. The evolution of the microstructure and minerals in sinter showed that enhancing the Al2O3 content increased the proportion of SFCA generated, which improved the sinter’s mechanical strength, while excessive Al2O3 led to the formation of sheet-like SFCA with weak mechanical strength. Increasing the content of SiO2 strained the formation of SFCA and promoted the formation of calcium silicate, the mechanical strength of which is lower than that of SFCA. The research findings will be useful in guiding practical sintering processes.

Low Carbon Sinter Making: Use of Inert Gas to Improve Sinter RDI

“…This phase is formed towards the cooling cycle and tends to have glassy structure and is thus brittle compared to other phases Due to it's glassy texture and higher amount of alumina this phase is prone to crack generation. 19,32) The Al 2 O 3 in sinter was same through out the trial period, it might be possible that low P O 2 (due to nitrogen purging) favoured the formation of Calcium Ferrite type of phases in case of low RDI sinter. 3,[33][34][35]…”

A Short Review of the Effect of Iron Ore Selection on Mineral Phases of Iron Ore Sinter

“…), depending on the cooling rate. Most of the sinter quality (reducibility and degradation degree) was affected by the amount and shape of SFCA [35,[40][41][42][43][44][45][46][47]. As the cooling rate increased, the fractions of columnar and platy type (SFCA, SFCA-I) increased [39].…”

Improving High-Alumina Iron Ores Processing via the Investigation of the Influence of Alumina Concentration and Type on High-Temperature Characteristics

“…Meanwhile, iron ores A, C, and F possess a lower iron grade and higher loss on ignition (LOI), contributing to the formation of porous sinter and then weakening the sinter strength [36]. In addition, SiO 2 contents of iron ores are quite different and the influence on high-temperature characteristics of iron ores needs to be taken into account [30,39]. The low contents of MgO, P, and S of iron ores are beneficial to the sintering process [7].…”

“…However, the excessive increase of Al 2 O 3 content (>1.0%) is expected to result in a drastic deterioration in the properties of SFCA. Namely, the amount of sheet-like, columnar, and blocky SFCA with lower mechanical strength is increased significantly, while a substantial reduction in the amount of dendritic and eutectic SFCA with higher strength is detected [30][31][32][33]. Taking into account the impact of alumina concentration on high-temperature characteristics and the different alumina types in iron ores, considerable emphasis has therefore been placed on the influence of alumina types on high-temperature characteristics recently.…”