The many different types, grade and physical properties of each ore makes each type unique. The different physical properties of the ores can significantly impact how the material behaves in the downstream processing steps. The Properties and End-Use Functionality of Iron Ore Program is concerned with quantifying the properties of iron ore as well as granulated material and sinter. The knowledge and deep understanding that is built up around the various ores and ore types is critical to inform the supply chain from mines to end user if the full potential of the ore is to be realised by the miner.
The blended sinter mix undergoes a process of granulation prior to charging onto the sinter machine. Through the careful addition of moisture, ultrafine particles (less than 0.25 mm), typically adhere to the fine particles larger than 0.5 mm in size, forming agglomerates. It is essential to understand, at a fundamental level, the relationship between ore properties and the potential for agglomeration. Granulation experiments are carried out in our laboratory in a small scale granulation drum. Fine iron ore can be mixed with water and a range of potential additives, and granules produced for further testing. A range of techniques has been developed to characterise the properties of the iron ore fines and the produced granules.
Work is progressing to model size segregation of agglomerates down a sinter bed using discrete element modelling (DEM), with experimental validation. In this work, the effects of a number of agglomerate properties and sinter plant operating conditions, such as size distribution and feed rate, on vertical size segregation in the sinter bed are studied.
Laboratory Granulation Drum
DEM Model of granule pile formation
The two objectives of this area of research are; to understand the key properties of sinter that control quality parameters such as strength and reducibility; and to understand how sinter quality can be maximized by modifying process conditions and / or iron ore blends, while maintaining productivity and minimising operating cost.
Sinter represents approximately 70% of blast furnace feed in Asia. The properties of the sinter, such as strength, reducibility and other high temperature properties go a long way to determining the overall productivity and efficiency of the iron making process. Our laboratory has a range of experimental equipment for measuring sinter quality and properties, such as reducibility. We have also developed a numerical model of the sintering process for BHP Billiton, which has been validated against a range of pilot scale sinter pot tests. This research will also involve collaborations with; CSIRO QCAT and Zhejiang University, to carry our pilot scale sintering experiments; CSIRO Clayton for in-situ XRD studies; and the Australian Synchrotron for characterization of sinter structure.
High temperature laboratory for studying sintering reactions
The objective of this research is to investigate the link between different ferrous material properties and the behaviour and performance of these in the blast furnace.
The iron making blast furnace converts ferrous materials in the form of sinter, lump and pellets into hot metal. Unlike iron ore sinter and pellets which are manufactured from iron ore fines and or concentrate, lump can be directly charged to the furnace without any pre-processing. As a result, lump has an inherently higher value compared with fines due to the avoidance of agglomeration costs. Australia is a significant producer of iron ore lump. While customers in traditional markets such as Japan, Korea and Taiwan value and utilize Australian lump ore at high levels, Chinese customers are less experienced with Australian lump ore and don’t assess it at its full value. Our laboratory has a range of experimental high temperature furnaces for determining the properties of ferrous material for the blast furnace, including a softening and melting (S/M) test to simulate behaviour of material in the cohesive zone. Techniques have been developed to quench samples from the S/M test and analyse the results using optical microscopy.
Our previous work, confirmed by discussions with iron makers and researchers in China, has highlighted the importance of interactions between mixtures of ferrous burden in the cohesive zone of the blast furnace. Work is in the planning stages to investigate this interaction on a more fundamental level, considering the interface between individual particles rather than the bed of material that is tested in the S/M rig. Synchrotron x-ray computer tomography is being investigated as a tool to characterise the three dimensional structure of quenched samples from the S/M test.
Optical microscopy and image analysis is used by Hub researchers to investigate the products of high temperature experiments