John Clout

The CSIRO Hopkinson Bar Facility for large diameter particle breakage

The new CSIRO Hopkinson Bar Facility has been commissioned at the Queensland Centre for Advanced Technologies in Brisbane, Australia. Similar devices, such as the Ultra Fast Load Cell (UFLC) at the Utah Comminution Centre have proven to be extremely useful in providing fundamental breakage data of particulate material. In addition to its 19 mm and 60 mm diameter Hopkinson bars, the new CSIRO facility includes a large 100 mm Hopkinson Bar. This large diameter carbon steel load cell is instrumented with highly sensitive semi-conductor strain gauges that give it a force resolution of less than 100 Newtons, permitting precise measurement of the energy to fracture large mineral particles. The devices ability to measure breakage properties, such as first fracture force and energy, of large particles up 100 mm is unique. Breakage data for iron ores over a wide size range is presented. The well known comminution result of increasing particle strength and fracture energy with decreasing particle size was confirmed for the iron ores tested. The influence of iron ore mineralogy and texture was also noted.

Mathematical Modeling and Optimization of Iron Ore Sinter Properties

The quality of iron ore sinter is a critical factor determining the productivity of blast furnaces for iron-making. CSIRO has therefore been developing capabilities for predicting sinter characteristics, which enables sinter quality to be improved/optimized and preliminary assessments to be made of the suitability of specific ores or ore blends for sinter production. An extensive database of pilot-scale sintering experimental results has been used to create mathematical models for predicting different sinter properties. In addition to size distribution and other physical and chemical characteristics usually used for sinter quality prediction, the mineralogical and textural characteristics of iron ores intended for sintering have also been taken into account. This approach has been quite successful, the variation of sinter reduction degradation index (RDI) that is accounted for by explanatory variables (R-Sq) being 87%, for example. Optimization criteria have been developed that take into account several sinter characteristics simultaneously, and optimization of different iron ore blends to produce target sinter characteristics has been carried out. Modeling results and their preliminary validation are discussed.

Effect of fluxes on high iron and low silica sintering

Burnt lime and serpentine were incorporated into the sinter mix to improve high iron and low silica sintering. Optimization of how to use burnt lime including dosage of burnt lime, moisture of sinter mix, hydrating and granulation time was performed. Evaluations of sinter characteristics including sinter mineralogy, reducibility, low temperature reduction degradation, softening and melting down properties were carried out. Compared with the results of traditional process in base case, the tumbling index (TI) is increased by 1.53%–2.33% through proportioning high ratio of burnt lime or adding serpentine in the sinter mix. It is shown that effective granulation, better permeability and improved high temperature reactivity in the sinter bed are achieved, resulting in an increase in 3.13%–5.10% calcium ferrite occurring in acicular and columnar shape and decrease in glass phase, and with the reducibility index(RI) being increased by 1.65%–3.25%.