The production of a mineral commodity is a two-stage process: mining to extract the commodity from the ground, and processing to convert the commodity into a marketable end product.

Traditionally, these two stages have been viewed as self-contained entities. In fact, great strides have been made over the years in the stand-alone optimization of each entity. Unfortunately, mining and processing are intimately linked, particularly in the area of particle size reduction. Thus, optimizing each stage separately without considering the total system often misses potential economic benefits and energy savings. This is particularly true in the aggregates industry where the sole objective of each operation is to produce crushed stone of various sizes.

Since 1998, JKMRC researchers have been conducting mine-to-mill optimization research at operations throughout the world. Mine-to-Mill™, as the name implies, is the holistic approach to mining and mineral processing. Developed at the JKMRC, it provides a complete fragmentation and size reduction solution to maximize benefit. The entire operation is taken into account, from the blasting process to the comminution circuit performance and the interactions between them, in order to optimize the entire size reduction process. Mine-to-Mill™ optimization has been successfully applied in gold, copper, and lead/zinc operations throughout the world producing increases in throughput from 5 – 18% and cost reductions in the neighborhood of 10%.

The aggregates industry appears to be a perfect candidate for Mine-to-Mill™ optimization since its main focus is particle size reduction through blasting and crushing. The aggregates industry represents the largest segment of the U.S. mining industry, accounting for more than two-thirds of the non-fuel minerals produced, and over half of all mined commodities when coal is included. In fact, 1.6 billion tons of crushed stone are produced annually in the U.S., at a value of nearly $9 billion. Since a typical crushed stone quarry consumes approximately 1.65 kWh/ton, over 2.6 billion kWh of electrical energy are consumed per year by crushed stone production. Clearly, if there is a segment of the mining industry where energy saving research can have an impact, it is the aggregates industry.

Unfortunately, this major segment of the U.S. mining industry has been virtually ignored by researchers and funding agencies. Furthermore, Mine-to-Mill™ optimization has yet to be applied to the aggregates industry at any location, worldwide. The aggregates industry presents a unique challenge to Mine-to-Mill™ optimization in that, unlike the metal mining industry, its goal is particle size control as opposed to particle size reduction. Whereas increased particle size reduction during blasting may be a benefit in the metal mining industry, this may actually be a problem in the aggregates industry if the increased blasting energy results in the creation of fine particles that cannot be marketed. Thus, additional research is needed in order to translate the Mine-to-Mill™ approach, currently being tested in the metal mining industry, into effectiveness in the aggregates industry.

The purpose of this project is to adapt the Australian Mine-to-Mill™ optimization technology into an effective tool for the reduction of energy consumption in the U.S. aggregates industry. The first year of the project will involve sampling, modelling and simulation of the blasting operation and all crushers and screens at two U.S. quarries. Two computer programs will be used in this simulation effort, JKSimBlast and JKSimMet. Both programs were developed by researchers at the JKMRC. The models used in these programs are true physical models of the processes involved and are not based on manufacturer production estimates. Thus, the simulators developed for each quarry site will be accurate representations of the operations at each site. During the second year of the project, the simulators developed during the first year will be used in conjunction with cost and energy data to optimize the operations at both sites. These optimization studies will be carried out for the purpose of energy savings and cost reduction. Those alternatives deemed most promising will be implemented on-site and a detailed sampling campaign will be conducted to evaluate the alternatives tested and to quantify any energy and cost savings.

Contact Information
Isles Road, Indooroopilly, Qld Australia 4068
Phone:+61 7 3365 5888
Fax:    +61 7 3365 5999
Email: jkmrc@uq.edu.au