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Zeljka Pokrajcic Awarded Inaugural Vittorio de Nora Prize
By Lynne Robinson

News Article Image Posted on: 11/04/2009
Zeljka Pokrajcic sees her work as an adventure.

“I wasn’t really sure what metallurgy was when I was considering a degree in engineering,” said the senior process design engineer for WorleyParsons—Mineral and Metals Division in Melbourne, Australia. “A friend studying chemical engineering suggested metallurgical engineering, as it provided exciting work opportunities in a variety of industries and locations. The idea of mineral extraction involving large and imposing machinery that sometimes operated at extreme conditions, as well as the prospect of traveling to exotic locations sounded exciting.”

Now a doctoral candidate at the Julius Kruttschnitt Mineral Research Centre (JKMRC), University of Queensland in Brisbane, Australia, Pokrajcic’s most recent explorations, under the guidance of her Ph.D. supervisors, Rob Morrison and Bill Johnson, have lead her to develop a methodology that promises to significantly decrease the energy consumption of comminution circuits in mineral processing. Her work has earned her the distinction of being named the first recipient of the Vittorio de Nora Prize for Environmental Improvements in Metallurgical Industries, established by the TMS Foundation this year. She will receive the award and make a presentation on her winning technology at the TMS 2010 Annual Meeting in Seattle, February 14-18, 2010.

“TMS leadership was pleased to work with the de Nora family to create the Vittorio de Nora Prize which recognizes ‘outstanding materials science research and development contributions to the reduction of environmental impacts, and particularly greenhouse gas emissions, as applied in global metallurgical industries, especially focused on extractive processing,’ said TMS President Ray Peterson. “Not only does the de Nora Prize honor the career of an outstanding industrialist, it also shows our TMS commitment to building the path towards a sustainable future that contains a strong and vibrant metals and materials industry.

“I am delighted by the selection of Zeljka Pokrajcic for her work in reducing energy consumption in comminution and congratulate her,” Peterson continued. “As the first of many future creative individuals to reduce our industrial impact on the environment, she shows that every human being can have a positive influence on our world.”

Describing her reaction to the news as “both honored and excited,” Pokrajcic said, “The award will significantly lift the profile of environmental improvements and increased energy efficiency in the minerals extraction industry. I hope that my contribution through the research already undertaken and the work planned as a result of the prize will further contribute to environmental improvements in metallurgical industries.”

Comminution, commonly referred to as crushing and grinding, is usually the first process in a mineral processing circuit and is typically the largest consumer of electrical energy in a mineral processing plant. Taking on the challenge to reduce the environmental effects, while increasing the efficiency of comminution technologies appealed on both a personal and professional level to Pokrajcic.

“I feel strongly about the environment and the choices we can be making as individuals and professionals to ensure the sustainability of our planet,” she said. “Improvement to comminution circuit design is an area where the benefits and reduction in energy usage can be greatest.”

Pokrajcic’s approach to a more energy-efficient comminution circuit design involves reducing the mass of material in the comminution circuit by rejecting coarse-sized, commercially worthless material before milling, as well as using more efficient crushing and grinding equipment. Improved ore analysis techniques that enable the selection of a coarser particle product size are also key to her methodology, since this requires less energy than achieving finer product sizes. Partially funded by the Center for Sustainable Resource Processing (CSRP), Pokrajcic’s research utilized modeling and ore characterization technology that had been developed at JKMRC.

“It is difficult to accurately predict the combined benefit of the energy-efficient strategies proposed in the research,” said Pokrajcic. “However, the ideas intuitively make economic and ‘energy saving’ sense. Approaches such as the use of more efficient grinding equipment and limiting the amount of grinding consumables can provide energy savings as high as 30 percent. So if these ideas were widely adopted, either in combination or individually, the energy savings would be huge. They can also improve productivity and the bottom line.”

To gain valuable insight into the economic impact of her proposed strategies compared with conventional processing, Pokrajcic will use the de Nora Prize funding to undertake an EcoNomics™ Assessment of comminution circuits employing her methodology.

“The ideas need a larger profile and, to be more convincing in the industry, require a cost benefit analysis,” said Pokrajcic. “The EcoNomics™ Assessment methodology will provide a simple dollar-for-dollar comparison which will hopefully be the impetus for industry to consider, and eventually implement, some of the energy-efficient design strategies.”

Developed by WorleyParsons, EcoNomics™ Assessment is a project evaluation methodology used to compare the environmental, social, and financial sustainability of project options. It allows the financial value of all internal project costs, as well as environmental and social cost factors, to be included in project evaluation on a like-for-like dollar value basis.

The first stage of the EcoNomics™ Assessment process for Pokrajcic’s project will be measurement and data collection to establish technical, environmental, social, and financial performance. Following that, simulation and modeling will generate environmental, social, and financial data for the baseline comminution circuit and those featuring Pokrajcic’s energy-efficient strategies. In the final evaluation stage, the results will be compared on the basis of financial, environmental, and social impact, with rigorous sensitivity analysis to understand the effect of future uncertainties on option selection outcome.

Once the assessment is completed, Pokrajcic plans to “publish the work and make it available to as many people as possible” and is eager to pursue further pilot test work on her methodology, as her adventures in —and contributions to—metallurgical engineering continue.

To meet Zeljka Pokrajcic and many other innovative young professionals like her, register for the TMS 2010 Annual Meeting today! Register before January 15, 2010 for a significant discount. Also take a moment to review the technical program, virtual exhibit hall, and networking opportunities.

Lynne Robinson is the news and feature writer for Materials Technology@TMS.

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