Simulation Modeling of iron ore Product Quality for Process and Infrastructure Development
BHP Billiton has several iron ore mining operations in the inland Pilbara region of Australia. Iron ore is mined from open-cut pits, railed several hundred kilometres to two port processing facilities at Port Hedland. Here the ore is processed, blended and the lump product rescreened ready for shipment, mainly to Asia. Customers use the ore as principal feed in steel production.
A Typical Iron Ore Production System shows a simplified ore flow, although many operational variations exist. The recent sharp increase in iron ore demand has required a review of capacity. To deliver increased tonnage of ore safely, at minimum cost and acceptable quality, processes need to be upgraded, existing mines and infrastructure expanded, and new mines brought on line .
Expansion assessment requires informed choices involving alternative options of operation and infrastructure development that differ greatly in capital and operating costs. Multiple choices exist between alternative mining practices, ore processing, stockpiling, railing and ship loading operations. Any expansion option must be assessed to understand the effect on product quality.
Customers assess quality by both cargo grade, and inter-cargo grade variability. As well as iron, several impurities, principally phosphorus, silica, and alumina are important. To gauge the effect of expansion options on shipped product quality, simulation models have been built, enabling mining and handling configurations to be studied, for appropriate time periods.
Since ore production grade shows complex serial and cross correlations, totally synthetic data cannot be constructed. Production was therefore simulated from historic data of geologically similar ore, statistically adjusted to match potential operations. To help company personnel use the simulation models, they were written as Excel™ workbooks, driven by Visual Basic (VBA) macros, making full
use of the provided graphical capabilities.
The simulation models described in this paper have been extensively used to evaluate alternative expansion and development options. The company is using the results from the models to assess the effect on product quality for many processing and equipment options in determining it expansion direction.