BHP Billiton iron ore produces approximately 110 million tones per year of Brockman, Marra Mamba and Pisolite iron ore in two product types; lump (6 to 31mm) and fines (<6mm), from four separate mining areas in the Pilbara. The worldwide increase in demand for iron ore, and its expected continuance, has led the company to identify opportunities to increase tonnages.
BHP Billiton Iron Ore has reviewed the operating principles of its entire value chain as well as conducting investigations into the potential upgrading of existing mines and infrastructure along with the development of new mines. Assessment of expansion options requires informed choices involving alternative modes of operation and development. These alternatives can differ greatly in expected capital and operating costs. Reviewing the many options that existed is very complex. Resource modeling, infrastructure and capacity modeling along with product grade quality modeling is needed to ensure delivery of the expanded tonnage of ore, safely, at minimum operating and capital cost and at an acceptable quality to the customer.
Simulation modeling was chosen as the appropriate tool for the reviews because of the complex relationships in each alternative. For BHP Billiton Iron Ore, the operating and infrastructure changes to achieve tonnage were studied in one simulation system while the effect on product grade quality was simulated in separate model. This paper describes the simulations carried out to assess product grade quality. These simulations were based on infrastructure and capacity options identified from the tonnage simulations. They were
set up so that the impact of changes to operating practices on product grade quality could also be assessed.
Two particular operating models are referenced in this paper; the Mt Newman Joint Venture, a series of four mines generating a lump and fines product and the Yandi operation with two operating areas where only fines product was studied.
At the mine, monthly mine plans take into account the cost efficient use of the resource. Ore blocks are blasted and assigned into floorstocks of consistent geology and composition using analysis from samples taken during the drilling of the blast holes. Each day, ore for mining is selected from blasted floorstocks taking into account the target grade requirements, the current deviation from
target, and cost efficient mine development. In the case of the Newman area mines, partly processed ore from four mines is railed 400
kilometers to the port where it is crushed, separated into lump and fines products and stacked onto stockpiles typically of 150 kilotonne capacity.
The methodology used for stacking ensures optimum blending within a stockpile. Lump product is re-screened before ship loading.
Ore from completed stockpiles is reclaimed and loaded onto ships through multiple ship loading berths and transported to customers. Everett (1996, 2001) discusses methods of iron ore quality control. Kamperman et al (2002) describe application of these methods to BHP Billiton’s Yandi operation.