example of the blending network is depicted in Figure 1. Figure 1 – Four-layer blending network. Mines have a maximum production per day as well as an operating cost per ton. Mines may contain multiple geometallurgical domains, which each have their own distinct chemical and mineralogical characteristics, the topology of which are not modeled (other than an order of precedence). Since we focus on sedimentary phosphate deposits in this work, geometallurgical domains are represented as mine layers. These are represented as probability distributions with means and variances. For each simulation, a new feedstock composition realization is generated to represent the uncertainty in the feedstock. Feedstock composition values vary with respect to tonnage, and the measured value reflects the composition averaged over the tonnage extracted. An example of a mine with four layers with distinct characteristics is shown in Figure 2. It depicts a representative realization of P2O5 variability in each layer, along with light shaded bands representing the range of fluctuation over 100 simulations. By default, one layer is excavated from a mine each day until it is exhausted, at which point the next layer is excavated. A user-defined layer excavation schedule which specifies which layer should be excavated from each mine on each day can be provided for the simulation. Overburden and interburden layers are ignored for simplicity. Piles store inventory up to a capacity limit, which is typically high enough to be irrelevant. Piles optionally can start with an initial inventory. Fixed mine and pile parameters are presented in Table 1.
RkJQdWJsaXNoZXIy MTM0Mzk2