BUILDING DISPATCH STOCKPILES WITH REQUISITE CHEMICAL COMPONENT COMPOSITIONS

A network product planner (29) ascertains material levels required at dispatch stockpiles (15), for example by checking upcoming orders for material to be shipped by transport ships (19) to end customers. Tolerance bands for chemical components required at the dispatch stockpiles are then ascertained. The tolerance bands are defined by upper and lower expected value control limits for each chemical component. The network product planner (29) then passes the collected information to the optimization engine (29a), which finds the values of decision variables in the form of weights, that minimize variance of the chemical components in the dispatch stockpiles, whilst being constrained to comply with the specified tolerance bands of the chemical components. The network product planner (29) then passes the weight values to the rail dispatch controller (23) in messages (14). The rail dispatch controller (23) refers to the weight values when generating schedules for the trains (13) so that as they travel over rail network (11), trains (13) pick up material from mine stockpiles (9) and deposit material to dispatch stockpiles (15) in accordance with the weights to thereby create the dispatch stockpiles with chemical components complying with the tolerance bands and with variance of chemical components minimized.