What is the logic behind pushback generation?
The logic is as follows: Obtain a progression of pits that when mined bench by bench will maximize the NPV subject to the following practical requirements: • Each pit, with the possible exception of the last one, is not smaller than a specified size (it may be larger). • Each pit contains spatially connected blocks; that is, it cannot consist of disjoint holes in the ground. • An access to each pit must be guaranteed. This is defined as follows. A given pit in a sequence of push-backs can be an extension of an earlier pit, or it can be located in a different sector of the mine sharing no common areas with the earlier pits. If the pit is an extension of an earlier one, then the boundaries of the two pits must coincide wherever they are identical with the final pit limits; anywhere else, the boundaries must be separated by a distance that is not less than the value of the Access Space Parameter. The Pushback Generator takes the blocks from the extraction sequence and builds spatially con
