Abstract:

Underground metal mineral have the characteristics that resources condition and underground conditions are complex，with diverse mining methods.Apart from this，mine production is always in an uncertain and constantly changing dynamic process.How to obtain a scientific and effective production plan quickly has always been an urgent problem for mining enterprises.In order to solve this problem，a variety of production planning methods are used in the production process of mines，such as multi-objective programming algorithm，mixed integer programming，genetic algorithm，quantum particle swarm optimization，critical path method，and so on.The risk of uncertain in production process of mines often result in fail to complete the project on time，which will have a significant influence on the reputation and income of the mining enterprises. For the purpose of solving the problem of uncontrollable shortest construction period and high operating cost existing in traditional underground mining plan preparation，an automatic search method for the critical path of mining plan under resource constraint was proposed.Firstly，a network diagram was generated automatically according to logical relationships （subsequent operations，start time，end time and process ID） between operations，and resource constraints for the chart need to be add.Then，the current process of each stope was determined according to the information in the process sequence and the plan connection table，and assigned priority to different processes according to different resource allocation priority rules.The priority of first process in every stope was assigned according to the earliest start time of the operation and resource demand intensity，and the priority of the remaining processes was determined according to the completion time of the previous process in process sequence and resource intensity.At last，the network diagram under resource constraint needs to be updated，taking current node as an initial node，an improved depth-first search algorithm was used to traverse the directed graph，and find all mining paths in current process recursively. The path that taken the longest time was critical path，which represented the current shortest completion time of the mining plan under resource constraint.The idea of critical chain was applied to the Sanguikou mine of Zijin Mining，and the result shows that the method uses for optimizing the mining plan makes full use of the advantage of critical chain management.The method not only solves the problem of resource constraint and the shortest construction period，but also shorten the time for planning and the time for mining plan.What is more，it reduces the operation cost.During the construction period，the adjustment and optimization of the mine plan were completed，and the sustainable and efficient production of the mine was realized finally.

Key words: underground mine, preparation of mining plan, critical chain, optimal allocation of resources, depth-first search algorithm, network diagram