Research On Open Pit Reserve Dynamic Evaluation For Porphyry Deposits And Application

Mineral resource/reserve classification is used for reserve estimation.Reserve estimation is a dynamic process throughout all stages of mineral exploration,ore extraction and mine closure.Therefore,finding out a new theory,methodology and technical tool related to mineral resource/reserve classification is quite important for the resource department of local government,exploration brigades and mining companies to have a better reserve estimation for the projects they own.A full theoretical and case study on mineral resource/reserve classification is based on surface mining with porphyry deposits.In this study,a new classification system,called Open Pit Reserve Dynamic Evaluation Program or OPRDEP,has been set up by following geological assurance and economic viability,which is described below.(1)The OPRDEP covers resource estimation,reserve report and updating reserve information.It is suitable for the porphyry deposits with no clear ore/waste contact.The OPRDEP has a clear structure and high practicality and is suited for deposits with indistinct boundaries.(2)A thorough study of the critical techniques of resource estimation has been carried out,which leads to the introduction of a series of algorithms to upgrade the current mining software,such as Radial Basis Function(RBF)and Marching Cubes(MC)algorithm for wireframe modelling,Locally Varying Anisotropy(LVA)algorithm for data searching,and Minimum Search Pattern(MSP)for the generation of Initial Directed Graph.As a result,a vast improvement on the efficiency and accuracy of resource estimation has been achieved in domestic software,which brings it a step closer in completing in the international market.(3)The geological assurance code in the refined resource classification scheme was defined as two levels,namely Exploration Zone and Local Domain.Geostatistics is distinct in terms of evaluation unit,interpolation method,influence factors and quantifiable accuracy.In view of the different features of the Exploration Zone and Local Domain,this paper was put forward based on block model and geostatistics,which laid a foundation for improving resource classification scheme.(4)A refined resource classification scheme has been built which incorporates the existing three-axis EFG(Economic viability,Feasibility assessment,Geological assurance)classification system with an innovative split in the last axis.It involves world’s best practice,and therefore will resonate within the mining.industry in China for its significance in resource management and corporate governance.(5)The determination of final open pit was proved to be a general reflection of the economics of the deposits whereas the value of selective mining unit to be a measurement of the profitability for a portion of the orebody.On a dynamic level,the adjustment in the cut-off grade should be a direct response to the price,cost and grade distribution,and the skeleton of the economics,strategy and management of open pit mining.(6)Experiment shows the OPRDEP discussed details in this paper is highly effective for large-scale porphyry deposits.It improves the timeliness as well as the accuracy of the resources and reserves estimate.Overall,it generates significant value for mines and therefore should be studied and implemented at a broad level.