Study On Digital Assessment Of Mineral Resource And Cutoff Grade Optimization In Chalukou Molybdenum Deposit

With the popularity of digital technology,3D mining software is more and more used in mine project. Compared with traditional methods, it has many advantages in resource estimation, such as high speed of calculation, much more credible, and convenient to manage. These can greatly improve the efficiency of the operations. However, it also has some problems in practical, such as how to select the parameters in estimation, and how to achieve the classification of the resources and reserves, there are still not a fixed set of methods or processes to solve them. So when the engineers use geostatistics to evaluate the resources or reserves, they always feel helplessness.In order to solve these problems, and help the engineers use the software well, the paper took the ChaLuKou deposit as the example, and researched the methods and processes on how to select the parameters in estimation and achieving the classification of the resource and reserve in geostatistical software. According to the grade model which was built in3D mining software, the paper also studied how to choose the best cutoff grade of the project region.After the study, the problem of classification after resource estimate in the software was solved, it also provided a new method for the determination of the cutoff grade. The main content of the paper includes the following aspects:(1) By using the method of3D visualization, drilling hole database was built in the software, which was the basis of determining the mineralized zone as well as resource estimation;(2) The spatial variability of Mo grade in the composite sample was analysed, and a theoretical variogram was fitted by using spherical model; The Mo grade was transformed into indicated value using cutoff grade, as well as the spatial variability of the indicated value was analyzed. The Mo grade was estimated by using Ordinary Kriging and Indicator Kriging; and the tone-grade model of the deposit was built.(3) In this paper, geostatistical classification method of resources reserves and the relationship of the kriging variance,variogram, search ellipsoid, geological reliability was studied. Using geostatistics theory to determine the reasonable engineering interval in exploration, and using search ellipsoid sphere, minimum project number, minimum points to determine the estimated geological confidence was proposed. According to the latest classification criteria, the process of automatic classification of reserves in three-dimensional mining software was developed.(4) According to the result of resource estimation, the tone-grade model of the project region o was determined. Taking the technical and economic parameters into account, productivity, payback period, NPV and internal rate of return under a different cutoff grade were calculated. Then using the comprehensive evaluation method, the optimal cutoff grade in the project region was determined.