The Application Of Restricted Kriging In The Mineral Reserves Estimation

Reserves estimation is an important thing in geology mineral resource field, while geostatistics is one of the most effective tools for reserves estimation. It is a significance issue for geology works to improve the technology level of reserves estimation and its result's creditability and reliability. The research which is facing to the application of spatial 3D mineral resource modeling and reserves estimation, mainly base on two aspects: one is to interpret mineral correctly into solid model; the other one is to select the appropriate spatial interpolation methods in the process of reserves estimation, in the short time to complete accurate reserves estimation. With the update and development, geostatistics provides an path for resoling the questions.In the exploring of geology resource, there are kinds of estimation methods, for example Inverse Distant Weight, Section, Geostatistics and so on, it is more advance for geostatistics. In geostatistics, it is divided into ordinary kriging, cokriging, indicator kriging and restricted kriging and so on. Kriging is a most popular method in reserves estimation, and restricted kriging has obvious advantages, it can control the configuration of different sample values to reduce the effect for estimator which caused by smooth effect, is a bridge link between sample value and sample configuration.The article discusses the development situation of kriging method applied in reserves estimation, explains the theory of kriging mathematic model, which include regional variable, variogram, the determination of cutoff and the pre-probability, and it also describes the working steps and working flow which based on the software of Micromine, discusses the question of setting parameters and many problems to which we must pay attention.The article introduces some related conceptions about kriging, compares between different kriging methods and others (e.g. Inverse Distance Weight). From the point of ore type and ore form, analyzes the using range of kriging, provides a reference base for choosing appropriate methods in actual works.The emphases of this article is to study the application of kriging methods in actual mine reserves estimation, from the point of view of application, takes restricted kriging as an typical method, spreads the research on the various kriging methods. Most methods which concerned by this article is most basic and mature in geostatistics, the application has been discussed both in national and international magazines. But we still think that it is important to regard these methods as an effective solution by using clearly mathematic concept, combining with the requirement of reality produce, giving systemic, rigorous and concise discussion. The application of rigorous mathematic concepts and 3D visual geology software, which can enable us using mathematic model to solve reality works and get some new conclusions.(1) Chapter one is the fundament of geostatistics, discussing regional variable, covariance's conceptions and properties and their mathematic models. Deeply discussing the spherical model which is often used in actual works. In Chapter two, describing 5 kinds of Kriging methods strictly by the tools of matrix, probes into the theory and mathematic model of kriging, summarizes the meaning and the properties of various kriging methods.(2) Chapter three analyzes the mathematic meaning of restricted kriging, radically discovers its physical meaning. As a combination of ordinary kriging and indicator kriging, it links a bridge between data magnitude and data configuration, and can eliminate "smooth effect" which caused by ordinary kriging's property "weight independences its data values". Chapter four describes the using range of restricted kriging, analyze the effects which caused by different deposits. Giving the process of restricted kriging combined with actual examples, deeply discusses the mean that is how to determine the pre- probability of different grade segments.(3) Chapter five describing and analyzing the results by using different kriging, which provides a basis for finding most appropriate kriging method in reality works. Chapter six, in the platform of 3D visual geology software, discussing how to use the kriging methods and set the parameters in reality works.