Improved IDW method for ore grade estimation based on spatial variation

Abstract：Aiming at the inverse distance weighting（IDW） method for ore grade estimation,we improved the original IDW method.Spatial variation of grade values belong to the sample data was analyzed with geostatistic variogram theory.According to the shape of ore body,three dimensional variogram models in the direction of strike,dip and thickness were calculated.And then these three directions and range values of variogram models were used to define the parameters of search ellipsoid.An octant searching scheme with constraint of sample count in per octant was carried out for reducing clustering effects of the sample data.On the basis of the density of exploration grid,the search area and number of drill hole were considered to classify the resource and ore reserve.This method was implemented by using C＋＋language on the Hoops platform for three dimensional visualization.The workflow of the ore grade estimation using this improved IDW method was summarized by the example of a copper mine.The results show that this improved method is simple and effective.Moreover,it can produce good ore grade estimation.