The Application Of Geostatistics On 3-D Mineral Deposit Modeling

In this paper,I take Heilongjiang tongshan copper mine and Henan shangfanggou molybdenum mine as examples to detailedly discuss the application of geostatistics on three-dimensional mineral deposit modeling.Obtained results and knowledge are as follows:(1)This research combined with the actual business processes of mineral explor-ation and based on existing deposit modeling techniques,give a sophisticated mineral deposit modeling technology programs.The specific process is as follows:Building geology mineral resources information database based on the exploration and catalog standard;Building three-dimensional entity body of orebody and geological model;Creating empty cell block model with orebody entity model restriction;Analysing the regionalized variable,computing and fitting variograms,assigning cell blocks based on geostatistics and other statistics.(2)Taking Micormine as a software platform,the follow 3-D entity models were built:the fault,main altered rocks,? orebody,? orebody and?orebody in tongshan copper mine;the main geological body and orebody in shangfanggou molybdenum mine.(3)Before constructing geostatistics deposit model,the data preprocessing is taken.In this stage,special high-grade processing and samples combination are important.In this paper,the grade value at 97.5%of cumulative frequency curve are taken as the replace value for special high-grade.At the mean time,the length of samples combination was decided by the histogram of samples length.(4)By the histogram statistic method,we know that the distribution of Cu grade data in tongshan ? and ? orebody is skewed normal distribution,and the distribution of Cu grade data in tongshan?orebody is normal distribution,and the distribution of Mo grade data in shangfanggou orebody is not normal distribution.So according to these characteristics,I initially decide that ordinary kriging is used in tongshan copper mine,and the indicator kriging is used in shangfanggou molybdenum mine.(5)Experimental variogram of every orebody was computed,and then fitted to theoretical model.The crucial parameters of variogram:nugget,partial sill and range were obtained.In this process,when computing the omnidirectional variogram I found the ordinary kriging was indeed unfit for shangfanggou molybdenum mine.Meanwhile the indicator variogram is very good.So the indicator kriging was finally selected to be used in shangfangou.(6)Empty cell block model and search ellipse were built.The parameter setting of empty cell block and search ellipse affects the estimate accuracy.The cell block at margins of orebody was divided into smaller blocks to obtain more accurately volume.And the parameters of search ellipse must be set up according to the parameters of corresponding variogram.(7)The valuation model of ordinary kriging was built in tongshan copper mine.And the valuation model of indicator kriging was built in shangfanggou molybdenum mine.Finally the reserves of every orebody were calculated.