The application of microcomputers in exploration and exploitation of mineral deposits

Computers& Gcasc~,ncesVol. 15. No. 4, pp. $87-~91,1989 Printed in Great Brittan. All nihts rc~-vod

0098-3004~89$3.GO+ 0.00 Copyrqjht 4~ 1989PeqpunonPros pk

THE APPLICATION OF MICROCOMPUTERS IN EXPLORATION A N D EXPLOITATION OF MINERAL DEPOSITS H. BURGER, C. KILqCH, and W. SKALA Geologischcs [nstitut der Freien Universitaet Berlin. Maltcscr Str. 74-100, 1000 Berlin 46. F.R.G. (Received 26 September 1986: receivedfor pubfication 24 September 1988) Abstract--The advent of powerful microcomputers has initiated the development of on-site workstations and the design of software packages for geological and mining applications. A field computer for application in exploration and exploitation of mineral deposits should be an easy-to-use hardware/software system which is capable of and can provide solutions for different problems. GPMicro. a geostatistical package for microcomputers, written in Pascal by members of the Mathematical Geology Working Group at the Frcc University of Berlin, provides basic calculations for a geostatistical study, for example "classical" statistics (histogram. scattergram), variogram calculations, two- and three-dimensional kriging. and display of kriging results. Key Wordv: Microcomputer, Geostatistics. Modular program package. INTRODUCTION During the past two decades mineral exploration has become more and more complex; the amount of data has increased considerably because of modern ,~tmpiing and analytical techniques; and sophisticated statistical and mathematical methods have been developed for the evaluation and mine planning of deposits. Concurrent with this development, computers have become a powerful tool for the interpretation of geological, geophysical, and geochemical data obtained in exploration programs throughout the world. Until a few years ago these data could be analyzed only by large computers with adequate storage and processing capacity. Today, the advent of powerful low-cost microcomputers has changed the situation completely. Small field computers with graphics capability enable the field geologist to ----collect data more efficiently and to develop alternative sampling patterns, -.--detect sampling errors and correct them as soon as possible, --facilitate the interpretation of spatial geological data. ---control and modify geological models of a mineral deposit using extensive computer graphics, --provide more reliable data and other information to the central computer of the mining company for final evaluation. --spend more time on geological interpretation of data than on hand-drawing ofisolines and profiles. Efficient use of field computers also will improve the productivity of a mine in all stages of development. GENERAL CONCEPTS AND REQUIREMENTS Design objectives In the first stage, a field computer should be an eAGIO lS:4-J

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easy-to-use hardware/software system which is capable of and can provide solutions for the following problems: ---collection and storage of all data (soil samples, drillholc data, etc.), --geostatistical analysis of these data (statistical parameters, histograms, variograms), --global and local reserve estimations with confidence levels, --graphical display of drillhole data, cross sections, and isoline maps on a terminal screen and plotter, --display of computational results in tables, curves, etc., on a matrix printer. In the second stage, the system should aid geological modeling of the deposit and mine planning. The on-site workstation The main reason for an on-site workstation is to enable the field geologist with little computer background to improve sampling and data analysis and facilitate decision making on-site. Growing experience with existing program packages and additional training will enable the operating geologist to adapt special programs and to interact with programmers or geostatisticians to modify local application software or select appropriate evaluation methodology. The hardware configuration of a system designed for exploration and mining applications must contain a microcomputer, which can perform numerical calculations within a reasonable time, has mass storage media capable of storing a large amount of data, complete with graphics display and output devices (Fig. 1). Because the CPU (central processing unit) of a computer is faster than other devices (tape, disk, floppies), the central memory of the system should be as large as possible (the usual memory size for micros

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Figure 1 llistogramofa¢cumuhttlonvalucs(thickncssgradeofphosphoritcs). range from 32 kbyte to I Mbyte. for minicomputers up to 4 Mbyte). Large data sets and programs can be stored on hard disks which are widespread for micros. In order to produce back-up copies of all data, software and the operating system, it is necessary to provide the system with an a&litional storage device (magnetic tape drive, streaming, or floppy disk drive). Elticient u ~ of interactive graphics requires a graphics terminal (b/w or color), a plotter, or printer with graphics capability in order to produce hard copy. GPMlcto---A GEOSTATISTICAL PACKAGE FOR MICROCOMPUTERS So]t,'are design The Geostatistical Package for Microcomputers (GPMicro) provides the basic calculations for a basic geostatistical study, for example "'classical" statistics (histograms, scattergrams), variogram calculation, kriging, and display of kriging results. The GPMicro has been written for a Hewlett-Packard series 200 microcomputer operating under the UCSD p-system. It was intended to make GPMicro as portable as possible; implementation on a larger system (HP series 500 under UNIX) indicates that this goal has been achieved. In order to obtain a high degree of portability, a widely used programming language, Pascal. was selected and all procedures depending on special hardware or operating system were included in separate modules outside the programs. Consequently, GPMicro can be implemented on most micro- and minicomputers with at least 256 kbyte or core memory, a graphics library, and a Pascal compiler. All programs have been written for interactive use, although they may run as batch jobs under a more sophisticated operating systems such as UNIX. To make working with the applications programs as easy as possible, they are organized hierarchically, the keyboard input is almost "goof proof". Thus the main

problem in Pascal that the program aborts if an illegal character has been input has been overcome. An online help facility also has been implemented, providing further reformation for the notice. To avoid different tile structures in each program, a unique file structure has been selected (FILE and REAL). As a "side effect" this file structure needs less space in massstorage media than usual ASCII files. A unique interface provides a data tn, nsfcr between the different programs and files. A skeleton for manipulating the different tiles (e.g. converting an ASCII file into a data tile) is provided in GPMicro The programs in GPMicro GPMicro consists basically of six different programs: (1) Statistics--"classicar' statistics and variogram calculation, (2) Trans--transformation of lognormal to normal data,

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ing, (5) Block--display of kriged blocks as block maps, (6) Isolin¢----display of kriged points as isolines. The Slatistics program calculates histograms (ordinary and cumulative), scattergrams, and variograms as well as displays the results either on the plotter or a

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graphics terminal (Figs. 2.4). Trans performs a 3-paramctric Iognormal transformation interactively. This is necessary if the data are not distributed suflicicntly normally. Adjust fits a variogram modcl to the experimental variogram calculated by Statistics (Fig. 5). The parameter of the model may be entered either by typing them in at the keyboard or by moving the cursor to the desired position (sill, range, slope, etc.) on the screen. The latter possibility depends on the graphics terminal used. If it does not provide a Iocator, this input method can be used. [ ~

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Krig2a13d gives an estimation of mean values of blocks or points by kriging. The variogram model obtained from Adjust and the block parameters have to be entered. Block mean values, block center values, the corresponding estimation error, and the number of samples used in the estimation procedure arc prin-

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clarations. This l i m i t a t i o n has b~en overcome in some

lsoline. Block mean valucs obtained by Krig2dI3d may be displayed by Block. Different shadings and colors for

programs by the use of pointers to array instead of simple arrays. Nevertheless. certain limitations on the number of samples are necessary. Currently, 400 samples may be used in Statistic.~ and Krig2a13d, 100 steps are allowed for the variogram calculation and a maximum of 2000 blocks/points may be estimated in Krig2dl3d. All calculations are performed in single precision, because not all Pascal compilers support double precision.

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each class of blocks offer nearly unlimitcd possibilities for thc generation of block maps. A classification of rcserves according to the GDMB-conventions (Wellmcr, 1983) can be obtained if desired (Fig. 8). isoline generates isolines for a regular grid obtained by Krig2al3d.

CONCLUSIONS

Limitations The available Pascal compiler did not support more than approximately 32kbyte of variable de-

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and the design of software packagcs for geological and mining applications.Increasing storage and computational capability as well as decreasing prices for the hardware components facilitatethe implementation of more sophisticatedalgorithms for sampling optimization, reserve estimation, and mine planning. The GPMicro, based on IBM compatible microcomputers, contains a set of program modules which supports the display and analysis of borehole data. Experience with this on-site workstation has shown that it will be possible to develop larger and more advanced programs on micros for investigation of multivariate data sets, alternative exploration strategies (Shulman, 1984; Shulman and Skala, 1985),

ultimate open-pit design, and economic evaluation of a mine.

REFERENCES

Shulman. M. L. 1984. Exploration strategy for phosphates in the Sinai Peninsula, Egypt: ISth Intern. Syrup.. APCOM. IMM, London. p. "/9-87. Shulman. M. J.. and Skala. W., 1985. Predictive assessment of regional potential in desert terrain: Proc. Prosp. in Areas of Desert Terrain (Rabat. Morocco). IMM. Lon. don. p. 59-70. Wcllmer. F.-W.. 1983. Klassification yon Lagerstaettenvor-

raeten rail Hilfe der Geostatistik: Schriftenreihe der GDMB. Heft 39.