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1 Datamine International, Units 9/10 Barclays Venture Centre, University of Warwick Science Park, Coventry CV4 7EZ, UK
2 ECC Ball Clays, 36 North Street, Wareham, Dorset BH20 4AW, UK
3 Datamine International, 1–2 Langham Place, London W1N 7DD, UK
This paper describes the use of an integrated software system in the evaluation of a layered Ball Clay deposit in the western part of the Hampshire Basin. The site has been investigated by core drilling over the past 15 years and very detailed lithological logs have been prepared together with a comprehensive set of physical and chemical test results.
A three-dimensional cellular block model was created using DATAMINE software to produce a seven layer model for the deposit. The main clay seam was divided into four horizons based on quality criteria and 14 different physical and chemical properties were interpolated into each of these layers. From this model, the reserves were then calculated on the basis of the proposed pit design. In addition, a series of grade plans were produced for seven of the more critical properties, together with contour and isopach maps of each clay horizon plus the sandy overburden. These plans may be used for the control of clay quality during production and for the prediction of changes in those clay properties which may affect product blending.
The structure and thickness of the basal non-productive clay sequence was also modelled in order to assess areas where this sequence is thin and susceptible to rupturing by high piezometric pressure in the underlying sand sequence. Isopachyte plans and cross sections were generated to demonstrate the variations in thickness of this sequence across the site.
This case history demonstrates the way in which a computer modelled database can be used to provide comprehensive structural interpretation, quality control and volumetric assessment of a bedded deposit with complex variation in both physical and chemical properties.
