Geostatistical Framework for Modelling Clay Deposits: Nova Veneza Case Study in Southern Brazil

Abstract

The region of Criciúma, Southern Brazil, is known as one of the main ceramic industrial districts in the world. Clay minerals are one of the key ingredients in the ceramic industry. Clay characteristics including several physical and chemical parameters need to be known throughout the entire deposit to help in defining the mining plan, scheduling and blending strategies.

This paper proposes a geostatistical framework to model two essential clay properties required to be controlled in the ceramic industrial process, respectively water absorption and linear retraction. The methodology proposed is illustrated in a deposit consisting of two sedimentary systems conditioned by tectonic structures. These structures define two anisotropy systems interacting and affecting the spatial continuity of the parameters studied. Geological, topographical and geomorphological mapping were followed by geostatistical evaluation. Two distinct geological domains were defined, resulting in two sub-datasets. Samples available from auger holes were logged and analysed at different lengths (support), requiring the use of accumulations to overcome the problem caused by multiple sample supports.

Ordinary kriging was selected to estimate 25 x 25m blocks and stochastic simulation was used to assess the variability of the thickness values assigned to each block. Risk on recoverable reserves was quantified. The results obtained encourage the application of the proposed methodology as they proved to be more efficient than traditional evaluation methods.