Abstract Radial basis functions can be used as an alternative method for mineral resource estimation when ordinary kriging cannot be done because it is impossible to calculate an experimental variogram. Interpolation based on radial based functions is a method that is similar to ordinary kriging. In this context, this article presents the results of gold resource estimation and modeling of the União Luis and Morro do Carrapato gold deposits located in Alta Floresta Gold Province, Mato Grosso. Experimental variograms in the main direction (90-degree strike) resulted in a pure nugget effect, whereas in the orthogonal direction (180/85), they resulted in a structured variogram. However, the structured variogram for 180/85 is useless because three orthogonal variograms are needed to define the anisotropy ellipsoid for deriving a correlation model used in ordinary kriging. Thus, mineral resource estimation was done using multiquadric equations, a very popular radial based function kernel. The 3D model for gold grades showed a vertical distribution suggesting a structural conditioning for gold mineralization. The grade-tonnage curve with a simulated cutoff of 5.0 g/ton resulted in a gold mineral resource of 2.122 tons. Through the above, the gold estimation and multiquadric equation-based 3D model for the studied area can be considered effective in its objective to estimate ore resources from the available data.

Abstract Estimating mineral resources of a stratiform mineral deposit is not always a simple activity. Some difficulties can arise in mineral deposits where the thickness is relatively much smaller than the dimensions in the horizontal plane, or because these deposits have suffered events after their genesis, such as thrusts and folds. Usually, in these cases, we use a new variable named accumulation as a product between the average grade and thickness. Then, from these service variables, accumulation and thickness are estimated in a regular grid. Dividing accumulation by thickness, we have the mean grade. However, the mean grade is just an approach because the uncertainties of variables are not considered in this division. This calls for applying the Taylor series to computing, not only the mean grade, but also the associated uncertainty. In this article, we present the satisfactory results of this method applied to quantify the mean grades and uncertainties of the blocks to a stratiform phosphate deposit located in southern Mato Grosso, Brazil.

The capacity of natural zeolites and its host rock (dacite) to remove Pb2+ and Cr3+ from aqueous solutions has been investigated. Results showed that both samples prefer to remove Pb2+ instead of Cr3+. Almost 100% of Pb2+ was removed from solutions with concentration until 50 mg L-1 and 100 mg L-1 of this metal, respectively by dacite and zeolite. The equilibrium of metals adsorption process was reached during the first 30 min by both materials. Na+ can be used to recover Pb2+, but not to remove Cr3+ from the treated samples. The Sips model showed a good fit for experimental data of this study.