Mining Technology: Transactions of the Institutions of Mining and Metallurgy

The present paper provides a comprehensive approach to the use of simulations to determine sampling errors for three broad classifications of analyte characteristics: low concentrations of analyte mostly occluded within gangue grains, low concentrations of analyte occurring mainly as liberated grains and higher analyte concentrations. Poisson distributions are used for simulations for the first two of these classifications and a binomial distribution is used for the third. The methodology requires that samples are screened and each size fraction is weighed and assayed. Fortran computer codes and accompanying data sets are provided for each of the three classifications in the accompanying Appendixes. Outputs from the simulations are compared with the error variances generated by Gy's sampling formula.

This paper reviews the prevalent models for characterisation of goaf behaviour and their applicability for numerical modelling based estimation of stress recovery in typical strata conditions in Indian longwall mines. The work has been supplemented through a numerical modelling study incorporating a double yield model to assess its effectiveness in simulating the recovery of stress in the goaf. A digital photo analysis technique has been developed to characterise the goaf material. Based on findings of these studies, short and long term strategies are proposed for developing an improved model for a field representative estimation of stress–strain behaviour of the goaf material.

We provide a valuation framework for mining projects incorporating options to vary mining, processing and stockpiling rates, options to alter processing and stockpiling cutoff grades, options to expand mining and processing capacities and the option to abandon. Each of these real operating options is exercisable in response to price variability for the mineral being mined. With a case study application, we demonstrate that project optimisation with recognition of real options (versus without) entails: increased project value, as expected; and, at project outset, prescription of lower processing capacity (with lower associated capital expenditure), higher processing cutoff grade and greater use of stockpiles.

In recent decades, the effectiveness of royalties as a mechanism capable of capturing true economic rents is one of the most debatable issues for the mining industry worldwide. So far, the main interest in the literature lies in royalties as a form of mining taxation. This paper, however, focuses on the use of private royalties for the valuation of an aggregate quarry site, in Greece, which is made up of the value of the royalty income stream to the landowner. Defining a fair royalty for the seller as well as the purchaser was a mostly challenging issue, and although referred to as a specific case study, the analysis provides a useful insight for mining practitioners involved in quarry valuation.