Software assisted bench blast optimization

Blasting activities in mines and quarries have been placing significant emphasis on the ability to tailor fragmentation to improve downstream process. Achieving the optimum blast design for a particular rock mass type can be an expensive and time consuming procedure. Also in many of these operations, the impact of fines and blast design has been clearly identified. The need to be able to predict the degree of fines from blasting has driven the development of an improved engineering model. Over the past few years, many countries such as Australia, USA, Canada, UK and Russia have been using Numerical Modeling softwares for optimize bench blast designing. However, in Sri Lanka up to now, these methods are not being used. In Sri Lanka, ordinary blasting techniques which are based on past experience are practiced. The outcome of this study shows that bench blasting operations can be optimized by means of JKSimBlast software

Biological activity in metal-contaminated calcareous agricultural soils: the role of the organic matter composition and the particle size distribution

Organic matter (OM) plays a key role in microbial response to soil metal contamination, yet little is known about how the composition of the OM affects this response in Mediterranean calcareous agricultural soils. A set of Mediterranean soils, with different contents and compositions of OM and carbonate and fine mineral fractions, was spiked with a mixture of Cd, Cu, Pb, and Zn and incubated for 12 months for aging. Microbial (Biolog Ecoplates) and enzyme activities (dehydrogenase, DHA; β-galactosidase, BGAL; phosphatase, PHOS; and urease, URE) were assessed and related to metal availability and soil physicochemical parameters. All enzyme activities decreased significantly with metal contamination 36-68 % (DHA), 24-85 % (BGAL), 22-72 % (PHOS), and 14-84 % (URE) inhibitions. Similarly, catabolic activity was negatively affected, especially phenol catabolism (~86 % compared to 25-55 % inhibition for the rest of the substrates). Catabolic and DHA activities were negatively correlated with ethylenediaminetetraacetic acid (EDTA)-extractable Cd and Pb, but positively with CaCl2, NaNO3, and DTPA-extractable Cu and Zn. Soluble OM (water- and hot-water-soluble organic C) was positively related to enzyme and catabolic activities. Recalcitrant OM and fine mineral fractions were positively related to BGAL and PHOS. Conversely, catabolic activity was negatively related to clay and positively to silt and labile OM. Results indicate that the microbial response to metal contamination is highly affected by texture and OM composition. © 2014 Springer-Verlag Berlin Heidelberg