Technical and operational aspects of tunnel rounds in artisanal underground mining

Abstract

In the world today, due to the current high price of gold, thousands of artisanal small-scale mines operate without the financial or technical capacity to upgrade their production methods, often using equipment and working methods that were forsaken decades ago in the conventional mining industry. This article illustrates, with a practical example, that it is possible to achieve the modern requirements of quality, safety and productivity, while operating with mining equipment that basically possesses the same characteristics as that employed in the 1950s. The operation involved the excavation of a 6 meter long tunnel and over 25 stoping sections in both rock and concrete by drilling and blasting in an underground gold mine. The article describes how the main operational problems were overcome. An effective drilling pattern was designed in order to be easily achievable with the limited local equipment. The behavior of the local nitrate explosive was effectively predicted and managed. The interaction with the drilling teams was managed in order to determine a meeting point between their traditional working methods and the scientific view of the engineer. At the end of the article some general guidelines are proposed for the management of similar situations, in order to improve the efficiency, productivity and safety of drill and blast operations in small-scale mines.

Socio-environmental conflicts resulting from extractive activities in Latin America and Corporate Social Responsibility

“…Hence, health problems arise due to their intense labor, a reduced technological implementation and a high level of informality due to the national juridical framework. These conditions support the need to invest in promoting responsible and sustainable activities that provide a good quality of life to both miners and their families (Seccatore, Magny & De Tomi, 2014). In parallel, for 90 years, gold extraction has been the leading promoter of economic activity in the Portovelo and Zaruma regions (Ecuador).…”

Peculiarities of drilling and blasting in underground small-scale mines

“…• Clean contour • Fine and uniform granulometry The mine studied in Ecuador, Golden Minera Comunitaria, is located in the Zaruma-Portovelo mining district, in the province of El Oro, southern Ecuador. Technical aspects of drilling and blasting in these mines have already been documented by Seccatore et al 2014b. Other economic and strategic aspects of the mines of this area are described in detail in Seccatore et al, 2013and Marin et al, 2016and Sandoval, 2001.…”

“…The ASM way of working lacks an early exploration, feasibility studies and any kind of planning Echavarría, 2011, Seccatore et al, 2013). Likewise, the methodologies, tools and technological applications of ASMs are often very outdated, obsolete, inefficient and unsafe most of the time because they are applied incorrectly (see Seccatore et al 2014b). The line of work of underground ASM in the Andes region is basically based on drilling and blasting, and then, loading and transportation.…”

“…Local miners typically employ a column charge of hand-made cartridges of Ammonium Nitrate (AN, without Fuel Oil, in drills: This is because the ventilation time decreases and, despite having a lower VOD, the shock wave manages to fracture the rock; detail in Seccatore et al 2014b) rolled in newspaper foils, boosted by one cartridge of Dynamite 60% NGL as bottom charge, in its turned primed by a fire cap n.8. The good fragmentation obtained suggests that AN detonates when ignited by dynamite.…”