Talbot, JF & Burke, J 2013, 'Practical improvements to the shotcreting process at Lisheen Mine with particular attention to the mix design and admixture usage', in Y Potvin & B Brady (eds), Proceedings of the Seventh International Symposium on Ground Support in Mining and Underground Construction
, Australian Centre for Geomechanics, Perth, pp. 629-642.
The Lisheen Mine is a 1.4 mtpa underground zinc and lead operation located in Co. Tipperary, Ireland. The mine commenced production in 1999. In the six years between 2004 and 2010 the amount of sprayed concrete increased from 4,600 m³ per year to over 11,000 m³ per year. In 2009 a series of inefficiencies, which had developed in the overall shotcreting process, were identified. These included overuse of accelerator, high rebound, poor machine availability, inadequate spraying technique and generally suboptimal application which resulted in poor surface coverage, inadequate thickness and the need to respray.
In March 2010 a study was commenced to determine how to remedy these inefficiencies. The study focussed on the following areas:
The management element focussed mostly on planning and achieving maximum operator and spraying resources efficiency.
The mechanical aspect focussed on machine maintenance, availability, utilisation and downtime.
The quality assurance/mix design concentrated on a detailed view of all aspects of mix design with a view to improving initial set time, better cohesion and early strength development.
The operator training took the form of EFNARC sprayer training and certification which encouraged high quality application from the operators and adherence to the spraying procedure. In addition ground awareness and greater involvement by the shotcrete crew was used to motivate ownership of the operation.
As of November 2010 the efficiency of the spraying crew had improved by roughly 6%. The overall machine availability had increased by roughly 15%. Improvements in the mix design have given better adhesion, first pass thickness, better workability, and improved consistency in the mix and less rebound. The mine now has three qualified EFNARC sprayers who have demonstrated a measurable improvement in spraying technique.
This paper will outline the practical ways in which an operation can make significant improvements in its shotcrete process without disrupting day to day operations and ultimately produce a product that is of a very high standard.
Beauchamp, L.A. (2006) Ground Support Manual, Mines and Aggregates Safety and Health Association, Ontario, Canada.
EFNARC (2009) Efnarc nozzleman certification scheme course notes, EFNARC.
Melbye, T. (2006) Sprayed Concrete for Rock Support, UGC International User Manual, Switzerland.