Sinking Skilfully
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Sinking skilfully Publishing Date 30 Oct 2012 12:35pm GMT Author Summary Ed Northcote of Sinclair Knight Merz reviews three methods for vertical shaft sinking in mining, their advantages and disadvantages, plus the associated risks and costs A necessary early step in the study phase of any underground mining project is a review of how the ore is to be hauled to the surface. The decision on which method to use depends on the depth of the mine, tonnages to be hoisted, local topography, project and operational risks, capital and operating costs and the ability to maintain the system. The three most common haulage systems to transfer ore to the surface are trucking fleets, flights of conveyors and shaft hoisting systems. The first two haulage systems require a decline to be mined. Shaft haulage can be in a decline, but is more commonly via vertical access to the orebody. This article looks at vertical shaft sinking as an option and the three methods used to sink the shaft: raise bore, strip and line; blind sink; and Horidiam. When mine shafts are being considered, all too often the raise-bore, strip-and-line shaft-sinking method is adopted without exploring the alternatives. Understanding the shaft-sinking cycle and what occurs in each phase of the cycle provides further insight. Shaft sinking is rated as one of the highest-risk undertakings in the mining industry, not only from the point of view of safety of the shaft-sinking crews, but also from the point of view of risk to the project. A shaft-sinking operation in a greenfield site frequently falls on a project’s critical path. Mechanised shaft sinking uses raise- and blind-boring techniques – frequently for short (<500m deep) shafts. In competent ground, the finish of the shaft barrel can remain unlined. This allows shaft furniture to be bolted directly onto the country rock. In South Africa, this method has been very successful. For example, it has allowed a gold-mining company to drill a series of short-lift, small-diameter, raise-bored shafts equipped with Köepe winders, which were automated as elevators in buildings. This system improved the logistics for moving consumables and personnel to the internal levels of the mine and therefore improved productivity. Today, the raise and blind boring of shafts is a sophisticated process using dedicated machines, and this mechanised process will not be further addressed in this article as it deserves an article of its own. Raise bore, strip and line There are five phases in the raise-bore, strip-and-line shaft-sinking method (see Figure 1, page 60). The raise-bore phase requires different infrastructure from the shaft strip and line, and the equipment is again different in the operational phase of the shaft. It also needs access to the bottom of the shaft and, in the case of
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Transcript of Sinking Skilfully
Sinking skilfullyPublishing Date30 Oct 2012 12:35pm GMTAuthorSummaryEd Northcote of Sinclair Knight Merz reviews three methods for vertical shaft sinking in mining, their advantages and disadvantages, plus the associated risks and costsA necessary early step in the study phase of any underground mining project is a review of how the ore is to be hauled to the surface. The decision on which method to use depends on the depth of the mine, tonnages to be hoisted, local topography, project and operational risks, capital and operating costs and the ability to maintain the system.
The three most common haulage systems to transfer ore to the surface are trucking fleets, flights of conveyors and shaft hoisting systems. The first two haulage systems require a decline to be mined. Shaft haulage can be in a decline, but is more commonly via vertical access to the orebody.
This article looks at vertical shaft sinking as an option and the three methods used to sink the shaft: raise bore, strip and line; blind sink; and Horidiam.
When mine shafts are being considered, all too often the raise-bore, strip-and-line shaft-sinking method is adopted without exploring the alternatives. Understanding the shaft-sinking cycle and what occurs in each phase of the cycle provides further insight.
Shaft sinking is rated as one of the highest-risk undertakings in the mining industry, not only from the point of view of safety of the shaft-sinking crews, but also from the point of view of risk to the project. A shaft-sinking operation in a greenfield site frequently falls on a projects critical path.
Mechanised shaft sinking uses raise- and blind-boring techniques frequently for short (
