Title: Hydraulic coal mining developments in New Zealand
Abstract: Hydraulic transport of coal has been used for many years on the West Coast of New Zealand to extract small blocks of steeply dipping coal. Recent development at Strongman 2 Mine has seen the use of high pressure monitors to cut coal and a corresponding increase in the scale of production. This paper provides a brief introduction to hydraulic mining, describes the present system used at Strongman 2 and discusses future potential development. HYDRAULIC EXTRACTION OF COAL IN NEW ZEALAND The use of water for the transport of coal underground is recorded as far back as 1927. It became the method of choice for small private operations on the West Coast of the South Island, as it required very little capital investment and allowed small, steeply dipping blocks of coal to be mined competitively with the larger State owned conventional operations. Eventually as pressure on production cost increased and some union resistance was overcome, larger State operations such as Strongman (opened 1939) came to utilise hydraulic transport. This was generally from the face to an underground dewatering station followed by conventional transport to the surface. The use of large centrifugal pumps to complete the slurry journey to the surface also became common practice. These operations were handicapped by the need for shotfIring to break the coal, the need for numerous production places and the extraction requirements of old workings laid out for conventional haulage, often with many collapsed roadways. Hydraulic transport allowed narrow splits to be driven through pillars in these fallen panels, enabling reasonably safe extraction to be carried out with good recovery ratios. To trial monitor extraction a system was installed at the established Strongman Mine in 1992, utilising two high pressure pumps, a 200mm high pressure pipeline and monitor face units which had become surplus with the closure of Sunagawa Mine in Japan. Extraction by monitor of old workings in Panel 3 and the Main East Headings was completed in 1994 and the mine closed. The trial showed that the hard Strongman type coal could be cut successfully, particularly where significant roof weight was present, and the generally hard roof and floor resulted in high seam recovery and little floor contamination. Previous shotfIring extraction had resulted in a number of goaf fIres as small coal was often left behind after pillar falls. No sign of spontaneous combustion occurred during monitor extraction, due to the washing of fine coal from the goaf, the better recovery achieved, and the quick retreat rate. While further drilling was carried out on the main Greymouth Coalfield, a smaller block of coal was identified to the east of Strongman Mine and the Strongman 2 Mine was established. The position of the Strongman Mine and the Greymouth Coalfield is shown in Fig.1 1 Strongman 2 Mine Manager, Solid Energy New Zealand Ltd, Greymouth COAL98 Conference WoUongong 1820 February 1998 333
Publication Year: 1998
Publication Date: 1998-01-01
Language: en
Type: article
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Cited By Count: 1
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