This week's photo from the past is part of the history of the Junction Reef Gold Mine, this article being part 3. The image shows a load of tunnel props are on two trolleys being hauled up the tramway.
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Miners had sunk shafts and adits to get down to the deeper gold bearing rock. These underground workings required solid timber props in the tunnels. The mine props were supplied to the mine head after they had been chopped down with an axe, then often cut to the required length with a two-man crosscut saw. It was hard backbreaking work for these contractors. The local pine timber was suitable as bulkheads and general stope support. As time went by vast quantities of timber were needed as props to support the ever-growing number of underground workings. As areas were denuded of suitable timber the woodmen would be on the lookout for new areas of mine quality wood.
Six buttresses had been constructed to support the five elliptical arches of the dam that had a span of 27 feet each with the designer insisting on a 60-degrees lean. An emergency overflow was located over each of the five arches. Originally a gated stepped natural rock cascade made up the dam's main spillway, that was built on the left bank.
The four Pelton wheels were supplied with water via the dam's hefty scour outlet tunnel that was protected as a safeguard by a gravel embankment. Finally, there was a fine screen that was inspected daily before the water entered the pipe inlet to supply hydropower for the mining company's machinery.
Whilst most gold mining companies used timber to fire their steam engines to supply much of their power to crush the ore into a fine powder with their heavy stamper the Junction Reefs Gold Mine utilised a large dam and hydroelectric equipment. Their various crushers and mills often ran six or more days a week, the monotonous and continual thumping sound heard around the countryside.
It seems that their silting problems began within the first decade of operations especially in the big floods in 1902. In 1930 another attempt was undertaken by engineers by using explosives to clear the scour tunnel, while it was partly successful the dam's original capacity was never attained again.
Ironically the Pelton wheels or Pelton turbines had been developed during the gold rush by Lester Allan Pelton in 1880 and was ideally suited to use to generate electricity in the Junction Reefs Gold Mine. Though there had been others who came up with the idea Pelton's was the most efficient design. Installing a hydroelectric plant meant that less firewood would be required and that was one of Oscar's aims to conserve natural resources where one could.
The water reservoir supplied the water to the concentration nozzles arranged around the turbine to force the water at a constant pressure onto the numerous cup shaped blades of the turbine. The blades were set out in pairs round the outside of the rim. To guarantee the pressure most hydroelectric plants had a surge tank fitted. The mine was fortunate to have electricity to power the steam driven winders that hauled the gold bearing ore to the surface and to feed the sulphide roasters processing the ore.
The Company's crushing mill was constructed using men paid by the day. More than forty worked under the watchful eye of Oscar himself. Two boilers were still required, and these were brought from another closed down mine near Orange by bullock teams. Processing the gold ore involved crushing the ore from the storage bins before it was sent to the leaching trays that involved using chlorine and cyanide.
It appears that the Australian Institute of Mining Engineers invited Oscar Schultz to present a paper on the dam he had designed and superintended for the Junction Reefs Gold Mine Company. Oscar explained his ideas very confidently as he detailed his theories and the progression of the ultimate dam scheme.
Oscar Schultz was certainly a talented and imaginative engineer who designed various bridges, it seems that he preferred projects where designers needed to think outside the box. The first Hawkesbury River Railway Bridge was a case in point when he worked as an engineer for the Union Bridge Company. He worked on many jobs that would allow him to use his ideas, many of which were ahead of the times.