Ottery Mine is a heritage-listed former mine located 8 km north-east of Emmaville, Glen Innes Severn, New South Wales, Australia. It was built from 1882 to 1939. The property is owned by the New South Wales Department of Primary Industries. It was added to the New South Wales State Heritage Register on 2 April 1999.
History
The Ottery Mine is a derelict underground tin/arsenic mine located 8 km northeast of Emmaville in far northern New South Wales. It was one of the first underground base metal deposits exploited in the Emmaville district and lies about 2.5 km north of the old mining village of Tent Hill.
The mine was discovered by and named after Alexander Ottery in the late 1870s. It was worked continuously for tin between 1882 and 1905 by the Glen Smelting Company who set up a 15 head stamper battery at near by Tent Hill. Extensive mine developments occurred with eight shafts being sunk and 2,500 tonnes of tin concentrate being produced. As the lode became deeper the sulphide content became higher and a smelter was erected on site to calcine the ore. After it was fired the ore was transported to Tent Hill for crushing. After a fatal accident in 1906, operations ceased and did not begin again until 1920 when the mine was acquired by the Sydney based William Cooper and Nephews (Aust.) Pty. Ltd. Their sole purpose was to produce arsenic for sheep and cattle dips and other pesticides. An on site ore processing plant was constructed under the supervision of mine manager A. C. Julius and production of the 99.7% pure arsenic trioxide began in 1921.
The process of arsenic extraction involved feeding the coarse ore into roasting kilns and the fine ore into a mechanical furnace for firing. The resulting arsenic fumes passed into a set of 66 condensation chambers where the gasses were cooled and sublimed onto the interior brickwork as solid crystals of crude arsenic trioxide. The crystals were further refined by being re-fired and the gasses re-sublimed. The concentrated arsenic trioxide was then barrelled and transported to Sydney.
From 1925 to 1927 a ten-head stamper battery, grinding pans, concentrating tables, a concrete weir and pump were installed to extract the tin that was also present in the arsenic ores. The plant reworked arsenic tailings as well as some high tin, low arsenic ores. Operations ceased in late 1929 due to the economic depression and low mineral prices, only to reopen again in 1931. It operated in a limited capacity until 1936 when it was forced to close due to the importation of cheaper arsenic.
Burma Malay Tin Ltd. purchased the Ottery and commenced operations in June 1938. The company imported flotation equipment and constructed a freshwater dam for the storage of boiler feed and dressing water. No arsenic production occurred at this time. Prolonged dry weather forced the close of operations in 1940 and the company pulled down the plant buildings and equipment and transferred them to other sites.
From 1956-7 the Guardian Trading and Investment Company Pty. Ltd. reconditioned the mill and set up equipment to treat the remains of the old calcine dump. Further minor attempts were made to mine and treat the dumps but no further major mining operations were established.
In 1993 Ottery was rehabilitated in a joint project by the Department of Conservation and Land Management and the Department of Mineral Resources. This included: reducing the pollution of contaminated water/sediments in the area; improving fencing around the structures, many of which were unstable; fencing and covering open shafts and erecting walkways and viewing platforms.
Description
The total site covers some 20 hectares, although the PCO curtilage is confined to the area immediately surrounding the main buildings and works. The Ottery mine workings lie on the side of a steep hill at the head of a narrow gully. All drainage from the gully flows into a small, unnamed ephemeral creek. Numerous derelict structures, open mine workings, eroding slimes dams, spoil heaps and pieces of machinery are scattered across the site. These include the primary kilns, the secondary kilns, the rotary kiln, refinery, cooperage and two twin banks of condensers leading up the hill to a common flue and chimney. The chimney stack still in excellent condition, dominates the crest of the hill.