Visiting Chillagoe Smelters
The Chillagoe Smelters site is an excellent demonstration of the technology of mineral (copper, silver, lead and gold) smelting at the turn of the 20th century. An up-to-date plant was assembled and then modified repeatedly between 1901 and 1911 to meet local conditions. The physical remains at the Chillagoe Smelters preserve important evidence of historic smelting processes that are rare today.
Safety at the smelters
Chillagoe Smelters is an historical industrial site. Photo © Queensland Government.
The Chillagoe Smelters is an historical, industrial site that includes pits, tanks and contaminants. The site is a restricted access area and entry is prohibited. The area is unstable and contains asbestos and other toxic contaminants. Serious injury or death could result from entering these areas. For your safety, a restricted access area has been declared over the site.
- Observe the site from the viewing area. Do not enter the restricted access area.
- Never remove historical relics.
Observe the geological landscape at the Chillagoe smelters lookout. Photo © TTNQ
Chillagoe Smelters, Chillagoe-Mungana Caves National Park. Photo © Queensland Government.
The remains of the pre-treatment plant. Photo © Queensland Government.
From the car park and viewing point, three chimneys can be seen. From left to right they are the pre-treatment chimney, powerhouse chimney with the octagonal section, and the main smelter chimney on top of the hill.
The information below outlines the buildings and smelter process.
The ruin on the far right of the site is the assay office. Ore was tested for quality and content in a small laboratory at the assay office. The concrete bench, which provided a vibration-free base for weighing mineral samples, can still be seen.
The pre-treatment area is on the left near the pre-treatment chimney. This part of the smelters was built later than the main smelting plant as part of an ambitious expansion project in 1906–1907. The eight kettle Huntington-Herberlein plant, which roasted ore in large copper kettles, was the first to be installed. Later the Huntington-Herberlein plant was used in conjunction with an Edwards roaster, which consisted of a long steel oven, heated from beneath by a furnace. Ore was moved slowly through the oven by a series of mechanical paddles.
Both plants were inefficient and were replaced with two Dwight Lloyd sintering machines. These machines had a long, wide conveyor made of perforated, interlocking plates or pallets that carried the ore. Super-heated air was sucked through the perforated conveyor, roasting the ore. This pre-treatment process was effective due to the ore’s high sulfide content.
The slag heap is the large open area on the eastern (far) side of the site. The slag heap is an accumulation of waste produced by the smelting process. Horse-drawn trolleys pulled along tram lines carried millions of tonnes of slag to the heap. The top of the trolleys could be rotated so both pots of slag could be emptied.
If the trolleys were delayed the slag would solidify in the containers producing the solid bell-shaped plugs of slag that can be seen at the bottom of the heap. Trolley rail lines were re-positioned as the slag heap expanded.
As the ore extraction process was inefficient compared with today’s standards, a lot of heavy metals and minerals remained in the slag.
in 1983, local residents successfully campaigned to preserve the slag heap and associated structures as an historical site and tribute to the early settlers.
Offices and powerhouse
Stumps of the main office and the remains of the strong room (located at the rear of the office) can be seen to the south-west of the slag heap (in front of the octagonal powerhouse chimney).
The employees’ pay and gold produced by the smelters were stored in the strong room. With more than 400 employees at times, the payroll was often substantial.
A raised stone-pitched base can be seen beyond the office. Trade shops of carpenters, boilermakers, fitters, moulders and pattern makers once stood there.
Near the base of the octagonal powerhouse chimney were the boilers, powerhouse and blower room. The chimney produced a draft through the boilers that in turn generated steam. The steam was used to drive blowers for the blast furnaces and to power the electricity generators.
Underneath the main chimney are the remains of the two blast furnaces. The main body of the furnace had a double iron skin with a space between. Water flowed through the space to cool the inner skin and stop it melting. These two furnaces were used to produce copper matte. Charges of ore, fuel and flux were poured into the furnace from the charging floor, which was supported at about the level of the ’I’ beams, which can be seen at the top of the brick work. The large-diameter branching pipes to the left of the furnace stands are part of the ducting system where air was forced into the furnaces.
To the right of the furnace stands is the ‘gooseneck flue’, a large metal chimney that was once mounted above the steel hood at the top of the right hand furnace. Only two furnaces had this type of flue; this one and another further to the right. This variation in design is evidence of the experimentation and alteration of the plant carried out until about 1907.
Main flues and chimney
Most fumes from the furnaces were collected in the brick flue still visible along the rear of the building that ended at the main chimney. Other gases were withdrawn by overhead hoods and emitted into the atmosphere through the gooseneck flues.
The smelters were installed at the hill’s base and the chimney built on the summit, creating a 73m rise from the smelter floor to the chimney top. This produced an effective natural draught and was among many technical innovations at the smelters site.
Ore and coke bins
The hillside allowed materials to flow through the smelters by gravity. Ore was delivered by rail to bins on a platform behind the smelters and tipped into the furnaces. Coke (fuel for the smelting) was stored in two lines of bins at the rear.
An overhead crane carried a large crucible filled with molten matte copper from the furnaces to the converters. Molten material was poured into the upturned mouth of the converter. Tunnels allowed copper moulds, which were supported on small rail trolleys, to be moved behind the converter when they were full. This enabled the converter to be emptied in one continuous pour. It is believed that generally two converters were in use while others were being relined. The tunnels in the wall indicate where the converters were mounted.
- More information about the heritage of the Chillagoe Smelters.