The Chillagoe Smelters

The smelter site was chosen for its close proximity a reliable water supply and the Mungana group mines.
Note how the hill slope was put to good use.
Ore would arrive by rail at the top level (charge floor) where it was fed to the furnaces at the mid-level and released from the bottom the furnaces at ground level.

The main smelter chimney is the large chimney you see erected on the summit.
It is connected by a long brick and cement pipe (flue) to the furnace site which was cut into the hillside.
The overall height from the furnaces to the chimney is about 73 metres.

In front of the large chimney is the powerhouse chimney.

Many buildings and associated structures were constructed on site.
Although these no longer exist, various remains can be seen, including the stumps of administrative offices, the water softening plant, ice plant, the remains of the safe and two brick chimneys (the powerhouse and main smelter chimney).

Two blast furnaces were installed at Chillagoe in 1901, a third in 1907, and another in 1909.

Today, you can see remains of two of these blast furnaces.

Generally, the furnaces operated irregularly and far below capacity, and sometimes only one operated.
The greatest production occurred between 1907 and 1908.

A blast furnace consists of a tall, rectangular steel furnace, in which ore, fuel and flux are placed in alternate layers.
Compressed air is forced through a tuyere (opening) near the bottom of the furnace.
The material is fired for a few hours producing molten slag and matte (unrefined) copper which are then tapped from the bottom of the furnaces.

The Chillagoe furnaces probably held a charge of about 50 tonnes, of which about 10-15 tonnes would be fuel and flux and the rest ore (35-40 tonnes).

The product of each copper firing would be about 10 tonnes of matte, and 30 tonnes of slag.
Much material was lost as gas and dust up the flue.

Two-thirds of the ore smelted at Chillagoe came from the Girofla and Lady Jane Mines at Mungana.
The ore contained copper and lead mixed with sulphur and was pre-treated to lower the sulphur content.

Ore arrived by rail, was put into ore bins and crushed in the crushing plant.
It was then treated in the Huntington-Heberlein plant which combined the functions of roasting and smelting.
Crushed ore was mixed with local limestone and roasted for up to 12 hours in cone-shaped kettles to oxidise the sulphides.
It then went to a mechanical revolving furnace.
Because this plant never worked well, most of the lead smelting was actually done at the main smelter.

Following the poor performance of the Huntington-Heberlein plant, another roasting method was tried using the Dwight Lloyd sintering plant.
It operated from 1911-1933.

The Edwards roasters also prepared the ore for smelting by oxidising it to reduce the sulphide content.
They were an Australian invention, developed in Ballarat about 1897.

The converter is used for the last part of the copper smelting process.
The converter mixes molten copper matte from the blast furnace with silica to get rid of impurities.
A powerful air blast is blown through the mixture for about an hour until it is refined as copper metal.

The converter is a large steel container which can be rotated to different positions for filling, pouring slag, and pouring metal.
It has a lining of firebricks which are consumed in the reaction and have to be replaced regularly.

The products of the converter are slag and blister copper with a copper content of 99% or more. Blister copper requires further refining before it can be used commercially.

Two converters were installed at Chillagoe in 1903 and four more in 1907.
A larger blower was installed in 1909.
The converter plant operated until the smelter closed in 1943.

Slag is molten waste produced by chemical reactions in furnaces and converters during the smelting process.
Slag consists mainly of iron silicates.

While still liquid, slag was transported in pots mounted on a rail trolley and dumped.
As it cooled, it solidified into a hard black mass.
You can get an idea of the amount of slag produced by the smelting process.

It's an interesting place to dig around ....

Buildings - including the Dwight Lloyd sintering plant, stables, and other smelter buildings - were also built on the slag.

The smelter provided employment for up to 200 people when operating.
Working conditions were hot, smelly and hazardous.
Workers around the crushers or the charge floor spent their time in a haze of dust, and those who worked near roasters, furnaces, or converters constantly inhaled the bitter fumes of sulphur dioxide.

Common injuries included severed fingers (from handling heavy ore trucks, charge barrows, and slag pots) and burns caused by spills of smolten copper or slag.
Several workers died after falling into machinery or being crushed by ore trucks.

But by far the most serious and widespread problem facing the workers at Chillagoe was lead poisoning.
Two signs of very high levels of lead in the blood stream over a long time are blue discolouration of gums and weak wrists caused by wasting and paralysis of the forearm muscles.
These symptoms were very common in Chillagoe workers.