|Mt Isa and Ballara||August 11 2021|
|Somewhat reluctantly we leave Gregory River.
To be honest we are probably leaving simply because we are restless. There is no logic involved. Perhaps there is no logic to any of our travels. Which with a bit of contemplation is good.
We traveled this road just a few months ago. Our detour through Camoweal.
We probably noticed the hills last time.
|Last time we turned right, the gravel road to Camooweal.
This time we head due south, on sealed road, towards the Barkly Highway.
|Constantly changing vegetation. The road edges changing from deep reds to pale.|
|The Barkly Highway was like any wide, sealed, main road,
We were quickly in Mt Isa.
|With traffic lights and other road furniture.|
|We'd driven 300km so opted for a long visit to the
supermarket, stock up with everything as the last big supermarket was
Katherine, before we headed west.
While packing the supplies away I bought a litre of automatic transmission fluid for the power steering reservoir. And a few litres of wine.
Then to the golf club, an overflow campsite for the town.
The train is of sulphuric acid tankers.
Mt Isa mines a copper iron sulphide ore which when roasted and smelted, to produce copper and slags containing iron, produces a heap of sulphur dioxide. A catalyst helps oxidise that to sulphur trioxide, which dissolved in water produces sulphuric acid.
The by-product is transported by rail to Phosphate Hill mine. Probably also to Townsville where the copper is shipped and refined electrolytically.
These are probably empty tankers returning to Mt Isa for the next load.
The copper ore body is below the lead - zinc - silver ore body which was the original reason for mining at Mt Isa.
An interesting combination. Unfortunate timing (a couple of wars and a depression) meant the mine wasn't as profitable as hoped and funds were short for a copper development.
|Mica Creek Power Station.
I think gas.
There is a pipeline, about 1,000km long, from Moomba, the large gas field way to the south.
Gas is also piped to the smelter. Like the railway the pipeline has junctions to other mines such as Cannington and Phosphate Hill.
|The Golf Club suits our purpose. A few other campers, this
weekend is the Mt Isa Rodeo.
Sadly the town isn't as busy as hoped for due to various covid-19 lockdowns and other restrictions.
For some reason my bias against pigeons, which in the past I've seen only as a nuisance in public places, has coloured my perceptions.
To make amends. A unidentified variety of pigeon.
The golf course has very green grass. The surrounding area spinifex. The campsite dust.
|Our main purpose is to visit the Riversleigh Fossil Centre.
Sadly, I mistimed booking. Nothing left today, we are booked for tomorrow.
So we drive east, for about 60km, to the Ballara Mining Trail. A bit of a tour through an old, mostly abandoned, mining area.
|Copper smelter slag.
Slag that has gone solid in the bottom of the slag ladle.
A relatively small operation by current standards.
|Not much remaining of the smelter at Bulonga.
Foundations, slag heap, and a few refractory bricks.
The smelter equipment was mostly sold when it closed.
|Top of the slag heap.
The slag ladles were wheeled to the edge and the molten contents tipped out.
In 1906 a tunnel showed ore with copper at 2.5 to 9%. Very rich by today's standards.
The Corella Smelter treated ores from several mines in the area, including the adjacent Rosebud Mine.
|The face of the slag heap.
We missed the vehicle track to the top and approached from the Rosebud Weir and climbed up. The shape of the slag heap unmistakeable.
|The mine had a bit of a problem with water inundation.
A weir was built on the Corella Creek. To control water and supply the town of Bulonga.
1916 smelter operations suspended due to lack of water.
1917 Rosebud Mine inundated with water.
Last firing of the smelter in June 1917.
Between 1915 and 1917 24,000 tonnes of ore at 5 - 6% copper processed. About 600 tonnes of copper per year. A small operation.
Time to mention I once worked in a Zambian copper smelter. Many times larger, just as Mt Isa is.
The ore underground is copper iron sulphide.
Near the surface it can become oxidised. So we see some malachite, a semi precious variety of copper oxide.
|Lady Jenny project. There was a big sign later.
We explored a side road and figured someone was doing a bit of prospecting.
|A bit further south was Ballara. Surveyed in 1913.
A major (for the time) rail junction once it was decided Hightville was unsuitable.
The 2 foot gauge line to Wee McGregor met the larger 3 foot 6 inch gauge north south line.
The 3 foot 6 line came from the south. From MacGregor Junction, near Malbon.
I don't have a map of the lines available but imagine an extensive network feeding smelters.
|Not the police station, but in 1924 that was moved to Mt
Isa where the need was apparently greater.
The buildings were "demountable". Of a size that could be taken apart and moved.
Most likely the station manager's house.
|Post WWI the price of copper fell. The smelter Kuridala, to
the east, closed in 1920.
The MacGregor mining field also then closed.
The hills surrounding Ballara look fascinating.
A quartz wall occupies one of the hills.
It seems the wider gauge line ran to Kuridala, about 70km south east, to a smelter.
We have a general sense we could spend a lot of time around Mt Isa / Cloncurry. But for no real reason will head south.
|At Fountain Spring the gossens (oxidised outcrops) are
obvious. We've seen them throughout the Mt Isa region.
There is high grade iron ore (magnetite like we saw mined in Sweden) in the area. Useful in the copper smelting process for maintaining slag chemistry (so it melts at normal smelting temperatures) but not the best.
Higher grade than in the Pilbara but presumably insufficient quantities to be economic.
|Water in the pool at Fountain Spring.
A bit late in the year, just a trickle so the pool is not perhaps as welcoming for a swim as at other times. ......
|Back through Ballara, turn west towards Hightville.
This is the ore transfer station. Ore in 5 tonne hopper wagons from the very narrow gauge on the upper level was tipped into 20 tonne wagons on the wider gauge line below.
The ore was from the Wee McGregor Mine.
I can count 12 mines marked on the current map of this, the MacGregor mine field. And know of at least three that are not marked. Many more to the south and east. I lost count. And of course Mt Isa to the west. A busy place in its time. So many fortunes, so many abandoned hopes.
I was surprised at how small.
Hightville was unsuitable as a rail terminal, so everyone moved to Ballara.
|This is described as "hard core 4wd".
Just a bit stony. Though the difference in level of the two wheels may have caused us to tilt more than we are comfortable with (we give up before the truck does).
We could have turned around and parked just before this.
We actually stopped at the Hightville sign, some 600m earlier, in deference to the information provided.
Bah humbug - could have saved a walk of 600m. We must be feeling our age - though we enjoyed the walk as we see more than when driving.
Its a cutting that carried the 2 foot gauge rail line.
The total length of the line is 6.1km.
|To the tunnel.
The only rail tunnel west of the dividing range in Queensland.
I expected a tunnel that carried a 2 foot gauge line to be narrow and not very tall.
I walked through with more than a metre of head room.
77 yards long. Hewn by hand.
|The eastern portal.|
|Looking west at the Wee McGregor Mine.
The pick of the bunch of three mines served by the line.
We were feeling a bit lacadaisical so didn't attempt the vehicle track that seemed to run over a pass to the mine.
|On the way back we took more interest in bridge abutments,
like this one, cuttings, and embankments.
The line may have been narrow, but it needed some serious engineering.
|The hills are just asking to be prospected.|
|Riversleigh Fossil Centre||August 13 2021|