How these Mines worked
Because of the complexities associated with extracting the gold-bearing wash that was situated well below ground-water level, the skilled miners of the Spring Hill and Berry deep leads had to develop new equipment and techniques to successfully work these mines. The techniques that were developed - which became known as the Ballarat System - occupies a unique position in Australia's mining history.
1.
Boilers, engines
and winding houses
Large boilers made of iron and up to 8m long and 2m in diameter generated the steam that powered the many engines at this mine.
Clean water was heated to boiling point by a wood fire within the cylindrical boilers and the pressurised steam created was then piped to the engines.
The engines were used to work the winding gear for the cages going up and down; for the air pumps that provided ventilation; for the puddling machines and for the pumps that cleared the water from the mine.
The Winding House was built immediately adjacent to the head frame so that the engine driver could see the cages as they reached the Landing Brace.
2.
Tramline and
mullock heap
The Mullock Heap (or dump) was a place where all the sand, sandstone, slate and clay that were not from the wash gutters were trucked and dumped.
Many of the mullock heaps in this district remain visible in some form today as the materials contained within are of no commercial value, however they remain of great historical importance and should
be protected and preserved.
3.
Head Frame
and Landing brace
Two sheave wheels, their steel cables leading back to the spool at the winding house, can be seen here at the top of the poppet head.
These wheels lowered and raised goods in the shaft. Shafts varied in size according to the mine’s needs and were sectioned into compartments for pumping water and air,
lifting and lowering miners, timbers and materials.
The Landing Brace, its access stairway and entrance door seen here, was where the ore trucks were manoeuvred from the shaft onto the tram rails.
4.
Puddling
Machines
All gravels and clays from the wash drives were trucked from the Landing Brace and tipped into huge elevated puddling tanks.
Water, pumped up from the mine, was added to the contents to assist the steam powered steel rakes that stirred and broke the clay away from the gravel. The clay, now suspended in the water, was drained and piped down to the Slime Dam.
The large cleaned quartz rocks were removed by hand using wide pronged forks and trucked off to the Wash Dump. This left only the fine gravels and the gold underneath which was removed through a trapdoor at the bottom of the puddler for further separation in the sluice.
5.
Slime Dam
and Wash Dump
Clay-laden water from the puddling machines, having been used to clean the gravel wash, was piped away from the mine to the Slime (or Slum) Dam which was originally enclosed by a wall of timber.
Over time the clayey water settled in the dam allowing the cleaner water to flow over the top and naturally down hill. Without the slime dam thousands of tonnes of clay would have blocked the natural tributaries.
The Wash Dump was where all the cleaned quartz from the puddling machines was dumped.
Almost all of the wash dumps on the goldfield have been reprocessed for commercial use. Those that remain must should be protected and preserved.
6.
Timber
Stockpile
The demand for timbers for building, burning and underground work created an industry in itself for the local millers and wagoners.
Forests of dense timber suited to heating the boilers were harvested at Koroocheang and Werona. The milled wood was transported by wagoners and their bullocks who passed through Smeaton on their way to the mines.
Straight strong structural timbers, used for propping and capping the drives to prevent collapse, were sourced from the Bullarook and Daylesford forests and in most cases delivered to Allendale by rail after 1887.
Each piece of timber was cut to a standard size depending on which area of the mine it was to be used.
Mining these Deep Leads required first the sinking of a shaft 1 through the basalt and ordovician slates and sandstones to a level below the ancient river beds 'wash gutter'.
From near the bottom of the shaft, a main reef drive 2
was excavated out and under the wash gutter 3 .
Drives were excavated so that all water would flow back to the sump in the shaft 4 where it was lifted to the surface by pumps. This also assisted hauling the ore trucks 5 back to the shaft as it was a 'downhill' run.
The clay, sand and slate that was removed from the drives remains on the surface today as 'mullock heaps'.
As the wash gutter 'leads' of the ancient rivers were well below the water table, they were saturated with pressurised water, which had to be drained before mining could commence.
Right: Cross section schematic diagram showing bores bleeding water from the wash gutter. Source: Deep Leads of Victoria. Institute of Engineers
To do this intermittent bore holes were drilled up into the lead from the drive below. These bores allowed miners to establish the position of the lead, gain indications of gold in the gutter and to 'bleed-off' the water at a controlled rate so the capacity of the pumps in the shaft was not exceeded.
In some mines pumping continued for years
before the wash gutter was drained enough to be entered
'Rises & shoots' 6 leading up and into the gutters were excavated to access the wash and as the lead was followed, a network of trucking and intermediate drives was created back to the shaft.
In order to extract the gold in the wash gutter, timber props, caps and laths were closely interlocked to form a 1.2m high enclosure. This dark timbered tunnel was the only protection the miners had from being suddenly engulfed by water, drift or falling rocks.
Right: Diagramatic representation of alluvial working on a large scale. Source: Deep Leads of Victoria. Institute of Engineers
The wash was precariously removed in 'blocks' at a time and the trucks of wash were hauled back to the shaft by pit ponies who were stabled underground.
The ore trucks were lifted up the shaft to the surface and onto the Landing Brace. The trucks were pushed along tramlines and emptied into the large iron tanks called puddlers where water and iron rakes broke off the clay and dirt to free the gold.
The large pieces of cleaned quartz were removed and trucked along the tramway to the wash dump and the clayey water was piped out to settle in the timber walled slime dam.
This left only the finer gravels which were run over sloping cloth tables, catching the gold, which was then taken to the gold room.
Right: The Landing Brace with trucks and tram line leading to the puddlers and mullock dump.
Chalks No. 1 Mine, Maryborough 1909
Cornish Beam Pump
Berry No. 1 & Hepburn Estate No.1 Mines, 1883
Cornish Beam Pumps were world famous for their power to lift water.
The two pump engines that were manufactured for this goldfield were the largest in the Southern Hemisphere.
“The exposed steelwork was ‘finished bright’ and there were numerous components of polished brass which would have made it a splendid looking machine”.
Annual Report of the Secretary of Mines, 1885
Above: Cross section of the Berry No. 1 Pump Engine based on Annual Report of the Secretary of Mines, 1885 and Rex Bridge’s 1883 model of the pump house which is displayed at the Creswick Visitor Information Centre. Drawing by Robt Haughie.
1. Pump Beam or ‘Bob’
At 10m long, 1.8m thick and weighing fifty tonnes, the massive beam transmitted the downward stroke of the engine’s piston, which in turn lifted the pump rod.
2. Gudgeon Pin
The gudgeon pin, on which the beam ‘bobbed’, weighed 3.5 tonnes and was made of hammered gun metal.
3. Pump Rod
The pump rod consisted of three sections of laminated oregon that were strapped and bolted together to make a single 180m+ length. The pump rod’s downwards plunge activated the three lift pumps in the shaft.
4. 'Bob' Wall
At ~1.8m thick, the bob wall supported the weight of the beam and the massive force
of its rocking motion.
5. Engine Cylinder
The engine weighed 10 tonnes and had a cylinder bore of ~1.8m in diameter. The engine could be set to operate from one to ten strokes per minute.
6. Eduction Pipes
These pipes transported the low-pressure steam out from the bottom of the piston as it was drawn into the condenser.
7. Condenser
The condenser sucked all the low-pressure steam from under the engine’s piston.
8. Lift Pumps
The three ~50cm lift pumps
were fixed vertically in the shaft ~61m apart.
Through an opened inlet valve, pressurised steam from the boiler enters the top part of the cylinder above the piston A , pushing it down, and the steam below the piston B is drawn into the condenser, creating a vacuum below the piston.
The pressure difference between the steam at boiler pressure above the piston and the vacuum below it pushes the piston and the beam end down – which in turn pulls the pump rod up.
Part way down the stroke, the pressurised steam inlet valve is closed. The steam above the piston then expands through the rest of the stroke, while the low-pressure steam on the bottom of the piston continues to be drawn into the condenser, thereby maintaining the partial vacuum in that part of the cylinder.
At the bottom of the stroke, the exhaust valve to the condenser is closed C and the equilibrium valve D is opened and the vacuum holding the piston is released.
This allowed the pumping rod to plunge under its own massive weight and activate the pumps in unison to push the water up a further 61m and finally to the surface.
As the piston comes up, steam is transferred through the equilibrium pipe E from above the piston to the bottom of the cylinder below the piston.
When the piston reaches the top of the cylinder, the cycle is ready to repeat.
Above: A plan section of Berry No.1’s ~6m x 4m shaft. Note the area or the winding shafts (1), used to raise and lower the cages, compared with what was required for the pump and cisterns (2). Source: Annual Report of the Secretary of Mines, 1885
Engine and pump components and how the pump worked
Brief geological history
During the Ordovician period (~450 million years ago) this area of Victoria was under a shallow sea and over time, layers of sand and mud hardened to form sedimentary rocks. Clay and mud formed mudstone and shale and sand formed sandstone. Pressure from geological forces caused these layers of rock to fold and break creating cracks called joints or faults.
About 400 million years ago, molten rock was pushed up (intruded) into these faults and without breaking the earth’s surface heated the sedimentary rocks to form metamorphic rocks.
Mudstone and shale became slate and sandstone liquified to become quartzite. The igneous molten rock never reached the surface and crystallised into granodiorite (granite).
Mineral-rich liquids later permeated into the Ordovician rocks under immense heat and pressure. This gold-bearing fluid was pushed into the cracks or faults where it crystalised and formed quartz veins (reefs) with gold.
About 200 million years ago, the Ordovician plateau, with its veins of gold-filled quartz, was crushed and carved by glaciers as they moved northward from the elevated surrounds of Ballarat.
Ancient rivers buried under lava
After the glacial periods, the crushed surface was subjected to rainfalls much stronger than those of today. Over time, the soft slates and sandstones were eroded down, granites exposed and the quartz reefs gradually weathered away releasing the gold within.
This alluvial gold, being heavier than rock, sank deep into the valleys and was washed into the creeks and rivers. As the river banks continued to erode and shift, the 'wash' became covered by layers of gravels (coarse drift), sands (fine drift), clays and layers of vegetation and fallen trees.
Several million years ago, molten rock (lava) in the form of basalt, made its way to the surface through vents in the earth. The pouring of lava from the surrounding volcanoes slowly covered the ancient rivers and valleys. In many places separate lava flows from separate volcanoes were layered one on top of the other to become over 150m thick.
The basaltic lava cooled entombing the ancient rivers and valleys, creating the undulating plains we see today. Here, well beneath the water table of the country, these ‘buried rivers of gold’, or as the miners called them 'deep leads', remained undiscovered until 1872.
