Gold dredges development


Category
Engineering Work (eg road, bridge, sawmill, dam)

Description
Gold winning by bucket dredge is a New Zealand development which began in Otago

By means of dredges, which were first used for winning gold in New Zealand, wash-dirt was obtained from the beds of large rivers. The earliest “spoon-dredges” were employed in 1863 and for a time they won a considerable amount of gold with very simple appliances. Five years later the bucket type of dredge was introduced, and this, in various forms, has been used ever since. Important changes however, have been the introduction of steam dredges about 1882, and electric dredges in 1890, and the accidental but very profitable discovery at the very end of the century, that often there were rich gold-bearing deposits concealed beneath a hard layer which was apparently the bottom of the river bed.

The first successful gold dredge was commissioned through the vision and perseverance of Sew Hoy (Sew Hoy Big Beach Mining Co) and was built by Kincaid & McQueen, Dunedin.

Both the first electric dredge and also the first one to be electrically-operated from a 3-phase alternating current supply were built and operated in New Zealand.

The former of these, “The Sandhills Dredge” – was designed and put into operation in 1889-90 by R.C. Jones who later became one of the founders of the firm Turnbull & Jones. This dredge operated on the Upper Shotover River, Central Otago, power being supplied at 1300 volts to operate the plant on what proved to be the first electrically operated gold dredge in the world. The dredge was a complete success, the electrical equipment performing its work faithfully.

This success was followed several years later by another pioneer – “The Fourteen Mile Beach Dredge” – which was the first electrically-operated dredge in the world driven by a three-phase alternating current supply.

By 1900 there were 187 dredges at work among the gravels of the Clutha. It is said to have been the greatest assembly of gold dredges the world has ever seen. In the boom period of dredging, about that time, efficient dredges secured as much as 1000 ounces of gold in one week’s working.

Only a few years ago the Kanieri, the last of the 150 gold dredges that worked the West Coast, was still operating on the Taramakau River. Gravel scooped up by a chain of buckets was washed over sluice boxes and gold tables and the waste or tailings deposited at the rear of the dredge, something that environmentalists would not tolerate today.

Patearoa, 17 km south of Ranfurly, had its goldrush in the early 1860s. One of the few relics from those days is a dredge which was operated from a barge on the nearby Taieri River in 1896. It was abandoned and became partly submerged in the river, but was salvaged and restored in 1978 for display in the town.

The dredge buckets in Cromwell Town Centre, Cromwell represented the development of bucket dredging from the “Shine No 1” in 1900, to one of the world’s largest, the “Austral Malay” in 1940.


Heritage recognition
IPENZ “Engineering to 1990” project
This item of New Zealand’s engineering heritage was recognised as part of the IPENZ “Engineering to 1990” project which the Institution organised to help celebrate the country’s sesquicentenary in 1990. A plaque was unveiled to mark the significance of the gold dredges developed in this country as part of the development of the nation.


Attachments

THE DEVELOPMENT DREDGES AND DREDGING TECHNIQUES.pdf

Location
Cromwell Town Centre, Cromwell

Region/s
Nelson Bays, Otago, West Coast/Buller

Access Info
The dredge buckets are available for viewing at all times.

Nature of Engineering
Manufacturing and Industrial Processing

 

Gold dredging in the Clutha River. Ref: 1/2-019707-F. Alexander Turnbull Library, Wellington, New Zealand. http://beta.natlib.govt.nz/records/23224242

(Click image to enlarge )

Dredging a river for gold near Lowburn. Ref: 1/2-018331-F. Alexander Turnbull Library, Wellington, New Zealand. http://beta.natlib.govt.nz/records/22896177

(Click image to enlarge )