Gold digger

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Sketch of a simple, open gold excavator ( EB , 1911)

A gold excavator ( English gold dredge ) is a dredger (Dredging) with integrated treatment system , used for the washing of gold from alluvial deposits , d. H. from alluvial subsoil ( fluvial sediments , debris , gravel , sand , mud ) in the bed or bank area of a gold-bearing body of water.

Such excavators experienced their heyday in the early 20th century in continuation of the gold rush era of the 19th century, when the laborious manual work of thousands of gold miners was increasingly supported by powerful machines as part of industrialization . With declining yields and prices, the large excavators largely disappeared from the former gold regions of western North America in the middle of the 20th century, but they are still used in various sizes in other countries around the world.

In addition to gold, similar soap dredgers are also used to extract other metals (or ores ), minerals and gemstones (especially diamonds ), which occur in concentrations that are worth building in some soap deposits . Among the metals, tin (mostly as cassiterite ) should be mentioned in particular , but also titanium (mostly as ilmenite or rutile ), zircon , tungsten , platinum and various others.

technology

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  Excavator in the Sumpter Valley, Oregon, USA

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  Detail of a chain of buckets

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  Detail of the stacker boom

Structure and functionality

A dredger is mounted on a pontoon for its floating use . Since the excavator hardly moves forwards during its work, it does not have a streamlined ship shape, but rather a rectangular, function-oriented floor plan. Typically, the dredger is given a weatherproof cover so that it looks more like a floating factory building than a ship. The excavator does not have its own drive for movement either, but is pulled. In the first gold excavators, the machines inside were driven by steam engines , and later by electric or combustion engines . In rare cases, when used in flowing water with sufficient current, the machine was driven by water wheels attached to the side of the excavator , similar to a ship mill .

The gold excavator has the actual excavator on the front to continuously convey the aluvial material. The classic construction is a bucket chain excavator . Recently, smaller suction dredgers (often with a cutting head ) have been used instead of bucket chain dredgers .

The excavator throws the material directly into a processing plant, consisting of a sieve drum for pre-sorting and one or more washing troughs or other sifters for separating the gold.

After the gold has been separated, the washed-out material ( wash mountains , tailings , waste) is ejected again at the rear of the excavator with a spreader with a long boom. The coarse rubble from the drum is usually deposited separately from the fine fraction, but mixing it up promotes rapid recultivation .

Operational environment

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  Typical gold deposits in river soaps

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  Thawing the permafrost in the run-up to the excavator using steam

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  Typical “crocodiles” left behind by a gold digger

The gold in soap deposits originally comes from primary deposits , which are mainly found in tectonically and hydrothermally very active zones of the earth. The weathering products of such deposits in the mountains are washed out by water and transported downhill through streams and rivers , where the heavy gold is deposited and concentrated in soaps in quiet zones of the water as a secondary deposit. Such secondary deposits can be found in sand and gravel banks , in terraces and in meandering loops of gold-bearing rivers, and more rarely on the beaches of lakes or even seas (the latter e.g. near Nome, Alaska ).

To obtain the soap of the excavator works either directly in natural waters (where it is the water depth and the reach of the excavator allowed) or a specially constructed for the excavator Stretch addition to the actual body of water. In the extreme case, the excavator hole is not much larger than the excavator itself; the material that the excavator takes away from the front is thrown out behind it, and so the excavator "eats" its way through the ground - the excavator hole moves with the excavator. The rocking back and forth and the slow forward movement of the excavator create typical, bulge-like embankments in the terrain behind the excavator ("bananas", "crocodile"), on which the excavator's trail can often be recognized many decades later if no recultivation takes place .

In regions with permafrost (Alaska / USA, Yukon / Canada, Siberia / Russia, ...) it was often necessary to thaw the frozen subsoil in advance of the excavator using steam lances before the excavator could convey the material (see picture).

Because of the remote locations and their large dimensions and weights, gold excavators are usually preassembled in a mechanical engineering factory, transported in assemblies as heavy-duty transport to the location and assembled there.

Performance data

The largest gold dredger currently in operation in the world, the Kanieri in New Zealand , reaches a length of 170 meters with booms and can dig up to 30 meters deep. Without the boom, the excavator has dimensions of 80 × 36 × 30 meters. The total weight is 3500 tons. A single bucket holds 560 liters of material and the excavator can convey up to 850 cubic meters per hour.

The former largest gold dredger in the western world, initially operated by Austral Malay Tin Ltd. on the Clutha River in New Zealand from 1938, with a length of 176 meters was similar in size to the Kanieri , but significantly heavier. He had two weaners. In 1952 the excavator was moved to Malaysia for the extraction of tin. Nearby, at Batu Gajah in the state of Perak , a similarly large tin excavator (size 75 m × 35 m; weight 4,500 tons) from the same era can be viewed as a museum object.

The largest gold excavator ever built in the world was built in 1969 by the Russian heavy machinery factory Irkutsk ( Иркутский завод тяжёлого машиностроения ) for use in the Marakan gold field near Bodaibo . The 600D excavator had a working weight of almost 11,000 tons and a size of 236 m × 50 m (without boom). His buckets held 600 liters each and he could dig 50 meters deep.

Under the most favorable conditions, a single excavator can yield up to 800 troy ounces (25 kilograms) of gold per day, which corresponds to the typical yield of more than ten thousand gold miners with traditional washing pans . A modern large excavator in Mongolia , on the Tuul River , extracts more than 1 ton of gold per year.

history

Gold excavator on the Klondike (1913)

Abandoned excavator near Nome, Alaska (1908)

Gold dredgers were developed in New Zealand as part of the Otago gold rush . The first attempts, derived from floating dredgers such as those used for dredging fairways, canals or docks in shipping, were made as early as 1863. The first high-performance gold dredger, Dunedin, worked on the Clutha River from 1881 to 1901 . Due to its great success, the technology spread quickly, first to the New Zealand gold region on the west coast and from the 1890s to all other gold regions of the world. At the height of the spread (around 1920) hundreds of large gold dredgers were in use worldwide, around 200 in New Zealand alone, around 120 in the United States (60 of them in California , 42 in Alaska , others in Colorado, Montana, ...), but also in Canada (around 25 in the Yukon Territory ), Australia, Russia (e.g. Ural region, near Kachkanar , Siberia, ...), on Papua New Guinea (Bulolo, Morobe Province ) and in various other countries in South America, Asia and Africa .

In Germany, as part of the self-sufficiency efforts of the Nazi regime from 1939 to 1943, an attempt was made to extract gold from the Rhine with the Rheingold excavator . However, the success was moderate: in the four years of its operation, the excavator only produced around 300 grams of gold. Allegedly about 30 grams of this were used to make a Nibelung ring for Hermann Göring . The ring - if it ever existed - is lost. The former work place of the excavator near Rastatt is known today as the gold canal .

In some countries of the world, in South America (Peru, Brazil, Guyana, Colombia, ...), Asia (Russia, China, Mongolia, Papua New Guinea, ...) and Africa (Sierra Leone, ...), traditional gold dredgers of various sizes are still used today in action.

Preserved historical specimens

Often gold diggers were simply left behind at their last location - usually in a remote valley far from the nearest settlement - and left to decay when their operation became uneconomical. The majority of the excavators have thus rotted away over time and possibly preserved as ruins.

A few excavators were conserved due to favorable climatic or local conditions and have been preserved to this day in partly good condition, often protected as industrial monuments and / or viewed as tourist attractions.

The following list contains - without claiming to be exhaustive - some well-known gold dredgers:

Country	region	Surname	Location	description	image
Australia	Victoria	Eldorado Dredge (Cock's Dredge)	approx. 20 km east of Wangaratta near Eldorado in Reedy Creek ( 36 ° 18 ′ 50.1 ″  S , 146 ° 30 ′ 11.4 ″  E )	Operated from 1936 to 1954 by the Cocks El Dorado Gold Dredging Company ; Total yield 70,664  oz. Gold and 1,383 tons of tin. Today museum.
Canada	Yukon	Dawson Dredge (Dredge No. 4)	in Bonanza Creek near Dawson City ( 63 ° 56 ′ 37 ″  N , 139 ° 20 ′ 8.2 ″  W )	Today National Historic Site (see listing )
		Beets dredge	in Eureka Creek near Dawson	The only working gold dredger in North America, seen regularly in the TV series Gold Rush in Alaska
Malaysia	Perak	Tanjung Tualang Dredge No. 5	south of Batu Gajah ( 4 ° 23 ′ 48.9 ″  N , 101 ° 3 ′ 11.5 ″  E )	Former gold dredger, operated in New Zealand from 1938, moved to Malaysia around 1960 to extract tin, operated there until 1982. Visible today.
New Zealand	West Coast region	Ngahere Dredge ("Kanieri")	in the Gray River Valley between Ngahere and Blackball ( 42 ° 23 ′ 12.2 ″  S , 171 ° 26 ′ 7.4 ″  E )	Built in 1937 by Kaniere Gold Dredging Company Ltd , in operation near Hokitika from 1938 to 1953, in operation again on the Gray River from 1989. Still in operation today.
			south of Reefton in Carton Creek
United States	Alaska	Coal Creek Dredge	in the Yukon-Charley Rivers National Preserve in Coal Creek ( 65 ° 19 ′ 57.4 ″  N , 143 ° 6 ′ 26 ″  W )	Today part of a Registered Historic Place (see list )
		Mosquito Fork Dredge (Lost Chicken Dredge, Cowden Dredge)	east of Chicken in Lost Chicken Creek, near the mouth of the Mosquito Fork River ( 64 ° 3 ′ 53.3 ″  N , 141 ° 47 ′ 0.4 ″  W )	Operated by the Alaska Gold Dredging Corporation and the Northern Commercial Company for only two years from 1936 . Today ruin.
		Pedro Dredge (Dredge No. 4)	in the Southeast Fairbanks Census Area near Chicken in Chicken Gold Camp ( 64 ° 4 ′ 24 ″  N , 141 ° 56 ′ 15 ″  W )	Operated by Fairbanks Exploration Company (FE Co.) in Pedro Creek north of Fairbanks from 1938 to 1958 . Moved to Chicken Gold Camp in 1998 as part of the museum . Registered Historic Place since 2006 (see list )
		Swanberg dredge	east of Nome ( 64 ° 29 ′ 33.4 ″  N , 165 ° 21 ′ 57.3 ″  W )	Today Registered Historic Place (see list )
		Jack Wade Dredge (Dredge No. 1)	in Wade Creek near Jack Wade , Southeast Fairbanks Census Area ( 64 ° 8 ′ 3.5 ″  N , 141 ° 30 ′ 42.8 ″  W )	In operation from 1907, first in Butte Creek, later in Walker Fork. Bought in 1935 by the North American Mining Company , in operation in Wade Creek until 1942. The ruin was closed in 2003 due to disrepair, later dismantled and brought to Chicken, where parts are to be exhibited
		Fairbanks Exploration Company Dredges: Fairbanks Creek Dredge (No. 2) Chatanika Dredge (No. 3) Dome Creek Dredge (No. 5) Goldstream Dredge (No. 8) Cripple Creek Dredge (No. 10)	in the Fairbanks District in the Fairbanks North Star Borough : No. 2: in Fairbanks Creek ( 65 ° 2 ′ 34.7 ″  N , 147 ° 5 ′ 36.2 ″  W ) No. 3: near Chatanika ( 65 ° 6 ′ 50.5 ″  N , 147 ° 30 ′ 23.3 ″  W ) No. 5: in Upper Dome Creek north of Fox ( 65 ° 1 ′ 46.6 ″  N , 147 ° 34 ′ 34.6 ″  W ) No. 8: in Goldstream Creek southwest of Fox ( 64 ° 56 ′ 13.7 ″  N , 147 ° 39 ′ 27.2 ″  W ) No. 10: in Cripple Creek south of Ester ( 64 ° 50 ′ 19.1 ″  N , 147 ° 59 ′ 8.1 ″  W )	Several excavators on the National Register of Historic Places today (see list )	Dredge No. 8th
	Idaho	Yankee Fork Dredge	near Custer , Custer County ( 44 ° 22 ′ 39.3 ″  N , 114 ° 43 ′ 21.6 ″  W )	Registered Historic Place since 1976 as part of a museum park
	California	Yuba Dredges No. 17th No. 21st	east of Marysville , Yuba County in the Yuba River No. 17: No. 21: 39 ° 10 '34.4 "  N , 121 ° 27' 30.9"  W.	No. 17: 1917 to 1967, restarted in 2008 No. 21: 1916 to 1988, declined in 2003.
		Tuolumne Dredge	near La Grange , Stanislaus County ( 37 ° 38 ′ 0.2 ″  N , 120 ° 28 ′ 37.2 ″  W )	In operation from 1938 to 1952. Today in ruins, protected as a Registered Historic Place
	Montana	Alder Gulch Dredge	in Alder Gulch, near Virginia City , Madison County ( 45 ° 18 ′ 18.7 ″  N , 111 ° 57 ′ 56.4 ″  W )	One of five excavators that were operated here between 1899 and 1920
	Oregon	Sumpter Valley Dredge	near Sumpter , Baker County ( 44 ° 44 ′ 33 "  N , 118 ° 12 ′ 14.8"  W )	Today part of a museum park and Registered Historic Place (see list )

literature

• Clark C. Spence: The northern gold fleet: twentieth-century gold dredging in Alaska . University of Illinois Press, 1996, ISBN 0-252-02218-1 .

Web links

Commons : Gold Digger  - Collection of Images, Videos and Audio Files

• Murray Lundberg: Gold Dredges in the North. ExploreNorth, accessed March 30, 2012 . 
• Photos on Flickr
• Photos on flickriver

Individual evidence

1. ↑ ^{a b c d e} Robin Grayson: Bucket-line gold dredges - a review of world techniques . In: World Placer Journal . No. 1/2008 . Ulaanbaatar 2008 ( full text as PDF on mine.mn ). Full text as PDF at www.mine.mn ( memento of the original from November 6, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
2. ↑ Sierra Rutile Mine. (No longer available online.) Archived from the original on April 15, 2012 ; Retrieved April 25, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
3. ↑ ^{a b} see also article Sumpter Valley Gold Dredge in the English language Wikipedia
4. ↑ Perseverance Dredge, Clutha River, working with current wheel. Photo from 1899. Auckland Libraries, accessed April 25, 2012 . 
5. ↑ Functional diagram . (No longer available online.) Hz-news.de, formerly in the original ; accessed on April 25, 2012 (lettering, in English).  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.    
6. ↑ ^{a b} Horst Zanus: Dawson City: So the gold miners were at work. (No longer available online.) Www.hz-news.de, formerly in the original ; Retrieved March 29, 2012 .  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.    
7. ↑ ^{a b c} North Klondike Highway - Km 703.8 - Tailing Piles. (No longer available online.) Sights and Sites - Yukon Points of Interest Signage, archived from the original on April 3, 2012 ; Retrieved April 4, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
8. ↑ ^{a b} Attractions around Ikamatua. Ikamatua, accessed April 4, 2012 . 
9. ↑ ^{a b c d} Hugh de Lacy: Gold by the bucket . In: Q&M . Volume 6, 5 (October / November), 2009 ( full text online ). Full text online ( Memento of the original from January 14, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
10. ^ Development of Gold Dredges. Engineering Heritage New Zealand. IPENZ - Engineers New Zealand, accessed on April 25, 2012 (English). 
11. ^ Dredging up the past. allMalaysia, December 29, 2008, accessed April 25, 2012 . 
12. ↑ ^{a b} Плавучие горно-обогатительные сооружения - ДРАГИ. (= Плавучие горно-обогатительные сооружения - ДРАГИ фотогалерея - Floating mining and processing facilities - DRAGA ( Memento of 29 June 2010 at the Internet Archive ) ). www.techstory.ru, accessed April 27, 2012 (Russian). 
13. ↑ Крупнейшая в мире драга с черпаками емкостью 600 л ... Крупнейшая в мире драга с черпаками емкостью 600 л и глубиной черпания до 50 м. Пущена в эксплуатацию на россыпи р.Маракан в 1969 г - The world's largest excavator with a capacity of 600 liters… Zoloto, accessed on April 27, 2012 (Russian). 
14. ↑ ^{a b} Gerrit Bazuin et al .: Review of the Gold Dredges in Mongolia, with comments on environmental impacts . In: World Placer Journal . No. 01/2000 , 2000, pp. 90-106 ( full text online ). Full text online ( memento of the original dated December 30, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
15. ^ ^{A b} History of Thames & New Zealand gold fields. Goldmine Experience, Thames, New Zealand, accessed April 4, 2012 .  
16. ↑ Lowburn Gold Dredging. Lowburn by the Clutha, accessed April 27, 2012 . 
17. ^ ET Spidy: Alluvial Gold. A description of the world's most modern gold dredging methods, and the construction of these monster machines in New Zealand . In: The New Zealand Railways Magazine . Volume 13, No. April 1 , 1938 ( full text online at nzetc.org).
18. ^ ^{A b} Kenneth N. Owens: Riches for all: the California Gold Rush and the world . University of Nebraska Press, 2002, ISBN 0-8032-3570-4 ( limited preview in Google Book Search).
19. ↑ ^{a b c d} Gold Dredges of the Yukon and Alaska. Retrieved March 30, 2012 .  
20. ↑ “Dredging in the Russian Empire”, The Engineering and Mining Journal, November 14, 1914 ( excerpt online )
21. ^ Rheingold extraction 2. (No longer available online.) Archived from the original on January 12, 2012 ; Retrieved April 27, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
22. ^ Rheingold 3rd Rheingold Gallery, accessed on April 27, 2012 . 
23. ↑ Harald Elsner: Gold Extraction in Germany - History and Potential (=  Commodity Top News . Volume 30 ). Federal Institute for Geosciences and Natural Resources, Hanover 2009 ( full text as PDF ).
24. ^ Peru Takes Action Against Illegal Gold Miners, Upsetting Natives. (No longer available online.) Indian Country, March 3, 2011, archived from the original on May 24, 2012 ; Retrieved April 27, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
25. ↑ Guyana's exports to Canada enjoyed mixed blessings in last five years. Stabroek News, October 31, 2008, accessed April 27, 2012 . 
26. ^ Sierra Leone: Large Mineral Sands Mining Operation - New Dredge. Retrieved April 27, 2012 . 
27. ↑ Gold Dredges, Bacon n 'Beans, Crocodiles and Bananas. Alaska Gold Forum, accessed April 27, 2012 . 
28. ↑ ^{a b} El Dorado Gold and Gold Dredge. Albury Local Internet, accessed April 4, 2012 . 
29. ↑ Parks Victoria Information Center (Ed.): Eldorado Dredge Visitor Guide . Wangaratta 2007 ( online as PDF ).
30. ↑ Historic Gold Dredge. (No longer available online.) Wangaratta Visitor Information Center, archived from the original on March 25, 2012 ; Retrieved April 4, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
31. ^ Gold Mining in New Zealand. (No longer available online.) MBendi Information Services, archived from the original on April 28, 2016 ; Retrieved April 4, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
32. ^ Biological Sciences - Photo Gallery. (No longer available online.) University of Canterbury, Christchurch, New Zealand, archived from the original on December 30, 2010 ; Retrieved April 4, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
33. ^ Jon Harding, Ian Boothroyd: Impacts of mining . In: Freshwaters of New Zealand . 2004, ISBN 0-476-00708-9 ( full text as PDF ).
34. ↑ see article : Coal Creek Historic Mining District in the English language Wikipedia
35. ^ Coal Creek Dredge. National Park Service - US Department of the Interior. Retrieved April 18, 2012 . 
36. ↑ ^{a b c d} Murray Lundberg: The Cowden Gold Dredge. ExploreNorth, accessed April 16, 2012 . 
37. ↑ The "Pedro Dredge". (No longer available online.) Chicken Gold Camp, archived from the original on May 8, 2012 ; Retrieved March 29, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.   
38. ↑ see en: FE Company Dredge No. 4 in the English language Wikipedia
39. ^ ^{A b} Parts of Jack Wade Dredge Moving to Chicken. (No longer available online.) US DEPARTMENT OF THE INTERIOR, BUREAU OF LAND MANAGEMENT, Eastern Interior Field Office, Jan. 29, 2010, archived from the original on September 10, 2012 ; Retrieved April 19, 2012 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
40. ↑ see article : Goldstream Dredge No. 8 in the English language Wikipedia
41. ↑ Chatanika Gold Dredge. (No longer available online.) Formerly in the original ; Retrieved April 20, 2012 .  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.    
42. ↑ Welcome to the Yankee Fork Gold Dredge. Yankee Fork Gold Dredge Association. Retrieved April 20, 2012 . 
43. ↑ Tuolumne Gold Dredge. The Historical Marker Database, accessed April 20, 2012 . 
44. ↑ Mike & Joyce Hendrix: Gold Dredges of Alder Gulch: Navada City & Virginia City. July 31, 2007, accessed April 18, 2012 .