The gold would settle in the sluice boxes for collection.Holes in the screen would allow the gold and fines to pass through to a sluice box Water was sprayed through the trommel, washing off the gravel.The trommel was a revolving tube-like metal screen, constantly rotating.The bucket line on the bow dug up gold-bearing gravel and deposited it to the hopper.The original dredge operating procedure was as follows Gold Dredge Types -Working & Operating Principles Number 4 Dredge, YUKON Dredging was mostly controlled by mining companies’ not individual prospectors as they were too expensive. In 1912, in the Klondike, there were over 13 dredges working.
Over 46 years, it unearthed 9 tons of gold, grossing 8.6 million dollars for an average of $1000/day. 200 days, April – November, but weather dependent. It would operate for 24 hours per day (as do modern mines) for a season of approx. 4, and it was 2/3 the size of a football field and eight stories high! At its heyday, it would move along in a pond made by itself, and its digging rate for gold-bearing gravel was 22 buckets per minute. The largest one in North America has been preserved near Dawson City in the Yukon. The original gold dredges were mostly wooden and were quite large. After WWII, increased wages and the fixed price of gold eventually took their toll on profitability, causing dredging to cease. These original dredges were in operation up until about 1966. Prior to the advent of the dredge, placer techniques were mainly limited to gold panning, and use of rockers and sluice boxes, and later hydraulic monitors. These gold dredges typically harvested the sand and gravel from the bottom of the streams and rivers which had been inaccessible to the old-time prospectors who were limited to the river banks and peripheral sand bars. Some of these gold fields are the California ones of the Sierra Nevada 1849 gold rush, the Yukon one of the Klondike area near Dawson City and Atlin, BC. Original gold dredging began in the very early 1900’s, mainly to harvest gravels and sands for gold in previously worked placer gold fields.
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