DIVING FOR GOLD

Hokitika Guardian, 17 August 1929, Page 3

DIVING FOR GOLD

NEW DEEDGING DEVICE. How a diver in conventional rig, having in his hand the end of a hose attached to a steam puanp, manages to suck up gold from v a California stream already “worked” by early gold seekers as well as they could do it by hand, is described by Floyd M. Blanchard in “The Engineering and Mining Journal” (New York). The writer asserts that this is the first successful attempt to recover gold in this way. The earliest plant constructed was wrecked by a flood in 1927, and the present one replaces it. Says Air Blanchard: “Deposits of placer gold in the channels of mountain streams, particularly those which, cairy much water all the year round, are usually so confined in a deep narrow gorge that small possibility exists of diverting the water into another channel to make possible a clean-up oi the gold. To overcome these difficulties a pew and interesting method, a combination of a diver and a centrifugal pump, lias been devised, and is in successful operation in California.

“The dredge is being operated in the middle fork of the Feather River', near Kanaka bar. This goldb'earing bar has been worked by pioneer miners, in the early days, and in later' years by various prospectors. The gravel lias been worked as far out into the stream as it was possible for men to wade. Below the bar is a large basin, about 1000 feet in length and varying from 100 to 300 feet in width, which has served to catch a. large quantity of gold-hear-ing gravel ail'd sand. 1 “Machinery necessary foil' the dredging operation is mounted on a woodbn hull. A six-inch gravel pump is driven .by a four-cylinder gas engine. Attached to the suction of the pump is a flexible rubber hose,. hung from a short swinging stiff leg derrick on the bow of the hull. To operate the suction hose a diver using a complete diving apparatus is required. He is able to work at any point from near the surface to a depth' of 30 op 40 feet. The ice cold water necessitates the use of diver’s mittens, but otherwise .no special equipment is necessary.

“The diver, after being dressed in his heavy rubber suit, steel helmet, lead holt, steel-shod shoes and watertight mittens, climbs, down a ladder on the bow of the hull, and, grasping the end of til© rubber suction liose. moves it about ih the- crevices of the bedrock and between the loose rocks distributed over the bottom, of the river bed. In places where the gravel is covered with stones it has been found advantageous to first clear out a part of the larger rocks. This is done by means of a steel wire. The diver attaches the wine to a large ;rock, signals the engineer, to pull away, and the rock is dragged out of the way. When a great many rocks are encountered that arte just oversize for the pump, a net is used. Tire net is dragged into position near the spot which the diver desires to clean out, and, when filled by the diver, it is dragged hack out of the way and dumped. “The gravel pump discharges into a long sluice box provided with steelshod wooden trap riffles, between the bars of which quicksilver is placed to :amalgamate the gold. “Operation of the dredge is practically continuous during daytime. The diver stays down about two hours at a time, and then comes up for a short rest. Three men are needed .to operate the dredge—the diver, his assistant, who tends the signal line and air compressor, and an engineer to watch the pump and engine. While the dredge is working it is kept pointed up stream ‘by means of mooring lines, so that the discharge from the gold-saving sluice is down stream back of the diver, thereby permitting him to work always in clear water and to be able to see what he has to do. Owing to the shallow depth at which he ordinarily works no serious after effects are experienced. The cold water causes the greatest inconvenience,, hut this is overcome by the continuous activity necessitated in moving the suction hose. “Various attempts to recover placer gold and tin with a centrifugal gravel pump have been made, but none had proved successful until the abovedescribed dredge ,was built.’’