Small Mining

Surf Washer for Beach Deposits

Few sea-beach-type placer gold deposits have been mined successfully. The most important producers have been in the vicinity of Nome, Alaska, but gold is also known to occur in a few other shoreline bordering the Pacific Ocean. Special techniques have been developed to utilize the action of the surf in recovering gold from these deposits.

Surf washers are similar to long toms, but wider and shorter. They can be used only when the surf is of proper height. They are set so the incoming surf rushes up the sluice, washes material from the screen box or hopper, and retreating, carries it over the riffles and plates. One man can attend to two surf washers, and about 8 cubic yards can be handled per 10 hours.

An example of a simple surf washer is a riffled sluice 3 to 4 feet wide and 8 to 10 feet long, set on the sand at the water's edge so that the incoming waves wash through it to the upper end, and retreat below the lower end. The sluice is made of boards nailed to sills at either end which can be weighed down with rocks or otherwise. The sides are 4 or 5 inches high. The riffles in the example are made in sections of about 1- by 1-inch strips spaced about 1 inch apart. The end sections are transverse riffles, the center section longitudinal. The box preferably is set on a grade of 8 to 10 inches per 12 feet. Best results are obtained by using carpet under the riffles. When the surf is strong, the washer treats as much as two men can shovel, but at other times it has to be fed very slowly.

[ Small Mining - Rocker Dip box Long tom Sluice Surf washer Dreging Dry washer ]

From: Bureau of Mines Information Circular 8517 by J.M. West, released in 1971.