In the section that immediately follows, specific cost data for dredge operations considered representative in the industry have been updated and listed. Following this is a section on general cost data that correlates operating costs to annual production according to bucket size. These costs cover dredge operations in the Western States. Cost of dredging in … Read more
Determining Suitable Dredge Size: After the placer deposit is properly prospected the miner has a reasonable knowledge of the volume and grade of the placer together with information on its geometry, formation, and the distribution of values by size and location as well as information on bedrock topography, surface topography, water supply, and a host of … Read more
Once aboard the dredge, the dredged material is classified, its valuable portion recovered, and its waste portion disposed in a coordinated recovery disposal system designed to handle the capacity of the digging system. Also on board are the dredging-support equipment of the spuds, winches, and controls, and the water-supply systems. The recovery equipment consists of … Read more
At present dredge mining in this country is at a low level. The last gold dredge in California stopped operating in October 1968. Gold dredging in the adjacent States had already ceased because of increasing operating costs, decreasing placer values, and the fixed price of gold. Two gold dredges and one platinum dredge were still … Read more
Let us assume that it is desired to design a hydraulic dredge capable of raising average hydraulic material 15 feet above the pump through 4000 feet of pipe line and at the same time be suitable for general all round work involving also short lines and low heads. It is generally accepted that a 20 … Read more
The most common conveyance for the transportation of dredgings (pumpings excepted) is the bottom-dump mud scow. It is in effect a hopper barge, without means of self propulsion, consisting simply of a hull rectangular in plan and cross section, containing a number of independent hoppers called pockets, and with both ends raked or rounded (in … Read more
Dikes for River Control.—Dredging and the maintenance of dredged depths is intimately related to the subject of the characteristics and regulation of rivers. This, however, is much too broad and far reaching in its scope to be included within the narrow confines of this small book, and will merely be summarized with maximum brevity in … Read more
There are two general and distinct classes of hydraulic dredges, the River Type and the Sea-going Hopper Dredge. The first is the smaller machine, built for use in the calm waters of rivers and sheltered harbors, and is rarely self-propelling except among those designed by the Mississippi River Commission to meet the special and unique … Read more
General Description.—As has been said, the Dipper Dredge “ digs ” like the familiar steam shovel. The bucket, which is essentially a scoop with heavy teeth and a flap bottom, is attached to the end of the dipper stick, which is carried by the boom at or near the centre of the latter. The boom … Read more
General Description.—A grapple dredge is, in principle, a derrick mounted on a float and swinging a grab bucket. Any derrick lighter may perform the operation of dredging by simply attaching a grab bucket to its fall. This, however, is merely a makeshift, and by no means constitutes a dredge. The operation of the bucket is … Read more