Selection of an appropriate dredging system and the subsequent determination of dredging equipment are two the most important decisions confronting a project engineering staff during the initial study of a new gold placer deposit. Probably, the selected dredging units average from 60 to 70% of the total capital outlay for mine equipment and their selection affects the type, size and quantity of attendant equipment such as loading shovels and bulldozers. The metallurgist is obliged to analyze the all possible options, even some techniques similar to dredging lines. For example, the employment of a simple bucket wheel excavator must be analyzed. Its ability to dig the top lying material is accepted, but the final decision must be done considering the lower strata of sandstone. Also hard, unforeseen and obscure inclusions such as boulders or lenses of hard material could spell disaster to a wheel excavator operation.
The disposal of the spoil frequently becomes a problem though it could possibly be accomplished by an overcast machine or a stacker operated in conjunction with the dredging device; or the U system may have been necessary. The net result could be a more complicated disposal system, consequently more costly. The possibility of employing several large stripping shovels must be closely examined. In this way, several major factors, including reduced flexibility of operation, have an impact on the final selection.
Suction Dredge