Analysis of low reachability of gold dredger's design capacity;

The current technological situation of combined mining with bulldozer and gold dredger and approaches to its perfection;

Discussion on application of silicon controlled rectifier in gold dredge;

The checking computation of structural size of gold dredge in mining of gold placer;

Ways of raising recovery rate of oredressing by gold dredge;

The calculation of the space between the excavator bucket and feed launder of dredger;

Wear resistant cast iron is used to replace the more expensive silzin as the lower cylinder bush of a dredger because of its low cost，good wear resistance and shock absorption.

Based on the theoretical and practical analysis on three - stage dredger jiggingand the comparison with other flowsheets, it is considered that the three -stage jigging flow-sheet is most advanced in the common used flowsheets although there are rnany short-ages.

On the basis of the analysis of factors influencing the mining operation of bucket-ladder gold dredger, this paper made an inquistion into the feasibility and mining characteristics of a sort of multi-function and deep excavation gold dredger, ie, hydraulic bucket grab type of gold dredge