Suction dredges are still one of the best ways to recover large amounts of gold from a placer mining operation. They suck up gravel from a riverbed and process it through a floating sluice box. If you find a rich paystreak, they can recover a good amount of gold during a day of dredging.
Dredges come in many different sizes and each can work for you depending on your needs. From small backpack sizes to large dredges that are run by a crew, they can each work well in various situations.
Small dredges generally have suction hoses in the 2 to 2.5 diameter. Many of these are set up so you can pack them on your back and access areas that are difficult to reach with other dredges.
Small suction dredges like these are best for working shallow water along rivers or in small creeks with shallow, exposed bedrock. You can pack these into backcountry creeks that perhaps have never been mined before with modern equipment.
Backpack dredges can work well in the right situation, but their small size limits the amount of gravel that can be processed in a day of mining.
Some dredges made today can be adjusted and used as highbankers as well as suction dredges. These are pretty popular, and seem to be a necessity today for some areas where dredging opportunities are being limited by regulation.
4-6 One-Man Dredges
Most miners who dredge use a dredges with hoses from 4 to 6 in diameter. These are the most popular sizes for a variety of reasons. For one thing, these dredges are still manageable to use by one miner, although its still a good idea to dredging in pairs for safety. It can also be helpful to have a second miner to move rocks.
These dredges are larger and more expensive. Some miners have designed their own with some success. You can also find dredges of this size that are used with some regularity for reasonable prices.
The larger hoses can be tougher to handle, but a 4 diameter hose is still quite manageable and you can process a good amount of gold-bearing material in a day.
With bigger dredges like these, most miners use a hookah diving system to access deeper areas in river channels where gold may be hiding.
Large Commercial Crew Dredges
There are dredges that are much larger and are often used in commercial placer mining operations. These will have intake hoses that are 8, 10 and even larger in diameter. Once they are tuned and setup properly they will really move a lot of material!
Bigger is often better, but there are many downsides to these bigger dredges. They are very expensive. They can be unruly to handle underwater and are too big for most people to use for an entire day of mining without wearing out physically.
In the U.S. there are generally regulations that limit the size of dredge that can be used, but in many countries around the world there are some very large dredging operations. They operate on large rivers and even in the ocean. You have probably heard of the mining at the beaches of Nome, Alaska. Huge commercial dredges are still used to vacuum up gold from the bottom of the ocean floor.
Also Read:Fine Gold Recovery
And: Finding Gold After a Storm
Picking a Dredge for You
The proper dredge will depend on your needs. For most gold prospectors in the U.S., a standard 4 suction dredge is the perfect size. It is small enough that it can be used in most rivers and large enough that a good amount of gravel can be processed.
Smaller backpack dredges can also work well for some prospectors, but the small size will limit gold production and work best in small gold-bearing creeks with lots of exposed bedrock.