Dredging Your Way to Prospecting Success

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Dredging Your Way to Prospecting Success

Dredging Your Way to Prospecting Success

Understand Dredging Basics

If you’re out to mine some buried treasure, you need to learn about the concept of dredging. It’s considered perhaps the most effective method of small scale prospecting, and it’s gaining in popularity.

Simply put, dredging involves using a suction dredge to vacuum gravel from the bottom of a creek bed. Usually, a dredge is a sluice box affixed to a four-legged stand or positioned on floats. An engine pump is then either mounted on the floats with the sluice box or positioned on shore. High pressure water flows from the pump through a hose to a jet tube or power jet nozzle. Using the simple principle of suction, you are able to bring in gravel, rocks, and gold.

Determine Your Dredge Size

Dredges are not one-size-fits-all; there are a variety of sizes from which to choose. You can select anything from a one-and-a-half-inch backpack dredge that can be easily moved to a remote location, or a version as large as 12 inches. The size of the dredge is determined by the diameter of the suction hose, not the nozzle.

Typically, the suction nozzle is fashioned from steel and is generally the diameter of the suction hose. The opening of the nozzle is ratcheted down with a restriction ring so that the opening is decreased by about one-half inch. This means there is less chance that a rock will plug the hose up. To give you some idea of the size of dredges, a three-inch hose size with a nozzle opening of two-and-a-half inches can be used in an area with a maximum dredge size restriction of two-and-a-half inches.

Design Choices for Dredging

As with other small scale prospecting equipment, dredges tend to vary in design. Gravel enters the sluice box either by means of a “Header Box, which slows the passage of water, or by a “Jet Flare”, a long flaring tube which accomplishes the same feat. For many years, the Header Box has been the mechanism of choice, but the Jet Flare dredge is gaining in popularity because it offers more suction at the nozzle.

In some cases, with smaller dredges, inner tubes will be used as floats. Most larger dredges utilize plastic pontoons, which can be collapsed for transport. For shallow water, dredges that are high banker-dredge combinations are used. These have a four-legged frame which holds the sluice box. Larger dredges (three inches or greater) may have a breathing air pump positioned on the engine-pump to carry compressed air to the dredger, who can then go underwater to obtain gravel that might not be otherwise accessible. This feature is significant because the bottom of a riverbed may be characterized by cracks in the bedrock that have gold trapped inside.

Dredges, High Bankers, and the Gold Lab: Efficiency in Action

Many prospectors consider dredges to be an efficient piece of machinery, tailor-made to suit your needs. For beginners, experts recommend a two-and-a-half to three-inch dredge high banker combination. This rig is versatile and efficient, and can be counted on to unearth a great deal of gold. But if you are already a seasoned prospector, experts suggest obtaining the largest dredge you can afford.

After the dredging work is done, the Gold Lab becomes your next best friend. The Gold Lab allows you to get the fine gold that panning won’t, and will allow the ability to process more concentrates for their fine gold. It all boils down to economics:  fine gold is just as valuable as a nugget, it just takes more of it to be worth the effort. In one sense, there’s a lot more fine gold available than there are nuggets. So, if you don’t want to spend all your time panning, the Gold Lab will eliminate that part and speed your recovery process up, considerably.

Know Local Regulations!

Most importantly, recognize the fact that you will have to operate under specific laws, regardless of where you are in the world. Regardless of the equipment you are using, understand and adhere to your local laws to ensure that you enjoy safe, successful, and legal prospecting.

 

The Gold Lab
About The Author
I’m Dave Chiara, and it was only a few years ago that I picked up a gold pan and couldn’t put it down. I happily spent my weekends dredging, processing, panning, and sluicing. I can’t imagine a better way to spend your free time – out in nature with friends and family, and coming home with real gold!

2 Comments:


  • By Jason 04 Oct 2016

    Hi there I am new to all of this but would like to build a gold dredge with a 2 or 2.5 inch suction hose and use vortex dream mat on it up the top about 1M long by 24 inch wide and carpet and riffles below about the same length. I live in Queensland Australia and the Gold I find is very fine powder like in both clay and sandy gravels. Do you have any suggestions on what pump I need such as flow rate and head flow and would this type of set up would work. Any help would be great as I cant find anyone in my area with any knowledge.

    • By Dave Chiara 04 Oct 2016

      Hi Jason – your question should be directed at a dredge builder or supplier – but since they manufacture and sell the equipment, they really don’t want to help you build one on your own. The Gold Lab and Thumper process concentrates once they are collected via a dredge, highbanker or sluice, so I am glad to help where I can.

      You don’t say whether you’re a member of a local prospecting organization in Queensland or not – but if you’re not – you may want to attend a few meetings (or join) and get hands on help from those who have been doing this sort of thing for some time.

      I looked up the Vortex Dream Mat and found several YouTube videos showing it’s operation. Interesting. I don’t have any real experience with this mat although I am familiar with it’s principles, etc (I have a Gold Well that’s an aluminum version of this mat) so I can’t really offer an opinion either way on processing your materials (not having seen them or run them). I personally prefer the Gold Hog mats but realize not everyone wants to pay that kind of money for them either. Regardless of how you capture your concentrates, if you have fine gold in your concentrates, then reducing the flow rate thru your sluice will generally help capture more fines.

      Now, the big question is – are you looking for fine gold only or do you have any nugget sized materials? If all you have is very fine gold then slower pump speeds and volume is essential to keep the fines in your sluice. I don’t really think it’s a important what type of pump you use, but more importantly how you use it. Any reasonable good commercial motor and pump should do the job. I would suggest if you have some buddies with different types of motors and pumps – test their run off (materials that have been cast off the end of the sluice to see how effective their systems are – ie if you pan some samples and find small gold being blown off – they’re running too much volume and/or too fast). If their system does pick up the fine gold – and after testing it seems to represent what’s representative in the materials they’re processing – that’s probably a good system to try and replicate. That’s where going to a local prospecting chapter would be helpful (and attend some outings to learn the best techniques and what equipment they’re using).

      I know I didn’t answer your question directly, but I think if you seek out others in your area and see what they’re using – you’ll save time and money plus pick up a lot more tips than just by trial and error on your part.

      Best Regards
      Dave
      The Gold Lab

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