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Friday, December 29 2017
Given a choice, most miners prefer using water to wash and run material, but in some dry, remote areas that is just not feasible. If you focus on the natural conditions that exist in desert regions and work with them, you can maximize fine gold recovery. The number one rule is that the drier the soil, the better. Damp soil conditions are very much a hindrance for drywashers. Beyond that, learning the different soil types you may encounter in the desert and how to deal with them can increase your gold recovery.
Clay is generally known as a great gold robber, making clay-bound gravels the biggest difficulty to overcome. In most of the placers directly derived from weathering lode deposits, the placers are in ravines, gullies and hillsides with sometimes very little gravels and mostly decomposed fragment of rock and fine silt from the decomposing host rock. Host rock containing a lot of feldspars are most problematic. As feldspar breaks down, it creates some difficult clays and silts that bind fine gold to small rocks and sand with the clay and silt particles forming larger clods.
Loamy or sandy conditions are much easier to process with a drywasher than clay-bound material due to the absence of clods and clumps. But if dirt clods are giving you grief, break them down with a large hammer on a canvas tarp, or use a mortar and pestle (dolly pot).
Once you are set up to run material, process in short runs before cleaning out the riffle tray (perhaps after every three 5-gallon buckets). Frequent clean ups minimize the amount of fine gold that may creep or walk down the riffle tray with the tailings. This method uses your dry washer as a form of a classifier to screen off larger material while getting rid of much of the fine silt and lighter weight material.
Re-running tailings can aid in the recovery of lost gold— especially small gold dust and flakes. The second pass through is usually much quicker than the first time because the material has already been classified. With some placers, especially flat, fine gold, rerunning material can be very lucrative. In places where gold is more coarse and angular, very little gold will like be recovered by running the tailings a second time.
You may want to experiment with adding a second layer of cloth to a portion of the riffle tray. Doing so reduces airflow by almost half in that section. In addition to the riffle tray, the void under the riffle tray can collect a sizable amount of really fine gold mixed in with fine silt.
No doubt there are going to be losses of gold when using a drywasher to recover fine gold (20 minus mesh down into the 200 minus gold), but the end goal should be to limit those losses as much as possible and these tips should help. Good luck! Learn more about Gold Buddy drywashers here.
Nugget of News Blog
Saturday, July 02 2016
Although there are many variables that go into catching gold in a sluice, perhaps properly “tuning” your sluice is the most critical. A few months ago, Steven “Doc” Vetter, owner of Gold Hog brand mats, wrote an interesting article for Gold Prospector Magazine that focused on a few key factors that all miners should pay attention to. The following ideas from his article are all about achieving the proper tuning exchange, meaning letting the junk flow out, or be worked out by exchange zones, and holding the stuff you do want—gold. A well-tuned sluice will have heavy gold concentrations up top, medium gold in the middle, and trace gold near the end, and maybe a teeny tiny bit in the tailings. Here’s why:
Hydraulic Equivalence: By definition, “hydraulically equivalent” (HE) refers to particles of varying size, shape and density that fall out of a water flow and deposit in the same area. While quartz rock and gold vary greatly in specific density, you can make them collect in the same place by making the quartz rock bigger and rounder. A 2 inch quartz rock and a 1 mm sphere of gold will fall through water and deposit in about the same place— making them hydraulically equivalent (HE). An opposite example is a .25 inch round piece of gold and a .25 inch round piece of quartz. The gold will sink through the water and likely land straight down. The quartz rock, however, will not fall as fast and will be pushed several feet away before it settles. These two items are not HE.
The shape of the gold has a big influence on its HE. Flat things move more easily than spheres when either moving water or air is introduced. HE is a huge factor in gold mining and is often the main reason for classifying material to a certain size— the theory being if everything is about the same size, the heaviest material will stay in the sluice. When you slow down a sluice, you start to have a traffic jam. Things that are HE all want to gather in the same deposit zone and you start to gather/open the window for more non-gold particles to pile up and that’s not good.
Incremental Processing: A great analogy of how this principle works is to picture a city bus. Imagine a rule where all passengers must enter through the front and must exit through the back. As they enter, passengers must fill the seats in the front of the bus first. Every time the bus makes a stop (you shoveling dirt into the hopper of your highbanker or sluice), the first few rows fill up quickly and remain full for a short period of time. As a new passenger (each new shovel full of material) gets on and finds the front seats taken, he must move further down the bus (sluice). The result is a bunch of folks all competing for the same seats up front and when there are no seats up front, they must take the next available one. If all the seats get full, a passenger (your paydirt) never even gets to sit down and exits the bus (sluice) without ever sitting (collecting in the riffles). As the working zones in your sluice fill up, slurry material will move down to the next zone before it settles there. During times of heavy loading, the first percentage of your sluice will load up heavy and take some time to exchange out. That means gold will keep traveling until it finds an “empty seat.”
If you load too heavy or have too short of a sluice, you’ll have gold flowing over holding zones that are busy working and exchanging. It may take an exchange center (vortex) 3 or 5 seconds to fully process down material and exchange out non-gold and heavies.
Fine Tuning: Because of the principles of Hydraulic Equivalence and Incremental Processing, you may have realized that slowing down a sluice can really cause problems and loss of gold. How do you know if your sluice is running too fast or too slow? Experiment! Of course doing so is a little scary because the #1 fear of most gold miners is losing gold, and quite honestly, until your sluice is fine tuned, that just might happen. To avoid losing gold, most miners start running their sluice at the “normal” or widely accepted pitch of 1 inch per foot. But this is just a starting point. If you see gold in your tailings, your first thought is probably to slow it down so you aren’t blowing gold out of the sluice. But perhaps that’s not the cause at all. Perhaps it’s because gold doesn’t have a place to sink down into and hide in your sluice. Experiment by running way too fast, say at a 15-degree pitch. Then take it to 13 degrees, then go down to 12.5. Keep adjusting until you find an acceptable capture rate for the size of gold you want to hold.
Lose your fear of losing gold through testing and experimentation. Not only will you fine tune your sluice, but you’ll also get a great education. Good luck!
Monday, March 04 2013
Once primarily used by landscapers and construction contractors, gold miners are now using Rock Crushers / Pulverizers to save time and get more gold. In most cases, you can take your rock crusher straight from the shipping container and use it in less than half an hour. No wasted time trying to find the right pulleys or chains because you get everything you need when you place an order. A rock crusher that has been designed and built by miners for miners can be an invaluable tool -- these tough machines are built well and rigorously tested in the field.
Whether you need a manual rock crusher or a power rock crusher (choose gas or electric), turn rock into talcum powder and get ALL the gold!
Nugget of News Blog