Gold Prospecting Forums - General => Machine Assisted Placer Operations => Topic started by: Oro on February 10, 2018, 06:46:47 AM

Title: Gold recovery methods on top of bedrock
Post by: Oro on February 10, 2018, 06:46:47 AM
When the excavator cannot scrape or dig into harder bedrock, what are other practical methods to recover the gold laying on top of and wedged into the bedrock?  I suppose by suction using a gravel pump but have not actually seen this in use.  Venturi suction like what is used on a typical suction dredge won’t work in a deep hole.  A gravel pump however will transport the slurry vertically and out a distance to a wash plant. They make gravel pumps as small as 4”, popular in Brazil.  Gold miners in South America use 8” 10” 12” gravel pumps as a primary feed method to a rustic sluice, mostly for head ore that makes a sandy / clay slurry, pumping from excavated pits.  It’s impressive actually, very practical and definitely a cheap way to move ore to a recovery plant!  In some cases the ground water supply from natural filtration maintains a certain water level in the pit along with some makeup water from another source. They also use high pressure pumps to hydraulic excavate and move material in the pit.   

Does anyone have experience with gravel pumps?  

Here’s some youtube links of the South Americans - note they are not concerned much with environmental impact!

Bombas, dragas y equipo minero en Colombia

Dragas en Colombia dredge pump WWW.GRACOMAQ.NET

Bomba draga Dredge pump gold mining WWW.GRACOMAQ.NET

Extracción de Oro Madre de Dios

dragas putumayo 2

como sacar oro con elevadora artesanal parte #1
Title: Re: Gold recovery methods on top of bedrock
Post by: MrDave on February 25, 2018, 07:47:28 AM
My only experience with these types of pumps is decades old. We had to cross a creek in Central Alberta in the 90's, and the boss decided to open cut it.  Big mistake, it was a month of hell. We ended up using this type of pump , and it was amazing. The sand and small stones just blasted through. It took a fair flow of water to work, but they kept up with the quicksand we were dealing with.