Saturday, July 12, 2008

Placer Mining Equipment: the Highbanker


Placer Mining Equipment: the Highbanker

A highbanker (also known in some mining circles as a power sluice) is a piece of placer mining equipment used for processing auriferous gravels located some distance (typically up to 100 feet away) from a stream or water source. By using a motorized pump and tubing or hose, the highbanker is able to send a large volume of water onto the unit's hopper (classifying screen) and through the sluice box to recover gold.

Highbanker pumps can be either electric (12-volt battery) or gas driven, although the gas-driven models seem to be the most prevalent out in the field. Some highbankers are also designed and constructed to re-circulate water so they can be employed in situations where there is little, or even no water at all (the miner uses jerrycans of water and a recirculation tub). Highbankers in this latter case are typically electrically driven.

Additonally, some gas-driven highbankers have the capacity to be used as a suction device, much along the lines of a small suction dredge. Obviously, the highbanker unit remains out of the water and on dry ground, but an intake hose and nozzle of 2.5"-3" diameter can be employed directly underneath the stream surface to "vacuum up" gold-bearing gravels or to clean bedrock surfaces. (I used to run a "suction" type highbanker quite frequently, so I am very familiar with them and highbankers in general.)

Highbankers are typically employed in one of two ways: 1) gold-bearing gravel is shoveled onto the hopper screen or 2) a suction nozzle is used underwater to vacuum up gold-bearing material. That's essentially it. Otherwise, the highbanker functions much in the same fashion as a regular sluice box, with a steady flow of water washing the barren and lighter materials down and away from the riffles out the lower end, while trapping the heavy black sands and gold in miner's matting or indoor/outdoor carpeting, and behind the riffles themselves.
Main Advantages of a Highbanker:
  • Can process gold-bearing gravels located some distance away from a water source (you bring the water to the gravel, not the gravel to the water)
  • Reasonable portability and ease of set up
  • Able, in most instances, to operate (for limited periods of time) using recycled water
  • Some models can "double up" for use as a suction device with small diameter intake hose and nozzle attachment
  • Additionally, some models have a "garden hose" attachment that can be used for cleaning light overburden from bedrock cracks or crevices
  • Extremely efficient gold-trapping ability, including very fine or "flour" gold
  • Easy clean up of gold-bearing concentrates
  • Overall versatility
What are the downsides to using a highbanker? Few come to mind. But they can be quite expensive ($1,200.00-$2,200, estimated) to purchase new and like anything mechanical, they can be balky at times or even break down on you. So if you don't have good mechanical skills make sure you have a back-up plan (a regular sluice box or rocker or?) out in the field. Additionally, please note that the highbanker suction hose diameter is fairly small and rock jams can be a real pain in the rear at times. Just so's you know...

I've know a number of recreational placer miners over the years who designed and constructed their own highbankers, and those home-made models did a pretty good job of getting the gold out in the field. However, building a highbanker will be much more difficult and costly than constructing a home-made sluice box or rocker. So be realistic about your "do-it-yourself" abilities before taking this task on.

(c)  Jim Rocha (J.R.)  2008

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