Ever heard of the Pyramid Rotary Jig?, Its not a jig, its better than a jig... Options

[Steppegold]

With Stickwhipper and other Alaska Gold Forum members, we would appreciate any help in tracing the whereabouts of this remarkable device - please read carefully:

This advert is all we have to go on, and it is thought that production ceased in the early 1990s. Nobody we know has got one!

Here is my doodle of what it MIGHT look like inside:


Its exciting as it is NOT a jig, as it lacks a jig screen, has no ragging, lacks a hutch, and lacks any vertical jigging motion!

Instead the Pyramid Rotary Jig is a member of a special class of gravitational devices only recently recognised and this class seems particularly good at recovering fine gold.


Here are my notes on what we think its all about...
In the early 1990s Pyramid Industries of Santa Clara, California made the Pyramid ‘Rotary Jig’. Manufacture ceased and we traced neither inventor nor company. A company advert is the sole source of data.
The device lacks jig screen, jig bed, ragging, hutch chamber or vertical jig motion. The advert stresses it differs from hutch jigs and diaphragm jigs. Rather the invention belongs to a family of gravitation devices termed ‘elutriated sludge tanks’ (E-tanks) that seem particularly suited to recovering very fine gold.
The Pyramid ‘Rotary Jig’ is here renamed the ‘Pyramid E-tank’. Model #T50 consists of a circular tank tapering from 22-inch diameter at the top to 18-inch diameter at the bottom. The taper is said to be significant.
Operation
The tank is first filled with screened material – how much screening is unclear. When the tank is full of sediment, pressurised water injected from below – how much pressure is unclear. As with other E-tanks, little water is required. Water consumption varies with the gold size to be recovered – 2mm gold requires 2,725 litres/hour for a throughput of 4 tons of solids, down to very fine gold (<100 micron) requiring 454 litres/hour for a throughput of 0.9 tons, and for the finest gold 114 litres/hour for 0.5 tons of solids.
Once the pressurized water is added, the stirrer blades are able to begin to rotate – how fast a rotation is unclear. The blades are simple metal bars welded at intervals along a central solid metal bar that acts as the drive axle turned by a 110-volt A.C. electric motor mounted above the tank. The device is innovative in slurrifying by rotary stirring. The gold and other heavy particles spiral down, while the lights spiral upward. This seems to be in thixotropic sludge-like slurry.
After several minutes of operation, the barren tailings are bled through the tank wall via drain taps at two levels. Then the tank is refilled and the process repeated “over and over again” until an “ultra-rich concentrate” is achieved. A concentration ratio as large as 2000:1 is possible and the concentrate is removed from the bottom of the tank via a concentrate tap as a batch discharge. Continuous operation is possible with automatic feeders.
Adoption by placer gold miners
The device seems to have enjoyed a brief period of moderate interest from recreational miners in North America but then swiftly vanished into obscurity. It is unclear if any such devices are still in use in spite of their clear potential for fine gold recovery.

[russau]

i dont think you could add to much material into this device before the motor is overloaded and stops. it appears tobe another device(bigger,motorized) like Megan posted a couple of years ago. from the price tag plus shipping, it looks like he has that much($45.00) in parts! yep its the next post down! just saw it!

[Steppegold]

i dont think you could add to much material into this device before the motor is overloaded and stops. it appears tobe another device(bigger,motorized) like Megan posted a couple of years ago. from the price tag plus shipping, it looks like he has that much($45.00) in parts! yep its the next post down! just saw it!

Hi Russau - I take your point. However, bearing in mind that the water is injected from below into the Pyramid Rotary Jig, and fluidised the contents reasonably well, then the resulting slurry should hopefully be fairly easy to rotate - and yes it sure would burn out a small motor! And it looks way overpriced.

As for the other device (Quick Gold Concentrator) this at first glance looks rather similar but is actually very different. For a start, it is intended for ungrading concentrates (see the patent) whereas the Pyramid Rotary Jig is for processing raw placer gravels. The next point is that the Quick Gold Concentrator needs very little energy as there is no rotation or pulsing, just water pressure from below.

Somewhere in the midst of these devices that work or nearly work, and disappeared off the radar screen, I believe there is an opportunity to develop cheap DIY devices that will recover fine gold quickly and easily. We shall see.

Steppe

[russau]

i understand that! but it is just a modifiacation to this simple proccess of fluidizing your cons and letting it drop out. cons or raw material, its the same principle! and if you load up this devive(even while being fluidized) the more material you put into this the more load will be generated to the motor. that small motor wont turn any bigger(raw material) rocks even if fluidized.

[Steppegold]

Russau - sure, right on the nail. The key perhaps is that tailings are being ejected all the time as continous discharge, and so there is more capacity to add more feed material to replace that ejected as tailings. Provided screening is fine enough, there should be no rocks plummetting to the bottom of the device.

I think it is a lot more complicated than it seems, as it is not just fluidising it is also density and size strafication coupled with washing, at the same time as allowing heavies to drop and lights to rise. Lots of scope here for complications such as hindered settling.

From what we have gleaned so far, the Pyramid Rotary Jig is certainly not a jig. Furthermore it is not a elutriation column either (e.g. ASAT E-Tower and Quick Gold Separator), and seems best to group with Graefe's eleutriated sludge tank that was the Keene Hydromatic Jig (not a jig either) and Arthur Duke's elutriated sludge tank. Unlike the E-towers, the water injection was just enough to turn essentially dry material into a thixotropic sludge that was liquid enough to be rotated as a porridge-like mass with many particles in close proximity to each other. In the E-towers the sludge is watered much more to become dirty water in which particles are much more dispersed and are able to rise or fall much faster.

Therefore it seems that the Pyramid Rotary Jig and Megan's 'Quick Gold Separator' are radically different from each other and merit putting in different classes of gold recovery devices.

At the moment the idea is just to gather information on the Pyramid Rotary Jig to see if and how it manages to balance all these interactions adequately enough to recover fine gold efficiently. Then to build it once we have more information.

Steppe