----- Original Message -----

To: nginther

Sent: Thursday, March 11, 2004 5:09 PM

Subject: RE: Heavy Metal Recovery

 

Dear Neil,

 

Thank you for the reply.

 

To simplify your review of appropriate material I have attached an applications note for our flow-though pipe-clamp technology.

 

What will be the volume of slurry you will need to treat?  Estimated nameplate slurry volume is about 95-100 cubic feet per minute.  This would equate to approximately 712 to 750 gallons per minute.

 

What is the solids content of the slurry?  The current design calls for feeding the Falcon Concentrator at 70% solids.  Weight of solids is approximately 120 pounds per cubic foot.

 

I look forward to your reply.

 

Mario Plasencia

Active Ultrasonics S.ar.l.

Puits-Godet 6A, CH-2000 Neuchatel,  Switzerland

Tel: +41 32 727 3807  Fax: +41 32 727 3809 

Email:  m.plasencia@activeultrasonics.com

Web Pages:  www.activeultrasonics.com

 

 

-----Original Message-----
From: nginther [mailto:nginther@cox.net]
Sent: Thursday, 11 March, 2004 17:00
To: m.plasencia@activeultrasonics.com
Cc: Edwin Hiserodt
Subject: Re: Heavy Metal Recovery

 

Dear Mr. Plasencia:

 

Please excuse my delay in responding -- it is not from a lack of interest, rather a lack of time on my part.

 

Thank you for your kind response.  I am looking forward to speaking with you in the near future.  It appears that we are going to start our last round of exploration data verification and landwork around the first of April.  This is the last step before beginning the final design and engineering for the pilot plant.  This work should be completed within about ninety (90) days.

 

The preliminary design for the pilot plant calls for a net average throughput rate of approximately 130 cubic yards per hour on a 24/7 basis.  The nameplate capacity will be about 240 tons per hour with an average material weight of 3220 pounds per cubic yard.  I am attaching a schematic of the current preliminary plant design which was prepared prior to our considering the potential application of ultrasonics therein.  These schematics are drawn using QuickCad which can be opened with AutoCad.

 

The material to be processed generally exhibits the following average screen size distribution:  +40 mesh -- 3.38%; +50 -40 mesh -- 5.95%; +70 -50 mesh -- 8.37%; +120 -70 mesh -- 32.08%; +200 -120 mesh -- 36.45%; +325 -200 -- 9.53; -325 mesh -- 4.23%.  The gold particles appear to be virtually all -20 mesh, with the majority being -120 mesh. To the Company's knowledge the largest single piece of gold discovered to date in several hundred test samples from these surface materials was approximately 20 mesh (0.85 mm or 0.0335 inches) on its longest side.  Some recent tests on samples taken by others and processed on a UHF Concentrator reported recovery of gold particles estimated to be in the 3000-mesh range.  Based on several hundred samples processed (mainly on a simple, drag plate and sluice recovery system) the average gold recovery without scrubbing averaged approximately 8.05 grams per cubic yard.  This system will not recovery any appreciable gold smaller than 200 mesh and likely loses a fair percentage of the gold content smaller than 150 mesh or so.

 

Preliminary testing has shown that "scrubbing" the particles greatly increases the gold recovery, sometimes as much as 100%.  Evidently some of the particles are in clusters which end up being rejected along with the gold particles contained therein.  Based on a quick scan of the material provided by MPI it would appear that ultrasonic treatment could be very effective in breaking up these clusters.  I must admit that I have not thoroughly studied the material provided but will do so within the next two-three weeks.

 

The following briefly describes the preliminary plant design and operations as envisioned at this point.  The mined material will be delivered to a 2" vibrating screen where any large rocks, vegetation and other oversize materials will be removed and placed in reclamation stocks.  The material then falls into a feed hopper from which it will be fed to an Aggregates Equipment - bivi-TEC 8’ X 24’ double deck screen equipped with 1/4" and 20 mesh screens.  The oversize material (+ 20 mesh) will be conveyed to reclamation stocks with the undersize (- 20 mesh) being fed to a slurry mixer.  The slurry mixer is designed to impart a hydraulic scrubbing action to the material to thoroughly break apart the components of the material.  The slurry mixer will blend the material to the proper solids content (about 70%), and deliver the slurry to a Falcon SB5200 centrifugal concentrator.  The tails from the concentrator will be dewatered and conveyed to the reclamation stockpile.  The concentrates carrying the heavy minerals will be fed to a finishing concentrator for final cleanup.  Concentrates will be moved off-site to a secure location for further processing to separate the gold from other heavy minerals and prepare it for refining. The remaining heavy mineral streams will be stockpiled for further processing to recover any remaining values.  There will be little concentration of free gold at the plant, thus reducing security concerns.  The tails from all plant segments will be recombined and placed back into the mined area for reclamation.  See:  Pilot Plant Flowsheet -- Figure One, and Pilot Plant Schematic -- Figure Two attached hereto.  The pilot plant will be totally enclosed within a steel building to allow 24/7 operation; and protect the water circuits from freezing.

Once the pilot plant is in operation and the process fine tuned and operating efficiently we plan to increase our processing capacity over the next four (4) years to approximately 2,600 cubic yards per hour.

I hope the above gives you a basic idea of where we are and where we intend to go.  Your comments and suggestions will be greatly appreciated.

 

Again, I look forward to speaking with you at your convenience.

 

Best regards,

 

Neil