BRYSON BURKE
Home
Mission
Board
History
Business Plan
Latest Information
Building Our Drill
Innovation
Photo Album
Satellite Weather
Free News - Sign Guestbook

INVESTING
Investment
Stock Quotes

COMMUNICATION
Press Releases
Newsletter
Current Information
Contact

SITE GEOLOGY
Geology Reports
Site Geologic History
Magnetic Maps Index
Heavy Minerals Index
Grenville Province Index

DIAMOND POLITICS
Blood Diamonds
Kimberley Process

DIAMOND GEOLOGY
Indicator Minerals
Kimberlites
Decay of Kimberlites
Kimberlites & Magnetics
Placer Deposits
Magnetic Reversal
Crustal Thickness
How Diamonds are Made
Glaciation Issues
Mineral Transport Index
Doing the Map Work
Gathering Samples
World Mining Index
Excavation and Recovery
Mining Corporations
Mining News Magazines
Environmental Issues
Diamonds in Space
World's Only MineCam
Live Volcano Geo-Cams

EXPLORATION
Site Exploration History
Topography Map Index
Location Map
Claim Maps Index

DIAMONDS
Diamonds and Graphite
Diamond Formation
Grading Diamonds
Price of Diamonds
Industrial Diamonds
Drilling Equipment
Medical Use of Diamonds
Gemstones
Birthstones
Hall of Fame

DIAMONDS IN CULTURE
Good Books on Diamonds
Cremains to Diamonds
Diamonds in Lawsuits
Irish Diamonds
Unusual Diamond News
Diamonds in the Media
Famous Jewelers
In Advertisements
Top Twenty Cut Diamonds
Top Diamonds
Diamond Lore
Theft/Hoaxes/and Fraud
Religion Index
Diamond/ Culture Index
Television
Movies
Games - Play Now
Music
Weddings
Royals
Our Darlings
Diamond Animal Index

INTERACTIVE
Reflection/Refraction Index
Crossword Puzzle Index
Which Is A Diamond I
Which is a Diamond II
Become a Gemologist

The Process in Brazil

The Janio Matos target is located on the East side of the Araguaia River, in Goias State, between the towns of Aragarças and Baliza. The exploration work in this area included line cutting, topographical surveys, ground penetration radar surveys, geological mapping, auger drilling, large diameter drilling, bulk sample pit excavation, gravel processing and diamond classification/evaluation. The ground penetration radar survey data outlined a NE-SW paleo channel and the auger and large diameter drilling programs were essential in checking the ground penetration radar interpretation and verifying the gravel layer presence and the over burden thickness. Two large pits were then excavated to collect bulk samples from the gravel layer; the first pit (Janio Matos 1) was located close to be the center of the interpreted paleo channel while the second pit (Janio Matos 2) was located at the paleo channel border/edge. The bulk samples collected at the two pits were processed at a gravel processing plant comprised of a grizzly, screens, "resumidora" and sluice box. The processing plant was built to process 7.5 cubic metres per hour of gravel, although earlier tests concluded that the best recovery results were achieved at a process rate of 4 cubic meters per hour. Due however to Janio Matos 1 sample peculiarities such as clay mineral content and the excess of heavy minerals, the plant was forced to be operated at a much lower processing rate to avoid losses. The final concentrate went through a second hand screening process and the diamonds were recovered manually. The final clean up was done on a grease table so as to recover the smaller stones.

dry washing:
extracting gold from dry gravels, usually by equipment which uses air bellows for separating lighter from heavier material.

drywasher:
a common desert mining tool. the drywasher is like a highbanker but lacks the need for water. a drywasher operates by the use of wind. the light junk material is blown off the top of the sluice in the drywasher and the gold stays on the bottom. the sluice riffles in a drywasher are backwards for better recovery.

Recovery of Gold vs. Recovery of Diamond
Recovery in Placer-mining Operations

Sluice and wash plants used for gold recovery in typical Alaskan placer operations are not satisfactory for diamond recovery and prospect evaluation because of the relatively low specific gravity of the diamond (3.5) vs. gold(15-19) and many other heavy minerals.

Although alluvial diamond deposits can be extremely rich (for example,500 ktjton, according to Orlov, 1977), most diamond-bearing gravels contain diamonds in much lower concentrations. Realistic examples of rich, large-volume alluvial diamond deposits are those adjacent to the Argyle AK1 diatreme in western Australia ) which average about 3.5 kt/ton (about 1.5 yd3). Considering the relative richness and mineability of these deposits, it is clear that a reliable placer evaluation program will involve sampling and processing large-tonnage samples (hundreds or thousands of cubic yards) to obtain a valid assessment of diamond concentration and grade.

Alluvial Diamond Recovery Plants

The cleaning and sizing capabilities of wash plants offer an efficient and quick solution to discarding oversize material (>I/2 to 3/8 in.), cleaning and preparing bank-run material for processing by jigs and heavy-media plants.If grease tables are used for the final extraction of diamonds from concentrates, it may be necessary to 'prep' the concentrates with an additional abrasive wash to insure that the diamonds, if present, are free of surface coatings that may cause some diamonds to pass the grease table.

Various jigs are commercially available that are satisfactory for the recovery of heavy-mineral concentrates from diamond-bearing gravels. Anotheroption is the use of so-called 'heavy-media' plants that have been successfully used in diamond exploration in western Australia. These plants mix clean, sized material with a slurry of ferrosilicon prior to circulation in a cyclone. The heavy fraction sinks through the ferrosilicon medium, which is then magnetically recovered and returned to the circuit.

Concentrates from either type of plant (or both) can then be passed over a table or through an X-ray sorter. Another option for very small-scale evaluations is heavy-media separation using methylene iodide (sp gr = 3.2), visual identification with a binocular microscope,and hand picking of indicator minerals and diamonds.