Hobbies And Interests
Black Sand Concentrates
Save your black sands. Whether you are mining using a gold pan, a sluice box, a high banker or a gold dredge, you will end up with a large quantity of black sand concentrates. With luck, these concentrates are rich in fine flour gold or small, almost invisible flakes. These exceptionally weighty sands are composed of a unique combination of heavy metals, predominately pyrite, garnet, magnetite, ilmenite and chromite. A cubic foot of black sand will weigh approximately 220 to 240 pounds or about 25 to 30 pounds per gallon. Recovery of the microscopic gold they contain is a perplexing problem for the modern prospector.
Remember to always separate and label your black sands. Do not mix sand from different prospecting locations together. You can store your concentrates in old coffee cans, plastic containers or 5-gallon buckets. The preferred method is to purchase ore sample bags from an oil field supply or mining store. These cloth bags will allow the moisture to evaporate from your concentrates, yet will not allow any of the fine sand and minerals to be lost. The bags have tags for site location, date and mining notes. A dried bag of concentrates is a lot lighter than than a bucket of wet "cons" and much easier to handle.
When processing your concentrates or sending them to a professional testing facility, it is imperative to know the exact location they came from. If the concentrates yield an impressive amount of fine gold, you will want to return and work that location again.
Comercial Recovery Methods
Cyanide leaching is the standard method for recovering gold from large volumes of ore in commercial mining operations. Cyanide, a powerful lixiviant, forms a stable complex with the gold and separates it from the gangue that surrounds it. Cyanide is toxic and is not a method that can be used by the recreational prospector.
Amalgamation is another method of fine gold recovery suited for large commercial mining operations.
Basic Recovery Techniques
Spread your dried concentrates out on a large piece of white paper. Work with just a couple of tablespoons of concentrates at a time. Using a pair of needle-nose surgical tweezers, pick out any visible tiny nuggets or flakes and transfer these to a glass vial for storage.
Next, wrap a magnet with a layer of clinging plastic wrap. Move the magnet gently through the concentrates. The magnet will pick up magnetite particles for disposal. Just remove the cling wrap from the magnet, and the particles will fall away. The gold will remain on the paper and can easily be transferred to a storage vial. Fold the paper to form a crease and carefully pour the gold particles into a vial. Do this over another piece of paper in case you should spill a few flakes.
Mechanized Recovery of Fine Gold
If you have a large amount of black sand concentrates to process, consider one of the dozens of mechanized small concentrators available to the recreational gold miner. Mini-sluice boxes, centrifuge concentrators and wheels are popular. Visit a local mining store and request brochures and demonstrations of the many different models before choosing the one that is right for your application.