gold panning

environmental impact

The industrial exploitation of the gold ore is an activity often highly polluting and contaminating the environment sustainably, even in Europe where this activity is not very known public1. In intensive farms golden soil and alluvium, as practiced in situ in tropical forests, the miners must merge the particles, dust or tiny sequins, using mercury, which is then extracted by heating and evaporation .

 These miners could still recover with a simple mercury evaporated, but they do it very rarely, and their entire mercury pollutes the environment. In ramps or "sluices", the very fine gold particles are brought into contact with mercury (the cleats of ramp) to amalgamate together. Some of this mercury is washed away with sterile or absorbed on organic matter and goes directly into rivers. The first by mercury poisoning are the miners who breathe the fumes when they distill. The rest of the mercury pollutes the air and the mist, dew and rain, soil and food chain (fish and shellfish in particular). Where ( in France) the amateur miners seek only sequins and gems, they have no need for mercury or cyanide.

Mercury is toxic (like all heavy metals), even at low doses and in all its forms. Note however that between sustainable food chains as its methylated form (methylmercury), the most toxic, produced by bacteria in anoxic conditions (standing water, sediment ...). This is a major pollutant of the environment, and one of those whose levels increase alarmingly in all compartments of the ecosystem. In areas where it is extensively practiced, gold mining is the main source. Mercury can be recovered by simple condensation, but this is rarely the case in the field.

• The techniques are also industrial waste polluting because they produce cyanide.
• On the other hand the use of pumps and powerful jets of water to disintegrate the soil and reduce mud that is mixed with mercury to extract gold is a source of pollution of soil destruction, by increased turbidity of the water, and the suspension of heavy metals or minerals naturally present undesirable but normally fixed in soils. 

In French Guiana, the soil is naturally rich in mercury (8 times more on average than European soil) increases this particular problem. In this case, even if the ban (effective since January 2006) was respected everywhere, use monitor nozzles would still be a source of significant pollution by mercury. Anaconda operations aim to fight against illegal mining.

Where can I find gold

Gold is found in gravel beaches, located in rivers. In these placer gold occurs as native particles are relatively big (millimeter flakes or nuggets) mixed sand and gravel.

The gold rivers comes from the disintegration of former mountain veins (veins detrital) in which he was to trace as veins of copper, iron, lead. Gold, because of its density, is also in pots that are rock crevices along the back of the riverbed.

Equipment for gold mining

To separate native gold alluvium, we use the gravity with the difference in density of alluvial gold (16 to 19 following the content of other metals such as silver or copper) sand (2).

Using different devices: The spray bar, or sluice Longtom is a channel made ​​of wood or metal, filled with carpets and special cleats which is caused to flow alluvium with a water stream. Gold is trapped or retained by the carpet behind the cleats while the sand is removed.

The trailing suction hopper dredger or "suction dredge" uses a pump to the alluvium in the riverbed or river, and pour on a spray bar placed on a raft.

There is a contemporary gold rush in French Guiana (overseas department (DOM) French), Brazil and Africa. In these countries, to recover gold, usually present only in tiny sequins and low in the alluvium of the major rivers, using barges and huge sucking the gravel with sucking in "sluices"

In France we use also of (small) suction dredgers but they are very common and its use is regulated, and any use of pump.

In France it also recovers gold by-product of sand.

• prospecting

It is the recognition and evaluation of economic placers. She is by techniques of hydrology and sedimentology and implementation of specific hardware.

• The technique of panning or pan

The pan is a pan that can separate the gold flakes in the sand. It is used to analyze the gold content of gravel and extract gold from concentrates obtained from carpets laid on a spray bar, a drag-suction or in a sand pit. The competitions are held washing gold on the dexterity of handling pans.