Gold Mining

Gold mining means the retrieval of gold from the ground. Gold is a largely nonreactive metal, and for that reason it is found in the earth's crust almost in a pure state. It is obtained in the earth and in the bedrock that is found in the earth's crust. Though gold is found in its virtually pure state in the earth, it is a challenge to find out where it is present and to extricate it from the earth.

There are many methods that are used for removing gold from the crust onto the earth. The crudest method and even the most common is the gold scanning technique. This is a method in which the earth that is supposed to contain gold is placed on a shallow pan and scanned. Water is added to this and the floating impurities are removed. The principle is that gold is a metal and so it will sink at the bottom. Gold pieces, if any, are found at the bottom. This was the method amateurs used in the various gold rushes around the world. And some of them did return home with a rich bounty of gold in their pockets.

Of course, a method like scanning gold after adding water to its earthy mixture cannot be implemented on an industrial method. These methods are usually implemented for gold that is deeply embedded in the rock of the earth. An example of this is the open pit method which is described below:-

• First, using various techniques the presence of gold is ascertained. For this, methods such as using metal detectors or taking satellite images are employed.
• Once the images are taken, high precision computers are used to ascertain at what depth and in what quantity the gold is present. This is important for ordering the right kind of equipment.
• It is also important to take all necessary governmental permissions at this point.
• Then the mechanical gold mining process begins. In this, a heavy vehicle with a drill fitted on it is driven to the spot. This drill is made vertical by a motorized machinery attached to the truck, and a hole is bored.
• The preliminary ore is extracted and is sent to the labs for checking its quality and also to ascertain whether the gold mining at that spot will be indeed a profitable activity.
• Once that is done, several more trucks are driven to the spot, all with drills on them.
• If the gold obtained is of high quality, then it is sent to a mill where it is ground to powder. From there, if needed, it is purified by roasting up to 1,000 degrees Fahrenheit with carbon, or cyanide processing, or is oxidized in an autoclave with sulfide.
• The cyanide processing is the most significant processing step. Here, even if the gold is of poor quality, it is treated by this method and high-quality gold is obtained.

Cyanide Processing in Gold Mining

Cyanide processing is used in gold mining when the gold obtained is of an inferior quality. Due to the very precious nature of gold, it needs to be purified to a very high grade. This is where the method of cyanide processing becomes important. This is how it is done:-

• The mined gold of the inferior quality is broken into small pieces and then kept on a pad that has grooves in it to place the pieces of gold.
• Then a dilute solution of cyanide is introduced onto this pad.
• The cyanide will dissolve the gold in it. This solution is collected. It contains the pure gold.
• This solution is passed over activated charcoal. The gold pieces will get adsorbed onto the activated charcoal, and that can be separated through further processes.
• The carbon with gold on it is either physically stripped from the carbon, extracted as a precipitate obtained after an electrolytic procedure.

The pure gold which is obtained after all these processes is then cast into small bars. These bars are further processed in refineries to get 90% pure gold.