Different types of Extraction Method of Gold
Scientists have developed a new way of extracting gold, which reduces the production cost of this precious metal by over 40 percent and considerably decreases the amount of time required to do the process.
Although precious metal gold just occurs hardly indeed, it is found everywhere in this world in 16 km thick Earth’s crust. However, the amount of gold present on earth is very small, so mining isn’t very worthwhile. Normally, there are 2 kinds of gold: one is primary gold (“or mountain gold” from the mines) and another one is secondary gold (“or stream gold” and “nuggets”). Above all different extractions of the primary gold is linked with the considerable effort.
There’re different methods to free these gold particles from the solid mantle in the ore extracted underground. Most important of them is described here.
Methods of Extracting Gold
The Cyanide Leaching Extraction Method
This process of the cyanide leaching is primarily used where earth has a high concentration of gold making the industrial development worthwhile. And for this procedure gold-bearing rock has to be crushed to dust. Subsequently, rock dust is piled in heaps, stored or columns in tanks –are combined with the sodium cyanide solution. This acid separates the gold from rock dust and then transports this in an acid seepage fluid to a bound form. Subsequently, gold gets filtered from the leach solution just by adding a little zinc dust, and washed out from the muddy substrate and dried out. This recovered gold is then refined into fine gold. Some major reservations do exist against this process of extraction because of the release of poisonous, and easily flammable cyanide acid that presents some significant risks for the human beings and environment as well.
The Amalgam Extraction Method
The amalgam process is one oldest technical process of extracting gold as well as was used in ancient times. In this amalgam process gold bearing rock gets crushed to sand. Than mercury is added into this rock dust and gold has an amazing property that allows it to join any mercury surface. Gold enriched mercury than forms the silvery shining alloy, so-called amalgam. This amalgam collects at the bottom of this mixing container and easily gets separated from other minerals. Consequently, amalgam is heated till the mercury completely evaporates, leaving only pure raw gold. But, this method involves some risks to health and environment experienced while vaporizing the poisonous mercury.
Electrowinning Extraction of Gold
Elecrowinning is in a meantime, one highly used procedure whereby gold gets extracted without any use of toxic substances. And this method uses the electrochemical approach. Benefit of this method is taken during the extraction of other metals like zinc or copper where some quantities of gold can be found in the extracted rock. In this electrolytic cleaning process of sludge the anode activates the metal bearing sludge. Cathode is made from the piece of metal. During the electrolysis, gold in a raw rock material isn’t dissolved and is collected as the sludge under the anode. Together with the gold other metals (Silver, lead, copper, tin) concentrate in the anode sludge and are skimmed off very easily. Then, using the suitable process the individual metal is separated from one another.
Removing any gold-bearing rock sludge from the surface ground is just an initial step. In order, to separate pure gold, mining firms use some complex extraction procedure. The first step in the process is to break down the large rock chunks into smaller pieces. At the mill, big machines known as the crushers decrease the ore in pieces not larger than the road gravel. This gravel like material enters the rotating drums that are filled with the steel balls. In the drums, the ore is extracted to the fine slurry and powder.
Next, the mill operators thicken this slurry with some water to form the pulp and run this pulp through the series of tanks. Leaching dissolves this gold from the ore by using special chemical solvent. The most common solvent known is cyanide that should be combined with the oxygen in the process called carbon-in-pulp. When the oxygen and cyanide react chemically, gold present in this pulp dissolves. When the workers introduce some small carbon grains in the tank, gold adheres to this carbon. Filtering out the pulp by screen separates this gold bearing carbon.
Borax Process of Gold Extraction
Borax process is the environmentally-friendly way to extract gold or any other precious metal. Here gold bearing rock is put in the melting crucible and borax (or sodium borate) is then added. Borax sinks in the melting stage of this ore mixture and then makes this molten mass fluid. Low melting point allows gold to get extracted by using the cost effective, and low power heat sources that will bring about melting. Gold sinks to its bottom of the crucible, while other rock material like quartz, silicon, ore and all oxides come on the top.
Some other processes that involve ground ore getting passed over the plates coated with mercury. Gold and mercury form the amalgam, and leading to the name of this process, amalgamation. When amalgam has formed, it’s heated until mercury gas gets boiled off, and leaving only pure gold. This mercury gas is very toxic and should be handled very carefully.
Another gold extraction method is flotation. The ore is put in the solution that has the frothing agent all along with the collecting agent and the organic chemicals. Frothing agent turns this solution into the foam. This collecting agent bonds the gold, and creating one oily film that can later attach to the air bubbles surface. Organic chemicals will prevent gold from getting bonded to other material. Then air is passed through this solution and gold laden film bonds itself to these air bubbles. Bubbles come to the top and gold gets skimmed off.
The scientists have tried to remove this with different technologies that were developed in the research labs, however, all these methods tuned out very economically inefficient. But, the technology on the basis of the ammonium cyanide proved this task.