Function Of Activated Carbon For Gold Mining

Activated carbon is widely used in the absorption of gold cyanide complexes in gold processing. This process can be applied to the clear solution through a fluidized bed column or participate in the process of leaching on the tank and the separation of carbon. Activated carbon in the cyanide process gold or commonly referred to as activated charcoal is charcoal made ​​from coconut shell charcoal, charcoal or wood or coal. The most widely used is granular activated carbon from coconut shell charcoal. With specific processing of the activation process such as treatment with high pressure and temperature, can be obtained activated carbon has a surface in the area. Glanural activated carbon derived from coconut shells are produced by pirolis with temperature 600-900 degrees Celsius by using an inert gas (argon or nitrogen) or by oxidation or combustion.
Adsorption of gold complexes (especially ion disianoaurat) on activated carbon is the basis of modern techniques for gold extraction process. This process is very effective and has become a major factor in improving the productivity of the gold mining industry over the last 25 years (S., Mansooreh, Tahereh Kaghazchi, 2007). Carbon is very actively used in the process of recovery of dissolved gold, either by introducing direct to the CIL (carbon-in-leach) or CIP (carbon-in-pulp) tanks after leaching. Activated carbon adsorbs dissolved gold from gold leach pulp complex to be absorbed through the pores of the carbon.The most cost-effective process is to create adsorption of the dissolved gold onto activated carbon, resulting in an Easier solid-solid separation based on size To Achieve this ore particles must typically be Smaller than 100 μm while the carbon particles must be larger than 500 μm. Adsorption is achieved by Contacting the activated carbon with the agitated pulp. This can be done while the gold is still being leached with the CIL-process, or following leaching with the CIP-process. The CIL-process offers the advantage of Countering the adsorption of gold on carbonaceous or shale ore particles, but is more expensive due to less efficient adsorption, Increased gold inventory and Increased fouling and abrasion of the carbon. 
Activated carbon in contact with a pulp containing gold can typically recover more than 99.5% of the gold in the solution in 8 to 24 hours, Depending on the reactivity of the carbon, the amount of carbon used and the mixer's efficiency. The loaded carbon is then separated from the pulp by water or screens That are swept hydrodynamically, thus Preventing blinding by the near sized carbon particles. The pulp residue is then either thickened to separate the cyanide containing solution for recovery / destruction of the cyanide, or sent directly to the tailings storage facility from the which the cyanide containing solution is recycled to the leach plant. 
       The gold adsorbed on the activated carbon is recovered from the carbon by elution, typically with a hot caustic aqueous cyanide solution. Gold was obtained by the method of cementation or by elektrorefining of the solution, while the carbon can be reused. Activated carbon can be reused by washing with dilute hydrochloric acid (HCl) to remove metallic impurity and neutralized with caustic soda. Reactivation is then performed first using a rotary kiln at a temperature of 730 degrees Celsius for 20 minutes. Generally, 10% of carbon lost in the process due to abrasion. During the process, the performance of carbon has decreased so that the efficiency of carbon sequestration need to be monitored and if necessary the addition of new carbon. In traditional mining usually carbon that has been filled with gold complexes directly in the fuel. Dust from the burning of carbon was then taken to be melted. Contained metal can be purified directly. This is done because of cost considerations and technology.When carbon is not used to adsorb the gold dissolved in the above-Mentioned leach slurry, the gold bearing solution must be separated from the solids components utilizing filtration or thickening units. The resultant solution, Referred to as pregnant solution, is subjected to Further treatment (other than by carbon absorption) to recover the dissolved gold 

Gold By Cyanidation Leaching Tank

Cyanidation with a tank on mining has increased rapidly since the mid-1980s. Extraction of gold by using a tank leaching systems typically use a lot of multiple tanks in series within a building. Different from heap leaching are located at the open air. Gold leaching process carried out by stirring the gold ore is mixed with limestone and added with a solution of cyanide in a tank and aerated with air bubbles. The duration of stirring often for 24 hours to produce the optimum leaching. Tank and leaching efficiency of about 92% to 98% gold content of rocks

Gold is one of the noble metals and as such it is not soluble in water. A complexant, such as cyanide, which stabilizes the gold species in solution, and an oxidant such as oxygen are required to dissolve gold. The amount of cyanide in solution required for dissolution may be as low as 350 mg/l or 0.035% (as 100% NaCN). Alternative complexing agents for gold, such as chloride, bromide, thiourea, and thiosulfate form less stable complexes and thus require more aggressive conditions and oxidants to dissolve the gold. These reagents present risks to health and the environment, and are more expensive. This explains the dominance of cyanide as the primary reagent for the leaching of gold from ores since its introduction in the later part of the 19th century.
On cyanide leaching of gold in the tank system, activated carbon is very important to use when in the process of recovery of dissolved gold, either by introducing direct to the Carbon In Leach (CIL) in tank or to the Carbon In Pulp (CIP) separately outside the tank after washing. Carbon In Pulp (CIP) leaching  occurs in two stages in the process in a different tank, while the Carbon In Leach (CIL) slurry of minerals and activated carbon having a tank leaching simultaneously on the same premises. Carbon is then separated from the slurry by screening and have further treatment to recover adsorbed gold.Gold complexes of carbon absorbed directly as soon as the gold dissolves in cyanide solution. CIL is used if the rock contains a lot of natural carbon, because carbon will naturally absorb the gold complex. Add activated carbon in the CIL is more active than the natural carbon.CIL investment cost is less expensive when compared with the CIP so that this method is also used on many people's scale mines are. This method is higher than the absorption of gold compared to the Heap leaching. New technologies are applied in South Africa using ion exchange resins Resin In Pulp (RIP) is expected to lower the operational costs. Preparation of rock (including softening, solution concentration, as well as the type of solution) and the leaching time is different for each rock. Oxide rocks the size of 65 mesh requires a 0.05% NaCN (50% solids) with a leaching time of 4 to 24 hours. Sulfide rocks the size of 325 mesh needs 0.1% NaCN leaching time up to 72 (Weiss 1995)

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The process of Acid Treatment on gold is very important to do before continuing on gold metal smelting processes, due to deposition of the cementation process is done is still a lot of metal-containing zinc, iron and lead are also entrained. Acid Treatment is a process of dissolution of metals such as zinc, iron and other metal impurities using dilute sulfuric acid (H2SO4).From this process of acid treatment will be easier to concentrate smelting process before the stage of purification to make pure gold, because the metal impurities such as zinc, iron and other impurities that integrates with the content of gold ore has been dissolved by the liquid sulfuric acid (H2SO4). In the use of dilute sulfuric acid (H2SO4) is a blend of metal impurities will easily soluble by dilute sulfuric acid (H2SO4), is a metal that has a positive electrode potential in electrochemical series is rather difficult to dissolve, because the greater the tendency to become ions, and vice versa. A metal with a more negative potential shifts the metal underneath any of the salt solution.
      The same thing applies when reacting sulfuric acid with potassium nitrate. This reaction will produce nitric acid and precipitate potassium bisulfate When combined with sulfuric acid nitric acid behaves as an acid as well as substance to dehydrate, forming nitronium NO2 + ion, which is important in nitration reactions involving electrophilic substitution aroma. Reactions of this type is very important in organic chemistry. Sulfuric acid reacts with most metals via a single replacement reaction, which produces hydrogen gas and metal sulfates. Dilute H2SO4 will attack the iron, aluminum, zinc, manganese, magnesium and nickel, but reactions with tin and copper require hot sulfuric acid and concentrated. Lead and tungsen not react with sulfuric acid. The reaction between sulfuric acid with metals normally would produce hydrogen as shown in the equation below. But the reaction with tin dioxide than will produce hydrogen sulfide.

Fe (s) + H2SO4 (aq) H2 (g) + FeSO4 (aq)

Sn (s) + 2 H2SO4 (aq) SnSO4 (aq) + 2 H2O (l) + SO2 (g)

Diagram Of Gold Mining Processing

Gold mining was first carried out in alluvial areas. Processing system is also very simple to do that is by panning using a tray, which then developed with gold mining wave table, and followed by gravity separation method using the amalgamation process with the capture of mercury. Gold exploration in the lower layers of soil to get the primary sediment deposits began in 1860 with gold using a cyanide treatment system. And in 1960 the method of processing low-grade gold began being applied, which carried out the processing system through leaching heap, this process is basically developed from gold processing system using cyanidation . Of all the gold mineral processing must go through several stages in all these stages it is absolutely live to get the desired results, as for some stages it can be underlined by the diagram below


Zinc Precipitation Stage Of Gold Deposition

     Metal deposition method using Zn powder (Zinc precipitation) was first introduced by Sulman and Teed (1895). Basic usage of this method is the electron affinity of zinc metal is much higher than in metals gold and silver, then gold and silver metals will sink and be replaced by a soluble zinc. The Precipitate that occurs will be shaped cement sand. Although the use of activated carbon is used widely but many are also used primarily cementation in rocks that contain lots of silver because the cementation is a process very simple and very inexpensive.

Function The Mercury In Gold Processing

Mercury (Hg) is one type of metal found in nature and are scattered in the rock, ore mines, land, water and air as inorganic and organic compounds. Mercury is one of the basic elements of chemical and heavy metal is a liquid which under normal circumstances silvery, not smelling with a molecular weight of 200.59. Mercury is not soluble in water, alcohol, ether, hydrochloric acid, hydrogen.History of Mercury has been found in Egypt in ancient tomb relics century 1500 BC, and may be used for cosmetic and medicinal purposes. Around 350 BC, Greek philosopher and scientist Aristotle explains how to take the mercury by heating cinnabar rocks for religious ceremonies. In Rome, mercury is used for various purposes and give it a name hydrargyrum, which means liquid silver into the origin of the chemical symbol for mercury is Hg. Mercury Amalgamation was first to cultivate the patio process of silver by the year 1557 in Mexico who made ​​the request of mercury is greatly increased. Mercury barometer was invented by Torricelli in 1643, followed by the discovery of the use of mercury in the thermometer by Fahrenheit in 1714.
Known For Three Forms Of Mercury, Namely:

How The Gold Amalgamation Process

The process of amalgamation is the gold processing is a very simple process of mixing between gold and mercury (Hg). Amalgamation Technique performed by mixing rocks containing metallic gold and mercury by using a drum machine tools. Amalgamation of Gold Processing techniques are mostly done by small scale miners and simple. In processing system that uses gold amalgamation technique is desperately needed water, where the function is to separate the water between the rocks that have been refined and amalgam, which will result from amalgam mud in the pool will be at capacity reservoirs.
Some simple steps that are used in gold processing system amalgamation with drum machines are as follows:
  • Destruction of rocks from the mining conducted to obtain a smaller-sized rocks. Size obtained is usually ± 20mm. machine used is a machine or Stone Crusher Hammer Mill or Crusher Jaws
  • Rocks that have been destroyed then in put in drum machine with a capacity of drum machine used. In order to rarefaction and binding of the metal content of gold by mercury can then be left up to a quarter of the capacity of drum machine used. After all the rock mineral inserted it inside the drum machine was added to the water a quarter of the above rocks are included.
  • After all is ready for mashed inside the drum machine drum machine can be closed up tightly so that no liquid water in the machine until it comes out. Then let the mill running until approximately 4 hours or 5 hours. Until all the soft rock material such as flour.
  • After all the rocks are soft, then the mercury can be inserted into the drum machine, then run the machine back to the time between 2 hours. To 25 kg of material processed mineral rocks better use of mercury 2 kg
  • After all completed then all the mud from inside the drum machine is issued and placed in a large tub and on the inside of the drum machine can be sprayed with water, so that the remains of mud and Mercury are still attached to really clean the drum machine
  • Then the mud bath that contains you fill with water until it is completely full and overflowing from the tub of mud mixed with water will flow into the storage pool, whereas the binding of mercury amalgam will settle to the bottom surface of the tub. The addition of water is continuously performed very well, because when mud is thickened mercury can be carried away by the thickened sludge  
  • Amalgam that has been generated can then be filtered and squeezed using a parachute cloth until all the mercury out of the parachute fabric, it will produce the mineral content of ores that have tied up with mercury. Amalgam that has been generated and then decomposed into elements of mercury in gold bullion by heating the distillation because mercury will evaporate and be recouped to the condensation of mercury vapor that can be reused.     
Besides the distillation is another method that can be used to separate between the amalgam and mercury amalgam is by dissolving with nitric acid obtained by transformation of the reaction as follows:

HgAu 2HNO3 + -> Hg (NO3) + H2 + Au
Occurred after the deposition of gold in the form of foam, conducted separation nitrate solution. Mercury can be taken by the displacement of copper ions or other metal ions that have a more negative electrode potential of the mercury, by the reaction:
Hg (NO3) 2 + Cu -> Cu (NO3) 2 + Hg
Noteworthy in this method is contained in the silver content of mercury can reduce the infiltration. Periodically need to be done purification by distillation.
  • The results of the distillation process that has been split between the metal containing gold with mercury it can be readily Processed Fusion.
Furthermore, the solution in the form of mud that has been deposited in the pool, when it has dried transported to re-processed using the Cyanide (NaCN), Because of the efficiency of processing the results of amalgamation technique can only reach 60%. 

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Gold Processing Techniques In a Way Amalgamasi

The processing of gold-making Amalgamation is a process of extraction of gold in rocks containing the gold content of ore by using a chemical binder Mercury (Hg) as a catcher ore minerals. This amalgam process is the most simple and cheapest is usually used by small-scale miners, but on a large scale is not very effective and very expensive. The use of mercury in amalgam process was first used in 1828, despite the widespread use of new techniques is prevented due to the toxic nature of mercury. Around 1895, experiments conducted by GV Black showed that amalgam is safe to use, although 100 years later, scientists are still debating
         In the  Process Of Amalgamation is a common tool used is the drum machine as a means of smoothing the rock minerals and metals by mercury capture elements in rocks that are processed. This process is a process of chemical physics, product formed is the bond between the gold-silver and mercury are known as amalgam (Au - Hg). Mercury will form amalgams with all metals except iron and platinum. when the amalgam is heated, it will break down into elements of mercury and alloy. Amalgam can be decomposed by heating in a retort, the mercury will evaporate and can be recovered from the condensation of mercury vapor. While the Au-Ag still remained in the retort as a metal.
        Extraction Of Gold in the Process Of Amalgamation will be effective on the liberation of gold that were wholly or partly on particle size greater than 200 mesh (0074 mm) and in the form of pure gold that is free. The success of the processing of gold by amalgamation system is determined by the condition of metallic minerals from the ore in the pulp and conditions though. Conditions that cause ugly gold metal grains can not be wetted by mercury and can be divided into fine particles so that the process of amalgamation does not take place perfectly. Gold grains derived from primary gold ore is not oxidized is usually clean and shiny is good to get into the mercury in the process of amalgamation. And another thing to consider in this process is the element content of the oil carried by the ore is very disturbing in the process of amalgamation and can break down the content of mercury, so that mercury will be small grains and is often carried away by the tailings. Oil contamination can also be caused by oil from machine tools. If the oil spill to occur on mineral ore, it can be done roasting minerals that will advance the process. Or can also add cement or lime.

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How To Use The Gold Consentrate Smelting Furnace

Smelting is a form of extractive metallurgy whose function is primarily to produce a metal from ore company. Where this smelting process uses heat and Chemical reducing agent to change the state of oxidation of the ore in the furnace furnace. Furnace equipment has a role as a source of heat transfer the heat generated from fuel combustion reaction by Burner in the fire box, whether it be a Fuel Gas, Fuel Oil or other types of fuel with air, whereby heat generated was transferred into the crude oil flowing in the tube. In the process of smelting ore concentrate in the form of fine sand that has a metal content of gold, silver, copper and minerals that contain other elements, then there are three stages of the smelting process used.

The first process Smelting Furnace:Ore concentrate that has been generated from a given mining with SiO2 flux. The results of this concentrate is introduced into the furnace heat furnace with high temperatures between 1200 degrees Celsius and air flow are given, and usually free air compressor with 60% oxygen regulated. The purpose of this air is to oxidize the main impurity element in the form of Fe. From oxidation to FeO and Fe3O4 and starts cutting sulfur in the concentrate into SO2. The results from the smelting furnace and into the slag Cleaning
Slag Cleaning here are still a molten Cu Matte sulfur content because they are still a lot to be separated with the slag formed from the first process. In this process will use electric arc furnace. so the heavier matte and slag will be below the float, still heated. Here is a separate metal slag. To eliminate the sulfur content will be through the process of converting furnace
Converting Furnace In this process air is blown matte longer wear and additional ces flux limestone (CaCO3), because its main purpose is to oxidize sulfur, and using lime to keep the composition of the slag so as not to thick, very solid because of Fe3O4 can not be blown up with air.. After going through the process of converting the sulfur has begun to slow (0.8%) and are called blister copper is not a matte. Then proceed into the Furnace to print a Cu anode blister because it requires electrowinning for subsequent process steps.

These few examples of simple equipment for metal smelting :