Monthly Archives: January 2012

Mercury In Gold Mining

    Mercury is denoted by Hg, an acronym of Hydragyrum which means liquid silver. Mercury is a metallic element which is in group II B in the periodic system, with atomic number 80 and mass number 200.59. The metal mercury is produced naturally and is obtained from ore processing, Cinabar, with oxygen (Palar; 1994). The metal mercury is produced, used in the synthesis of inorganic compounds and organic compounds that contain mercury. In everyday life, mercury is in three basic forms, namely: metallic mercury, inorganic mercury and organic mercury. 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:

1.  Elemental mercury (Hg) contained in glass thermometer, tensimeter mercury, dental amalgam, electrical equipment, batteries and paint rocks. Also used as a catalyst in the production of caustic soda and disinfectants as well as for the production of chlorine from sodium chloride.
2.   Inorganic mercury: in the form of Hg + + (Mercuric) and Hg + (Mercurous) For example:

– Mercury chloride (HgCl2), including the form of inorganic Hg is highly toxic, caustic and
used as a disinfectant
– Mercurous chloride (HgCl) which are used for teething powder and laksansia (calomel)
– Mercurous fulminate which is flammable.

3.   Organic mercury: present in some form, al :
– Methyl mercury and ethyl mercury which both include short chain alkyl forms encountered
as metal contaminants in the environment. For example eating fish contaminated with TSB.
– Can cause neurological and congenital disorders.  

         Mercury is very useful in the processing of gold and silver. This also encouraged to develop mercury ore deposit in the United States after the discovery of gold and silver in California and other western countries in the 1800s. Mercury is widely used in various industrial products and applications after 1900. He used to be used in batteries, paints, explosives, light bulbs, the light is on, pharmaceuticals, fungicides, and pesticides. The main application for the production of chlorine and caustic soda, and as a component of electrical devices, including fluorescent and mercury-vapor lamps. Mercury is also used as part of the process for the manufacture of paper, felt, glass, and some types of plastics
A good use of mercury in gold processing system:
1. Avoid contacts with mercury when you’re doing the processing of gold, try to use any such protective rubber gloves.
2. Keep mercury is always in place a sealed like plastic bottles, metal or glass (not the container of aluminum).
3. Always add water above the liquid mercury, except for mercury which has been recycled or that have been used in gold processing.
4. Do not let spilled mercury because it is very difficult to clean it and take it, because mercury can be as small droplets of water that spilled ..
5. Mercury should not be one with other chemicals, put mercury on a separate room.
6. Using equipment that supports the safety and health.
7. Do not eat or smoke when using mercury.
8. Use just enough mercury. 
 How to clean up after Mercury used in gold processing.
Soak mercury in solution with the composition coustic soda per 1 kg of Hg was washed with a solution of 30 s / d 50 g coustic soda in 1 quart of water. Or it could be with the addition of salt.
Mercury storage
Although mercury has a boiling point of 357 ° C, but has the ability to evaporate at room temperature (25 ° C) due to the low-pressure evaporat
   To avoid evaporation:
1. Save the mercury in the shade (room temperature> 25 ° C) and protected from direct sunlight.
2. Store in a special container (can use containers made of stainless steel, steel, iron, ceramic, plastic or glass container and do not use aluminum) are closed and make sure the mercury soaked with a little water, and put it in a safe place away from the child.
Impacts Of Mercury
The effect of mercury toxicity to the body include: nerve damage, including being grumpy, paralysis, blindness or mental disorder, chromosome damage and malformed baby in the womb. mild symptoms of mercury poisoning is depression and anger like that is the nature of mental illness, headaches, difficulty swallowing, blurred vision, with a declining power, feels thick in the legs and hands, the mouth was blocked by metal, gum swell and accompanied by diarrhea, weak body, and defects in human fetuses. Mercury in high concentrations sometimes in getting in the waters and fish tissue derived from the formation of ion monoetil mercury-soluble, CH3Hg + and the (CH3) 2 Hg, by anaerobic bacteria in the sediments, mercury from these compounds become concentrated in fatty tissues fish (biological amplifier) can reach 103. As a result of the strong interaction between the mercury and other soil components, the replacement of mercury from one form to other than the gas is usually very slow. Methylitation mercury process usually occurs in nature under limited conditions, forming one of the many dangerous elements, because in this form of mercury is very easy to accumulate in the food chain. Because of harmless, the use of alkali mercury fungicide in hatcheries are not permitted in many countries.

Amalgamation Process Gold

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.

How The Gold Amalgamation Process
The amalgamation process gold is a very simple process from the processing of gold, that is by way of mixing between mineral rocks of gold and mercury (Hg). Amalgamation technique performed by mixing rocks containing metallic gold and mercury by 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 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.From the distillation of amalgam can then be directly smelted and made ​​into a metal, and of course there are mineral deposits of silver and copper metal.

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%.

Reagent Flotation

Flotation reagent is the most important thing in a flotation process, in which this reagent is needed for removal of mineral concentrates that will be done. Basically the flotation process depends completely on the adhesion properties of certain minerals to air (hydrophobic), and to water (hydrophilic), and therefore the addition of chemical substances in the form of reagent. Any one of various chemical substances that govern and regulate most flotation processes. The introduction of flotation reagents into the liquid phase of the pulp and subsequent adsorption along the liquid-gas and solid-liquid interfaces create conditions for the selective flotation of specific mineral particles. There are three principal types of flotation reagents: collectors, regulating agents, and frothing agents.


Xanth (ogen ) ates Sulfide Flotation
Dithiophosphates Sulfide Flotation   
Carboxylates ( Fatty acids ) Carbonate / Oxide / Sulfide Flotation
Dithiophosphates Sulfide Flotation   
Alkyl ammonium salts Silicate / Oxide Flotation

Aliphatic alcohol ( Methyl isobutyl carbinol ) Frother
Cyclic alcohol ( Pine oil, Eucalyptus oil ) Frother, Collector
Aromatic alcohol (Cresols, Xylenol ) Frother

REGULATOR ( Modifiers ) FUNCTION       
Lime (Dalkeith) Sulfide pH – Depressor phyrite
Sodium hydroxide pH-Disperses gangue
Sulfuric acid pH
Copper Sulfide Sphalerite Activation
Sodium Sulfide Activation /Oxidation
Cyanide Depressor Sulfide
Chromate Depressor Galena
Reagent used in the flotation process can be classified into:
  • Collector

Collectors are organic substances that impart hydrophobicity to mineral particles to be floated, which makes possible the attachment of the particles to gas bubbles. Collector is a material that can cause mineral particles into the air like it, namely by coating the surface of mineral particles with a polar reagent. So on the outside of the minerals that make up the chemical reaction occurs non-polar layers are easy to draw the air, and minerals, it easily attaches to air bubbles. The molecules of a collector are generally composed of two parts: (1) a hydrocarbon (nonpolar) and carboxyl group and (2) an amino-acid group and another (polar) chemically active group affixed to the mineral surface. Collectors are classified as nonionogenic and ionogenic according to their ability to dissociate into ions in an aqueous medium. Nonionogenic collectors are virtually insoluble in water and usually include nonpolar, hydrocarbon liquids, such as kerosine and petroleum oils. Ionogenic collectors dissociate in water into an anion and cation and, depending on the type of hydrophobic ion, are divided into anion collectors
Sample collectors for sulfide minerals are Xanthate, and Dithiophosphate. As for non-sulfide minerals Fatty acids are saturated and unsaturated.

  • Frother

Frother chemical to use to help stabilize air bubbles that form on the flotation process, so it is not easily broken. Air bubbles that are formed should be able to move freely in the pulp and can take precious mineral particles, and then float into the pulp.Frothing agents increase the stability of the mineralized froth and facilitate the dispersion of air in the pulp and the formation of the minutest possible bubbles. Such agents are usually organic surfactants, the molecules of which have a polar and nonpolar group and are adsorbed along the surface of the gas-liquid interface, thereby reducing surface tension
Examples of Flotation frother frother is DOWFROTH Series, MIBC, and Polyalkoxyparaffins.

  • Modifier (modifying agent)

Modifier is used to return to the original surface properties. The goal is to improve the selectivity in the flotation process. Modifying agent can be grouped into 3 kelompo, namely:

1.   Regulating and Dispersing Agent 
Regulor serves to control the pH, eliminating the influence of slime disruption, colloid, and sea salt. An example is CaO, Na2CO3

Dispersing Agent serves to release the slime on the surface of minerals.
An example is Na2SiO3

2.   Activators

Aims to increase the activity of mineral surfaces in order to interact with the collector, so the collector adsorbs on the particle surface for the better. An example is the Cu + + to float sphalerite, and Ca + + for quartz float.

3.   Depresant
Prevent flotation of certain minerals without blocking other mineral flotation. Used when the float ability unwanted minerals float together with the minerals that will float by certain collectors. An example is the CN-(pyrit, sphalerite), and Zn + + (sphalerite)