Chemical Use in Gold Mining & How to Buy Gold Recovery Chemicals

Role of Chemicals in Gold Mining, Processing and Recovery

At Camachem we assist gold mining companies source the right type and grade of chemicals for their gold mining process. In order to assist you source the right chemicals, we provide an overview of key gold mining and processing chemicals.

Extracting value of gold is not just about removing the gold-bearing rock from the ground. This is just the first step in the process of mining gold. Complex extraction processes are involved in the isolation of pure gold from the rock. First, the large chunks of rock are broken down. With the help of crushers, the ore is reduced to tiny pieces. It turns into gravel-like material and which is then entered into rotating drums filled with steel balls. The ore is turned into powder in these drums. It then goes through a series of hydrometallurgical or pyrometallurgical processes. Hydrometallurgical processes involve the use of aqueous chemistry for the extraction of gold. Whereas pyrometallurgical processes involves the use of heat for the extraction and purification of precious metals like gold.

In the gold recovery process are many chemicals involved. Xanthates are unsafe, Diphosphates are toxic and Leaching chemicals as well. The only chemical that may not be toxic for humans is pine oil, used as a frother.

Top Gold Producing Countries

The world has an insatiable hunger for gold. Every year around 2500 tons of gold is mined to be used for various purposes. The single largest use of gold is in the jewelry industry. Since pure gold is too soft it is alloyed with silver, copper, or both to achieve the required hardness and strength. Gold is also extensively used in dental bridges and crowns. For this purpose, it is mostly alloyed with silver, copper, platinum, or palladium to increase strength. Due to its properties of high electrical conductivity and corrosion resistance, it is used in the plating of electronic contacts, transistor bases, and semiconductor silicon chips. Its use ranges from dental fillings to satellites.

China is the leading gold-producing country, closely followed by the Russian Federation and Australia. Following is a list of top gold-producing countries and their annual gold production.

List of Top Gold Producing Countries and their Annual Gold Production

Source: World Gold Council

Types of Chemicals Used in Gold Mining

Chemicals are widely used in the gold mining processes. Every step of mining requires special chemicals for specific purposes. Typical gold mining processes are either hydrometallurgical or pyrometallurgical. Hydrometallurgical processes include the flotation and leaching process, whereas pyrometallurgical processes include smelting and refining process. The chemicals used in these processes are categorized as flotation reagents, leaching chemicals, smelting chemicals, and refining chemicals.

Potassium Amyl Xanthate (PAX) packed in both wooden containers and drums, ready for export.

Flotation Reagents

The flotation process is a widely used hydrometallurgical method to separate gold from gold containing ores. Flotation reagents are chemicals that help in the attachment of air bubbles to the minerals and bringing them up at the surface. When on the surface, these reagents further help to form a froth layer which makes it easier to remove the minerals. Flotation reagents can be classified into three main categories i.e., collectors, frothers, and modifiers.

 

1. Collectors

Collectors are chemicals that selectively attach to the surface of the mineral (gold) making the mineral hydrophobic. Hydrophobicity is necessary for air bubble attachment. Collectors are used to modify the surface properties of gold in flotation process. They either bond on the mineral surface or be held on it by absorption. This helps the air bubbles to attach to the mineral.

Most popular collectors are:

Xanthates

Xanthates are water-soluble salts that are very important in mining for the extraction of ores. These salts are used in the mineral processing processes as flotation reagents. These salts differ in their selectivity and strength in recovering the mineral.

Xanthates include:

 

• Potassium Amyl Xanthate (PAX): PAX is a strong and non-selective collector.
• Sodium Ethyl Xanthate (SEX): SEX is a highly selective weak collector.
• Sodium Isobutyl Xanthate (SIBX): SIBX is a generally good collector.
• Sodium Isopropyl Xanthate (SIPX): SIPX is a selective collector having a higher recovery rate than SEX.

Packaged Sodium Isobutyl Xanthate (SIBX).

 

2. Dithiophosphates

Dithiophosphates are phosphorous oxoanions. They are water-soluble salts that have properties that affect selectivity and froth character. They are more effective in alkaline flotation processes. Dithiophosphates are more selective than the xanthate salts.

Dithiophosphates include:

 

• Ammonium Dibutyl Dithiophosphate: Ammonium Dibutyl Dithiophosphate is used in the copper-lead sulfide flotation because it has the potential to improve selectivity.
• Sodium Dibutyl Dithiophosphate: Sodium Dibutyl Dithiophosphateis used in the flotation of nickel and copper sulfides.
• Sodium Diisobutyl Dithiophosphate: Sodium Diisobutyl Dithiophosphate is used in copper, nickel, and zinc flotations and gives high yields of precious metals.

Other collectors include Dithiophosphate 25, Dithiophosphate 25S 95%, Amino-Dithiophosphate, Ethyl Thiocarbamate, Isopropyl Ethyl Thionocarbamate, Collector BLK-301 and Collector T-610.

 

3. Frothers

Frothers are chemicals that perform key functions in the flotation process. They are responsible for reducing the surface tension for the formation of froth. They help stabilize bubble size and in the hydrophobic particle attachment to air bubbles. These compounds also help stabilize the foams. Frothers include:

 

• Pine Oil: Pine Oil is a natural oil frother and is quite extensively used worldwide.
• Methyl Isobutyl Carbinol: Methyl Isobutyl Carbinol is a widely known weak frother. It produces brittle froth.

Other available frothers at Camachem include Pine Oil replacement high compound alcohol for non-ferrous mines (CC-321) and CC-903 for sulfide ores.

 

4. Modifiers

Modifiers are compounds that are added to optimise the separation process. Adding these reagents results in a modified and controlled flotation process.

Modifiers include:

 

• Sodium Cyanide: Sodium Cyanide can be used both as an activator as well as a depressant. It is quite strong as a depressant of Iron and Zinc sulfides. As an activator, it improves flotation.

Sodium Cyanide briquettes packaged in drums before export.

• Caustic Soda: Caustic Soda is a pH modifier which is used to raise the pH.
• Soda Ash: Soda Ash is also a pH modifier which is used to raise the pH.
• Copper Sulfate Pentahydrate: Copper Sulfate Pentahydrate is used as an activator in Zinc Sulfide and Iron Sulfide minerals.
• Sodium Metabisulfite: SMBS is used as a depressant in Zinc Sulfide and Iron Sulfide minerals.
• Hydrated Lime: Hydrated Lime is used as a depressant for pyrite.
• Lead Nitrate: Lead Nitrate is used as an activator of antimony sulfide and reactivator of copper sulfide.

Other modifiers include isopropyl alcohol and oxalic acid.

Leaching Chemicals

Leaching is a gold extraction process in which the ore is treated with certain chemicals which help to convert the precious metals into soluble salts while impurities remain insoluble. It is gold extraction method from low-grade ore by converting gold to a water-soluble complex.

Leaching chemicals include:

• Sodium Cyanide: It is extensively used in cyanide leaching for the extraction of gold.
• Activated Carbon: Activated Carbon helps in the adsorption of gold-cyanide solution.
• Caustic Soda: It is responsible for the elution stripping of adsorbed gold on activated carbon.

Preparation of lead nitrate for our mining client.

• Lead Nitrate: It acts as an accelerator in gold cyanidation.
• Sodium Bisulfite: Sodium Bisulfite detoxifies cyanide in gold extraction.
• Sodium Metabisulfite: It also detoxifies cyanide in gold extraction.

The solution then becomes ready for electrowinning. In this process, a strong electric current is made to pass through the solution from the positive and negative terminals of the container. This causes gold to collect on the negative side. In this way, gold is recovered from the chemicals.

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The solution then becomes ready for electrowinning. In this process, a strong electric current is made to pass through the solution from the positive and negative terminals of the container. This causes gold to collect on the negative side. In this way, gold is recovered from the chemicals.

Packaging and loading of activated carbon. Activated carbon is a crucial chemical during gold cyanidation. It is available in different sizes and CTC levels depending on clients’ requirements at their mine.

Smelting Chemicals

Smelting is a process in which the negative terminals of the electrowinning cells are melted in a furnace at a high temperature. Then a chemical mixture called flux, which may contain dense soda ash along with other chemicals, is added to the molten material to separate gold from the terminal metal. The molten gold is then poured into molds to transform the liquid into solid gold bars. These are low-purity bars that are sent to refineries for processing.

Refining Chemicals

Refineries remove impurities that remain after smelting. There are various refining processes like Cupellation, chlorination, and Wohlwill process etc. After being refined by either of these processes the refined gold is then sent to be used in whichever way it is needed.

Packaging and Shipping of Chemicals

All the chemicals are packaged and shipped with care. Depending upon the chemicals ordered, they are typically packaged in:

• Sealed wooden boxes.
• Sealed wooden drums.
• Sealed steel drums
• Woven bags

Camachem loading SMBS for gold mining client.

Chemical Samples

We, at Camachem are always ready to facilitate our clients with samples so that they can test the chemicals and their compatibility with the ore.

Gold Mining Chemicals at Camachem

We, at At Camachem we supply various mineral processing chemicals suitable for the mining sector especially gold processing. We have a variety of mining chemicals including flotation reagents, leaching chemicals and other processing chemicals for minerals and ores such as copper, lead, zinc, silver, gold, and nickel. We are ready to serve and provide you with the right gold processing chemicals. Contact us ([email protected]) for FREE consultation and pricing.