Gold Ore Processing Technology
Over 98 kinds of gold ores or gold-contained mineral ores has been discovered up till now, among which, only 47 are the most common ones, and only 10 kinds can be directly used for industry. China has about 38 kinds of gold-contained mineral ores, and most ores are of low grade.
Gold ore application
Gold is output products for gold investment, investors are well known that it is loved by consumers around the world. Under the background of the collective buying holdings of gold reserves, and the growing global gold consumption and investment demand, which provides sales guarantee for gold mine output products. Whether to invest in gold jewelry, or gold output products, both have huge market potential.
Gold ore processing technique
Now the gold beneficiation's main technique is: ores are crushed to small size by crushers, grinded by ball mill, and then separated by gravity or flotation ways to get gold concentrate and tailings. Or by chemical process, then go through smelting to get final product-pure gold.
Gravity separation is widely used in the rock gold mine, more as an auxiliary craft. Recovered coarse gold in the grinding circuit, which is to create favorable conditions for the flotation and cyanidation process, can improve mineral indicators and overall recovery of gold. Therefore gravity separation plays a positive role to increase yields and lower costs.
It is understood that rock gold mine most adopt flotation for beneficiation, there are usually two kinds of processes: differential flotation and bulk flotation. However, as same as others, the flotation method is not as a panacea. It is impossible and valid for all the gold-bearing ores beneficiation. The nature of the ore is main consideration when doing gold beneficiation, it also need a wide range of demonstration and testing in the choice of craft process.
Cyanidation processes may include the following operations:
- 1. Agitated tank leaching
- 2. Heap leaching
- 3. Carbon adsorption recovery
- 4. Zinc precipitation recovery.
As for carbon adsorption recovery, it mainly include three alternatives, carbon-In-Pulp(CIP),carbon-In-Leach (CIL),carbon-In-Column (CIC).
Refractory ore processing
Refractory ore processing methods almost always serve only one purpose, to treat ores that will not liberate their values by conventional cyanide leaching. The refractory ore treatment process is then followed by a conventional cyanidation step. Refractory ore processing methods include:
- 1. Bioleaching
- 2. Autoclaving (pressure oxidation)
- 3. Roasting
- 4. Clorination
- 5. Pre-oxidation
- 6. Lime/caustic pretreatment
Today, cyanide leaching is the method of choice for the recovery of most of the world’s gold production. There are however, many other chemical leaching processes that have been sporadically or historically used. In most instances, cyanide leaching will provide a more technologically effective and cost efficient method. Alternative lixiviants include:
- 1. Bromides (Acid and Alkaline)
- 2. Chlorides
- 3. Thiourrea
- 4. Thiosulfate
Amalgamation is one of the oldest processes available. It relies upon the contact of ore with mercury to form a gold-mercury amalgam. This process is strongly out of favor with the major mining companies, due to the extremely toxic nature of mercury and the processes inferior performance when compared to the available alternatives. The process is still used extensively by artesian mines in third world countries and at small “mom and pop” mines, due to its simplicity.
Gold concentrate quality standard and Industrial index
Gold, due to its number of rare and unique physical and chemical properties, since ancient times it has been regarded as hardware first. As the "King of the metal", gold concentrate quality standard and industrial index are as follows:
Gold concentrate quality standard
|Grade\Quality||Au(10-6)||As (%)||Grade||Au(10-6)||As (%)||H2O (%)|
|I||≥180||≦0.3||VII||≥80||≦0.35||General ≤12 Wintertime≤8|
|Mo and S in Gold concentrate are valuation element|
|Cu (%)||Pb (%)||Zn %)|
|Copper-containing gold concentrate||≥1.0||≦3||≦3||Au、Ag、Cu、S Valuation|
|Aluminum-containing gold concentrate||≦1.5||≥10||Au、Ag、Pb Valuation|
Industrial index for rock gold mine DZ/T0208-2002)
|Type||Cut-off grade (10-6)||Minimum Industrial Grade(10-6)||The average grade of ore deposit (10-6)||Minimum mining thickness(m)||Rock excluding thickness(m)||Excluding non-ore block thickness|
|Primary ore||1~2||2.5~4.5||4.5~5.5||Steep 0.8 Decantation 1.5||Underground mining 2 Open-pit mining 4||Corresponding Engineering 10~15 Non 20~30|
|Heap leaching chlorine onoxide||0.5~1||1~1.5|