Vietnam gold mining

Vietnam gold mining

A nation with abundant and diverse mineral resources, which serve as a valuable resource for the nation

A LMOST 5,000 deposits and ore occurrences, with 70 different kinds of minerals, have been discovered in Vietnam. The country’s mining industry, although still developing, has made an important contribution to the country’s socio-economic development, and to the speeding up the industrialisation and modernisation of the nation. Vietnam’s geological survey has completed 1:500,000 and 1:200,000 scale geological maps throughout the mainland territory, and about 25% of the area has been mapped at 1:50,000 scale. In addition, a survey of the oil and gas fields, tin and gold, titanium, rare-earth placers in the continental shelf and offshore areas has also been carried out.

ENERGY MINERALS

Oil and gas was first discovered in Vietnam in the 1970s but it is only after 1984 that the oil and gas industry has made firm steps forwards. The deposits are concentrated in the sedimentary basins of Song Hong, Cuu Long, Nam Con Son, Malay, Tho Chu, Phu Khanh, Tu Chinh, Vung May and Truong Sa. Some 37 businesses co-operation contracts have been signed between PetroVietam and foreign companies for exploration and production of oil and gas, with a total area of about 250,000km2 , accounting for 50% of the total area of the continental shelf of Vietnam. Oil reserves are estimated at 2,300Mt, of which 615-957Mt is proved reserve. The gas reserve is estimated at about 1,300Bm3 , of which 600Bm3 is proven.

The coal deposits in Vietnam were formed in eight different periods: Early-Late Devonian, Early-Middle Carboniferous, Late Permian, Middle Triassic, Late Triassic, Early Jurassic, Neogene and Quaternary. The coals formed in Late Triassic and Neogene are of highest economic value. Coals with economic value are concentrated in Late Triassic formations, and mainly in the Quang Ninh coal basin (forming various coal fields such as Cam Pha, Duong Huy, Hon Gai, Uong Bi and Bao Dai), which accounts for 95 % of the country’s coal reserve; the Song Da coal basin in the north, and the Nong Son coal basin in the central region. The total estimated reserve of Late Triassic coal is 6,600Mt. Coal output reached 33.9Mt in 2005, of which Vinacomin produced 31Mt, with 18Mt for export.

IRON DEPOSITS

There are a reported 216 iron-ore deposit in Vietnam, mainly concentrated in the northern provinces (such as Yen Bai, Cao Bang, Thai Nguyen, Ha Giang and Ha Tinh). Total estimated iron-ore reserves are about 1,200Mt, with 13 deposits of over 1Mt and six explored in detail (Trai Cau, Tien Bo mines in Thai Nguyen province, Nguom Chang, Na Lung mines in Cao Bang province, Thach Khe deposit in Nghe Tinh province and Quy xadeposit in Lao Cai province). Iron ore is currently mined at Trai Cau, Tien Bo, Nguom Chang and Na Lung. The two biggest iron ore deposits (Thach Khe and Quy Xa) are available for new investment.

BAUXITE DISTRIBUTION

Deposits and ore occurrences of Vietnam are of very wide distribution, however they are relatively concentrated. By genesis, bauxite ores are of two main types; sedimentary (some metamorphosed) and lateritic weathering from basalt.

The deposits of sedimentary genesis are distributed in Cao Bang, Lang Son, Ha Giang, Hai Duong and Nghe An provinces. Of these, the deposits in Lang Son are of large reserve, high quality and industrial value. In Lang Son there are 36 deposits and ore occurrences, mainly of eluvial and deluvial type. In mineral composition, bauxite is composed mainly of diaspore (60-70%), boehmite (20-30%) and gybsite. The total reserve is estimated to be some hundred million tonnes. Bauxite deposits as products of weathering from basalt are concentrated mainly in Dak Lak, Lam Dong, Kon Tum and Quang Ngai. The total bauxite-bearing area is up to 20,000 km2 . The crude bauxite ore is usually of low quality. In mineral composition the bauxite consists mainly of gibbsite, goethite, kaolin and ilmenite. Bauxite deposits as weathering products from basalt have very large reserve, about 4,000Mt and prognostic reserve of 6,700Mt.

At present time, a significant number of foreign investors are interested in bauxite mining and the production of alumina in the Dak Nong area, with the capacity of each project being 1-2Mt/y alumina.

TIN MINERALISATION

Tin and tungsten mineralisation in Vietnam is related to granitic rocks of various tectonic cycles, including Precambrian, Mesozoic and Cenozoic. But only the deposits related with Mesozoic and Cenozoic cycles are of economic value. There are four main tin-bearing areas: Piaoac and Tam Dao in the north, Quy Hop in the central region and Da Trai in the south. The Piaoac area is 42km west of Cao Bang and about 340km north of Hanoi. It was determined to have a placer ore reserve of 23,000t SnO2 and 1,500t WO3. However, this reserve is now nearing exhaustion.

The Tam Dao area is 130km north of Hanoi and covers about 1,500 km2 , extending in a NW-SE direction. The total reserve is estimated to be 13,600t SnO2. Preliminary results show that the mineral potential of the Tam Dao area is promising, with significant levels of tin, tungsten and other elements (such as bismuth and beryllium).

Quy Hop is located in the west of Nghe Tinh province, 250km south of Hanoi. In geological setting, this area is part of the Phu Hoat uplift with sedimentary and metamorphic rocks aged Pre-Cambrian and Lower Paleozoic. This area has a total reserve of 36,000t cassiterite. The estimated total primary ore reserve of this area is 2,065t of tin. Da Trai is 30km northeast of Da Lat. The estimated mineral reserves of this area are given as 40,000t Sn and 200,000t WO3.

EXTENSIVE GOLD

Gold is one of minerals with the most extensive distribution area, having a wide range of geneses and diverse forms of deposits. So far, 140 dispersion haloes of various sizes have been delineated. They are mainly concentrated in the marginal part of Song Hien depression (Pac Lang, Na Pai deposits), along the Song Hong, Song Da and Song Ma deep-seated faults, or in the marginal part of Hoa Binh uplifted block (Kim Boi deposit) and Kontum uplifted block (Bong Mieu, Tra Nang and Suoi Ty deposits).

Based on their formation and occurrence characteristics, gold deposits are divided into three types. 1. Gold placer. Often closely related to river and stream sedimentary formation, the reserve varies from 200-400kg and the average content is 0.31- 2.95g/m3 . Up to now about 150 deposits and ore occurrences have been discovered. The estimated resource is 5,000kg and the predicted reserve is 11,000kg.

Primary gold is distributed mainly along mineralising formations, eg quartz-gold (Bo Cu mine in Thai Nguyen province), quartz-sulphide-gold (Pac Lang, Tra Mi and Bong Mieu), gold-silver (Na Pai and Xa Khia). The average grade in each mine varies from some few grammes per tonne to tens of grammes per tonne.

Associated gold is one of the country’s most important mineral resources. Up to now, gold associated with antimony, copper, tin, lead and zinc have been discovered in many places, but the most significant is gold found has been at the Sinh Quyen copper mine, which has an estimated reserve of nearly 35t and an average grade of 0.46-0.55g/t Au.

 

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