Sun rises on Vietnam’s barytes

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Published: Friday, 27 May 2011

Dr Tran Kim Phuong outlines Vietnam’s principal barytes resources and key end markets, such as oilfield minerals, and discusses the country’s exploration plans to 2025

 
 
Vietnam has identified and assessed over 20 deposits and occurrences of barytes deposits with total reserves of 6.213m. tonnes. On the basis of distribution, mineralisation type and ore quality of the deposits, it is possible divide the three main prospective regions in Vietnam as north-east Bac Bo, north Trung Bo and north-west Bac Bo (see map).

The country’s barytes deposits occur mainly as three types: mono-mineralic barytes, barytes with sulphur, and barytes with rare earth minerals and fluorspar, of which the first type are widespread, accounting for about 80% of the prospective areas.

North-east Bac Bo region

In the provinces of Tuyen Quang, Thai Nguyen, Cao Bang, Lang Son and Bac Giang, deposits and occurrences of barytes have been discovered, with some deposits in Tuyen Quang being exploited at an industrial scale.

Elsewhere, provinces such as Phu Tho and Lang Son have also seen small-scale barytes mining. The north-east Bac Bo region - mainly the provinces of the northern mountainous areas - was evaluated as Vietnam’s best prospective region for barytes mineral resources.

The Ao Sen deposit located in Son Duong district, Tuyen Quang province, with a reserve of 393,580 tonnes, has been developed with a mining output of about 80,000 tpa consumed by the oilfield minerals and chemicals industries.

Here, the barytes ore is mainly concentrated in quartzite and sericite shale from the Early Palaeozoic, and is of medium quality. The BaSO4 content varies from 48-65%, but if processed through the 200 mesh size the BaSO4 content is 80-89%. In quality, the barytes of Ao Sen meets all requirements according to the standards set out by the American Petroleum Institute (API - see Table 1).

The analysis of the heavy metals, carried out in the Baroid Laboratory (United Nations), showed levels as: arsenic (As) 0.52 mg/kg, cadmium (Cd) 0.01mg/kg, lead (Pb) 400 mg/kg, mercury (Hg) 0.13 mg/kg and zinc (Zn) 0.01 mg/kg (min).

 Key barytes deposits in Vietnam
 
The content of Cd (0.01mg/kg) and Hg (0.13 mg/kg) is in permissible limits (towards Cd as 3 mg/kg), and towards Hg as 1 mg/kg),thus consequently the use of the Ao Sen barytes in drilling mud has no harmful effect on the marine environment, or to workers mining and processing material at the operation.


The deposit can be exploited by open pit methods down to 50 metres with the coefficient of ore-earth loading averaging 0.93 m3/ tonnes ore.

Out of prospected deposits in the north-east Bac Bo region (see Table 4), in the period between 2010 and 2015 Vietnam’s geological institute will strengthen the exploration and prospecting work for newly discovered deposits of large-scale reserves and high quality ore in Cao Bang province, such as: Po Tau, Na Ke, Che Pen, Ban Vai, and Ban Ram, with reserves attained anticipated to reach 800,000 tonnes of B + C1 (proven and probable), equivalent to 111 + 121 according to current the reserve resource ranking system.

North Trung Bo region

In the Thanh Hoa and Nghe An provinces, belonging to the North Central region, there is a barytes mineralisation zone of about 60km in length and 15km in width, stretching from the west side of Thanh Hoa to the coastal areas of Nghe An, arranged in the North Truong Son mineralisation zone.

Barytes bodies are distributed through the zone in north/south and north-west/south-east orientations, crossing through volcanic sediments of Middle Triassic age. Eleven deposits and occurrences of barytes have been investigated and prospected preliminarily, of which five deposits in the south zone belong to the mono-mineralic (quartz-barytes) type - these being the Ky Chung, Ru Tram and Ru Quanh (Son Thanh deposit), Dien Tho and Ru Bin deposits.

Deposits in the central part of the zone belong to the sulphur-barytes (galena-quartz-barytes) type - the Dien Lam, Nghia Lam and Bao Tre - while three more deposits in the north of the zone belonging to the sulphur-polymetallic barytes group (containing Ba, Si, Pb, Zn and Hg), these are the Bao Khe, Xom Dang and Dong San deposits.

The north Trung Bo region also has large barytes prospects, but compared with the north-east Bac Bo region the ore quality is lower and requires more processing - many of the deposits belong to the sulphur mineralisation group.

The Son Thanh deposit (Yen Thanh district, Nghe An province) has been evaluated as the most prospective of the north Trung Bo barytes resources. The Son Thanh barytes ore has a densely massive structure in hydrothermal veins of quartz and barytes, in addition to other minerals such as goethite and chalcopyrite.

Pyrites is disseminated in barytes crystals or barytes is surrounded by iron hydroxide. The content in crude ore consists of: BaSO4 at 50-53%; Fe2O3 at 2.98% and SiO2 at 39.70%. Probable reserves are listed as 287,401 tonnes, corresponding to 156,991 tonnes of barytes concentrate.

Ore processing trials have been carried out on the Son Thanh barytes ore after flotation and gravimetric flotation, giving the following results:

  • a) Flotation: Son Thanh barytes ore is relatively easy to process via flotation by fat acid assemblage in an alkaline environment
  • b) Gravimetric flotation: Use of processing on washing out table. Crude ore was treated to a size of 1.6mm and separated after fractions of: 1-1.6; 0.63-1; 0.135-0.63; 0.063-0.315 and 0.063 mm.
 
 The late Bob Boyle, of Global Baroid Fluid Services, with barytes workers in Vietnam (see IM October 2009, p.27). The Barytes Association
As the Son Thanh barytes ore can be easily processed by flotation (washing out), it is possible to gather a concentrate of more than 90% BaSO4 content; but the ratio of real recovery was 43%, with intermediary ore at 42%, and BaSO4-bearing discarded ore high at 28.5%.

To obtain a concentrate of more than 90% BaSO4 content, it is possible use the two methods of flotation and gravimetric flotation together. Flotation is easy to use because of the simple processing flowsheet, and the concentrate attained has a high BaSO4 content (real recovery of 95%).

Besides the favourable exploitation setting - such as mineral bodies distributed in low hills and plains - Son Thanh also has favourable infrastructure for mining, such as roads, communication systems, and manpower.

North-west Bac Bo region

In the north-west region, deposits of barytes associated with rare earths have been found. Six deposits were discovered, of which only the deposits in Nam Xe and Dong Pao, Lai Chau province, have large reserves.

Here, the mineral composition is very complicated, consisting of bastnaesite, magnetite, uranopyrochylorite, pyrites, galena, apatite, fluorite and barytes, of which barytes usually accounts for 30%. Although there are large reserves, the barytes resource has usually been considered as an auxiliary product - secondary to the exploitation and processing of rare earths ore.

At the Dong Pao deposit (Phong Tho district, Lai Chau) the deposit consists of more than 60 ore veins of different sizes, in which there are eight main veins totalling 400-1,000 metres in length and more than 100 metres wide. Besides these, there are other major veins more than 200 metres long and 30 metres wide, in addition to a number of smaller veins and nests of ore.

 Global barytes production and consumption (8.5m. tpa)
 


Ore from the Dong Pao deposit belongs to fluoro-carbonate group, containing bastnaesite, fluorite and barytes minerals, of which barytes and fluorite are the main composition. It is possible to separate the area into three ore types:

  • Barytes ore (common): has barytes content from 30-50%, in some places up to 80%, usually found as distinct veins;
  • Fluorite-barytes ore, of which barytes comprises 10-60%, and fluorite comprises 5-70%;
  • Fluorite with associated barytes, of which fluorite comprises 90-95%.
 Table 1: Estimation of Ao Sen barytes after API quality standard
 
 Table 2: Flotation result of Son Thanh barytes ore 
 
  Table 3: Gravimetric flotation result of Son Thanh barytes ore
 
The deposit has large-scale probable reserves - 2.9m. tonnes of barytes and 1m. tonnes of fluorite - and is the largest barytes-rare earth-fluorite deposit in Vietnam.

Elsewhere, in the north-west Bac Bo region along the Song Da river, barytes ore was recently discovered in the Hoa Binh province. Barytes deposits also occur in the south-west Mun mountain of Luong Son district, 70 km west of Hanoi.

Barytes ores belonging to barytes sulphide formation include two types of mineralisation: a) barytes-sulphite, and b) barytes-quartz-sulphide. The ores are white, grey-white, pinkish white, and sometimes brownish in colour, with plate shape texture and compacted mass structure.

The BaSO4 content ranges from 90-95%, sometimes reaching 98% (ore body no. 1, average thickness of 4 metres), with Fe2O3 content ranging 0.2-1.5%, BaCO3 content at 2-2.5% and other elements in low amounts including Be, Fe, Ti, Cu, Pb, Sr, Mg, Al and Mn.

The specific gravity of barytes ore is more than 4.0 g/cm3 - usually 4.2-4.4 g/cm3 - which is ideal for use in the oilfield minerals market. Barytes ore in Hoa Binh province is distributed over a wide scale and exploitation conditions are rather favourable - the deposit is prospective.

Barytes exploration plan to 2025 

 Barytes end markets (8.5m. tonnes)
 
At present, the exploitation and production of barytes concentrate totals about 120,000 tpa, mainly for the oil drilling and chemicals industries. Approximately 8,000 tonnes have been supplied to the domestic market for manufacturing drilling mud in south shelf region.


A large amount of barytes (over 100,000 tonnes) is exported to many regions including Asia (Malaysia, Thailand), the Middle East, and South America (Mexico, Venezuela).




A plan for the exploitation and processing of barytes in Vietnam has been established, with the following targets - 2011-2015:

  • Investment for enlargement of the Bac Giang barytes production enterprise; exploitation of the Lang Cao deposit in Bac Giang province with production of 10,000 tpa;
  • Construction of a barytes processing plant in Cao Bang province with a capacity of 50,000 tpa, with supply sourced from Che Pen, Na Ke, Ban Vai - Ban Ran deposits (Cao Bang province);
  • Construction, improvement and enlargement of the Bao Tre (Thanh Hoa province) and Son Thanh (Nghe An) deposits, raising the capacity of each mine from 1,500 to 2,500 tpa;
  • Construction investment in the Dong Pao and Na Cua (Lai Chau province) barytes processing plants, where total capacity of barytes concentrate is about 41,500 to 42,000 tpa, in addition to a general project for the exploitation of Lai Chau’s rare earth-barytes-fluorite deposits.

Period from 2016 to 2025:

  • Increasing extraction with production reaching 300,000-350,000 tpa of barytes ores;
  • Investment in Lai Chau’s high value barytes processing, increasing capacity from 5,000 to 10,000 tpa.
Table 4: Vietnam’s barytes ore reserve to 2010 
 
 * Ranking system of reserve resource has been in application since 2006

Conclusions

Up to now over 20 deposits and occurrences of barytes ores have been found in Vietnam, with total reserves of 6.213m. tonnes. Although more exploration work will need to be undertaken on the deposits already highlighted, it is clear that Vietnam has a large potential resource of barytes ore.

Looking at distribution, type of mineralisation and ore quality in deposits, it is possible to divide three prospective regions - of which the north-east region of Bac Bo, chiefly in Tuyen Quang and Cao Bang provinces, is the most prospective.

The quality of Vietnam’s barytes meets the requirements of domestic markets and has
been exported to many countries in the world. Vietnam’s barytes products satisfy the API standards for drilling mud in the oil and gas industry. In addition, the content of heavy metals such as Cd and Hg is very low, and poses no harm to human health and the environment. Although only some deposits have been put into production, their economic value is great.

Currently, barytes produced in Vietnam is chiefly used for drilling muds. To increase the economic worth of the deposits, foreign investments need to investigate other key markets for the country’s production. Hence, investments need to focus on establishing
the scale of reserves and research into processing technologies to enrich and enhance the ore.Contributor: Dr Tran Kim Phuong, Vietnam Institute of Geology and Mineral Resources, Thanh Xuan, Ha Noi, Vietnam.

References
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Nguyen Van Quy. 1997. The potential of barytes ore in Vietnam. Journal of Geological Economy and Mineral Raw Material, 4, p. 22-25, Ha Noi.

Pham Minh Nam. 2000. Characteristics of geology and barytes mineralization in Yen Quang commune, Luong Son district, Hoa Binh province. Proceedings of scientific works, 31, Septme University of Mining - Geology, Ha Noi.

Phung Duc Do & Nguyen Thi Phuong. 1987. Processing research of the Son Thanh (Nghe - Tinh) barytes ore. Journal of Chemical Industry, 85, Ha Noi.

Tran Xuan Dzuc & Nguyen Van Tung. 1986. Mineralization of barytes in the North Truong Son region. Proceedings 1st Conference on geology of Indochina, Ho Chi Minh City, Geological Department of Vietnam, Ha Noi.

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