Vietnam’s refractory vision to 2020

By
Published: Wednesday, 06 June 2012

Vietnam is a country rich in minerals, boasting significant reserves of barytes, bauxite, and clays. Dr Tran Kim Phuong argues the case for foreign investment in Vietnam’s refractory raw materials, outlining their strategic development through to 2020


Vietnam is aiming to develop its domestic
refractories industry to serve its burgeoning
aluminium and steel sectors
Gerdau Ameristeel


Vietnam hosts abundant mineral resources, including barytes, bauxite, and clays. In addition, the country has significant resources of industrial minerals suitable for use in the foundries and refractories markets, which are discussed below.

The results of geological investigation and exploration within Vietnam found many mineral resources suitable for use in the metallurgical industry. Some of these can be used directly in the process of steel production, while others are used to manufacture the refractories.

In order to meet the developmental requirement of Vietnam’s aluminium and steel industries in the coming years, the investment to strengthen the exploitation of refractory minerals and production of a refractory base is more pressing than ever.

In this article, we wish to deal with the main mineral resource groups discovered in recent times as well as the strategic aim of refractory industrial development in Vietnam out to 2020.

Silica refractory group

Mineral resources that have the chemical formula RO2 such as silica (SiO2) and zirconia (ZrO2), are used for manufacturing acid-based refractories that are consumed by acid slag furnaces. Bricks manufactured from quartzite come under this group and require large amounts, around 8.5 kg per tonne of steel.

Diatomite, a mineral essentially composed of the siliceous remains of marine phytoplankton (diatoms), is also used for this purpose (its melting point is 2,666oC).

Zirconium is very much preferred in the manufacture of crucibles, fire bricks and sparking plugs. The crucibles that contain zirconium can withstand a temperature of over 2,500oC.

Quartzite

Many quartzite deposits have been discovered in North Vietnam, of which the Don Vang in Phu Tho province is the best quality (97-98% SiO2) used for production of refractory bricks at Thai Nguyen Iron and Steel Co.’s plant since the 1960s.

The Xuan Hong quartzite in Ha Tinh province has a melting point of 1,730oC and is suitable for production of bricks and ceramics. Especially in Tinh Gai and Dong Son districts (Thanh Hoa province) there are some quartzite (sandstone) occurrences with 90-95% SiO2, occurring in the form of large boulders on the land surface, that may be mined and directly used.

Up to now, there have been 24 quartzite deposits evaluated with a total reserve of 272m tonnes. There are some large deposits such as the Lang Lai of 131.5m tonnes, the Don Vang at 31m tonnes and the Xuan Hong at 15m tonnes which will be important material sources, highlighted to supply the steel complexes being constructed in Ha Tinh and Lao Cai provinces.

Zircon

In Vietnam, 33 deposits of ilmenite and zircon have been identified with total reserves of 30.919m tonnes, of which zircon is 1.030m tonnes. Some coastal placers of high zirconium content are the Ky Khang, Ha Tinh province (65,500 tonnes) with zirconium content of 18-18.5 kg/m3; the Quang Ngan, Thua Thien - Hue province (48,700 tonnes) with zirconium content of 12.2-13. 44 kg m3; the Cat Khanh, Binh Dinh province (32,055 tonnes) and the Ham Tan, Binh Thuan province (442,200 tonnes) with zirconium content of 2.0-56.7 kg/m3.

The exploitation of zirconium ores is concentrated mainly in Ha Tinh, Thua Thien - Hue and Binh Dinh provinces, with production from 10-20,000 tpa.

Diatomite

Some state-ranked projects carried out in 1990s have clearly outlined the distribution and potential of diatomite deposits in the Phu Yen, Kon Tum and Lam Dong provinces in South Central and Highlands (Tay Nguyen) of Vietnam.

The diatomite deposits in Tuy An disctict, Phu Yen province (South Central) distribute in four areas, namely Hoa Loc, Tuy Duong, Trung Luong and Tra Rang with total reserve of about 90m tonnes, of which the Hoa Loc is the largest with a reserve of 61m.m3 (about 50m tonnes).

Mined ores are milled to a grain size of <0.2 mm and heated at a temperature range of 800-1,000oC. The resulting product has a chemical composition of 73.8% SiO2, 13.02% Al2O3, 1.10% Fe2O3, and 0.04% TiO2, and is used to manufacture products for heat insulation, light aggregates, hydraulic cement, and fire bricks; as well as filters, absorbents, rubber additives, soaps and insecticides etc.

Alumina refractory group

The alumina materials group consists of fire clay, fire kaolin and high alumina refractories. They are used for the manufacture of chamottes brick, which are stable for all acid and basic slags and are the most used materials in metallurgy.

Fire clays

In the Tuyen Quang and Hai Duong provinces, the fire clay deposits can be used to produce refractory bricks of A and B grade chamottes. The Tuyen Quang clay deposit in Tuyen Quang province, with a melting point at 1,690-1,730oC, has been mined since the 1930s by the French.

The Truc Thon in Hai Duong province, with a reserve of 9.4m tonnes, has been exploited for many years - supplying raw materials for the production of refractory bricks and ceramics. The three main clay types are: 1) fire clay soil, grading ³26% Al2O3; 2) white clay soil, grading ³17-26% Al2O3, with plasticity of 14-19 and whiteness of 45.5%; and 3) chamottes to make different refractory grades, including grade I (³30% Al2O3, ²3.5% Fe2O3, melting point of 1,650oC) and grade II (³28% Al2O3, ²4.0% Fe2O3) with moisture absorption for both grades at ²8%.

Fire kaolin

Along left side of the Red River, from Lao Cai to Son Tay (about 220 km), there are many kaolin deposits of good quality that could be used for the manufacture of high grade porcelain, electric porcelain, refractory materials and fillers. These have been prospected in detail and mined.

Kaolin in the Dinh Trung (Vinh Phuc province), with reserve of 1.2m tonnes, is the product of weathering from fine grained granite which exhibits a high degree of plasticity and is especially suitable for manufacture of chamottes brick.

The Tan Mai pyrophyllite-kaolin deposit in Quang Ninh province, discovered in 1977 consisting of many bodies formed by hydrothermal alteration of acidic eruptive rocks, has very important economic significance.

The quality of the kaolin is rather stable, has a high alumina content (averaging 38.5%), and has a low level of impurities present. This kaolin has a refractoriness of 1,770oC, equivalent to same kind of kaolin found in China and the Czech Republic, to completely satisfy the requirement for manufacture of the A grade chamottes brick. The deposit has a reserve of 45.14m tonnes; approximately 20% of Vietnam’s total kaolin reserves.

Pyrophyllite can be divided into three types, the best of these being of fine-grained and massive texture; soft, opalescent, greenish and bluish colour. The content of pyrophyllite mineral can reach 90%, with a chemical composition of 63.3-68% SiO2, 25.1-28.5% Al2O3, 0.1-0.9% Fe2O3, 0.4-0.9% TiO2 and a LOI of 4.8-7.3%. Test results showed that refractory bricks produced from the Tan Mai pyrophyllite had a quality equivalent to that of Japan, with applications in the metallurgical and chemical industries.

In the Central region, the A Luoi kaolin deposit located in the west side of Thua Thien - Hue province, consists of 19 ore bodies with total reserve of 5.2m tonnes. It has been mined and the site is home to a kaolin processing factory which is considered to be the best in Vietnam. After processing, two kaolin grades are produced - grade I (Al2O3 content of 32.03%) and grade II (21.15% Al2O3) with recovery being >71%.

In the Highland region (Tay Nguyen), the Ia Knop deposit in Dac Lac province is an important refractory material source. The kaolin’s chemical composition ranges 22.2-34.2% Al2O3, 0.24-0.35% Fe2O3, with a plastic index of 9-13 and a refractoriness of 1,700¡C. The reserve of this deposit is about 3m tonnes.

High alumina refractories

The silimanite group of alumino-silicate minerals, consisting of silimanite, andalusite, and kyanite (with dumortierite and mullite being similar in structure), are used in high-alumina refractories of over 1,800oC. Kyanite is usually finely ground and mixed with fire clays to increase the refractoriness of the brick. Kyanite, together with andalusite, may be used for making spark plugs for internal combustion engines.

In North Vietnam, kyanite has been found in Thanh Son district, Phu Tho province and in Quy Hop district, Nghe An province. The Thanh Son kyanite comprises (after gravity and magnetic beneficiation) 53.52% Al2O3, 40.65% SiO2, 2.23% Fe2O3, 1.12% CaO, and 0.20% MgO. The deposit has a reserve of 60,000 tonnes.

Material from this deposit was successfully tested in the manufacture of high-alumina refractory bricks from the Tan Mai kaolin (Quang Ninh province) mixed with Thanh Son kyanite.

In South Vietnam, the Hung Nhuong silimanite occurrences in Son Tinh district, Quang Ngai province lie in four bodies in association with graphite. The average content is 27-29% Al2O3, 1.03-3.38% Fe2O3, and with total reserves of 105,500 tonnes.

Alkaline refractories

The magnesia material group is used for making alkaline refractories, applied in the basic slag heating zone of kilns. The minerals have formula of RO, largely represented through magnesia (MgO) which is sourced primarily from magnesite ores.

Other alkaline bricks are manufactured from similar mineral resources such as dolomite, serpentine, chromite and so on. The demand for alkaline refractories in industrial sectors is not as large as other compositions, but the high refractoriness of 2,800oC makes these products irreplaceable in certain applications - such as the heating zone of cement rotary kilns and basic steel blast furnaces.

Magnesite

Magnesite ore was discovered recently in the Ban Phung, Son La province in 1995 and in the Kon Queng, Gia Lai province in 2005. Although the deposits do not have large reserves, they can meet the requirements of alkaline refractories and aid the development of Vietnam’s steel industry.

Ban Phung deposit:
Preliminary exploration of a 4 km2 area has highlighted a probable reserve of more than 1.2m tonnes magnesite. The ore belongs to the metasomatic-genetic type from ultramafic rocks, with the main minerals being magnesite-quartz accompanied by magnesite-talc.

From processed ores, the refractory plant of Thai Nguyen Iron and Steel Co. has successfully manufactured magnesia bricks grading 89.87% MgO, 3.51% CaO, 1.65% SiO2, 0.5% Al2O3, and 1.0% Fe2O3.

By using suitable technology, Ban Phung magnesite can be used to manufacture magnesia bricks of a quality equivalent to imported Russian bricks (GOST - 468a/63).

Kon Queng deposit:
The Kon Queng magnesite deposit was discovered in 2005 in Kon Chro district, Gia Lai province (Highlands). The total reserve is estimated at 14.782m tonnes, of which proven reserves are 6.1m tonnes.

The ore belongs to hydrothermal-metasomatic type from dolomite, seen as the most promising magnesite type in the world. An average content of the ores is 42.12-43.04% MgO, 0.95-1.90% CaO, 1.74-2.74% SiO2, 3.8% Fe2O3, and 0.01% TiO2.

Good quality ore can be beneficiated and used for refractory materials, and also may be used for making monolithics for linings in steel and cement furnaces.

Dolomite

Dolomite deposits occur in many locations in north-east, north-west Bac Bo, Central Vietnam (Trung Bo) and in some areas of the Highlands (Tay Nguyen). In Vietnam, 17 deposits have been evaluated with total reserves more than 1.8bn tonnes, of which the biggest is the Ban Chanh in Hoa Binh province with 1.6bn tonnes.

The two main deposits being exploited by Thai Nguyen Iron and Steel Co. are Ngoc Long, Thanh Hoa province and La Giang, Thai Nguyen province, with current production at about 50,000 tpa. The refractoriness of Ngoc Long dolomite is 1,780oC and La Giang is 1,790oC.

During 1970-1980, when Vietnam was not exploiting magnesia raw materials, the Gia Sang steel laminating plant of Thai Nguyen Steel, successfully developed alkaline refractories based on dolomite and coke oil. These products were used in the lining of two furnaces at the plant and for welding and repairing the wall of another furnace.

Serpentine

Five serpentine deposits that have been explored are Bai Ang (Thanh Hoa province), Xom Quyt (Hanoi), Suoi Can (Son La province), Thuong Hoa (Yen Bai province) in North Vietnam and Lang Hoi (Quang Nam province) in South Vietnam with total reserves of 41.3m tonnes, but up to now only the Bai Ang has been mined.

The chemical composition of Bai Ang serpentine is 32.42-35.54% MgO, 38.96-40.82% SiO2, 1.25-1.37% Al2O3, 7.41-7.46% Fe2O3, 0.4-1.07% Ni.

The Bai Ang serpentine deposit has a reserve of 15m tonnes and 25-30,000 tpa is exploited for thermo-phosphate fertiliser plants. Test production of periclase-forsterite brick from Bai Ang serpentine has also obtained very good results.

Chromite

In Vietnam, chromite was first found in Co Dinh, Thanh Hoa province in 1927 and exploitation started in 1930 by the French. Rather than being in lump form, the ore occurs in sandy, granular (placer) grades. The majority of the chromite grain size falls between 0.07-0.7mm, which is very favourable for refractory production.

Test results have shown that the chrome-magnesia bricks manufactured from the Co Dinh chromite ore always meet quality standards, and correspond to some brick grades of Austria, the Czech Republic and Russia.

The Co Dinh chromite deposit has a total reserve of 21.5m tonnes, accompanied by 3m tonnes of nickel (Ni) and 281,000 tonnes of cobalt (Co). Vietnam stands in the top ten chromite resources of the world.

Vietnam’s refractory industry to 2020

In the 1960-70s, the refractory plant of Thai Nguyen Steel used Don Vang (Phu Tho province) quartzites for manufacturing bricks (SiO2 ³93%) for repairing the coke refining furnaces, with output totaling about 3,000 tpa.

In 1980-90s, the chamottes brick and mortar occupied up to 80% of Vietnam’s refractory production; mainly from the Cau Duong plant (Hanoi), the Tam Tang plant (Bac Giang province) and the refractory plant of Thai Nguyen Steel.

Now, in Vietnam, there are three foundations of refractory production: the Thai Nguyen refractory joint stock company, Cau Duong refractory company and Tu Son alkaline refractory factory.

The Thai Nguyen refractory joint stock company is the leading producer with an output of 60-65,000 tpa fire brick and mortar. The products of A and B grade chamottes brick, high-alumina brick with Al2O3 content from 45-80% and magnesia-carbon brick supply many sectors such as metallurgy, cement, chemicals, ceramics and glass etc. The products also have been exported to some Asian countries such as South Korea, Taiwan, Japan and Indonesia.

The Cau Duong refractory joint stock company in Dong Anh district, Hanoi, was established in 1959 and has a capacity of 20,500 tpa of A and B grade chamottes brick; 6,000 tpa of high-alumina brick with Al2O3 content from 48-85% and 2,500 tpa of heat insulation spongy brick, fireproof mortar and chamottes grids. The company’s products have been approved by the Vietnam standard TCVN 4710 - 98 and European standards.

The Tu Son alkaline refractory plant in Bac Ninh province, built in 2001, produces the magnesia-spinel and magnesia-carbon bricks, tamping material, stone powder and fireproof mortar attaining international standards (alkaline refractory material).

The plant output reached 7,250 tonnes in 2007, of which the brick used for cement rotary kilns was 6,376 tonnes, 378 tonnes for steel blast furnaces, and 495 tonnes for tamping material.

The total output of Vietnamese refractory materials in recent years has ranged in 95-100,000 tpa, consisting of three main products: chamottes, high-alumina, and alkaline bricks.

The development of Vietnam’s iron and steel industry to 2020 and vision to 2025 will see the exploitation of the iron deposits at Tien Bo (Thai Nguyen province) with a total reserve of 24.2m tonnes. In addition, iron deposits will be developed at Quy Xa (Lao Cai province) with 116.2m tonnes of reserves, and Thach Khe (Ha Tinh province) with a total reserve of 544m tonnes and an average content of 58.04% Fe (this project envisages an initial production of 5m tpa iron ore).

Iron ore from Thach Khe deposit will be supplied for the Ha Tinh Steel Complex with a capacity of 4.5m tpa.

The development aim of Vietnam’s steel industry to 2025 is as following:

- To 2020: production attaining 8-9m tonnes pig iron;

- To 2025: production reaching 10-12m tonnes pig iron.

To meet the demand for refractories within metallurgical sector and others, the target to 2020 is as follows: chamottes production growing from 560,000 to 630,000 tpa; silica-based bricks production growing from 68,000 to 76,500 tpa; and alkaline refractories production climbing from 148,000 to 156,500 tpa.

The target aims for total refractories production to grow from 776,000 to 854,000 tpa.

In order to guarantee sufficient supplies of refractories to Vietnam’s steel complexes in Ha Tinh province and Lao Cai province, and expanded to the Thai Nguyen Steel complex in Thai Nguyen province, we request foreign investors to strengthen the domestic refractories industry; focusing mainly in the alumina and alkaline groups, the raw materials of which exist abundantly in Vietnam.

The deposits that show most promise for development include the Tan Mai pyrophyllite-kaolin in Quang Ninh province, the Son Man kaolin in Lao Cai province, the Thuong Hoa serpentine in Yen Bai, the Ban Chanh dolomite in Hoa Binh province, the Co Dinh chromite in Thanh Hoa, the Xuan Hong quartzite in Ha Tinh province, and the Kon Queng magnesite in Gia Lai province.

The mineral resources that can be used for refractories production are abundant in Vietnam, and more refractory materials will be needed over the coming years. With a new, amended mineral law that came into effect on 1 July 2011, more favourable conditions exist for foreign investors.





Contributor:
Dr Tran Kim Phuong, Vietnam Institute of Geosciences and Mineral resources (VIGMR), Thanh Xuan, Hanoi, Vietnam.
phuongicf@gmail.com

References:

Dang Van Can et al. 1995. Geological, mineral and geochemical characteristics of magnesite ore zone in Ma river higher section area. In Geology and Mineral resources, vol 4, pp.195-206, Vietnam Institute of Geosciences and Mineral resource, Hanoi.

Le Thac Xinh, Le Dinh Huu, Tran Van Tri. 1983. Mineral resources of Vietnam’s north region, vol 5, Non-metal deposits, pp.250, General Department of Geology, Hanoi.

Ngo Van Minh. 2005. Geological features and distributive rule of magnesite ores of Kon Queng area, Kon Chro district, Gia Lai province. Proceedings of scientific conference on the occasion of 60 years of Vietnam Geology, Geological and Minerals Department of Vietnam, Hanoi.

Tran Xuan Toan, Nguyen Ngoc Phien. 1977. Discovery of second quartzite in Tan Mai, Journal of Geology, vol 130, pp.26-28, General Department of Geology, Hanoi.