3.4.1.1 Reserves and Resources

By the end of 1997, 56 chromite ore districts had been identified with retained reserves of 9.002 million tons, of which 3.611 million tons belong to categories A+B+C. The reserves obtained in the detailed reconnaissance and exploration stages amount to over 97% of the total chromite reserves of the country.     

According to Prof. Li Tong from the Beijing University of Science and Technology, the total resources of chromite is estimated at 44 million tons.     

Statistics made by the USGS show that the world's total chromite reserves were 3.7 billion tons in 1998 with the reserve base of 7.5 billion tons. South Africa is the leading country with chromite reserves of 3 billion tons and the reserve base of 5.5 billion tons. Countries of secondary importance are Zimbabwe (reserves: 140 million tons; reserve base: 930 million tons), Kazakhstan (reserves: 320 million tons; reserve base: 320 million tons), and Russia (reserves: 4 million; reserve base: 460 million). Other major countries include Finland, India, Brazil, Turkey and Albania. Comparison between the reserves of categories A+B+C of China and the reserve bases of these countries shows that China is far behind them.     

The 56 explored chromite ore districts are distributed in 13 provinces, municipalities and autonomous regions, including Tibet, which has retained reserves of 2.481 million tons, amounting to 27.6% of the national total; Inner Mongolia with retained reserves of 1.744 million tons (19.4%); Xinjiang with retained reserves of 1.703 million tons (18.9%); and Gansu with retained reserves of 1.443 million tons (16.0%). Moreover, Beijing, Qinghai, Hebei, Jilin, Hubei, Shaanxi, Shanxi, Sichuan and Yunnan have retained reserves of 1.631 million tons in total, accounting for 18.1% of China's total (Table 3.4.1)

In terms of the six large administrative regions of China, the chromite deposits are largely distributed in Northwest China (3.699 million tons, 41.1%), North China (2.749 million tons, 30.5%), and Southwest China (2.493 million tons, 27.7%). Merely 0.7% of the total retained reserves of chromite are explored in Northeast China and South-Central China and even no chromite deposit has ever been discovered in East China so far (Fig.3.4.1).

3.4.1.2 Characteristics

Statistics show that about 11,443 basic and ultrabasic bodies have been discovered in China, with a total outcrop area of 11,147 km2, of which 8,635 are ultrabasic bodies, covering 4,516 km2; 464 basic-ultrabasic bodies, 328 km2; and 2,344 basic bodies, 6,303 km2. There are 28 chromite-bearing rockbodies among the above basic-ultrabasic and ultrabasic bodies. The characteristics of the chromite deposits in China are discussed below.

Table 3.4.1 Retained reserves of major chromite deposits in China(t)

1) Space-time distribution.The formation of the chromite-bearing basicultrabasic rocks in China spans the time interval from Precambrian to Tertiary, but the chromite-bearing basic-ultrabasic rocks of industrial value were formed primarily in the Hercynian and Alpine stages, whose retained reserves make up 54.9% and 27.7% respectively, and secondarily in the Precambrian and Caledonian with the retained reserves amounting to 11.5% and 5.9% respectively.

2) Simple metallogenesis.The known chromite deposits in China are mainly late magmatic ones. Geologically the deposits can be divided into two groups. Deposits of the first group occur in dunite-clinopyroxenite type rocks predominated by dunite. They are generally small deposits with lean ore. The Gaositai and Maojiachang deposits in Hebei, Fangmayu and Pingdingshan deposits in Beijing are some examples. The deposits of the second group occur mainly in dunite-harzburgite type magnesian rocks predominated by harzburgite in Paleozoic and younger geosynclinal areas. This is the major type of chromite deposits in China. They are generally medium and small in size, such as the Luobusa deposit in Tibet, the Sartokay deposit in Xinjiang and the Hegenshan deposit in Inner Mongolia. Some well-known large and superlarge stratiform deposits of early magmatic segregation have been discovered in the world, but such deposits have not been found in China so far.

3) Uneven distribution and small size.As was mentioned above, 82% of the retained reserves of chromite are distributed in such remote areas as Tibet, Xinjiang, Gansu and Inner Mongolia. Chromite resources have not been found in provinces, municipalities or autonomous regions in East China, South China or coastal areas. Even in chromite deposits distribution areas, none of the deposits has reserves over 5 million tons and there are only 4 medium-sized deposits, i.e. the Luobusa deposit in Tibet, Dadaoerji deposit in Gansu, Sartokay deposit in Xinjiang, and Hegenshan deposit in Inner Mongolia.     

In terms of reserves, lean ores and rich ores go fifty-fifty. Of the present retained reserves, lean ores constitute 55.5% (4.993 million tons) and rich ores 44.5% (4.009 million tons). Rich ores are distributed mainly in Tibet and Xinjiang, accounting for 61.9% and 21.2% of the total rich ores respectively. In terms of uses, 37.4% of the total retained reserves are suitable for metallurgy, 38.4% for chemical industry, and 24.2% for refractories.

4) High degree of development.Up to now 32 chromite ore districts have been explored and utilized, whose total retained reserves are 6.443 million tons, amounting to 71.6% of the national total. Among them nine mines were shut down and the rest 23 are located in Tibet, Xinjiang, Gansu, Qinghai and Inner Mongolia, with a production of 170,000 tons. Nine of them have been brought into the planned development, whose retained reserves are 1.295 million tons, occupying 14.4 of the total of China, e.g. No.25 and No.26 mines in the Sartokay district; 15 are difficult to utilize in the near future because they have only lean and small ores and their retained reserves are 1.264 million tons, amounting to 14.0% of the notional total.