4.12.2.1Present State of Production   

According to the Mineral Commodity Summaries in 1999, in 1997 the world's annual production of natural diamonds was 57.70 million carats. The countries that ranked the first five places in the world's production were Australia, Congo (Kinshasa), Russia, South Africa and Botswana in succession. In 1997 China's annual natural diamond production was 120,400 carats.

Diamond mining in China is relatively weak and develops slowly in recent years. The diamond mines are grouped into primary diamond mines and placer diamond mines. According to the incomplete statistics, in 1996 there were eight diamond mines, of which three were state-owned primary diamond mines (mainly the Shandong No. 701 mine, Mengyin, Shandong, and the mine owned by the Wafangdian Diamond Co. of Liaoning) and five were town and township mines (mainly placer diamond deposits mined by local people in Hunan and Shandong). The designed diamond mine capacity is specified as follows: the mining capacity is 366,200 tons of ore per year and the dressing capacity is 330,000 tons of ore per year. Only state-owned mines have production scale. The Dingjiagang placer diamond mine at Changde, Hunan, has stopped production; town and township mines are not constructed regularly and have no definite production scale. Influenced by the variation in diamond grade, the diamond production fluctuates greatly. In the 1990s China generally produced 100,000 to 150,000 carats of diamond each year. The annual production of natural diamonds of China in recent years is shown in Table 4.12.2.

Table 4.12.2 Production of natural diamonds of China

As the production of natural diamonds is very limited and falls far short of the demand of the national economy, more than 90% of industrial diamonds are replaced by synthetic diamonds. At present there are more than 600 synthetic diamond plants in China, which produce over 400 million carats of single diamond crystals each year. The production of China's synthetic diamonds can satisfy the demands for the manufacture of diamond tools, and they have become an important component part of the ultrahard material industry. In terms of quantity China has been the largest producer of synthetic diamonds.

4.12.2.2 Distribution of Production

(1) Natural diamonds

The greater majority of China's diamond production comes from primary diamond mines of Shandong and Liaoning, and the production of placer deposits mined by local people is scarce. The main producing enterprises are as follows.

      1) Shandong No. 701 mine

       The mine is located at Changmazhuang, about 15 km west of Mengyin County, Shandong Province. It is accessible by a motor road from Mengyin to Majiazhuang.

        The first phase of the mine construction aimed to mine the Hongqi No. 1 dike in the Changmazhuang primary diamond deposit by underground method. The deposit was put into production in 1970 and stopped production in 1980. The second phase of the mine construction aimed to open-cut mine the Shengli No. 1 pipe of the Wangzhuang primary diamond deposit and was completed in 1976. The designed capacity is as follows: the ore mining capacity is 96,200 tons of ore per year, the ore dressing capacity is 90,000 tons of ore per year, and the annual production is generally 40,000 to 50,000 carats of diamonds. In 1955 the mining approached the designed lowest open-cut mining level and it was eager to turn into underground mining, so the production was in a state of semi-suspension. In 1997 the mine produced 18,577 carats of diamonds.

       The grade of primary diamond ore produced by the Shandong No. 701 mine in 1996 was 4.62 carats per ton, the grade of selected ore was 4.11 carats per ton, and the recovery of ore dressing was 81.51%. Diamond products are mainly of industrial grade, while gem diamonds take up only about 20%.

      2) Wafangdian Diamond Co.

      The mine is situated at Toudaogou, Wafangdian City, Liaoning Province, 1.5 km from the Toudaogou Station of a railway from Wafangdian to Wudao and 0.5 km from an expressway from Shenyang to Dalian. The traffic is convenient. The company is in Wafangdian City.

      The Wafangdian Diamond Co. was set up in 1987 for open-pit mining the No. 50 diamond-bearing pipe at the Toudaogou deposit, Wafangdian, Liaoning. When the first phase of construction was completed in 1990, the mine was put into production. The designed mining capacity was 270,000 tons of ore per year and the designed dressing capacity was 240,000 tons of ore per year. Since the establishment of the mine, the enterprise has achieved a sustained and sound development and the actual production capacity has exceeded the designed capacity. For example, in 1996,  500,000 tons of ore were mined and 470,000 tons of ore were dressed. In 1990 to 1997, the enterprise produced a total of 485,000 carats of diamonds, with the annual production generally ranging from 50,000 to 80,000 carats.

      The diamond ore grade of No. 50 pipe is not high, about 0.3 to 0.5 carats/ton, but the diamonds are of excellent quality. According to the statistics of the diamond production of the mine in 1997, gem diamonds account for 62% of the total production, semi-gem diamonds 13%, and industrial diamonds 25%.

(2) Synthetic diamonds

Synthetic diamond producing enterprises in China are scattered and highly varied in scale. According to the estimates of the diamond trade, in 1997 there were more than 600 synthetic diamond producing enterprises in China, of which 17 were backbone enterprises. The country's total production of synthetic diamonds was 440 million carats, of which the production of the 17 backbone enterprises was 285.7 million carats, accounting for 65% of the total production. The production of synthetic diamonds of China in recent years is given in Table 4.12.3.

Table 4.12.3 Production of synthetic diamonds of China over recent years

The distribution of China's natural diamond and synthetic diamond enterprises is shown in  Table 4.12.4.