4.6.2.1Present State of Production

Up to the end of 1997, China had developed 46 mining areas of mirabilite-group minerals, of which 21 were mirabilite mining areas, 2 thenardite mining areas and 23 glauberite mining areas. The mining areas that had been developed and utilized were dominated by large and medium-sized deposits.

By 1997, China's total production capacity of active mines and mines under construction in respect to mirabilite-group minerals was 7.68 million tons of ores per year, of which mirabilite mines contributed 3.96 million tons per year, thenardite mines 720,000 tons per year and glauberite mines 3 million tons per year. According to the statistics, in 1997 the ore production of China's mirabilite (including glauberite) mines was 7.159 million tons, valued at 896 million RMB yuan (US $ 108 million) and in 1998 the ore production was 7.48 million tons, valued at 932 million RMB yuan (US  $ 111 million).

China is not only a major source of mirabilite resources but also one of the major produ-cers of anhydrous sodium sulfate. At present there are a total of 62 enterprises of sodium sulfate production with an annual production capacity of about 2.58 million tons. They are mainly concentrated in Sichuan, Shanxi, Inner Mongolia, Gansu and Xinjiang. The production capacities of these provinces and autonomous regions constitute more than 80% of the total national production capacity.

China's sodium sulfate production was 1.2668 million tons in 1991, 1.9925 million tons in 1994, 2.582 million tons in 1996 and 1.964 million tons in 1997.

The provinces or autonomous region that produce considerable amounts of sodium sulfate are Sichuan, Shanxi, Xinjiang, Gansu and Inner Mongolia, of which Sichuan and Shanxi lead in the production with their combined production accounting for 68.1% of the national total in 1997.

China has not only very abundant mirabilite resources but also quite abundant by-pro-duct sodium sulfate. China can recover about 1 million tons of sodium sulfate every year from effluents of production of formic acid, oxalic acid, boric acid, chromate AC foamer, chemical fiber, TNT etc. Of the 1 million tons of sodium sulfate, 550,000 tons can be recovered from production of organic and inorganic chemicals of the chemical industrial sector; 200,000 tons from the salt sector;  240,000 tons from chemical fiber production; 120,000 tons from nylon production and 50,000 tons from the dyeing industry in the light industrial sector. But actually the recovery is very low. For example, the by-product recoveries of sodium sulfate in the salt industry and chemical industry are only 46% and <30% respectively, and sodium sulfate in the dyeing industry has not been recovered yet now. The anhydrous sodium sulfate recovered as a by-product abroad now takes up more than 50% of the total amount, whereas the by-product anhydrous sodium sulfate in China accounts for only about 10% of the national total.4.6.2.2Production DistributionChina's mirabilite mining areas that have been developed and mined are mainly distrib-uted in Xinjiang, Gansu, Inner Mongolia, Shanxi and Shaanxi. The main operating mines are presented in Table 4.6.1.