WOLLASTONITE

Wollastonite, a metasilicate mineral of calcium and a kind of industrial mineral material, is mainly used at present in the ceramics industry, and less commonly as protective slag for metallurgy, raw materials of paint, coatings of electrods, substitute products for asbestos, abrasive adhesives and additive of glass, as well as coatings for rubber, plastics, insulating material and paper. Some wollastonite rocks can also be used as architectural decoration material and additives of white cement. 

Development and utilization of wollastonite started late  in China. It was in 1975 that the Xiaojipu wollastonite deposit was firstly found and explored in Xia Malin, Dayie County, Hubei Province. The products of wollastonite began to be produced in 1979, and then many mines came on stream, such as wollastonite mine in Daxiangshan mine in Lishu County, Nancuocao mine in Panshi County, Tiegongshan mine in Lishu County and Xilinhe mine in Longjing City, Jilin Province; the Chengzishan mine in Faku County, Liaoning Province; and the Lijiaxiang mine in Changxing County, Zhejiang Province. Some small-sized mines were put into production one after another. For two decades the development of wollastonite deposits in China has begun to take shape. The output of wollastonite in China was only 4,700 tons in 1981, but it reached was already 0.25 million tons in 1997 according to the statistics from China Non-metallic Minerals Association. Among them 0.1233 million tons were produced from large and medium-sized mines, 0.1257 million tons from small-sized mines. China has become one of important wollastonite mining countries in the world.

4.14.1 Resources

4.14.1.1 Reserves and Resources

China is one of the countries with the richest wollastonite resources in the world. Exploration of wollastonite began late in China, but for two decades from 1975 on, hundreds of occurrences have been found in 17 Provinces (autonomous regions). It is estimated that the resources of wollastonite reach nearly 200 million tons. By the end of 1997, 33 wollastonite occurrences with retained reserves (6 superlarge, 10 large,9 medium-sized and 8 small occur-

Fig. 4.14.1Map of distribution of wollastonite occurrences in China
1. Bayan Nur lead zinc mine (paragenetic), Bairin Zuoqi, Inner Mongolia; 2. Fushan, Jianping County, Liaoning Province; 3. Shangtanyao, Faku County, Liaoning Province; 4. Chengzishan, Faku County, Liaoning Province; 5. Quanyangou, Tiefa City, Liaoning Province; 6. Dadingshan segment in Dadingshan mining area, Lishu County, Jilin Province; 7. Tiegongshan segment of Dadingshan mining area, Lishu County, Jilin Province; 8. Qianmajiayoufang, Lishu County, Jilin Province; 9. Changweizi, Panshi City, Jilin Province; 10. Nancuocao, Panshi City, Jilin Province; 11. Mengjia, Panshi City, Jilin Province; 12. Xicuocao, Yima Town, Panshi City, Jilin Province; 13. Bizigou, Huadian City, Jilin Province; 14. Xilinhe, Longjing City, Jilin Province; 15. Haisi, Dulan County, Qinghai Province; 16. Miaoxi, Guangde County, Anhui Province; 17. Xiaomeiling, Liyang County, Jiangsu Province; 18. Lijiaxiang, Changxing County, Zhejiang Province; 19. Miaoxi, Huzhou City, Zhejiang Province; 20. Baishi rock, Mingguang town of Tengchong County, Yunnan Province; 21. Yueguangshan, Xinyu-Shanggao, Jiangxi Province; 22. Lines 32-35 line in Yueguangshan, Xinyu-Shanggao , Jiangxi Province; 23. Chaofangmiao, Renhe Town, Xinyu City, Jiangxi Province; 24. Shuidixia, Changning County, Hunan Province; 25. Chaotian, Lianzhou City, Guangdong Province.

rences) have been explored. The total retained wollastonite reserves of categories B+C+D amount to 134.28 million tons.  

Of China's retained reserves of wollastonite, reserves of categories B+C account for 29% of the total. Geological prospecting has been conducted in only one among occurrences with retained reserves. For some mines only  reconnaissance has been made and the extent of geological prospecting work is low. Of occurrences of wollastonite with retained reserves, 19 occurrences (3 superlarge, 6 large, 6 medium-sized and 4 small occurrences) have been mined. The total retained reserves exceed 77 million tons, or account for 58 percent of the total retained reserves of wollastonite, which can meet the needs of China's wollastonite industry till 2010 and beyond. Furthermore, 11 occurrences ( including 3 superlarge, 3 large, 1 medium-sized and 4 small ones ) with retained reserves more than 48 million tons, which account for 36% of the total retained reserves, can be chosen to be exploited in the near future. In the near future, 3 occurrences (including 1 large and 2 medium-sized occurrences), are difficult to use, and their total retained reserves reach nearly 8 million tons, accounting for 4% of the total retained reserves of wollastonite.

4.14.1.2 Characteristics

The map of distribution of China's 25 large (including superlarge) and medium-sized wollastonite occurrences with retained reserves as of 1997 is shown in Fig. 4.14.1.  China's wollastonite deposits are distributed in 13 Provinces and autonomous regions, mainly in the Jianping-Faku area of Liaoning Province and the Lishu-Panshi-Longjing area in Jilin Province in Northeast China. Major occurrences of wollastonite are in Jilin Province, and their retained reserves are more than 54 million tons, accounting for 40% of the total in China. Three ore districts are distributed from west to east in Dadingshan-Shiling of Lishu County, Changweizi-Shizhui in Panshi City and Xilihe of Longjing City. There are 10 retained occurrences (4 superlarge, 2 large, 3 medium-sized and 1 small occurrences). Some mineral occurrences are remained to be explored. Among the wollastonite-rich rocks in the Hunjiang area in the south of Jinlin Province, there are thick-bedded tremolites and wollastonite mineralized layers. These are important characteristics for ore finding. The area including the Dandingshan mine of Lishu County, Changweizi mine and Nancuochao mine in Panshi and Xilinhe mine in Longjing, Jilin Province, is the most important production base of wollastonite in China. There are more than 12 million tons retained wollastonite reserves in Faku County in the north and Jianping County in the northwest of Liaoning Province. The Chengzishan mine and Shangtanyao mine in Faku, which are the main occurrences of wollastonite and also the major production areas of wollastonite in China, have been already mined. Furthermore, there are also several small occurrences distributed in Mishan City of Heilingjiang Province. 

Jiangxi Province in eastern China is also one of the main areas of occurrences of wollastonite, with retained reserves more than 16 million tons. The Chaofangmiao deposit in Xinyu City has been mined. The mining area in Xinyu-Shanggao is superlarge in size and should be further explored. New occurrences have been found in Mengshan in Shanggao County and Tieshan in Shangrao City. There are 8 million tons of retained reserves of wollastonite in the border area of Zhejiang, Anhui and Jiangsu Provinces. The mines in Lijiaxiang, Changxing County, Zhejiang Province, Miaoxi, Guangde County, Anhui Province and Xiaomeiling, Liyang City, Jiangshu Province have been mined and have become the main production areas in southern China. Furthermore, many mineral occurrences have been found in the areas from Huanning to Tongling in Anhui Province along the Yangtse River. 

There is one retained occurrence of wollastonite respectively in Hubei, Hunan, Guangdong and Guangxi in south-central China, with retained ore reserves totalling nearly 4 million tons. The Chaotian mine (large) in Lianzhou City, Guangdong Province, Xiaojipu mine (small) in Daye City, Hubei Province and Nanyuandong mine (small) in Pingle County, Guangxi Autonomous Region have been mined. Some mineral occurrences in Date-Yangxin in Hubei, and Dayishan, Changning County in Hunan Province remain to be explored. 

There are superlarge wollastonite deposits in Baishiyan, Mingguang Town, Tengchong County in southwestern Yunnan Province in southwestern China, and Haisi, Dulan County in central part Qinghai Province in northwestern China, with retained reserves of 23.93 million tons and 13.15 million tons respectively, and are available to use or need to be further explored. Furthermore, wollastonite mineral occurrences have been found in the Hami area, Xinjiang. In North China, no better wollastonite occurrences have been found yet. There is only one associated  medium-sized wollastonite deposit found in the Bayan Nur lead-zinc deposit in Bairin Zuoqi, Inner Mongolia. Mineral occurrences have been found in Xiaoxiying, Qianxi County, Hebei Province. 

China's wollastonite deposits may be divided into 3 types: contact metamorphic, skarns (contact metasomatic) and regional metamorphic types. The contact metamorphic type of deposits is the most important type, and their retained reserves account for 80% of the total retained reserves. These deposits formed by metamorphism of silicon-rich limestone due to baking of intrusive bodies, and are usually located in hornsified-marbleized exocontact zone between intermediate-acid and acid intrusive rocks and carbonate rocks. They are generally several tens of meters and even more than a thousand meters away from the rock body. The ore bodies usually occur in the stratified, stratoid or lenticular shape with a length from a few hundred to more than a thousand meters and a width from several to several tens of meters and even more than a hundred meters. The size of deposits is mainly large and superlarge. The ores are of wollastonite-quartz-calcite type. Their mineral assembleage is rather simple and the ore quality is good with an ore grade (content of wollastonite or ore-bearing coefficient) of 20%~70%, more than 50% generally. The grade of rich ores reaches 95%. These are the main mining object in China. The deposits distributed in Jilin, Liaoning, Zhejiang and Jiangxi Provinces belong to this type. Most of skarns type deposits are distributed in the exocontact zone of intermediate to acid intrusive rocks with siliceous limestone. A few of them occur inside intrusive rock bodies and country rocks. The shapes of the ore bodies are variable. They occur discontinuously and form an ore belt with a length from several meters to several hundred meters and a thickness from several meters to forty or fifty and even seventy or eighty meters. The ores are of skarns rock type with a complex mineral composition. The grade of ores is mainly between 40%~60%, and exceptionally reaches 68%. The harmful component Fe2O3 in part of deposits is higher. In some cases wollastonite is associated with nonferrous metals, so is difficult to mine and dress. Deposits of different sizes distributed in Hubei, Jiangsu, Hunan and Qinghai and so on belong to this type. Now the regional metamorphic mineral occurrences have only been found in the Hunjiang area in southern Jilin Province, and there are no explored reserves. 

China's wollastonite deposits are mostly hosted in cover formations since the Cambrian , and mainly occur in the Carboniferous and Permian in Cambrian,  Devonian and Silurian. The intrusive rocks associated with mineralization are mainly Yanshanian,Indosinian and Hercynian intermediate and acid magmatic rocks.  

China's wollastonite deposits are mainly distributed in three geosynclinal fold systems. The Jilin-Heilongjiang fold system with many large mineral deposits  are the most important tectono-magmatic unit, followed by the South China fold system and Shanjiang fold system. There are small mineral deposits on margins of the Yangtze platform and North China platform. The intermediate and acid intrusive rocks associated with mineralization are mainly hypabyssalepizonal to medium granite, porphyritic granite, granodiorite porphyry, syenodiorite-porphyry and quartz porphyry. The host rocks are generally marine carbonate rocks containing siliceous components like chert nodules and chert bands. 

The grade of wollastonite ore in China is high. According to the incomplete statistics, there are 4 deposits with an average grade (mineral content, similarly hereinafter) of wollastonite between 79.03%~71.90%. Their retained ore reserves are more than 20 million tons, accounting for 15% of the total, and are mainly distributed in Guangdong, Jilin Provinces. There are 6 deposits with an average grade within 69.21%~60.84%. Their retained reserves are more than 22 million tons, accounting for 16% of the total, and are distributed in Qinghai, Zhejiang, Anhui and Jiangsu Provinces. There are 9 deposits with an average grade within 57.10%~50.00%. Their retained reserves are more than 42 million tons, accounting for 32% of the total, and are distributed in Jilin, Liaoning and Zhejiang. There are 10 deposits with an average grade within 45%~39.98%. Their retained reserves are more than 25 million tons, accounting for 19% of the total, and are distributed in Liaoning, Hunan, and Inner Mongolia. 

The quality of wollastonite in China is good. The ore quality of many deposits in Jilin, Liaoning, Hubei, Zhejiang, Jiangxi and Qinghai is almost as good as that of famous Indian wollastonite. It is especially the case with the wollastonite ores in the Dadingshan wollastonite mine, Lishu County, Jilin Province, which are characterized by white color, low impurity content, and acicular or fibrous crystalls and so are the natural, low-iron superior wollastonite rarely seen in the world. The quality and varieties of their products reach the advanced standard in the world, and enjoy the high prestige in the international market.

Limestone commonly occur together with wollastonite in the deposits and  can be mined as a by-product, and besides diopside and tremolite, which can be used as raw materials for architectural ceramics, can also be mined as valuable by-products. However, non-ferrous metal minerals such as copper, lead and zinc associated with wollastonite in skarns type wollastonite deposits are of little value for recovery.  

The development conditions of wollastonite deposits in China are better. They are easily accessible and most deposits are suited to open-pit mining. The ores are dressed by magnetic method and floatation method with good results.