4.4.1.1 Reserves and Resources

China has rich fireclay resources. By the end of 1997, the number of explored fire clay occurrences in 27 provinces (regions) totaled 328 with retained reserves of fireclay of 2,142 million tons, of which categories A+B+C reserves were 598 million tons, accounting for 27.9% of the total. Table 4.4.1 shows that since the 1970s the retained reserves of the fireclay have been basically kept at around 2 billion tons. 

It is estimated that the total resources of fireclay all over the country are about 5 billion tons. The total resources of the fireclay in the roofs, floors and interlayers of coal layers in coal fields and their adjacent areas are 5 billion tons. The bauxite suitable to be used as refractories in bauxite reserves amounts to 0.5 billion tons. The total fireclay resources in China are at least more than 10 billion tons.  

According to the information from Zhang Yuanlin, the total reserves of fireclay all over the world are about 68.5 billion tons, and they are mainly concentrated in the former Soviet Union (13.5 billion tons), UK (13.5 billion tons), USA (10 billion tons), Australia (4.5 billion tons), Brazil (3.0 billion tons), India (2.0 billion tons). 

By contrast, China has fireclay reserves of 2.142 billion tons, roughly after  Brazil and before India. But it should be indicated that there are 0.339 billion tons of high-alumina clay in all of fireclay in China. Additionally, there is a considerable amount of bauxite in our country which is recovered as refractories. According to the Subject Research and Statistics on the Geological Exploration Code for Bauxite in 1984, bauxide reserves with Al2O3 more than 55% and Fe2O3 less than 3% account for 30% of the total bauxite reserves. The mineral ores reserves are about 0.5 billion tons, equivalent to more than 0.8 billion tons of high-alumina clay. On the contrary, the high-alumina clay resources in the above-mentioned countries with rich fireclay resources are scarce, and the high-alumina clay reserves in China are much more than those that the above-mentioned countries have.

4.4.1.2 Characteristics 

According to the distribution of fireclay reserves in the provinces (regions ) of China, Shanxi leads in the reserves, accounting for 27.9% of the total reserves, followed successively by Henan 13.3%, Inner Mongolia 10.1%, Hebei 9%, Hubei 5.7%, Jilin 5.5% and Shandong 5.4%. The reserves in each of the above-mentioned 7 provinces (regions) are more than 100 million tons. Their total reserves account for 76.9% of the national total reserves. The main fireclay deposits and their development conditions in China are shown in Table 4.4.2 and Fig. 4.4.1.

According to the ore types of the fireclay in China, 83.5% high-alumina clay is concentrated in Shanxi and Henan. 80% hard clay is distributed in Shanxi, Inner Mongolia, Hebei, Liaoning, Shandong, Henan and Hubei. 68.8% soft and semi-soft clay is distributed in Jilin, Hebei, Shanxi, Hunan and Guangdong. 

In China fireclay is mostly concentrated in eastern China, near iron and steel enterprises and non-ferrous metal smelting enterprises, which provides  favorable conditions for the development of China's metallurgical industry, but one disadvantage is that the nearby fireclay fails to meet the needs of large iron and steel enterprises, such as Hubei Wuhan Steel Works, Sichuan Panzhihua Steel Works and Shanghai Baoshan Steel Works and has to be transferred through long-distance transportation from other provinces. There are many large and medium-sized fireclay deposits in China, such as the Taihushi and Baiquan clay districts at Yangqu, the Jiajianao and Guocun clay districts at Yuxian Country, the Shimo, Xihedi and Xiabao clay districts at Xiaoyi County and the Qilintai clay district at Heshun County in Shanxi, the Shecun clay district at Gong County in Henan, the Zhuyuan-Kuangkou clay district at Xin'an County and the Banbidian clay district at Tangshan City in Hebei. They are all districts of high-alumina clay or those of predominantly high-alumina clay. The alumina Content in these clay districts is usually high, and the Fe2O3 content is low, and the loss on ignition is low too. They are excellent refractories. However, generally speaking, the high-alumina clay reserves are still small, and only account for 16% of the total reserves of the country. The overwhelming majority of explored reserves are hard clay ( 65%) and semi-soft clay (19%). 

Another disadvantage of China's fireclay deposits is that there are many medium and low-grade fireclays but scarce good quality fireclays. According to the statistics, in the whole high-alumina clay reserves the extra-high grade fireclay accounts for only 7.1%, and the first-grade one accounts for 22%. In all hard clay reserves, the extra-high grade fireclay accounts for only 3% and the first-grade one accounts for 35%. In all soft clay and semi-soft clay reserves, the first-grade ore accounts for only 17%. So, whether for high-alumina clay or for hard clay and soft clay (semi-soft clay), the second- and third-grade fireclay occupies the greater majority.

The last characteristic of Chinese fire clay deposits is that: there are less deposits producing fireclay alone and more deposits producing fireclay as a by-product. According to the statistics, the reserves of deposits producing fireclay alone only account for 30% of the total national reserves. Those producing fireclay as a by-product in other principal ores (such as coal, bauxite and iron ores) account for 40%. Those deposits in which fireclay is the essential mineral but other minerals are mined as by-products account for 30%. So, total utilization of fireclay has important significance for the development of China's fireclay mining industry. 

The overwhelming majority of fireclay in China is of sedimentary origin, and their minerogenetic epochs are the Devonian, Carboniferous, Permian, Triassic, Jurassic, Tertiary and Quarternary, of which the main ones are the Middle and Late Carboniferous, Late Permian and Tertiary.

Table 4.4.2 Main fireclay deposits in China

The most important minerogenetic epochs of fire-clay in China is Middle-Late Carboniferous. The fireclay occurrences are widely distributed with persistent horizons and a large scale. The ore layers occur in the basal part of the Upper Carboniferous or in Middle Carboniferous Benxi Group and are  located on the erosional surface of Ordovician or Cambrian Carbonate rocks. High-alumina clay is the Chief ore type. Hard clay is also important, and there is a certain amount of soft clay. They are mainly distributed in Shanxi, Henan, Hebei, Inner Mongolia, Guizhou and Shaanxi.  

The Late Permian Epoch was an important minerogenetic epoch for hard clay in China. Fireclay occurrs in the middle part of the Upper Permian and is widespread and persistent stratigraphically. The occurrences are mainly distributed in Shandong, Anhui, Fujian, Zhejiang, Jilin, and Liaoning. 

The fireclay deposits formed in the Tertiary minerogenetic epoch are large and mainly contain soft clay. Fireclay layers occur in the Tertiary Shulan Group,  underlain unconfor-mably by the Hercynian granite and the Cretaceous. It is the product of formation of the graben basin. The deposits of this type are mainly  distributed in Northeast China, such as the Shuiquliu deposit in Jilin and the Huanghuabeishan deposit in Heilongjiang. 

In space, fireclay in China is mainly distributed in North China and its adjacent areas, such as Shanxi, Hebei, Inner Mongolia, Henan and Shandong. There are also some large and medium-sized fireclay deposits in Guizhou, Sichuan and Hubei in Southern China. Such distribution is mainly controlled by tectonic and paleogeographical conditions. Tectonically, the deposits of industrial value are all distributed in tectonically stable regions inside platforms. The long period of mineralization was benefitial to the enrichment of ore substances, resulting in the formation of good-quality and large-sized fireclay  deposits. In terms of the paleogeographical locations the deposits of industrial value are mostly distributed on edges of cratons or of areas sustained long-continued denudation. The most favorable geographical locations were bays on edges of cratons, lake basins, swamps and lagoons in the paralic plains and restricted sea basin with barriers. In terms of the time and space of mineralization, they were mostly deposited in the initial stage of transgression after long-term interruption and on the bottom of transgressive overlapping deposits.