2.4.1.1 Status of the Resources

China has discovered 59 uranium minerals, but only a few are usable in industry.

Uraninite (UO2) is the most useful mineral. As it varies greatly in crystal behaviors as well as physical and chemical properties, geologists divide it into three minerals, uraninite, pitchblende and uranium blacks. Among them, pitchblend is of the greatest importance for industry, and therefore the major uranium mineral in present deposits explored. Next is the uraninite, which is found in pegmatitic uranium deposits in China. But they are not mined yet. Uranium blacks are not well developed in uranium deposits and so have no commercial values.

The uranium minerals first found in China include brannerite, furongite, xiangjiangite, yingjiangite and tengchongite, most of which have no use for industry.

Up to the present more than 200 uranium deposits have been explored in China, with substantial amount of resources submitted.

China's uranium resources are grouped into two categories, the known (discovered) and undiscovered (predicted), each of which can be subdivided into sub-categories. This classification is consistent with the international practice.

The known resources of some uranium fields (deposits) are given as follows:

Xiangshan uranium field, 26,000 tons of U;
Xiazhuang uranium field, 12,000 tons of U;
Qinglong uranium field, 8,000 tons of U;
Chanziping uranium field, 5,000 tons of U;
Chenxian uranium deposit, 5,000 tons of U;
Tengchong uranium deposit, 6,000 tons of U;
Lantian uranium deposit, 2,000 tons of U;
Ili uranium deposit, 6,000 tons of U.

The known resources consist of the reliable and prospective ones.

1) The reliable uranium resources are those of high certainty, possessing the necessary data for designing a mine. These are mainly distributed in Hunan, Jiangxi, Guangdong and Guangxi, making up about two thirds of the total.

Based on the price fluctuations in the world markets in the past ten-odd years and the recovery cost grade classified by the International Atomic Energy Agency, most of China's reliable uranium resources have good or fairly good economic values, and can provide guarantees for the short- and medium-term development of nuclear power generation.

2) The prospective resources refer to those with a fairly high certainty, but are limited in quantity and of poor economic conditions.

According to analysis of available data, China is a country rich in uranium resources in terms of the known resources. And, in view of China's geological conditions for uranium metallogeny, the situation of uranium resources in the peripheral countries and the achievements made in uranium prospecting in recent years, many Chinese geologists are confident in finding more uranium resources in China, which they estimate to reach 1 to 2 million tons.

The uranium deposits so far discovered are unevenly distributed. Although they are found in 23 provinces (regions) of China, they are concentrated in Jiangxi, Guangdong, Hunan, Guangxi, Xinjiang, Liaoning, Yunnan, Hebei, Inner Mongolia, Zhejiang and Gansu, among which the first four host most of the resources. In terms of the type of deposits, there are the following characteristics: the granite-type uranium deposits occur mainly in Guidong of Guangdong, Zhuguangshan of South China, Taoshan of Jiangxi and Beijiling of Northwest China; the volcanic-type ones mainly in Xiangshan of Jiangxi, Xiaoqiuyuan of Zhejiang, Baiyanghe of Xinjiang and the volcanic area on the north margin of the North China platform; the sandstone-type ones in the Ili basin of Xinjiang, the Xunwu basin of Jiangxi, the Hengyang basin of Hunan, the Jiangchang basin of Liaoning and western Yunnan Province; and the C-Si-mudstone-type ones in the Huangcai and Laowolong areas of Central China, Chanziping of Guangxi and the Ruoergai area bounded by Sichuan and Gansu. Fig. 2.4.1 shows the localities of the uranium deposits.

2.4.1.2 Characteristics of the Resources    
 
China's uranium resources have the following five characteristics:

1) The deposits are dominated by medium or small sizes. However, in some uranium fields, they often occur in groups consisting of a few to several tens of deposits, having one to two main bodies with concentrated resources. We have not found in China so far deposits with uranium resources up to tens of thousand tons or large to superlarge uranium fields over hundred thousand tons.

2) In the uranium resources already explored, those of the granite-type, sandstone-type, volcanic-type and C-Si-mudstone-type deposits are dominant, which have the following proportions:

granite-type: 37.05%;
sandstone-type: 23.53%;
volcanic-type: 18.97%;
C-Si-mudstone-type: 15.94%;
other types: 4.51%.

3) The ores are mainly of medium to low grades; those with grades of 0.05~0.3% account for most of the total resources. Ores in volcanic-types deposits are of higher grades; some individual deposits may have an average grade of 0.5%, but none with the average grade as rich as n% have been ever found. Recently, economically beneficial interlayer oxidized zone sandstone-type uranium deposits have been found in China, with are of low grades but can be mined with the in-situ leaching method. The lowest boundary grade may be reduced to 0.01%.

4) Uranium deposits usually have a simple composition of ores, which are mainly mono-uranium-type ores. Only in some individual deposits can be found associations with other elements, forming U-Mo, U-Hg, U-Cu, U-polymetallic and U-Th-REE deposits. In the interlaytr oxidized zone sandstone-type uranium deposits, Mo, Se, Re and V are often associated, in which Re can be recovered by in-site leaching. Besides, germanium has been found in uranium-bearing coal deposits in Southwest China. Some are dominated by germanium, forming superlarge germanium deposits rarely seen in the world.

5) Compared with some large uranium deposits of the world, the burial depths of those in China are much small in terms of the vertical amplitude: some hydrothermal-type mineralizations in other countries exceed 2 km, whereas most deposits in China are within 500 m, occasionally reaching 700~1,000 m. Some orebodies are often constrained within a certain range of elevation, forming a "metallogenic crust".

The metallogenic epochs are dominated by Meso-Cenozoic, and concentrated between 87 and 45 Ma, i.e. Cretaceous-Paleogene. There are different types of uranium mineralization formed at different metallogenic stages. They are, according to the time of occurrences, the migmatite type, pegmatite type, granite type, volcanic type, C-Si-mudstone type and sandstone type. Uranium mineralizations often show a multi-stage character in a same ore district, field or even a deposit. There are generally 2~3 metallogenic stages in hydrothermal deposits, but only one is the main stage. For example, there are three stages for the alkali-metasomatic uranium deposit in the Longshoushan area: 410~385 Ma, 245~229 Ma and 124~99 Ma, in which the first one is the main metallogenic stage. Volcanic-type uranium deposits usually have two metallogenic stages, e.g., in the Guyuan deposits on the northern margin of the North China platform, the two metallogenic stages are 115~90 Ma and 34.1~23.7 Ma respectively.

According to the mineralization types and metallogenic epochs of China's uranium deposits and their distribution in the tectonic units, the following uranium provinces can be classified:

1) The East uranium province

It begins from Guangdong Province in the south, goes through the South China and North China areas and extends to Heilongjiang Province in Northeast China. It is over 3,000 km long from north to south and 1,000 km wide from east to west. It is a part of the global marginal-Pacific uranium province, which goes northward to the Far East area of Russia and extends to the Chukochi area. Besides, some exogenic uranium deposits with resources exceeding ten thousand tons have been found in southeastern Mongolia. Most of China's uranium deposits are distributed in this metallogenic province. In addition to those formed during the Indosinian and Yanshanian movements, also found in China are the Lianshanguan migmatite-type deposit formed in the Wutaian movement and the Motianling granite-type deposit formed in the Caledonian movement. All the uranium deposits are distributed in the old blocks of the marginal uplifts, shields and folded zones of mobile platforms.

According to the distribution characteristics of the deposits, this metallogenic province can be further divided into the Jiangnan, Qinling and Yanliao metallogenic districts.

2) The Tianshan-Qilianshan uranium province

It starts in the west from the boundary line of China (Xinjiang Uygur Autonomous Region) and extends eastward to the Qilian area, with a length of over 2,000 km and a width of over 1,000 km in the western part, which narrows toward the eastern part to only 400~500 km. This province is a part of the global Ural-Tianshan-Mongolia uranium metallogenic province. The types of uranium mineralization found within China include the sandstone-type, granite-type, volcanic-type, U-bearing coal-type and pegmatite-type. The sandstone-type and U-bearing coal-type deposits are distributed on the border of intermontane basins, while the others occur in the mobilized median mass or uplifts.

This metallogenic province can be divided into the Tianshan and Qilian districts.

3) The West Yunnan metallogenic province

It is located on the Himalayan folded belt, which extends westward to Iran and southward to Indonesia.

The mineral assemblages of uranium ores differ with the various types of uranium deposits, so suitable hydrometallurgical technology should be adopted to raise the technical and economic specifications.

In stockwork and network deposits of the granite type, the ores have a simple composition; mostly occurring as an individual mineral, suitable for the acid leaching method. Ores of the metasomatic type are also simple in composition, containing beryllium sometimes. The uranium occurs as an individual mineral or adsorbed. The ores will consume a large quantity of acids, so alkaline leaching may be preferable.

Ores in stockwork and network deposits of the volcanic type are relatively complicated in composition; molybdenum may sometimes be of industrial value, and uranium occurs mainly as a mineral, so that acid leaching is preferable. Those of the metasomatic type are simple and acid-consuming, therefore the alkaline leaching may be used.

Ores in synsedimentary uranium deposits are simple in composition, in which uranium occurs in mineral or adsorption forms, suitable for acid leaching. Those in hydrogenous sedimentary deposits often contain elements such as Se, Ga, Sc, Re, V and Mo, some of which may be recovered and utilized. As the infiltration coefficient is large in the area, containing rich water, the in-situ leaching method may be used. In the coal-type uranium deposits, the ores often contain Se, Re, Mo, V, Ga and Ge, and uranium is mainly adsorbed, so that combustion is made first before the extraction.

The C-Si-mudstone type deposits are divided into the infiltration superimposition type and the hydrothermal superimposition type; ores in the former are simpler, and acid leaching can be used for both.