Peculiarity Description of China’s Cobalt
The explored cobalt resources in China are characterized by three main features.
1) Most cobalt occurs in low-grade ores and is mainly recovered as a by-product. According to the statistical analysis of over 50 deposits with cobalt reserves more than 1,000 tons in China, the average grade of cobalt is only 0.02%. As a result, the metal recovery in the production process is low, with technology being complex and the production cost being high.
2) The exploitable cobalt resources are mostly associated with magmatic Cu-Ni (Co) sulfide deposits. The explored reserves of cobalt account for about 50% of the national total reserves. This type of deposits is primarily distributed in northern Gansu and southern Jilin. These two areas are situated along the edges of the North China craton. The contact of rock bodies with Paleoproterozoic strata ( 1,719 Ma) is intrusive, while the Sm-Nd isochron age of mineral separates from the rock body is 1508¡À31 Ma. Thus, the time of rock formation and mineralization is Meso- to Paleoproterozoic. The major ore minerals of the deposits of this type include pyrrhotite, pentlandite, chalcopyrite, cubanite, mackinawite, valleriite, violarite, as well as sperrylite, platinum, gold, silver, hessite, k¨¹stelite, atokite, and so on. The major gangue minerals include chrysolite, bronzite, enstatite-diopside, labradorite, etc.
Nowadays, the exploited deposits of this type include Baijazuizi in Jinchuan, Gansu Province, Hongqiling in Panshi, Jilin Province, Karatungk in Xinjiang, and others. Jinchuan is the primary cobalt occurrence in China with reserves of by-product cobalt of 144,200 tons.
The less important exploitable cobalt resources appear as a valuable by-product in skarn-type Cu-Fe deposits, explored Co reserves of which make up about 30% of the national total reserves.
Medium- and small-sized skarn type iron (cobalt) deposits, such as those in Handan, Laiwu and other areas, are mainly distributed in western Shandong, southern Hebei, central Shanxi as well as northern Jiangsu, northern Henan and other areas. All these areas are located in the central part of the North China craton. They have been influenced by tectonic movements along continental margins since the Mesozoic, and extensive tectonic-magmatic and related metallogenic activities have taken place. The duration of rock mass formation was long (170~109 Ma). The ore-forming process mainly occurred in the late Yanshanian.
Principal ore minerals are magnetite and pyrite, with subordinate chalcopyrite, hematite and limonite. Gangue minerals include diopside and serpentine with minor phlogopite, tremolite, antinolite, garnet, dolomite, chlorite, quartz, and others.
The examples of deposits of this type are mainly the Wu’an and Fushan iron deposits in Hebei, Laiwu iron deposit in Shandong, Liguo iron deposit in Jiangsu, and so on.
The skarn type iron-copper deposits, such as Daye, are distributed in southeastern Hubei, which is located along the northern margin of the ancient Yangtze block. It was connected with the North China block in the Neoproterozoic, and then separated from the latter. It remained sinking for a long time and accommodated very thick Paleozoic sediments of platform type. Sedimentogenic mineralization of iron, sulfur, and others took place locally. By the end of the late Triassic, the Yangtze plate and North China plate connected with each other again, and cover rocks experienced strong compression and formed a WNW-ENE arcuate folded uplifted zone. During the Mesozoic, this area was influenced by the activity of the West Pacific plate. NNE-NE deep fault movement was accompanied by NW and NE faults in cover rocks, forming a grid pattern tectonic system and a structural framework of uplift-alternating-with-depression. There occurred widespread magmatic activity of Yanshanian age and related regional iron, copper, gold and sulfur mineralization. The timing of rock formation and mineralization is mainly late Jurassic and early Cretaceous.As the professional manufacturer of complete sets of mining machinery, such as rotary kiln,vibrating screen, Henan Hongxing is always doing the best in products and service.
Ore minerals are predominantly magnetite and hematite, and subordinately siderite and pyrite with minor mushketovite, specularite, and so on. Gangue minerals are dominantly garnet, diopside, vesuvianite, scapolite, phlogopite, etc.
The major examples of this type of deposits include the Tieshan Cu-Fe deposit, Tonglushan Cu-Fe deposit, Chengchao Fe deposit, and others in Daye, Hubei Province.
At present, exploited deposits include the Zhongtiaoshan copper deposit in Shanxi, Daye iron deposit in Hubei, Jinling iron deposit in Shandong, Lalachang copper deposit in Sichuan, Shilu iron-copper deposit in Hainan, and others. These mines produce mainly Co-bearing pyrite concentrates.
3) China’s cobalt ore from which cobalt is exclusively recovered is earthy cobalt whose reserves make up only around 2% of the national total reserves. This type of deposits includes the Juding earthy cobalt deposit in Anding County, Hainan Province. It is located south-east of Juding Town in a basalt denuded tableland and gentle slope hills. The area of distribution of orebodies is about 12 km2. The orebodies of earthy cobalt are stratiform or compositely stratiform bodies consisting of the upper and lower ones. They occur in weathered laterite whose parent rocks are ultrabasic limburgite and basic olivine basalt erupted from late Tertiary (Pliocene) to Quaternary (Pleistocene). Cobalt ore is often associated with bauxite, belonging to the eluvial type formed by weathering and leaching.
The deposit is composed of 10 earthy cobalt bodies. The shape of orebodies is irregular. It is obviously controlled by topography and crust of weathering in plan. In profile, orebodies are thin-bedded or interbedded with laterite. The direction of dip is basically coincident with that of the slope. The dip angle is 3¡ã~12¡ã. Over the ore bed there is often a laterite cover 1 m (maximum 5 m) thick. The ore bed is exposed locally. The thickness of ore bed is usually smaller at ridges and the base of the slope, and larger at the foot of the hill. The average cobalt grade is 1.63%.
The ores of earthy cobalt consist of black or blue-black Co, Ni and Cu-bearing metamanganate, lithiophorite, K-protomelane and limonite assuming a colloform texture and nodular or concentric textures. The ores are flaky, botryoidal, globular or coralloidal. Their grain size is usually 5~30 mm.
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