[Foreign niobium ore resources] The world is rich in niobium ore resources and has huge reserves. According to the statistics of the US Geological Survey, in 1999, the world's niobium metal reserves were 3.5 million tons, and the reserve base was 5.6 million tons (excluding China and Russia).
The main industrial types of niobium ore in foreign countries are carbonatite weathering crust type, niobite granite (pegmatite) type and placer type. 3 types. Among them, the carbonatite weathering crust type is the most important, accounting for more than 90% of niobium resources. It is mainly produced in Brazil, Russia, Gabon, Australia and other countries. The niobium-containing industrial mineral is pyrochlore. The reserves of niobium-tantalite-bearing granite and granite pegmatite deposits account for a small proportion of all kinds of niobium deposits, accounting for about 1%. The main component of this type of deposit is niobium-tantalite, which is often associated with cassiterite and is generally recovered as a by-product of cassiterite mining. Niobium-containing placer is generally small in scale, but placer is easy to mine and select, and is often produced together with tantalite and cassiterite, so it has certain economic significance. The cassiterite concentrate containing niobium iron ore-tantalite obtained from placer mining in Thailand, Malaysia, Zaire, Australia and other countries, the slag left after smelting crude tin contains 10% to 20% of Nb2O5 is recovered as an important by-product.
[Domestic niobium ore resources] The Bayan Obo deposit is the largest niobium ore in my country, containing 63.4% of the country's proven niobium reserves And 82.7% of industrial reserves, the vast majority of niobium ore reserves are concentrated in large and medium-sized deposits. The types of niobium deposits in my country mainly include Bayan Obo type iron-niobium-rare earth deposits, alkaline rock-carbonatite type deposits, granite and alkaline granite type deposits, granite pegmatite type deposits and placer deposits.
In the Bayan Obo deposit, niobium-rare earth ore is distributed in iron ore bodies, dolomite and slate, and is produced in thick layers and layers. The rock layers in the entire ore belt are generally mineralized with niobium and rare earth. industrial ores have : ① Magnetite ore, Nb2O5 average grade 0.126%～0.141%; ② Dolomite ore, Nb2O5 average grade 0.110% ~0.168%. Niobium-containing minerals include niobite, niobium calcite, and niobium rutile. Because niobium minerals are embedded with fine particles (20m), and coexists with iron and rare earths, the beneficiation problem of niobium has not yet been solved, and currently only low-grade ferroniobium can be produced.
The alkaline rock-carbonatite type niobium deposit is represented by the Miaoya syenite-carbonatite type niobium and rare earth deposits in Zhushan County, Hubei Province. Carbonatite and syenite containing niobium and rare earth form a complex. Isotopic age 255 million years. The main niobium minerals are niobite and niobium rutile. Niobite is mainly enriched in biotite carbonatite, and niobium rutile is enriched in mixed syenite and syenite porphyry. At present, the Miaoya deposit has not been developed and utilized.
Granite-type niobium deposits are relatively developed in my country, and there are many mineral deposits. The more important ones are Jiangxi Yichun 414 Mine, Guangxi Gongcheng Limu Mine, Hunan Chaling Jinzhulong Mine, Guangdong Boluotaimei Mine, etc. The scale of these deposits is mainly medium-sized. , the second is small, there is no large niobium ore, and the grade is generally low (Nb2O5, 0.01% to 0.02%). The industrial mineral is tantalum-bearing niobium iron ore, which is one of the sources of niobium concentrate in my country. Alkaline granite-type niobium mines are generally large in scale and relatively high in grade. For example, Inner Mongolia Zhemeng Balzhe Mine has not yet been developed and utilized due to its complex ore composition and low recovery rate.
Granite pegmatite-type niobium ore is currently the main source of niobium concentrate in my country. The Huangshan Mine in Hengfeng County, Jiangxi Province is the most important deposit of this type. There are more than 70 granite pegmatite veins in the mining area distributed in the outer contact zone of the Yanshanian granite body. The industrial minerals are niobite and titanium-tantalum-niobium ore. , the size is medium.
There is also an alkaline pegmatite-type niobium ore, which is found in the Luku mining area of Huili County, Sichuan Province. The alkaline pegmatite dykes and albite dykes in the mining area are produced in the Gabbro in the contact zone of the Indosinian alkaline syenite in vitro. In the phase band, the vein body is complex in shape and the zonation is not obvious. The niobium mineral is cerium uranium pyrochlore, with good selectivity, medium scale, and rich grade (0.17%). But it has not been exploited yet.
To sum up, the niobium ore resources in my country have the following characteristics: ① The origin is widely distributed and the resources are relatively concentrated. Proven niobium deposits are distributed in 17 provinces and regions in the country, but are highly concentrated in Inner Mongolia and Hubei provinces. It accounts for the national niobium resources 95.5%; ② The Nb2O5 grade of niobium ore used in my country is 0.0083% to 0.0437%, which is much lower than that of foreign niobium ore; ③ The symbiotic minerals are complex, and the beneficiation and smelting are difficult.
Several large-scale niobium mines in my country, including Bayan Obo, Balzhe, Miaoya, etc., are multi-component rare rare earth co-associated ores with fine mineral particle size, difficult dressing and smelting, and low recovery rate, generally 23.61% to 47.64%. The concentrate grade is also low (2.80% to 34.62%); ④ The mineral resources are large, but the available mineral fields and reserves are very few.
[Foreign tantalum resources] According to the statistics of the United States Geological Survey, the foreign reserves of Ta2O5 are 17,100 tons, and the reserve base is 29,300 tons. Mainly distributed in Australia, Nigeria, Congo, Canada and Brazil and other countries. Although new deposits have been discovered in recent years, they have remained largely unexploited.
At present, granite pegmatite type and cassiterite-wolframite hydrothermal type are still the main industrial mining types of tantalum ore abroad. Granite pegmatite-type tantalum mines are mainly distributed in Australia, Canada, Brazil, Russia and some African countries. Among them, the Greenbushs deposit in Australia is the most famous. It is currently the largest tantalum mine in foreign countries and has Ta2O5 reserves. 9600 tons, with an average grade of 0.044%, in addition to niobium, lithium, tin and other resources, with an annual output of 254 tons of Ta2O5.
Cassiterite-wolframite hydrothermal deposits are also an important source of tantalum in foreign countries. In some tantalum-rich cassiterite-wolframite deposits and their surrounding placers, the Ta2O5 content in cassiterite can reach up to 1% to 30%, generally 1.8% to 15%. The slag left from smelting crude tin contains 1.5% to 10% Ta2O5, which is an important raw material for extracting tantalum. world tantalum production About 1/3 is extracted from smelter cassiterite, wolframite slag and filter residue. 90% of tantalum production in Thailand and Malaysia comes from this slag.
[Domestic tantalum resources] my country's tantalum mines are mainly concentrated in Jiangxi, Hunan, Fujian, Guangxi, Guangdong, Xinjiang and Inner Mongolia and other provinces Area. And the national tantalum reserves are highly concentrated in large and medium-sized deposits. The type of tantalum ore industry in my country is different from that in foreign countries, mainly granite type, accounting for 77.3% of the proven reserves ; And the granite pegmatite deposits are second, accounting for 19.4% of the proven reserves. There are also hydrothermal deposits containing cassiterite and wolframite in my country, but the ore grade is not as high as that in Southeast Asian countries, and the scale of the deposit is not so large. Most of the tantalum ores in my country are co-original deposits such as tantalum, niobium, lithium or tantalum, niobium, tungsten, tin or tantalum, niobium, beryllium, zirconium, rare earth, etc., and only a few are tantalum-niobium deposits.
Granite deposits are also the main source of tantalum concentrates in China. Mostly large and medium-sized deposits, Yichun, Jiangxi Mine 414 is an extra-large deposit and is currently the largest tantalum concentrate mine in China. Such deposits are generally large in scale, uniform in grade and low in Ta2O5 The content is generally between 0.01% and 0.016%. The industrial mineral of tantalum is niobium-tantalum manganese ore, and there are different amounts of high-tantalum mineral-fine spar. There are many components available for comprehensive utilization in the deposit, in addition to tantalum and niobium, there are tin, tungsten, lithium, rubidium, cesium and so on. The mining conditions of the deposit are good, and most of the deposits are suitable for open-pit mining.
Granite pegmatite-type tantalum deposits are mainly distributed in Xinjiang Altay, East Qinling, Northwest Sichuan and West Fujian. Important deposits are Kelumite and Keketuohai in Xinjiang, Xikeng in Fujian, and Jika in Sichuan. Pegmatite deposits are currently the second source of tantalum concentrates in China. The grade is generally lower than that of foreign pegmatite mines, generally <0.01% to 0.028%.
Wolframite - the associated tantalum (niobium) ore in the cassiterite hydrothermal vein type deposit, its grade is relatively high, the Ta2O5 content is 0.041% ~ 0.13%, but the reserves are not large, accounting for only 3.3% of the national reserves. Mainly concentrated in the southern Jiangxi area.
The alkaline granite-type tantalum-niobium deposit in Suzhou is a major discovery in the prospecting of tantalum ore in China in recent years. The scale of the mine is super large, and the grade of tantalum and niobium is higher than that of granite-type deposits currently mined in China. The tantalum-niobium-rich granite is composed of biotite-rich granite and albite-rich granite at the edge and top of the Suzhou main pluton. The study of the occurrence state of tantalum shows that there are 77.36% of the tantalum forms a single mineral, niobium-tantalite, and the rest are dispersed in rock-forming minerals and other accessory minerals, which indicates that most of the tantalum forms an available independent mineral. The beneficiation test shows that the selectivity of the ore is good, and the recovery rate of tantalum and niobium reaches 63.8%～70.8%. This is higher than the beneficiation recovery rate of the currently developed granite-type tantalum mines in China. Therefore, from the aspect of material composition of the deposit, it undoubtedly has development and utilization value.
At present, the main problem is that, since the deposit is a concealed mine with an average depth of 400m, the mining cost is much higher than that of open pit mining, and whether the mine production will have economic benefits in the future is the most concerned issue for investors. Therefore, a detailed development feasibility study must be carried out.
