Classification background and overview of lithium ores
Lithium ore is an important and advantageous mineral in Sichuan Province. It not only has concentrated resource production areas, but also the ore is easy to select and suitable for comprehensive utilization. The geological structure of the mining area is simple and the mining technical conditions are good. There are 12 existing mining areas, 2 large deposits, 6 medium-sized deposits and 4 small deposits, with lithium oxide reserves of 1.188 million tons, ranking second in the country; among lithium ores, there are 7 rich ores with lithium oxide grades greater than 1%. , with retained reserves of more than 1 million tons, and rich ore reserves ranking first in the country. Kangding County Jiaka is the main large-scale lithium deposit in Sichuan. The total lithium reserves in the mining area reach 894,400 tons, accounting for 75% of the province’s total reserves, and are accompanied by a variety of beneficial elements such as rubidium, cesium, niobium, tantalum, and zirconium. Sichuan lithium ores contain high lithium oxide (containing more than 1.2% Li2O) and many associated beneficial elements (niobium, tantalum, beryllium, tin). Most of the lithium recovery rates are around 90%, but the comprehensive utilization of associated elements is poor. Most of Sichuan’s lithium mines are located in alpine areas where transportation and electricity are difficult and the economy and technology are backward, which restricts the large-scale utilization of resources. At present, the lithium pyridine ore resources in Sichuan Province are only exploited on a small scale, with an annual ore processing capacity of 100,000 tons and an annual output of 20,000 tons of spodumene concentrate.
Classified resource distribution of lithium mines
Global lithium resources are not scarce, and lithium deposits have been discovered in at least 20 countries, including Chile, Bolivia, China, Australia, the United States, Brazil, Portugal, Argentina, Russia, Zimbabwe, the Democratic Republic of the Congo, Serbia, Spain, Austria, Israel, Ireland, France, India, South Africa, Finland, Sweden, Mozambique, etc. Among them, the countries with the richest lithium resources are Chile, Bolivia, China, Australia, etc. It can be said that for now, brine-type and pegmatite-type lithium ores are still the main body, and new types of lithium ores such as sedimentary types account for a very small proportion. Moreover, the progress of lithium ore exploration worldwide is quietly affecting the world. Lithium mine pattern.
Main types of lithium ore classification and prospecting progress
So far, there are three main types of lithium deposits discovered in nature: brine type, pegmatite type and sedimentary rock type. According to statistics from Paul Gruber and Pablo Medina of the University of Michigan, lithium-containing brine deposits account for 66% of global lithium resources, pegmatite deposits account for 26%, and sedimentary rock deposits account for 8%. In addition, clay type (containing lithium in clay deposits) and lacustrine evaporite type (containing lithium in lacustrine evaporite) also have potential development significance.
1. Brine type lithium ore
Brine-type lithium ores are an important type of lithium deposits and the main source of lithium. They are mainly distributed in Bolivia, Chile and Argentina in South America, known as the “Lithium Triangle”. Since the 1980s, the huge lithium resources in salt lake brine have been developed and utilized. Lithium extraction from brine has become the dominant force in the world’s lithium industry. In 1995, the global lithium extraction from brine accounted for only 26% of the total lithium production capacity. By 2003, the world’s lithium The proportion of lithium extracted from brine in production has increased to 91.2%. The main cause mechanism is that in closed basins, especially closed basins in arid desert areas, lithium can be enriched in underground brine and form lithium deposits with mining value.
In the highland desert area of western South America, the world-famous giant lithium deposits of the Salarde Uyuni in Bolivia and the Salarde Atacama in Chile have been identified. The former’s mineralization era was the Cretaceous. To the Paleogene-Neogene, the latter belongs to the Quaternary.
2. Pegmatite-type lithium deposit
This type of deposit is widely distributed and mainly occurs in relatively stable geological structural units such as ancient crystalline shields and blocks. The mineralization era is mainly the Precambrian battery-grade lithium carbonate, and a few were formed in the early Paleozoic. Ore-bearing pegmatites can be divided into two categories: pegmatites with banded structures and pegmatites without banded structures.
(1) Banded structure pegmatite lithium deposit. The mineral composition of this type of deposit is complex. In addition to containing a large amount of spodumene, lucite, lepidolite, eucryptite and lithium aluminite, it often also contains a small amount of beryl and columbite that can be comprehensively utilized. , cassiterite, cosmonite garnet and other rare metal minerals. The spodumene content in this type of deposit is about 20%. The crystals are coarse and the maximum length can exceed 14m. They are currently the main source of high-quality low-iron spodumene concentrate (such as the Greenbushes Lithium Mine in Australia).
(2) Pegmatite deposits without banded structures. The pegmatite body of this type of deposit is basically a single-phase homogeneous rock body, composed of albite, microcline, quartz, muscovite and spodumene. A small amount of minerals include beryl, cassiterite and tantalum-niobium minerals. Spodumene is evenly distributed, and its content can account for 25% of the total rock mass. It is an important source of pegmatite-type spodumene. Such lithium deposits are usually either stand-alone lithium deposits or lithium deposits with small amounts of beryllium and tantalum. The Kings Mountain deposit and the Bessemer City deposit in the “cassiterite-spodumene” belt in North Carolina, USA, can be used as typical representatives.
3. Sedimentary lithium deposit
In a broad sense, sedimentary lithium deposits generally refer to lithium deposits produced in sedimentary rocks that do not yet have independent industrial mining but have market competitive value, including bauxite, coal mines, and kaolin deposits that can be used as associated minerals The mineral deposits utilized generally have low content, unclear occurrence status, or often do not have independent minerals but are present in the clay mineral lattice, making it difficult to mine economically.However, due to the very large total amount of its resources, it has attracted great attention, especially for some bulk mineral mining enterprises with low economic benefits. Some have achieved technological breakthroughs and will surely lead the new development of the industry.
4. Clay-type lithium deposit
Lithium-rich clays are mainly clays rich in hectorite, saponite and stinkstone. Huge amounts of lithium resources are known to exist in the hectorite clays of the western United States. In the 1970s, the United States was able to extract 75% of the lithium in ancient weathering crust clay rocks. Clay minerals in the Carboniferous Benxi Formation in the North China coal mine distribution area are also very widely distributed. They are an important refractory raw material base in China. Clay mines, bauxite and their surrounding rocks – clay rocks in Jiaozuo, Henan, Yuncheng, Shanxi and other places It generally contains lithium, and the lithium oxide content far exceeds the lithium requirements for a certain lithium-gallium bauxite deposit in southwest China in the “Mining Industry Requirements Reference Manual”. The resources of such deposits can often reach very large scales and have attracted much attention. For example, on January 6, 2016, Canadian Alix Resources announced that it had discovered a lithium-rich clay layer in Tecolote, Mexico. (Clay-type lithium ore), the estimated resource amount is 43.3 million tons, and the average lithium grade is 0.3005%. The Taklot lithium mineralization area developed in the rhyolitic tuff, ignimbite and volcanic breccia areas from the Oligocene to the Miocene in the Paleogene-Neogene period. The ore body is composed of a series of lithium-containing clay layers. . The lithium-containing mineral in the upper layer is mainly hectorite, and the lithium-containing mineral in the lower layer is polysilicon lepidolite.
