Light rare earth and heavy rare earth
·Light rare earth
·Lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium.
·Heavy rare earth
·Terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium.
·According to mineral characteristics, it can be divided into cerium group and yttrium group
·Cerium group (light rare earth)
·Lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium.
·Yttrium group (heavy rare earth)
·Gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium.
Common rare earth elements
·Common rare earths are divided into: monazite, bastnaesite, yttrium phosphate, leaching type ore, and lanthanum vanadium limonite.
Monazite
·Monazite, also known as phosphocerium lanthanide ore, occurs in granite and granite pegmatite; Rare metal carbonate rock; In quartzite and quartzite; In Yunxia syenite, feldspar aegirite, and alkaline syenite pegmatite; Alpine type veins; In mixed rock and weathered crust and sand ore. Due to the fact that the main resource of monazite with economic mining value is alluvial or coastal sand deposits, it is mainly distributed along the coasts of Australia, Brazil, and India. In addition, Sri Lanka, Madagascar, South Africa, Malaysia, China, Thailand, South Korea, North Korea and other places all contain heavy placer deposits of monazite, mainly used for extracting rare earth elements. In recent years, monazite production has shown a downward trend, mainly due to the radioactive thorium element in its ore, which is harmful to the environment.
Chemical composition and properties: (Ce, La, Y, Th) [PO4]. The composition varies greatly. The content of rare earth oxides in mineral composition can reach 50-68%. The isomorphic mixtures include Y, Th, Ca, [SiO4], and [SO4].
Monazite is soluble in H3PO4, HClO4, and H2SO4.
·Crystal structure and morphology: monoclinic crystal system, rhombic columnar crystal type. The crystal forms a plate-like shape, and the crystal surface often has stripes or columnar, conical, or granular shapes.
·Physical properties: It is yellow brown, brown, red, and occasionally green in color. Semi transparent to transparent. Stripes are white or light red yellow. Has a strong glass luster. Hardness 5.0-5.5. Embrittlement. The specific gravity ranges from 4.9 to 5.5. Moderately weak electromagnetic properties. Emitting green light under X-rays. Does not emit light under cathode rays.
Yttrium phosphate ore
·Phosphorus yttrium ore is mainly produced in granite, granite pegmatite, and also in alkaline granite and related mineral deposits. It is also produced in placers. Usage: Used as a mineral raw material for extracting rare earth elements when enriched in large quantities.
·Chemical composition and properties: Y [PO4]. The composition consists of Y2O3 61.4% and P2O5 38.6%. There is a mixture of yttrium group rare earth elements, mainly ytterbium, erbium, dysprosium, and gadolinium. Elements such as zirconium, uranium, and thorium still replace yttrium, while silicon also replaces phosphorus. Generally speaking, the content of uranium in phosphorus yttriumore is greater than that of thorium. The chemical properties of yttrium phosphate ore are stable. Crystal structure and morphology: tetragonal crystal system, complex tetragonal biconical crystal type, in granular and block form.
Physical properties: yellow, reddish brown, sometimes yellow green, also brown or light brown. The stripes are light brown in color. Glass luster, grease luster. Hardness 4-5, specific gravity 4.4-5.1, with weak polychromism and radioactivity.
Lanthanum vanadium epidote
A joint research team from Yamaguchi University, Ehime University, and the University of Tokyo in Japan has released a communique stating that they have discovered a new type of mineral containing rare earths in Sanchong Prefecture. Rare earth elements play a crucial role in transforming traditional industries and developing high-tech fields. The new mineral was discovered in the mountains of Ise City, Sanchong Prefecture in April 2011, and is a special type of brown epidote containing rare earth lanthanum and rare metal vanadium. On March 1, 2013, this mineral was recognized as a new mineral by the International Association of Mineralogy and named “lanthanum vanadium limonite”.
Characteristics of rare earth minerals and ore morphology
General characteristics of rare earth minerals
1、 The lack of sulfides and sulfates (only a few others) indicates that rare earth elements have oxygen affinity
2、 Rare earth silicates are mainly island like, without layered, framework like, or chain like structures;
3、 Some rare earth minerals (especially complex oxides and silicates) exhibit amorphous states;
4、 The distribution of rare earth minerals is mainly composed of silicates and oxides in magmatic rocks and pegmatites, while fluorocarbonates and phosphates are mainly present in hydrothermal and weathered crust deposits; Most of the minerals rich in yttrium are present in granite like rocks and related pegmatites, gas-formed hydrothermal deposits, and hydrothermal deposits;
5、 Rare earth elements often coexist in the same mineral due to their similar atomic structure, chemical and crystal chemical properties. That is, cerium and yttrium rare earth elements often coexist in the same mineral, but these elements do not coexist in equal quantities. Some minerals are mainly composed of cerium rare earth elements, while others are mainly composed of yttrium.
The occurrence state of rare earth elements in minerals
In nature, rare earth elements are mainly enriched in granite, alkaline rocks, alkaline ultrabasic rocks, and related mineral deposits. There are three main states of occurrence of rare earth elements in minerals according to mineral crystal chemical analysis.
(1) Rare earth elements participate in the lattice of minerals and form an essential component of minerals. This type of mineral is commonly referred to as rare earth minerals. Monazite (REPO4) and bastnaesite ([La, Ce] FCO3) all belong to this category.
(2) Rare earth elements are dispersed in minerals in the form of isomorphic substitution of elements such as Ca, Sr, Ba, Mn, Zr, etc. This type of mineral is abundant in nature, but the rare earth content in most minerals is relatively low. contain Rare earth fluorite and apatite belong to this category.
(3) Rare earth elements exist on the surface or between particles of certain minerals in an ionic adsorption state. This type of mineral belongs to the weathering crust leaching type mineral, and rare earth ions are adsorbed on which mineral and the parent rock of the mineral before weathering
Regarding. The average content of rare earth elements in the crust is 165.35 × 10-6 (Li Tong, 1976). In nature, rare earth elements mainly exist in the form of single minerals, and rare earth minerals and minerals containing rare earth elements that have been discovered in the world
There are over 250 types of substances, including rare earth content Σ There are 50-65 types of rare earth minerals with REE>5.8%, which can be considered as independent rare earth minerals. The important rare earth minerals are mainly fluorocarbonate and phosphate.
Among more than 250 types of rare earth minerals and minerals containing rare earth elements that have been discovered, there are only over 10 industrial minerals suitable for current metallurgical conditions.
Post time: Nov-03-2023