Spodumene, monoclinic, crystal often columnar, granular or plate-like. The color is gray, grayish green, purple or yellow, etc., hardness 6.5-7, density 3.03-3.22g/cm3. As a raw material for lithium chemical products, it is widely used in the lithium chemical, glass and ceramic industries, and enjoys the reputation of “industrial MSGâ€.
Chinese name: spodumene foreign name: spodumene hardness: 6.5-7
Crystal: columnar, granular or plate color: gray, grayish green, purple or yellow luster: glass luster
1. What is spodumene?
The lithium spodumene is called spodumene, and its content is LiAl(SiO3)2 or Li2O·Al2O3·4SiO2. The theoretical lithium content is 3.75% (lithium oxide 8.04%).
Spodumene is one of the main lithium-containing minerals, also known as type 2 spodumene. Monoclinic crystals, often in the form of columns, granules or plates. The color is gray, grayish green, emerald green, purple or yellow. The glass is shiny and the streaks are colorless. The hardness is 6.5 to 7, and the density is 3.03 to 3.22 g/cm3. The spodumene is mainly produced in the palladium-rich pegmatite. The symbiotic minerals are quartz, albite, and micro-plagioclase. Crystals change color when heated or exposed to ultraviolet light, and they lose their luster under the influence of sunlight. When calcined to about 1000 ° C, it rapidly transforms into β-type spodumene and has thermal cracking properties.
Spodumene is classified into three categories according to its use, chemical composition and smelting process requirements: spodumene for chemical use, spodumene for ceramics, and low-iron spodumene.
Second, the role of spodumene
1. Application of spodumene in porcelain brick
As a non-glazed low porosity product, “Qualified Brick†has quite good mechanical properties such as impact, hardness and durability. It is the preferred object for the tile series. Porcelain tiles differ from glazed tiles and sanitary wares in that they can be used directly in the body to reduce the firing temperature.
Recent studies have found the advantage of replacing some nepheline syenite with spodumene.
In the 1990s, Italian experts studied that the addition of spodumene to ceramic tiles would achieve an increase in vitrification in the production process and a reduction in line shrinkage during the sintering process to reduce product dimensional deviation. In the sense of anti-fouling, the surface quality of the floor tiles is improved and the mechanical strength is enhanced.
2. The role of spodumene in the formulation of vitrified ceramic tile (VHT)
Fully vitrified, unglazed polished tiles require a firing temperature of approximately 1200 ° C and a sintering time of 45 minutes. Due to such a short period of time, conventional fluxes appear to be ineffective, and the use of spodumene will contribute to melting and material densification.
Recently, Southeast Asian countries have made a series of industrial appraisals to verify the above conclusions. Nowadays, some manufacturers in China replace x-type feldspar with xanthanite, which accounts for 10% of the weight of the body. The results are as follows: the productivity is shortened due to shortening the firing cycle, and the firing temperature is lowered by 25 ° C. The color pollution resistance of the green body is improved by 90%, the mechanical strength is enhanced, and the color is more "three-dimensional".
3. Application of spodumene in wall and floor glaze
Adding 2~12% spodumene to the glaze (or frit) formula, instead of the corresponding raw materials such as feldspar, can play the following roles:
1. Reduce the firing temperature (fluxing), save energy and extend furnace age;
2. Reduce the melt viscosity, improve the high temperature fluidity and vitrification, improve the anti-pollution ability, and enhance the glaze strength and smoothness;
3. Reduce the thermal expansion coefficient, overcome the glaze crack and improve the thermal stability;
4. Improve whiteness and enhance gloss;
5. Improve chemical stability and acid resistance.
Third, the spodumene identification characteristics
Color: pink, purple, yellow, green.
Polychromaticity: The three colors are obvious.
Hardness: 6.5-7 (more rigid).
RI: 1.66-1.68DR0.015 two axes (+).
SG: 3.18 in 3.05 heavy liquid, 3.32 heavy liquid.
Inclusions: crystal inclusions, visible puddles due to cleavage and development, stepped at the break, if there are cracks, they can be seen in parallel.
English name spodumene monoclinic pyroxene minerals. The chemical formula LiAl[Si2O6] often has traces of sodium, calcium, magnesium, and occasionally chromium, rare earth, strontium and barium. The crystal has a short column or plate shape, and the erect crystal face has a crystal face stripe. Sometimes there are huge crystals, which have been reported to be 16 meters long. The aggregate is in the form of a rod and a dense cryptocrystalline block. White, light green, green, yellow green, yellow brown, pink, purple, blue green, blue and other colors. Transparent - slightly transparent. Glass luster, cleavage surface microstrip pearly color. Two-axis crystal, +2v=50o~70o.
The refractive index ng=1.665 to 1.682, nm=1.660 to 1.671, np=1.651 to 1.670, and the birefringence ratio is 0.012 to 0.025. The pleochroism is remarkable, and the pink crystals are: none-light green-light purple-purple-violet; green crystal: colorless-light green-blue-green-green. The dispersion is 0.017. Under ultraviolet light, purple has pink-orange fluorescence; yellow-green has orange-yellow fluorescence; emerald spodumene has no fluorescence, but has orange phosphorescence under x-ray. Hardness 6 to 7. The relative density is 3.184-0.03. The pyroxene type cleavage is complete or medium, with cracks along the edges. Fractures are sparse-lobed. Unlike other pyroxene minerals, spodumene is a pegmatite mineral produced in granitic pegmatites, often associated with crystal, tourmaline, and beryl.
Fourth, spodumene origin
Famous places of origin are California, Brazil, Minas Gerais, Madagascar, Pakistan, Myanmar, Xinjiang, China and other places. The most important gemstone mineral in the pyroxene group. In addition, it is also used as a raw material for lithium smelting in industry. Purple spodumene, which contains lavender like lavender because it contains manganese, was discovered by Dr. Consay in 1902.
Kunzite is a kind of pyroxene. It is prolific in granitic pegmatite and sometimes forms coarse crystals. In the Black Hills of the United States, a huge spodumene of 14.3 meters was discovered. (Kunzite) crystals. Kunzite is a high-quality mineral source for the extraction of lithium in the industry, but the beautiful and crystal-cleared Kunzite (green diaspora, purple spodumene) is used as a gem material, usually gem-quality. Spodumene can weigh more than 1 carat, and more than 5 carats of spodumene are not uncommon.
At present, more commonly seen on the market is light pink or light purple smectite (Kunzite), and occasionally we can also see the lighter green sapphire (Kunzite), but unfortunately the color is not stable, exposed to strong light or high temperature Underneath, the color will fade very quickly, and this type of smectite (Kunzite) is actually irradiated. The color of natural dark green Kunzite is due to the chromium content, so the color is very stable and the value is relatively high, but it is very rare. It is called Hiddenite in foreign countries.
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