China clay occurs in the deposits in the form of china clay rock, a mixture of up to 15 per cent china clay and up to 10 per cent mica, and the remainder being quartz.
One of the purest of the clays, composed chiefly of the mineral kaolinite usually formed when granite is changed by hydrothermal metamorphism. Usage of the terms china clay and kaolin is not well defined; sometimes they are used synonymously for a group of similar clays, and sometimes kaolin refers to those obtained in the United States and china clay to those that are imported. Some authorities term as china clays the more plastic of the kaolins. China clays have long been used in the ceramic industry, especially in fine porcelains, because they can be easily molded, have a fine texture, and are white when fired.
China clay mining is a complicated process which can be split into three distinct sections - opencast mining, refining and drying Known as pit operations, this process firstly requires the removal of ground overlying the clay. This is known as overburden, which can vary in depth between one and fifteen metres. Once the clay is exposed, the method of mining is best described as a hydraulic mining process. This means, quite simply, that a jet of water under enormous pressure is fired at the pit face from a water cannon known in the industry as a monitor. This liberates from the quarry face the china clay, together with sand and mica. The material runs in slurry form to the lowest part of the pit, known as the sink, where it is lifted by centrifugal pumps to mechanical sand classifiers, where the more coarse sand elements are removed. The sand is disposed of on belt conveyors, which deposit it on low profile tips that can then be landscaped and seeded with grass. Having removed the coarsest of the sand, the clay suspension is then transported by underground pipeline to the second process: refining.
Silicon dioxide SiO2. Quartz is the most abundant and most common mineral on the Earth. It is found in almost every geological environment and also it is at least a component of almost every rock type. It has a hexagonal crystal structure and is made of trigonal crystallized silica. It is most varied in terms of varieties, colors and forms. The most important distinction between the types of quartz is that one is of macrocrystalline, which is individual crystal visible to the unaided eye, and the other is microcrystalline or cryptodrystalline varieties, aggregates of crysstals visible only under high magnification. Chalcedony is the generic term for cryptocrystalline quartz. The transparent variety tends to be macrocrystalline and the cryptocrystalline varieties are either translucent or mostly opaque.
Drilling fluids consume some 85% of the world's total barytes consumption, making them easily the largest market.
Barium Sulfate BaSO4 Drilling fluids consume some 85% of the world's total barytes consumption, making them easily the largest market.
Barite, barytes, or heavy spar, a white, yellow, blue, red, or colorless mineral. It is a sulfate of barium, BaSO4, found in nature as tabular crystals or in granular or massive form and has a high specific gravity. The mineral is widely distributed throughout the world. It often occurs in veins with lead and zinc minerals. It is insoluble in water, and this property is made use of in testing for the sulfate radical. It is practically insoluble under ordinary conditions in all the usual chemical reagents. Barite is used as a commercial source of barium and many of its compounds. Ground barite is used as a filler in the manufacture of linoleum, oilcloth, paper and textile manufacturing, rubber, and plastics. Finely ground barite is used to make a thixotropic mud for sealing oil wells during drilling. Prime white, a bleached barite, is used as a pigment in white paint but is not as satisfactory as blanc fixe, a chemically precipitated barium sulfate, or lithopone, a mixture of barium sulfate, zinc sulfide, and zinc oxide. Barites is a material with environmental protecting function, it has a lot of advantages, such as a strong inertia, good stability, acid and alkali proof, moderate rigidity, high specific gravity, high whiteness, absorb in harmful radial. So, it is widely used in the fields of all kinds of dope, middle and high-grade paint, engineering plastic, medicine compounding chemical industry, rubber, paper-making, pottery, cosmetic etc.
KAlSi3O8 - Orthoclase
KAlSi3O8 - Microcline
NaAlSi3O8 - CaAl2Si2O8 - Plagioclase
In the manufacture of high-class, colourless glass, feldspar should have a maximum of 0.1% Fe2O3 though upto 0.3% is permissible.
The History Says
The word comes from the German "feldt spat", meaning "field spar", "spar" meaning common clevable material - the material dredged up on farm lands during plowing. Most of them are not affected by acid (exception the Ca rich plagioclase - Anorthite). Orthoclase got is name from the Greek phrase meaning "straight fracture", Microcline from a Greek phrase meaning "small incline", and Plagioclase from the Greek phrase meaning "oblique fracture".
The Present Scenario
Feldspar is used as bonding agent along with magnesium oxide, magnesium chloride and other synthetic glue in the manufacture of abrasives, wheels, discs and other shapes.
FELDSPAR comprises a group of minerals containing potassium, sodium, calcium and aluminium silicates. They are the most common rock-forming minerals. The common feldspar is potassium feldspar, namely, orthoclase (K2O, Al2O3, 6SiO2). Sodium feldspar is albite (Na2O, Al2O3, 6SiO2) and calcium feldspar is anorthite (CaO, Al2O3, 2SiO2). A variety of crossed, hatched, twinned orthoclase (to be seen under the petrological microscope only) is called microcline. Sodium and calcium feldspars form an somorphous mixture known as plagioclase feldspars.
In between sodium and calcium, the other feldspars of the plagioclase series are oligoclase, andesine, labradorite and bytownite. They are composed of suitable proportions of sodium and calcium with an increasing percentage of calcium begining from mineral oligoclase to bytownite, turning completely into calcium feldspar (anorthite). A rock containing only plagioclase feldspars is called anorthosite.
The commercial feldspar is orthoclase. The potassium molecule is replaced by sodium to some extent and hence, orthoclase feldspar usually contains a small percentage of sodium. The composition range of the commercial feldspar varies within the limits of potash, soda and upto oligoclase.
Potash and soda feldspar occur as essential constituents of granite, syenite and gneisses. However, workable deposits are found in pegmatite veins consisting mainly of feldspar, quartz-feldspar veins and also occur with mica pegmatites. Feldspar is of widespread occurrence and is mined in almost all countries.
Perlite is an amorphous volcanic glass which has a relatively high water content and occurs naturally. It has one of the most unusual property, i.e. it greatly expands when sufficiently heated.
Properties and Uses of Perlite
Perlite becomes soft, as it is a glass, at a temperature of 850-900°C. The trapped water in the structure of perlite escapes and makes the material to expand 7 - 15 times of its original volume. The expanded material is brilliant white in color because of the reflectivity of the trapped bubbles.
The density of raw perlite or the unexpanded perlite is around 1100 kg/m3 (1.1 g/cm3). The density of typically expanded perlite is 30 - 150 kg/m3.
Since perlite has low density and is relatively economical, it is used commercially in following ways:
Construction and manufacturing fields.
Lightweight plasters and mortars, insulation, ceiling tiles and filter aids.
In horticulture, it makes composts more open to air, while having still a good water-retention properties.
It makes a good medium for hydroponics.
It is also used in foundries and cryogenic insulations.
Analysis of Perlite
70-75% silicon dioxide: SiO2
12-15% aluminum oxide: Al2O3
3-4% sodium oxide: Na2O
3-5% potassium oxide: K2O
0.5-2% iron oxide: Fe2O3
0.2-0.7% magnesium oxide: MgO
0.5-1.5% calcium oxide: CaO
3-5% loss on ignition (chemical / combined water)
Attapulgite clay A fibrous claylike material, essentially ((OH 2 ) 4 Mg 5 Si 8 O 20 (OH) 2 -- 4H 2 O), rich in magnesium, and used as a filling material in papermaking, usually in coatings for reproduction papers. The clay is also called "fuller's earth," from its ability to remove dirt and grease from wool, a process called "fulling."
a) Attapulgite is a naturally mined clay. It is a needle-like clay mineral composed of magnesium-aluminum silicate. Major deposits occur naturally in Georgia, USA. Attapulgite and sepiolite have similar structures and both can be used in salt-water mud to provide low-shear rate viscosity for lifting cuttings out of the annulus and for barite suspension. Attapulgite and sepiolite are sometimes called "salt gel." Attapulgite has no capability to control the filtration properties of the mud. For use as an oil-mud additive, the clay is coated with quaternary amine, which makes it oil-dispersible and provides gel structure but does not improve the filter cake, unlike organophilic bentonite clay. b) Attapulgite is a kind of crystalloid hydrous magnesium-aluminum silicate mineral, having a special laminated chain structure in which there is a crystalline lattice displacement existed. Thus it makes the crystals contain uncertain quantities of Na+, Ca+, Fe3+ and Al, and present in the shape of needles, fibers or fibrous clusters. Attapulgite has very good colloidal properties such as: specific features in dispersion, high temperature endurance, salt and alkali resistance, and also high adsorbing and de-coloring capabilities. Furthermore, attapulgite has certain plastic and adhesive characters. Its ideal molecular formula is: c) The attapulgite structure is somewhat between laminated and chain structure. Attapulgite looks like soil, and compact blocks which are found in the sedimentary rocks and the weathering crust. Attapulgite are white, hoar, caesious or celadon, or with some dim mercerization in color. The clay of attapulgite is fine and a bit greasy smooth, light in weight, crispy, and the fractured surface is like shells or in irregular shapes. Attapulgite has strong ability to absorb water. When it is wet, attapulgite shows plastic and adhesive properties; and when it gets dry, attapulgite does not shrink much and does not show cracks. When it is soaked in water, attapulgite collapses. The suspending liquid does not create soliquids and precipitates, when meeting electrolytes.
Attapulgite is a kind of crystalloid hydrous magnesium-aluminum silicate mineral, having a special laminated chain structure in which there is a crystalline lattice displacement existed. Thus it makes the crystals contain uncertain quantities of Na+, Ca+, Fe3+ and Al, and present in the shape of needles, fibers or fibrous clusters. Attapulgite has very good colloidal properties such as: specific features in dispersion, high temperature endurance, salt and alkali resistance, and also high adsorbing and de-coloring capabilities. Furthermore, attapulgite has certain plastic and adhesive characters. Its ideal molecular formula is: Mg5Si8O20(HO)2(OH2)4•4H2O. The structure is somewhat between laminated and chain structure. Attapulgite looks like soil, and compact blocks which are found in the sedimentary rocks and the weathering crust. Attapulgite are white, hoar, caesious or celadon, or with some dim mercerization in color. The clay of attapulgite is fine and a bit greasy smooth, light in weight, crispy, and the fractured surface is like shells or in irregular shapes. Attapulgite has strong ability to absorb water. When it is wet, attapulgite shows plastic and adhesive properties; and when it gets dry,attapulgite does not shrink much and does not show cracks. When it is soaked in water,attapulgite collapses. The suspending liquid does not create soliquids and precipitates, when meeting electrolytes. Attapulgite clay mineral resources distribute in only several countries in the world at the present. Attapulgite reserve capacity of Xuyi contains the 70% in China, and 35% in the world. Compared to the largest commercial attapulgite deposits in the United States, Xuyi attapulgite products have the following special features: Because the geological conditions under which Chinese attapulgite was deposited are different from that of the USA attapulgite deposits, our attapulgite products have very low grit (percentage retained on a 325 mesh wet screen), low free silica content, and low carbonate content. Selectively mined and processed attapulgite products have a very high dispersion viscosity and API yield. The products processed from naturally occurring mixtures of attapulgite show especially high dispersion viscosity, high API yield, and extremely low grit.
Chemical Formula: Mg4Si6O15(OH)2·6(H2O)
Composition: Molecular Weight = 613.82 gm
Magnesium 15.84 % Mg 26.26 % MgO
Silicon 27.45 % Si 58.73 % SiO2
Hydrogen 1.97 % H 17.61 % H2O
Oxygen 54.74 % O
100.00 % 102.61 % = TOTAL OXIDE
Empirical Formula: Mg4Si6O15·6(H2O)
Environment: Secondary mineral associated with serpentine. Can precipitate from alkali saline waters in arid environments.