China Clay / Kaolin
Kaolin is a white, soft, plastic clay mainly composed of fine-grained plate-like particles. Kaolin is formed when the
anhydrous aluminium silicates which are found in feldspar rich rocks, like granite, are altered by weathering or hydrothermal
processes. The process which converted the hard granite into the soft matrix found in kaolin pits is known as “kaolinisation”.
The quartz and mica of the granite remain relatively unchanged whilst the feldspar is transformed into Kaolinite.
It is a layered silicate mineral, with one tetrahedral sheet linked through oxygen atoms to one octahedral sheet of alumina
octahedra. Rocks that are rich in Kaolinite are known as kaolin or china clay. Kaolinite is a mineral belonging to the group of
alumino-silicates. It is commonly referred to as “China Clay” because it was first discovered at Kao-Lin, in China. The term
kaolin is used to describe a group of relatively common clay minerals dominated by Kaolinite and derived primarily from the
alteration of alkali feldspar and micas.
China clay is an industrial mineral used primarily as an inert filler and it is combine with other raw materials in a wide variety
of applications. Kaolin is a white, soft, plastic clay mainly composed of fine-grained plate-like particles. Kaolin is formed
when the anhydrous aluminium silicates which are found in feldspar rich rocks, like granite, are altered by weathering or
The quartz and mica of the granite remain relatively unchanged whilst the feldspar is transformed into Kaolinite. The refining
and processing of the fine fraction of the kaolinised granite yields predominantly Kaolinite with minor amounts of mica,
feldspar, traces of quartz and, depending on the origin, organic substances and/or heavy minerals. Individual kaolins vary in
many physical aspects, which in turn influence their end use. Of particular commercial interest is the degree of crystallinity
which influences the brightness, whiteness, opacity, gloss, film strength, and viscosity.
China Clay is a hydrated Aluminium silicate, part of the group of industrial minerals, with the chemical formula
Kaolin is very soft mineral (occupying place 2-2.5 in the Mohs hardness scale).
Synonyms of China Clay includes Kaolin, Levigated china clay, Kaolinite, Metakaolin, Ball clay, etc.
China Clay / Kaolin properties:Kaolinite has a low shrink–swell capacity and it is a soft, earthy, usually white mineral, produced by the chemical weathering
of aluminium silicate minerals like feldspar. In many parts of the world, it is colored pink-orange-red by iron oxide, giving it a
distinct rust hue. Lighter concentrations yield white, yellow or light orange colors. Commercial grades of kaolin are supplied
and transported as dry powder, semi-dry noodle or as liquid slurry. This makes it a very essential mineral in our day-to-day
Kaolin is part of our natural world. Its uses are multiple and diversified. Kaolin’s whiteness and plasticity make it extremely
suitable for its extensive use as a filler, extender, ceramic raw material and pigment. It is also an important raw material to
refractories, and to catalyst, cement and fiber glass industries.
Kaolin is used in many applications. It is a unique industrial mineral, which remains chemically inert over a relatively wide
pH range and it offers excellent covering when used as a pigment or extender in coated films and filling applications. In
addition, it is soft and non-abrasive and has a low conductivity of heat and electricity. The two largest applications of
kaolin are the coating of paper to hide the pulp strands and the production of high grade ceramic products.
The largest use is in the production of paper, including ensuring the gloss on some grades of paper. It is also used in paint,
rubber, detergents & textile industries.
China Clay / Kaolin is used (or was used in the past):
- In ceramics (it is generally the main component in porcelain)
- In toothpaste
- As a light diffusing material in white incandescent light bulbs
- In cosmetics
- As paint to extend titanium dioxide (TiO2) and modify gloss levels
- For its semi-reinforcing properties in rubber
- In adhesives to modify rheology
- In the production of common smoking pipes in Europe and Asia
- In organic farming, as a spray applied to crops to deter insect damage, and in the case of apples, to prevent sun scald
- As whitewash in traditional stone masonry homes in Nepal (the most common method is to paint the upper part with white kaolin clay and the middle with red clay; the red clay may extend to the bottom, or the bottom may be painted black)
- As a filler in Edison Diamond Discs
- As an indicator in radiological dating since kaolinite can contain very small traces of uranium and thorium
- To soothe an upset stomach, similar to the way parrots (and later, humans) in South America originally used it (more recently, industrially-produced Kaolinite preparations were common for treatment of diarrhea
- For facial masks or soap
- As adsorbents in water and wastewater treatment.
China Clay Chemical Properties/Composition :
China Clay Physical Properties :
|Appearance||: White fine powder|
|Sp. gravity||: 2.5 – 2.7|
|Oil absorption||: 25 to 35|
|PH of 10% aqueous solution||: 7 to 8|
|Water Soluble salts||: max 1.0%|
|Volatile matter||: max 1.0%|
|Loss on Ignition||: 13 to 15%|
China Clay Industrial Applications & Uses :
China Clay is the heart of several Industries like paper, potteries, tiles, ceramics, glass & paints. ‘
|1. China clay in Paints||:||It is used in various paints like distempers, cement primer, wood primer, texture paint, spray plaster, putties, fillers & undercoats. In its hydrous or calcined forms, kaolin can improve the optical, mechanical and rheological properties of a paint. Calcined kaolin is widely used in satin and matt paints where they can deliver increased opacity, whiteness and scrub resistance. Kaolin is particularly useful as a partial replacement for TiO2 pigment.
|2. China clay in Plastic :||It is used as a filler in combination with others to impart strength & smoothness in plastic Industry. Kaolin is used in plastics to provide smooth surfaces, dimensional stability and resistance to chemical attack, to conceal fibre reinforcement patterns and to reduce shrinkage and cracking during polymer compounding and shape forming. It is also used as a rheological modifier and a functional filler, in which capacity it is used to improve mechanical, electrical and thermal properties.
A major application is in PVC cables where its main function is to improve electrical properties. Other important applications include specialty films where they impart anti-blocking or infrared absorption characteristics. Chemically treated, calcined kaolin is one of the major additives used in the manufacture of automotive parts based on engineering thermoplastics.
||It is used in variety of papers, cardboards, hard boards and others. In this industry, kaolin is used both as a filler in the bulk of the paper and to coat its surface. Kaolin’s whiteness, opacity, large surface area and low abrasivity make it an ideal raw material for paper production. Its use allows a reduction in the amount of expensive wood pulp required, enhances the optical properties of the paper and improves its printing characteristics.
When used as a coating on the surface of the paper, kaolin’s whiteness improves paper brightness and opacity, whilst the size and the shape of the individual kaolin particles give the gloss and printed paper quality required for many different kinds of paper. Examples include papers for magazines and brochures, art paper, cartons and boxes etc.
||Kaolin converts to mullite and glass when fired to temperatures exceeding 1000° C. It is used in formulations described as white-wares, which consists of tableware, sanitaryware, and wall and floor tiles.
It provides strength and plasticity in the shaping of these products and reduces the amount of pyroplastic deformation in the process of firing. In tableware, in addition to the strength and plastic qualities, it is essential to the achievement of high fired whiteness. This is because it contains a low content of coloring elements such as iron and titanium. For sanitaryware, the product is formed by casting (either in plaster, or resin moulds under pressure).
Kaolin contributes the rheological properties that enables the casting slip to flow and drain after the cast formation. The cast pieces are relatively heavy and the kaolin must be strong to withstand the weight and retain the shape before the pieces enter the kiln. Fillers: When kaolin is used as a pigment, it is divided broadly into filler- and paper coating grade clays based on their brightness and viscosity.
Its main properties, especially its whiteness or near whiteness, make it very suitable as a filler or pigment. In addition, it remains inert over a wide PH range, is nonabrasive, has a low heat and electrical conductivity and offers brightness and opacity.
||It is used for Electrical insulation, High voltage insulation components, electrical wires, EPDN rubber and others.
|6. China clay in Cosmetic & Soap :||China Clay is used in toothpaste, cosmetic and soap industry. It can also be used as an excipients in personal care products including, for example, in body therapy (bath and skin treatments) and in cosmetics.
||Refractories are produced from natural materials, combinations of compounds and minerals, such as kaolin, which are used to build structures subjected to high temperatures, ranging from simple to sophisticated products, e.g. from fireplace brick linings to re-entry heat shields for the space shuttle. In industry, they are used to line boilers and furnaces of all types reactors, ladles, stills, kilns and so forth.
||The fibreglass which is used as a strengthener in a multitude of applications requires the use of kaolin for its manufacture. Kaolin allows for the strengthening of the fibres integrated into the material. It also improves the integration of fibres in products requiring strengthened plastics: cars, boats and marine products, sporting goods and recreation products, aviation and aerospace products, circuit board manufacturing, fibreglass insulation, fibreglass air filters, fibreglass tanks and pipes, corrosion resistant fibreglass products, fibreglass building and construction products, etc.|
We ensure the highest grade & uniform particle size product for the industries like Plastics & paints.
China Clay Price in India (Our suggested China Clay grades):
|Kaolin Grades / Model no.||VK – 89P300||VK – 92W300||VK – 90N300||VK – 89PL||VK – 92NL|
|Product Name||Levigated China Clay powder||Water washed China Clay powder||Natural China Clay / Kaolin powder||Water washed China Clay Lumps||Natural China Clay / Kaolin Lumps|
|Whiteness (%)||90% – 92%||90% – 92%||88% – 90%||90%||88%|
|Moisture (%)||< 0.5||<0.5||<0.5||< 0.5||<0.5|
|SiO2 (%)||47 to 48||58 to 59||74 to 75||47 to 48||74 to 75|
|Al2O3 (%)||37 to 39||26 to 27||16 to 17||37 to 39||16 to 17|
|K2O (%)||3 to 3.2||0.5 to 1||0.5 to 1||3 to 3.2||0.5 to 1|
|Na2O (%)||0.5 to 1||0.5 to 1||1 to 2||0.5 to 1||1 to 2|
|CaO (%)||0.1 to 0.2||0.5 to 1||0.5 to 1||0.1 to 0.2||0.5 to 1|
|MgO (%)||0.2 to 0.3||0.4 to 0.5||0.3 to 0.4||0.2 to 0.3||0.3 to 0.4|
|LOI (%)||9 to 10||11 to 12||5 to 6||9 to 10||5 to 6|
|Particle Size||300 mesh||300 mesh||300 mesh||Lumps||Lumps|
|Top cut (micron)||50 micron||50 micron||50 micron||-||-|
|Applications||Paints; Plastics; Paper & cosmetics industry||Paints; Plastics; Paper & cosmetics industry||Ceramic industry; rubber industry and many other uses||Paints; Plastics; Paper & cosmetics industry||Ceramic industry; rubber industry and many other uses|
Apart from above grades we develop tailor made Kaolin to meet the specific requirement of our clients. Our R&D; is also working on ultra-fine China Clay powders.
|Packaging & Delivery Details:|
|Packaging:||50 kg pp bag; 1ton/bag; 1*20 container, can load 25-27 MT or upon clients’ requirement|
|Delivery:||within 5 – 20 days (depending upon the delivery location) after receiving the deposit|