On the surface, it appears to be ordinary. By look alone, kaolin, a platy soft white clay, can conceal its versatility and importance to a wide range of industries. Kaolin comes in various forms, namely kaolin powder, kaolin lump, and kaolin noodle, all of which are processed thoroughly to ensure a high-quality result.
Kaolin, which was found in China, has been used in the production of porcelain and exquisite china for millennia. Kaolin is now a significant and cost-effective pigment in many papers, ceramics, cement, and cosmetic products.
If you’re looking for further information regarding kaolin, its types, and use cases, look no further because here we’ll be looking into everything you need to know about kaolin and more!
Are you ready? Let’s dive in!
What is Kaolin?
Originally, kaolin is produced from Kaolinite, a mineral classified as an alumino-silicate. It is frequently referred to as China clay or 高嶺 (Gāo lǐng) since it was discovered in China. Moreover, kaolin is a term used to describe common clay minerals with a high percentage of kaolinite.
The term “kaolin” comes from the Chinese word for “high ridge“, which alludes to the hill in south-eastern China where the clay was found and initially used. In the 7th and 8th centuries, the Chinese were the first to use kaolin to make porcelain. It took centuries for the technique to be replicated in other areas of the world.
The white tint of the mineral can occur naturally or result from processes that remove minerals and other color-bearing components. The mineral’s tiny particle size adds to its white hue by scattering light.
Kaolin was produced by the modification of alkali feldspar and micas. Because of its whiteness and plasticity, kaolin is widely used across industries, namely a filler grade, raw material and pigment for ceramics, and extenders. It is also utilized as a raw material in the catalyst, refractory, fiberglass, and cement industries. Some even use it for cosmetics and skincare due to its purifying nature! What a multifunctional mineral, right?
Similar to its use, kaolin also comes in a variety of sizes and forms. Three of the most popular ones often used in industries are powder, lump, and noodle. These three differ from one another based on their forms and moisture level. Kaolin lump has the most moisture of all with 33-35% moisture, followed by kaolin noodle with 12-14% moisture content, and the last one is kaolin powder with moisture level as low as 2-4%.
How Kaolin Powder was Made
The powder version of kaolin went through a pretty extensive process before it can be used in industrial processes. Since kaolinite is a type of mineral found in the earth, people must mine it first, usually using water jet mining to extract it from the earth. Afterward, kaolinite goes through a process called centrifuge kaolin slurry. The sand is extracted, and kaolinite can go further to its first filtering process using 100 mesh screens, followed by the second and third ones using 200 and 325 mesh screens.
After being filtered, kaolinite will undergo a high-pressure pump and filter press to purify and solidify its forms. In this stage, you will find kaolin clay or lump with a moisture level of around 33-35%.
However, if you want to get a powdered version of kaolin, you must naturally dry your kaolin lump into a kaolin noodle with approximately 1% moisture level. Afterward, the kaolin noodle will be milled using a disc milling machine into kaolin powder.
Related: All Steps in Kaolin Production – Mining and Processing Explained
How Do People Use Kaolin Powder?
After you know how kaolin powder is created, you might wonder how to use it and what you can make with a heap of its powder.
The short answer is many things. From paper to cosmetics to ceramics, here are some of the most common uses of kaolin powder in the industry.
Kaolin powder is a kind of clay that is also known chemically as hydrated silica-aluminate. When used as a filler in adhesives, it has a strong acid resistance and reduces the cost of the formulation. It also controls shrinkage, improves dimensional stability, changes viscosity, and colors the adhesive.
By providing a convoluted route, the inherent platy shape of kaolin clay gives good barrier characteristics in sealants. Calcined kaolin clays with low surface moisture content work well in moisture-sensitive sealant applications.
The refractory industry uses a variety of alumino-silicate clays, including kaolin. The alumina concentration of these clays ranges from about 20% to 45.9% for pure kaolin. It means, the higher the alumina concentration, the higher the refractory property of the material.
Heat-resistant materials used to line reactors, high-temperature furnaces, and refractories. The capacity of refractories to preserve their strength and form at high temperatures under mechanical stress and assault by a range of liquids, hot gases, and liquid or molten materials is their most significant property.
When it comes to cosmetics, kaolin is the gentlest type of clay. Compared to bentonite clay, kaolin clay does not dry up your skin and does not absorb moisture or the skin’s natural oil. You can readily tell the difference. The skin will not get red after a kaolin treatment. You may use a kaolin clay mask once a week to keep your skin from becoming too dry.
In its function, kaolin clay will absorb excess oil from your skin’s surface, allowing pores to remain clean. It simply reduces excess sebum production on the skin’s surface and does not affect its normal oil level.
The kaolin bricket machine is used to make briquettes from coal fines, charcoal powder, carbon black, gypsum powder, and other materials. This equipment is widely utilized in the coal and metallurgical industries.
Because of its energy-saving and environmental-friendly characteristics, the kaolin bricket machine is extensively utilized. Not to mention that it is simple to transport and emphasizes waste utilization for economic and environmental reasons.
5. China Porcelain and Tableware
Many people believe that the only application for kaolin is in the production of china. This is not the case, and its usage in the paper sector significantly outnumbers its other applications. Kaolin, on the other hand, remains an important component in china and other tableware. Its hue, gloss, and hardness make it perfect for such items.
Related: The History of Porcelain and the Use of Kaolin in Its Process
6. Paint and Coatings
While kaolin is not a perfect substitute for titanium dioxide, it is a good and cost-effective extender that aids in the reduction of production costs in a variety of architectural paints and coatings.
However, the advantages do not end there. Kaolin also improves opacity and tint strength, pigment suspension, sheen control, stain and scrub resistance, and holdout.
Related: All You Need to Know about Kaolin Clay as Paints & Coatings
Now that you know where the kaolin powder came from and the vast range of functionality it entails. You might want to start looking out paints, furniture, or China that has kaolinite in it for its excellent qualities.