Different Types of Clay

kedi (63)in #steemstem • 9 years ago

Clays, which have been used since the beginning of civilization, is among the most important industrial raw materials today. People who see the hardening of some of the lands that are burning with fire have made various ceramic pots, bricks, and idols from these lands that named clay today. Under the influence of strong air currents, the clays formed by the erosion of the rocks are stored either in the place where they were formed or as wind and water and in other sands in large beds.

For ceramics, the clay exhibits a plastic feature that can be shaped when heated. It is a natural solid which hardens when it is dried or overheated. Chemical analyses have shown that the clay is aluminum silicate or magnesium silicate compounds with high water retention and ion exchange capacity. Depending on the chemical composition of the minerals and minerals, the natural clay color can be in various shades of white, gray, green, blue, pink and brown.

Clays are important raw materials that have entered into the life of human beings with fire.

Today, they have extensive use areas. If we think that many of the materials we need in our lives are ceramics, the fact that clay is the main material of this very wide range reveals the importance of this raw material to a certain extent. In addition to ceramics, clays, which are important raw materials for a wide variety of industrial fields, have attracted the attention of researchers in agriculture, geology and many other fields, and have been the subject of research by diverse disciplines from the past to the present. So, in this article, I would like to give brief information about what the clays are, what they are doing and their functions in the world.

Clays have very different characteristics. Clays with the same color, the same appearance, the same texture can have very different features. These different physical features acquired due to differences in chemical composition reveal their usability in various fields. Clays also give information about the physicochemical conditions of the environment in which they are secondary minerals. The abundance of these minerals, which are both industrial raw materials as well as being a guide in the interpretation of the environment, have increased their importance.

Clay is a soft, very fine grain material. The atoms in the clay material are either a cage or a chain array. The base material of the clay is aluminum silicate hydrate, which can also contain other elements such as Sodium (Na), Potassium (K), Calcium (Ca), Magnesium (Mg) and Iron (Fe). The results of the chemical analyses were combined with the X-ray diffraction studies initiated by L. Pauling in the 1930's, revealing that the clay minerals were composed of two different building blocks. At the center of the silicium, ion corners are tetrahedron like the first structure with oxygen ions. These uniform tetrahedron structures, whose chemical formulas can be written as SiO-44, are joined together by their oxygen bridges and hexagonal rings, resulting in a silica layer.

Fig-2-Smectite-structure-of-a-2-1-clay-mineral-showing-two-tetrahedral-sheets.png

The second structure, which has oxygen ions in the center of the aluminum ion corners, is in the form of an octahedron. The octahedron layer emerges when the uniform eight-faces, which can be written in the chemical formula AlO-66, combine with the oxygen bridges of the oxygen so that the faces of the regular eight faces remain on the same plane.

Types of Clay

Clays are found in various types according to their purity grades and physical conditions. These are,

Kaoline
Symmetrical
Plastic
Bentonite

The most important clay varieties like these and more are available. I will briefly mention these clay varieties according to their importance.

Clay Type	Features
Kaoline	It is the purest form of clay. The color is white, and after it has been heated, it will remain white again. The purity is 90% after cleaning with water.
Symmetrical	Contains some foreign materials especially lime and magnesium. It is used as a color or degreaser.
Plastic	It is usually called brick killer because it is a group of clay used in the production of bricks and pots. In this type of composition of the clays, iron oxide and lime are always present except silica and aluminum. The proportions of these components vary. (SiO₂ : % 57,64, Fe₂O₂ : % 3,5, Al₂O₂ : % 27.35 CaO₂ : % 7)
Bentonite	Montmorillonite type complex, aluminum, iron, and calcium, sometimes sodium silicate, has a swelling property by bringing a gel into the water and they are also used in many areas. When they are converted into sludge, they are found in colloidally dispersed silicates in bentonites which show plastic properties.