What is Mineral Fiber?
Mineral fiber is a generic term for all non-metallic inorganic fibers. Mineral fibers are derived from inorganic natural sources. Mineral fibers are of less importance in the textile trade. Glass and asbestos are the most commonly used mineral natural fibers. But the most important and useful fiber material among the mineral fibers is asbestos (AS). Asbestos occurs naturally as fiber. A synthetic mineral fiber known as rock wool or slag wool is produced by blowing air or steam through molten rock or slag. It is soft and flexible and good insulator of electricity, heat, and corrosion. Mineral fibers are used as fillers in fireproofing and thermal insulation materials.
Properties of Mineral Fibers:
Mineral fibers generally have a high thermal performance, are combustible and are relatively impermeable. The primary useful physical properties of mineral fibers are its outstanding thermal stability and very high tensile strength. It can melt, but only at 1450°-1500°C (2580°-2670°F), the temperature of lava in a volcano. Its tensile strength surpasses that of steel. Properties / Characteristics of mineral fibers are point out below.
- Mineral fiber has good insulations properties
- It has good fireproofing properties used in clothing, conveyor belts.
- It has good soundproofing properties.
- It is also acid-proof, and rust-proof.
- It has low electrical and thermal conductivity.
- It does not deteriorate in normal usage,
- It is not attacked by insects or microorganisms,
- It is used in brake linings, gaskets, industrial packing, electrical windings,
- It is a fibrous form of silicate of magnesium and calcium-containing iron and aluminum and other minerals
- It has been a serious health hazard and removed from the textiles market.
Types / Classification of Mineral Fiber:
Natural fibers are mainly classified as vegetable fibers, animal fibers, and mineral fibers depending on the origin. According to the International Mineralogical Association and the French Agency for Environmental and Occupational Health Safety (AFSSET), mineral fiber is obtained by melting and then fibrating various minerals. There are two types of mineral fiber:
The ones that come directly from rocks in the form of fiber. Asbestos is the only mineral fiber that is natural. Asbestos, wollastonite, and sepiolite are natural mineral fibers.
Other ones are artificially produced from minerals. These fibers are classified into three categories: vitreous fibers (glass fiber, glass wool, rock and basalt fiber, slag wool, refractory ceramic fibers), crystalline fibers (alumina fiber, potassium titanate fiber, and carbon fiber), and metallic fibers (steel wool, stainless wool, copper wool).
In this article I will discuss important types of mineral fibers.
Asbestos fiber is the only naturally occurring mineral fiber-like serpentine, amphiboles, and anthophyllite. Asbestos is recovered from the rocks which have crystallized in the fibrous form. Asbestos fiber had been used as early as 2500 years ago. Asbestos was renowned for its resistance to fire and used in buildings for fire protection. It also limits electrical and chemical damage.
Traditionally, the hard mats on ironing boards were made from asbestos, but today, they are made from a man-made material. The largest mining areas can be found in Russia (46% market share), China and Kazakhstan (16% each), Brazil (10%), and Canada (8%). The fibers are extracted from rocks and can be spun into yarns. The yarns can then be processed into wovens, knits, and other textile fabrics. The fibers can also be added to other materials such as concrete and are very suitable for insulation. The outstanding property of asbestos fiber is its resistance to heat and burning. They are also highly resistant to acids, alkalis, and other chemicals. These fibers are used to make special fire-proof and industrial fabrics.
Compared to natural and chemical fibers, asbestos fibres are extremely fine. The diameter of the elementary fibers varies between 0.02 and 0.2 μm. Further advantages of asbestos are its high-temperature stability and low cost. For these reasons, large amounts of asbestos have been mined and processed worldwide. In 1987, the world production was approximately 4 million tons, but this amount has declined in recent years.
The use of asbestos has been known since ancient times when it was used as wicks in lamps. There has been extensive research to replace asbestos with other natural and chemical fibers in various fields of application, such as work and fire protection, with heat and electrical insulation, as seals, in filtration, in friction linings, and technical products for construction (asbestos concrete) as well as with chemical products.
Asbestos is used in all types of protective equipment for fire fighting, fire screens, insulation for steam and hot pipes, brake lining insulative building materials, tapes and braids for electrical uses and items wherein non-combustibility is essential. Many times asbestos fiber is used with glass in making decorative fabric for curtains and draperies and for heat insulation.
Fine asbestos dust and fine dust containing asbestos are considered to be carcinogenic. In this case, the size of the dust corns and the fibers and not the asbestos material itself poses the problem. For this reason, the use of asbestos in Germany has been reduced significantly. However, health concerns have diminished their use, especially asbestos, which is banned in many countries.
Ceramic fibers are inorganic materials that include glass, silicon carbide, boron carbide and aluminium oxide. Generally ceramic fibers are differentiated from glass. In ceramics, the structure of the main constituent, namely silicon dioxide tetrahedra, is crystalline or partly crystalline and opaque. In glass, the tetrahedra (SiO4) arrangement is random and amorphous. Glass is a transparent amorphous solid. Glass as an inorganic substance in a condition that is continuous with and analogous to the liquid state of that substance, but which, due to changes in viscosity during cooling, has attained a high degree of viscosity rendering it rigid. Glass is typically 50% silica and consists of boron oxide, aluminium and several other minerals.
Examples from the ceramic fiber are glass fibers, aluminum oxide, silicon carbide, and boron carbide. Glass wood and quartz can be categorized into the glass fiber group.
Basalt is naturally available worldwide. It is eco-friendly in nature; its fibers are produced by the process of drawing and winding fibers from the melt. It has good fire resistance, is chemically inert and can tolerate impact load.
Basalt is a natural mineral from the rock lava and can be used to produce high temperature-resistant and chemically inactive products. When extracted from volcanic rocks, basalt fibers are practically amorphous, and at high temperatures, the fiber crystallizes partially depending on the quenching temperature. Basalt largely consists of plagiocene and pyroxene, which are SiO2 and Al2O3 compounds, respectively, and is chemically highly stable in strong alkalis. In strong acids, basalt has a relatively low stability. Basalt is a non-polymeric fiber; hence, it has a low elongation to fracture property of 3.15%. Other properties include a tensile strength of 2.8 GPa and a density of 2.8 g/cm3.
Brucite is the mineral form of magnesium hydroxide; it has good anti alkaline properties. It is more stable in an alkaline medium than glass fiber. The moderate strength of this fiber can reach up to 900 MPa.
- Textile Technology: An Introduction, Second Edition by Thomas Gries, Dieter Veit, and Burkhard Wulfhorst
- Handbook of Textile Fibres: Natural Fibres by J. Gordon Cook
- Bombac, D.; Lamut, M.; Mrvar, P.; Širok, B.; Bizjan, B. Physical Properties of Mineral Fibers Depending on the Mineralogical Composition. Materials 2021, 14, 6108. https://doi.org/10.3390/ma14206108
- Natural Fibre Composites: Manufacturing, Characterization, and Testing By Mohamed Zakriya G. and Ramakrishnan G.
- Introduction to Textile Fibres by V. Sreenivasa Murthy
- Forensic Examination of Fibres, Third Edition Edited by James Robertson, Claude Roux and Kenneth G Wiggins
- Lopamudra Nayak “The Mineral Fibre: Asbestos – Its Manufacture, Properties, Toxic Effects and Substitutes” www.neptjournal.com
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- Asbestos Fiber: History, Manufacturing Process and Uses
- Types, Properties, Production and Application of Ceramic Fiber
- Types, Properties and Application of Vegetable Fibers
- Textile Fibers and Their Classification
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.