Arnold O. Tanner, a mineral commodity expert at the US Geological Survey, compiled the following information about iron oxide pigments.
Before the royal wedding in 2011, the roads and sidewalks around Buckingham Palace in London were repaved with stone mastic asphalt dyed red with synthetic iron oxide pigments. Image source: ©Misterweiss.
Iron oxide pigments, natural or synthetic, are inorganic materials commonly used as colorants. They are valued for their resistance to discoloration (especially exposure to sunlight), chemical resistance, stability under ambient conditions, non-toxicity and relatively low cost.
The main mineral that constitutes natural iron oxide pigments is hematite used for red pigments; goethite and limonite (hydrous iron oxide) are used for yellow and brown pigments, commonly found in iron oxide-rich ocher, ocher and brown Brown; and magnetite is used in black pigments. Natural iron oxide pigments were used as colorants for human body decoration and paintings on cave walls in early civilizations, revealing details of prehistoric culture.
Synthetic iron oxide pigments were originally developed by the chemical industry in the early 20th century and surpassed pigments produced from natural iron oxide minerals in terms of uniformity, color quality and diversity, and chemical purity. They are manufactured under controlled conditions to accurately replicate particle size, distribution and shape.
Today, the main use of natural and synthetic iron oxide pigments is to provide color for building materials, paints and coatings. Construction applications include bricks; concrete products, such as paving stones, roof tiles, and other prefabricated products of various sizes or sizes; mortar; and ready-mixed concrete. Other end uses include colorants for ceramics, glass, paper, plastic, rubber, and textiles; foundry sand and industrial chemicals; and animal feed, cosmetics, fertilizers, magnetic inks and toners.
Natural pigments are generally used in applications that require less color consistency, such as primers and primers, but synthetic pigments occupy a larger market share in most applications. In paints and coatings, the overlapping arrangement of mica iron oxide flake particles greatly improves the material’s resistance to moisture and gas penetration-preventing metal corrosion and rusting-as well as blistering, cracking and peeling.
Iron oxide pigments are produced from natural deposits in many countries, including Austria, Cyprus, Germany, India, Pakistan, Spain, Turkey and the United States. Many countries produce synthetic iron oxide pigments.
For more information about iron oxide pigments and other mineral resources, please visit: minerals.usgs.gov/minerals.
In 2014, the United States produced approximately 50,000 tons of finished natural and synthetic iron oxide pigments.
In 2014, the United States exported approximately 60,000 metric tons of various grades of iron oxide and hydroxide, mainly to China, Spain, Canada, and Mexico.
In 2014, India was the world’s leading producer of natural (ochre) iron oxide pigments, with an output of approximately 1.4 million tons.
In the mid-1990s, paint and paint grinding equipment estimated to be 350,000 to 400,000 years old were discovered in a cave near Lusaka, Zambia.
A group of researchers in Spain and Finland demonstrated in 2011 that atmospheric sulfur dioxide may have caused the red iron oxide pigment in the paintings of the ruins of Pompeii, Italy to turn into black spots (by reducing hematite to magnetite).
In recent years, the remediation of soil and water contaminated in acid coal mine drainage has increasingly become a “green” source of iron oxide pigments, some of which are used to produce artist oils and acrylic paints.
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Post time: Oct-31-2021