Process for the Manufacturing of Goethite Pigments

Simple SummaryContent extracted from patent full text and abstract with AI.

This patent describes a new process for producing goethite (α-FeOOH) yellow iron oxide pigments. The method involves dissolving highly pure ferric nitrate in water, heating the solution, isolating the precipitated goethite, resuspending it, and subjecting it to hydrothermal treatment at high temperatures and autogenous pressure. This process yields spheroidal (round, not needle-like) goethite particles with improved color characteristics and high resistance to color change during milling.

Use CasesContent extracted from patent full text and abstract with AI.

• Coloring inks, paints, and coatings, especially in applications requiring consistent yellow hues.
• Pigmentation of building materials such as concrete, bricks, and tiles for decorative or functional coloring.
• Coloring plastics and paper products for packaging, consumer goods, and industrial uses.
• Use in foods, baking varnishes, or coil coatings where color consistency and purity are critical.
• Inclusion in pharmaceutical products, for example in tablet coatings, to provide color without instability during processing.
• Pigmentation of ceramics, enamels, and glazes with stable and vivid yellow tones.

BenefitsContent extracted from patent full text and abstract with AI.

• Produces highly pure, spheroidal goethite pigments with fine-tuned, vivid yellow color properties (high b* and L* values).
• Reduces or eliminates the silking effect (uneven color appearance due to pigment alignment), common with needle-shaped pigments.
• Pigments are highly resistant to color changes during milling and processing, ensuring consistent appearance in end products.
• Process is scalable and less sensitive to impurities than previous methods for spherical goethite, promoting industrial applicability.
• Enables use in a variety of applications, including demanding sectors like food and pharmaceuticals, due to purity and stability.
• Allows for efficient control over particle size, shape, and optical properties, resulting in better product performance.

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Patent Abstract

A process for manufacturing goethite containing the steps:a) Dissolution of ferric (III) nitrate in waterb) Treatment of the solution obtained according to step a) at a temperature in the range of 55° to 65° C,c) Isolating the goethite from the suspension obtained according to step b)d) Suspending the isolated goethite of step c) in watere) Treating the suspension of step d) hydrothermally at a temperature of 120 to 220 °C, preferably of 150 to 200 °C under autogenous pressure.