kieselguhr
/'ki:zəlguə/
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Definition
Noun: A soft, porous, and lightweight sedimentary rock composed primarily of the fossilized silica shells (frustules) of diatoms, a type of microscopic algae. It is also known as diatomaceous earth. Its key properties include high absorbency, low density, and abrasiveness, leading to its primary use as a filtering agent, absorbent, mild abrasive, and thermal insulator.
Usage and Examples
As a filtering material:
- The brewery uses kieselguhr to filter impurities from the beer, ensuring clarity.
- Kieselguhr is a common filter aid in the production of wine and syrups.
As an absorbent:
- Spilled liquid can be safely contained by covering it with kieselguhr.
- It is used in absorbent materials for cleaning up hazardous spills.
As a mild abrasive:
- Some toothpaste and metal polishes contain fine kieselguhr for its polishing effect.
In other applications:
- Due to its insulating properties, kieselguhr is used in some types of fireproof safes.
- Gardeners sometimes mix kieselguhr into soil to improve drainage and aeration.
Advanced Usage and Technical Context
- In scientific and industrial contexts, "kieselguhr" is the technical term, while "diatomaceous earth" (or "DE") is more common in general and commercial use. The term specifies the natural, uncalcined form.
- "Filter cake": In industrial processes, the spent kieselguhr that accumulates on a filter after use is often referred to as a filter cake.
- "Calcined kieselguhr": This refers to kieselguhr that has been heat-treated, which alters its properties for specific applications, such as creating a more stable filter aid.
Variants and Related Words
- Diatomaceous earth (n): The most common synonym for kieselguhr.
- Diatomite (n): Another technical synonym, often used interchangeably with kieselguhr, particularly for the processed mineral.
- Tripolite (n): A historical or regional name for a form of diatomaceous earth.
Synonyms
- Diatomaceous earth
- Diatomite
- Infusorial earth (an older term)
Notes on Different Meanings
The word "kieselguhr" has a single, specific technical meaning related to geology and industrial materials. It does not have common idiomatic or phrasal verb uses. Its usage is almost entirely confined to scientific, industrial, agricultural, and specialized commercial contexts.
Noun
- a light soil consisting of siliceous diatom remains and often used as a filtering material