Exploring Diatomaceous Earth: A Stone Industry Staple with Surprising Uses

Frederick M Hueston  StoneForensics.com

Many of us in the stone industry are familiar with using diatomaceous earth in poultices for effective stain removal, but have you ever wondered what diatomaceous earth actually is and where it comes from? This naturally occurring, powdery substance is not just a secret weapon for tackling tough stains on stone surfaces; it has a fascinating origin and a wide array of uses that extend far beyond our industry. Let’s delve into the world of diatomaceous earth to uncover its composition, properties, mining locations, manufacturing processes, and the diverse applications it holds in various fields.

Composition and Properties:

Diatomaceous earth is primarily composed of silica (silicon dioxide), constituting about 80-90% of its makeup. This silica comes from the fossilized remains of diatoms, a type of microscopic algae with a hard-shelled body. These unique properties give diatomaceous earth its high porosity and abrasive nature.

Other Minerals: Along with silica, diatomaceous earth contains small quantities of other minerals like alumina, iron oxide, and traces of calcium and magnesium. These contribute to its varied uses and effectiveness in different applications.

Uses of Diatomaceous Earth:

Pest Control: The abrasive quality of diatomaceous earth makes it a potent natural pesticide. It works by absorbing the lipids from the exoskeletons of insects, leading to dehydration and death.

Filtration: Its fine particulate size and porosity make it ideal for filtration purposes, including water treatment, pool filtration, and in the production of beer and wine.

Agricultural Applications: In agriculture, diatomaceous earth is used as a natural pesticide, soil amendment, and as an additive in animal feed.

Industrial Uses: It’s incorporated into various industrial products such as paints, plastics, and rubber, serving as an anti-caking agent and stabilizer.

Health and Beauty: Diatomaceous earth finds its way into toothpaste and skincare products, and is sometimes consumed as a dietary supplement, though its health benefits in this context are subject to debate.

Mining and Manufacturing:

Diatomaceous earth is mined from the sediment of dried lakes, rivers, and ocean beds, primarily in regions such as the United States, China, Denmark, and Mexico. The extraction process involves quarrying the earth, followed by a series of processing steps including crushing, drying, and milling.

Calcination: Some diatomaceous earth undergoes a calcination process, involving high heat treatment to enhance its strength and chemical stability. This changes its color and properties, making it more suitable for certain applications like pool filtration.

Types of Diatomaceous Earth:

Food Grade: This form is not calcined and has a lower silica content. It’s safe for agricultural use and as a dietary supplement.

Filter Grade or Pool Grade: A calcined form with higher silica content, used primarily for filtration due to its increased crystalline structure.

Safety Considerations:

While food-grade diatomaceous earth is generally safe, inhaling the dust, particularly of non-food grade varieties, can be harmful to the respiratory system. Therefore, precautions should be taken during handling, especially in industrial or agricultural settings.

In the stone industry, diatomaceous earth is a valued tool for removing stains, but its utility extends far beyond this. From pest control to filtration, and even in health and beauty products, this versatile material plays a crucial role in numerous sectors. Understanding its origins, composition, and the processes involved in its production not only highlights its importance but also informs safer and more effective usage in various applications.