Bone ash

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Bone ash is a white, powdery substance primarily composed of calcium phosphate derived from the calcination of bones. It is used in various industrial applications, including the production of bone china, fertilizers, and as a source of phosphorus in the manufacture of phosphoric acid.

Production

Bone ash is produced by heating bones to high temperatures in the absence of air, a process known as calcination. This process removes organic materials and leaves behind the inorganic mineral components, primarily calcium phosphate (Ca₃(PO₄)₂). The bones are typically heated to temperatures between 800°C and 1000°C.

Composition

The primary component of bone ash is calcium phosphate, which constitutes about 80% of its composition. Other components include calcium carbonate and small amounts of magnesium phosphate and calcium fluoride. The exact composition can vary depending on the type of bones used and the conditions of the calcination process.

Uses

Bone China

Bone ash is a key ingredient in the production of bone china, a type of porcelain known for its high levels of whiteness and translucency. The bone ash is mixed with kaolin and feldspar to create a paste that is then shaped and fired at high temperatures.

Fertilizers

Bone ash is used as a source of phosphorus in the production of fertilizers. Phosphorus is an essential nutrient for plant growth, and bone ash provides a slow-release form of this nutrient.

Phosphoric Acid Production

Bone ash is also used in the manufacture of phosphoric acid, which is a key ingredient in many industrial and food products. The calcium phosphate in bone ash reacts with sulfuric acid to produce phosphoric acid and calcium sulfate.

Historical Context

Historically, bone ash has been used since ancient times for various purposes, including as a fertilizer and in the production of ceramics. Its use in bone china dates back to the late 18th century in England, where it was first developed by Josiah Spode.

See Also

• Calcium phosphate
• Bone china
• Phosphoric acid
• Fertilizer
• Calcination