Briquette

A briquette (French: [bʁikɛt]; in English also spelled briquet) is a compressed block of coal dust or other combustible biomass material (e.g. charcoal, sawdust, wood chips, peat, or paper) used for fuel and kindling to start a fire. The term is a diminutive derived from the French word brique, meaning brick.

Coal briquettes have long been produced as a means of using up 'small coal', the finely broken coal inevitably produced during the mining process. Otherwise this is difficult to burn as it is hard to arrange adequate airflow through a fire of these small pieces; also such fuel tends to be drawn up and out of the chimney by the draught, giving visible black smoke.

The first briquettes were known as culm bombs and were hand-moulded with a little wet clay as a binder. These could be difficult to burn efficiently, as the unburned clay produced a large ash content, blocking airflow through a grate.

With Victorian developments in engineering, particularly the hydraulic press, it became possible to produce machine-made briquettes with minimal binder content. A tar or pitch binder was used, obtained first from gas making and later from petrochemical sources. These binders burned away completely, making it a low-ash fuel. A proprietary brand of briquettes from the South Wales coalfield was Phurnacite, developed by Idris Jones for Powell Duffryn. These were intended to emulate a high-quality anthracite coal, such as that from the Cynheidre measures. This involved blending a mixture of coals from different grades and colliery sources. Phurnacite used the following mix:

Early briquettes were large and brick-shaped. Phurnacite briquettes later adopted a squared oval shape. This regular shape packed well as a good firebed, with plentiful airflow. They are also easy to mechanically feed, allowing the development of automatically controlled heating boilers that could run for days without human intervention.

Charcoal briquettes sold for cooking food can include:

As a rule of thumb, a charcoal briquette will heat a camping Dutch oven by approximately 25 °F (14 °C), so 20 charcoal briquettes will heat it by 500 °F (280 °C).

Home made charcoal briquettes (called tadon [ja]) were found after charcoal production in Japanese history. In the Edo period, polysaccharide extracted from red algae was widely used as a binder. After the imports of steam engines in the Meiji period, coal and clay became major ingredients of Japanese briquettes. These briquettes, rentan [ja] and mametan [ja], were exported to China and Korea. Today, coal briquettes are avoided for their sulfur oxide emission. Charcoal briquettes are still used for traditional or outdoor cooking. Woody flakes such as sawdust or coffee dust are major ingredients of modern mass-consumed briquettes (e.g., Ogatan [ja]).