What is "roasting"

Roast \Roast\, v. t. [imp. & p. p. Roasted; p. pr. & vb. n. Roasting.] [OE. rosten, OF. rostir, F. r[^o]tir; of German origin; cf. OHG. r[=o]sten, G. r["o]sten, fr. OHG. r[=o]st, r[=o]sta, gridiron, G. rost; cf. AS. hyrstan to roast.]

1. To cook by exposure to radiant heat before a fire; as, to roast meat on a spit, or in an oven open toward the fire and having reflecting surfaces within; also, to cook in a close oven.

2. To cook by surrounding with hot embers, ashes, sand, etc.; as, to roast a potato in ashes.

   In eggs boiled and roasted there is scarce difference to be discerned.
   --BAcon.

3. To dry and parch by exposure to heat; as, to roast coffee; to roast chestnuts, or peanuts.

4. Hence, to heat to excess; to heat violently; to burn. ``Roasted in wrath and fire.''
   --Shak.

5. (Metal.) To dissipate by heat the volatile parts of, as ores.

6. To banter severely. [Colloq.]
   --Atterbury.

Roasting \Roast"ing\, a. & n., from Roast, v.

Roasting ear, an ear of Indian corn at that stage of development when it is fit to be eaten roasted.

Roasting jack, a machine for turning a spit on which meat is roasted.

1. Very hot n. The act by which something is roasted. v

2. (present participle of roast English)

n. cooking (meat) by dry heat in an oven (usually with fat added); "the slow roasting took several hours"

Roasting is a cooking method that uses dry heat where hot air envelops the food, cooking it evenly on all sides with temperatures of at least 150 °C (~300 °F) from an open flame, oven, or other heat source. Roasting can enhance flavor through caramelization and Maillard browning on the surface of the food. Roasting uses indirect, diffused heat (as in an oven), and is suitable for slower cooking of meat in a larger, whole piece. Meats and most root and bulb vegetables can be roasted. Any piece of meat, especially red meat, that has been cooked in this fashion is called a roast. A roast joint of meat can take one, two, even three hours to cook—the resulting meat is tender. Also, meats and vegetables prepared in this way are described as "roasted", e.g., roasted chicken or roasted squash.

Roasting is a step of the processing of certain ores. More specifically, roasting is a metallurgical process involving gas–solid reactions at elevated temperatures with the goal of purifying the metal component(s). Often before roasting, the ore has already been partially purified, e.g. by froth floatation. The concentrate is mixed with other materials to facilitate the process. The technology is useful but is also a serious source of air pollution.

Roasting consists of thermal gas–solid reactions, which can include oxidation, reduction, chlorination, sulfation, and pyrohydrolysis. In roasting, the ore or ore concentrate is treated with very hot air. This process is generally applied to sulfide minerals. During roasting, the sulfide is converted to an oxide, and sulfur is released as sulfur dioxide, a gas. For the ores CuS ( chalcocite) and ZnS ( sphalerite), balanced equations for the roasting are:

The gaseous product of sulfide roasting, sulfur dioxide (SO) is often used to produce sulfuric acid. Many sulfide minerals contain other components such as arsenic that are released into the environment.

Up until the early 20th century, roasting was started by burning wood on top of ore. This would raise the temperature of the ore to the point where its sulfur content would become its source of fuel, and the roasting process could continue without external fuel sources. Early sulfide roasting was practiced in this manner in "open hearth" roasters, which were manually stirred (a practice referred to as "rabbling") using rake-like tools to expose unroasted ore to oxygen as the reaction proceeded.

This process would release large amounts of acidic, metallic, and other toxic compounds. Results of this include areas that even after 60-80 years are still largely lifeless, often exactly corresponding to the area of the roast bed, some of which are hundreds of metres wide by kilometres long.