The furnace inner lining, that consists of materials such as sand, silicon-containing rocks, or bricks with silica, which provide acid reaction at operating temperatures.
(1) A substance added into a solution to change its properties or control the process. Examples: acid baths moisturizers; anti-pitting additives in metals; inhibitors. (2) Any material added to molten metal in a bath or ladle enabling a specific composition of an alloy.