A process using a fixed quantity of material that is placed within the process equipment and the operation carried out to completion. Described as a closed system, no material is transferred to or from the system during the time of interest, and can be described using differential material and energy balances. The process may involve several sequential steps but in each the material is kept and processed together. Commonly used for speciality chemicals, pharmaceuticals, and food processing, batch processes include mixing, reaction, and separation. Reactor volumes are generally correspondingly larger than those of continuous processes. The operating costs, including labour costs, are also higher due to materials handling and greater charging and down-times costs. Scotch whisky production is an example of a batch process in which malted barley grain is batch fermented and batch distilled.