A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

H

Hammer and Tap       The process of drilling holes in hard rock by manually hitting and turning (rotating) a drill steel.

Haulage       The horizontal transport of ore, coal, supplies, and waste. The vertical transport of the same is called hoisting.

Haulageway       Any underground entry or passageway that is designed for transport of mined material, personnel, or equipment, usually by the installation of track or belt conveyor.

Head section       A term used in both belt and chain conveyor work to designate that portion of the conveyor used for discharging material.

Headframe       The structure surmounting the shaft which supports the hoist rope pulley, and often the hoist itself.

Heading       A vein above a drift. An interior level or airway driven in a mine. In longwall workings, a narrow passage driven upward from a gangway in starting a working in order to give a loose end.

Heaving       Applied to the rising of the bottom after removal of the coal; a sharp rise in the floor is called a "hogsback".

Hedging       Taking a buy or sell position in a futures market opposite to a position held in the cash market to minimize the risk of financial loss from an adverse price change.

Highwall       The unexcavated face of exposed overburden and coal in a surface mine or in a face or bank on the uphill side of a contour mine excavation.

Highwall miner       A highwall mining system consists of a remotely controlled continuous miner which extracts coal and conveys it via augers, belt or chain conveyors to the outside. The cut is typically a rectangular, horizontal cut from a highwall bench, reaching depths of several hundred feet or deeper.

Hogsback       A sharp rise in the floor of a seam.

Hoist       A drum on which hoisting rope is wound in the engine house, as the cage or skip is raised in the hoisting shaft.

Hoisting       The vertical transport coal or material.

Horizon       In geology, any given definite position or interval in the stratigraphic column or the scheme of stratigraphic classification; generally used in a relative sense.

Horseback       A mass of material with a slippery surface in the roof; shaped like a horse's back.

Hydraulic       Of or pertaining to fluids in motion. Hydraulic cement has a composition which permits it to set quickly under water. Hydraulic jacks lift through the force transmitted to the movable part of the jack by a liquid. Hydraulic control refers to the mechanical control of various parts of machines, such as coal cutters, loaders, etc., through the operation or action of hydraulic cylinders.

Hydrocarbon       A family of chemical compounds containing carbon and hydrogen atoms in various combinations, found especially in fossil fuels.