This category covers establishments primarily engaged in the pipeline transportation of commodities, except crude petroleum, refined products of petroleum, and natural gas. Establishments primarily engaged in the pipeline transportation of refined petroleum are classified in SIC 4613: Crude Petroleum Pipelines, and those engaged in natural gas transmission are classified in SIC 4922: Natural Gas Transmission and Distribution. Most notably, the industry includes coal slurry pipeline operations and metal ore concentrates.
All Other Pipeline Transportation
More than a dozen firms operate about 60 establishments primarily engaged in the operation of pipelines for the transportation of coal slurry, metal ore slurry, and phosphate slurry. This industry's employment comprises only a scant percent of the total employment for the broader pipeline industry, which mainly operates petroleum and natural gas pipelines. Most of the U.S. pipelines operated by this industry transport coal suspended in water (crushed and mashed coal mixed with water creates slurry). Slurry systems are a competitive method in cost for transporting coal. The expense associated with building roads and railroads to the mouth of mines can be prohibitive, and the slurry alternative requires a smaller capital investment. As such, the Black Mesa Company began operating a coal slurry line in 1970 that transported coal 273 miles from a mine in northeast Arizona to a power plant in Laughlin, Nevada. This became the prototype for most slurry pipelines, and by the late 1990s pipelines stretched as long as 1,500 miles.
Coal slurry technology involves transporting pulverized coal suspended in water and pumped through pipelines. From the mine, the coal is crushed, formed into slurry, suspended in water, and pumped through the pipe to the power plant. At the end of its journey, the slurry enters storage tanks, where various processes remove the water. The final result is coal that can be used for burning.
Modern slurry systems were initially developed after World War II; although coal is the most common commodity transported via slurry, other concentrates—iron-ore concentrate, copper ore, phosphate-rock concentrate, limestone, and the mineral gilsonite—are transported as well. The South American Alumbrera pipeline, completed in early 1998, is the world's longest copper ore concentrate slurry pipeline, traversing 312...