Written by Merle Travis and a big hit for him, various lines were said to have come from members of his family: "You load sixteen tons and what do you get? Another day older and deeper in debt," came from a letter written by Travis' brother John, while his father was fond of claiming that "I can't afford to die. I owe my soul to the company store."
The company store was a way of mine owners (and owners of other industries) keeping the money which they paid to their employees: Workers were paid in credit redeemable at a shop owned by their employers and, given that they were a captive market, often ripped off.
George Davis, a folk singer claimed that, in fact he had written the song (called Nine to Ten Tons) in the 1930s, but never recorded it (he finally recorded a version of his song in 1966); it's amazingly similar lyrically, but may, of course, have evolved to become more like the Merle Travis version in the time between writing and recording.
As for versions:
80s lefty skinheads The Redskins did a version, which is well worth seeking out, but it's not on YouTube.