Tmoose,
Coal dust is only a problem in and immediately adjacent to coal handling facilities and equipment. The "everywhere" dust that your are probably addressing is flyash. Coal dust is a BIG issue because of the risk of fire, but flyash is inert and only a big nuisance.
Coal dust control ALWAYS gets really serious attention, and everything involving coal handling must be and is treated with every possible concern for fire and dust "explosion" hazards. Coal from different sources can have widely differing dusting characteristics and differing requirements for proper, safe handling. This, along with differing firing characteristics, is why plants do not change coal sources without very careful evaluation and preparation.
You can safely presume that no coal fired power plant will allow any non-safety-compliant equipment anywhere near coal dust areas. Everyone in a coal fired plant gets paranoid about coal dust safety issues. Since you are apparently not familiar with this aspect of coal fired plant life, I very much doubt that your equipment has been going into coal handling areas.
I agree with rmw that TEFC motors are generally a good first choice, but there are very good reasons to use other types as well. TEFC motors tend to run slightly higher internal temperatures, and many places in power plants have very high ambient temperatures where open drip-proof motors can work well at much lower cost. Most old power plants (roughly first half of 20th century) used open motors with very good results despite abundant flyash. Where necessary "custom" sheet metal guards or shields were installed to protect the open motors rather than using open drip-proof motor construction. Those old motors were VERY rugged and VERY conservatively rated. I've seen some of those old beasts carry nearly double their rated load without overheating.
