There is really no way to build a coal fire without smoke. Coal is made up of compounds that kindle and ignite at different temperatures. Unless the fire is burning at very high temperatures, some of these compounds simply turn to gas and go up the stack as smoke. When building a fire from scratch, significant smoke is created until the fire is burning hot enough to allow all the compounds to to burn cleanly. Adding more air to the fire will not clear the smoke, only a hotter fire will do that.
Once the auxiliary heating source - be it a gas burner, electic heater, aux boiler, etc. is removed, it will be difficult to start a new coal fire without lots of smoke and anytime to put out one heatv source and start a new one you run the risk of shocking the boiler by introducing cold air into the firebox until the new fire is hot enough to produce steam.
All of this does not address the little kid's comment in the paper. She saw a moving train making smoke. Not one sitting in the house. The problem in Dueango is a nasty one - few people are left there who understand what drives the local economy. They do not understand - or want to understand that coal smoke is heavy particulate matter that settles to the ground and makes the grass and wildflowers grow. These folks do much more damage to the environment driving thier Tahoe's to work every day.