Ralph,
Yes, I did scratch build the conveyor system. The conveyor belts were made from cutting wooden strips on my table saw and simply painting them gray. I will probably add some painted detail later, but for now they are plain gray in color. The conveyor supports were leftover sprues from the Bachman Car Shop kit that I kept in the hope of finding a use for them. They were already gray, so the color was right. On the top of each support tower, I made a little structure (also made from leftover Car Shop parts--doors and windows, I think) to conceal the ends of the overlapping belts.
The end of the converyor system and the main building of the cement plant was a Walther's New River Mining stucture that I cut in half and placed in an "L" in order to get the structure going the right way over the tracks. Into one side of the mine structure I ran a PVC pipe (kiln) that has plastic centers from cash register paper glued together and encircling the kiln. Most of the cement silos are made from PVC pipe pieces that were given to me by a local plumber (they were too short to be of much use to him). I glued some styrene to the top and bottom, painted the whole thing gray and added a few other bottles and PVC pipes to make the structure more convincing. The car loading tower is from the Walther's coal loading kit with a scratch built plastic pipe connecting it to the main silos.
The cement plant office bulding was built from two different Pikestuff kits (I don't recall the names at this time). The sacked cement warehouse is a red structure from a Wathers sawmill kit or lumber wholesaler. I'm still looking for something else for this part of the plant, but it will do for now. If I decide to keep it where it is, it will be repainted something other than the red that it is now.