First interview was a phone interview to just cover basic questions. I think this is more so to make sure you are normal and can hold a conversation well (since you will spend much of your time on the phone). This phone call will most likely be with an HR Representative.
If you pass this process, they bring you in to their headquarters where you will be interviewed by a variety of managers and grain merchandisers. This is pretty much the extent of it, nothing too extravagant or outside of the norm, which is a good thing.
The people doing the interviewing are just normal guys/girls, but it may seem a little intimidating to some people just by virtue of how intense looking the trade floor is.