Wind Gypsy,
IDK how it compares to the paper mill 'byproduct' your neighbor is having spread, but several years back, I saw a presentation by Dr. Bob van Saun (PennSt.U veterinarian) on a farm that had uses an 'alkalinizing' product which was a waste/byproduct of some automobile parts polishing process... much cheaper than lime, and did, indeed, alter pH. But... the fairly immediate, and long-term effects on health and reproduction of the livestock on that farm was devastating. At this point, I don't remember what else was in that product (cadmium, molybdenum, etc.), but sometimes a 'cheap fix' is way more costly in the long run.
With all the stuff now coming forward about 'forever chemicals' (PFAS, etc.), I'm pretty sure I don't want anyone spreading industrial waste on my property.