Rust problem on Acrylic Yarn

[Paulaque]

I bought a bunch of yarn on a yard sale site on FB, my husband fell in love with one of the skeins, it is a brown/tan/white varigated yarn, and asked me to make him a muffler out of it, I am halfway through the project when I notice the yarn is very rough, then I get to a white section, and I see rust. Completely mystified me. I unwound the skein and there is very little left of an old crochet needle in the skein. I do not want to give up on this piece of knitting, so does anyone know a way to get rust out of this yarn. The rust is occuring about once a yard or so, so there will be quite a few stains on it when I finish, and it does not blend in, it looks horrid.