Some follow-up on my paddle wheel muller. I've put about 1000 pounds of sand through it now. I really really like the way it performs. I definitely see both improvement in speed of mulling and reduction of lumps of previously-used green sand. It takes about 1/2 the time of the prior setup and sand lumpiness is significantly better. How that would generalize to other users and their mullers is a good question. I'll grant that it is a design design that may seem a bit counterintuitive, but it works well. Why do I think it works well? I think that the paddles do crush lumps both as the end of the paddle rotates near the floor of the muller and I also think sand "trapped" between the adjoining paddles is compressed some and that likely collapses lumps. It also mixes the sand rapidly and does not plow at all. FWIW, Denis