Casting sand - what is best?

My Grandad and Father left me an old ranch with many old machines on it. In some of my other video's I have been documenting them and explaining there function during a walk-around.
The ranch also has a lot of old iron that needs to be scrapped or used in some fashion. There are some cool things I would like to build in my future, so looking into turning scrap iron into something more useable!
I am discovering, everything in the steel business is rather expensive! Especially, that can produce a large volume. After suffering through 2 years of drought, I believe it is time to look at something else!
Casting sand seems to be a major expense and draw-back to making a quantity of steel, so I have uploaded this video to get your response.
Of course, if you want to follow along you know what to do.