mold

If your talking about the soil having some cottony mold over just the top layer. I've had that happen before, The mold survives on dark and moist conditions(I'm pretty sure), I took that batch of soil, opened it up real wide to expose as much as possible, and left it in front of the window in another room. After about 3 days(and a few mixings), the soil was completely dried out and apparently mold free. I then used that soil(promix BX(no nute value)) without issue.
I am not telling you that this is ok. I took the risk knowing that it may cost me a crop. It didn't cost me my crop that time, But thats no guarantee. I've since started being more careful about soil storage. In fact, my stored soil gets a controlled environment now just like my girls. Low on humidity, heat and a random light on/off timer.