I am not sure where this train of thought is coming from. First talking about the crucible and the forge now thinking about the wheat and the chaff. It must be something we all do as we get older. Looking back at my life I can see certain moments when I thought I was in some really bad situations on a personal level. You could say I was lost in the chaff, the part of the wheat plant that is of little use. Then out of seemingly nowhere I would find a kernel of pure whole wheat. The substance that makes the flour which in turn becomes the bread, or pancakes, or cake, or so many other things.
Each one of these little nuggets could have been missed, ignored, or allowed to spoil, it depended on what I chose to do with them. Thankfully I was able to take most of them and turn them into experiences that enriched my life beyond measure. Usually these tidbits would come in the way of a comment made by someone. Not always someone that I thought very highly of. A couple of times they came from people I down right despised, but something made it through.
As far as I know there is no magical instrument that can glean these tiny little pieces of nutrition out for you. That is something you will have to find for yourself. One of the most important lessons that I have learned is to be quiet. Especially when you are being reprimanded or just plain chewed out for something. Then when you can get past the emotion and think about what happened to get you in that situation, you can go over the information. Look at what was said by the person correcting you and be honest with yourself about it. Was the person correct in their assessment? If so what can you take away from the experience to avoid it in the future.
Every time life seems to be beating you down remember it is just the threshing floor, separating the wheat from the chaff. You can get lost in the chaff, or you can take sometime to find the wheat. The choice is always yours. While you may not control what happens to you, you can control how you react to it.