(Pro 25:4 KJV) Take away the dross from the silver, and there shall come forth a vessel for the finer.
In reality I know little or nothing about refining metals. I read a lot and pick up snippets but who knows if they are correct, but that having been said....
My impression is that refining silver is not a one step process or was not in the days of Solomon. My picture is a crucible of molten silver that is held over the fire and the impurities slowly rise to the surface. They are skimmed off and the heating continues. The longer it takes the more pure the silver becomes. There might be modern techniques that speed the process but Proverbs is drawing a picture in BC technology.
Becoming what God wants us to be is often a painfully slow process. I have heard of people who were delivered from addictions in a moment. I have heard of others who had to go through the withdrawal process. Why? I don’t know but the cleansing was necessary.
So? If God removes something from your life in a moment, rejoice. If it is a painful plod, rejoice. Keep in mind that God knows best what will work in your life and how to get you there. It is part of living by faith.