How will Hashem refine them?
Rashi: Via afflictions. Radak - they will show whether the dross will remain, or if they will repent to become choice silver due to the afflictions.
Why does it say "Tzorfam u'Vechantim"?
Malbim: After refining them in fire to remove the dross, I will test if they were refined properly.
What is the meaning of "Mipnei Bas Ami"?
Rashi citing Targum Yonasan: In front of the sins of Keneses Yisrael.
Radak: How can I not refine them because it is Bas Ami? I cannot leave them in their evil, and they are called My nation.
Malbim: I do not know how to do that they will be clean from all dross, for also after refining, i.e. fire and afflictions, they are still full of dross and filth. Therefore, I need to test them and refine them time after time.
