Are bank interests permissible if the intention is investment, and what is the ruling on interests acquired previously if they were unlawful, and are Islamic banks permissible, and how do they operate?

Usurious bank profits are forbidden, and one must dispose of them by spending them on the welfare of Muslims. It is permissible to deal with Islamic banks that adhere to the rulings of Sharia (definition) in investing and developing money. However, it is not permissible to deal with banks that claim to be Islamic but do not abide by the rulings of Sharia.