This can be done through electrolysis. Electrolysis is the separation of a substance into two or more substances that may differ from each other and from the original substance by passing an electric current through a solution that contains ions.
In the case of copper, we use a copper (II) sulphate solution which we put in a large beaker. The impure copper will be used as the positive electrode (anode) and for the negative electrode (cathode) will be a bar of pure copper.
When the electric current is switched on, the bar of pure copper which is the cathode increases greatly in size as copper ions leave the anode of impure copper and attach to the cathode. The anode becomes smaller and smaller as it loses copper ions until all that is left of it is impurities in form of a sludge beneath it.