Open loop is fine but not back into the engine, I would probably call it a closed loop system if your keeping it in the engine. Open loop to me would be when venting to atmosphere.
•one way to keep it closed loop and still keep the intake clean, is link a catch can into the breather pipe that runs to the intake pipe. It then allows the gases to condense into liquid in the catch can and then drop to the bottom of the catch can, this way keeps a vacuum from the intake pipe which helps draw the gases out of the rocker cover. 2 things you would need are, a wire wool type material in the catch can though so it traps the gases, and a one way valve/check valve on the pipe to the intake (after the catch can) to stop any air being pushed into the catch can.
•or the other way is just run the breather pipes to the catch can and vent it to atmosphere. This way on a drift or race car. Road car probably the other way.