Is there anything else associated with the mixer process, like a jet-wet blower/water solenoid valves for making polymer, or conveyor system? Multiple sources of power? If no and no, a local lockable disconnect should suffice. Locking out the MCC is not a difficult process for a non electrician, tho there's always the chance of locking out the wrong equipment or shutting down something that needs to be running.
Since adding a local disconnect will slightly change the maintenance process, I'd also make sure the process for raising the blades has sufficient measures/procedures to lock them in place for cleaning so that they cant move/fall on the operator during cleaning, and if they need to rotated manually for cleaning, there is an approved procedure for doing that as well. Any other processes (automatic fill valves, etc.) for the tank should be isolated and LO/TO, and if it's a confined space and/or there is engulfment or hazardous atmospheric potential, now may be a good time to review those too.
Electricians do it until it Hertz!