Turbine engine acceleration is a pretty complex process. Simply dumping in more fuel does not assure the desired results.
The fuel controller (MEC, FADEC, whatever...) has been tailored to produce best acceleration on a reasonably healthy engine - it adds a measured amount of fuel to start the accel process, then as RPM and pressures build, a bit more fuel is added, and the cycle repeats... This is to prevent stalls, surges, overtemp, etc.
However - an ice accumulation effectively "redesigns" the aerodynamics so that the amount of fuel the controller thinks correct is now too much! Ergo, stall, lack of acceleration, etc.
A wise pilot can "milk' the throttle through this stage and not demand so much fuel - he's effectively "redesigning" the accel fuel schedule to match the new compressor aerodynamics. Once a high enough RPM is reached, the ice is either melted by heat of compression, or broken loose by centrifugal force, and things return to normal (unless the impact of ice chunks on downstream blades is significant...)
OK?