Super King Air 200
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 7.0
Training / Qualification; Situational Awareness; Confusion; Communication Breakdown
ATC Issue All Types; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance
Airspace Structure; Company Policy; Human Factors
The aircraft was planning the RNAV Approach. We had just split the sector and there was confusion as to which frequency the aircraft was on. The aircraft was close to the Initial Approach Fix and asked for lower. We assigned 9;000 feet and turned them 30 degrees right to give an appropriate intercept angle. We left the aircraft on the heading just a minute too long. We climbed the aircraft to 10;000 feet for terrain and turned them back to the fix; but while the aircraft was turning they got into a 10;000 feet terrain box while at 9;500 feet.  A low altitude alert was then issued. On the job training was in progress.
ZLC ARTCC Controller reported due to a communications error after de-combining sectors an aircraft was left on a heading too long and flew below the Minimum Vectoring Altitude.