Meaning of high-grading in English:

high-grading

Pronunciation /ˌhʌɪˈɡreɪdɪŋ/

noun

US Mining
  • The action or practice of stealing ore, especially high-grade gold ore, from a mine. Also: the practice of stripping the high-grade ore from a mine, leaving the lower-quality ore behind.

Origin

Early 20th century; earliest use found in Anaconda (Montana) Standard. From high-grade + -ing.