The phrase "grinded away" essentially means to work hard or persistently towards a goal, or to continue doing something despite difficulty or resistance. However, there are various synonym options to replace this phrase, including "labored diligently," "persevered," "toiled tirelessly," "grappled tenaciously," and "endured steadfastly." Each of these options conveys a similar meaning to "grinded away," but with a slightly different connotation or nuance. Ultimately, the right synonym choice will depend on the context in which the phrase is used and the tone or mood that the author wishes to convey.