Rough situation at work. Oil and gas is a traditionally white, male, conservative dominant industry and my company just got named as one of the least "diverse" companies on the S&P 100. I'm a white male, so hooray for me, but a black guy in my group (we'll call him Lamont) has to sit next to a couple of racists.
Lamont has a recording on his phone of two guys in our group going off in an adjacent cube about a Mexican co-worker, going off on black people (several n-bombs), etc. After he made the recording several months ago he went to HR and our boss (Lamont and the racists report to the same guy). Boss' solution was for them to write a letter saying they were sorry.

Lamont is afraid of pushing the issue with HR as he's a younger guy and the two racists have been in the business for 25+ years and Lamont is afraid of being blackballed (I know).
Evidently things flared up again today and Lamont pulled me aside and asked if I wanted to listen to the recording. I do not. I started tearing up when I heard the story from someone else, so no way I could handle hearing it myself. I explained this to him and told him that I would help him any way I can, but I really didn't have any other advice other than "you have to take care of yourself."
I know things in this situation suck 100x worse for Lamont than they do for me, but I've no clue what to do here.