What I found is that the workers are not satisfied with their wages
Is this ever not found in a company? Who does not think they should get a raise?
So what would be the best way to approach this problem from a human resources perspective? The most logical thing would be to work on issues related to emotional salary, but I would like to hear other opinions.
Emotional salary works when the trade off is being happier at work instead of buying a new boat. The challenge with minimum wage is that for many, it is a survival wage, so having a nice Christmas card isn't a motivator.
You do not state your industry, but figure out what types of people end up working at the particular company. Are they young single uneducated men? Single moms with children? Seniors looking for something to do? Felons stuck in the job? Students at the local university?
There are lots of low-cost perks which could be offered. Moms could be given more flexibility. Seniors could be offered chairs if they are at the cash register. Felons could be offered easy access to a reference or flexibility to see their parole officers (this is an actual problem for many of them who work regular hours as often they must check in during regular hours). Students could be given scholarship lists.
Figure out why your workers work there and find a perk which benefits them.