What is the ruling of Islamic law regarding a husband's money earned from his work in a company that produces foods, some of which contain alcohol, knowing that he has mixed this money with money from his other work?

It is not permissible for a Muslim to work in the alcohol industry. You have done well in advising your husband to leave this job. Continue to advise him and seek support from fatwas that endorse this. If he does not respond, you have the right to demand lawful maintenance or divorce. Since he has been convinced, his remaining contact with the job for renewing documents does not affect the lawfulness of his income. As for unlawful money mixed with lawful money, it must be disposed of by spending it on the poor, the needy, and public welfare.