What is the ruling on working in a place where there is no mosque, and is it permissible to pray individually?

It is permissible to work in a place where there is no mosque, as the presence of a mosque is not a condition for the permissibility of work. If the worker is with one or more persons, they should pray in congregation at the workplace. If the worker is alone, he should pray by himself, and his prayer is valid. He will be rewarded with the reward of congregational prayer if Allah knows the sincerity of his intention and his determination to achieve that reward, and that nothing prevented him from it except the absence of a congregation to pray with.