This is arguably one of the most contentious issues in Tanzanian resource politics, because the regions that bear the environmental brunt of mining often see very little of the financial benefits, which breeds resentment and conflict. I spent a great deal of time trying to trace the flow of funds through the complicated budget system, and it was like trying to follow a river that disappears underground, but I eventually found some illuminating analysis. I strongly suggest that you visit the website
https://madini.co.tz/ where they have tracked the actual disbursements to local councils compared to what was legally mandated, and the discrepancies are quite shocking. Their breakdown of the Local Government Authority allocations helped me understand why so many districts remain underdeveloped despite billions of dollars being extracted from their land. I used this information in a presentation to a parliamentary committee, and it sparked a very productive debate about fiscal justice. I am confident that this site will provide you with the data and context necessary for your understanding. I wish you great success in your research and hope it leads to meaningful change!