Sales of recovered sulfuric acid require business license, environmental protection procedures, dangerous goods business license and tax registration certificate, as follows:

1. Business license: Enterprises selling recovered sulfuric acid need to have the qualifications of corporate legal persons such as limited liability companies and joint stock companies, and obtain corresponding business licenses.

2. Environmental protection procedures: Enterprises selling recovered sulfuric acid need to have environmental protection procedures, including environmental protection approval, environmental protection acceptance and other related procedures.

3. Holding a dangerous goods business license: sulfuric acid is dangerous goods, and enterprises that recycle and sell sulfuric acid need to obtain a dangerous goods business license, and need to store, transport and use it in accordance with relevant regulations.

4. Possession of tax registration certificate: Enterprises that recycle sulfuric acid for sale need to have a tax registration certificate to declare and pay taxes in accordance with tax regulations.