Environment-friendly production process for producing sulfuric acid by using waste sulfuric acid by virtue of sulfur reduction

The invention relates to an environment-friendly production process for producing sulfuric acid by using waste sulfuric acid by virtue of sulfur reduction. The production process comprises the following steps: firstly concentrating waste sulfuric acid until the content of sulfuric acid is above 80% and then adding sulfur and waste sulfuric acid at a ratio of 1: (5.5-6.5) into a reactor, heating to 200 DEG C-250 DEG C, reducing the sulfuric acid to produce sulfur dioxide, cooling the produced sulfur dioxide by virtue of circulating water in a heat exchanger, removing high-boiling-point impurities and then cooling with cold brine for liquefying sulfur dioxide to remove non-condensable gas, and then vaporizing, liquefied sulfur dioxide, drying sulfur dioxide gas with concentrated sulfur dioxide to remove moisture in sulfur dioxide and then producing sulfuric acid according to the conventional production process, such as catalytic oxidation and absorption. The process and device are simple, the heating temperature is low, the energy consumption is low, the production cost is reduced, the problem of difficulty in processing of waste sulfuric acid is not only solved, and the production process further provides a novel idea for solving the problems of high temperature and high energy consumption of the conventional production process of sulfuric acid and has great innovation and universal applicability for the preparation process of high concentrated sulfuric acid.