Method for reducing and decomposing phosphogypsum by sulfur

Abstract

The invention discloses a method for reducing and decomposing phosphogypsum by sulfur, which comprises the following steps: putting the phosphogypsum into a reactor, and raising the temperature to between 500 and 900DEGC for preheating for 10 to 30 minutes at an inert atmosphere; introducing gaseous sulfur in a molar percentage of 10 to 50 percent to perform reduction reaction with the phosphogypsum for 1 to 2 hours; grinding obtained a calcium sulfide block, and uniformly mixing the ground calcium sulfide with the phosphogypsum in a molar ratio of 1-1.5:3; sintering at a temperature between 1,000 and 1,400 DEG C for 0.5 to 3 hours at a non-oxidizing atmosphere; and taking CaO in the obtained solid slag as a cement clinker for cement production, taking the generated tail gas SO2 as a raw material gas for producing sulphuric acid. The reduction rate of CaSO4 is high, the decomposition ratio of the phosphogypsum can reach over 98 weight percent, the desulfurization ratio of the phosphogypsum can reach over 95 weight percent, and the method has the advantages of low energy consumption, simple and mature process, short production period, easy control and convenient promotion.

Description

technical field [0001] The invention belongs to the technical field of reducing and decomposing phosphogypsum, and in particular relates to a method for reducing and decomposing phosphogypsum with sulfur. Background technique [0002] Phosphogypsum is the solid waste discharged during the production of wet-process phosphoric acid. Generally speaking, about 5-6 tons of phosphogypsum is produced for every 1 ton of phosphoric acid produced, and the actual amount is about 7.5 tons. The concentration of phosphorus compound fertilizer increased significantly. However, the current resource utilization of phosphogypsum is not satisfactory. It is known that the effective utilization rate of phosphogypsum in the world is only about 4.5%. By the end of the "Eleventh Five-Year Plan", the annual discharge of phosphogypsum in my country will exceed 50 million tons, and the cumulative stockpiles have exceeded 120 million tons. Stacking phosphogypsum not only takes up a lot of land, but a...

AI Technical Summary

Problems solved by technology

[0005] Although the above method of reducing and decomposing phosphogypsum to produce sulfuric acid co-production cement has made full use of prohibited substances and wastes in the coal industry to reduce and decompose phosphogypsum, and the decomposition rate and desulfurization rate are relatively high, but there are some or other defects to varying degrees. Problem: Since the traditional reaction mechanism of reducing and decomposing phosphogypsum is a solid-solid reaction, the reaction temperature is high, which not only increases energy consumption, but also has a cumbersome process, and the decomposition rate and desulfurization rate of phosphogypsum are low

Or due to the high requirements for raw material pretreatment and ingredients, the process flow becomes more cumbersome, which is not suitable for large-scale industrial production