The sulfur recovery from gypsums with a higher H2/CO syngas byproduct and the CO2 abatement via an integrated process involving chemical-looping and iodine–sulfur cycle

Gypsum (GP) by-products are a group of widely sourced sulfur-containing solid wastes and their recycling utilizations are of great significance. This work proposed a new cyclic GP utilization process, achieving both the sulfur recovery and simultaneous value-added syngas byproduct under the restriction of the CO 2 capture. This innovative process integrates the carbon-fueled and calcium-based chemical-looping technology to generate concentrated SO 2 , followed by the recovery of the sulfur to be a concentrating sulfuric acid via the iodine–sulfur thermochemical cycle and finally the CO 2 capture to produce CaCO 3 /(NH 4 ) 2 SO 4 by the use of the in-situ generating calcium adsorbent via the NH 3 -Merseburg process. Its feasibility was thermodynamically and experimentally validated. It’s found that the elevated temperature and the weak reducing atmosphere were conducive to a nearly 100% thermally-decomposed of GP (mainly CaSO 4 ) toward a mixture of CaS and CaO (a ratio in 4:6) and the maximum per pass carbon conversion over 80% using carbon fuels (coal), and the carbon residues can be recovered back to carbon fuel stream. The recovery of I 2 can be achieved through the electrochemical electrolysis method and then recycled. The optimization of heat exchange network results in energy consumption reduction by 79.6% and 75.2% for hot and cold utilities, respectively.