Selecting and Testing of Cement-Bonded Magnetite and Chalcopyrite as Oxygen Carrier for Chemical-Looping Combustion

Combining iron and copper ores can generate an oxygen carrier that has a synergic effect of high temperature resistance and high reactivity. In this work, typical cements available in the market were studied as binders to bind magnetite and chalcopyrite to develop a suitable oxygen carrier for chemical-looping combustion (CLC). A first selection step suggested that an aluminate cement, namely CA70, could favor the generation of oxygen carrier particles having good crushing strength, good particle yield, and high reactivity. The CA70-bonded oxygen carrier was then subjected to cyclic tests with CH4, CO, and H-2 in reduction and in air oxidation at temperatures of 850, 900, and 950 degrees C with gas concentrations of 5, 10, 15, and 20% in a batch-fluidized bed reactor. The increase in temperature promoted the fuel conversion. At 950 degrees C, the conversions of CH4 and CO reached up to 80.4% and 99.2%, respectively. During more than 30 cycles, the oxygen carrier kept a similar reactivity to the fresh carrier and maintained its composition and physical properties. The oxygen transport capacity was maintained at 21-23%, and the phases were CuO, Fe2O3, Al2O3, and minor CaS. In the used sample, some grains were observed, but the morphology was not greatly changed. Agglomeration was absent during all the cycles, except for the deep reduction with H-2.

Automated summary

By using aluminate cement as the binder, a suitable oxygen carrier for chemical-looping combustion (CLC) was developed. The oxygen carrier showed stable reactivity, maintained its composition, and did not experience agglomeration during cyclic tests.