MOLTEN SALT OXIDATION: A REASSESSMENT OF ITS SUPPOSED CATALYTIC MECHANISM AND HENCE ITS DEVELOPMENT FOR THE DISPOSAL OF WASTE AUTOMOTIVE TIRES

摘要

Molten Salt Oxidation, MSO, is a thermal, non-flame process that destroys completely organic compounds and retains non-volatile inorganic species in the molten salt. Hydrocarbons are converted to CO_2 and steam but rubber tires leave much unreacted carbon. In the EU tire burial will soon be prohibited. MSO uses a carbonate at up to 1200℃ with air constantly bubbling through it and into which waste is added below the melt surface. However, the carbonate is not a catalyst, it dissolves oxygen chemically, forming peroxide and superoxide species. But nitrate is a catalyst, increasing the active species, via recycled nitrite. For complete oxidation of used automobile tires devulcanisation was first required. We used a phosphorus compound not used before. Molten carbonate with 5% nitrate now completely oxidized scrap rubber, leaving no carbon in the melt. The off-gases were CO_2, H_2O, N_2 and excess O_2. More tests are needed to optimize the system.