Document jyLJZzy9O1wQgo0LvaaEjr8VZ

Roesch et al is an interesting summary of other methods. - Supporting documentation The cement kiln PFAS burning trials reports and results are subject to commercial sensitivities, however the critical aspects can be shared and are in my presentations. - How the PFAS foams concentrates and firewaters are handled in practice in cement kilns The concentrates or wash-waters can be introduced into either the calciner or the main burner. However, the water content can disrupt flame temperatures. So the best method for introduction is with it mixed in at low concentrations into "alternative fuel" (waste oil) that is fed in as normal fuel. The trials in Queensland ran quantities of PFAS at up to 0.5% fluorine concentration at a rate of up to 1 tonne per hour. This equates to 5kg of fluorine per hour. However, the kiln also destroys up to 325 kg of fluorine per hour in spent aluminium cell carbon (2.5 tonnes/hr) with no significant emissions of HF or PFAS (~0.05 mg/Nm3). So our 5kg per hour of PFAS fluorine with a destruction efficiency of 98% set in a licence condition is probably insignificant. PFAS can only be introduced when the kiln operating conditions are stable. - Cost of the incineration per kg of concentrate/firewater Cement kiln cost for destruction is reputedly $6.50/L (~4). Plasma arc destruction was about $18.00/L (~11). For dilute PFAS it is suggested that PFAS be concentrated by ion exchange resins, Perfluorad or GAC. - Air emission measurements results analysis of the cement kiln output products No PFAS were found in air emissions or the cement clinker in the trials. The 750:1 excess of calcium to fluorine and very long residence times progressively locks up the fluorine. HF measured at about 1/1000 of the licence limit of 50 mg/NM3 @7% O2 regardless of whether there was 5kg PFAS or 325 kg of other fluorine inputs or not. Destruction efficiency was PFOS DRE = 99.99993%, PFOA DRE = 99.99975%, PFHxS DRE = 99.99936%. - Enforcement: is there a maximum concentration of fluorinated compounds in the kiln fumes PFAS analysis for the stack gases is required periodically. No PFAS limits have been set. Monitoring assumes that HF will manifest first. - Any effect of the CaF2 in the cement klinker? The cement clinker product quality is unaffected by the CaF2 trace content, this is a normal part of cement production from fluorine in feedstocks like limestone. - Overall assessment of the technique by the authorities Overall the co-processing of PFAS in cement kilns is favoured as the safest and most sustainable option: - Zero extra energy is required above that for normal cement production (some reduction in fuel use is even possible). - Normal kiln conditions provide very large safety margins in temperature and residence times. - Temperatures far exceed those needed for complete destruction (800-1600C). - Calcium catalyses PFAS destruction at low temperatures (from 350C) 1100C Is not