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Physical properties 13 Chemical properties 15 Reaction Mechanism 16 Fused Salt Chlorination of Other Metals 17 Titaniferrous ores 18 Oxide chlorination study 18 SLURRY REACTION CHARACTERSTICS 20 Carbochlorination of a Pure Oxide 20 Mixed Oxides 26 EXPERIMENTAL EQUIPMENT AND PROCEDURES 29 Aluminum Chloride Purification 29 Fly Ash Solubility Experiments 31 Fused Salt Chlorination Experimental Design 33 Chlorination Equipment 34 ill Reactor 34 Metal chloride condensers 42 Noncondensable gas analysis 43 Chlorination Experimental Procedure 47 Analytical Procedures 50 Analysis of slurry samples 50 Chemical analysis 50 Particle size analysis 52 Reactant Characteristics 53 Alumina 53 Fly ash 55 Carbon sources 55 RESULTS AND DISCUSSION 58 Alumina Chlorination Screening Study 58 Experimental procedure 59 Alumina loading and melt composition effects 60 Carbon loading and chlorine flow rate effects 64 Temperature effects 65 Summary Temperature Dependence Reaction profiles Arrhenius analysis Mechanism versus temperature Chlorine side reactions Process considerations Chlorine sparger plugging Summary Mechanism Experiments 81 Coke impurities 81 Alumina-carbon prechlorination reaction 83 Carbon prechlorination 88 Summary 91 Carbon Loading and Surface Area Effects 91 Carbon particle reaction 97 Summary 101 Reaction Rate Versus Stirrer Speed 102 iv Proposed Reaction Mechanism 104 CO formation 108 Summary 109 Effect of NaCl-AlClg Melts on Fly Ash 109 Summary 114 Fused Salt Chlorination of Fly Ash 114 Major component chlorination 115 Minor component chlorination 122 Reactivity of mineral phases in fly ash 125 SEM micrographs 127 Comparison to gas-solid chlorination 132 FUSED SALT CHLORINATION PROCESS 135 Fused Salt-Gas-Solid Reaction Comparison 135

Reaction mechanism and rates were determined from 803 to 1,073 K for the carbochlorination of AI,O, and of Al, Si and Fe-mixed oxides using CI, and C slurried in a stirred melt of NaCI-AICI,. Alumina chlorination rates of 0.33-2.0 x kmol/s were obtained using C:melt weight ratios between 1:21 and 1:42. The reaction rate was proportional to C loading at temperatures below 923 K, while gas-liquid mass transfer was rate-controlling at higher temperatures. Carbochlorination of the combined oxides in coal fly ash at 923 K and oxide conversions less than about 50% was also gas-liquid mass-transfer-controlled. At higher conversions, dissolution became the rate-controlling factor. A 40% (molar) AICI, melt was more effective than a 48% AICI, melt for the selective chlorination of AI,O, over SiO,.

Carbochlorination of the metal oxides in fly ash by suspending the solid reactants in a NaCl-AlCl3 melt at 530–850°C and then sparging chlorine into the melt has been investigated. A mechanically agitated, semi-batch reactor was used to test the effects of temperature, oxide and carbon loading, salt composition and gas flow on the reaction rate. The process was modeled using the carbochlorination of pure alumina, the rate of which was found to be chemical reaction controlled at temperatures below about 650°C and gas-liquid mass transfer controlled at higher temperature. The carbochlorination rate of the mixed oxides in coal fly ash was also mass transfer controlled at higher temperatures when aluminum recoveries were less than about 50%. At higher aluminum recoveries, the overall rate was limited by the rate of ash dissolution into the melt.