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Between 0.5 and 2 tons of red mud are generated for each ton of alumina extracted from bauxite by the Bayer process; this can contain as much as 24% TiO2, 43% Al2O3 and 54% Fe2O3. The chlorination of red mud by carbon tetrachloride, which is soon to become an unwanted by-product of other industries, was investigated using a sample from Portovesme, Sardinia. After magnetic separation, chlorination was performed under fluidised bed conditions. The chlorine for the reaction was obtained by cracking of CCl4. The main effects and interactions between CCl4 partial pressure and reaction temperature on titanium recovery were assessed by a full three-level factorial design. Intermediate sampling of TiCl4 during the reaction allowed an evaluation of the effect of time and temperature on the conversion and a kinetic model was proposed. Full recovery of titanium was achieved at CCl4 partial pressure of 0.47 atm and reaction temperature of 700 degrees C., Between 0.5 and 2 tons of red mud are generated for each ton of alumina extracted from bauxite by the Bayer process; this can contain as much as 24% TiO2, 43% Al2O3 and 54% Fe2O3. The chlorination of red mud by carbon tetrachloride, which is soon to become an unwanted by-product of other industries, was investigated using a sample from Portovesme, Sardinia. After magnetic separation, chlorination was performed under fluidised bed conditions. The chlorine for the reaction was obtained by cracking of CCl4. The main effects and interactions between CCl4 partial pressure and reaction temperature on titanium recovery were assessed by a full three-level factorial design. Intermediate sampling of TiCl4 during the reaction allowed an evaluation of the effect of time and temperature on the conversion and a kinetic model was proposed. Full recovery of titanium was achieved at CCl4 partial pressure of 0.47 atm and reaction temperature of 700 degrees C.

Representative samples of a composite mixture of three typical Cu-Zn complex ores from the Cayeli deposit, Turkey, were used for leaching tests in 2.2 M iron III chloride, or 1 M copper II chloride-2 M sodium chloride solution in the temperature range 313-363 K, with and without the presence of an organic solvent for elemental sulphur, such as CCl4. The leaching rates of copper and zinc were quite high in FeCl3 solution and complete recovery of both metals was obtained at the highest temperature with the solvent. In the CuCl2 solution, only 95% extraction was achieved and the positive effect of the solvent was not clearly shown. Kinetic curves of Cu leaching by FeCl3 with CCl4 indicated a chemically controlled reaction; without the solvent, or in CuCl2 media a diffusion controlled reaction seemed to prevail. Values of apparent activation energy were determined and compared with those reported in the literature., Representative samples of a composite mixture of three typical Cu-Zn complex ores from the Cayeli deposit, Turkey, were used for leaching tests in 2.2 M iron III chloride, or 1 M copper II chloride-2 M sodium chloride solution in the temperature range 313-363 K, with and without the presence of an organic solvent for elemental sulphur, such as CCl4. The leaching rates of copper and zinc were quite high in FeCl3 solution and complete recovery of both metals was obtained at the highest temperature with the solvent. In the CuCl2 solution, only 95% extraction was achieved and the positive effect of the solvent was not clearly shown. Kinetic curves of Cu leaching by FeCl3 with CCl4 indicated a chemically controlled reaction; without the solvent, or in CuCl2 media a diffusion controlled reaction seemed to prevail. Values of apparent activation energy were determined and compared with those reported in the literature.

Roasting alunite, KAl3(SO4)2(OH)6, with K2CO3 leads to the formation of K2SO4, thus reducing the amount of pollutant SO3. When a mixture of K2CO3 and alunite with a stoichiometric ratio of 1:5 was roasted at 900 degrees C and the residue leached at 100 degrees C, 80% of the K2SO4 formed was recovered. Roasting temperature, rather than stoichiometric ratio or leaching temperature, was the most important factor affecting potassium recovery. X-ray analysis revealed that the residue from leaching contained up to 80% Al2O3, plus unleached K and the Si present in the ore. A preliminary thermal study showed that the amount of SO3 driven off was limited largely by the reaction with K2CO3. The process would allow the treatment of alunite-polluted kaolin ores without the evolution of SO3, to give a residue suitable for use in the ceramics industry., Roasting alunite, KAl3(SO4)2(OH)6, with K2CO3 leads to the formation of K2SO4, thus reducing the amount of pollutant SO3. When a mixture of K2CO3 and alunite with a stoichiometric ratio of 1:5 was roasted at 900 degrees C and the residue leached at 100 degrees C, 80% of the K2SO4 formed was recovered. Roasting temperature, rather than stoichiometric ratio or leaching temperature, was the most important factor affecting potassium recovery. X-ray analysis revealed that the residue from leaching contained up to 80% Al2O3, plus unleached K and the Si present in the ore. A preliminary thermal study showed that the amount of SO3 driven off was limited largely by the reaction with K2CO3. The process would allow the treatment of alunite-polluted kaolin ores without the evolution of SO3, to give a residue suitable for use in the ceramics industry.

The chlorination of a Venezuelan ilmenite ore with carbon tetrachloride was investigated in an experimental reactor with the principal objective of assessing the feasibility of a process alternative to the traditional route which uses gaseous chlorine and coke. Experimental tests were performed at temperatures in the range 620-700 degrees C and at two different partial pressures of carbon tetrachloride on a concentrate obtained by selective screening and magnetic separation. The concentrate contained about 91 wt% ilmenite. Chlorination provided high extraction yields with nearly 90% recovery of impurity-free titanium tetrachloride. The qualitative trend of the observed kinetic curves was interpreted by postulating a series-parallel kinetic mechanism based on the preferential chlorination of iron as the first stage. Simple kinetic modelling provided an estimate of the apparent activation energy of the process., The chlorination of a Venezuelan ilmenite ore with carbon tetrachloride was investigated in an experimental reactor with the principal objective of assessing the feasibility of a process alternative to the traditional route which uses gaseous chlorine and coke. Experimental tests were performed at temperatures in the range 620-700 degrees C and at two different partial pressures of carbon tetrachloride on a concentrate obtained by selective screening and magnetic separation. The concentrate contained about 91 wt% ilmenite. Chlorination provided high extraction yields with nearly 90% recovery of impurity-free titanium tetrachloride. The qualitative trend of the observed kinetic curves was interpreted by postulating a series-parallel kinetic mechanism based on the preferential chlorination of iron as the first stage. Simple kinetic modelling provided an estimate of the apparent activation energy of the process.

A composite mixture of three typical ores (black, yellow and unaltered) from the Cayeli deposit in Turkey was leached with ferric sulphate solutions under atmospheric pressure, in order to study the reaction kinetics of the copper and zinc dissolution in the temperature range 50-80 degrees C, using a solvent for elemental sulphur such as CCl4. As copper extraction rates were quite low and pressure leaching at high temperatures was clearly necessary, a tentative process for ore enrichment by selective or bulk flotation was then examined. The resulting concentrates were leached in an autoclave at 100-230 degrees C. Good extraction yields were obtained for both metals after a few hours at 140 degrees C., A composite mixture of three typical ores (black, yellow and unaltered) from the Cayeli deposit in Turkey was leached with ferric sulphate solutions under atmospheric pressure, in order to study the reaction kinetics of the copper and zinc dissolution in the temperature range 50-80 degrees C, using a solvent for elemental sulphur such as CCl4. As copper extraction rates were quite low and pressure leaching at high temperatures was clearly necessary, a tentative process for ore enrichment by selective or bulk flotation was then examined. The resulting concentrates were leached in an autoclave at 100-230 degrees C. Good extraction yields were obtained for both metals after a few hours at 140 degrees C.

High temperature roasting of leucite in the presence of CaCl2 gives rise to a reaction that results in almost complete recovery of its potassium content as KCl. A solid residue consisting mainly of anorthite and silica is also obtained. This could be used as raw material for the production of hydraulic binders. The process is of economic interest because of the relatively low temperatures involved and especially the low cost of the reagents employed, since these find no other valid industrial application at present. Potassium chloride, cordierite and silica are obtained if MgCl2 is used instead of calcium chloride., High temperature roasting of leucite in the presence of CaCl2 gives rise to a reaction that results in almost complete recovery of its potassium content as KCl. A solid residue consisting mainly of anorthite and silica is also obtained. This could be used as raw material for the production of hydraulic binders. The process is of economic interest because of the relatively low temperatures involved and especially the low cost of the reagents employed, since these find no other valid industrial application at present. Potassium chloride, cordierite and silica are obtained if MgCl2 is used instead of calcium chloride.