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A series of fixed and fluidised bed ion exchange column runs were conducted to identify the ability of natural clay minerals, sepiolite and clinoptilolite, to remove ammonia from a contaminated drinking water reservoir. Ion exchange column tests using both fixed and fluidised bed were initially carried out with synthetic water composed of NH4Cl. Breakthrough curves as a function of flow rate, particle size, and initial ammonia concentration reveal that sepiolite does not have as high ion exchange capacity as clinoptilolite but maintains a steady adsorption up to higher bed volumes. The adsorption capacity was modified by using regeneration cycles at both acidic and alkaline pH. Furthermore, fluidised bed runs with clinoptilolite utilising water and air as fluidiser resulted in inferior results compared to those of fixed bed runs. This was respectively ascribed to the presence of ammonia in the circulating water and competition of exchangeable ions released in water and the ability of air to adsorb nitrogen. Tests conducted with natural raw water contaminated with sewage indicated that clinoptilolite adsorbs ammonia the same as the synthetic water. Regenerated clinoptilolite is capable of removing ammonia from both synthetic and actual raw water at a much higher rate than the untreated clinoptilolite.

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In this study, the sulfation roasting characteristics of copper-bearing ore and its flotation products as chalcopyrite concentrate and tailings were investigated in detail. For this aim, the roasting-leaching experiments and thermal analyses were conducted on the samples. As a result of the leaching of sulfated products obtained from the roasting experiments, the maximum Cu extractions were achieved as 94.7%, 99.5% and 82.7%, for run of mine, chalcopyrite concentrate and the flotation tailings, at the roasting temperatures of 550, 650 and 525°C, respectively. It was also found that the copper extractions began to decrease owing to decomposition of copper sulfates above these temperatures. It was indicated that the decomposition temperature of copper sulfates differ for each samples. On the other hand, thermal gravimetric and differential thermal analyses were subjected to identify the thermal behaviors of the samples. The results showed that the formation of metal sulfates occurred in a wide temperature range (394-650°C) for chalcopyrite. On the contrary, copper sulfation reactions took place at narrow temperature ranges of 450-560°C and 480-550°C for the run of mine ore and the flotation tailing, respectively. Figure 5. Differential thermal analyses (DTA) and thermal gravimetric (TG) curves for run of mine ore (a) and flotation tailing (b). Asia-Pacific Journal of Chemical EngineeringROASTING OF COPPER-BEARING MATERIALS 371