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Carbohydrates such as glucose, lactose and whey were used as reducing agents in the leaching of manganiferous ores from an Italian mine to simulate, in the last two cases, the possible reuse of cheese manufacturing plant waste. Leaching tests with glucose were performed in both a stirred-tank reactor (STR) and in fixed-bed column. A process flowsheet for manganese sulphate production is proposed., Carbohydrates such as glucose, lactose and whey were used as reducing agents in the leaching of manganiferous ores from an Italian mine to simulate, in the last two cases, the possible reuse of cheese manufacturing plant waste. Leaching tests with glucose were performed in both a stirred-tank reactor (STR) and in fixed-bed column. A process flowsheet for manganese sulphate production is proposed.

Biosorption of heavy metals is one of the most promising technologies for waste water treatment. An Arthrobacter sp. biomass was characterised in terms of ionic exchange capacity and acid-base titration and tested as a Cu2+, Cd2+ and Fe3+ biosorbent at different equilibrium pH values and biomass concentrations. Experimental data showed that biosorption equilibrium was not reversible under the conditions examined. The biomass tested gave better results than those for kaolin in the 0-200 ppm range of metal concentrations., Biosorption of heavy metals is one of the most promising technologies for waste water treatment. An Arthrobacter sp. biomass was characterised in terms of ionic exchange capacity and acid-base titration and tested as a Cu2+, Cd2+ and Fe3+ biosorbent at different equilibrium pH values and biomass concentrations. Experimental data showed that biosorption equilibrium was not reversible under the conditions examined. The biomass tested gave better results than those for kaolin in the 0-200 ppm range of metal concentrations.

The autocatalytic effect of Fe2+ in oxalic acid leaching of kaolin was studied in order to define the mechanism governing the dissolution of iron from a potentially commercial Italian kaolin. Leaching tests in the pH range 0.5-1.0 were carried out with sulphuric acid with and without the addition of oxalic acid. The catalytic effect of Fe2+, although shown, was found not to be so large as reported by other researchers, possibly as a result of the chemical and mineralogical characteristics of the ore studied., The autocatalytic effect of Fe2+ in oxalic acid leaching of kaolin was studied in order to define the mechanism governing the dissolution of iron from a potentially commercial Italian kaolin. Leaching tests in the pH range 0.5-1.0 were carried out with sulphuric acid with and without the addition of oxalic acid. The catalytic effect of Fe2+, although shown, was found not to be so large as reported by other researchers, possibly as a result of the chemical and mineralogical characteristics of the ore studied.

Laboratory studies were carried out on a refractory gold-bearing stibnite ore from South America to develop an innovative process to include alkaline leaching pretreatment prior to conventional cyanidation-electrowinning. After leaching with a solution of sodium sulphide (Na2S) and sodium hydroxide (NaOH), the antimony was recovered as high-grade metallic antimony by electrodeposition; antimony recovery was about 75%. It was found that the chemical pretreatment improves gold extraction and reduces reagent consumption; gold recovery by cyanidation-electrowinning increased from 35% to 80% after pretreatment. A complete flowsheet with low environmental impact is proposed., Laboratory studies were carried out on a refractory gold-bearing stibnite ore from South America to develop an innovative process to include alkaline leaching pretreatment prior to conventional cyanidation-electrowinning. After leaching with a solution of sodium sulphide (Na2S) and sodium hydroxide (NaOH), the antimony was recovered as high-grade metallic antimony by electrodeposition; antimony recovery was about 75%. It was found that the chemical pretreatment improves gold extraction and reduces reagent consumption; gold recovery by cyanidation-electrowinning increased from 35% to 80% after pretreatment. A complete flowsheet with low environmental impact is proposed.

A shrinking core model with variable activation energy was found to fit the experimental data for manganese extraction yields versus leaching time for an Italian manganese oxide ore. The model finds a physical confirmation both in the complex reactions that take place during leaching and in the different reactivities and accessibilities of the mineralogical forms present in the ores. A non-linear regression analysis was carried out to estimate the adjustable model parameters and a statistical analysis was used to evaluate the significance of the estimated values., A shrinking core model with variable activation energy was found to fit the experimental data for manganese extraction yields versus leaching time for an Italian manganese oxide ore. The model finds a physical confirmation both in the complex reactions that take place during leaching and in the different reactivities and accessibilities of the mineralogical forms present in the ores. A non-linear regression analysis was carried out to estimate the adjustable model parameters and a statistical analysis was used to evaluate the significance of the estimated values.

Five ores from mines in Italy and Greece, including high-grade and low-grade ores rich in Al as well as magnetic separation feed and waste, were characterised by X-ray diffraction and leached in a sulphuric acid medium with a carbohydrate reducing agent. Manganese contents of the ores ranged from 17.1 to 38.8%. The leaching showed satisfactory selection of Mn over other metals such as Al, Si and Na, with Mn recoveries of 63.4, 79.7, 94.8, 99.7 and 100%. An increase was also noticed in a general amorphous phase within the ores; this might be usefully exploited by producing light construction materials from the inert leached waste., Five ores from mines in Italy and Greece, including high-grade and low-grade ores rich in Al as well as magnetic separation feed and waste, were characterised by X-ray diffraction and leached in a sulphuric acid medium with a carbohydrate reducing agent. Manganese contents of the ores ranged from 17.1 to 38.8%. The leaching showed satisfactory selection of Mn over other metals such as Al, Si and Na, with Mn recoveries of 63.4, 79.7, 94.8, 99.7 and 100%. An increase was also noticed in a general amorphous phase within the ores; this might be usefully exploited by producing light construction materials from the inert leached waste.