Abstract: In this paper, kinetics of reductive leaching of manganese dioxide ore by ferrous ion in sulfuric acid media has been examined. Experimental results show that increasing temperature from 20 to 60 °C and decreasing ore particle size from −16+20 to −60+100 mesh considerably enhance both the dissolution rate and efficiency. Molar ratios of Fe2+/MnO2 and H2SO4/MnO2 in excess to the st...

The main objective of this work was to assess the optimization of Fe and Cu bioleaching from converter slag using Acidithiobacillus ferrooxidans. Important parameters that contribute to the bioleaching process include initial pH, initial Fe2+ concentration and pulp density. In order to optimize these parameters, the response surface methodology (RSM) was applied. The maximum...

The third generation partnership Project’s (3GPP) spatial channel model (SCM) is a stochastic channel model for MIMO systems. Due to fixed subpath power levels and angular directions, the SCM model does not show the degree of variation which is encountered in real channels. In this paper, we propose a modified SCM model which has random subpath powers and directions and still produces Laplace s...

nowadays we know effective supply chain management a key to business success. therefore, supply chain managers use many practices for scm effectiveness and many tools as their enablers. nevertheless, literature about causal relations between sc enablers and scm practices and performance is scarce. this study reports a cognitive mapping of causal relationships between scm practices, sc enablers ...

Vanadium is distributed widely and scarcely (150 ppm) on the earth. Its major applications are in steelmaking, dye-production and catalyst-fabrication industries. With the ever-increasing demand for this metal, secondary resource-exploitation of such waste materials as spent catalysts is recommended. Many reactions are involved in vanadium-extraction from these resources. Since roasting in comp...

In this research work, the dissolution of chalcopyrite was investigated under atmospheric pressure, with sulfate media at low temperatures, in 30°C to 50°C. In the galvanic interaction between chalcopyrite and pyrite, pyrite is used as a leaching catalyst. Effects of different parameters such as temperature, stirring speed, pyrite to chalcopyrite ratio, particle size, and solution potential wer...

Globalization of the economy, e-business, and introduction of new technologies pose new challenges to all organizations especially for small and medium enterprises (SMEs). In this scenario, successful implementation of supply chain management (SCM) can give SMEs an edge over their competitors. However, SMEs in India and other developing countries face problems in SCM implementation due to lack ...

The direct sulfation of three high purity Iranian limestones and one precipitated calcium carbonate from different sources, containing more than 97 % CaCO3, were studied in a specially designed fixed bed reactor under atmospheric pressure, in the presence of excess CO2 to prevent decomposition of CaCO3. Experiments were carried out over a range of particle s...