발간논문

Home > KJMM 논문 > 발간논문

The fritting characteristics of Korean zircon sand in the caustic treatment have been studied as a function of caustic-to-zircon sand ratio, fritting temperature, fritting time and particle size of ore. For a caustic-to-zircon sand weight ratio of 1.2 to 1.4, a furnace temperature of 1000℉ to 1100℉ and 15∼60 minutes of fritting time, it was found that 80∼95% of zircon sand converted to acid-soluble sodium zirconates, The rate of fritting reaction for the low caustic-to-zircon sand ratio depends on the particle size and uniformity. When the caustic-to-zircon sand ratio is lower than 1.2, the coarse and uniform sand reacts more efficiently in a shorter fritting time than the finer or nonuniform sand. The low caustic-to-zircon sand ratios and the short fritting time have proved adequate for converting the sand to a granular product which can be conveniently leached and treated for the recovery of zirconium.

keyword :

The polarograms were prepared to investigate the electrode kinetics concerning with the formation of electrolytic manganese dioxide, by using the cell of platinum point anode, platinum crucible cathode and manganese sulfate solution. And further, the current potential curves of electrolysis were made by the galvanostatic method. The experimental results indicated that the electrode reaction was single oxidation process and at least 90℃ of bath temperature was necessary to restrain the evolution of oxygen. The parameters of electrode reaction, transfer coefficient and exchange current, were 0.098 and 3.0×10^(-4) amp per ㎠ respectively. As a result, the rate determining process was not the charge transfer but the hydrolysis process forming the manganese dioxide. The current efficiency become higher as the Mn^(++) concentration increased and when current density was lower than 1 amp per d㎡. The results obtained in the electrolytic oxidation of refined MnSO₄solution which was prepared from domestic Rhodochrosite ores as a starting material reached to the same conclusion as was seen in polarographic studies.

keyword :

For the time being, many foundry shops in our country have been used naturally bonded clay sand as a molding sand. It is difficult to improve the quality of casting with the naturally bonded clay sand mold, compared with synthetic sand added bentonite as a binder. Most of the foundry shops in the developed country have been used synthetic molding sand for about 30 years. Recently, some foundries in our country where produce malleable cast iron have been used synthetic molding sand and other foundry shops are planning to use it to decrease casting defects. It is important and necessary to study mechanical properties of molding sand added bentonite as a binder in the foundry industry in our country. In this study, the mechanical properties of synthetic molding sands with the various amount of domestic bentonite were examined and tested.

keyword :

keyword :

keyword :