발간논문

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The solvent extraction of copper by LIX84 in kerosene was investigated to separate and recover copper from solution containing copper, nickel and cobalt leached from matte, intermediate product of manganese nodules. Copper, nickel and cobalt concentrations in synthetic solution were 12 g/ℓ, 15 g/ℓ and 2 g/ℓ respectively, and pH was 4.0, which is similar to those of real leaching solution. The effects of time, pH, extractant concentration and temperature on extraction ratio were investigated and scrubbing and stripping conditions are also tested. The extraction efficiencies of copper, nickel and cobalt were respectively 78.2%, 2.5% and 0.0% with 30% LIX84, O/A 1.0 and equilibrium pH of 1.09, and were increased to 98.9%, 12.3% and 9.5% with controlling equilibrium pH to 2.1. The McCabe Thiele diagram predicts that at an O/A ratio of 1, pH 1.15 with 30% LIX84, three stages are needed to extract the copper concentration from 12.0 g/ℓ in the feed solution to 0.2 g/ℓ in the raffinate, with a copper extraction of over 98%. On the other hand, two stages are required to strip over 95% copper from the solvent (12.0 g/ℓCu) at O/A ratio of 2 with 180 g/ℓH₂SO₄. Nickel (0/46 g/ℓ) in the solvent could be scrubbed at A/O ratio of 1 with 2.0 g/ℓ H₂SO₄.

keyword : Solvent extraction, LIX84, Copper, Nickel, Cobalt, Manganese nodules, Matte, Leaching solution

A SHTT (single hot thermocouple technique) has been applied to measure crystallizing temperature and crystallizing rate of molten mold fluxes. It was possible to measure the crystallizing temperature and crystallizing rate of the commercial mold flux using a SHTT reliably, while the crystallizing temperature from DTA and the breaking temperature showed poor reliability. In SHTT, crystallizing temperature was measured at the continuous cooling speed of 100 K/min, and crystallizing initiation time at 1050℃. The crystallizing initiation time generally decreased for the mold flux of higher crystallizing temperature, and there is good interrelationship (R²=0.9588) between two. It is concluded that the SHTT should be considered as the method of quantifying the crystallization behaviors during continuous casting of steel.

keyword : Mold flux, Crystallization, Hot thermocouple, DTA, Cuspidine, Breaking temperature, Continuous casting, Steel

The metallurgical microstructure of a sword and a spear excavated from the Hwangnam Great Tomb was examined in an effort to understand the iron technologies applied in the manufacturing of Silla iron articles. The development and peculiar distribution pattern of such diverse microstructures as martensite, pearlite and ferrite were found to have crucial information about ancient iron-smelting, steel-making and heat-treatment. It is suggested that the low temperature reduction process was in use at the time for producing bloomery iron of low C content, which was supplied as an input material for shape-forging. The strengthening of iron articles was found achieved in two steps, i.e., first by increasing the C content in a carburization treatment and then by quenching with its effect strictly confined in a specific part requiring high strength in service. The Silla iron technology as observed in the microstructure of the present artifacts may be characterized by the unique engineering procedure occurring in the order of shapeforging, steel-making and heat-treatment.

keyword : Hwangnam great tomb, Iron artifact, Microstructure, Silla iron technology