No abstract

A direct reduced iron (DRI) was prepared using iron concentrate pellets and a coal as a reductant through three stages, namely, the first: iron concentrate pellets were dried by slow heating at 150°C to remove water content, the second: they were heated at 1,200°C to reduce magnetite into hematite which was treated in two different conditions, namely by oxygen and without oxygen injections; and the third: they were reduced in an atmosphere of CO/CO2 at various temperatures of 950-1,200°C. In this reduction process of iron oxide would be reduced by CO to metallic iron (Fe). The experimental results showed that the metallization without oxygen injection produced the best metallization at 1,100°C and the ratio of carbon/iron (FC/Fe) of 0.52 to result 84.54%, contained 74.68% Fe and 88.34% Fetotal. The metallization by oxygen injection produced the best metallization at 1,100°C, providing result of 96.81%, Femetal of 87.88% and 90.78% of Fetotal. The iron oxides on the DRI were relatively low, namely 2.9%. In this research, prior pellets preparation a magnetic oxidation process on iron ore concentrate was also conducted and changed the magnetite into hematite. The reduction process on its pellets produced 94.15% metallization at 1,100°C, and the DRI contained 97.85% of Fetotal, 85.32% of Femetal and 5.35% of Fe oxides. Furthermore, analyzing a remained carbon of the DRI using microscopy to seek the metal structure formed. The remained carbon was reported around 1-6% C. Next smelting process, it is suggested to have a high residual carbon concentration as there will be a carbon boil mechanism to reduce iron oxides that are still lagging on the DRI.

The availability of energy becomes a major problem in the construction of iron mineral-based smelter to produce ferrous metals in the form of pig iron. Therefore, it is necessary to develop the Krupp-Renn technology that based on coal as a reducing agent to produce pig iron in the form of nuggets. Such a technology employs a rotary kiln that consumes less energy than other furnaces. In this study, reduction process of iron sand concentrates with coal as the reductant was accomplished in a minisized rotary kiln (0.6 m diameter and 6 m length). The process of iron nugget making from iron sand concentrate was conducted in two (2) stages, namely oxidation and reduction processes. The former was accomplished at a temperature above 800°C for 2 (two) hours to produce hematite phase. While the later was carried out at 1250-1300°C for 6-8 hours. Both processes produced iron nuggets that contained more than 90% Fe. The highest Fe content reached 96.49% Fe. Such a nugget could meet the requirement for steel making.Keywords: iron nugget, rotary kiln, Krupp-Renn technology, concentrated iron sand, oxidation and reduction processes. ABSTRAK Ketersediaan energi menjadi masalah utama dalam pendirian smelter berbasis mineral besi untuk menghasilkan produk logam besi dalam bentuk besi wantah, maka teknologi

As an interesting material in large field area, ZnO synthesize has been widely observed. In this research, synthesize was carried out using zinc dross, waste from galvanization process, as starting material by simple heat treatment method. The as-synthesized ZnO obtained were further underwent post-anneal and post-hydrothermal treatment series. From the characterization data, it was found that highest crystallite size was obtained in sample treated with post-hydrothermal treatment at 150oC for 12 hours with value of 1371 nm, which corresponds to its lowest Eg value of 3,086 eV.

This study discusses the characteristics phase of the alumina mixture, namely the γ, α-alumina as well as its ability to adsorb the nickel (II) and magnesium (II) from nickel sulfate due to solvent differences. The γ, α-alumina was synthesized under acidic conditions (pH = 5) from poly aluminum chloride that was calcined at 800 °C by the sol-gel method. The particle size of γ, α-alumina is 15.65 μm; BET specific surface area of 104.12 m2 g−1; mesopores volume of 0.284 mL g−1; and a shape type of IV isotherm curve. Such the characteristic belongs to an adsorbent. The solution of nickel sulfate as Solution (b) has a bigger total adsorption capacity than that of the Solution (a), namely 16.46 mg L−1 and 2.49 mg L−1 respectively. The alkaline buffer formation as the ammonium hydroxide and ammonium chloride in Solution (a) may result in reducing the adsorption capability of the γ,α-alumina. The magnesium concentration of nickel sulfate in Solution (a) is smaller than that of the nickel one, namely 118.36 mg L−1 for the Mg and 486.64 mg L−1 for the Ni. However, the Mg is still more adsorbed around 29.96 mg L−1 compared to the Ni (19.80 mg L−1).