China
Africa
Explore chapters and articles related to this topic
Metal–Crucible Interactions
Published in Nagaiyar Krishnamurthy, Metal–Crucible Interactions, 2023
That the eras of civilization are named after metals highlights the exceptional influence of metals on human life from the start. Interestingly, the knowledge that there are metals and that they are useful was revealed to our ancestors by nature presenting some of the most important and useful metals in native forms. A metal in the un-combined or elemental state in nature is considered to be occurring in the native form. Native gold was relatively common and occurred as small flakes separated from the original deposits by weathering and transportation. Native silver and copper were less common. Copper in the native form was invariably found in small amounts but in more widely distributed locations (Bunch and Hellemans 2004). Native iron was found in locations where meteorites had deposited it on the surface of the earth in large masses of iron or as an alloy of iron and nickel. No occurrence of native iron could be linked to processes in the earth's crust.
Metals
Published in Jill L. Baker, Technology of the Ancient Near East, 2018
On the other hand, iron was labor intensive and difficult to work with (Muhly 2003:180). Smelting iron was achieved by a bloomer process, named for the type of furnace used for smelting iron from its oxides. The iron-smelting furnace produced a bloom, a spongy mass of iron and slag. The slag was called sponge iron, which was hammered to consolidate the mass into wrought iron. The hammering was done when the mass was quite hot to squeeze out the slag and consolidate the iron particles (Muhly 2003:180). Small quantities of phosphorus in iron ore had the same effect as carbon in iron but could cause brittleness. Nevertheless, phosphorous iron was selected because it remained sharp. Iron could be found in Egypt and the Sinai Peninsula at sites such as Wadi el-Dabba in the Eastern Desert, the Bahariya Oasis in the Western Desert, Naukratis, and Tell Defena (Odgen 2009:166). Iron was obtained from native iron; telluric iron, whose use was minimal; iron ore; and chance findings of meteoric iron. Some early examples of iron use in Egypt date to Predynastic periods, with more frequent use occurring in the late second millennium bce (Ogden 2009:166–167).
Meeting Stringent Metals Removal Requirements With Iron Adsorption/Coprecipitation
Published in Bell John W., Proceedings of the 44th Industrial Waste Conference May 9, 10, 11, 1989, 1990
Mark A. Manzione, Douglas T. Merrill, Mary McLearn, Winston Chow
Greater metals adsorption and better solids separations are obtained as the amount of iron present increases (iron present = sum of native iron and reagent iron). However, more iron means more sludge to process and dispose of, and when the iron present exceeds 300 to 400 mg/L, sedimentation may become thickening-limited and the sludge blanket difficult to control. The minimum iron dose required for good solids separation is about 10 mg/L.
Triassic to Neogene tectono-magmatic events within Lorne Basin evolution, coastal New South Wales, eastern Australia
Published in Australian Journal of Earth Sciences, 2020
F. L. Sutherland, I. T. Graham, H. Zwingmann, D. J. Och, C. J. Gardner, R. E. Pogson, R. J. Griffiths, A. Lay
Some features of the Lorne Basin led Tonkin (1998) to suggest a meteoritic impact origin. He cited its near-circular basin shape, the infill of coarse basal clastic beds, the faulted basin structure, accompanying magmatic intrusion and recovery of native iron in glassy dykes in the basement rocks. He proposed that a meteorite several kilometres across was involved. Other tectonic and magmatic/volcanic cratering events are also suggested for the basin formation (Li et al., 2012; Richardson et al., 2014), leaving its origin open for further consideration.
Sustainable long-alkanes biodegradation with moderate pre-oxidation in soil
Published in Soil and Sediment Contamination: An International Journal, 2023
Jinlan Xu, Zhengli Yang, Muhammad A. Imran, Xiumin Li, Shengyang Luo
The instantaneous intensity of •OH with respect to reaction time was presented in Figure 1a. The highest instantaneous •OH intensity with moderate pre-oxidation was measured as 3.60 × 10−2 a.u. in soil S1 and 4.01 × 10−2 a.u in soil S2, which were 2.42 × 10−2 a.u. and 2.52 × 10−2 a.u. lower than excessive pre-oxidation (6.02 × 10−2 a.u. and 6.53 × 10−2 a.u.), respectively (shown in Table 1). The instantaneous •OH intensities showed a slight difference for soils S1 and S2, which can be attributed to native iron contents and soil properties (An et al., 2011; Fanaei, Moussavi, and Shekoohiyan 2020). The second dose of H2O2 showed a relatively lower •OH intensity as less Fe2+ available to activate H2O2 compared to the first dose. As shown in Figure 1b, destruction of hydrocarbon degraders (D) decreased, and residual hydrocarbon degraders activity increased with moderate pre-oxidation due to low •OH intensity. The D was only 14–17% with moderate pre-oxidation according to Eq.1. However, excessive pre-oxidation showed 65% and 47% D in soil S1 and S2, respectively (Figure 1b). As discussed above, bacteria count and activity decreased with increased oxidant concentration. In comparison with the selected literature, the D was much lower than 32% in our previous study (Xu et al. 2016), 24% in Gong (2012), and 33% in Bajagain, Lee, and Jeong (2018a). Likewise, the residual activity of hydrocarbon degraders with moderate pre-oxidation was 0.026 (67%) and 0.018 (42%) mol CO2/kg, more than excessive pre-oxidation (Table 1). A study by Gong (2012) reported that the activity of hydrocarbon degraders was high under the condition of low H2O2 concentration. These results demonstrated that both the quantity and activity of hydrocarbon degraders were protected by controlling •OH intensity, which was important for the TPH removal during the subsequent biodegradation.