Oxidizing zones

There are over 65 known vanadium-bearing minerals, some of the more important are Hsted in Table 1. Patronite, bravoite, sulvanite, davidite, and roscoehte are classified as primary minerals, whereas all of the others are secondary products which form in the oxidizing zone of the upper Hthosphere. 

Copper ore minerals maybe classified as primary, secondary, oxidized, and native copper. Primaryrninerals were concentrated in ore bodies by hydrothermal processes secondary minerals formed when copper sulfide deposits exposed at the surface were leached by weathering and groundwater, and the copper reprecipitated near the water table (see Metallurgy, extractive). The important copper minerals are Hsted in Table 1. Of the sulfide ores, bornite, chalcopyrite, and tetrahedrite—teimantite are primary minerals and coveUite, chalcocite, and digenite are more commonly secondary minerals. The oxide minerals, such as chrysocoUa, malachite, and azurite, were formed by oxidation of surface sulfides. Native copper is usually found in the oxidized zone. However, the principal native copper deposits in Michigan are considered primary (5). 

For the dilute reactive constituent R which forms the oxide RO , let the thickness of the internal oxidation zone be then for the inward diffusion of oxygen, mole fraction No... 

Williams, P. A. Oxide Zone Geochemistry , Ellis Horwood Chichester, 1990 p. 115. 

Over 2 weeks of root-soil contact, Fe + close to the roots was oxidized by O2 from the roots, and substantial quantities of iron were transferred towards the root plane producing a well-defined zone of Fe(OH)3 accumulation. The pH in the oxidation zone fell. In both the soils studied, the amount of H+ formed in... 

Fig. 1. Distribution of copper deposits in northern Chile including those containing atacamite in the oxide zone. DFZ is the Domeyko Fault Zone and ACL is Antofagasta-Calama Lineament. The land between the High Andes and the coast is the hyper-arid central Atacama Desert.

Cameron, E.M., Leybourne, M.I., Palacios, C. 2007. Atacamite in the oxide zone of copper deposits in northern Chile Involvement of deep formation waters Mineralium Deposita, 42, 205-218. 

Space for estimation Estimation is a mathematical process whereas the main constraint on the orebody is the geological condition. Therefore, it is necessary to introduce the spatial limits of mineralization. For this project mineralization is not only limited by the vein but also it will be limited by the oxidized zone so that, the estimated space is that part of vein, which is located in oxidized atmosphere (Figure 6). 

This project had targeted gold, but the results show there is little hope of obtaining much gold in this area. The thickness of the oxidized zone, the size of... 

Fig. 6. State of Quartz Vein (Red) inside of Oxidized Zone (Yellow).

The thickness of the oxidized zone is not very great in this area, so it is necessary to establish a plant for extracting gold from sulfide zone. 

Drilling should be designed to cross the vein at a depth less than 30 meter because of oxidized zone thickness. 

Natural gas is reacted with steam on an Ni-based catalyst in a primary reformer to produce syngas at a residence time of several seconds, with an H2 CO ratio of 3 according to reaction (9.1). Reformed gas is obtained at about 930 °C and pressures of 15-30 bar. The CH4 conversion is typically 90-92% and the composition of the primary reformer outlet stream approaches that predicted by thermodynamic equilibrium for a CH4 H20 = 1 3 feed. A secondary autothermal reformer is placed just at the exit of the primary reformer in which the unconverted CH4 is reacted with O2 at the top of a refractory lined tube. The mixture is then equilibrated on an Ni catalyst located below the oxidation zone [21]. The main limit of the SR reaction is thermodynamics, which determines very high conversions only at temperatures above 900 °C. The catalyst activity is important but not decisive, with the heat transfer coefficient of the internal tube wall being the rate-limiting parameter [19, 20]. 

The Mina Fe deposit at Salamanca, Spain, presents an interesting potential analogue for waste package interactions with SNF. The oxidized zone has a large abundance of Fe(III) and Mn-Fe oxyhydroxides (Perez del Villar et al. 2002). 

---