Volatile elements recycling

Fig. 1. Recycling of volatile elements in the Earth. The x-axis is the ratio of the surface (atmosphere, oceans, crust, sediments) inventory divided by the present-day flux at ridges. The y-axis is the amount of volatile elements carried by the oceanic crust and sediments to subduction zones by the volcanic flux at arcs. Neon is not represented because its volcanic flux is not known. Data sources Craig el al. (1975), Matsuo et al. (1978), Le Guern (1982), Staudacher Allegre (1988), Staudigel ct a/. (1989), Allard (1992), Marty (1992,1995), Rea Ruff (1996), Sano Williams (1996), Marty Tolstikhin (1998), Marty Zimmermann (1999), and references therein.

Kramers (2003) calculated major and minor (noble gas) volatile element abundance patterns in the Outer Earth Reservoir (the atmosphere, hydrosphere, oceanic and continental crust, and recycled components in MORB-source mantle). These are presented, normalized to solar abundances, together with data for chondrites in Fig. 5.6. The following observations can be made ... 

It was not nndl the 1950s that detonation flame arresters made of crimped metal ribbon elements were developed and began to be used more freqnendy (Binks 1999). The major impetus for die use of crimped metal ribbon detonation flame arresters in the US was the enactment of clean air legislation (Clean Air Act of 1990) which inadvertently created a safety problem by requiring reductions in volatile organic compound (VOC) emissions. To do this, manifolded vent systems (vapor collection systems) were increasingly installed in many chemical process industry plants which captured VOC vapors and transported them to suitable recovery, recycle, or destruction systems. This emission control requirement has led to the introdnction of ignition risks, for example, from a flare or via spontaneous combustion of an activated carbon adsorber bed. Multiple... 

One of the most notable features of seawater is its high degree of saltiness. In previous chapters, we have discussed various sources of this salt, these being rivers, volcanic gases, and hydrothermal fluids. These elements have ended up in one of four places (1) as dissolved ions in seawater, (2) as sedimentary minerals, (3) as hydrothermal minerals, and (4) as volatiles that reside in the atmosphere. The minerals are recycled via geologic uplift and subduction. Upon return to Earth s surface, these minerals are chemically weathered via acid attack by the atmospheric volatiles remobilizing the salts for return to the ocean in river runoff. 

Because both zinc and magnesium are volatile, these acceptor alloy elements are separated from the actinides by vacuum distillation. The zinc-magnesium overhead product from vacuum distillation is recycled. After the volatile solvent metals are removed, the resultant distillation bottom products (U-Pu for core fuel and U for blanket fuel) are converted to suitable oxides by reaction with oxygen. The oxide products are available for refabrication into new fuel. The FP-3 elements that follow plutonium and the... 

The platinum group metals occur jointly as alloys and as mineral compounds in placer deposits of varying compositions. Ru and Os are separated from the PGM mix by distillation of their volatile oxides, whereas platinum, iridium, palladium, and rhodium are separated by repeated solution and precipitation as complex PGM chlorides, or by solvent extraction and thermal decomposition to sponge or powder. PGM scrap is recycled by melting with collector metals (lead, iron, or copper) followed by element-specific extraction. 

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