Volcanic sulfur deposits

World sulfur production in 1989 was 40 million tons. " Over 99 percent of the sulfur that is marketed is sold as crude sulfur. The two primary grades are bright, which is bright yellow and at least 99.5 percent (typically 99.9-h %) pure, and dark, which can contain upwards of 0.25 percent carbonaceous material. Recovered sulfur generally is bright, whereas mined sulfur often is dark owing to traces of crude oil, which is associated with salt-dome sulfur deposits. Volcanic sulfur deposits yield bright sulfur, but it often is contaminated with toxic metal oxides. Sulfuric acid production accounts for 93 percent of the elemental sulfur... 

Atomic masses calculated in this manner, using data obtained with a mass spectrometer can in principle be precise to seven or eight significant figures. The accuracy of tabulated atomic masses is limited mostly by variations in natural abundances. Sulfur is an interesting case in point. It consists largely of two isotopes, fiS and fgS. The abundance of sulfur-34 varies from about 4.18% in sulfur deposits in Texas and Louisiana to 4.34% in volcanic sulfur from Italy. This leads to an uncertainty of 0.006 amu in the atomic mass of sulfur. 

Quaternary sulfur deposits are distributed along the present volcanic front. Intersections of transverse faults proposed by Carr et al. (1973) and the present volcanic front coincide with the locations of clusters of the sulfur deposits (Nishiwaki and Yasui, 1974). 

Possibility (1) was proposed by Shikazono (1987b) who considered that the lower values of sulfide sulfur than base-metal vein-type deposits and Kuroko deposits can be explained by the leaching of sulfide sulfur from volcanic rocks with lower values (0%o to -t-5%o) (Uyeda and Sakai, 1984). 

Volcanic and Other Surface Deposits. Sulfur is recovered from volcanic and other surface deposits by a number of different processes, including distillation, flotation, autoclaving, filtration, solvent extraction, or a combination of several of these processes. The Japanese sulfur deposits are reached by tunnel, and mining is done by the room-and-pillar, chamber-and-pillar with filling, and cut-and-fill systems. Sulfur was historically extracted from the ore by a distillation process performed in rows of cast-iron pots, each containing about 180 kg of ore. Each row of pots is connected to a condensation chamber outside the furnace. A short length of pipe connects each pot with a condenser. Brick flues connect combustion gases under the pots. Sulfur vapor flows from the pots to the condensation chamber where the liquid sulfur is collected. The Japanese ore contains 25—35 wt % sulfur. This method has been superseded by other sources of sulfur production. 

Figure 12.7. An Archaeon and Its Environment. Archaea can thrive in habitats as harsh as a volcanic vent. Here, the archaea form an orange mat surrounded by yellow sulfurous deposits. [Krafft-Explorer/Photo Researchers.]...

The principal source of sulfur on Earth is deposits of free sulfur occurring mainly in volcanically active regions. The sulfur was initially formed by the reaction between the two volcanic vapors SO2 and H2S to form H20(/) and Ss(s). What volume of SO2, at 0.961 atm and 22.0°C, was needed to form a sulfur deposit of 4.50 X 10 kg on the slopes of a volcano in Hawaii ... 

Selenium is widely dispersed. It is found, for example, in igneous rocks, volcanic sulfur deposits, hydrothermal deposits, and copper ores. Selenium is used in the electronics industry for the manufacture of rectifiers and photoconductivity cells. Selenium and its compounds are also used as additives in chromium-plating, glass, ceramics, pigment, rubber, photography, lubricants, pharmaceuticals, and organic substances. 

The following reaction was described as the cause of sulfur deposits formed at volcanic sites (see p. 705) ... 

At present, the geochemistry of tellurium is unclear. The average tellurium content of crustal rock is 2 x 10 %. Tellurium is a component of intrusive and extrusive magmas, volcanic gases, and volcanic sulfur deposits, and is usually associated with sulfur and... 

Volcanic-related sulfur deposits are found in several areas of the world. In the East Pacific Basin, volcanic sulfur deposits extend along the Philippines, Japan, the Kuril Islands, and the Kamchatka Peninsula. In the West Pacific or Cordillera Basin, deposits extend alcxig the western side of North and South America through Mexico, Peru, Bolivia, and Chile 169]. 

Large deposits of the yellow burning stone have been found in volcanic regions, such as those of Sicily, and in Texas and Louisiana, USA. Some sulfur deposits are located offshore. The sulfur that the conquistadors cut from the insides of the volcanic crater had been formed when hydrogen sulfide gas from the interior of the earth had reacted with oxidizing gases, sulfur dioxide or air. Historically, volcanic sulfur was the main source of supply. That is not the case today. 

A FIGURE 22.24 Sulfur Deposits Some sulfur deposits can also be found at Earth s surface where volcanic activity has brought the element to the surface. 

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