Sulfur solidification

Keywords Sulfur and arsenic-bearing gold ore Double-layered pellet roasting Removal of arsenic and sulfur Solidification of arsenic and sulfur... 

Increased sulfur recovery can be obtained with a modification of the Clinsulf process that uses two parallel Clinsulf reactors downstream of the second condenser. The first of the two parallel reactors is operated at a temperature below the sulfur solidification point by cooling the reactor internally to less than 100°C at the outlet, while the second reactor is regenerating. The two parallel reactors alternate between reaction/adsorption and regeneration modes of operation. Linde has investigated sub-solid-point operation at its test facility in Hdllriegel-skreuth and claims that sulfur recoveries up to 99.8% can be achieved (Linde, 1988). In 1994, it was reported that two Clinsulf plants were in operation (Linde A.G., 1994). 

Nickel—Iron and Cobalt—Iron Alloys. Selenium improves the machinabifity of Ni—Ee and Co—Ee alloys which are used for electrical appfications. Neither sulfur nor tellurium are usefiil additives because these elements cause hot britdeness. The addition of 0.4—0.5% selenium promotes a columnar crystal stmcture on solidification, doubling the coercive force of cobalt—iron-titanium alloy permanent magnets produced with an equiaxial grain stmcture. 

Upon solidification of molten sulfur, Stt rapidly changes into S]l, which is converted into SL, although at a much slower rate. The molecular stmcture of Stt is that of an octatomic sulfur chain (1,2). The symbol S]1 designates long, polymerized chains of elemental sulfur. SX is perhaps the most characteristic molecular form of sulfur, namely, that of a crown-shaped, octatomic sulfur ring designated in more recent Hterature as (3). The allotropes have different solubiUty in carbon disulfide. Stt and SX are soluble in carbon disulfide, whereas S]1 does not dissolve in this solvent. 

The hydrolysis of the reaction mixture and subsequent separation of the acid is the procedure given by Gilman and Parker (Org. Syn. 5, 25). Sulfuric acid should be added during the hydrolysis as long as any particles of magnesium are present. The water layer does not become clear, due to solidification of the organic acid. 

However, since the latter reaction is an equilibrium process the Claus sulfur still contains traces of H2S (200-350 ppm, mostly in the form of polysulfanes) which causes serious problems since the H2S partly escapes on cooling or solidification of the sulfur. Obviously, the H2S content needs to be controlled because of the extreme toxicity of hydrogen sulfide and its ability... 

In conventional aluminum-deoxidized steels, the extra-low dissolved oxygen content maintains the sulfur in solution in the liquid stoel until the end of the solidification process. Since sulfur exhibits virtually no solubility in the solid steel — less than 0,001% in the bcc structure — a > iS-Fe eutectic suddenly precipitates at the as cast grain boundaries, the so called "Type II" structure described by Sims ( ). This weakens the as cast structure and also results in elongated MnS inclusions in the hot rolled steel plates, coils, sheets, bars, wires etc, as shown in Figure 5,... 

Solidification point (53°), 3-Macter insol in ether-alcohol, 4-Ash, 5-Reaction with sulfuric acid, 6-rPrimary amines, 7-Moisture, 8-Reaction (Alkalinity), 9-Granulation. Following solubility values for DPA are given in lOOg of solvent water Q.03g at 25° methanol 57.5g at 19.5° ethanol 56.Og at 19-5° acetone 298.6g at 28° chloroform 206.3g at 28° and toluene 227.7g... 

An ordinary glass funnel suspended in the neck serves less satisfactorily, whereas with a water condenser solidification of the sulfur trioxide causes difficulty. 

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