CompuServe Messages

John- The values Jim cited are volumetric basis. A 10x10x8 ft room contains 800 cubic feet. You would have to have 0.4 ft^3 or ~11.5 liters of 100% H2S to reach a 500 ppm concentration. This is extremely unlikely in most circumstances at home, but is entirely possible in some mines lacking ventilation. A far greater risk to rockhounds is entering areas of low oxygen concentration. Hypoxic conditions can occur anywhere insufficient air circulation combines with oxygen hungry materials such as sulfide or telluride ore bodies or high concentrations of organic material. Several years ago, three crew members of a Tuna fishing boat died from both H2S exposure and hypoxia when they lost refrigeration of the fish hold and the tuna began to rot. They attempted to remove the decomposing tuna and died when they entered the confined space. Death was immediate. Oil and natural gas Refining necessarily produce H2S in desulphering crude oil or gas. H2S naturally occurs in oil and gas fields. Many natural gas plants desulfur the natural gas using Claus process sulfur recovery. If you ever fly over Alberta, north of Calgary are huge, and I mean huge!, blocks of sulfur recovered from natural gas. Most refineries produce H2S as a byproduct from crude distallation, catalytic cracking units, hydrotreating and decoking (among others). This H2S is usually converted to elemental sulfur using Sulfur Recovery units. We also operate a Sulfur Recovery Unit and produce about 20 Tons/day of molten sulfur. Someday, I intend to play around with controlled cooling of molten sulfur to try to produce large sulfur crystals. However, sulfur is *really* peculiar. Unlike most liquids, molten sulfur viscosity increases with temperature to become a tarry substance, further heating then results in a drop in viscosity. This is due to the bonding nature of sulfur. It exists as various species, S2, S3, S4, S6, S8 and polyermic S. Forming sulfur crystals is very dependent on initial temperature and rate of cooling. No nearly as simple as making "rock" candy. Michael