Sulfur-Containing Rocks

Elemental sulfur is won from sulfur-containing rocks via the Frasch process. Superheated water, at 160°C and 16 atm, is forced down into an underground bed of sulfur-containing rock. The sulfur melts. The liquid sulfur is forced up to the surface by the use of compressed air. 

Sulfur Sulfur is the sixteenth most abimdant element in Earth s crust, accoimt-ing for 0.0384% by mass. Sulfur occurs as elemental sulfur, as mineral sulfides and sulfates, as H2S(g) in natural gas, and as organosulfur compounds in oil and coal. Extensive deposits of elemental sulfur are found in Texas and Louisiana, some of them in offshore sites. This sulfur is mined using the Frasch process, which is illustrated in Figure 22-9. Superheated water (at about 160 °C and 16 atm) is forced down the outermost of three concentric pipes into an underground bed of sulfur-containing rock. The sulfur melts and forms a liquid pool. Compressed air (at 20-25 atm) is pumped down the innermost pipe and forces the liquid sulfur-water mixture up the remaining pipe. The evaporation of water from the mixture yields formations of solid sulfur, such as those shown in the margin. 

The conducted researches of complexing processes of noble metals on a sulfur-containing CMSG surface formed the basis for development of sorption-photometric, sorption-luminescent, soi ption-atomic-absoi ption, sorption-atomic-emission and sorption-nuclear-physic techniques of the analysis of noble metals in rocks, technological objects and environmental objects. Techniques of separation and detenuination of noble metals in various oxidation levels have been proposed in some cases. 

Another chemist who just missed discovering bromine was J. R. Joss, who in 1824, and again in January, 1826, had recorded in his laboratory notes the appearance of a red color in some hydrochloric acid prepared from gray Hungarian rock salt and Bohemian fuming sulfuric acid. At the time, he attributed this color to the possible presence of selenium from the sulfuric acid. After Balard s discovery, however, he made further experiments with the same materials and became convinced that the red color must be due to bromine. His attempts to obtain more of the bromine-containing rock salt were unsuccessful (147). 

Some methane is manufactured hv the distillation of coal. Coal is a combustible nick formed from the remains of decayed vegetation. Ii is ihe only rock containing significant amounls of carbon. The elemental composition of coal varies between 60% and 95% carbon. Coal also contains hydrogen and oxygen, with small concentrations of nitrogen, chlorine, sulfur, and several metals. Coals are classified by the amount of volatile material they contain, that is. by how much of Ihe mass is vaporized when the coal is healed to about 900 C in the absence of air. Coal that contains more than 15% volatile material is called bituminous coal. Substances released from bituminous coal when it is distilled, in addition to methane, include water, carbon dioxide, ammonia, benzene, toluene, naphthalene, and anthracene In addition, the distillation also yields oils, tars, and sulfur-containing products. The non-volatile component of coal, which remains after distillation, is coke. Coke is almost pure carbon and is an excellent fuel, However, it may contain metals, such as arsenic and lead, which can he serious pollutants if ihe combustion products are released into the atmosphere. 

The use of sulfuric acid in automobile batteries, however, does not account for its production in such vast quantities. The largest single use for sulfuric acid is fertilizers, especially a sulfuric-acid/phosphate-containing-rock mixture called superphosphate. Because phosphorus is a major mineral nutrient needed by plants and because phosphorus is a major component of bones, bone meal was once a commonly used fertilizer. Today, however, phosphate rock, treated with sulfuric acid to become more soluble, can be used, too. 

Tribasic calcium phosphate occurs naturally as the minerals hydroxylapatite, voelicherite, and whitlockite. Commercially, it is prepared by treating phosphate-containing rock with sulfuric acid. Tribasic calcium phosphate powder is then precipitated by the addition of calcium hydroxide. Tribasic calcium phosphate is alternatively prepared by treating calcium hydroxide from limestone with purified phosphoric acid. It may also be obtained from calcined animal bones.Some tribasic calcium phosphate products may be prepared in coarser, directly compressible forms by granulating the powder using roller compaction or spray drying. 

DEEP SEA VENTS are amazing places. Superheated water (up to 400 °C) is released from cracks in the bottom of the ocean. Rocks dissolve and reform. The locally high mineral content and sulfur-containing substances in the water provide an environment that favors unusual organisms that are found nowhere else in the world. 

Typical examples of analytical applications of conventional MECA include the determination of saccharin (sulfur-containing sweetener) in soft drinks, total sulfur and sulfate in detergents, phosphate in detergents and rocks, sulfur dioxide in air, inorganic sulfate in urine, and halides in pesticides. 

NSP is produced by the reaction of phosphate rock and sulfuric acid. This reaction quickly yields a soHd mass containing monocalcium phosphate monohydrate and gypsum, CaSO 2H20, according to the simplified equation... 

Liquid Dispersion Spray columns are used with slurries or when the reaction product is a solid. The absorption of SO9 by a hme slurry is an example. In the treatment of phosphate rock with sulfuric acid, offgases contain HF and SiF4. In a spray column with water, solid particles of fluorosilic acid are formed but do not harm the spray operation. The coefficient /cl in spray columns is about the same as in packed columns, but the spray interfacial area is much lower. Considerable backmixing of the gas also takes place, which helps to make the spray volumetri-caUy inefficient. Deentrainment at the outlet usually is needed. 

Fluorides and dust are emitted to the air from the fertilizer plant. All aspects of phosphate rock processing and finished product handling generate dust, from grinders and pulverizers, pneumatic conveyors, and screens. The mixer/reactors and dens produce fumes that contain silicon tetrafluoride and hydrogen fluoride. A sulfuric acid plant has two principal air emissions sulfur dioxide and acid mist. If pyrite ore is roasted, there will also be particulates in air emissions that may contain heavy metals such as cadmium, mercury, and lead. 

Phosphoric acid is the parent of the phosphates, which contain the tetrahedral P04 anion and are of great commercial importance. Phosphate rock is mined in huge quantities in Florida and Morocco. After being crushed, it is treated with sulfuric acid to give a mixture of sulfates and phosphates called superphosphate, a major fertilizer ... 

The element phosphorus, like nitrogen, is essential to plant and animal life. Although phosphorus was not identified and isolated until 1669, phosphorus-containing materials have been used as fertilizers since ancient times, usually from bird droppings, fish, and bone. The first phosphoric acid was made by treating bone ashes with sulfuric acid. This marked the beginning of the commercial fertilizer industry. Eventually, mined phosphate rock, a poor fertilizer by itself, was substituted for bones as a raw material for phosphoric acid in the mid-1880s. 

The hydrazine hydrochloride can bind the free oxygen present in the plugging solution. It also reduces the amount of sulfur oxides in the cement rock formed after hardening, thus preventing corrosion. The plugging rock has an increased corrosion stability in hydrogen sulfide-containing media. The... 

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