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Sulphur Production Manual

Revised 10/2005

Chapter 1 - Introduction to Sulphur Production


Definition

Sulphur, also spelled as “sulfur” is a nonmetallic, odorless, tasteless chemical element, insoluble in water, having the Periodic Table atomic symbol of “S”. Sulphur may appear as a gas, liquid, or solid. As a mineral, sulphur appears as a pale yellow, brittle crystalline form, which is known as “native sulphur.” When the element is burned, it produces the familiar smell of sulphur (rotten egg smell). If sulphur is combined with other metallic elements, it forms a “sulfide” such as iron sulfide (fool’s gold). If sulphur is combined with other metallic elements and oxygen, it becomes a “sulfate” such as gypsum (hydrous calcium sulfate).

Sulphur (Sanskrit, sulvere; Latin, sulphurium) was known to the ancients, being referred to as brimstone in the Bible (Genesis). Homer mentioned “pest-averting sulfur” in the 9th century BC. Sometime in the 13th century, the Chinese invented gunpowder, which is a mixture of potassium nitrate, carbon, and sulfur. In the late 1770s, Antoine Lavoisier helped convince the scientific community that sulfur was an element and not a compound.

The United States is the greatest producer of sulphur primarily from buried salt domes where it accumulates in the cap-rock. Hot water is pumped down one pipe to dissolve the sulphur, and returned up another, the Frasch process.

Sulphur is found near hot springs, in volcanic regions, and in salt domes. Sulphur also occurs in natural gas and petroleum crudes and must be removed from these products.

Among its many uses sulphur is a component of black gunpowder, is used in the vulcanization of natural rubber, used as a fungicide and insecticide, and used to make fertilizers. In addition, sulphur is used to produce sulfuric acid for batteries and it is used in fireworks, paper, and some medicines. Sulphur dioxide is a cheap and excellent refrigerant, and was once widely used in home refrigerators before it was replaced by the freons. The only problem was its irritating nature. The freons are nontoxic and noninflammable, but are now forbidden because of the damage that the chlorine does to the ozone layer.

Carbon disulfide, hydrogen sulfide, and sulphur dioxide should be handled carefully. Hydrogen sulfide in small concentrations can be metabolized, but in higher concentrations it quickly can cause death by respiratory paralysis. It quickly deadens the sense of smell. Sulphur dioxide is a dangerous component in atmospheric air pollution.

This manual has been written for the auditor. It is to be used as a training tool and as a reference guide. Any schedules included in the manual are for illustration purposes only and are not to be construed as the accepted format. Audit exams/schedules will need to be tailored to the audit situations encountered and to the auditors’ needs.

Users of this manual are responsible for any changes that occur after the printing or posting of the manual. Before relying on this information, all users should verify the current status of any information by contacting the Comptroller of Public Accounts. Call toll-free: (800) 252-5555. The regular number in Austin is: (512) 463-4600.

To order copies of this manual call (800) 531-5441, ext. 3-3900.


Recovery

Recovery of sulphur is done in three basic ways:

  • Mined through the use of wells drilled to sulphur deposits and worked with the “Frasch” method; (See Diagram)
  • Extracted from the oil or gas stream at a processing plant;
  • Scraped from the surface of the earth or dug out of open pits.

These three recovery methods will be discussed in detail.


Mining

The largest source of sulphur in Texas today is through mining operations. Wells are drilled to the deposits of sulphur 300 to 2000 feet underground. These sulphur deposits are in a solid state and cannot be pumped out. The Frasch method, developed by Herman Frasch of Canada, must be used to recover these deposits. This process consists of circulating superheated hot water and steam through the well melting the sulphur. Then, compressed air is forced into the well, pushing the liquid sulphur up to the surface. This allows the recovery of the sulphur at the surface, where it is metered, cooled, and solidified. The Frasch method is the most widely used method in sulphur production in Texas today. A diagram of a typical mining operation and a close-up of the Frasch method are found at the end of this chapter.


Extraction

The second largest source of sulphur in Texas is through extraction from sour crude oil. Sour crude oil is defined as crude oil containing sulphur. During the early 1900s, sour crude had been considered almost unusable because of its odor and poor burning characteristics. Herman Frasch developed a method for using sour crude to make kerosene. Today, since unleaded gasoline for automobiles is mandated for air pollution reasons, oil refiners have been forced to install sulphur extraction units in order to remove the sulphur from the crude oil in order to produce unleaded gasoline.

Extraction of sulphur from natural gas is another source for sulphur. Sour gas is defined in the Gas Production Tax Statute, Sec. 201.001 (8) as “gas with more than 1-1/2 grains of hydrogen sulfide per 100 cubic feet or more than 30 grains of sulphur per 100 cubic feet.” The natural gas is sent to a processing plant where the hydrogen sulfide (sulphur) is extracted and where sweet (marketable) gas remains. A method called the “Claus Process” is used to convert the sulphur compounds in sour gas to elemental sulphur. This process, invented by English scientist C. F. Claus, is now the most widely used method for extraction of sulphur from sour gas.

When the refiner or processing plant produces sulphur, it may be in a solid state (less than 238 degrees Fahrenheit) or in a molten state (greater than 238 degrees Fahrenheit). The plant may convert molten sulphur to a solid state by storing it and letting it cool to a solid and then load it onto ships, barges, or railroad cars. If the plant does not convert the molten sulphur to a solid, the liquid sulphur is pumped directly to railroad cars, ships, or barges, which are heated and insulated to maintain the sulphur in a molten state.


Scraping/Digging

In Texas scraping and digging of the sulphur from the ground is still continued near the Gulf Coast where deposits of sulphur are found at or near the surface. These deposits of native sulphur are being depleted, and this method is now the smallest source of sulphur in Texas.


Measurement

Sulphur is generally measured in its solidified state in “long tons”.

1 Long Ton = 2,240 lbs.

If sulphur is in a molten state, it must be converted to long tons for tax purposes. See Chapter 2 for details on converting measurements.

[ FRASCH METHOD ]

[ MINING OPERATION ]


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