Crude Sulphur (Native Sulphur)
One of the most naturally plentifully available 
elements in the world, sulphur has been mined, refined and used by mankind for centuries. Natural sulphur deposits, often referred to as ‘native sulphur’, are most often found in regions of volcanic activity, and because of this sulphur has historically been both revered and vilified as ‘brimstone’ by ancient peoples who believed that the terrible stone with its foul smell was thrown up directly from the underworld.
When in its pure crystalline form, sulphur forms bright yellow crystals which give off a rather unpleasant scent. The unmistakable smell, (not unlike rotting eggs) which emanates from sulphur deposits does not actually come from the sulphur itself, but from the hydrogen sulphide which is created during the hydrogenation of sulphates. Sulphur also gives off sulphur dioxide, a gas which smells strongly like a freshly struck match, and which can cause serious pulmonary illness if inhaled on a regular basis.
Crude sulphur is a highly useful commodity which lends itself to a range of purposes. Crude sulphur can be bright or dark in color, but is always free of selenium, tellurium, and arsenic. It can be used to make insecticides, fungicides, and bleaches, and its refined form is used in the production of vulcanized rubber, acne treatments, cellophane, and gunpowder, amongst other things.
Where In The World Is Sulphur?
Because sulphur is often found near regions with great volcanic activity, it is quite predominant around the so called ‘Pacific Ring of Fire’, a region of high volcanic activity where several tectonics meet, subside and grind under and against one another. This region includes countries such as Japan, New Zealand, Indonesia, and the coast of North and South America. Some of these countries, such as Indonesia, Chile and Japan have active sulphur mining industries, others, such as New Zealand, are content to let their sulphur rich volcanic environments simply act as tourist attractions. Historically, Sicily was the main source of the world’s sulphur, however modern developments have cause the sulphur industry to shift to countries located on the aforementioned ‘Ring of Fire’.
The United States boasts a number of sulphur deposits, many of which have been worked extensively using the Frasch method of extraction which was invented in Louisiana, and is expanded upon later in this article. Other sulphur rich sites in the United States include Alaska, California, Colorado, Idaho, Texas, Utah, and Wyoming.
Extracting Sulphur
Though native sulphur occurs naturally in fairly large quantities, extracting it from the surrounding material is no easy task. There are two main methods of sulphur extraction in common use, however many variants of these methods have been developed over time. The first extraction method to be discussed here is the traditional Sicilian method, which creates a crude sulphur product, the second is a more advanced modern method that results in sulphur with a purity of more than 99%.
The traditional method involves simply burning rocks containing sulphur. A great deal of the sulphur is burned up in this process (it is estimated that up to 30% is turned into gas and lost during the burning process), but the rest of the sulphur in the rocks melts and flows down where it can be collected.
In Sicily, this burning process was carried out in kiln pits known as ‘calceroni’. They were rather large, bring over 50 meters wide, and 30 tall, with solid thick mortar walls encircling them. Ore was packed into these pits, which were built into hillsides, with channels running through the ore known as ‘draught holes’. Fire was inserted into these channels, setting the sulphur ore alight. Once the fire had taken, the draught holes were covered, and the pit was left to burn. The sulphur that wasn’t lost as gas melted and flowed down toward the bottom of the pit, where a tap was placed. The molten sulphur was then drawn off every few hours. In total, the burning could sometimes take as long as two and a half months to complete, though it was more usual for the burning to be completed before the second month.
The more modern method for extracting sulphur is known as the Frasch method, developed by a German American scientist, Herman Frasch who was connected with the Louisiana sulphur industry. Unlike traditional methods, which require the sulphur ore to first be mined and brought to the surface by hoists or human labor, in the Frasch method a drill hole is simply made into underground sulphur deposits, and a series of concentric pipes inserted into the hole. The outer pipes are pumped with blisteringly hot superheated steam which reaches temperatures exceeding 150 degrees Celsius.
The heat from the steam inside the pipe liquefies sulphur, which has a rather low melting temperature of just 115 degrees centigrade. Compressed air is then pumped into the central pipe and bubbles through the molten sulphur, sending it up to the surface, where it solidifies with purity levels in excess of 99%. For obvious reasons, this method has superceeded the Sicilian method in the majority of sulphur mines, though some localities do still use variants of Sicilian extraction techniques to obtain sulphur.
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