Manufacture and extraction of sulphur

2 Manufacture and extraction of sulphur There are three significant sources of sulphur  

Sulphur dioxide obtained by the extraction of metal sulphide ores 

Sulphur, usually recovered from hydrogen sulphide, from the oil and gas industries. 

1 The Frasch process. This process has been used for almost a hundred years to obtain sulphur from underground deposits. A hole is bored to the bottom of the sulphur-bearing layer using oil-drilling equipment. Three concentric tubes are then placed in the hole. Water at about 160 °C is passed down the outer tube to melt the sulphur which at this stage is heavy and cannot be forced above ground by the water. Therefore compressed air is forced down the central tube to aerate the sulphur sufficiently for it to pass up the third concentric tube to the surface. The molten sulphur is then passed into a separator to allow air to be removed. It is then solidified or stored in the liquid form in steam-heated tanks. 

2 Sulphide ores. Some sulphide ores are roasted in air to convert them 

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