Due to the fact that the salt and associated
mineral deposits are widely spread and in enormous
quantities, they have become important
resources in both basins for mineral exploitation
and for use as host rock for product storage. For
over four decades, local people have extracted
the salt by using an old fashioned technique,
called here the ‘brine-pumping’ method.
A shallow borehole is drilled into the rock unit
directly above the salt. Brine (saline groundwater)
is pumped through the borehole and left to
evaporate on the ground surface. Relatively pure
halite with slight amounts of associated soluble
minerals is then obtained. This simple and
low-cost method can however cause an environmental
impact in the form of unpredictable
ground subsidence, sinkholes and surface
contamination (Fuenkajorn, 2002). The brine
pumping practice has therefore been limited to
strictly controlled areas, isolated from agricultural
areas and farmlands. Since 1972, a safer and
more productive approach has been taken by
Pimai Salt Co., Ltd. (PSC) which has extracted
the salt by using a solution mining technique.
Solution caverns spaced safely far apart have
been created in the Middle Salt member with
nominal diameters ranging between 45 and 70 m.
A salt roof with a pre-designed thickness is left
intentionally above the caverns which serves as
a supporting beam to prevent excessive ground
movement and subsidence. Currently the annual
production rate of salt from PSC is about 1.5
million tons.
Due to the fact that the salt and associatedmineral deposits are widely spread and in enormousquantities, they have become importantresources in both basins for mineral exploitationand for use as host rock for product storage. Forover four decades, local people have extractedthe salt by using an old fashioned technique,called here the ‘brine-pumping’ method.A shallow borehole is drilled into the rock unitdirectly above the salt. Brine (saline groundwater)is pumped through the borehole and left toevaporate on the ground surface. Relatively purehalite with slight amounts of associated solubleminerals is then obtained. This simple andlow-cost method can however cause an environmentalimpact in the form of unpredictableground subsidence, sinkholes and surfacecontamination (Fuenkajorn, 2002). The brinepumping practice has therefore been limited tostrictly controlled areas, isolated from agriculturalareas and farmlands. Since 1972, a safer andmore productive approach has been taken byPimai Salt Co., Ltd. (PSC) which has extractedthe salt by using a solution mining technique.Solution caverns spaced safely far apart havebeen created in the Middle Salt member withnominal diameters ranging between 45 and 70 m.A salt roof with a pre-designed thickness is leftintentionally above the caverns which serves asa supporting beam to prevent excessive groundmovement and subsidence. Currently the annualproduction rate of salt from PSC is about 1.5million tons.
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