The mining of tin in Thailand dates back to the reign of King Narai during the Ayutthaya period. Tin was used for making spear tips, swords and body armour and so was considered a valuable commodity not only by the Thai Kingdom, but by all Oriental and European powers. During the mid 1800's the demand for tin and related alloys surged. It was used in Bangkok for coins and roof tiles and was sought by industrializing Europe for anti-rust coatings, tin cans, foils and electronics. Thousands of Chinese migrated to Phuket to work in the tin mines where conditions were adverse and labour intensive. History was made at Wat Chalong in 1876, when a riot involving 25 000 migrant workers was quelled by two temple abbots who rallied with the local people.
Over the years the excavation process has evolved and now uses a sophisticated method to mine and extract tin ore. The seabed is scooped up by a bucket ladder, a system of large bucket shaped cups that revolve around a pulley stretching from the top of the dredge down to some 117 meters below sea. The pay-dirt is sent through a large revolving screen, where the oversized particles are discarded and the more precious mixture of sand, gravel and tin is collected. Next it is sieved by one of seven primary jigs before being pumped back up into a hydro-cyclone. Here the heavy, metallic particles are retained and sent through a secondary jig. This gravity theory is also applied to the next two refining stages, the Willoughby jig and the land-chute. Finally the precious remains are dried, bagged and shipped to the Sino-Thai refinery in Phuket. At this stage, the tin material is approximately 30% pure. It is then thoroughly cleaned using plain water to become about 74% pure tin.
Sino-Thai sell all of their tin to the Thailand Smelting Co. Ltd., where it's once again processed and smelted into tin blocks. Tin is used to make common alloys such as bronze, as we see in many Buddha images, solder, used widely in industry, and pewter which is readily available in almost any souvenir shop. Even the aerospace industry depends on an alloy made from titanium and tin for space exploration.
No one could deny the usefulness of tin products in our society, yet the relative value of tin has decreased by about 50% since the hey-days of the industry back in the 1900's. The tin mining business has repeatedly come under fire throughout its long history in Thailand. The environmental impact of early mining was considerable. Open cut tin mines devastated the pristine landscape of Phuket and eventually angered residents. In 1985 construction began of a tantalum refinery, a valuable metal by-product of tin processing. The procedure would have significantly damaged air and water quality, but a citizen protest, 50,000 people strong, broke into chaos resulting in the destruction of the plant.
Nowadays excavation of tin ore is "conducted to reduce the environmental impact as much as possible". The discharge chute is now aimed straight down to the ocean floor which lessens the deluge by up to 90%.Editor's note: This ONLY affects the aquatic life and chokes out all the coral reefs with sedimentation. This sedimentation occurs in a huge area as the the effluent drifts dozens of kilometers with each tidal shift.
Happily we offer visits to a pair of sunken tin dredgers. Ask us about these great local dives
No comments:
Post a Comment