ABSTRACT
Mining has been carried out since ancient times to extract valuable minerals and other geological materials from the earth. In the pre-1990s, tin mining was a major industry in Malaysia, which was then the largest producer in the world. However, the combination of dwindling deposits, escalating costs, and low prices caused the industry to collapse. In 2007, China and Indonesia became the largest producers, each contributing approximately 43% to the global market. About one-third of all the tin mined in the world today comes from the Indonesian islands of Bangka and Belitung. Tin dredges are best used where there are large expanses of alluvial soils without excessive rock formations and also offshore. Tin dredges are large machines and can weigh more than 4500 tonnes, with a oating support-a pontoon in excess of 75 meters in length and 35 meters in width. The largest dredges can be equipped with up to 150 digging buckets, each weighing more than 3.5 tonnes and digging up to 45 meters in depth. Tin dredging has evolved over a few decades and in its present form, unchanged since the late 1980s, was one of the most efcient methods of mining. Malaysia at that time together with inter national consultants such as W.F. Payne & Sons, was at the forefront of dredge design and manufacture. Most of the other items were locally cast or fabricated except for a few specialized items such as large motors and gearboxes. Similar to the rest of the world in those days, calculations were made with slide rules, computers had not been invented yet, and design standards were still quite rudimentary. Many components were large in size and were often over-designed and made to less than exact specications. When eld problems or failures were encountered, engineers had to solve them fast to reduce loss of production. They were required to have hands-on experience and the ability to plan and execute repairs quickly and efciently, and often to local sources that made spares of adequate quality . Recurring problems such as those described in Case Studies 2 and 3 were outsourced to the appropriate specialists for investigation.
