World Placer Journal - 2006 - Volume 6, pages 36-41.
Gold recovery in cones in Laos
- the term 'dulanging'.
(1) General Director of Eco-Minex International
The dulang - a remarkable device used by hundreds of thousands of artisanal miners in South-East Asia to recover gold, platinum, tin, diamonds and gems.... ....different from a pan, and not the same as a batea...
The article is a Short Note to clarify the dulang and how it has been confused with a batea, and now devices have been buried in the blanket term of ‘gold pan’. The term ‘panning’ is useful in mainstream English to cover all manner of gold recovery devices directly driven by hand. However the devices are so varied that they deserve and require proper recognition and the new term ‘dulanging’ is proposed to ensure the distinctive nature of operating a dulang is not smothered by the term ‘panning’.
The dulang is distinctive in being a single solid piece of wood that on the outside is a cone tapering to a blunt point and on the inside is a dish-shape.
The dulang is used extensively by artisanal and small-scale miners (ASM) in South-East Asia, notably for recovering gold, platinum, tin (cassiterite) diamonds and gems from placers by manual wet washing.
Two types of dulang are reported in the literature – those with shallow cones and correspondingly shallow dish are used for recovering very dense minerals such as gold and platinum; and dulang with steep cones and deeper dish that are multifunctional being able to recover not only very dense minerals but also lighter valuable minerals such as diamonds.
Although dulang are used by hundreds of thousands of artisanal and small-scale miners (ASM) in South-East Asia, no technical studies of dulang performance seem to have been made.
The conical external shape (regardless of the internal shape) should bestow the dulang additional momentum to maintain its speed of rotation longer, and dampen any tendency to wobble. This advantage probably also applies if the device is rotated clockwise and anticlockwise in rapid succession.
A second advantage of the conical shape is that when the operator tilts the device towards him/her, it will rock to the left and right; not toward and away. This ensures smooth horizontal turning on the ground or supportive water - not possible with a batea or North American gold pan.
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|IT LOOKS LIKE A PAN|
- artisanal miners using dulangs in the Mekong River in northern Laos.
|SURELY IT'S A PAN?|
- the dulang looks like a pan but no!
OR IS IT A BATEA?
- a batea is shaped like a fruit dish or bowl, but the dulong is different...
|NO, IT'S A DULANG...|
...it's a pan, but not as we know it! The dulang is conical on the outside - certainly not a pan shape, certainly not a bowl shape.