ある方のブログを見ていたら https://loneb.net/archives/850 おっ、このリッフルは面白いなあ。樹脂製で似たようなのもあったけど Gold Well Vortex Drop Riffle Sluice Box のリッフルだ。
元々のページはこっちか http://www.goldrushtradingpost.com/gold_well_vortex_sluice
リッフル部分の説明を抜粋すると・・・
The Gold Well Vortex Drop Riffle Sluice works by creating a gentle, vertically oriented vortex. This vortex keeps material in the spiral shaped Wells in motion, causing light material to be flushed out easily and concentrating heavy material. When a piece of gold crosses this vortex, it finds no stable bed to rest on and like a heavy object dropped in a bucket full of ball bearings being vibrated around, it drops to the bottom, where it stays, because there is no force coming up from the bottom to flush it back out.
Horizontal grooves are not designed to trap gold, they are mixing Wells. The slots create turbulence sufficient to cause light material to be forced up into the upper laminar flow regions of the water flow so they will be quickly removed by the water stream flowing through the sluice. The heavier materials move more slowly through the sluice, along the bottom where it is forced to cross the spiral Wells where it is trapped. The horizontal wells will of course trap larger pieces of gold. The Vortex Drop Riffle Sluice thinks it is a concentrator and is truly new and improved technology!
渦状の穴はまあ、想像通りなんだけど、水平溝に軽い粒子を巻き上げさせる役割を持たせているんだなあ。 実は階段型リッフルのスルースボックスの改良案として、リッフル後端部分を少しだけジャンプ台状に持ち上げてみようかと考えていたところだ。もっとも、その後側に砂鉄を溜め込まないような構造も考えないといけないんだけどね。
渦状の穴の方は、中心部分は凸形状にしたらどうなるだろうか？ ゴールドボウルの中心の円錐台状の部分のように軽粒子が水流に乗って排出されれば面白いのだけど・・・そんなにうまくはいかないかな？
