This equipment is basically a rocker with two sluices distributed in two levels. The first sluice is approximately 2.5-3.5 cm long and 40-50 cm wide. The second sluice is similar and the distance between both sluices is 15-20 cm. The design considers the lower end of the first sluice at an angle of 40-45° and connected with a screen which rejects coarse material and the fine material pass to the second sluice. Some designs consider the first sluice without riffle and others include riffles in both sluices.
During the operation the ore is fed in slurry form. If the material is too big, it must be removed manually and lumps have to be disintegrated. Basically, the equipment is able to concentrate coarse and free gold particles. The material can be fed by using a shovel and adding water, but the operation must be done carefully so that the equipment can’t be overcharged and the gold losses can be minimized. For this reason, to feed homogenous slurry is a good option. Similarly to the rocker, the water flow is a key element in the operation and it is extremely important to maintain a constant flow through the sluices. The second sluice must trap most the gold and sometimes during the process is necessary to clean the riffles in order to remove the heavy material.
The heavy material can be cleaned by using a gold pan in order to improve the concentrate quality or sent o the lab for gold and silver assays. It is important to perform a mass balance so that we can know the metallurgical performance.
There are other equipments similar to the rocket and were used to reduce the water consumption or perform concentration an amalgamation at the same time. Some of these old equipments are the Pudding-Tub and the Siberian Trough. They work under the same principle as the rocker and the operation performance is related to the operator’s skill.
Schematic view of Long Tom