GOLD V. BLACK SAND.

Kumara Times, Issue 305, 15 September 1877, Page 2

GOLD V. BLACK SAND.

The Charleston Herald recently pubHshed an article on a new method of separating gold dust from black sand, which we think will be read with interest by our mining friends. From it we take the following:— u In some cases the gold contained in this black sand reaches 'a very high, percentage. But only a small percentage can be saved by the most satisfactory process hitherto employed. Amongst our Californian files by the last mail we came across an article giving a very interesting description of a novel invention, termed the "True Concentrator." This concentrator consists of an endless rubber belt, say four feet wide, and fifty feet long, the width and length being governed possibly only by the rubber manufacturers. This endless belt has a perpendicular rim on each side, about two inches in depth. Thus, when stretched, the surface of the belt forms a broad and shallow sluice. The belt is stretched on large rollers at each end of the frame of the concentrator in such a manner that the surface has a moderate grade. Underneath the machine there is another roller pressing the belt into a large tank filled with water, which forms the receiver. When in operation the rubber belt has a double motion—an oscillating motion and a gradual upward movement, being slowly propelled in the latter case by the rollers on which it is stretched. This double movement answers a twofold purpose. The oscillations keep the pulp in constant motion, while the upward movement carries the fine gold, liberated from the black sand, to the receiver underneath. The pulp is placed in the stationary hopper overhanging the moving belt. Through the bottom of this hopper a small stream of water carries the pulp to the face of a distributor, which in turn carrieait in a semi-liquid state to the inclined rubber belt, at a point within about j eighteen inches of thehead. A perforated trough or pipe at the head of the belting furnishes a steady stream of clean water to play on the material, and the separation of the black sand proceeds. The strong point in the invention consists of th« discovery that the fine gold has an affinity for the rubber, while the black sand h&B little if any. Tin* result is that the black sand passes downward with the water flow in obedience to the law of gravitation, while the tine particles of gold cling to the rubber belting and pass slowly upward, until carried round the upper roller and washed off into the receiver underneath. At first sight it would seem that the trifling corrugations caused by the meshes of

I the canvas forming the base of the belt, ing acted like ripples, preventing the gold from sliding down, but those who are interested in the invention, «nd have experimented most with it, affirm that the smoother the rubber is the more successfully the concentrator performs its work. The tailings work off the concentrator at the foot against the upVard movement of the belt. The experiments made hare been so thoroughly successful that these tailings have not yielded anything higher than traces of gold when subjected to a thorough assay. At a public test given, there was but one opinion expressed concerning the working of the apparatus—and that in its favor. The separation of the fine particles of gold from the worthless but weighty sand was complete." ' -