GOLD. —Concentration of Tailings.
85
on the small scale, by rockers worked by hand, andon the large scale, by an apparatus called a huddle,or by IIendy’s concentrator. Buddies are of twokinds, convex and concave, both extensively used,but the latter only will be described.
The rocker consists of a simple wooden trough,about 10 feet long, and resting at each end on sup-ports, so that it can be rocked in a manner similarto the cradle already described, the incline beingabout 1 in 12. The concave buddle of Paine and
Stevens is shown in section in Fig. 22. It consistsof a circular wooden table, about 18 feet in diameter,slightly inclined inwards, in the centre of which isan opening about 2-| feet in diameter. From thecentre of this opening rises a vertical shaft, to whicha rotatory motion is communicated by mill gearingabove, and to which several appendages are attached.These are g, a self-raising riffle pulley, to which anupward or downward motion can be given by meansof a rod passing upwards, and connected with an
endless screw at the top, the arms, fj, carrying thebrushes, and the sand distributing troughs, e, e. Thesands having been placed in the box, y, are washedby means of water led from the trough, i, by thepipe, k, into the sieve, z, whence they pass along hto the troughs, e, e. As these rotate they distributethe sands round the circumference of the buddle,where the heaviest particles remain, the light orefinding its way to the centre, the brooms attachedto the arms, ff , maintaining an even surface of sand.When a sufficient quantity of ore has been intro-duced the whole mass on the surface of the buddleis divided into three concentric rings. That in theinterior is thrown away as waste, the middle portionis gradually washed by a stream of water descendingfrom the distributing troughs as shown, and whichcan be led on to the buddle at any distance from thecentral rotating shaft. The sulpliurets, &c., left afterthis operation are added to those at the outer circum-ference, the whole being again passed through thebuddle in order to further enrich it. These head-ings are subjected to a final process of cleansingcalled tossing, when it is intended that the gold shallbe extracted by chlorination. The nature of thisapparatus will be at once understood from theaccompanying sketch, Fig. 23 . It consists of a tubinto which the sulphurets, &c., are introduced, andin which a number of flat iron horizontal stirrers
rotate, the sides of the tub being at the same timestruck rapidly by means of hammers.
The tub is half filled with water, and when thestirrers have been set in motion, making forty-eightrevolutions per minute, the ore is shovelled in nearthe periphery. When nearly full the yoke carrying
the stirrers is raised, and the hammers are set inmotion to induce the rapid settling of the sands. Thewater is now removed, and the sands, having a depth ofabout 13 inches, are divided into three lots. The upper2 inches are thrown away; the next 5 inches areretossed, and the remainder is sent to the chlorina-tion works. When Hendy’s continuous concentrator