Brunton's Automatic Sampler (Fig. 1), which is one of the best in use, is designed upon a slightly different principle from the others, in that the entire ore-stream is deflected to right or lett. This is accomplished by placing a with a large opening at a certain point in the spout. Just below the bottom of the funnel is a diaphragm or switch, the bottom of which is pivoted midway in the spout. The ore falling against this is diverted to one side or the other according as the dia phragm is turned, Outside of the spout the dia phragm is connected with a suitable gear, whereby it can be deflected at any desired interval, say five seconds in twenty-five, or five seconds in fifty, during which time all the ore passing through the spout is discharged into the sample bin. The first sample is then crushed and elevated, and again reduced by dropping through another spout equipped with a sampler of the same design. The two machines are driven at different speeds to prevent any possible error that might result from isochronal motion. Experience has shown that 10 per cent, of 20 per cent., or 2 per cent. of the original amount of ore, is usually quite sufficient for the final sample. though in exceptional cases 15 per cent. of :10 per cent.. or 41 per cent. of the whole, are taken. Careful tests of this machine in resarnpling lots of ore have shown a limit of error of less than one-fourth of 1 per cent. For further details see Trans. Am. Inst.
Engrs., vol. xiii. p. 689.
Another device to facilitate sampling is the split shovel, which is an ordinary shovel so divided that in being pushed through a lot of finely crushed ore, a certain proportion only, say one-fourth. is taken. Brunton's shovel, Fig. 2, is one of the best of these. This tool. which is described in the Engineering and Xining v.d. li. 715. consists essentially of a flat-bottomed, well-balanced steel shovel, 10 in. in width, having vertical sides, and two central partitions. 21 in. apart. thus dividing the shovel into three compartments, the center one being closed by a curved back, and having a width one-quarter of the whole. The oper ator pushes the shovel into a. pile of finely crushed ore. As he raises the shovel, it is drawn back with a sharp rotary motion to the right, which throws the ore contained in the outside compartments out from the back end of the shovel into a rejected ore pile. When the nec essary throw to accomplish this result has been given, the motion is reversed. and the shovel brought rapidly to the left, which action discharges the sample from the central compart ment of the shovel upon another pile.
While the required motions are somewhat difficult, and beginners are awkward at first, few weeks' practice brings the necessary skill to enable the operator to sample a pile of ore almost as rapidly as it can be shoveled over. Tests at sampling works and different smelters upon hundreds of lots of ore, many of them in duplicate and triplicate, show that there is no difTer•ence between the results obtained by this method and by Cornish quartering in the com mon manner. Experienced operators attain great rapidity in this method of quartering ; in some recent speed tests it was found that a ton of ore could be cut down to a 100-lb. grinder sample by a man in 15 minutes.
In dry-crushing silver mills, where it is desired to take regular and continuous samples, a mechanical arrangement can be fitted to a trough or chute through which the finely crushed ore is passing, which will take a small portion of the pulp at regu lar intervals. AlcDermott's and
Collones automatic samplers are machines devised for this purpose.
ilellermott's Automatic Sam pler, Fig. 3, consists of a spout, C, which, by means of the worm wheel, /), and the pin. G, coming in contact with the lever, A, is moved into the stream of ore pulp, causing a small portion of the current to be directed for an instant into the sample box, II ; the pin, G, having then passed the lever, it returns to original position by spring, F. This arrangement of long-armed lever,. A, with spring return enables the slow revolving wheel, D, not to take samples too fre quently. nor too large: so that the machine can run all day and not take too bulky a sample for convenient handling. The divid ing launder splits up the stream of pulp in a large mill for the same purpose, viz.: to keep sam ple small, by passing sample spout, C. through only a part of the stream. This machine can be adapted to mills in operation, where '• fall " is limited, either by making a few inches drop at some point in the main launder. which carries the pulp or tailings, or, if this is not practicable, by using a long dividing launder, B B, which, being narrow and of metal, will clean itself with less fall than the main wooden launder. The frequency of the samples can he indefinitely increased by adding pins to the D, or increasing the speed of the worm shalt. E. The size of each sample taken can be varied by the widths of the dividing launders and of the sampling spout, CI; these beine' of thin sheet-iron. can be bent by hand to the desired width.
CoUom's Automatic Sampler, Fig. 4. is el,nstrnst.ed upon the same principle as the Mc Dermott. hut the sample spool is fixed to the end of a horizontal arm, which is revolved slowly by means of a bevel gear, cutting a sample of the falling ore each time it passes through it.
Bridgeman's Automatic Sampling Machine is a new device, designed to give practically finished samples. It is a rotary machine, which takes the whole stream of ore for part of the time, and which, in a single passage of the material through it, gives two or more absolutely independent samples. and cuts down each of these a sufficient number of times to give the smallest final samples desirable without re-entshing. The accompanying illustration (Fig. 5) Shows the apparatus in sectional elevation. Extending verti cally from the base is a shaft, A. provided with a bevel-gear wheel, B. Loosely surrou»ding this shaft is an Independent rotary sleeve, C, provided with another bevel wheel, D; and loosely surrounding, the sleeve, C. is another sleeve, B, which in turn has a bevel wheel, E. Means are provided for giving mo tion to the three bevel wheels, 13, 11, and P. Fixed to the sleeve. E. is it rotary device, 0, directly above which is a similar apportioning device, II, fixed to the sleeve, C. Upon the shaft, A, and above the apportioning device, II, is st ill another apportioning device, I. The guide chutes. J, are annular at their tipper portions, and are sepa rated by partitions, K. shallow at one side of the numhine, deepening toward the opposite side, The apportioning devices, 0 and II, are similar in their construction ; they are funnel-shaped throughout the greater part of their area, and terminate at the bottom in an annular spout, L.