US2089780A - Riffle - Google Patents

Description

Aug. 10, 1937. I I w BELL 2,089,780

RIFFLE Filed July 9, 1955 Elma/whom Harry W. Bell Patented Aug. 10, 1937 STATES PATENT FFICE RIFFLE Washington Application July 9, 1935, Serial No. 30,460

2 Claims.

My invention relates to rifiles such as are employed for catching and segregating gold values, particularly fine dust.

Placer mining or dredging operations always take place in relatively remote spots, generally requiring packing in for considerable distances over rough country. Weight is therefore an item of considerable moment. Replacement or repair of equipment is seldom easy to accomplish, and suspension of operations because of break-down of equipment becomes a serious matter, especially where, as in certain parts of Alaska, the working season is a comparatively short portion of the year.

Aside from the first object of all rifiles, namely, to catch the gold, and all of it, it is a primary object of this invention to provide a riille unit which is light in weight, durable, and readily repairable on the spot, and which is therefore admirably suited for use under the conditions outlined above.

It is a further object to make a rifile of material which is largely waste and available in large quantities, and which can therefore be made and sold cheaply, a material fulfilling these requirements being rubber tire casing material, particularly but not essentially the tread portion or" such casing.

It is especially an object to provide a rifile which is efficient and rapid in saving the gold, so that large quantities of gold-bearing gravel and sand may be worked through the riffle, thus making it economically possible to handle larger quantities of material in which the gold-bearing content may be relatively low, for example, even tailings of old workings.

Since fine gold particles worked in a riffle will find their way into seemingly impenetrable crevices it is a further object to provide a rifile which, though it may be made of individual strips with spacer elements between them, may yet be made tight at all joints to prevent secretion of gold in the joints between the rilile elements and the spacers.

It is a still further object to provide a riffle which can be readily handled as a unit, and can be readily lifted and removed from the deposited sand, clay and gold at clean-up times.

It is a further object to provide a rifiie which may readily be formed in various patterns to suit the individual taste or desire of the user.

A further object is to provide a riflle unit so formed that through the action of the water, gravel, sand and the like moving thereover it will automatically iree itself from any gravel which may tend to lodge between the rifile elements, thereby automatically preventing clogging of the riflle units.

My invention comprises the novel riifie unit and the novel riiile element and their relative combination and arrangement, as shown in the accompanying drawing by way of illustration, and as will be made clear in this specification and more particularly defined by the claims terminating the same.

Figure l is a perspective View, with parts broken away, showing two such rifile units in a sluice box.

Figure 2 is in part an elevation and in part a section through such a rifiie unit.

Figure 3 is a section taken transversely across a riffie unit of somewhat modified form.

The sluice box in itself forms no part of my present invention, and that shown is merely a typical sluice box by way of illustrating the manner in which my rifile unit may be incorporated in such a sluice box. It comprises the bottom 4, sides 40 and 4|, supporting and bracing elements 42, and hold-down elements 43 secured inside the sides 49 and 4| to hold the rifile units in place resting upon the bottom l.

In a typical form, illustrated in the drawing, the rifile unit comprises a plurality of strips I cut from rubber tire casing material. Old solid rubber truck tires may also be cut into strips and used for this purpose. Rods 2 pass through a number of such strips, spacer elements 3 holding the latter spaced apart, and nuts 20, threaded on the rods, hold the spacers and strips together so that the whole, in the form illustrated, comprises a grid in which the strips I are held on edge in parallel spaced-apart face-to-face relationship, and with the strips extending transversely to the direction of water flow, indicated by the arrows F. Preferably the strips are so arranged that while generally upright they are somewhat inclined to the direction of water flow, and I consider it preferable to leave the tread surface, when the strips are made of tread material, as is preferable, on the upstream side of the water flow, so that the natural transverse concavity of the material tends to curve its upper edge downstream. This is shown in Figure 2.

An advantage of this is that there is presented first to rocks or gravel, as indicated at R, the comparatively thick, tough rubber of the tread, as the gravel rolls downstream, and in addition there is formed a sharp edge on the downstream side, stifiened and reinforced by the embedded fabric Ill, over which the water riflies and eddies,

thus breaking up its direct flow and effecting rapid deposition of the gold, as indicated at G. It has been found that rifiies formed of metal, in addition to weighing excessively, wear away comparatively rapidly under the abrasive eifect of the sand and gravel, but the rubber, while sufiiciently stiff to form the eddy currents, does not wear away, and by its inherent elasticity and flexibility yields somewhat to the pounding of the gravel, and is continually flexing, and it is a proven fact that it does not wear away appre: ciably during a season.

To further the flexibility of the strips l, the rods 2 are spaced apart in the direction of the length of the strips I, so that there is left a sub.- stantial portion of each strip which is unsupported, and therefore flexible. This flexibility serves a further purpose in that a piece of gravel tending to lodge or wedge itself between any two adjacent strips will, by the flexing action of these strips, be squeezed and worked free, so that the riiiie is selfcleaning and nonclogging.

Preferably the spacer elements 3 are formed of short lengths of rubber tubing, for example, comparatively stiif garden hose. Thus they are compressible and their ends can be pressed tightly against the adjacent strips i, which in themselves, of course, are somewhat compressible, by tightening up the nuts 21%, thereby completely closing any joint between the spacers and the strips to prevent the entrance and secretion of gold in such crevices. Gold, when passed over rifiies, has the peculiar property of working into minute cracks and fissures, for example, into nail holes, and a considerable quantity of gold might otherwise work into the holes through which the rods extend, or into the interior of the spacer elements 3, if the latter were not tightly pressed against the faces of the strips.

To make the unit easy to handle I prefer to employ frame elements such as the angle irons 5 at each end of a unit. The unit thus formed may be made of a size which is convenient for packing, and which is light in weight as compared to any riiile with which I am familiar, except one made of wood, and wooden riiiles have the very serious disadvantage that they wear out rapidly. Such a unit as this, composed of strips which have paraliei smooth faces, provides no anchoring means which will resist pulling the unit from the sand, clay and the like, indicated at S in Figure 2, which lodges between the riiile units. At cleanup time the riiile must be lifted from this mass of material to enable the collected material to be washed down the sluice box to affordaccess to the gold, and it has been found in practice that such riiile as this is not difficult to lift out, even though the collected material may be of a claylike nature, which in some instances becomes practically a cement, greatly resisting eflorts to remove the riiiie.

As mentioned above, it is preferable that the tread surface of the strips be placed on the upstream side. These tread surfaces, though made of worn tires, will ordinarily have left on them certain irregularities of the tread pattern (see Figure 3) and these irregularities serve further to break up and riflie the water flowing over the unit.

While the strips have been shown extending transversely of the sluice box, this is only one way in which my invention may be manufactured, and indeed the pattern may be any which suits the convenience of the manufacturer or the desire of the user. Furthermore, instead of straight upper edges, the upper edge of each strip may be scalloped, as shown at H in Figure 3, or otherwise edge, upstanding from the bottom 4 of the sluice box, since the fabric plies l6 effectively resist wear and serve to stiifen the riiiles, but the strips might be otherwise placed without departing from the spirit of my invention as defined in the claims.

the action of the water, sand, gravel and gold, and this. vibration will tend to segregate the material and to effect additional riiiiing of the water in addition to the property previously mentioned of freeing rocks which might tend to lodge between the strips, and this vibration, therefore, which cannot be present in a riiile made of any nonyielding material, presents a further advantage in this riflie.

What I claim as my invention is:

The strips i, being flexible, will vibrate under 1. A riflie unit for disposition in a sluice box,

comprising a plurality of flexible strips of rubber material, each having a scalloped edge, and supporting said strips disposed on edge in spacedapart, parallel, face to face relation, with their scalloped edges uppermost, and with the scallops on adjacent strips arranged in relatively staggered relationship.

2. A rifiie unit for disposition within a sluice box, comprising a plurality of readily flexible strips disposed on edge in face to face relation,

rods extending through apertures in the strips from end to end of the unit, and spaced apart lengthwise of the strips, spacing tubes having a bore considerably larger than the rods, surround ing the rods, and of such an outside diameter and interposed between adjacent strips in such relationship thereto as to engage the strips from substantially their lower edges to above their centers, to stiffen the major part of each strip,

while leaving the strips upper edges free to flex by the flow of material over the strips, and means to press the spacing elements into contiguous gripping engagement with the strips.

1 HARRY W. BELL.

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