Year: 1899

page_text: Date of Application, 4th Sept., 1899-Accepted, 4th Nov., 1899
We, IRA AUSTIN CAMMETT and FRANK EDWARD SHEPARD, both of The Denver
Engineering Works Company, Denver, in the State of Colorado, in the United
States of America, Engineers, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
-
$6
One object of our invention is to improve the riffled surface of the tables of ore
concentrators, of that class in which the table is given an end-shake" movement.
This end-shape movement or reciprocation assists in the separation of the values
from the sand and tailings, and at the same time produces a progressive move-
ment of the values along the table surface in the line of the movement. It is
customary in some forms of such tables to provide riffles extending either in the
line of the movement or at a slight angle thereto, and to so incline the surface of
the table that the water flows across from riffle to riffle transversely, carrying with
it the sand and dust of the pulp and leaving the values in the channels between
the riffles. The values by the propelling effect of the end-shake movement, are
carried along between the riffles until they fall from the foot of the table into
a suitable receptacle. The riffles may taper off and terminate in an oblique
line and the unriffled area may be roughened by applying paint mixed with sand.
While such a roughening tends to prevent, to a large extent, the loss of values
along with the wash water and tailings, such roughened surface does not, in any
sense, guide the values toward the foot end of the table. All the advantages of
an unriffled portion toward the foot of the table may be retained, and all the
disadvantages be gotten rid of, by continuing the riffles at a diminished height
across such area to the foot of the table. The reduced portion of such riffles should
be so low as not to interfere with the transverse flow of the wash water and light
slime toward the tailings side of the table, yet their presence is sufficient to
exert a very decided guiding tendency to the heavier particles which constitute
the values, and which are prevented by the low riffles from being carried trans-
versely. They, therefore, travel slowly in line with the riffles towards the foot
of the table.
Another object of our invention is to so mount the table that true rectilinear
reciprocation without any vertical movement or jar will be effected.
Fig. 1 is a diagrammatic plan view of the table.
D
Fig. 2 is a longitudinal section on the section plane 2-2 of Fig. 1; and
Figs. 3 to 10 are a series of transverse sections on the respective planes B. C
D. . F. G, H. and J. of Fig. 1.
Certain features (as will be apparent to anyone skilled in the art), are exag
gerated for the purpose of clear illustration in the drawings.
The head end of the table surface is provided with a gentle upward incline b,

page_text: instead of a vertical confining wall at that point. This incline, while it confines
the pulp and water, does not produce a wave along the surface, such as would be
produced at each movement of the table if it were an abrupt vertical wall.
Preferably, also, the riffles c, d, e, f, g, h, i, also rise at the same point, as shown
in the drawings, so that the head portion of the table rises bodily above the
surface of the pulp upon the table. Along the head portion of the table the
riffles form deep channels ; between them, as will be apparent from Fig. 3.
In the neighbourhood of the oblique line 0-0, however, the riffles taper down
nearly to the surface of the table, and continue at a greatly reduced height
through the foot portion of the table surface, as seen in Figs. 4 to 10. In this
manner there are formed a number of channels between the riffles, which channels
have a continuous and uninterrupted bottom from end to end, and have walls
formed by the riffles, at first of a considerable height, and then of a diminished
height. The riffles should not be reduced abruptly, but preferably tapered
through a considerable extent, as shown...
The riffles also widen so as to produce narrower channels between wide flat
surfaces p, as shown clearly in the drawing. As a result of this, the layer of
values lying in the bottom of the channels beneath the sand and lighter particles,
is contracted and deepened by the narrowing of the channels. The sand and
tailings are thereby raised somewhat and readily swept from the values onto the
flat surfaces p and carried off from one to another by the wash water. Moreover,
as the concentration of the values proceeds, the concentrated value occupy less
space, and the narrowing of the channels contributes to the effect desired.
namely that the low-riffles p may rise only just to the top of the layer of
:
concentrates.
In order to produce true rectilinear end-motion without side motion or vertical
motion, we provide brackets r carrying rods s beneath the table and fixed castings t
which have holes accurately fitted to the rods. The rods, therefore, slide in the
castings with true rectilinear motion. The rods r should be exactly parallel
with the riffles. We have found one of the great troubles with existing tables is
a vertical vibration which produces waves in the water on the table. This is
especially true of ball bearings and of hanging links or flexible posts, such as have
Bometimes been used.
The connection for coupling the table to a reciprocating mechanism is indicated
at w, the details being immaterial to our improvements. So also the receptacles
for the tailings, middlings and concentrates are indicated and lettered
respectively x, y, z.
The pulp delivered from the feed-box m onto the head portion of the table, is
subjected to the gentle reciprocating action. As the water flows over from riffle to
riffle, seeking the lower level at the tailings side of the table, it carries with it some
of the sand and light materials. The values, however, travel along the channels
between the riffles with much of the tailings until they reach the reduced portions
of the riffles, where they are preferably met by the wash-water. The wash water
flows obliquely across the table from the water-box n carrying with it nearly all
the waste material, but leaving the values between the low broadened riffles.
Therefore, after the pulp has once been stratified on the head portion of the table
the values are not disturbed by having to pass the ends of any abruptly terminat-
ing riffles. With very rich ores, the layer of values will be proportionately thick
on low riffled portion of the table; so in designing the table, the height of the riffles
on this portion of the table should be such as to extend approximately up to the
top of such layer, and thus allow the valueless portions of the pulp to be washed
off by the water with the least possible disturbance of the values.
The principles of operation as we apprehend them and certain distinctions
between our invention and the prior art, will be best understood by a few brief
comparisons.
First case: If a stream of liquid flows over a stationary bed having slight
transverse narrow depressions widely spaced, a series of slight fixed or stationary

page_text: waves or ripples will be formed, the ripples remaining stationary though the
water flow ever so rapidly; as may be seen in any rapidly flowing shallow river.
Second case: If a stream of water flows gently over a bed having narrow raised
ribs forming dams, so to speak, and particularly if the ribs extend somewhat
diagonally to the inclination of the bed, then the stream is diverted along the
ribs very considerably from the true down-hill line.
Third case: If a regular reciprocation with a quick return movement be given
to a riffled bed in any direction considerably inclined or transverse to the length
of the riffles, then the riffles act as agitators and produce moving waves or swashes
across the riffles, causing the sand, mud and lighter particles more readily to jump
over from riffle to riffle at each swash of the water caused by the reciprocating
movement. At the same time the agitation of the whole fluid mass is very great.
Fourth case: If, however, the line of reciprocating movement is parallel with
the riffes, then the riffles, merely moving lengthwise through the liquid, do not
agitate the liquid and the action on the liquid is very much the same as if the
riffles themselves stood still while the table surface moved to and fro lengthwise
under them. The riffles no longer tend to swash the material across them. The
settling of the values and their travelling action along the channels between the
riffles is therefore more perfect, more positive, and less disturbed. The stratifica-
tion is not disturbed, but is facilitated. The whole action is more thorough.
Our table should preferably embody this last principle of operation. If the
riffles terminate along an oblique line at their foot ends, then the material, after
being stratified and having progressed to the ends of the channels, spreads diagonally
upon the flatter area, permitting the carrying off of the remaining superficial mud
and sand by the wash water. If the riffles diminish in height gradually, instead
of abruptly, then the tendency to form waves at the termination of the riffles,
either by the flow of water around their ends or by the endwise reciprocation of the
riffles, is largely eliminated. If the channels are continued of size only sufficient
to hold the values, then the free washing off of the tailings and slime is most
perfect.
This last case represents the action of our apparatus in its preferred form, when
all the features we have described are combined.
Having now particularly dscribed and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:
1. An ore concentrating table having a lengthwise reciprocating movement and
having raised riffles which diminish gradually in height, so as to avoid abrupt
termination.
2. An ore concentrating table having riffles which are reduced in height
gradually and along an area oblique to the table.
3. An ore concentrating table, having a series of substantially parallel riffles
extending from the head end of the table and reduced in height along an oblique
line or area and continuing at a reduced height towards the foot of the table.
An ore concentrator table, having a series of substantially parallel riffles extend-
ing from the head end of the table and reduced in height and of increased width
before their termination.
5. An ore concentrator table provided with a series of riffles which are of a
constant height for a portion of their length and of a lower height and increased
width for a portion of their foot ends.
6. An ore concentrator table provided with a riffled portion towards its head
and a rough or low-riffled portion towards the foot end, substantially as set forth.
7. An ore concentrator table, of the class having an end-shake movement,
provided with riffles and with a gently-inclined confining or bounding surface for
the water and pulp at the head of the table, whereby the production of waves may
be largely avoided, substantially as set forth.
S. An ore concentrator table of the class having an end-shake movement, pro-

page_text: vided with rifles and mounted on sliding supports that can only move in lines
parallel with the riffles.
Dated this 2nd day of Santambon 1800
or the Applicants,
J. G. LORRAIN, M.I.E.E., M.I. Mech. E.,
Norfolk House, Norfolk Street, London, W.C.,
Chartered Patent Agent.