Metal separating process and apparatus

Heavy metals such as mercury, gold, platinum, rhodium, osmium, silver, lead, palladium, etc., in the free state, are separated from their ore by applying water and the ore to a plurality of two to six rotating, inclined, spiral grooved wheels driven from a common shaft. The grooves are closely spaced and may have a declining pitch from the wheel at its periphery to its central annulus. The free metal tends to sink to the bottom of the grooves and the lighter ore is washed away as the metal moves along the spiral grooves to the annulus. The free metal and any remaining ore is fed from the annulus to the succeeding wheel and the process is repeated. Mercury may be added to any of the wheels to facilitate separation of the metal from the ore. A separating wheel having a unique groove design is also disclosed.

BACKGROUND OF THE INVENTION 
This invention relates to a process and apparatus for separating heavy 
metals such as mercury, gold, platinum, lead, rhodium, osmium, palladium, 
silver, etc., in the free state from their associated ores. In some 
instances, the metal may be present in mine tailings which heretofore had 
little, if any, commercial value because of the large recovery costs, and 
hence were abandoned. In other instances, the metal may be present in a 
natural occurring ore body, but not of sufficient size to permit economic 
recovery by conventional processes. 
Various types of apparatus have in the past been employed to recover 
precious metals such as gold from mine tailings raw ore, etc., using water 
washing techniques. One type of apparatus employed an inclined grooved 
wheel separator to which was fed a supply of ore that was then water 
washed. Gold particles sank to the bottom of the grooves, and when the 
wheel was rotated, the gold was moved upwardly along the grooves from the 
periphery of the wheel to a central orifice where it was recovered. 
The basic problems when using a single wheel device or a plurality of such 
devices involved the necessity of feed augers for every wheel and the 
necessity for maintaining a uniform feed to each wheel. Also, once the 
beneficiated ore was removed from a wheel, it tended to dry out in a non 
uniform fashion; this made it difficult to feed it uniformly to a 
succeeding wheel even when employing a mechanical device such as an auger. 
Furthermore, the use of a plurality of single separator wheel devices 
produced a spectrum of ore grades each of which had to be treated 
differently. 
Consequently, the various prior art devices were limited in overall 
efficiency and many bodies of ore tailings still exist which contain gold 
and other precious metals but which heretofore could not be further 
economically refined with the available apparatus. 
In Applicant's copending U.S. application Ser. No. 613,366, filed Sept. 15, 
1975 now U.S. Pat. No. 4,008,152, there is disclosed a process and 
apparatus for separating heavy metals from ore employing at least three 
separator wheels driven from a common mounting. 
However, when capital costs are included, the separator wheels are an 
expensive component of the apparatus. 
It is therefore an object of this invention to employ fewer separator 
wheels and still retain the essential benefits of the invention disclosed 
in my copending application without undue detriment to process economics. 
Another object is to provide wash water actuation which coincides with 
operation of the separator wheels. 
Another object is to provide simultaneous alteration of the wheel 
inclination when in operation. 
Another object is to augment the separating action by employing mercury as 
a phase separator. 
Another object is to provide simultaneous operation of the wheels and wash 
water pumping and also to permit disengagement of the wheels from the 
drive shaft while still continuing to apply wash water to the separator 
wheels. 
Another object is to provide a separator wheel with a unique groove design. 
Other objects of this invention will become apparent from the description 
and drawings to follow. 
SUMMARY OF THE INVENTION 
According to the invention, the process and apparatus therefor provides at 
least two inclined, commonly driven, grooved wheels, each wheel having an 
outer rim to retain an ore slurry on the wheel surface. The groove are 
tightly packed with a minimum of flat surface between each groove so that 
the free flow of dressing water is not a significant factor in the 
process. The grooves are spiralled inwardly, usually with a declining 
pitch, and terminate in a central annulus which leads to a downwardly 
inclined feed pipe or funnel. 
A succeeding wheel is fed directly from the funnel, with at as a two 
wheels, and as many as six wheels being employed. The number of wheels 
used depend on such factors as the concentration of metal in the ore, the 
mesh size of the ore, wheel speed, wheel size, groove spacing and design, 
the amount of water applied, the cohesiveness of the ore, etc. For 
example, a concentrate or a free-flowing sand having a high gold content 
could employ only two separator wheels without undue loss of efficiency. A 
water feed system is utilized to produce a slurry by applying water to the 
ore. This causes the heavy gold or other precious metal particles to 
settle to the bottom of the grooves and be rotated toward the center 
annulus of the wheel along with some ore as slurry concentrate. The slurry 
is fed to the funnel and gravitates downwardly to the succeeding wheel 
where the process is repeated. After successive treatments with at least 
two wheels and as many as six wheels, if necessary a highly concentrated 
ore, such as gold ore, is produced. 
The process is not only continuous, rather than being a batch operation, 
but also it can be continuously controlled by regulating: a) the weight 
and volume of initial ore feed to the first wheel; b) the amount of water 
supplied; c) the inclination and; d) the rotational speed of the wheels. 
This permits the production not only of a concentrated ore, but also 
results in a high recovery which in many cases varies from about 95%-99%. 
Furthermore, the effect of feeding a slurry of beneficiated ore through 
the centrally located feed funnel totally eliminates the requirements of 
feed augers from wheel to wheel by producing a controlled flow of slurry 
during separation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIG. 1, the separator is shown mounted on vertical support pipes 10, 11. 
A horizontal, hollow support bar 12 is mounted (e.g. flexibly) at one end 
on support pipe 10, the horizontal bar being vertically adjustable along 
the pipe 10 by a clamp 13, or by hydraulic means, etc. A feed hopper 17 
having a screen cover 20 is mounted on support pipe 11; the hollow, 
horizontal bar 12 is mounted at its other end to the feed hopper. It will 
be appreciated that the feed hopper and screen may be eliminated and this 
would permit the first separator wheel to be mounted in the same manner as 
the remaining wheel or wheels; a simple screen would then be provided for 
the first wheel. 
A rotatable drive shaft 21 is mounted within the horizontal bar 12, the 
shaft being driven by a motor 22 through a speed reducer in mounting 
bracket 25; a water pump (not shown) in the bracket 25 is powered from the 
motor and delivers water to spray bars, one spray bar 26 being shown. 
A plurality of rotatable separator wheels 32, 33 and 34 are serially 
disposed for rotation by the drive shaft 21. Separator wheels 32, 33 are 
attached to brackets 35, 36 mounted on the horizontal bar 12 while 
separator wheel 34 is mounted to the hopper 17. The separator wheels are 
driven by roller drives 37, 38 and 39 which are mounted on the drive shaft 
21 and rotated thereby. The separator wheels are preferably flat and 
pan-shaped to facilitate a serial mounting along the horizontal bar 12; 
the wheels are rotatably mounted on shafts 42, 43 and 44 respectively, and 
provide a plurality of spiral grooves 45 on their upper surfaces. Ribs 47 
which terminate in a hub 48, reinforce the wheels. An annulus funnel 49 
along each hub permits concentrate slurry to pass therethrough to a 
succeeding wheel. As noted, a separator wheel including grooves, ribs and 
annulus funnel, may be integrally formed from a molded plastic. Typical 
plastic materials include: polyurethane, epoxy, nylon, polyester, 
polyethylene, polypropylene, various rubbers, etc; fillers may be employed 
where required. 
An outer rim 50, which may be integral with the wheel or constructed of 
similar materials as the wheel, retains ore on the wheel while it is 
broken down by water into a slurry for separation by the wheel into an 
upgraded ore and lean ore. The outer rim also functions to frictionally 
engage roller drives 37, 38 and 39 and is driven therefrom. If desired, 
the separator wheels may be urged against the roller drives by support 
wheels, two wheels 54, 55 being shown. The rotation of separator wheel 34 
rotates gears 56, 57 through a belt 58 and this in turn rotates a feed 
auger 59 mounted at the bottom of the feed hopper 17; this embodiment is 
employed when a positive feed is required. However, a free flow or a 
gravity feed of the ore may be employed either alone or in conjunction 
with a metering valve at the hopper outlet. The wheels 32, 33 and 34 are 
adjustably inclined to the horizontal with a decreasing angle; typical 
inclinations for each wheel are about 120.degree.-150.degree. , 
120.degree.-140.degree. and 100.degree.-125.degree., respectively. During 
operation of the separator, it is usually desirable to adjust the wheel 
inclinations depending on load, type and quality of ore, water 
availability, etc. However, it is preferred, when adjusting the wheel 
inclinations, to adjust them simultaneously and thereby maintain the ratio 
of the wheel inclinations generally the same. This accomplished by 
vertical movement of the clamp 13. Elevation of the clamp pivots the 
horizontal bar 12 and the hopper 17 about pipe 11 which in turn will 
increase the angle of wheel inclination to the horizontal; lowering the 
clamp increases the angle of wheel inclination. 
The grooves of the separator wheels may be saw-toothed as shown in FIG. 1; 
however, a preferred groove configuration is shown in FIG. 2. The grooves 
60 provide trailing, curved portions 61 shaped somewhat like an airfoil, 
curved leading corners 62 and a lifting face 63 inclined approximately 
perpendicularly to wheel base 64. As the grooves travel from the wheel 
periphery 66 to the annulus at the center 65, the curved portion 61 
becomes more flat and the corners 62 become sharper and somewhat 
saw-toothed 61a cross-section. The air-foil configurated grooves comprise 
about about 60%-85% of the total grooves measured along the wheel radius. 
The groove design of FIG. 2 greatly reduces turbulence which occurs when 
using sharp saw-tooth grooves. Hence, when the wash water breaks down the 
ore into a slurry on the moving wheel, the airfoil grooves prevent fine 
metal particles which have settled in the bottom of a groove to be removed 
by turbulence; this permits a more efficient and uniform separation of 
metal from the ore. 
Wash water employed to slurry the raw ore is supplied from a water pump 
within the bracket 25 and then through spray bars to the separator wheels 
32, 33 and 34 via water valves 67, 68 and 69 and through ducts 67a, 68a 
and 69a respectively. Generally, wash water for the separator wheels is 
supplied in a similar fashion to that shown in my copending application, 
U.S. Ser. No. 613,366, now U.S. Pat. No. 4,008,152. The valves and spray 
bars may be individually adjusted to regulate the appropriate amount of 
water supplied to each separator wheel. 
If desired, a mercury amalgamating system 70 may be employed. It includes a 
fine screen 71 mounted on the hub of separator wheel 32, a mercury 
collector 72, and a recycling line 73 leading to wheel 32 (or any of the 
wheels) at its periphery. Mercury is slowly fed automatically or manually 
to the separator wheel causing precious metals such as gold, silver, etc. 
to amalgamate with the mercury, form a dispersion therewith or sink to the 
bottom of the mercury. The lighter ore and water float on the mercury 
surface and consequently will be more easily separated from the values 
such as gold, silver, etc. Upon reaching the screen 71, the mercury will 
pass through the screen into the collector 72 and will be recycled. The 
coarser concentrate passes along the screen into collector 74 and is 
eventually recovered. Any fine gold or other values which pass through the 
screen along with the mercury may be recovered by evaporation of the 
mercury at intervals. Gold trapped in the screen itself may be recovered 
by suitable techniques. 
Various types of ore which may be refined by the apparatus and process of 
this invention include: alluvial deposits, tailings, raw ore, gravel, 
concentrate, sand, sluice box washings, etc., and collectively are 
referred to as raw ore. 
In operation, the separator wheels are started up by actuating the motor 22 
which simultaneously supplies water through the pump 26 and to the 
separator wheels. Raw ore is then fed through the screen 20 to the feed 
hopper 17 and then fed by the auger 59 or by gravity to the periphery of 
the separator wheel 34 at its downwardly moving side. The raw ore is 
slurried by the water causing the heavy metal to fall to the bottom of the 
grooves 45. The lighter waste ore is washed over the top of the grooves 
and collects in a pool at the wheel periphery and eventually overflows and 
is passed to waste or further recycling. The heavier particles and a minor 
amount of ore are passed upwardly along the spiral grooves to the annulus 
funnel 49 and by the same process to the succeeding wheels 32, 33. Heavy 
metal such as gold, lead, etc., become concentrated while the light ore is 
separated and discharged to waste. A suitable type of discharge means is 
described in my now copending application, supra, now U.S. Pat. No. 
4,008,152, and hence is omitted for convenience. During operation, the 
motor 22 may be disengaged from the drive shaft 21 while still applying 
wash water. This permits the wheel to be cleaned while preventing ore from 
entering the separator through the auger 59. Also, the separator can be 
maneuvered without endangering the operator since the wheels are not 
rotating. 
The final concentrate, with or without the use of mercury to augment the 
process, is forwarded to the collector 74 and then upgraded to the pure 
metal. It will be appreciated that the rim-driven separator wheel of the 
present invention is preferable to that of a center-driven shaft since the 
wheel inclinations can be adjusted simultaneously. Furthermore, the use of 
shafts, drive belts, gears, etc., has been reduced. Also the additional 
clearance provided by removing belts, and drive shafts from the vicinity 
of the wheel eliminates problems due to water and ore splashed in these 
components and provides a lighter apparatus for easier transportation; 
also, for assembly. 
Overall, the apparatus of this invention is simplified and more flexible 
compared to that in my copending application, supra, now U.S. Pat. No. 
4,008,152. 
Finally, various adjustments such as simultaneously varying the wheel 
inclination, motor and drive shaft disengagement, auger feed, phase 
separation using mercury, etc., permit the apparatus, and hence the 
process, to be more efficient and also to be more easily and safely 
operated than previously.