Electroplating solution recovery system

An electroplating solution recovery system is disclosed which includes an electroplating tank containing an electroplating solution and one or more rinse tanks containing rinse solutions. A tubular interconnection extends between a first of the rinse tanks and the electroplating tank and is operative for transferring rinse solution from the first rinse tank to the electroplating tank by a siphoning process when the level in the plating tank is significantly lower than the level in the rinse tank. Additional tubular interconnections extend between the other rinse tanks for interconnecting them in series relation so that the solution in the tanks is automatically replenished as it is consumed, the solution level in the last tank in the series, however, being replenished from a continuous water supply. Maximum recovery of plating solution is assured by the system, and the pollution levels in the overflow effluent from the last rinse tank are minimized.

BACKGROUND AND SUMMARY OF THE INVENTION 
The instant invention relates to electroplating, and more particularly to a 
novel electroplating solution recovery system wherein liquid is 
automatically transferred between rinse and plating tanks in order to 
achieve maximum electroplating solution recovery and effective pollution 
control and in order to maintain desired liquid levels in the 
electroplating and rinse tanks. 
Electroplating processes are widely used in a variety of industries, 
including the jewelry industry, for providing protective and/or decorative 
platings on various types of articles. In this regard, in most small-scale 
electroplating operations, an article is plated by placing it in an 
electroplating tank containing an electroplating solution of a particular 
metal. The article is then electrically connected to one of two electrodes 
in the tank; and thereafter the electrodes are energized for a 
predetermined period of time to plate the article to a desired extent. 
After the article has been plated, it is disconnected from the respective 
electrode, removed from the tank and dipped in a first rinse tank 
(drag-out tank) to remove excess electroplating solution from the article. 
The article may then be rinsed in one or more additional rinse tanks, 
depending on the particular process. 
During the course of an electroplating operation, portions of both the 
electroplating solution and the rinse solutions are lost from the various 
tanks through carry-over and evaporation as various articles are 
electroplated, and therefore both the electroplating solution and the 
rinse solutions must be frequently replenished. Heretofore, in most cases, 
these solutions have been replenished manually, although systems have been 
heretofore available wherein solutions have been automatically replenished 
through the use of level controls and pumps, etc. In most cases, the 
solution in an electroplating tank has been replenished with rinse 
solution from the first rinse tanks of the system, and the rinse solution 
in the first rinse tank has been replenished with rinse solution from the 
second rinse tank of the system, if there is one, or with water if there 
is only one rinse tank. In this manner, maximum recovery of the 
electroplating solution has been assured, although obviously frequent 
additions of chemicals to the plating tank have been required to maintain 
the necessary concentration therein. 
The instant invention provides a novel electroplating solution system 
wherein liquid is automatically transferred as needed between various 
rinse tanks and between a first rinse tank and a plating tank to 
automatically replenish the solution levels in the various tanks while 
maintaining maximum plating solution recovery. Further, as a result of the 
high degree of effectiveness with which the system of the instant 
invention maximizes plating solution recovery, the amounts of pollutants 
or contaminants contained in waste water effluents from the system are 
effectively minimized. The electroplating solution system of the instant 
invention comprises an electroplating tank containing an electroplating 
solution, a first rinse tank containing a first rinse solution, and a 
first tubular interconnection which extends between the electroplating 
tank and the first rinse tank, so that one end of the first 
interconnection is disposed in the electroplating solution, and the other 
end thereof is disposed in the first rinse solution. In the preferred 
embodiment, the system further comprises a plurality of sequential rinse 
tanks containing sequential rinse solutions and a plurality of tubular 
interconnections which interconnect the various rinse tanks in series 
relation, the first rinse tank in the series, however, also being 
interconnected to the plating tank, as mentioned, and the last tank in the 
series being connected to a water supply for replenishing the solution 
level therein. Also, in the preferred embodiment, the system further 
comprises a check valve connected to the first tubular interconnection 
which permits the flow of liquid from the first rinse tank to the 
electroplating tank, but which prevents the flow of liquid from the 
electroplating tank to the first rinse tank. The electroplating tank and 
the rinse tanks are all disposed at approximately the same vertical 
heights, and all of the interconnections are maintained filled with the 
rinse solutions; and therefore, as the liquid level in the electroplating 
tank decreases, the first rinse solution is automatically transferred 
thereto from the first rinse tank through the first tubular 
interconnection by a siphoning process; and similarly, rinse solutions are 
transferred in series relation between the various other rinse tanks. The 
check valve prevents the flow of liquid from the electroplating tank into 
the first rinse tank, so that contamination of the first rinse solution is 
avoided. However, by using the first rinse solution from the first rinse 
tank to replenish the liquid in the electroplating tank, maximum recovery 
of the electroplating solution from the first rinse tank is assured, 
although obviously, the concentration of the chemicals in the 
electroplating solution must also be replenished from time to time as they 
are consumed in the electroplating process. Similarly, maximum recovery of 
plating solution from the additional rinse tanks is assured as solution is 
automatically transferred in series from tank to tank by siphoning. In any 
case, the instant invention provides an effective electroplating solution 
system wherein the level of the solution in an electroplating tank is 
continuously and automatically replenished. Further, when the 
electroplating solution system is embodied with a plurality of rinse 
tanks, the tanks are connected in sequence with interconnections extending 
therebetween so that the solutions in all of the tanks, with the exception 
of the last tank, are automatically replenished. 
Accordingly, it is a primary object of the instant invention to provide an 
electroplating solution system wherein solution from a rinse tank is 
automatically added to an electroplating tank as required. 
Another object of the instant invention is to provide an automatic 
electroplating solution system which does not require transfer pumps for 
transferring solutions to and from various tanks. 
Another object of the instant invention is to provide an electroplating 
solution system wherein maximum recovery of the electroplating solution is 
assured. 
An even further object of the instant invention is to provide an 
electroplating solution system wherein the chemical pollutants in water 
effluents from the system are minimized. 
Other objects, features and advantages of the invention shall become 
apparent as the description thereof proceeds when considered in connection 
with the accompanying illustrative drawings.

DESCRIPTION OF THE INVENTION 
Referring now to the drawing, a first embodiment of the electroplating 
solution recovery system of the instant invention is illustrated in FIGS. 
1 through 3 and generally indicated at 10 in FIGS. 1 and 3. The system 10 
comprises an electroplating tank 12 containing an electroplating solution 
14, a rinse tank 16 containing a rinse solution 18, a tubular 
interconnection generally indicated at 20 which extends between the 
electroplating tank 12 and the rinse tank 16, and a check valve generally 
indicated at 22 which is attached to the interconnection 20. In operation, 
the rinse solution 18 can pass through the interconnection 20 into the 
electroplating tank 12 where it is intermixed with the electroplating 
solution 14. However, the check valve 22 prevents the reverse flow of 
liquid through the interconnection 20 so that the electroplating solution 
14 cannot pass through the interconnection 20 into the rinse tank 16 and 
become mixed with the rinse solution 18 contained therein. 
The electroplating tank 12 and the rinse tank 16 may be of any suitable 
durable constructions, such as molded fiberglass, etc., the electroplating 
tank 12 being adapted for use in electroplating operations and therefore 
being constructed in accordance with known construction techniques to make 
it suitable for such applications. The system 10 includes only a single 
rinse tank 16, although it will be understood that other embodiments of 
the system of the instant invention which include additional rinse tanks 
which are disposed in series relation with the tank 16 and which 
communicate in series through additional interconnections 20 with the 
rinse tank 16 are contemplated, as will hereinafter be set forth. 
The interconnection 20 has first and second ends 24 and 26, respectively, 
which are disposed in the plating and rinse tanks 12 and 16, respectively, 
so that they are beneath the surfaces of the plating and rinse solutions 
14 and 18, respectively. The interconnection 20 preferably comprises an 
inverted tubular U-shaped portion 28 which is positioned so that one end 
thereof is disposed beneath the surface of the plating solution 14 in the 
plating tank 12 and so that the other end thereof is disposed beneath the 
surface of the rinse solution 18 in the rinse tank 16. The interconnection 
20 preferably further comprises end portions 30 which extend upwardly from 
the opposite ends of the U-shaped portion 28 in the solutions 14 and 18 
and define the ends 24 and 26 of the interconnection 20. The check valve 
22 is preferably attached to the second end 26, and therefore it is 
preferably disposed in the rinse solution 18. 
The check valve 22 as herein embodied comprises a body portion 32 having a 
tapered circular opening 34 therethrough. The check valve 22 is secured to 
the end 26 so that the interconnection 20 communicates with the opening 34 
and so that the opening 34 tapers upwardly, and an O-ring 36 is provided 
in the body portion 32 adjacent the upper end of the opening 34. A buoyant 
ball element 38 is received in the opening 34 and is dimensioned so that 
it can pass freely in the lower portion thereof but so that it is 
sealingly receivable against the O-ring 36 in the upper portion of the 
opening 34. The buoyant characteristic of the ball element 38 normally 
biases it to a position of sealing engagement against the O-ring 36, 
whereby the flow of liquid upwardly through the passage 34 is prevented. 
However, as will be seen, the ball element 38 can easily be dislodged from 
its position of sealing engagement with the O-ring 36 by the application 
of downward pressure on the ball element 38 such as caused by a situation 
wherein the level of the rinse solution 18 in the rinse tank 16 is higher 
than the level of the plating solution 14 in the plating tank 12. 
During operation and use of the system 10, a conventional plating solution 
14 is provided in the tank 12, and conventional electroplating electrodes 
(not shown) are also provided in the plating tank 12. A rinse solution 18 
is provided in the rinse tank 16, the rinse solution, in most instances, 
comprising water with a certain amount of plating solution 14 intermixed 
therewith resulting from carry-over with plated articles from the plating 
tank 12. The interconnection 20 is positioned between the plating and 
rinse tanks 12 and 16, respectively, so that the end 24 is beneath the 
surface of the solution 14 and so that the end 26 and the check valve 22 
are beneath the surface of the rinse solution 18. During start-up of the 
system 10, the interconnection 20 is primed to render the system 10 
operative, i.e., it is filled with a liquid so that solution from the 
rinse tank 16 can pass therethrough into the plating tank 12 by a 
siphoning process, and thereafter the interconnection is maintained filled 
with solution. Since the normal flow through the interconnection 20 under 
operating conditions is from the rinse tank 16 into the plating tank 12, 
during operation of the system 10 the solution in the interconnection 20 
normally comprises the rinse solution 18; but because the interconnection 
20 communicates with the plating tank 12 through the open end 24, the 
actual concentration of electroplating chemicals in the solution in the 
interconnection 20 may be slightly higher than in the solution 18 in the 
rinse tank 16. In operation, the level of the rinse solution 18 in the 
rinse tank 16 is normally controlled either by continuously adding water 
thereto, so that the excess passes through an overflow (not shown) in the 
rinse tank 16, or by continuously replacing the rinse solution 18 with 
solution from a secondary rinse tank (not shown). As the level of the 
plating solution 14 in the plating tank 12 drops as it is consumed in the 
plating operation and also as it evaporates, rinse solution 18 
automatically flows through the interconnection 20 into the plating tank 
12 to replenish the level of the plating solution 14 in the plating tank 
12 until equilibrium conditions are reached. In this regard, in 
applications where the densities of the plating solution 14 and the rinse 
solution 18 are substantially equal, the levels in the plating and rinse 
tanks 12 and 16, respectively, will be maintained at substantially equal 
levels by siphoning through the interconnection 20. However, when plating 
with relatively heavy plating solutions, the level in the plating tank 12 
is normally somewhat lower than the level in the rinse tank 16 at 
equilibrium conditions as a result of the differences in the densities of 
the two solutions. 
During operation of the system 10, an article to be plated is placed in the 
plating tank 12 and connected to the appropriate electrode, and the two 
electrodes in the tank are energized to effect electroplating of the 
article. Thereafter, the article is removed from the plating tank 12 and 
placed in the rinse tank 16 where solution 14 from the plating tank 12 is 
rinsed off. As the level of the plating solution 14 in the plating tank 12 
drops due to carryover and evaporation, the solution 14 is automatically 
replenished with rinse solution 18 from the rinse tank 16. In this regard, 
even if the level of the plating solution 14 or the level of the rinse 
solution 18 should inadvertently fall sufficiently to expose either or 
both of the ends 24 and 26, the interconnection 20 will normally remain 
filled with solution because of the upwardly extending ends 30. In any 
case, since rinse solution 18 is used to replenish the level in the 
electroplating tank 12, most of the electroplating solution 14 carried 
over with the electroplated article into the rinse tank 16 is recovered 
and eventually returned to the electroplating tank 12. Obviously, the 
concentration of the electroplating solution 14 in the tank 12 must, 
however, from time to time be increased by adding additional 
electroplating chemicals, but maximum recovery of these chemicals is 
assured by the system 10. 
A second embodiment of the electroplating solution recovery system of the 
instant invention is illustrated in FIGS. 4 and 5 and generally indicated 
at 40. The system 40 comprises an elongated electroplating tank 42, an 
elongated first rinse or drag-out tank 44, and second, third, and fourth 
rinse tanks 46, 48 and 50, respectively. The plating tank 42 contains a 
plating solution 52, and the rinse tanks 44, 46, 48, and 50 contain first, 
second, third, and fourth rinse solutions 54, 56, 58 and 60, respectively. 
The tanks 42, 44, 46 and 48 are preferably constructed of suitable durable 
construction materials, such as fiberglass, in a manner generally known in 
the plating industry. The tanks 44, 46, 48 and 50 are integrally formed in 
the system 40 as herein embodied, and an integrally formed inner weir 62 
is provided in the fourth rinse tank 50, the area defined by the weir 62 
communicating with a drain 63. Extending between the plating tank 42 and 
the first rinse tank 44 is an interconnection 20 of the type hereinabove 
described for the system 10, and extending between the first rinse tank 44 
and the second rinse tank 46 is a tubular interconnection 64 which is 
similar to the interconnection 20 but which does not include a check valve 
22. Tubular interconnections 64 are also provided extending between the 
second rinse tank 46 and the third rinse tank 48 and between the third 
rinse tank 48 and the fourth rinse tank 50. A water inlet line 66 extends 
from a valve 68 into the third rinse tank 50 as illustrated for supplying 
water thereto at a controlled rate. 
In operation of the system 40, electrodes are provided in the plating tank 
42 for plating an article in a manner similar to that described for the 
system 10. After the article has been plated in the tank 42, it is removed 
therefrom and placed into the first rinse tank 44. The article is then 
sequentially dipped in the second, third and fourth rinse tanks 46, 48 and 
50 to remove any residual plating solution from the article. During 
operation of the system 40, liquid is automatically transferred from the 
fourth rinse tank 50 to the third rinse tank 48, from the third rinse tank 
48 to the second rinse tank 46, from the second rinse tank 46 to the first 
rinse tank 44, and from the first rinse tank 44 to the plating tank 42. 
These transfers of solutions are effected by siphoning with the tubular 
interconnections 64 and 20 so that the levels of the plating solution 52, 
and the first, second and third rinse solutions 54, 56 and 58 are 
automatically replenished. The level of the fourth rinse solution 60 in 
the fourth tank 50 is automatically replenished with water from the water 
supply tube 66, excess solution from the tank 50 spilling out over the 
weir 62 and passing into the drain 63 to maintain the fourth rinse 
solution 60 in the fourth rinse tank 50 at a level which is approximately 
equal to the top of the weir 62. In this connection, preferably the inflow 
of water from the supply tube 66 is maintained at a reduced rate so that 
only minimal amounts of fourth rinse solution 60 are spilled over the weir 
62 whereby the amount of water consumed in the system 40 is minimized. 
However, even when the flow of water through the inlet line 66 is 
minimized, the concentration of the electroplating chemicals in the fourth 
rinse solution 60 is maintained at a reduced level so that the solution 
passing out through the drain 63 can be safely disposed of without concern 
with regard to water pollution. Again, since the interconnections 20 and 
64 all have inwardly extending ends 30, even if the levels of one or more 
of the solutions 52, 54, 56, 58 and 60 should inadvertently fall 
sufficiently to expose one or both of the ends of one or more of the 
interconnections 20 and 64, the interconnection 20 or 64 will remain 
primed. 
It is seen, therefore, that the instant invention provides an effective 
electroplating solution system wherein solution is automatically 
transferred from one or more rinse tanks to a plating tank without the use 
of level controls, pumps, and the like and is operative with reduced 
pollution levels. The system of the instant invention also provides for 
maximum recovery of electroplating chemicals. For these reasons, as well 
as the other reasons hereinabove set forth, the instant invention 
represents a significant advancement in the art which has substantial 
commercial merit. 
While there is shown and described herein certain specific structure 
embodying the invention, it will be manifest to those skilled in the art 
that various modifications and rearrangements of the parts may be made 
without departing from the spirit and scope of the underlying inventive 
concept and that the same is not limited to the particular forms herein 
shown and described except insofar as indicated by the scope of the 
appended claims.