Liquid purification or separation – Processes – Separating
Reexamination Certificate
1999-03-16
2001-07-31
Popovics, Robert (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S634000, C210S511000, C210S248000, C210S197000, C210S532100, C210S540000
Reexamination Certificate
active
06267900
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method for adjusting the boundary surface or the location of the dispersion zone in the vertical direction in liquid—liquid extraction, in between two solutions that are mutually separable owing to gravity, and to a method for conducting the separated solutions out of the space where the separation takes place, advantageously so that an aeration of the solutions in the transfer step is prevented. The invention also relates to an apparatus for realizing the method.
BACKGROUND OF THE INVENTION
In large extraction plants, such as copper extraction, the adjusting of the solution boundary surfaces and the discharging of the solutions are combined by adopting two collecting chutes provided with solution overflows, which chutes extend vertically over the whole final end of the separation part. Generally there are used two attached chutes, the first of which—in the solution flow direction—is a fixed chute collecting the lighter organic solution as overflow, and the latter is a chute collecting the aqueous solution, provided with an adjustable overflow edge. The heavier solution, i.e. the aqueous solution, is conducted from underneath both chutes through a duct formed in between the chute bottoms and the separation part bottom. From this duct, the aqueous solution turns up and flows in the form of a U-turn in the collecting chute, in a direction that is opposite to the original flowing direction.
The adjustable overflow of the aqueous solution is formed of an outer edge of an aqueous solution chute, known in the prior art, which is constructed of a wall plate extending up to a given height and of another plate moving against it. This structure, provided with a horizontal overflow edge, serves as the basic overflow level, arranged at a height which it is unnecessary to go below from the adjusting point of view. The adjusting range proper locates above this level, and it is taken care of by means of a movable plate part, the overflow edge of which is likewise maintained in horizontal position.
The above described aqueous solution chutes provided with overflow edges include some drawbacks. Two plates moving against each other cannot be made compact, but a remarkable part of the overflow, about 10-40% thereof, passes along some other route than over the overflow edge. Therefore the adjusting of the phase boundary surface works properly only when the solution feeds surpass about half of the amount for which the extraction plants are designed. Moreover, when driving down the process, the above described overflow causes a solution flow to the next process step and thus weakens the extraction results in connection with the next drive up. There is also the danger that the boundary surfaces of the separation parts fluctuate, in which case a phase dispersion carrying impurities and located in between pure phases is transported along with the separated solutions.
SUMMARY OF THE INVENTION
By means of the method and apparatus of the present invention, we have now attempted to avoid the above described drawbacks, and the object is to improve the accuracy in the adjusting of the boundary surface in between the solutions, and at the same time prevent an aeration of the solutions and thus to improve the controllability of the flow of the separating solutions. A good adjustability is particularly important with liquid—liquid extraction, when driving the process up an down. According to the invention, the boundary surface between the solutions is adjusted by adjusting the overflow surface, so that in the bottom part of the aqueous solution end, there are installed several vertically adjustable tubular members, whereto the aqueous solution flows from the downwardly direction and is discharged to the surrounding aqueous solution chute through the top element of the tubular member. The aeration of separated solutions is prevented by means of a structure where the settled solution flows from the solution end via a shaft-like weir box positioned lower than the bottom of the solution end to the tubular lines. The prevention of aeration is important particularly for the extraction solution. Said weir box can also be provided with additional structures for avoiding the creation of vortexes and the absorption of air into the solution through them. The essential novel features of the invention are apparent from the appended patent claims.
REFERENCES:
patent: 4015629 (1977-04-01), Morgan et al.
patent: 4212740 (1980-07-01), Greene
patent: 5143605 (1992-09-01), Masciarelli
patent: 5275721 (1994-01-01), Mathews
patent: 5413707 (1995-05-01), Shatilov
patent: 6083400 (2000-07-01), Nyman et al.
Hultholm Stig-Erik
Kuusisto Raimo
Lilja Launo
Lyyra Juhani
Nyman Bror
Morgan & Finnegan , LLP
Outokumpu Technology OYJ
Popovics Robert
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