FR2554614A1 - Method permitting sequential processing of liquids, principally by electrolysis, whatever the variations in arrival flow rate - Google Patents

Abstract

The invention is principally in the field of recovery electrolysis. It makes it possible to modify the sporadic flow rate of a removed liquid in order to permit optimum treatment of it in a sequential form (the latter being imperative). During the time necessary for treatment of the liquid given off, a solenoid valve prevents admission of new liquid by trapping it in a buffer vessel. The start of the cycle, controlled by a level detector, starts up for a time which is programmed according to requirements until removal of the treated liquid before restarting a new cycle. Various additions make it possible to vary the processing times or on their time lag. The invention is suitable for permitting complete electrolytic recovery from erratic flow rates (for example).

Description

The present invention relates to the technical field of recovery electrolysis used in photography and in radiology and where it is necessary for complete recovery to maintain a certain volume of liquid for a determined time in a treatment area then rrcme that the flow of liquid upstream of the electrolytic cell is variable.

In certain prior devices, the continuous aspect of electrolysis was characterized by the fact that the admission of a certain quantity of liquid to electrolysis resulted in the simultaneous evacuation by overflow of an equal quantity of liquid.

The unsuitability for variations in flow forced the use of low amperage to avoid sulfurization at times of low flow with, as a corollary, only partial recovery at times of high flow.

In other prior devices the transformation of the erratic arrival of the liquid to be treated did not eliminate the elimination by overflow of a certain quantity of liquid not yet treated by electrolysis.

The technical problem to be solved was to transform the variable inlet of the liquid to be electrolyzed into sequential treatment without allowing the evacuation of untreated or insufficiently treated liquid. The desirable rapidity of electrolysis leads to the use of a relatively high amperage and, in order to avoid secondary chemical manifestations, rotation of the cathode. This rotation movement of the cathode being liable to annoy users by its noise , a delay device will be attached whenever it is desirable,
To solve this problem, the liquid to be treated is admitted into the electrolysis tank in sequences of a duration adjustable from a time necessary for the withdrawal of all of the metal to be recovered while the liquid subsequently admitted is stored in a tank. buffer.

To do this, the liquid enters the device, passes by gravity through the first tank (buffer) separated from the electrolysis tank by a solenoid valve n "1 in the open position.

The rise in the level of the liquid in the electrolysis tank triggers, when the predetermined quantity is reached, the following operating cycle 1 ") closing of the solenoid valve n01; 20) starting the rotation motor cathode and the electrolysis function for a duration pre-programmed on a timer depending on the metal content of the electrolytr; 3) possibly starting the delayed start of rotation of the cathode and the electrolysis function ;; 4) otherwise, when the electrolysis function and cathode rotation have stopped after the required time delay, 50) opening of the solenoid valve no. 2 and evacuation by gravity of the dekaréssé liquid in all of the metal initially contained; 6) closing of the electrovalve n 2 making the electrolysis tank operational; 7) opening of solenoid valve n01 and restarting the cycle.

There is obviously a match between the volume of the buffer tank and the electrolysis time.

This process, object of the invention, can be used in all cases where it is necessary to transform the sporadic arrival of a moving liquid allowing the sequential processing of said liquid.

Particularly interesting applications can be found in the field of silver-metal recovery in fixative baths used in photography and radiology.

Claims (2)

 1 ") Process for transforming a naturally variable liquid flow into a sequential flow, characterized by the use of two superimposed tanks. connected to each other by a solenoid valve; the latter, normally open, closes when a level detector commands it from a liquid level reached in the secondary tank; closing this solenoid valve also triggers a treatment and evacuation cycle before returning to the waiting point for the start of a new cycle.  2 ") Method for transforming a continuous flow into a sequential flow according to claim n" l, characterized in that it allows the use of three parameters which are impossible to control in continuous processing: one minuteSEe allowing intervention on time electrolysis, a pressure switch to intervene on the intensity of the electrolysis current, the positioning of the evacuation solenoid valve to act on the concentration of the product to be treated in metal ions.