SU939595A1 - Electrolyzer for producing iron hydroxide - Google Patents

Description

(54) ELECTROLYSER TO GET IRON HYDROXIDE

The invention is also intended to produce iron hydroxide by the electrochemical dissolution of iron.

A device for the electrochemical dissolution of iron is known, which is a monopolar electrolyzer having steel electrodes immersed in an electrolyte solution. Conducting electrolysis leads to anodic dissolution of iron 1.

The disadvantages of monopolar electrolyzers are cumbersome, a large number of electrical connections, the need to have a DC source for high current loads and a low voltage, which increases the cost of the entire installation.

A known electrolyzer for producing iron hydroxide, comprising a cylindrical body, concentrically arranged cylinder-shaped electrodes, on the side surface of which there are holes C2.

The disadvantage of this device is that the formation of iron hydroxide is associated with the dissolution of the electrodes, which necessitates their periodic replacement. Rigid mounting of electrodes in an insulated bottom

corps makes this operation difficult and low-tech.

As the iron dissolves in the cells, iron hydroxide will accumulate, which must be removed from the cell, but its design only allows it to be done periodically.

The heat released during the electrolysis process is removed from the apparatus through the outer wall of the housing, which causes great difficulties due to the small amount of heat transfer surface. To provide a heat sink, copper radiators, forced air blowing, etc. are provided in the electrolyzer, which significantly complicates the design of the device.

The purpose of the invention is to increase the productivity of the electrolyzer and simplify its maintenance.

The goal is achieved in an electrolytic cell to produce iron hydroxide including a cylindrical body, concentrically arranged cylinder electrodes with openings on the side surface, each of the electrodes is provided with a bottom, the electrolyzer is equipped with gaskets placed between the bottoms of the electrodes, and the height of the gaskets refers to the distance between side surfaces of the electrodes as the thickness of the bottom to the thickness of the walls of the electrodes, and the holes are made transversely in the lower and upper parts of the electrodes The poison area and the total hole area of each electrode is 0.5-1% of its side surface area.

The drawing shows a diagram of the device.

The device includes steel cylindrical cup electrodes 1 with holes 2 for the circulation of electrolyte, drain fitting 3, current leads 4 and insulating gaskets 5.

The outer electrode is the cathode and the smallest electrode is the anode. The electrodes located between the monopolar electrodes work as bipolar, the anodes being the outer surfaces of the electrodes. In the upper part of the outer electrode there is a drain fitting. The electrode of the smallest diameter has an opening for supplying electrolyte to the electrolyzer. In the walls of the bipolar electrodes, there are holes arranged alternately in the lower and upper parts of these electrodes.

The area of each hole is 0.5-1% of the side surface area of each electrode. All of these holes serve, first, to ensure the same level of electrolyte in the cells of the electrolyzer, secondly, to continuously drain the hydroxide from the apparatus, and third, to ensure. heat removal from the electrolyzer by continuous circulation of the electrolyte. Through the holes in the electrodes a leakage of current occurs, i.e. The so-called stray currents appear, which are not expended on the main process of dissolving the gelea, and the greater the leakage current, the more the output of the main products decreases, and the more the power consumption increases. This means that the area of the holes must be within such limits that the leakage current is minimal while ensuring the normal circulation of the solution.

If the holes with an area of less than 0.5, then in this electrolyzer, the hole in the hydroxide precipitates the iron hydroxide to the bottom and stops the electrolyzer.

If you increase the area of the holes more than 1%, the performance of the cell will fall sharply. When the distance between the side surfaces of the electrodes is greater than the height of the gaskets.

then the current density on the bottom is higher, since with a decrease in the distance between the bottoms, the electrical resistance of the column fixed between these surfaces of the liquid column decreases accordingly and the current on the bottom increases (respectively, the current density). An increase in current density leads to a more intensive dissolution of the bottom surface. If in this case the bottom thickness is increased, then the distance between the bottoms can be reduced, depending on:

e fAHd h fs

where P is the distance between the side surfaces of the electrodes; h is the thickness of the gasket;

Jaano

electrode bottom thickness; wall thickness of the lateral electric rod.

Thus, the height of the gaskets may be less than the distance between the side surfaces, but the thickness of the bottom of the electrodes must be increased.

To ensure continuous operation of the device, fresh portions of the electrolyte are introduced into the apparatus through the opening of the electrode of the smallest diameter. 0 The amount of fresh solution supplied to the device is determined by two conditions: the concentration of hydroxide, gel in the solution flowing from the device should not exceed 5–40 kg / m, the electrolyte temperature should not exceed 6–70 ° C.

When the concentration of iron hydroxide is more than 40 kg / m, the solution is poorly transported, which may cause iron hydroxide to block the cells and uneven dissolution of the side walls of the electrodes.

The proposed device completely ensures the removal of heat from the device, which allows it to provide the necessary current load and achieve high performance.

The technical advantages of the developed device in comparison with the known one is to simplify its maintenance, as well as to ensure the continuity of the electrolysis process. These advantages are achieved by the non-rigid installation of the electrodes by creating conditions for the continuous circulation of the electrolyte.

Claims (2)

1. Zaretsky S.A. and others. {Technologists of electrochemical production M., Higher School, 1970, p. 30-32. 2. The patent of Great Britain 1483203, cl. From 25 to 9/00, published. 08.17.77