IL31367A - Electrolytic bromine production - Google Patents

Description

4 production THE STATE OP Atomic Energy The present invention concerns a method for the electrolytic production of bromine from bromide Conventionally bromine is produced from natural bitterns or ocean water by processes which comprise oxidation of the bromide to bromine and the removal of bromine from the Oxidation usually carried out by means of rine so that a source of chlorine has to be For the of the after it is to employ either the steaming out the or out with Native bromide water from the Dead Sea usually contain magnesium and calcium If such brine is submitted to the sodium ions migrating to the immediately reset there with water to form sodium hydroxide with the result that the is raised and the solution that is being lysed turns In consequence any bromine ing at the anode immediately reacts with the sodium hydroxide to sodium This difficulty for not bo solved by of a semipermeable partition dividing the vessel in which tho electrolysis is carried out into anode and cathode compartments and preventing the bromine formed in the former from migrating to the since any such tition immediately be clogged by magnesium and c lcium hydroxide can the difficulty be by using a mercury cathode with view trapping the sodium as sodium since any amalgam formed would diately be decomposed due to the presence of the end 5 calcium In view of these difficulties direct lytic production of bromine from bromide brines has far been considered On the other hand it been realised that direct duction of bromine from bromide brines has considerable economic both in te ras of capital investment and operational It the object of the present invention to provide a method for direct electrolytic production of bromine from bromide In accordance with the invention there is provided a method for the of bromine from a bromide comprising in the brine a cathode and a bromine sistant surrounding the anode by a at the bottom to form an anode containing brine in a nica ion with the surrounding difference between the anode compartment and the surrounding space such that the combined and vapour pressure in the former is lower than in the maintaining this pressure difference so that the brine within the anode compartment is constantly at a level above that of the brine outside the connecting the electrodes to a source of unidirectional allowing the unidirectional current to flow and tinuously withdrawing a bromine containing liquor from the anode The electrodes may be placed directly into the native In the pressure on the brine outside the anode vessel is atmospheric and the pressure prevailing within the vessel villi be subatmos Obviousl in t e course o th electrolysis H around cathode will not changed because of the direct the of the cathode and practically endless brine the pH within the anode does not rise appreciable and no formation Inside the anode compartment bromine forms continuously end to sink because of its specific being greater then tha the due to the that inside the anode compartment the liquid level is higher than the bulk of the sinking bromine remains within the compartment and is continuously In this undue bromine due to the sinking thereof It also to use a vessel the lysis and to place the anode within such vessel so that the space of the outside compartment constitute a eathode cosapartiaent In such a case the within the compartment will have to be replenished at the rate at which the liquor is the By a proper of the rate of any appreciable raise of pH and hypobroialte is again Such an is a simple empirical that can easily be carried out on the basis of the principles underlying tho present Where the brine also contains as is usually the chlorine will at first form at the and then the into is an excess ride a of chlorine and bromine the anode and mixture is withdrawn from the anode separation of the chlorine from each other is a simple operation known per the materials suitable for the anode graphite may be mentioned in The invention is of in the accompanying which is a sentation Of for the production of bromine in accordance with the present arrangement Illustrated comprises outer vessel end an inner vessel housing an anode and thus constituting the anode form of a perforated graphite plate located near the end of vessel 2 and is suspended from a conductor 4 leading the positive terminal of Within 1 and outside vessel 2 is located a cathode 5 suspended frost a tor 6 to the negative terminal of a pump 7 is designed to feed continuously fresh bromide brine into vessel 1 through duct A duct 9 leads the lower region of the anode 2 into a closed vessel 10 surrounded by a heating links the vessel 10 a A further duct 14 leads from vessel 10 to a pump whose delivery end is through a control valve 16 with a tainer collector duct 18 is linked through ducts 19 and 20 to vessels 2 and and serves for withdrawal of gaseous bromine or of chlorine and from these S leads to a 21 surrounded by cooling or insulating jacket 22 linked a duct 5 to a vacuum pump 4 During the brine is continuously delivered to vessel 1 by pump By the continuous action of pump 24 a reduced pressure is maintained within vessel so that the liquid level therein is higher than in vessel as shown in the While the electrolysis proceeds a liquor containing bromine and possibly also chlorine is continuously from vessel into vessel By the combined action of the heating 11 and the compressed air continuously delivered by compressor through duct a bromine or as t may is continuously expelled from the liquo vessel 10 through and sucked into trap At the any gaseous bromine and chlorine collecting in the upper part of vessel is drawn om through duct 19 and is equally sucked into trap Any chlorine arriving at trap 21 sucked out from by pump 00 th t substantially pure bromine collects in trap to constant flux the brine in vessels 1 and the pH does not rise o appreciable an no appreciable hypobromite due to the that the level of the liquid within 2 higher than in vessel 1 the bromine forming in the does praotioally not arrive at the and is withdrawn through duct invention is further Illustrated by the following Examples to which it is not 1 An apparatus as hereinbefore was having 2 a perforated graphite anode of 360 cm surface area and a Dead brine a bromide concentration of 4 to was delivered into vessel a ef a liquor was at the same rate from She current the anode was the voltage 6 volts and the temperature in 1 kept between 30 and After half hour a amount of β g of collected in trap above repeated the rate flow to er half an 7 g bromine lected in trap e experiment of 1 repeated tilth following conditione the anode 5 4 rate of liquid flow of After hal an hour 3 S had collected in trap 2 insufficientOCRQuality

Claims (1)

1. Method for the direct production of bromine from a bromide comprising placing in brine a cathode and a bromine resistant surrounding the anode by a vessel open at the bottom to form an anode compartment containing brine in the surrounding establishing a pressure difference betwee the anode compartment and the rounding spacG such that the combined gas and vapour pressure in the former is lower than in the maintaining pressure difference so that the brine within the anode is constantly at a level that o the brine side the connecting the electrodes to a source of unidirectional the unidirectional current to ow and continuously withdrawing a bromine containing liquor from the anode according to Claim cathode is placed directly the native Method according to Claim cathode and compartments are placed in a vesselto which the brine is constartly delivered at the same rate as tho bromine liquor is withdrawn from the anode Method for the direct production of bromine from a according to Claim as described insufficientOCRQuality