Claims:We Claim:
1) A process for reducing iodide concentration in brine, comprising:
introducing untreated brine containing impure iodide over a specific concentration in a circulation tank (T1);
mixing the untreated brine with ozone of measured concentration;
introducing the untreated brine mixed with the ozone to a fluidized bed reactor (F1) for providing an effective contact surface for reaction there between, thereby treating the untreated brine;
re-introducing overflow brine from the fluidized bed reactor (F1) into the circulation tank (T1) for treatment; and
simultaneously emitting the treated brine with reduced iodide concentration from the circulation tank (T1).

2) The process as claimed in claim 1, wherein the specific concentration of the impure iodide in the untreated brine is between 100-400ppb.

3) The process as claimed in claim 1, wherein the measured concentration of ozone is in range of 1gram of ozone for reduction of 3-10 grams of iodide.

4) The process as claimed in claim 1, wherein the reduced iodide concentration in the treated brine is between 20-100ppb.
5) The system for reducing iodide concentration in brine, comprising:
a circulation tank (T1) configured to receive untreated brine containing impure iodide over a specific concentration;
a circulation pump (P1) connected to the circulation tank (T1) and configured to keep the untreated brine in circulation; and
a fluidized bed reactor (F1) configured to receive the untreated brine mixed along with measured concentration of ozone and provide effective contact surface of reaction to obtain treated brine;
wherein overflow brine from the fluidized bed reactor (F1) is re-introduced into the circulation tank (T1), and
wherein the treated brine with reduced iodide concentration is let out from the circulation tank (T1).

6) The system as claimed in claim 5, wherein the specific concentration of the impure iodide in the untreated brine is between 100-400ppb.

7) The system as claimed in claim 5, wherein the measured concentration of ozone is in range of 1gram of ozone for reduction of 3-10 grams of iodide.

8) The system as claimed in claim 5, wherein the reduced iodide concentration in the treated brine is between 20-100ppb.

9) The system as claimed in claim 5, wherein the fluidized bed reactor (F1) is constructed of PVC or stainless steel.

10) The system as claimed in claim 5, wherein the fluidized bed reactor (F1) comprising fluidized bed media is glass beads of size ranging from 0.5-5mm.

11) The system as claimed in claim 5, wherein the fluidized bed reactor (F1) has a bed height varying from 1-2meters.

12) The system as claimed in claim 5, further comprising a venturi fixed at delivery end of the circulating pump (P1) for effective mixing and reaction of the ozone with the untreated brine.
, Description:FIELD OF INVENTION

[01] The subject matter described herein, in general, relates to a process and system for reduction of trace concentration of iodine in brine, and, more particularly to the reduced concentration of iodide to the extent of 20-100ppb.

BACKGROUND OF INVENTION

[02] In a Chloralkali industry, products such as Caustic Soda, Chlorine, Hydrogen, Hydrochloric acid & Sodium hypochlorite are produced through membrane electrolysis. There are various technologies through which these products are produced. Membrane technology is the latest one which is environment-friendly, mercury free and energy efficient.
[03] In the membrane chloralkali industry one of the major raw material is the Industrial grade salt (Sodium Chloride). Salt is dissolved in water or depleted brine and the impurities such as calcium, magnesium and other insoluble present in the salt are separated using chemicals such as sodium carbonate, sodium hydroxide. Impurities such as Calcium, and magnesium salts are precipitated.
[04] The brine with insoluble impurities is allowed to settle in a clarifier wherein the clarified brine is obtained leaving behind all the insoluble precipitates settled at the bottom of the clarifier as sludge. The clarified brine from the clarifier has some insoluble impurities in the form of suspended solids in ppm levels. The suspended solids are separated through media filters and ultrafilters to obtain brine free from all suspended solids. This is called as polished brine. Polished brine is passed through the Ion-exchange columns for removal of trace calcium and magnesium impurities to less 20 – 30 ppb which is called the purified brine.
[05] The purified brine has dissolved iodide concentration ranging between 100 – 400 ppb depending upon the source of the salt procured. Technology suppliers recommend an ideal concentration of Iodide at < 100 ppb in the pure brine for efficient operation of the electrolysers. High content of iodide is generally found in the Industrial grade salt (Sodium Chloride) procured for solar salt fields which does not have washery or any additional purification methods. In these fields, salt is just scrapped from the crystallizer, heaped and washed with water to reduce magnesium. The removal of iodine from such purified brine is imperative for efficient membrane chloralkali process.
[06] Thus, in the background of foregoing limitations there exists a need for an efficient, yet a simple method capable of removing trace iodine impurities in the chloralkali brine for a chloralkali industry.

OBJECT OF THE INVENTION
[07] The primary object of the present disclosure is to provide an efficient process and system for removal of trace iodine impurities in the chloralkali brine.
[08] Another object of this disclosure is to provide a cost-effective, easy to follow process and system for reducing trace iodide impurities to the tune of less than 400ppb in the chloralkali brine.
[09] Yet another object of the disclosure is to provide an effective electrolysis process that eliminates the precipitation of iodide on membranes thereby ensuring optimized voltage and current flow.
[010] Yet other object of the present disclosure is to provide electrolyzers capable of operating at higher current densities for reasons of lower iodide concentration, which reduced the foot print and capital cost.
[011] In yet another embodiment, the disclosure provides a simple, albeit a sophisticated process and system that can reduce overall operational cost by way of using salt with higher iodide concentration for production of chloroalkali products.
[012] In yet another embodiment of present disclosure, the use of manually washed salt that is easily available locally leads to sustainability of entire operation.
[013] One other embodiment of present disclosure provides an economical process that uses manually washed salt which is cheaper than salt obtained from washery.
[014] Yet another embodiment of present disclosure provides reduced trace concentration of iodide in both chloroalkali brine (NaCl) or Potassium Chloride brine.
[015] These and other objects will become apparent from the ensuing description of the present invention.

SUMMARY OF THE INVENTION
[016] The present invention is directed to a process for reducing iodide concentration in brine, comprising the following steps. First step involves introducing untreated brine containing impure iodide over a specific concentration in a circulation tank; mixing the untreated brine with ozone of measured concentration; introducing the untreated brine mixed with the ozone to a fluidized bed reactor for providing an effective contact surface for reaction there between, thereby treating the untreated brine; re-introducing overflow brine from the fluidized bed reactor into the circulation tank for treatment; and simultaneously emitting the treated brine with reduced iodide concentration from the circulation tank.
[017] In one aspect of present disclosure, the system for reducing iodide concentration in brine is disclosed. The system comprises of a circulation tank configured to receive untreated brine containing impure iodide over a specific concentration; a circulation pump connected to the circulation tank and configured to keep the untreated brine in circulation; and a fluidized bed reactor configured to receive the untreated brine mixed along with measured concentration of ozone and provide effective contact surface of reaction to obtain treated brine; wherein overflow brine from the fluidized bed reactor is re-introduced into the circulation tank, and wherein the treated brine with reduced iodide concentration is let out from the circulation tank.
[018] These and other aspects, features and advantages of the present invention will be described or become apparent from the following detailed description of preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS
[019] Fig. 1 depicts system for treating brine laced with impure iodide concentration, in accordance with one preferred embodiment of present disclosure.
[020] Fig. 2 is a flow chart of process for reducing traces of iodide concentration, in accordance with one preferred embodiment of present disclosure.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[021] Before the present process and system of removing trace iodide impurities from chloralkali brine is described, it is to be understood that this disclosure is not limited to the particular system and process, as described, since it may vary within the specification indicated. It is also to be understood that the terminology used in the description is for describing the particular versions or embodiments only and is not intended to limit the scope of the present invention, which will be limited only by the appended claims. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. The disclosed embodiments are merely exemplary methods of the invention, which may be embodied in various forms.
[022] Broadly, the present disclosure provides an efficient process for removal of trace iodide impurities to less than 400ppb in the chloralkali brine having approx between 300-330 gpl of sodium chloride. The process makes an efficient use of fluidized bed reactor for achieving the desired output. In general, the removal of iodide at low concentration (< 400 ppb) becomes very difficult and therefore a suitable method has to be evolved for its reduction.
[023] In the membrane Chloralkali process, the pure brine which is the feedstock comprises of 100-400 ppb of iodide in the dissolved form, which is detrimental to the electrolysis process. During the process of electrolysis the iodide tends to precipitate on to the membranes causing decrease in current efficiency and increase in voltage.
[024] In accordance with one preferred embodiment of present disclosure, the process developed for removal of traces of iodide is by making use of Ozone. Ozone, as well understood, is a highly oxidizing agent. It oxidizes the iodide and is purged out of the brine. Accordingly, the process so designed comprises of a fluidized bed reactor wherein the brine is circulated and ozone is passed along with the brine for reaction with iodide in the brine.
[025] A reduction of 75 – 90 % of the iodide has been achieved using this process. The brine with the reduced iodide concentration can be suitably used for the electrolysis process for production of caustic and chlorine. As per the technology suppliers the iodide concentration should be < 100 ppb. This process of iodide removal can be applied to any brine either sodium chloride or potassium chloride brine.
[026] One working embodiment of present disclosure comprises of a process set up 100 that broadly comprises of a circulation tank (T1), a circulation pump (P1), and a fluidized bed reactor (F1). Specifically, the brine with the impurity iodide (100 – 400 ppb) enters from the top of circulation tank (T1). A circulation pump (P1) is connected to the tank (T1) which keeps the brine in circulation from T1 to a fluidized bed reactor (F1). The over flow from the fluidized column is put back into the circulation tank (T1). Ozone (O1) of measured concentration and flow is sucked through a venturi (V1) fixed at the delivery end of the pump (P1). The concentration of ozone depends on the quality & quantity of the brine processed. The ozone sucked will mix uniformly with the brine and enters the fluidized bed reactor (F1) where it is provided with an effective contact surface for reaction. Due to the fluidized bed, the efficiency of iodide reaction with ozone is much higher and the overflow brine from the fluidized bed reaction is put back into the circulation tank (T1). The fresh brine (I) entering the tank gets treated and the brine with reduced iodide is taken out (O) continuously.
[027] In accordance with one exemplary embodiment, the fluidized bed reactor (F1) is made of PVC/SS or any plastic material. Further, the fluidized bed media is of glass beads (G1) size ranging approximately from 0.5 to 5 mm and the bed height varied from 1.0 meters to 2.0 meters approx. The specific consumption of ozone ranges from about 3 to 10 gram of iodide reduction per gram of ozone. Further, the brine with a temperature of around 70 degrees can be processed through this process. Furthermore, uniform quantity of the brine is taken out from the circulation thus establishing a continuous process of iodide reduction and continuous production of pure brine with traces of iodide. The reduction efficiency obtained is approx. in the range of 75 % - 90 %.
[028] During the start up of the process, the brine in the circulation tank (T1) is circulated through the fluidized bed reactor (F1) to get an iodide concentration of 20 – 100 ppb and then fresh brine is introduced along with an equal quantity of it being let out of the tank, thereby establishing the continuous flow.
[029] One preferred embodiment of present disclosure, as shown in Fig.2, presents a flow chart of above discussed process. Accordingly, at first the pure brine containing around 300-320 gpl of NaCl is introduced in circulation tank, pumped by a circulation pump. Thereafter, ozone is introduced to the pure brine and the combination is made to enter the fluidized bed reactor, which re-channelizes the combination to the circulation tank, from where the treated brine with low iodide concentration is let out.
[030] In accordance with one working embodiment, Table 1 depicts the experimental results for obtaining reduction of trace of iodide in brine within a fluidized bed of given particulars. For example, the bed height is maintained at 1 meters-1.5 meters. Various other particulars being brine flow (LPH), iodine concentration in pure brine (ppb), iodine concentration after treatment (ppb), ozone introduced (gm/hr), iodine removed per gm of ozone (ppb) and % reduction of iodide obtained.

Table 1
[031] The above result clearly depicts reduced iodide concentration obtained after treatment using process flow of present disclosure.
[032] The disclosure herein explicitly states that the numbers and values mentioned above are approximate values. Hence, there can be slight change in the values at actual to conceive the proposed solution. The foregoing description is a specific embodiment of the present disclosure. It should be appreciated that this embodiment is described for purpose of illustration only, and that those skilled in the art may practice numerous alterations and modifications without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.