Provided is a method for co-producing iodine and salt by use of underground brine containing iodine salt and sodium chloride. The method is a method to produce iodine and salt in parallel including a series of steps including: an iodine acquisition step; a collecting step for obtaining concentrated brine by simultaneously concentrating iodine salt and sodium chloride by using an electrodialysis device; and a roasting step for obtaining salt. The present invention encompasses various aspects in terms of the order of performing the iodine acquisition step, the collecting step, and the roasting step, which are included in the series of steps.

The present invention provides a method for reducing the concentration of aluminum and nickel cations in a brine comprising aluminum and nickel cations. The treated brine can be used as a feedstock to membrane cell chlor-alkali process.

The present invention provides a method for reducing the concentration of aluminum and nickel cations in a brine comprising aluminum and nickel cations. The treated brine can be used as a feedstock to membrane cell chlor-alkali process.

A process for the preparation of purified potassium chloride comprises the at least partial removal of one or more class 1 heavy metal impurity (lead, arsenic, cadmium and/or mercury) from potassium chloride process liquor by an ion exchange step. The process uses an ion exchange resin and achieves high levels of purity and is compatible with high flow rates. A recrystallisation step (e.g. a cooling crystallization step) may be employed subsequent to the ion exchange step.

The present invention provides a process for separating iodine from a NaCl brine, comprising the following steps: (a) providing said NaCl brine containing iodide, (b) adjusting the pH of said NaCl brine to be no greater than 1.5, (c) adding oxidizing agent, such as chlorine containing oxidizing agent, to said NaCl brine resulting from step (b) to obtain an oxidation-reduction potential in said NaCl brine of from 560 mV to 925 mV, the combination of said pH of no greater than 1.5 and oxidation-reduction potential of 560 mV to 925 mV resulting in the formation of an iodine-chlorine anionic complex, and (d) contacting nonionic adsorption resin and said NaCl brine from step (c) one with the other to adsorb said iodine from this brine, to obtain as a result thereof NaCl brine wherein the iodine content therein is preferably no greater than 100 ppbw, more preferably no greater than 10 ppbw.

The present invention provides a method for reducing the concentration of aluminum and nickel cations in a brine comprising aluminum and nickel cations. The treated brine can be used as a feedstock to membrane cell chlor-alkali process.

The present invention provides a method for reducing the concentration of aluminum and nickel cations in a brine comprising aluminum and nickel cations. The treated brine can be used as a feedstock to membrane cell chlor-alkali process.

Methods are disclosed for removing alkali metal iodide from concentrated aqueous alkali metal chloride solutions using ion retardation resins. The methods are suitable for solutions comprising substantially more than 1 ppm iodide and greater than 100 g/l alkali metal chloride and can remove the iodide to levels below 1 ppm. To effect removal, the pH of the solution is adjusted to be less than about 10 and is then flowed through a separation bed comprising the resin in a series of loading and elution cycles. The method is particularly useful for removing iodide impurity from the concentrated feed brine used in chloralkali electrolysis.

The present invention provides a process for separating iodine from a NaCl brine, comprising the following steps: (a) providing said NaCl brine containing iodide, (b) adjusting the pH of said NaCl brine to be no greater than 1.5, (c) adding oxidizing agent, such as chlorine containing oxidizing agent, to said NaCl brine resulting from step (b) to obtain an oxidation-reduction potential in said NaCl brine of from 560 mV to 925 mV, the combination of said pH of no greater than 1.5 and oxidation-reduction potential of 560 mV to 925 mV resulting in the formation of an iodine-chlorine anionic complex, and (d) contacting nonionic adsorption resin and said NaCl brine from step (c) one with the other to adsorb said iodine from this brine, to obtain as a result thereof NaCl brine wherein the iodine content therein is preferably no greater than 100 ppbw, more preferably no greater than 10 ppbw.

A process for the preparation of purified potassium chloride comprises the at least partial removal of one or more class 1 heavy metal impurity (lead, arsenic, cadmium and/or mercury) from potassium chloride process liquor by an ion exchange step. The process uses an ion exchange resin and achieves high levels of purity and is compatible with high flow rates. A recrystallisation step (e.g. a cooling crystallization step) may be employed subsequent to the ion exchange step.