A method of producing lithium hydroxide using a variety of aqueous solutions as a source liquid. The method includes: providing a lithium ion extraction liquid, including a first mixing of an aqueous solution containing lithium and at least one kind of an element other than lithium and a base in a reaction tank, with a pH regulated to 6 or more and 10 or less, a second mixing of the aqueous solution and the base, with a pH regulated to 12 or more, and removal of a hydroxide of the element other than lithium formed through the first and second mixing; recovering only lithium ion from the lithium ion extraction liquid to a recovery liquid with an electrochemical device including a Li-selectively permeable membrane; and performing the regulation of pH by returning the lithium ion extraction liquid after recovering lithium ion with the electrochemical device to the reaction tank.

A method of producing lithium hydroxide using a variety of aqueous solutions as a source liquid. The method includes: providing a lithium ion extraction liquid, including a first mixing of an aqueous solution containing lithium and at least one kind of an element other than lithium and a base in a reaction tank, with a pH regulated to 6 or more and 10 or less, a second mixing of the aqueous solution and the base, with a pH regulated to 12 or more, and removal of a hydroxide of the element other than lithium formed through the first and second mixing; recovering only lithium ion from the lithium ion extraction liquid to a recovery liquid with an electrochemical device including a Li-selectively permeable membrane; and performing the regulation of pH by returning the lithium ion extraction liquid after recovering lithium ion with the electrochemical device to the reaction tank.

The present disclosure relates to a method for recovery of valuable metals and a zeolite-containing material from a waste cathode material reaction vessel, in which valuable metals and a zeolite-containing material are recovered from a waste cathode material reaction vessel being discarded, and recycled as resources, thus reducing waste from the waste cathode material reaction vessel.

A method for concentrating an aqueous caustic alkali produced by a membrane cell process by using a single or multiple effect evaporator system in which the vapor flows in a counter direction to the aqueous caustic alkali flow and the heat recovered from the catholyte circulation line is used as part of the concentration process. In one embodiment, a catholyte heat recovery heat exchanger and flash evaporation chamber are located after the last effect of a multiple effect evaporator system. In another embodiment, the catholyte heat recovery heat exchanger and flash evaporation chamber are located prior to the single or multiple effect evaporator system. In yet another embodiment, the catholyte heat recovery process is used in conjunction with additional heat exchanger processes to further concentrate the final product as desired.

A method for concentrating an aqueous caustic alkali produced by a membrane cell process by using a single or multiple effect evaporator system in which the vapor flows in a counter direction to the aqueous caustic alkali flow and the heat recovered from the catholyte circulation line is used as part of the concentration process. In one embodiment, a catholyte heat recovery heat exchanger and flash evaporation chamber are located after the last effect of a multiple effect evaporator system. In another embodiment, the catholyte heat recovery heat exchanger and flash evaporation chamber are located prior to the single or multiple effect evaporator system. In yet another embodiment, the catholyte heat recovery process is used in conjunction with additional heat exchanger processes to further concentrate the final product as desired.

A method of concentrating and/or producing lithium hydroxide in an evaporator entails feeding a stream comprising lithium, hydroxide and carbonate to the evaporator. In the evaporator, the feed is concentrated to form lithium hydroxide and lithium carbonate crystals. Further, the method entails reducing the tendency of lithium carbonate to scale the evaporator by increasing the concentration of lithium carbonate crystals in the evaporator by: (1) clarifying at least a portion of the concentrate in the evaporator to form a clarified solution; and (2) discharging the clarified solution as a clarified solution stream from the evaporator.

A method for concentrating an aqueous caustic alkali produced by a membrane cell process by using a single or multiple effect evaporator system in which the vapor flows in a counter direction to the aqueous caustic alkali flow and the heat recovered from the catholyte circulation line is used as part of the concentration process. In one embodiment, a catholyte heat recovery heat exchanger and flash evaporation chamber are located after the last effect of a multiple effect evaporator system. In another embodiment, the catholyte heat recovery heat exchanger and flash evaporation chamber are located prior to the single or multiple effect evaporator system. In yet another embodiment, the catholyte heat recovery process is used in conjunction with additional heat exchanger processes to further concentrate the final product as desired.

A method for concentrating an aqueous caustic alkali produced by a membrane cell process by using a single or multiple effect evaporator system in which the vapor flows in a counter direction to the aqueous caustic alkali flow and the heat recovered from the catholyte circulation line is used as part of the concentration process. In one embodiment, a catholyte heat recovery heat exchanger and flash evaporation chamber are located after the last effect of a multiple effect evaporator system. In another embodiment, the catholyte heat recovery heat exchanger and flash evaporation chamber are located prior to the single or multiple effect evaporator system. In yet another embodiment, the catholyte heat recovery process is used in conjunction with additional heat exchanger processes to further concentrate the final product as desired.

The present invention discloses a method for quickly extracting lithium carbonate from saline lake water and a system for the same. The method comprises: first quick-freezing the saline lake water to obtain lithium-rich brine, then evaporating under reduced pressure to enable lithium carbonate to be rapidly precipitated out. The method has advantages of short process flow and less labor consumption, thereby enabling continuous automatic operation, high energy utilization and environment-friendly. Further, the crystallization rate is several times faster than that of the salt-pan process and the grade of lithium carbonate salt mine obtained can reach 95% or more, therefore the method of the present invention is particularly suitable for industrial production in the remote saline lake region. The system comprises a reduced-pressure evaporation crystallizer, a vacuum-pumping apparatus, a brine preheating apparatus and a brine cooling apparatus, which concentrates the brine by quick-evaporation of the water, promotes lithium carbonate to form non-uniform nucleus, and improves the crystallization efficiency.

Concentrated aqueous sodium hydroxide solution comprising: at least 25% by weight of NaOH, sodium chloride (NaCl) and/or sodium sulfate (Na.sub.2SO.sub.4), and one soluble impurity from a sodium carbonate or bicarbonate ore deposit, said soluble impurity being selected among: As, Ba, B, Ca, Co, K, Li, Mg, Mo, P, Pb, Se, Si, Sr, Te, Tl, Ti, V, W, and the soluble impurity being in specific concentrations ranges. And process for producing such concentrated aqueous sodium hydroxide solution by treating a purge stream comprising sodium carbonate or bicarbonate.