The invention concerns non-ferrous metallurgy, in particular the composition of an electrolyte for electrically obtaining aluminum by the electrolysis of fluoride melts. The electrolyte proposed contains, in % by weight: sodium fluoride 26-43, potassium fluoride up to 12, lithium fluoride up to 5, calcium fluoride 2-6, alumina 2-6, aluminum fluoride and admixtures—the remainder. The technical result is to increase the solubility of alumina in the electrolyte at a temperature of 830-930° C. In the electrolyte being applied for, the carbon and inert electrode materials are not destroyed, and the use of special methods to purify the aluminum of melt components is not required.

The invention concerns non-ferrous metallurgy, in particular the composition of an electrolyte for electrically obtaining aluminum by the electrolysis of fluoride melts. The electrolyte proposed contains, in % by weight: sodium fluoride 26-43, potassium fluoride up to 12, lithium fluoride up to 5, calcium fluoride 2-6, alumina 2-6, aluminum fluoride and admixtures—the remainder. The technical result is to increase the solubility of alumina in the electrolyte at a temperature of 830-930° C. In the electrolyte being applied for, the carbon and inert electrode materials are not destroyed, and the use of special methods to purify the aluminum of melt components is not required.

A method for transforming a crystal form of an electrolyte containing lithium for aluminum electrolysis includes the following steps: S1, pulverizing the electrolyte containing lithium; S2, uniformly mixing an additive with the electrolyte powder to obtain a mixture, wherein the additive is one or more selected from the group consisting of an oxide of an alkali metal other than lithium, an oxo acid salt of an alkali metal other than lithium, and a halide of an alkali metal other than lithium; a molar ratio of a sum of alkali metal fluoride contained in the electrolyte, alkali metal fluoride directly added from the additive, and alkali metal fluoride to which the additive is converted under the high-temperature calcination condition in the mixture to aluminum fluoride is greater than 3; S3, calcining the mixture at a high temperature.

A method for transforming a crystal form of an electrolyte containing lithium for aluminum electrolysis includes the following steps: S1, pulverizing the electrolyte containing lithium; S2, uniformly mixing an additive with the electrolyte powder to obtain a mixture, wherein the additive is one or more selected from the group consisting of an oxide of an alkali metal other than lithium, an oxo acid salt of an alkali metal other than lithium, and a halide of an alkali metal other than lithium; a molar ratio of a sum of alkali metal fluoride contained in the electrolyte, alkali metal fluoride directly added from the additive, and alkali metal fluoride to which the additive is converted under the high-temperature calcination condition in the mixture to aluminum fluoride is greater than 3; S3, calcining the mixture at a high temperature.

Disclosed is a method of regenerating a nitric and hydrofluoric acid bath contained in a machining vessel, the method including, when the etching bath is spent, performing steps of: transferring a portion of the spent etching bath, referred to as the spent solution, from the machining vessel into a reactor; adding NaF and NaNO.sub.3 to the spent solution, to form HF, HNO.sub.3, and Na.sub.2TiF.sub.6; separating the resulting precipitate from the supernatant; transferring the supernatant, which is a regenerated solution, into a tank; measuring the concentrations of HF, of HNO.sub.3, and of dissolved titanium in the tank and in the machining vessel; and determining the volume of regenerated solution that can be added to the spent etching bath to obtain a regenerated bath in which the concentrations of HF, of HNO.sub.3, and of dissolved titanium lie in acceptable concentration ranges, and transferring the regenerated solution into the machining vessel.

The solid electrolyte material of the present disclosure comprises Li, M, I, and X. M is at least one element selected from the group consisting of Al, Ga, and In. X is at least one element selected from the group consisting of F, O, and S. The battery of the present disclosure comprises a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode. At least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte layer contains the solid electrolyte material of the present disclosure.

The solid electrolyte material of the present disclosure comprises Li, M, I, and X. M is at least one element selected from the group consisting of Al, Ga, and In. X is at least one element selected from the group consisting of F, O, and S. The battery of the present disclosure comprises a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode. At least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte layer contains the solid electrolyte material of the present disclosure.

Disclosed is a method for efficiently removing fluorine from a spent lithium battery. The method comprises: mixing aluminum and a sodium hydroxide solution for reaction to obtain a sodium metaaluminate solution; introducing sulfuric acid into the sodium metaaluminate solution, and stirring to react at a certain temperature to obtain a fluorine removal agent; adding a sodium fluoroaluminate seed crystal and the fluorine removal agent into an impurity-removed battery powder leaching solution, introducing a sodium carbonate solution at the same time, performing reaction at a certain temperature, controlling the pH value of a reaction endpoint, and performing solid-liquid separation after the reaction is finished to obtain a fluorine-removed liquid and filter residues; and adding the sodium hydroxide solution into the filter residues for reaction, and performing solid-liquid separation to obtain a filtrate containing fluorine and aluminum, and insoluble residues. According to the present invention, fluorine removal is induced by adding the sodium fluoroaluminate seed crystal; and during fluorine removal, the seed crystal sodium fluoroaluminate is firstly added into the battery leaching solution, and by means of induction of the seed crystal, combination of fluorine and aluminum in the solution can be accelerated to generate sodium hexafluoroaluminate, the reaction time is shortened, the fluorine removal efficiency is improved, and fluorine in the solution can be removed to be lower than 20 mg/L, thereby achieving the purpose of deep fluorine removal.

The disclosure provides a method for preparing an electrolyte and an electrolyte replenishment system during an electrolytic process. The method includes the following steps: Step A: placing aluminum in a reactor, vacuumizing the reactor and feeding an inert gas, heating the reactor to 700-850 degrees centigrade, and adding one or more of potassium fluozirconate, potassium fluoborate, sodium hexafluorozirconate and sodium fluoroborate; and Step B: stirring the reactants for 4-6 hours and extracting the upper molten liquid to obtain an electrolyte replenishment system during an aluminum electrolysis process. The disclosure has the following beneficial effects: when used in the aluminum electrolysis industry, the electrolyte system provided herein can be directly used as an aluminum electrolyte or a replenishment system in an electrolyte without changing existing electrolysis technology to significantly reduce an electrolysis temperature during an aluminum electrolysis process.

The disclosure provides a method for preparing an electrolyte and an electrolyte replenishment system during an electrolytic process. The method includes the following steps: Step A: placing aluminum in a reactor, vacuumizing the reactor and feeding an inert gas, heating the reactor to 700-850 degrees centigrade, and adding one or more of potassium fluozirconate, potassium fluoborate, sodium hexafluorozirconate and sodium fluoroborate; and Step B: stirring the reactants for 4-6 hours and extracting the upper molten liquid to obtain an electrolyte replenishment system during an aluminum electrolysis process. The disclosure has the following beneficial effects: when used in the aluminum electrolysis industry, the electrolyte system provided herein can be directly used as an aluminum electrolyte or a replenishment system in an electrolyte without changing existing electrolysis technology to significantly reduce an electrolysis temperature during an aluminum electrolysis process.