Abstract: A valuable metal recovery method includes: recovering a battery slag from lithium ion battery waste; adding an acid to the battery slag; adding a sulfur compound the leachate; filtering the first processed product to obtain a first processed filtrate; adding a sulfur compound to the first processed filtrate; filtering the second processed product to obtain a second processed filtrate; adding calcium hydroxide to the second processed filtrate; filtering the third processed product to obtain a third processed filtrate; adding sodium carbonate to the third processed filtrate; filtering the processed product; heating the fourth processed filtrate; blowing carbon dioxide or adding a carbonate; and filtering the processed product, wherein a pH of the second processed product is higher than a pH of the first processed product, and a pH of the third processed product is higher than the pH of the second processed product.

Abstract: A Li recovery method includes: an acid leaching step of adding an acid to a battery slag to produce a leachate; a first addition step of adding a Ca content to the leachate to produce a first processed product; a post-first-addition filtration step of filtering the first processed product to be separated into a first processing filtrate and a first processing residue; a second addition step of adding sodium carbonate to the first processing filtrate to produce a second processed product; a post-second-addition filtration step of filtering the second processed product to be separated into a second processing filtrate and a second processing residue; heating the second processing filtrate; blowing carbon dioxide into the heated second processing filtrate to produce a third processed product; and a post-carbonation filtration step of filtering the third processed product to be separated into a third processing filtrate and a third processing residue.

Abstract: A polarizing membrane according to an embodiment of the present invention includes a polyvinyl alcohol-based resin membrane containing a dichromatic substance. The polyvinyl alcohol-based resin membrane has an Nz coefficient of 1.10 or more and 1.50 or less.

Abstract: The invention relates to a method for manufacturing an optical film. The method includes an unwinding step, a cleaning step and an application step. In the unwinding step, a long-band shaped flexible base having a first principal surface and a second principal surface is unwound from a continuous roll, and the base is continuously fed to a downstream side. In the cleaning step, a cleaning liquid is supplied between the second principal surface of the base and a cleaning roll, and the cleaning liquid is applied and spread over the base by the cleaning roll to clean the second principal surface of the base. Thereafter, in the application step, a resin solution is applied onto the first principal surface of the base and then the resin solution is dried.

Abstract: A piezoelectric device has a plate-shaped substrate, a first frame defining a first concave portion at one surface of the substrate, a second frame defining a second concave portion at the other surface of the substrate, a first electrode member provided at one surface of the substrate, a second electrode member provided at the other surface of the substrate, a piezoelectric unit in which a first electrode section of the piezoelectric vibration plate is fixed to the first electrode member by a conductive binder, a cover sealing the first concave portion, and a temperature detection unit in which a second electrode section of the thermistor element is fixed to the second electrode member by a conductive joining material.

Abstract: A polarizing membrane according to an embodiment of the present invention includes a polyvinyl alcohol-based resin membrane containing a dichromatic substance. The polyvinyl alcohol-based resin membrane has an Nz coefficient of 1.10 or more and 1.50 or less.

Abstract: A piezoelectric device has a plate-shaped substrate, a first frame defining a first concave portion at one surface of the substrate, a second frame defining a second concave portion at the other surface of the substrate, a first electrode member provided at one surface of the substrate, a second electrode member provided at the other surface of the substrate, a piezoelectric unit in which a first electrode section of the piezoelectric vibration plate is fixed to the first electrode member by a conductive binder, a cover sealing the first concave portion, and a temperature detection unit in which a second electrode section of the thermistor element is fixed to the second electrode member by a conductive joining material.