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: The present invention provides an apparatus for electrically and hydraulically driving a hydraulic cylinder, including a hydraulic pump rotatable in opposite directions, an electric motor for driving the hydraulic pump, a reservoir tank containing hydraulic fluid therein, and a servo-valve. The hydraulic cylinder makes fluid-communication at a head-sided hydraulic chamber with a first port of the hydraulic pump, and makes fluid-communication at a rod-sided hydraulic chamber with a second port of the hydraulic pump. The servo-valve allows ones of the head-sided hydraulic chamber and the rod-sided hydraulic chamber to make fluid-communication to the reservoir tank in accordance with a direction in which the hydraulic pump rotates, and varies a degree at which one of the head-sided hydraulic chamber and the rod-sided hydraulic chamber makes fluid-communication with the reservoir tank, to a designated degree.