The invention relates to a method for recycling used lithium batteries containing the steps: (a) digestion of comminuted material (10), which contains comminuted components of electrodes of lithium batteries, using concentrated sulphuric acid (12) at a digestion temperature (T.sub.A) of at least 100 C., in particular at least 140 C., so that waste gas (14) and a digestion material (16) are produced, (b) discharge of the waste gas (14) and (c) wet chemical extraction of at least one metallic component of the digestion material (16).

The invention relates to a method for recycling used lithium batteries containing the steps: (a) digestion of comminuted material (10), which contains comminuted components of electrodes of lithium batteries, using concentrated sulphuric acid (12) at a digestion temperature (T.sub.A) of at least 100? C., in particular at least 140? C., so that waste gas (14) and a digestion material (16) are produced, (b) discharge of the waste gas (14) and (c) wet chemical extraction of at least one metallic component of the digestion material (16).

The invention relates to a method for recycling used lithium batteries containing the steps: (a) digestion of comminuted material (10), which contains comminuted components of electrodes of lithium batteries, using concentrated sulphuric acid (12) at a digestion temperature (T.sub.A) of at least 100? C., in particular at least 140? C., so that waste gas (14) and a digestion material (16) are produced, (b) discharge of the waste gas (14) and (c) wet chemical extraction of at least one metallic component of the digestion material (16).

A removal method of manganese in which manganese is removed by precipitating manganese selectively from sulfuric acid waste water containing aluminum, magnesium and manganese with inhibiting the precipitation of magnesium. The removal method of manganese from waste water in which manganese is removed by precipitating manganese selectively from the sulfuric acid waste water containing aluminum, magnesium and manganese with inhibiting the precipitation of magnesium, characterized in that said waste water is subjected to the following steps (1) and (2). (1) First, aluminum in said waste water is removed. (2) Subsequently, neutralizing agent is added into the wastewater after removing aluminum, then pH of the waste water is adjusted at 8.0 to 9.0, and oxygen gas is blown.