Info

Electrolyte

1,2 dimethoxyethane propylene carbonate lithium trifluoromethane sulphonate

Metal and plastics

The total weight of the cell is 16.2g. These cells are frequently configured as a 6V twin pack. The twin pack is a plastic shell.

The cell reactions for this system are:

2. 2. Recycling Process

During shredding, there may be some fumes formed if lithium metal remaining in the cells is ignited. These will be lithium oxide fumes. Some fine particulates (dust) may be carried in the ventilation stream. However, the components of the cells are nonvolatile solids or low-volatile liquids and are not expected to produce significant emissions during shredding.

The following reactions are likely to occur when the batteries are shredded and immersed in an alkaline water bath.

Un-reacted lithium metal will react with the water,

Anode reaction: Cathode reaction: Total cell reaction:

Mn^Ch + Li+ + e => (Li+)Mnm02 Li + Mnw02 => (Li+)Mnm02

2Li + 2H20 ==> 2LÍOH + H2 fw 2(6.94) 2(18.0) 2(23.94) 2.0 13.88 36.0 47.88 2.0

The amount of hydrogen produced will depend on the state of discharge of the battery. The hydrogen formed will be ignited by lithium burning on the surface of the treatment solution to form water.

Mn02 is insoluble in caustic solution and will precipitate.

The discharge product Li Mn02 will react in the alkaline bath to form lithium hydroxide and manganic oxyhydroxide:

2LiMn02 + 2H20 => 2LiOH + 2Mn(0H)0 2(93.87) 2(18.0) 2(23.94) 2(87.94)

187.74 36.0 47.88 175.88

The quantity of LiMn02 present will be governed by the degree of discharge of the battery.

Mn(0H)0 is insoluble in water and is stable to disproportionation.

The same products will be formed in the reaction bath whether the batteries are charged or discharged except for the relative proportions of Mn02 and Mn(0H)0. The Mn(0H)0 will only be formed from discharged batteries.

Propylene carbonate will hydrolyze in alkaline solution to propylene glycol and lithium carbonate:

C2H6C03 + 2LiOH => C3H6(OH)2 + Li,C03 102.09 2(23.94) 76.11 73.89

102.09 47.88 76.11 73.89

The propylene glycol is totally miscible with water. The lithium carbonate is insoluble and will precipitate with other lithium salts.

1,2-dimethoxyethane is soluble in water but is essentially non-reactive. As the concentration of the 1,2-dimethoxyethane builds up in the reaction tank solution, some may start to volatize. However, it is expected that any that does volatize will be ignited by the lithium burning on the surface. The combustion products will be carbon dioxide and water. The carbon dioxide will be absorbed in the caustic scrubber solution to form lithium carbonate which will precipitate with other lithium salts.

Lithium trifluoromethane sulphonate is a very stable and soluble salt. It will dissolve in the reaction tank solution until its solubility limit is reached, then precipitate with the other lithium salts.

2.3. Air Emissions

The shredding and treatment of Li/Mn02 batteries will result in minimal air emissions. Some Li20 may form from metallic lithium igniting on the surface of the reaction tank solution or in the shredder. Some Mn02 may be carried in the exhaust stream as a dust. Propylene carbonate is a high boiling liquid with a low vapour pressure. Any vapour that does form will be readily absorbed in the air emission scrubbers. 1,2-dimethoxythane is a moderately volatile liquid. Any vapour that does form will be captured in the scrubbers and returned to the reaction tank. Any that volatilizes from the reaction tank will be ignited along with the hydrogen given off from the lithium reaction.

It is expected that only minor quantities of sub-micron sized fume will pass through the air emission scrubbers. No gases are expected.

2.4. Biological Effects

The components and reaction by-products of Li/Mn02 batteries have generally low toxicities.

• Lithium metal is a hazard because of its violent reaction with water. No toxicological data is available. Exposure can cause severe burn.

• Lithium oxide (Li20) is corrosive. Exposure or inhalation causes severe irritation or burns. No toxicological data is available.

• Lithium triofluoromethane sulphonate has low toxicity but may cause mild skin or upper respiratory irritation.

• Manganese dioxide and manganic oxyhydroxide have low toxicity but may cause respiratory irritation.

• 1,2-dimethoxythane has low toxicity but may cause dizziness, difficult breathing or nausea if handled. Skin contact may cause irritation.

• Propylene carbonate is non-toxic but may cause irritation with prolonged contact.

• Propylene glycol is non-toxic and has been used to replace glycerol in food products and cosmetics.

Normal safe-handling procedures should prevent any risk to workers dealing with the solids or solutions. Air emissions will be controlled through the ventilation system. No environmental risks are expected.

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