Green liquor is the dissolved smelt of
sodium carbonate,
sodium sulfide
Sodium sulfide is a chemical compound with the formula Na2 S, or more commonly its hydrate Na2S·9 H2O. Both the anhydrous and the hydrated salts in pure crystalline form are colorless solids, although technical grades of sodium sulfide are gener ...
and other compounds from the
recovery boiler Recovery boiler is the part of kraft process of pulping where chemicals for white liquor are recovered and reformed from black liquor, which contains lignin from previously processed wood. The black liquor is burned, generating heat, which is usual ...
in the
kraft process
The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper. The kraft process involves treatment of wood chip ...
. The liquor's eponymous green colour arises from the presence of colloidal iron sulfide.
The green liquor is usually reacted with
lime
Lime commonly refers to:
* Lime (fruit), a green citrus fruit
* Lime (material), inorganic materials containing calcium, usually calcium oxide or calcium hydroxide
* Lime (color), a color between yellow and green
Lime may also refer to:
Botany
...
(CaO) in the ''causticizing stage'' to regenerate
white liquor. Alternatively, green liquor can be used prior to white liquor to extract some hemicellulose.
References
Papermaking
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