Papermaking

Lime in pulp production

The pulp industry uses lime in various stages of the production process:

• in chemical pulp production, sodium carbonate is treated with lime to regenerate the caustic soda;
• in the sulphate process, lime is used to produce a calcium bisulphate liquor capable of dissolving non-cellulose wood elements;
• lime is used as a bleaching agent for pulp, as well as a flocculating, neutralising and clarifying agent for residual water.
  

Lime to produce even whiter paper

Precipitated Calcium Carbonate, or PCC, is obtained by the carbonation of a milk-of-lime suspension. The papermaking sector uses large quantities of PCC as a filler or coating pigment to improve the optical properties of the paper.

A development in this field is the production of PCC on the premises of the papermaking plant, the so-called satellite-plant, by having the milk-of-lime reacting with CO2 available on site. The lime of Carmeuse, thanks to its whiteness (low iron and manganese content), is particularly suited for the production of a very bright PCC.