Micronized Sodium Sulfate (finely ground sodium sulfate) is used in the pulp and paper industry for various purposes, primarily in the pulping and papermaking processes. Its main applications in this industry include:
Pulping
Sodium sulfate can be used as a cooking liquor additive in the pulping process, particularly in kraft pulping. It helps control the alkalinity and pH levels in the pulping liquor, which is important for efficiently breaking down wood chips into pulp. Sodium sulfate can also aid in the removal of lignin and other impurities from the wood fibres.
Kraft Pulping
In kraft pulping, sodium sulfate is added to the pulping liquor to maintain a stable alkaline environment (high pH) and promote the separation of lignin from cellulose fibres. This process is essential for producing strong and high-quality pulp.
Deinking
In the recycling of paper and cardboard products, sodium sulfate may be used in the deinking process to aid in the removal of ink and other contaminants from the recycled fibres. It helps in improving the quality of recycled paper.
Paper Sizing
Sodium sulfate can be used as a filler or as part of the sizing formulation to improve the paper’s strength and surface characteristics. It can also act as a pH buffer in sizing solutions.
Pigment Dispersant
In the paper coating process, sodium sulfate may be used as a dispersant for pigments and other additives, ensuring even distribution and adherence of coatings to the paper surface.
Cost-effective Additive
Sodium sulfate is often added to paper formulations as a cost-effective filler or diluent.