Lignosulfonates, derived from the pulping process of bamboo and wood, are versatile water-soluble polymers known for their exceptional dispersant properties. Among the various salts available, sodium lignosulfonate and calcium lignosulfonate are commonly used.
Calcium lignosulfonate, also known as wood calcium, is the calcium salt of lignosulfonate. This anionic surfactant, typically a brownish-yellow powder with a slight aromatic odour, boasts excellent adhesion, chelating, and dispersibility properties. However, in formulations, Calcium lignosulfonate reacts with sulphates to form gypsum. Depending on the use, this may disturb some processes or products.
Sodium lignosulfonate, an alternative salt where lignosulfonate is bonded to a sodium ion, stands out due to its natural polymer with excellent dispersibility properties. It does not react with sulphates to form gypsum.
Applications for Calcium and Sodium lignosulfonate include:
- Construction: Used in concrete as a water reducer, dispersant, and plasticiser.
- Mineral Binding: Used in conjunction with minerals to form mineral powder balls, enhancing smelting recovery in kilns.
- Refractory Materials: Acts as an adhesive and dispersant in manufacturing refractory tiles and bricks, improving operating performance.
- Ceramics: Reduces carbon levels and improves green strength in the ceramic industry, enhancing sintering speed and yield.
- Stockfeed: Used to improve pellet quality where less fines are lost, increasing nutrition absorption and weight gain for livestock.
If sulphates are present, Sodium lignosulfonate is more suitable when forming gypsum is not desired.
Other differences:
A main distinguishing feature between the two materials is the counterion and how it interacts with the lignin molecule. Sodium interacts with one sulfonate group while Calcium interacts with two sulfonate groups. The result is that with Calcium, the lignin molecule will be less flexible, leading to a somewhat lower dispersing capacity compared to when the lignin molecule has higher flexibility. It is also worth noting that the dispersion factor can be impacted by the spices of wood (or other raw materials used).
Bisley & Company has been selling sodium lignosulfonate for over 30 years with a strategic partnership with Domsjö Fabriker for Asia, Oceania, and the Middle East regions. Domsjö is the second largest producer of sustainably produced lignin powder in the world. The bioenergy generated by the manufacturing process is used internally and makes them virtually independent of fossil energy sources. They are the only company in the world to have a closed loop bleaching process with zero emissions. For more information on Domsjö please visit their website.
Bisley and Company offer multiple grades of sodium lignosulfonate from Domsjö, contact us today for your requirements.
Please note, that not all products are available in all regions, please check with the local Bisley office for your requirements.