Lignosulfonate Lignin used across agriculture, fertilizer manufacturing

Lignin sulphonates, also referred to as lignosulphonates or lignin sulphonic salts, are by-products of paper production. Wood, the base material from which most paper is made, is primarily composed of two types of materials: carbohydrates (such as cellulose and hemicellulose) and lignins. Lignins are molecularly complex and diverse, and difficult to break down. They are undesirable within most paper, so the lignin is extracted by cooking the woody material under pressure with sulphite chemicals. This process produces a liquor containing sulfonated lignin called lignosulphonate. The liquor is purified through fermentation, which produces alcohol that is removed. During these processes, the chemicals that are used can create various lignin sulphonic salts, such as sodium lignosulphonate, calcium lignosulphonate or magnesium lignosulphonate.

Lignin sulphonate is restricted to use as a chelating agent, formulant ingredient or dust suppressant under the COR standards. Chelated micronutrients are widely used to meet nutrient deficiencies in crop production. Formulants may be used in conjunction with other substances found on the Permitted Substances Lists, and are commonly used in pesticides or fertilizers as inert materials. Dust suppressants are widely used across agriculture, fertilizer manufacturing and erosion control. Lignin sulphonate also has a large variety of uses outside the organic industry, including uses in the manufacture of concrete, plasterboard and tanning leather, as a deflocculating agent in linoleum flooring and coal briquettes, and as a fire retardant.

Lignosulfonate is used in many processes and products and seems to be a chemical under considerable development. It works on the surface of particles, both in dry systems and in water solutions. In dry systems lignosulfonate forms a layer on the particle surface, thus increasing the particle size and making the particles bind together. In water solutions the hydrophobic parts of the molecules bind to the dispersed particle, while the hydrophilic part bind towards water and thus the particle is kept in solution. The largest use of this substance is as a cement additive where it binds to the surface of the cement particles and delays the absorption of water, which is the hardening. The additive also influences the structure of the hardened cement.