Crude Tall Oil, also known as Tall Oil, is a mixture of mainly fatty acid, rosin, and other neutral material compounds. It is produced from coniferous trees and has a variety of uses. It is obtained as a co-product of the Kraft wood pulping Process used by paper mills and it is the third largest chemical by-product of Kraft mill. Crude Tall oil is a viscous yellow-black odorous liquid and its composition varies a lot depending on many factors like wood furnish used, the process used to obtain oil etc. The quality of crude tall oil is measured depending on their acidic number.
Crude tall oil is a complex combination of tall rosin and fatty acids. Hence, the molecular and structural formulae, melting and boiling point cannot be determined.
Tall Oil is extracted from pulp and paper mills where the "black liquor" produced is concentrated and left to settle. Tall Oil Soap that is settled at the top layer is skimmed off and reacted with an acid to form crude tall oil. The crude tall oil produced is further processed through distillation where distilled tall oil is obtained.
Mining and Oil Industry
Crude Tall Oil is used to produce metalworking fluids for metalworking operations, separating fluids for the concrete products industry and as a flotation agent for the mining industry. Also, crude tall oil is used as drilling fluid emulsifiers and wetting agent in oil-based drilling operations. Their derivatives and products are also used in additives for drilling operations and corrosion inhibition.
It is also used as lubricating greases and as a drying agent in the paint industry. Crude Tall oil is used as emulsifier and solvents in soaps and detergent industry. They have few highly unsaturated acids so they provide good oxidative, color and viscosity stability. They are biodegradable and are inexpensive.