Crude tall oil, also known as liquid rosin, is a amber to dark colour originating from coniferous trees. It is a mixture of mainly fatty acid, rosin, fatty alcohols, unsaponifiable sterols and other alkyl hydrocarbon derivatives. It is the third largest chemical by-product of the kraft process of wood pulp manufacture when pulping coniferous trees. The yield of crude tall oil ranges from 30 to 50 kg/ ton pulp.
Rosin, fatty acid and neutral compounds found in pulp would react with white liquor that is added. This would be separated from the pulp. This liquid known as weak black liquor contains the valuable chemicals which would be extracted in the pulp mill recovery boiler. A layer of soap containing solid material would form on the weak black liquor. The weak black liquor is then evaporated to achieve a dry solid content of 30% to remove the soap layer optimally. The layer of soap is removed during the evaporation step. The layer of soap is called crude sulfate soap. The crude sulfate soap is then cleaned and homogenised before adding sulfuric acid to produce crude tall oil.
Mining and oil Industry
Crude tall oil is used to produce metal working fluids for metal working operations, separating fluids for the concrete products industry and as 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 in phosphate mining.
Crude tall oil can be refined to produce crude tall diesel which is a renewable diesel and a biofuel which can be used in passenger car.
Crude tall oil can be refined to produce products which could be utilised for many industries, including adhesives, rubbers, inks, paint, soap, detergent, lubricants and varnishes.