What is Crude Tall Oil?

Crude tall fuel, also known as CTO, is a byproduct of the Kraft pulping process used in papermaking. The Kraft process uses a combination of sodium hydroxide and sodium sulfide to break down wood fibers into pulp. This separates the lignin and hemicellulose from the cellulose fibers.

CTO is collected when acids are added to the black liquor formed as a byproduct of the pulping process. This causes the tall oil components like fatty and resin acids to separate from the mixture. CTO contains rosin and fatty acids that make up around 90% of its composition. The exact composition varies based on the type of trees used.

Properties of Crude Tall Oil

CTO is a dark brown or black, highly viscous liquid with a soap-like odor. Some of its key properties include:

- Acid value: Range from 100 to 200, indicating its high acid content. The main acids present are fatty acids like oleic, linoleic, and resin acids such as abietic and pimaric acid.

- Density: Around 1 gram per cubic centimeter.

- Flash Point: Over 93°C, making it classified as a combustible liquid.

- pH: Around 2-4, indicating its acidic nature due to the free fatty and resin acids.

Uses of Crude tall fuel

Due to its unique composition, Crude Tall Oil finds various applications in different industries:

- Drilling Fluids: Used as an emulsifier in oil well drilling operations. Its emulsifying properties help suspend solids in the drilling fluid.

- Concrete Additives: Acts as a set accelerator and water reducer in concrete, improving strength and durability. It enhances both early-age and long-term properties.

- Asphalt Products: Used in asphalt emulsions as an emulsifying agent. It improves the stability and performance of asphalt cement and road surfaces.

- Oilfield Chemicals: Components like tall oil pitch find use as corrosion and scale inhibitors when added to production fluids.

- Metal Working Fluids: Provides emulsification in neat metalworking fluids used for machining and grinding operations.

- Binders & Adhesives: Rosin esters from CTO improve the performance of various paper, construction, and wood adhesives.

Production and Supply of CTO

Globally, over 1 million metric tonnes of CTO are produced annually as a byproduct of the Kraft pulping process. The USA and Scandinavian countries like Sweden and Finland are some of the major producers. CTO prices fluctuate depending on supply and demand forces in different markets. Global manufacturers refine CTO further to produce derivatives like tall oil fatty acid, tall oil rosin, distilled tall oil, etc. These refined products have more specialized applications in niche industries. Overall, CTO remains an important industrial commodity due to the diverse range of products derived from it.

Refining of Crude tall fuel

While CTO can be used directly in some applications, it often requires further refining to isolate and purify individual components for specialized end uses. Common refining methods include fractional distillation, molecular distillation, and catalytic hydrogenation:

- Fractional distillation separates CTO into its boiling point fractions - tall oil pitch with a boiling point over 450°C, tall oil heads between 290-400°C, and tall oil bottoms below 290°C.

- Molecular distillation under vacuum purifies tall oil heads into distilled tall oil with a more consistent composition.

- Catalytic hydrogenation converts unsaturated fatty acids in CTO into more stable saturated ones, producing tall oil fatty acid.

These refined materials like tall oil fatty acid, tall oil distillate and tall oil pitch open up further opportunities in industries like coatings, lubricants, surfactants and oleochemicals. Their purified, well-defined nature suits stringent modern applications.

As the global pulp and paper industry continues to grow with rising demand, CTO production is projected to increase steadily in the coming years. With environmental regulations tightening around the world, biobased materials like CTO will gain more importance due to their sustainability credentials over fossil fuel-based alternatives. Constant research further broadens the range of applications leveraging CTO’s unique functional properties. The market for CTO derivatives is also expanding into higher value specialty product segments. Overall, crude tall fuel is poised to remain a crucial renewable resource supporting diverse industries into the future.

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