by Crude tall fuel is a byproduct of the Kraft pulping process used to produce paper. This process involves treating wood chips or pulp with a hot solution of sodium hydroxide and sodium sulfide, known as white liquor, to separate lignin from cellulose fibers. Lignin is dissolved and separated from the cellulose fibers, which are then processed into paper.
The black liquor that is skimmed off from the digestion tanks contains dissolved lignin and other wood extractives. This liquor is concentrated in multiple effect evaporators and then burned to recover chemicals for recycling and provide steam and power for the pulp mill. When burned, the tall oil components in the black liquor volatilize and condense to produce crude tall fuel. On average, approximately 130 pounds of crude tall fuel can be derived from every ton of pulp produced.
Composition and Properties of Crude tall fuel
Crude tall fuel consists of resin and fatty acids derived from the esters of resin acids in coniferous trees such as pine. It is a dark brown or black viscous liquid with a disagreeable odor. The main components are resin and fatty acids such as oleic acid (C18:1), linoleic acid (C18:2), linolenic acid (C18:3) and palmitic acid (C16:0). It also contains small amounts of sterols, waxes and other compounds.
Due to its mixture of acids, alcohols and compounds such as sterols, crude tall fuel exhibits both acidic and fatty properties. It is emulsifiable in water and dissolves in organic solvents such as alcohol. Its acid value typically ranges from 100 to 150 mg KOH/g. The mixtures of compounds give crude tall fuel corrosion inhibiting properties beneficial for uses such as rustproofing.
Uses of Crude Tall Oil such as tall oil fatty acids in lubricant additives and mineral processing contribute the most to demand.
Applications and Uses of Crude Tall Oil
Crude tall fuel finds various industrial applications by taking advantage of its acidity, emulsifiability and surface active properties:
– Due to its mixture of fatty and resin acids, crude tall fuel is used as an additive in lubricating oils and greases to improve their resistance to waterwashout and corrosion protection.
– It is used as a dispersing and wetting agent in the formulation of agricultural chemicals, pesticides, fertilizers and other products. The fatty acids help disperse active ingredients in liquids or powders.
– Crude tall fuel soaps produced by neutralizing the acids find use as emulsifiers in cosmetics, toiletries and other personal care products.
– Its surface active properties allow use as a floating agent in froth flotation processes to recover sulfide ores and other minerals.
– It acts as a binder in foundry sand mixtures, improvingcasting properties. The fatty acid resins coat and strengthen sand grains.
– Other applications include use as a drift control agent, gelling agent, corrosion inhibitor and flotation collector in the mining industry.
Processing and Refining of Crude tall fuel
Crude tall fuel undergoes further processing depending on desired end product properties:
– Distillation separates crude tall fuel into different fractions like tall oil fatty acids, tall oil distillate and tall oil heads in order to recover and utilize individual components.
– Caustic washing removes water-soluble rosin components, producing tall oil soap stock. Additional bleaching produces bleached tall oil soap.
– Hydrogenation raises the melting point and oxidative stability of unsaturated fatty acids, producing hydrogenated tall oil useful as a softening agent.
– Fractionation separates refined fractions suitable for specialized applications such as dimer acids used in oilfield chemicals or oleic and linoleic acids used in cosmetics.
– Esterification reacts tall oil acids with alcohols to produce tall oil fatty acid esters finding application as lubricating oil additives, surfactants and emulsifiers.
Market and Economics of Crude tall fuel
The global market for crude tall fuel in 2019 was estimated at over 850,000 metric tons annually. The main regions of production are the Nordic countries, Baltic states and Russia where conifer trees are abundantly available.
Uses of crude tall fuel such as tall oil fatty acids in lubricant additives and mineral processing contribute the most to demand. However, expanding applications in areas like biodiesel feedstock, bio-based binders and surfactants are boosting market growth.
Prices of crude tall fuel fluctuate depending on supply and demand forces but generally range between $500-700 per metric ton. The byproduct provides valuable additional revenue streams for pulp mills to boost profits from their operations. Overall, crude tall fuel is an important substance extracted from the Kraft pulping process with a variety of commercial uses.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
