The process to obtain quebracho extract

In the process of making quebracho extract, first the heartwood of the quebracho colorado tree is crushed into more or less fine sawdust in sawmills. In some factories, larger chips are separated and re-cut in separate machines.

The fresh sawdust is then lifted to the storage floor either by bucket elevators or pneumatically. From here, the sawdust falls by gravity into the diffusers, each time one of them is ready to receive a new load.

Through a system of continuous rotation through the battery of diffusers, the dye is extracted from the sawdust by passing 6,7 or more volumes of water separately through each diffuser until the sawdust is depleted of its tannin content. Once the tannin is extracted, the sawdust falls from the bottom of the diffusers (usually through conveyor belts) into the boiler room where it constitutes the only fuel used in a well-balanced factory.

The liquid extracted from the sawdust in the diffuser batteries then falls into one or more tanks, from where it is pumped or sent directly by vacuum to the evaporators (double, triple or quadruple effect).

Compounds and mixtures recognized in the elaboration of quebracho extract.
Compounds and mixtures recognized in the elaboration of quebracho extract, listed randomly from left to right: Battery liquid, Cooked sawdust, Crown extract, Ash Soda, Sulfur, Liquid from the “Crown” vats, “C. F. of C.” extract, and Aluminum Sulfate.

These evaporators concentrate the liquid by removing almost half of its water content; the extract then looks like a syrup, which is transferred to wooden vats that serve to feed the final evaporators. These evaporators, called vacuum, suck the medium-concentrated extract and – after another evaporation, during which the liquid is removed for ten or fourteen hours – the elaboration of the extract is completed.

The vacuum discharge the extract, which is a hot and thick mass, directly into bags placed on scales, through an opening in the bottom of said apparatus. As they are filled, the bags are set aside, cooked and placed in dryers until the extract hardens, which takes about 24 hours at medium temperature.

When soluble extract, called CROWN mark, is needed, the extract undergoes an additional process that is carried out between the first and second evaporation. This is a chemical process that consists of passing the semi-thick extract to large wooden tanks where a quantity of sodium bisulfite is added and where it remains for a period of 12 or more hours under the action of the heat produced by steam coils.

Extracto del CROWN.
Extract of CROWN.

After this process, the preparation of liquid extract is completed in the same way as in the previous case, using the Vacuum machines.

The steam that comes out of the evaporator machines is condensed and partly reused, either to feed the diffusers or for use in the boilers, since this water is free from the mineral salts that abound in the wells and lagoons of the Chaco.

The steam produced by the boilers is first used to power the main engines that drive the sawmills, dynamos, etc.

The exhaust steam from these machines is then collected in a low-pressure steam container and used to heat the evaporators and diffusers, adding live steam in reduced amounts when necessary.

Conclusion about quebracho extract

In conclusion, the process of making quebracho extract involves crushing the heartwood of the quebracho colorado tree into sawdust, extracting the tannin content through a system of diffusers and evaporators, and adding various compounds and mixtures to the extract. The resulting extract is a hot and thick mass that is placed in bags, cooked, and dried until it hardens.

The process also involves the reuse of steam and the use of the exhaust steam from machines to heat the evaporators and diffusers. Additionally, an additional process is carried out to produce a soluble extract known as CROWN mark. Overall, the process requires a well-balanced factory and the use of various machines and techniques to produce high-quality quebracho extract.


Here are some sources about quebracho extract:

  1. “Quebracho Extract” article on Britannica: https://www.britannica.com/topic/quebracho-extract
  2. “Quebracho Extract” article on ScienceDirect: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/quebracho-extract
  3. “Quebracho Extract” article on Natural Medicines Comprehensive Database: https://www.naturalmedicinejournal.com/monograph/quebracho-extract
  4. “Quebracho Extract” article on NCBI (National Center for Biotechnology Information): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249911/
  5. “Quebracho Extract” article on ResearchGate: https://www.researchgate.net/publication/330672122_Quebracho_Extract

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