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Wattle Extract Process

Forestry || Saw Milling || Pole Treatment

Wattle Extract and Charcoal Process

Wattle Extract Operations

The Wattle Mimosa  extract processing plant is located on the central estate of Silverstream  which is 150 kilometers south of Mutare along the Chipinge – Chimanimani road.

The factory manufactures three products namely:

  • Solid Mimosa Tannin
  • Green Special Powder
  • Ordinary Powder

The Factory has a capacity of 6500 tonnes of solid extract per year on a sustainable basis.

The factory has been able to produce high quality products and this has been achieved by adhering to high quality control standards. It also helps a lot that the Company controls the entire process from planting the trees to the final product manufacture.

Wattle extract is produced by a process of diffusion. Chopped bark is fed into one of the autoclaves through which heated water is pumped .The resulting solution or (“thin liquor”) has a concentration of approximately 15% extractives and is pumped into holding tanks. The thin liquor is concentrated in one of four multi effect evaporators, where low-pressure steam is used to evaporate water and produce thick liquor of approximately 50% extractives. Finally, in one of four finishers, again using vacuum pumps and steam heating, moisture content is reduced to approximately 18%. The “finished liquor” is bagged in hessian bags and cooled on drying racks, where it solidifies.

The key production criteria are tan content, colour, moisture content and bark to extract recovery percentage.

The heat energy for the process is provided by steam from two Babcock and Wilcox water tube boilers at a rate of up to 10 tonnes per hour. The boilers are fired by wattle wood and spent bark.

wattle extract factory

Inside the Wattle Extract factory

Wattle extraction

Inside the Wattle Extract factory

Charcoal Process

The Charcoal process starts after the Bark stripping process is completed at 9 to 10 year rotation. Destruction of waste crop (DOWC) is done after stripping followed by cross cutting into 2.4m logs. The timber is stacked into a cord measuring (2.4x2.4 x1.8)m weighing 4.15tons. Self-loading tractor drawn trailers are used to transport the cord from infield to kiln deck.

Charcoal production process involves four phases (Charging, burning, cooling and Harvesting)

  • Phase 1 -Each Kiln is manually charged/loaded with 10 cords of charcoal timber.
  • Phase 2 -Burning takes 2 days under the supervision of a kiln burner.
  • Phase 3 -The kiln is allowed to cool for 2 days before harvesting
  • Phase 4 -Harvesting is done manually and packed into 30kg bags . Charcoal bags are put under shade for storage awaiting dispatch.


Wattle extraction

Logs ready to be introduced in to the kilns

Wattle extraction

Kilns in Chimanimani

Sponsored by Wattle Company