Company: SUZ
Filing Date: 2025-04-28
Form Type: 20-F
Source: 0001628280-25-020368
Chunk: 89

Company: Suzano S.A.
Filing Date: 2025-04-28
Form: 20-F
Item: Item 4
Chunk 89
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 the cost of wood for the production of pulp: favorable topographic, climate and soil conditions in the regions of Brazil where we operate; advanced genetic improvement and harvesting technology; low average distances between our planted forests and mills, which are among the shortest in the world; our clone selection system, which improves our forests’ yield and industrial performance, integrating our forestry and industrial activities; and our advanced techniques to maximize soil potential, such as mosaic plantation and minimum environmental impact cultivation techniques. Together, these factors enable us to enjoy: a high and increasing average volume of wood per planted hectare; a higher concentration of fibers per ton of harvested wood; the sustainable development of our operations; relatively low operating costs; and eucalyptus tree harvest rotations of approximately seven years, a period shorter than the harvest rotation periods in other regions of the world.

Table of Co ntents

Pulp Manufacturing

The pulp manufacturing process takes place in two stages:

The “ Kraft” Cooking Process. The logs received in our pulp mills are first de-barked, if not already de-barked in the field, and chipped in small pieces. The wood chips are screened by size and then transferred with conveyors to the impregnation stage followed by a pressurization and feeding system to the digester where they are “cooked” with sodium sulfide and caustic soda. This “kraft” cooking process is known for minimizing damage to the pulp fibers and allows the recovery of chemicals, thereby preserving high uniformity and strength of the fibers for subsequent paper production or other uses. During the cooking process, the cellulose fibers are separated from lignin and other extractive to produce unbleached pulp fibers. The unbleached pulp is then screened, washed and submitted to a pre-bleaching stage where oxygen delignification takes place. The combination of Kraft cooking and pre-bleaching removes approximately 95% of the lignin. At this stage, the pulp can already be used for specific paperboard applications, such as in one of the paper machines at the Suzano mill. Although not our main product, unbleached pulp grades can be commercialized or used in specialty packaging papers or boards. The lignin and other by-products of the Kraft process form a substance known as “black liquor”, which is separated and pumped to evaporators to increase its solids concentration. Thereafter, the concentrated black liquor is burned in recovery boilers, where it serves as the primary fuel for generating steam and electricity to power the entire production process. Also, approximately