Kimia Industri - Pembuatan Pulp dan Kertas (Diagram Alir proses) (Bag. 2 - Akhir)

Pulp Preparation Process (Pulping)
📌 The initial stage involves Wood Preparation (Pulping), starting with logs (2-3 meters long, 30 cm diameter) transported via conveyor belt to the debarker for bark removal.
🪵 After debarking, wood goes to the chipper where it's turned into chips, which are then accumulated in a chip storage.
🌲 Standard chips must measure 10-25 mm in length, 10-25 mm in width, and 5-8 mm in thickness, separated using a vibrating screen.

Pulp Cooking and Washing
🔥 The chips enter the cooking stage in a large pressurized vessel called a digester along with white liquor ($\text{NaOH} + \text{Na}_2\text{S}_4\text{O}$).
🧼 After cooking, the mixture undergoes washing stages, starting with demi-inking to remove knots, followed by screening (using a flat screen) to separate impurities based on size and density.
💧 Further washing uses a rotary washer system to separate fibers from water-soluble organic and inorganic impurities left in the black liquor.

Pulp Bleaching and Finishing
🔬 Oxygen delignification reduces lignin content using oxygen gas and $\text{NaOH}$ before the main bleaching sequence, resulting in unbleached pulp.
✨ The bleaching process enhances brightness and cleanliness, typically involving four stages: Chlorination ($\text{Cl}_2$ and $\text{CO}_2$), Alkali Extraction ($\text{O}_2$, $\text{NaOH}$, and $\text{H}_2\text{O}_2$), and two subsequent re-bleaching steps ($\text{D}1$ and $\text{D}2$ using $\text{CO}_2$).
📰 The final pulp machine stage filters the pulp, dewaters it (reducing water content to 10% via presses like the netrol), dries it using hot steam cylinders, and cuts it into standardized bales.

Paper Manufacturing Process
🥣 Raw material enters stock preparation where additives like dyes and retention agents are mixed, creating a final product called stock before entering the headbox.
💧 The headbox forms the paper sheet on the fourdrinier table, which drains water, resulting in a wet web (paper with high moisture content).
🌡️ The web proceeds to the press section (squeezed between two rotating rolls) and then the drying section, where it passes over heated cylinders until the moisture content reaches about 6%.
📏 The dried paper moves to the calender for smoothing and thickness control, then to the pop reel to form a jumbo roll, which is then re-wound, cut, and finished according to customer specifications.

Key Points & Insights
➡️ The wood preparation process meticulously sizes wood chips (10-25 mm x 10-25 mm x 5-8 mm) to ensure proper chemical reaction during cooking.
➡️ Black liquor is the byproduct containing lignin removed during cooking, while the final paper moisture content target after drying is 6%.
➡️ The paper machine uses mechanical pressure in the press section and heat in the drying section to efficiently remove water from the nascent paper sheet.

📸 Video summarized with SummaryTube.com on Dec 08, 2025, 09:21 UTC