La liqueur verte, un élément essentiel du procédé de fabrication du papier kraft, est le résultat de la dissolution de la fonte fondue - un mélange de sulfure de sodium, de carbonate de sodium et d'autres produits chimiques - dans l'eau. Cette liqueur, caractérisée par sa couleur verte due à la présence d'impuretés de fer, joue un rôle crucial dans le cycle de récupération chimique du procédé kraft.
Le Rôle de la Liqueur Verte dans la Fabrication du Papier Kraft :
Propriétés de la Liqueur Verte :
Implications Environnementales :
Conclusion :
La liqueur verte, malgré son nom quelque peu sinistre, est un élément crucial du procédé durable de fabrication du papier kraft. Son rôle dans le cycle de récupération chimique garantit la réutilisation efficace des produits chimiques et minimise l'impact environnemental. Comprendre les propriétés et les fonctions de la liqueur verte est essentiel pour optimiser l'efficacité et la durabilité des usines de fabrication de papier kraft.
Instructions: Choose the best answer for each question.
1. What is the primary reason for the green color of green liquor?
(a) The presence of sodium sulfide (Na₂S) (b) The presence of sodium hydroxide (NaOH) (c) The presence of iron impurities, mainly ferrous sulfide (FeS) (d) The presence of calcium oxide (lime)
(c) The presence of iron impurities, mainly ferrous sulfide (FeS)
2. What is the key function of green liquor in the kraft process?
(a) To provide a source of heat for the pulping process. (b) To act as a bleaching agent for the pulp. (c) To provide essential chemicals for the pulping process. (d) To neutralize the acidity of the wood chips.
(c) To provide essential chemicals for the pulping process.
3. What is the process called where green liquor is converted into white liquor?
(a) Decolorization (b) Causticizing (c) Smelting (d) Dissolving
(b) Causticizing
4. What is a significant environmental benefit of the kraft process, which utilizes green liquor?
(a) Reduced air pollution from burning fossil fuels (b) Minimized waste and maximized resource efficiency through a closed-loop system (c) The ability to use recycled paper as a raw material (d) The production of biodegradable paper products
(b) Minimized waste and maximized resource efficiency through a closed-loop system
5. What is the typical pH range of green liquor?
(a) 1-2 (b) 5-6 (c) 9-10 (d) 13-14
(d) 13-14
Scenario: A kraft paper mill produces 1000 tons of pulp per day. The process requires a specific concentration of sodium sulfide (Na₂S) in the green liquor to maintain optimal pulping efficiency. Currently, the green liquor contains 10% Na₂S by weight. However, the desired concentration is 15%.
Task: Calculate the amount of sodium sulfide (Na₂S) that needs to be added to the green liquor to achieve the desired concentration.
Instructions: 1. Determine the current weight of Na₂S in the green liquor (assuming a constant green liquor weight). 2. Calculate the target weight of Na₂S required for the desired concentration. 3. Subtract the current weight of Na₂S from the target weight to find the amount to be added.
Let's assume a constant green liquor weight of 1000 tons for simplicity. 1. **Current weight of Na₂S:** 1000 tons * 10% = 100 tons 2. **Target weight of Na₂S:** 1000 tons * 15% = 150 tons 3. **Amount to be added:** 150 tons - 100 tons = 50 tons **Therefore, 50 tons of sodium sulfide (Na₂S) need to be added to the green liquor to achieve the desired 15% concentration.**
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