I. Basic Process Flow of Bamboo and Wood Pulp Production

Basic Process of Slurry Production:

Grind Slurry

Solid Wood StorageSawing → Debarking, De-jointed → Planing → Steam Treatment → Washing → Screening, Purification → Bleaching → Bleached Pulpboard

→ Dipping and Milling → → Natural Color MDF Board

2. Process Introduction:

The Role of Solid Wood Storage: 1. Maintaining Normal Continuous Production in the Factory 2. Improving Raw Material Quality

Original Wood Storage Methods: Aquatic Storage; Terrestrial Storage

Logs are cut to a specified length to meet the requirements of subsequent processing stages. The chipper requires logs to be 2-2.5 meters in length, while the planer demands logs between 0.6-1.2 meters.

Peeling: Due to the low fiber content and high impurity levels in the bark, it reduces cooking efficiency, increases the consumption of cooking chemicals, and leads to an increase in dust in the pulp and a decrease in strength. Therefore, when producing high-quality pulp with stringent quality requirements, it is generally necessary to remove the bark.

To avoid the impact of knots on the quality of the grinding stone and wood pulp during the wood grinding process, the wood logs sent to the grinding machine must be free of knots.

Sawing: To accommodate the cooking process of chemical wood pulp and meet the production needs of wood chip pulping, logs must be sawn into chips. The chips should be uniform in length, thickness, and width. Standard chip dimensions are typically 15-20mm in length, 3-5mm in thickness, and although width is not strictly limited, it is preferred to not exceed 20mm. After sawing, the chips must be sifted through a round sieve, with a requirement for a minimum 85% pass rate for the raw log chips.

Pulping: It refers to the production process of converting plant fiber raw materials into pulp (unbleached pulp) or further bleached into bleached pulp by chemical methods, mechanical methods, or a combination of both.

Chemical Pulp Production: This involves the use of chemicals to dissolve most of the lignin from the plant fiber raw material under specific conditions, causing the fibers to disperse into pulp. The cooking process is primarily a lignin removal process. However, it inevitably leads to some degree of degradation of cellulose and hemicellulose. As a result, the yield of chemical pulp is generally low, around 50%.

2. Pulping: The process of grinding fibrous raw materials into pulp using mechanical methods.

Primarily divided into two categories.

Wood chip pulping: The wood chips enter between the discs of the disk mill, first being broken into match-like shapes, and these match-like strips are then rubbed and decomposed into single fibers or fiber bundles.

Wood Chips Production: Logs of a certain length are fed into a wood grinder, where they undergo compression and shearing by abrasive stones under specific pressure and temperature. This process breaks down the logs into individual fibers or fiber bundles.

3. Chemical Pretreatment (Dipping): The primary task of chemical pretreatment is to soften the fibers, relaxing the fiber structure for better pulping suitability.

Washing: After pulping fibers are cooked, approximately 15-50% of the material dissolves in the cooking liquor. The cooking liquor drained at the end of the cooking process is collectively referred to as waste liquor. The purpose of washing is to thoroughly clean the pulp while extracting cooking liquors with high concentration and temperature, which are then used in the alkali recovery process to recover organic or inorganic substances from the waste liquor. Chemical pulp still contains undissolved components after washing. Coarse fiber bundles, and groundwood pulp also contain coarse wood chips, large wood pieces, and coarse fiber bundles. Additionally, during the collection, transportation, storage, and production processes, debris such as mud, fly ash, wires, and plastics may enter. These substances not only affect the quality of the paper but also damage machinery and equipment, hindering the smooth progress of production. Therefore, screening and purification are used to remove these impurities.

The bleaching process primarily aims to remove colored substances within the fibers, resulting in pulp with a certain degree of brightness and appropriate physical and chemical properties.

The color of pulp primarily originates from lignin and extractives. There are two types of bleaching methods:

'Extractive Bleaching' involves using appropriate bleaching agents to dissolve lignin through oxidation, thereby achieving the bleaching purpose. This includes methods such as chlorine bleaching, hypochlorous bleaching, chlorine dioxide bleaching, and peroxochlorine bleaching. This method is often used when high paper pulp brightness is required, and it is commonly employed for chemical pulping.

2. 'Lignin-retaining bleaching' preserves lignin while only de-colorizing the chromophore groups. This method results in minimal loss and retains the pulp's properties. Examples include bisulfite bleaching and sodium borohydride bleaching. These methods are commonly used for the bleaching of high-yield pulp.

Relevant Concepts:

Element-Free Chlorine BleachingECF: The bleaching process does not contain free chlorine elements, such as hypochlorite bleaching and chlorine dioxide bleaching.

All Chlorine-Free Bleach-Free:TCF: No chlorine-based bleaching agents are used during the漂泊 process, such as hypochlorite bleaching or ozone bleaching.

Section II: Refining Process for Chemical Pulp or Mechanical Pulp

Chipped bamboo wood → Chip tearing machine → Washing machine → Chip dewatering → Steam or soak → Spiral conveyor → Pulp dewatering and concentration → Carding or tearing fibers → Spiral conveyor → High concentration pulp grinding → Insulation reaction → Dispersing → Medium concentration pulp grinding → Washing and pressing filter → Finished pulp cake