Supplemental and Recycled Fiber – Fiber Deinking
Wood fiber accounts for more than 90% of the raw material used in the production of paper and board products, and it can come from a variety of sources. These sources can be slushed virgin fiber that is produced onsite, market pulp from other pulp mills, or recycled/secondary fiber. Recycled paper can be broken into several categories including old corrugated containers, mixed paper, and deinking grades. Most deinking grades consist of old newspapers, old magazines and office waste. This course will focus on the equipment and processes used for deinking.
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Learning Objectives
• State the purpose of deinking
• Describe the role of repulping, flotation, washing, dispersing, and bleaching in deinking
• Explain how surfactants are used for deinking
• Explain how flotation deinking works
• Describe process and typical equipment for flotation deinking
• Explain how pulp is deinked by washing
• Describe the process and typical equipment for dispersing
• Describe the process and typical equipment for deinked pulp bleaching
• Describe safety hazards and guidelines associated with recycled fiber deinking
Specs
Course Level | Intermediate |
Languages | English |
Compatibility | Audio, Video |
Based on: | Industry Standards and Best Practices |
Key Questions
What is deinking?
Deinking is the process of removing ink and stickies from recycled pulp. Deinked pulp grades include old newspapers, old magazines, and office waste.
How is ink removed from the paper?
There are several steps. Repulping breaks up the paper and detaches the ink from the fibers. Ink is separated by flotation or washing with the aid of surfactant chemicals.
What are surfactants?
Surfactants are soap-like chemicals that have both hydrophilic and hydrophobic components. Surfactants are used to disperse or collect ink particles.
How does flotation separate the ink?
Surfactants help Ink particles attach to tiny air bubbles that are injected into low consistency pulp. The bubbles rise to the top of a flotation cell and create a layer of foam. The ink-containing foam is removed from the top and the clean deinked pulp is removed from the bottom of the cell.
What is dispersion?
Not all of the ink particles are removed by washing or flotation. Dispersion is a process to disintegrate the remaining ink particles and disperse them in the pulp so they are no longer visible.
Sample Video Transcript
Once ink particles have been detached from the fibers, they can be removed by flotation. Small air bubbles are injected into low consistency pulp, and the mixture is added to a specially designed tank called a flotation cell. With the aid of surfactants, the ink particles attach to the air bubbles, as the bubbles rise to the surface. A layer of foam forms on the surface of the suspension and is removed as rejects. Water is removed from the rejects before they are disposed of.
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