What Is a Paper Mill? How Paper Mills Work

What Is a Paper Mill? How Paper Mills Work

May, 2024

A paper mill is an industrial plant that turns wood fiber, recycled paper or both into rolls of paper and paperboard. Logs or recovered fiber are broken down into pulp, the pulp is cleaned and formed into a wet sheet, and the sheet is pressed, dried and wound into large rolls that go on to box plants, printers and converters.

Paper mills are industrial facilities that efficiently convert raw materials into high-quality paper products while minimizing waste and environmental impact. Their main processes involve optimizing production to ensure the consistent quality and quantity of paper output. They strive to remain competitive by controlling production costs and meeting customer demands for diverse paper products.

In this article, we look at the history of paper mills, the main types, how a mill works, and what Hood Container’s own paper mills produce.

History of Paper Mills

The earliest known papermaking techniques date back to around 2,000 years ago. Initially, paper was handmade using natural fibers such as mulberry bark, hemp, and rags. These fibers were beaten into a pulp, which was spread onto a flat surface, pressed, and dried to form sheets of paper.

The invention of the water-powered paper mill in medieval Europe marked a significant milestone in the history of paper production. Watermills supplied an efficient power source, allowing for the automation of various phases of the papermaking process. By the 13th century, paper mills had been constructed in Spain and France. They made paper for writing, books, and other uses.

The Industrial Revolution of the 18th and 19th centuries resulted in additional advances in paper mill technology. Steam power replaced water as the primary energy source, enabling larger-scale production and higher processing rates. Innovations like the Fourdrinier machine further revolutionized papermaking by automating the continuous manufacture of paper sheets.

Key Elements of a Paper Mill

Here are the fundamental components comprising standard paper mills:

Wood Handling and Preparation

The first key element is wood handling and preparation, where raw materials such as logs or wood chips are received and processed. This process involves debarking, chipping, and screening the wood to create suitable fibers for papermaking.

Pulping Process

The pulping process encompasses mechanical or chemical methods to separate the fibers and remove impurities. The quality and characteristics of the pulp significantly influence the final paper product’s strength, texture, and appearance.

Paper Machine

The paper machine is the central component of paper mills, where the actual paper production takes place. It consists of various sections, including the headbox, wire section, press section, drying section, and reel. Each section plays a crucial role in transforming the raw materials into finished paper products through mechanical and chemical processes.

Chemical Recovery System

Chemical recovery systems recover cooking chemicals and convert organic compounds into usable byproducts, such as lignin and tall oil. They help paper production facilities optimize resource utilization and reduce dependency on external chemical sources.

Stock Preparation

Stock preparation processes raw materials into a suitable pulp for papermaking. This stage includes pulping, refining, and blending, where raw materials like wood chips or recycled paper are transformed into a uniform pulp mixture.

Roll Handling and Winding

Roll handling and winding begin with the unwinding of parent rolls and progress through various stages, such as slitting, rewinding, and packaging. Efficient roll handling ensures smooth production flow, limits downtime, and maintains product quality, making it an essential aspect of papermaking operations. It also contributes to workplace safety by reducing the risk of accidents associated with handling heavy rolls.

Water and Effluent Treatment

Paper mills utilize advanced treatment processes to purify water used in various production stages and treat wastewater before discharge. Efficient water management strategies help reduce environmental impact and minimize water consumption. Meanwhile, stringent effluent treatment ensures compliance with regulatory standards for water quality.

Types of Paper Mills

Not every paper mill works the same way. The fiber a mill starts with, and what it makes, shape the whole operation.

• Kraft (virgin fiber) mills cook wood chips with chemicals to separate out strong, long fibers. They make the tough kraft linerboard and kraft paper used where strength matters.
• Recycled mills use old corrugated containers and other recovered paper as their main fiber source, pulping it with water rather than cooking wood.
• Semi-chemical mills use a lighter chemical cook that keeps more of the wood, producing a stiff fiber that is ideal for corrugating medium.
• Integrated mills make their own pulp on site. Non-integrated mills buy pulp and focus on forming and finishing paper.

What Paper Mills Make for Corrugated Packaging

Most people never see mill output in its raw form, but they handle it every day. A corrugated box is built from two paper mill products:

• Linerboard: the flat outer and inner faces of the board. Kraft linerboard gives a box its printability and its burst and crush strength.
• Corrugating medium: the wavy, fluted layer glued between the liners. The flutes are what give corrugated board its stacking strength and cushioning.

Box plants combine the two on a corrugator, then cut, print and fold the board into finished boxes and displays. Want the difference spelled out? See corrugated vs. cardboard.

Inside Hood Container’s Paper Mills

Hood Container runs two paper mills that supply its corrugated plants and outside customers.

• St. Francisville, Louisiana: on the Mississippi River in West Feliciana Parish, the mill produces kraft linerboard and kraft paper grades. In 2020 Hood announced a $50 million efficiency upgrade and capacity expansion at the mill.
• New Johnsonville, Tennessee: the mill produces a range of semi-chemical medium grades used for corrugating medium.

Owning the mills means Hood controls paper quality from fiber to finished box. See grades and specifications on our paper mills page, or find both mills on our locations map.

Paper Mill FAQs

What is the difference between a paper mill and a box plant?

A paper mill makes paper and paperboard in large rolls. A box plant (or corrugated plant) buys those rolls and converts them into corrugated sheets, boxes and displays.

Is “papermill” the same as “paper mill”?

Yes. Both spellings refer to the same kind of facility; “paper mill” is the standard form.

What raw materials does a paper mill use?

Wood chips and logs, recovered paper such as old corrugated containers, water, and process chemicals. The mix depends on whether the mill is kraft, recycled or semi-chemical.

How do paper mills reduce their environmental impact?

Common practices include recovering and reusing cooking chemicals, burning wood by-products for energy, and treating process water before it is returned. Kraft mills’ chemical recovery systems are a core part of that.

Choose Hood Container for Paper Products and Packaging Solutions

At Hood Container, we deliver innovative solutions tailored to meet the unique needs of our clients in the paper and packaging industry. Leveraging advanced technology and sustainable practices, we ensure the highest quality standards in paper production and packaging solutions. Our commitment to excellence extends to every aspect of our operations, from raw material sourcing to final product delivery.

Need linerboard, medium or kraft paper, or corrugated packaging made from it? Talk to our team.