29 août 2017 14:35 Laisser vos pensées
This week, I would like to give a brief overview of how the pulp mill works! So many people I’ve talked to from home don’t even really know what pulp is, so this seems like a good opportunity to explain what it is and how it’s made.
When people ask me what pulp is, I always describe it as an intermediate step between wood chips and any type of paper or boxboard product (including tissue, paper towel, cardboard, etc.). Pulp is used in so many different processes and is in things most people don’t even think of! So now, how is pulp made? Pulp can be made in a couple different ways – mechanically or chemically. In the Taylor mill, we use a process called Bleached Chemi-Thermomechanical Pulping (BCTMP). This is a process where the chips are broken down using energy in refiners and then those fibers are bleached to a desired brightness.
As a process engineering co-op student at the mill, it is very important for me to understand how fiber flows through the mill and where specific equipment is. I have found one of the best ways to help me learn the process is to go for a walk through the mill. On my most recent walk, I snapped a few pictures of key areas!
The first step of our process is getting chips into the mill! The majority of the chips we receive are the waste wood left over from the Fort St. John and Chetwynd sawmills. We are also able to chip our own logs on site. Here is a picture from the top of the conveyer that brings chips into the mill.
After the cleaning stages, the pulp goes into medium density storage towers. This is a very important part of the mill as it is the division between the refining end of the mill and the bleaching end. If the refiners need maintenance and there is no pulp being made, the medium density storage towers can still be pulled from and feed the bleach plant. This works both ways! If there is any maintenance that needs to be done in the bleach plant, the refiners can continue to be run and feed pulp into the towers! So smart.
The next stage of the process is the bleach plant. There are two stages of bleaching where chemicals are added in order to brighten the pulp and remove yellowing. Brightness is an important quality for all of our customers and varies based on each customer’s needs. (I would change this to a sentence that briefly explains we control the process to satisfy other quality parameters as well, such as tensile strength and debris content)
After the bleaching process, it is important to remove moisture from the pulp to ensure the most effective shipping. The bleached pulp goes through a flash drying system which removes a large amount of the moisture from it. Many people assume that smoke is coming out the stacks at our mill, but it’s actually just steam! Once the moisture is removed from the pulp, it is pressed into bales and sent to the finishing line where it is wrapped and prepped for shipping.
This was a VERY brief overview of what happens in our mill, but I hope it gives a little insight into how we do things. It’s pretty cool!