Recovery and utilization of recovered paper have risen persistently over a couple of years globally. Papermaking has become one of the topmost recycling industries as it is based on important complementary between pure and recovered fibers.
Enhanced removal of adhesives, “stickies”, from pure pulp fibers or recovered paper is done by using a combination of enzyme treatments, along with absorbents. There is an array of control methods such as improved pulping end deflaking, furnish selection, well-designed screening end cleaning systems, and many more.
Problem of Stickies
A massive number of contaminants are introduced to nature with recovered paper, and because of this, it becomes the primary aspect of the recycling process. To solve this issue, a high number of stickies control chemicals are used during papermaking.
Control of Stickies
Stickies can be controlled in two ways; one is by removing the stickies to the maximum possible extent. The second method is the prevention of the remaining stickies to the deposits. Remember the mills should always first try to remove the stickies and then do deposit control.
The reason behind it is that deposit restraint is done to diminish the disturbing effect of the stickies, which cannot be removed. Removal of stickies is a secure method and can be done speedily where there is a reject stream.
There are various steps taken to remove stickies, such as pulping, screening, cleaning, floatation, and usage of multiple chemicals.
Types of stickies control
There are various stickies control chemical suppliers in the market, but you must know about them in detail so that you know which one to opt for. Below mentioned are some of the different chemicals and ways to control stickies-
- Using Benotine– If benotine is used with polyethylene oxide, it works really well as an efficient retention system which dramatically improves the stickies removal. In this process, the stickies are fixed by the chemicals onto the fibres and removed from the process by the paper sheet.
- Using Diatomite– This mineral comprises of skeletal remains of single-celled aquatic plants. It has organophilic and hydrophilic parts which make it a perfect product for stickies removal.
- Cationic Polymers- Using this is pretty common in deinking and recycling mills. These polymers are usually used in the pulping process as they help in preventing the formation of secondary stickies. Perhaps, the motive of using cationic polymer is to induce controlled precipitation of the colloidal contaminant and their fixation onto the fibres so that they can be removed easily from the paper sheet.
- Surfactant- Using surfactant does not remove the stickies entirely, but it can modify the surface properties of it. A surfactant can also be used for treating paper machine clothing like wires or felts.
- Enzymes- This is an entirely new approach which breaks the bigger stickies into smaller ones, and then it can be eliminated from the mil process. The best part of this approach is that it lessens the impact on paper quality and brightness.
In this process, esterase enzymes are used for breaking the stickies into smaller ones.
- Alum sequestering agents- Alum is being used in this process to ensure better retention and standard sizing. While using alum, you should always be vigilant about the quantity of alum as an excessive amount might lead to coagulation of stickies in the secondary fiber stock.
- Solvents and dispersants- There are two types of dispersants, anionic and nonionic polymers. If dispersants are mixed well with solvents, they can help well in defibering of wet-strength pages. You should always choose dispersants as per its compatibility with the existing system.
Conclusion Controlling of stickies is not an easy task in deinking or recycling mills. Various approaches can be used. But, every mill has a particular case, and so you should choose the best solution after doing proper research.