3 steps to put a pitch control strategy in place
The smartest approach to a pitch control program for pulp and paper begins with prevention and preparation. Use these three steps to get ahead of pitch.
Step 1: Practice pitch prevention.
You can proactively reduce your need for chemical treatment.
- Manage your woodyard wisely. The less bark the better, with <1% being optimal. Age chips 30 to 45 days for best results. And be aware of seasonal impact on pitch counts.
- Keep a tidy house. Monitor lubrication processes for leaks and quickly respond to missing lubricant inventory. Ensure seals are intact and coolers aren’t leaking oil or hydraulic fluid into cooling water.
- Wash brownstock well. Keep equipment well maintained and under DCS. Operate at the highest temperature possible (>60°C is preferred). Optimize dilution factors. Maintain and manage a well-designed defoamer program with proper feed points and control, using high-quality Buckman defoamer chemistry.
Step 2: Collect data.
The key to a value-based approach to pitch control is knowing your equipment, operating parameters, and systems. To do that, you need quality routine inspection programs and data, lots of data.
- Know your physiology. What’s your grade structure? Do you have hardwood and softwood campaigns? How do seasonal changes impact your pulp?
- Know your process design. Where do you have changes in temperature and pH? Where is the best feed-point selection?
Step 3. Pick a chemical pitch control program that fits.
Based on your mill’s operation, you might need a combination of chemical solutions. Your program mechanisms could include:
- Works best with high temperature and high pH to keep wood acids colloidal in size so they can be easily washed from pulp.
- Fixation or adsorption. Acts as a retention chemistry that uses a polymer to attach the pitch to fiber.
- Breaks down triglycerides in softwoods into more manageable fatty acids and requires a fixative as a follow-up.
- Neutralizes the anionic charge on the resin particles and can stay in the system to help with encapsulated pitch.
- Surrounds colloidal pitch with a hydrophilic shell, typically with alternative pitch control products, such as talc, which becomes an inert filler, remaining in and being sold with the sheet for a profit.
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