Waste slab recovery system and its improvement measures in particleboard production

Unqualified slabs (waste slabs) from particleboard production need to be removed and recycled. Currently, two recycling methods are commonly used both domestically and internationally: scraper conveyors (see Figure 1) and pneumatic conveying systems (see Figure 2). Each recycling method has its advantages and disadvantages, and each factory will choose the appropriate method based on its site layout and installation space.

1. Scraper conveyor waste slab recovery system

1) Advantages. First, it offers a compact structure. The process layout for conveying scrap slabs using a scraper conveyor requires the scrap slab silo to be as close as possible to the recovery section of the forming line, saving space. Pneumatic recovery systems, on the other hand, require significantly more space than scraper conveyors and require air ducts, cyclones or bag filters, fans, and other equipment. Second, it offers low investment. A single high-angle scraper conveyor can convey scrap slabs directly to the scrap slab silo. Third, it offers low power consumption. Scraper conveyors have high conveying capacities and operate at slow speeds, so their installed power is far less than that of pneumatic recovery systems. The number of power configuration points, including fans, discharge screws, and rotary discharge valves, also exceeds that of scraper conveyors.

2) Disadvantages. First, the large inclination angle of a scraper conveyor requires very high manufacturing and operational monitoring requirements. Second, maintenance costs are high. The scraper conveyor's scraper chain, sprockets, scrapers, and running tracks are all wearing parts. Replacing damaged parts is not only expensive but also time-consuming.

2. Pneumatic recovery of waste slab system

1) Advantages and disadvantages.

The advantage of a pneumatic waste slab recovery system is that it's not constrained by layout or installation space. However, many projects are limited by site layout, where the recovery silo is located far from the paving section, or the height of the silo is not suitable for conveying with a scraper conveyor, leaving them with the option of a pneumatic recovery system. However, the disadvantages are that the investment is greater than that of a scraper conveyor, the operating power consumption is relatively high (this can be reduced through appropriate frequency conversion and electronic control), and the recovery process is prone to blockage.

2) Technical improvement measures to solve the problem of easy blockage of pneumatic waste slab recovery system.

3 Conclusion

The proper functioning of the waste slab recycling system in particleboard production is crucial. Immediate slab recovery is crucial in the event of metal alarms, substandard slab quality and moisture content, or malfunctions in the press or post-processing stages. Blockages in the recycling system are a common problem during production. Blockages force the paving system and preceding processes to halt, impacting production efficiency and causing product quality fluctuations. Limited process space makes blockage removal inefficient and time-consuming, resulting in harsh, dusty conditions and significant maintenance workload for operators. Through practical and exploratory technical improvements, the blockage problem in the pneumatic waste slab recycling system has been completely resolved. This simple, practical, and cost-effective solution is worthy of industry reference and emulation.

Authors: Chen Yaoli1, Shen Jiaxiong1, Zhang Lizhen1, Meng Qingyou1, Xiong Xiangwei2, Xu Yeming3

Institutions: 1. Shandong Heze Maosheng Wood Industry Co., Ltd.; 2. Guangxi State-owned Paiyangshan Forest Farm; 3. Guangxi State-owned Sanmenjiang Forest Farm, Liuzhou, Guangxi 545006

Source: China Wood-Based Panels, Issue 3, 2019