Testing a New Separation Device for Sorting Recycled Plastic Chips Based on Differences in Specific Gravity

Approximately 9 billion kilograms of plastic are used to produce durable goods each year in the United States, but only 2% of this plastic is recycled today. A major obstacle to recycling plastics from durable goods is that the densities of different plastics are often very similar, requiring a highly accurate sorting technique based on differences in specific gravity. There are many techniques currently available for separating plastics based on differences in specific gravity, but none of them are ideal for plastics recycling. A device called a hydrocyclone has a very high throughput rate, but it can only produce highly accurate density separations if the particles being sorted are very small (<?6 mm nominal size) and have approximately the same shape. MBA Polymers has developed the concept for a new device that can accurately sort larger chips ( approximately 12 mm nominal size and possibly greater) of various shapes. The shape of the proposed device is theoretically ideal for sorting particles based on differences in specific gravity. The objective of this Phase I project is to measure the separation effectiveness of this device using plastic chips of varying sizes and shapes. Separation effectiveness will be determined by generating standard ¿partition curves,¿ which can be compared with similar data that exist for other equipment. If successful, this device would make all streams of plastic from durable goods more economical to recycle.