Process removes volatile organic compounds

Depolymerization. Carbios, Saint-Beauzire, France, has developed a new approach to treat polyethylene terephthalate (PET). In a newly published U.S. patent application, the company describes using a microorganism that excretes a chemical or enzyme to depolymerize PET and other plastics. The approach could be used to depolymerize PET products that contain other polymers that are not easily extracted, such as a bottle’s polyamide layer.

Patent application 20170114205; published April 27

Solid refuse fuel pelletizing. A South Korean inventor has patented a system to pelletize scrap plastics while conserving water. It is especially geared toward thermoplastics.

Suook Young Park’s setup uses a pair of crushing screws to homogenize plastic scrap from agricultural, domestic and industrial applications. Screw conveyors, a vibration sieve-plate conveyor and filter units are used to remove impurities, such as metals, from the scrap and to fuse the plastic before it enters an extruder, where it is turned into pellets.

Because the water and scrap do not come into contact, the invention does not use as much water as other scrap-to-pellet systems. Competing processes often use washing tanks, which consume large amounts of water and add moisture to recycled pellets, reducing their value and necessitating the use of dryers. By comparison, the patent claims the invention is less expensive and more environmentally friendly.

Patent 9,662,808; published May 30

Separation. Veolia Environnement, Paris, has proposed a vision and sorting system to separate materials heaped in a bin or pile. The technology is intended to replace manual sorting.

As part of the process, electromagnetic radiation sensors—visible spectrum cameras are preferred—scan piles of mixed refuse. Using images from the sensors, an operator selects objects for an associated robot to grab. Alternatively, the sorting system can include image processing and calculating software to aid in identifying objects the robot should pick.

Patent 9,682,406; published June 20

Shredding. A shredder rotor assembly that has been patented by Republic Machine Inc., Louisville, Kentucky, features a bolted-in cutting apparatus. Designed to withstand repeated contact with metal contaminants, the invention is an alternative to rotor devices that use welded blade holders in combination with bolted blades.

Patent 9,687,855; published June 27

Removing volatiles. Compagnie Plastic Omnium, Levallois-Perret, France, has devised a way to treat postconsumer scrap so it can be recycled and used to make coated parts requiring good appearance qualities.

Using a wetting agent and an agent for solubilizing fatty acid esters, the company claims it can remove volatile organic compounds. Treatment with the agents occurs after the sorting, grinding, separating, washing and drying steps.

After applying heat to the solution at temperatures below its boiling point, the plastic softens. The wetting agent reduces the extraction solution’s surface tension, and the acidic solubilizing agent allows fatty acid esters to dissolve in the solution.

In a variation dealing generally with polyolefins, the process requires using aliphatic alcohol with an alcohol content of between 4 percent and 25 percent by volume as the wetting agent and an acid with a pH of between 2 and 5 as the solubilizing agent.

“This type of method reduces in polymers obtained from ‘postconsumer’ materials the presence of pollutants, such as volatile organic compounds, which the inventors have seen to cause appearance faults in parts manufactured from these polymers,” the patent says.

Patent 9,688,833; published June 27

Recyclate verification. International Business Machines (IBM) Corp., Armonk, New York, has patented a process for verifying recycled plastics’ composition. IBM proposes adding a predetermined amount of one or more verification compounds, or indicators, to a base resin.

“The indicator is thermally stable at the melt temperature of the resin but can be removed (thermally or otherwise) at higher temperature provided that the higher temperature is still below the decomposition temperature of the resin,” the patent states.

Patent 9,708,463; published July 18