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In recent years we have seen a sharp increase in the number of waste fires in Europe. Research has shown that the main causes of these fires are heating and the presence of flammable substances. The latter category includes batteries, the cause of 49 of the 53 fires at European companies in the electronic appliances recycling sector. These fires result in the release of hazardous substances, which can also affect many local residents. Apart from all the immediate risks, we lose valuable metals like cobalt when batteries go up in smoke, enough reason for Team CORE to solve the problem.
The main problem with batteries is that they can become unstable due to various causes, potentially resulting in spontaneous ignition. Because a battery also contains a lot of oxygen, the fire is almost impossible to extinguish; this phenomenon is also known as thermal runaway. Apart from this, parts of the battery can also be ejected due to the pressure build-up, damaging other batteries in storage. This problem is particularly troublesome in the recycling of electronic products, where the batteries are well packaged, such as Bluetooth music speakers.
But battery fires also play a big role in other industries. In the metal industry it is the number one cause of fires. In paper recycling companies it even ranks third. According to the Ministry of Infrastructure and the Environment, the reason for this can be found in the low percentage of batteries collected. Only 24% of lithium-ion batteries in the Netherlands are collected, the rest end up among the PMD waste, residual waste and waste paper.
There are various types of electronic waste currently in circulation. Some of these contain a battery, which, for portable devices, are mainly lithium-ion. Our technology aims to process such devices, rendering them safe and preventing hazardous situations in which the battery catches fire, emits toxic smoke and endangers both the company recycling the waste as well as the surrounding area.
Our machine, CORE TITAN, accomplishes this through a combination of submerged shredding. A shredder is a device containing a number of blades. These blades pull any material that reaches them in, cutting it into smaller pieces. This allows for separation into different fundamental materials – in the case of batteries, these are metals like cobalt and lithium, plastics, and salts. If lithium-ion batteries were shred in air, the damage would result in immediate thermal runaway.
By instead submerging the shredder in water, we can prevent this from occurring. This is possible because of two aspects. First, the water contains a solution of salts. These salts are conductive, so that the battery is rapidly discharged. Second, any heat produced during shredding is absorbed by the water. Water has a high thermal capacity, limiting the potential increase in temperature to only a few degrees. These two effects combine to create a safe environment for lithium-ion cell processing.
The shredder consists of a number of parts. It is driven by a 7.5 kW electromotor, rotating at 1500 RPM. Through a gearbox, this is reduced to 60 RPM, strongly increasing the torque. A series of water-tight bearings transfer it to the box containing the blades of the shredder. Batteries are introduced through the top, being pushed down by a perforated plate into the blades. There, they are quickly dismantled and cut up, and accumulate together with water below. After processing is complete and no more parts are visible at the top, the shredder is drained into a storage tank through a valve.
We have tested various combinations of batteries and products containing batteries, at different levels of charge. These tests were successful, resulting in an inert stream of metals, plastics, and dissolved salts. Samples taken during are currently being analysed in cooperation with Eindhoven University of Technology and Fontys.
Following this processing step, CORE has continued to research further processing steps. The inert stream from the shredder can be further separated, removing plastics, printed circuit boards, wires, rubber, battery parts etc. For this, we are cooperating with different industrial partners active in the recycling industry, to enhance and accelerate the development and application of these techniques.
|Processing capacity||100 per minute|
|Shift||1500 -> 60 RPM|