5.1.2 What is Recycling?
Module 5: Recycle
Here you will find a short overview about the current Recycling process. We tried to break it down into 10 easy steps. Of course, the process can be discussed in greater detail, but these 10 steps are the important ones.
The next video will convey a lot of information. We have tried to make it as interesting as possible and as detailed as necessary. Do not worry if you don’t understand something right away. After the video, you will find a text with all the information.
1: Transportation of the product
First of all, the product must be transported to the recycling plant, where the product and its constituent materials, can be managed. This will generate costs in energy.
2: Extract the parts which can be reused
In this step the product will be checked for well-functioning parts. If these parts are easy to dismantle from the main product, then they can fulfill their designated task in either a similar or a different product. In the case where they no longer work as needed they can be remanufactured. But, remember, this will only be done if it is profitable to dismantle this single part from the main product. Depending on the part, and its connections to the main product, this step will provide more or less value in the process. The easier it is to remove these working components, and the higher their value of the part in the overall product, the higher the chances they will actually be removed and reused or remanufactured.
3: Separate those parts which are already in a decent quality
If possible, you can pick out the single parts that are easy to dismantle, and feed them into the appropriate process to manufacture new products out of them. These parts could be, for example, housings and casings made out of plastic or aluminum, pure copper wires, or steel parts such as screws which are only used to connect other components together.
If these parts are excluded from the rest of the process it will not only retain a lot of the component’s value, and save money in the remanufacturing process, it will also help the downstream processes.
4: Feed the rest into the deeper recycling process
The residual parts of the product, the ones which are not easy to reuse or remanufacture as they are, will now be fed into the recycling process. The aim of this process is to separate, or liberate, as many different materials as possible. At this point all these materials are still joined or linked to each other, and a lot of energy will be needed to break these connections.
5: Shred everything
In most cases the material will now be shredded. This will reduce the size of the parts, will hopefully break the joints, and will therefore separate the materials from each other. This operation is crucial for the steps that follow. Occasionally this process will connect different materials through bending or pressing. Some material connections are so complex that it will not be possible to separate them in one step.
Classifying the output of the shredder is necessary, it will divide this output into a material mix which can be processed during the sorting phase that follows. Mostly, the output is classified by particle size. At the end of the process there will be at least two different classes, which are distinguished in at least one dimension.
Each class now needs to be sorted. This could happen by density, with a magnetic or electric field, or by using other physical or mechanical characteristics of the material we want to separate. The chosen mechanism depends on the material mix. Ferrous materials are easy to separate from aluminium by using a magnetic field. But if we are trying to separate aluminium from a mix of polymers, then a magnetic field is not the right mechanism to choose.
8: Extract suitable materials out of the process
In this stage of the process we could separate materials which fulfil all the requirements of a certain manufacturing process. These materials can therefore be fed into a new production process. At this point in the process, a lot of effort and energy has already gone into extracting these materials. Depending on which material we are extracting this process might be economically justifiable, or not. Materials which are lower cost to obtain from primary sources, for example through mining, makes the recycling process less valuable, as the price of the recycled material is already relatively low. For materials which are precious, rarely found on earth, or simply hard to access in their primary source, we can justify putting even more effort into the recycling process, as these materials have more value.
9: Restart this process, from step five, for as long as it is economically feasible
In many cases the high value of the materials will justify additional recycling effort. With every repetition of steps five to eight, the particles will become smaller and smaller. In most cases, the separation of smaller parts requires a different machine from the one used before. In all cases, the cost of each repetition will add up to the total price of the recycled material. Certain processes will be more expensive, due to the fact that more and more complex machines and processes are needed to sort and separate the shredded materials.
10: Burn or dispose of the rest
In the end, material mixes that do not carry enough value to justify further processing will be either burnt or transported to a landfill. In case of incineration, there may be some energy generated out of the process, but materials that end up in a landfill are unlikely to be used again. These materials will most likely stay there for a very long time. These materials are therefore lost, unless it someday becomes economically feasible to dig them out and re-process them. Both incineration or landfilling is something we, as designers and engineers, must truly try to avoid.
Engineering Design for Circular Economy by TU Delft OpenCourseWare is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Based on a work at https://online-learning.tudelft.nl/courses/engineering-design-circular-economy/.