Multi-step production of a product with high calorific value - premium SRF (solid recovered fuel) for energy recovery - from muniucipal, commercial and industrial waste.
The process starts with untreated waste from households, commerce and industries being fed – often via wheel loaders, diggers or dosing conveyors – into the primary shredder. The aim is to obtain homogeneous, sortable material ready for the next step in the process.
MAGNETIC SEPARATION OF FERROUS METALS
In the second step, a magnet fitted above the conveyor belt is used to securely extract ferromagnetic parts such as scrap iron and other ferrous scrap metal. Ferrous scrap metal in premium solid recovered fuels is said to spoil its quality. Once separated, it can be recycled in line with the circular economy concept.
In the third step, the pre-shredded material – now free from any ferrous metals – arrives in a continuous stream of material. The fine particles that are undesirable in SRF but that are often found in the input material are screened at this point. The screening technology can be selected and matched to your exact requirements. Common equipment includes drum screens, strainers, vibrating screens or disc screens. Depending on your requirements, it is possible to extract different fractions in this process stage such as fines of <10 mm and oversized fractions to obtain high-quality, medium-particle solid recovered fuel.
HEAVY FRACTION SEPARATION
Heavy fractions might cause increased wear or stand still in the secondary shredding process, that is the reason why such fractions are sorted out. The material stream is fed continuously into a separator where it is hit with an air current while it is in free fall. In this way, light materials are transported by air to the conveyor belt, whereas heavy materials fall to the ground to be discharged. Thanks to the circulating air, hardly any fresh air is needed.
SECONDARY (FINE) SHREDDING/GRANULATION
In the final stage of the process, the material is shredded a second time in a process called fine shredding or granulation. The material that is now free from foreign matter, heavy fractions and ferrous metal and fed into one or more secondary shredders depending on the system’s throughput capacity. The output is then known as the final product or premium solid recovered fuel (SRF). Systems typically generate up to 40 tons of final SRF per hour – and that 24 hours a day.
Solid Recovered Fuels (SRF) are mostly used in the main burners of rotary kilns and are categorised as solid alternative fuels. The main burner needs fuels that are easily flammable and burn in a way that high material temperatures can be achieved in the kiln’s sintering zone; these are necessary to form the desired clinker minerals (approx. 1,450 °C). For that to happen, the flame has to reach an operation temperature of approx. 2,000 °C. It is therefore vital that the SRF is composed of particles that have been cut perfectly.
The SRF must be free of foreign matter (e.g. metals, stones or glass) which might cause feeding problems or issues with the clinker quality. With perfectly coordinated processes, Linder high-end primary and secondary shredders, and double extraction of foreign matter, extremely reliable and robust SRF processing with minimum maintenance is guaranteed. Featuring some of the highest throughput rates on the market and ideal output quality, Lindner’s machines also boast surprisingly low energy consumption.
Efficient production of RDF for incineration with energy recovery in cement kilns/calciners or as fluidised bed.
In one-step shredding, the focus is on the shredder as a single-step solution. Untreated waste from households, commerce and industries is mostly fed into the primary shredder directly via wheel loaders, diggers or dosing hoppers with the aim of obtaining homogeneous, sortable material in a single step.
The shredded material continuously trickles out of the base of the shredder. A stationary conveyor belt is conveniently located immediately underneath to transport the product. The ideal choice here is a profiled conveyor belt operated by the Lindner Shredder or the control room.
MAGNETIC SEPARATION OF FERROUS METALS
Optionally, a permanent magnet can be fitted above the conveyor belt to securely extract ferromagnetic parts such as scrap iron and other ferrous scrap metal. Ferrous scrap metal in premium solid recovered fuels is said to spoil its quality. Once separated, it can be recycled in line with the circular economy concept.
If you want efficient plants for turning municipal, commercial and industrial waste into fuel, you first have to define the end product. Especially in the single-stage production of fluidised bed fractions for incineration with energy recovery in cement-kilns/calciners, it is vital that the shredding systems work extremely robustly and reliably – and mostly around the clock. The calcinator accepts lower-grade fuels with regard to particle size and calorific value. Unlike in the rotary kiln’s sintering zone, much lower material temperatures (approx. 800–900 °C) are necessary as the CO2 simply needs to be extracted from the lime.
A wide range of RDFs can be used depending on the calcinator type. With certain calcinators it is even possible to use entire tyres as fuel; however, most standard calcinators (e.g. inline, separate line and combustion chamber) use shredded refuse-derived fuels. Since there is a wide range of calcinator technologies and types, this table only serves as a guideline.MATERIALS:
Efficient recycling of post-consumer plastics
Shredding is an essential step in a smooth-running process chain. Untreated plastic waste either in baled or loose form is fed into the machine with wheel loaders or a conveyor belt.
The output is consistent, the cut precise and 90% of the output will be smaller than 60 mm with an output of up to 5 metric tons per hour.
PREWASHING AND FOREIGN MATTER SEPARATION
The requirements for prewashing are clearly defined. Pre-shredded plastics are often heavily contaminated and loaded with foreign matter. The rafter’s well-engineered technology effectively separates abrasive matter and prepares the material for all following processes.
Now free from foreign matter, the material is granulated using a wet granulator that screens the material to the preferred particle size to make recycling particularly efficient.
Categorising plastics according to their specific weight. This step is executed with Lindner Washtech’s gravitator, a machine that combines state-of-the-art features with the tried-and-tested sink-float method. In this process, not only is it important that the output material is homogeneous, but the machine’s construction must also be compact and efficient.
Efficient washing through friction. The Lindner Washtech friction washers clean even the smallest particles very effectively. The machine size can be adjusted to the customer’s specific throughput requirements, achieving rates of up to 4 metric tons per hour. The machine’s screens and paddles are also customisable.
MECHANICAL AND THERMAL DRYING
The shredded and washed material is fed into a centrifuge where the plastic flakes are dried in controlled conditions. The resulting centrifugal forces contribute to cleaning and drying the materials. Finally, the material is thermally dried and can subsequently be transferred for extrusion.
Post-consumer waste is created by consumers, e.g. individuals and households. While in the past plastic waste used to be incinerated, these days it is considered an important raw material. To utilise post-consumer plastics, the aforementioned process is necessary. For recycling purposes, the material must be as clean as possible to prevent damage to machines and pre-empt inferior-quality products.
Lindner relies on tried-and-tested technology to guarantee high-quality material. The field of post-consumer plastics in particular demands high machine standards since the material might not only contain abrasive matter but also food scraps. The foreign object-resistant shredder and the high-end washing technology solution ensure a homogeneous product ready for extrusion. Manufacturing companies can then turn the resulting lenticular plastic raw materials into the final product.MATERIALS:
Efficient production, targeted recycling
In this step, the material is fed into the machine via a conveyor belt. Materials can be supplied to the conveyor belt via a wheel loader or a forklift. To facilitate continuous feeding, our shredders permanently communicate with the conveyor belt and subsequent processes such as granulators or extruders. The metal detection system directly connected to the system control protects subsequent processes. This is necessary to guard the granulator, which is sensitive to foreign matter, and to prevent the high costs caused by downtime.
In the second step, the visually inspected material is shredded. The robust Lindner shredder splits the material into the right output size for subsequent processes. To achieve the best possible throughput the shredder, conveyor and granulator continuously communicate and control the speed and the amount processed.
The material coming from the foreign matter-resistant shredder is fed into the granulator and processed to the required particle form. Rotor speeds of 600 rpm are normal in this process. Due to the high speed, it is necessary for the material to be as perfectly prepared as possible to avoid the granulator malfunctioning.
In this step, the material that has been processed by the granulator to a particle size of 8–10 mm is sucked into containers like big bags or directly transported for further processing.
In-house recycling for efficient production processes – plastics and other production waste are important raw materials in the manufacturing of plastic products. Linder shredders were developed with precisely these requirements in mind. Thanks to an adjustable cutting gap and variable screens, you can customise the particle size to the needs of your subsequent processes.
Our primary shredders are resistant to foreign objects and are able to shred hard, rigid plastics to a particle size of <10 mm, as is necessary for recycling purposes. Since the material is often bulky and slightly contaminated, it is not possible to feed the material directly into the granulator. That’s were the primary shredder comes in, splitting the materials to protect the granulator or extruder and minimise the costs of downtime.
Recycling waste wood plays an important part in environmental protection. Particularly clean waste wood can be recycled and reused as a new product (e.g. recycled chipboard).
After the wood has been sorted in accordance with the waste wood grades, A1 and A2 waste wood is processed in the first shredder. This slow-speed shredding system shreds pallets, chipboard, demolition and other partially bulky wooden parts with the aim of creating homogenous, well-broken-down material to subsequently separate nails and other metal parts from the material.
MAGNETIC SEPARATION OF FERROUS METALS
In the second step, a permanent magnet fitted above the conveyor belt is used to safely extract ferromagnetic parts such as nails, scrap iron and other scrap metals.
SECONDARY (FINE) SHREDDING | GRANULATION
The pre-shredded waste wood that is free from foreign particles and metals then enters the second shredding stage. The final product should be homogenous and about 15–30 mm in size to ensure that the recycled material is of high quality throughout for the production of chipboard later on.
Recycling renewable resources such as wood plays an important part in environmental protection. Wood is often used for pallets, chipboard and demolition wood, etc. At the end of its life large quantities of it end up as waste wood on recycling companies‘ premises. Then particularly clean waste wood can be recycled and reused as a new product (e.g. recycled chipboard).
Particularly when recycling waste wood, it must be processed in several stages – mostly including these steps:
Waste wood is turned into valuable fuel to generate heat and electricity. The recycling process is kept as lean as possible to fuel the power plant with material that has the lowest costs per ton.
The waste wood is collected in large quantities at the recycling company’s premises and mostly fed directly into the shredder with a wheel loader or a digger. The digger operator first separates the metals etc. during the feeding process. The water spraying system on the shredder makes sure that there is none of the air-born dust usually found while processing wood. The aim here is to shred the material to previously defined output sizes ranging from 80 to 120 mm.
MAGNETIC SEPARATION OF FERROUS METALS
The magnetic separator fitted above the discharge conveyor safely extracts ferromagnetic parts such as nails, metal plates and hinges.
After shredding, the final particles are further classified. A defined particle size of usually <80 mm, <120 mm or according to the class in line with EN ISO 17225-1 are required for incineration in combined heat and power plants.
RETURNING OVERSIZED PARTICLES
Thanks to an integrated system, the screened out oversized particles are returned to the shredder. This eliminates the need to transport the material back into the shredder with a wheel loader.
Energy recovery from waste wood in large biomass power plants has become very popular and is often the only way to recycle large quantities of waste wood in the grades A1–A4, ranging from pallets to old railway sleepers.
This allows waste wood to be turned into valuable fuel to generate heat and electricity. The recycling process is kept as lean as possible to fuel the power plant with material that has the lowest costs per ton.
The shredder is key to paper recycling. Depending on the feed, grain sizes of 90% smaller than 20 mm and a throughput of up to 5 metric tons per hour are possible. Thanks to the precise cutting sequence, even data destruction standards can be complied with.
The suction hood fitted to the processing machine and discharge ensures clean air and minimises fire risks by transferring even the smallest air-borne particles to the filter.
In this step, the dust captured in the suction process is filtered to ensure a safe and low-particle environment.
Conveying technology suited to the machine’s design and processing speed offers the best transport of materials to and from the machine. Thanks to integrated controls, it is not necessary to operate the conveyor belts separately. Lindner’s smart control concept regulates the speed automatically, thus guaranteeing maximum output.
MAGNETIC SEPARATION OF FERROUS MATERIAL
With our Lindner shredder that is resistant to foreign matter, whole bales or even contaminated materials can be processed. A large over-belt magnet separates metallic parts at the end of the conveyor line, reliably removing scrap metal such as binding wires and other foreign objects.
Sophisticated, superior shredding solutions are paramount for defined grain sizes. When it comes to data security, Lindner can build on our years of experience in shredding technology. With our superb technology and tried-and-tested machines, we shred data carriers such as paper, DVDs and magnetic storage media up to security level 5 of the DIN66399.
We repeatedly conduct tests that are certified to guarantee premium data destruction for our customers. The environmental considerations are also a huge priority for us: the shredded material can be prepared for recycling and turned into new products.
Metals are precious raw materials that can be recycled and formed into new products almost endlesslySHREDDING
MAGNETIC SEPARATION OF FERROUS METALS
Especially while processing metal profiles or metal frames, over-belt magnets can easily sort out ferrous metals. With this step, higher quality, homogeneous fractions can be achieved (e.g. aluminium scrap).
PRIMARY SHREDDING WITH INTELLIGENT ENERGY MANAGEMENT
Specialists, get ready: Lindner believes in the future of electric drives in shredder technology and has identified a clear trend in solid recovered fuels production. At IFAT 2018, that took place in Munich from May 14th to 18th, the technology leader with 70 years of engineering expertise introduced the Lindner Atlas. This stationary ‘ripping’ twin-shaft primary shredder perfectly complements the tried-and-tested Jupiter series: the newly developed ripping system ensures very high throughputs and little downtime: it is (cost)-efficient, energy saving, environmentally friendly and produces little noise.
Optical sorting systems, such as those following primary shredders in modern SRF lines, can sort out recyclables more effectively and thus better comply with legal regulations and requirements if the discharge conveyor is evenly filled with material. Furthermore, coarser particles are often an advantage. Film, for example, should be the size of an A4 sheet.
In response to greater demands on recycling sorting processes and the growing need for coarser output in SRF production, Linder has developed the Atlas: the ideal primary shredder complemented by the outstanding secondary shredders of the Komet series.
With the new Atlas twin-shaft shredder (a slow-speed, high torque solution), both shafts of the shredding unit can rotate independently while featuring a particularly sturdy frame: perfect for asynchronous and synchronous operation. If one of the two shafts stops due to foreign objects, bulky or tough input materials, the second shaft can still be used in asynchronous operation, ensuring continuous and uniform material discharge. As Lindner Product Manager Stefan Scheiflinger-Ehrenwerth explains, shredding takes place in both directions, enabling a peak throughput of 40 to 50 metric tonnes per hour depending on the input material – even in reverse mode. The robust machine also does not require a pusher/ram: the shafts powerfully pull in material.
Optical sorting systems can then recognise and separate significantly more recyclables from the coarsely pre-shredded, evenly discharged material and take it out of the material flow. The Atlas provides the perfect output for sorting technologies and thus the best possible dosage for secondary shredding.
What makes the Atlas shredder so unique and innovative – asynchronous, ripping shaft systems have long been available on the market – is the machine’s electric drive concept. Lindner, as a leader in shredding technology, further developed its well-established asynchronous motor belt drive and is now introducing a first: a twin-shaft shredder with intelligent energy management. Stefan Scheiflinger-Ehrenwerth enthuses when describing the company’s latest development: ‘As a result, the machine consumes up to 40% less energy than shredders with conventional hydraulic drives and has even faster reaction times.’ What is more, a container for the oil tank is no longer required: ‘A hydraulic power pack as large as the machine itself is no longer needed.’ Compactly built, the Atlas takes up little space in the client’s facilities.