THE METAL RECYCLING CIRCLE
Metals can be recycled repeatedly. After the initial extraction of raw materials, they can enter an almost endless recycling circle. This begins with the production of long and short-lived goods, such as automobiles, machinery, technical products, construction needs, or consumer goods. These are distributed to the respective consumers and only at the end of their product life cycle, possibly after a period of repair and reutilization, enter recycling. However, some of the metals used become waste products in the production process, such as chips and grinding sludges. These can be processed and directly introduced into recycling.
Since metals are used in a wide range of industrial and household goods, their processing and reuse are particularly important from both economic and ecological perspectives. Without a functioning metal recycling system, there would be a scarcity of resources and significant price increases. Moreover, primary raw material extraction has serious implications for soil, air, water, and biodiversity. Also, for the sake of emissions reduction and energy conservation, a circular economy should be pursued. For instance, using secondary aluminum compared to primary aluminum reduces CO2 emissions by over 90%, as well as energy consumption.
The supply of the EU with metals is already mostly based on secondary raw materials. However, forecasts suggest an increased demand in the coming decades. Therefore, recycled or prepared-for-recycling metal is expected to gain even more value.
WHERE DOES THE BRIQUETTE PRESS COME INTO PLAY?
Every metalworking company can contribute to a functioning metal recycling circle. In industries where metal chips and metal grinding sludges are regularly generated in the production process, this contribution can be made through the use of a hydraulic briquette press.
With such a system, chips are separated from coolants in the pressing process and compacted into highly compressed, manageable briquettes. As a consequence, the processed chips become valuable secondary raw materials. The hydraulic press system can dewater and briquette both (wet) metal chips and metal grinding sludges (a mixture of fine metal chips, abrasive abrasion, coolant, and other impurities). This treatment is particularly essential for grinding sludges, as otherwise the valuable components must be disposed of as hazardous waste (according to the EU waste catalog).
Therefore, the investment is worthwhile in all industries generating such “waste products.” These include, for instance, the automotive industry, aviation industry, machine tool industry, and similar metalworking industries.
THE OPERATION OF BRIQUETTE PRESSES FOR METAL CHIPS
But how does such a press work precisely? Below, we explain the structure and operation of briquette presses (or briquetting presses) using our briquette press type WSPK as an example. The operation of a briquetter may naturally differ depending on the manufacturer and the specific application. Furthermore, our presses are individually tailored to the project requirements.
At the beginning, waste materials are fed into the dosing bunker with a screw conveyor(1) through a feeding unit. This conveyor transports the material into the pre-compression unit(2). This pre-compression unit compresses the material into the pre-press bushing and initially stops there. Now the main pressing process takes place: The main pressing cylinder(3) extends and compresses the material under high pressure in the press bushing(4) into a solid briquette.
Subsequently, the main pressing cylinder relaxes and stops. A counter piston moves downward and opens the discharge channel. Simultaneously, the pre-compression unit is raised again. The main pressing cylinder pushes the briquette out and inserts it into the discharge channel(6). The pressed oil is collected in a collecting pan(7). Then the process begins anew: The main pressing cylinder retracts, and the dosing screw refills the pre-compression unit.
The position of the pressing piston is detected by the displacement measuring system, whereas the position of the pre-compression unit and the counter piston are detected by limit switches. The releases for the extension and retraction of the cylinders are given according to the cylinder positions. The displacement measuring system also adjusts the briquette length. If the briquette is, for example, shorter than specified, more chips are fed through the dosing screw in the next pressing process. Therefore, the filling volume in the pre-compression unit is constantly regulated, and the briquette length is automatically adjusted.
DO YOU WANT TO RECYCLE YOUR METAL CHIPS?
Learn more about the operation of our FAUDI briquette presses for metal briquetting here.
BENEFITS OF USING A BRIQUETTE PRESS FOR METAL
Using a briquette press is economically beneficial for companies in various ways. Firstly, the briquetted metals can be returned to their own production cycle or sold to recyclers for higher returns. Revenues from the sale of metal chips are already a fixed part of the budget of many companies, especially since the amount of scrap generated is already calculated in production.
Secondly, costs are reduced in various areas. A significant factor is the recovery of expensive coolants from dripping metal chips and metal grinding sludges. This significantly reduces the need for fresh coolants. Moreover, due to the substantial volume reduction, there are lower transport and storage costs.
Environmental benefits should not be underestimated.
Coolants are returned to the cycle not only for economic reasons but also for ecological ones, and this reintegration is gaining importance within the framework of necessary environmental certifications. Using the press also prevents metal grinding sludges from being disposed of as “hazardous waste” in specialized waste landfills or incineration facilities, which can be cost-intensive. The responsibility for proper disposal lies with the producer. From both ecological and economic perspectives, recycling with a briquette press is the better solution.
For a concrete insight into the profitability of briquetters, we will look at two example calculations.
When used as a grinding sludge press and with a quantity of approximately 500 tons per year at 50% residual oil content, an oil saving of about 228 tons is expected. This results in savings of approximately €570,000 solely for reduced fresh oil requirements (at €2.50 per kilogram of oil), in addition to savings of approximately €50,000 in disposal costs and about €13,600 in briquette sales revenue. In this specific example, the cost savings are expected to be over €630,000. Similar dimensions apply when pressing aluminum with a residual oil content of 20% and a quantity of 1,000 tons per year. Here too, through savings on oil and additional revenue, a profit difference of +€480,000 can ultimately be expected.
COMBINED SOLUTIONS FOR GRINDING SLUDGE PROCESSING
However, grinding sludges remain a challenge in briquetting. The pressing performance depends on the content of liquid or residual moisture in the sludge due to the specific operation of briquette presses. The lower the residual moisture of the sludge, the higher the throughput performance of the grinding sludge press. To better process wet metal grinding sludges, the pre-installation of a screw press is worthwhile in some cases. This press can pre-dewater the grinding sludges and contribute to efficient briquetting. We have summarized how this works in a separate article on the operation of screw presses.
CONCLUSION ON THE OPERATION OF a BRIQUETTE PRESS
Establishing a closed recycling loop for metals is essential, both for economic and ecological reasons. Even within the production process of metalworking industries, metallic waste products can be introduced into metal recycling, which is also highly profitable for businesses. Hydraulic briquette presses work reliably and process both chips and grinding sludge efficiently, especially in combination with a pre-dewatering screw press.
If you also want to convert your metal chips into valuable materials, we are happy to advise you on the best solution for your specific application.