Hydraulic, mechanical, roller presses… How to make the difference?


In an economic and social context where ecology and the circular economy are increasingly present, many companies are faced with a new problem: what to do with their production by-products? Since the “trash” solution is not the best one, both from an environmental and economic point of view, companies are turning more and more to alternative solutions, allowing them to save money by recycling their fines into recovered and recyclable products in the production process while minimizing their impact on the environment.

A new question arises: which solution will I choose and which one will be the most adapted to my needs? Indeed, the solutions are numerous: hydraulic, mechanical, die, roller press, rotary presses, extrusion technology or pelletizing by compaction, it is easy to get lost when you are not a great expert on the subject. Especially when you know that each of these major technologies can be divided into several ranges of different equipment…

In order to make it understandable, here are the main concepts of each of these technologies.


This press technology can meet a wide variety of application needs, as it can process lime, steel-mill by-products, coal, charcoal, coke, refractory clays, DMT, maleic anhydride, premix, glass mixtures and many others.

Of course, the feed materials must meet certain requirements. For example, to be suitable for agglomeration, the materials must be 100% or predominantly inorganic, relatively small in terms of grain size (less than 10mm for large briquettes, less than 3mm for smaller ones), relatively dry (less than 1 or 2% moisture content) to avoid clogging, tolerate the addition of binders or lubricants, and be able to support the overall costs of briquetting.

A roller press consists of various parts including a feeding system, a support frame, two sets of moulding rolls, a hydraulic system, a drive unit and control or lubrication devices.

The feeding of the raw material to the press rolls can be done in two different ways: by gravity feed or by forced feed.


But then, how to choose the type of feeding? Very often, the choice will be induced by the nature of the raw material to be agglomerated: the finest raw materials and applications without binder will more particularly require a forced feed, while coarser materials or those requiring the addition of a binder will mainly require a gravity feed.

Gravity feeding is the simplest technique and the first to emerge. It is generally used for applications with low pressure binders fed to a wide roll. In other cases, it may also be necessary to process materials that may stick to the feed screw or become sticky during the pre-compaction stage. This technology offers many advantages: the system is simple and minimizes contact between the raw materials and possible moving parts, reducing their premature wear and tear; the risk of clogging during agglomeration of wet mixtures is lower than with other feeding systems and finally it allows a reduction of investments (CAPEX).

The forced feeding of the material to the rolls comes in different forms: vertical or horizontal. They differ according to the use of different types of screws: single or double screws and conical or cylindrical screws. The choice is part of our expertise and we will be happy to discuss with you the optimization of the feeding according to the raw materials involved.

After passing through the feeding stage, the processed raw material then arrives at the press rolls. The roll assemblies of a roller press consist of a fixed roll associated with a movable (floating) roll, the two being held together by the action of hydraulic cylinders. Each assembly consists of a shaft, one or two tyres, two housings with roller bearings and seals, and finally a half coupling for the connection of the main gearbox.

The compaction force is expressed in linear kN/cm in the roller press technology.

Of course, this force depends on the type of raw material being processed and whether or not a binding agent is used, which will at the same time affect the mechanical design of the press.

Generally speaking, the hydraulic circuit of a roller press includes 2 or 4 hydraulic cylinders; 1, 2 or 4 nitrogen accumulators as well as a pump motor associated with the instruments necessary for measurement and safety: press sensors, solenoid valves, pressure limiters, oil filters….

briqueting with a roller press


This briquetting technology mainly concerns two types of raw materials: biomass such as wood, hemp, hay, flax, miscanthus, straw, paper, peat… and metals such as steel, aluminium, bronze, copper, cast iron, brass, grinding sludge…

This process is based on a simple operation: the raw material is loaded into a feed hopper and is then transported via a screw conveyor to a pre-compaction chamber.

The pre-compactor then compresses the raw material to the main chamber where a piston pushes the raw material through the pressing mould to form the final briquette.

Ejectors that are positioned parallel on either side of the main piston then eject the briquette alternately through either ejector while another briquette is being formed.

Briquetting processes using hydraulic press technology offer significant advantages such as high specific pressures, ease of operation, automatic 24/7 presses, low operating costs, low power consumption, low wearing, quick installation and integration into the production line, small space requirements, reduced storage and logistics costs and recyclable metal briquettes in the remelting process.

Technologie de briquetage hydraulique


The raw materials concerned by the technology of mechanical presses are wood (wood chips, logs, sawdust, MDF, torrefied wood, demolition wood, hardwood …) and agricultural residues (peanut shells, corn stalks, rice shells, coffee shells, miscanthus, bagasse, cotton stalks …).

Mechanical press technology is based on the principle of a constantly rotating eccentric which is connected to a press piston that compresses the raw material in a conical compression die. The use of mechanical presses makes it possible to produce briquettes for industrial use in industrial furnaces as well as log type briquettes for domestic use for combustion in fireplaces, wood stoves or inserts.

In order to optimize the briquetting process and to obtain briquettes that meet expectations at the press exit, the raw material fed must meet certain requirements: it must be homogeneous and have a moisture content of between 8 and 14%. It must also have an appropriate grain size and an ash content of less than 0.5%, otherwise the abrasiveness of the material will cause premature wear of the parts in contact.

The use of a mechanical briquetting system also offers many advantages such as the recovery of raw material fines, the reduction of residue volumes, savings on logistics, storage and landfill costs, the production of briquettes for industrial use or for the consumer market, and the use of technologies that can be used on many wood and biomass materials.

Technologie de briquetage mécanique


Die presses are equipment used in the manufacture of high-density pellets, this technology is also called “pelletizing” (pellet presses). This process is based on a simple operation: the raw material fed into the press is compressed through the die by the action of rollers.

The raw materials that can be processed by the die press technology are mainly organic raw materials such as products for animal feed, biomass (wood, vegetable waste…), organic and organo-mineral fertilizers, plastic additives, dried urban sludge…



Rotary press technology is used in the manufacture of tablets or pellets from powders. This type of process is done in a cold, binder-free process and consists of placing the raw material in a mold and compressing it between two punches. (inferior and superior)

The applications of the tablet shape mainly cover organic powders (agriculture and food industry) and mineral powders (detergency, disinfection, linen care, swimming pool treatment, industrial additives…).

However, this technology is more limited in flow rate than the roller presses and generally requires more CAPEX and OPEX for a given flow rate.

There are many briquetting solutions currently available on the agglomeration market. This diversity allows potential customers to find the technology that best suits their raw materials and their expectations in terms of finished products for many industries.



Euragglo S.A.S. is a member of the Köppern Group and represents RUF Briquetting Systems and C.F. Nielsen A/S in the French market. This enables Euragglo S.A.S. to offer the most complete range of briquetting and granulation equipment.

In order to define the best solution to meet your needs, Euragglo offers you to test your raw materials in its facilities in order to identify your needs and to recommend the most suitable equipment.

Do not hesitate to contact us by phone 03 27 09 00 09 or by email euragglo@euragglo.com for more information.