Hot Compactor


designs and manufactures hot compactor for heavy-duty operation under hard and difficult conditions, with reliable use and minimal maintenance. Compared to briquetting presses used for cold briquetting application, hot compactor is fitted with special dispositive to comply with the hot material:
  • Parts in contact with the product are manufactured from special refractory stainless steel.
  • Water cooling system installed on the heat-sensitive parts.
  • Seal gas system for injection in defined zone to avoid the DRI re-oxidation.
  • Powerful sub elements (rolls drive, force-feeder drive, rollers bearings, hydraulic system, press frame,…)
  • Equipment’s parts adapted to accept thermal dilatation.
  • Instruments design for high temperature and flammable resistant.
  • Additional instruments installed to control and protect the equipment.
  • Special surface treatment on the parts of the equipment.
Click on the different parts of this hot compactor to discover its main components:

Feeding system

The feeding system is essential for the hot compactor efficiency:


has developed a special double force-feeder with high feed bin volume equipped with two screws specially adapted for degasing and predensifying the hot DRI and feeding the rolls.

Made of special refractory stainless steel adapted to the high temperature, the force-feerder tank is also thermally insulted. A cooling water system is installed for the force-feeder tank and the screw shaft. Seal gas system is also injected in these parts to avoid re-oxidation of the DRI.

The force-feeder screw shafts are driven by variable speed gear-electric motors installed at the end of the screw shafts. Two frequency inverters installed in the MCC adjust permanently the speed of the screw shafts though a control loop design in the Control- Drive cabinet.

This feed system is also equipped with special floating cheek plates system reducing the powder leakage on the roll sides and providing a better efficiency in the densification area. In order to preserve the life time of the cheek plates, there is also internal water cooling.


Rolls surface

The hot compactor is composed of two rolls: one is fixed in the compactor frame (fixed roll) whereas the other roll can move perpendicularly to its axis (mobile roll) varying the space between them. The size of a hot compactor is characterized by the roll diameter (from 400 mm to 1440 mm) and the roll width (from 600 mm to 700 mm).

The technological solution for the working surface of the rolls is shafts with pocketed tyres fitted with cooling system. There is a special hardening treated material (special steel with thermal treatment…) used for the manufacture of the tyres dictated by the DRI abrasiveness, corrosive effect and the hot compacting conditions (product temperature, briquetting pressure).

Rolls bearings

These rolls are mounted on heavy-duty bearings sized for a long life-time, automatically lubricated by grease. The bearings are also water-cooled.


The hot compactor is composed of a steel frame machined and assembled with a sufficient mass for heavy-duty operation under high pressure.

With a hinged design, the frame installed on the hot compactor allows a quick replacement of rolls for maintenance purpose without dismantling the feed system and the components above the rolls.

Hydraulic System

The hot compactor is equipped with an hydraulic system able to apply a force on the mobile roll by means of jacks. This force can be different in certain cases on each bearing block of the mobile roll thanks to a double hydraulic circuit. This system also includes safety devices and nitrogen accumulators to dampen the movement and quick return of the mobile roll and protect the hot compactor when tramp material is inadvertently fed to the rolls.
The force applied on the product can be up to 180 KN/Lcm.

Rolls drive

The hot compactor is equipped with a special double-output gear-box and internal gear couplings able to withstand the axial misalignment caused by the mobile roll movement. The coupling of the mobile roll is fitted with a device for circumferential adjustment of the rolls that provides a perfect synchronisation of pockets between the fixed roll pockets and those of the mobile roll.

The rolls drive in ensured by main electrical motor mounted on a frame controlled through a variable frequency drive mounted in the MCC.

The tangential rolls speed can go up to approx. 0.6 m/s.


Considering the high temperature of the material and in order to protect the hot compactor, its main parts are protected by a cooling water system.

Fitted with networks pipes, a set of valves and instruments (temperature sensors, flowmeters, pressure switches), this cooling water system is designed to control and distribute water at required temperature and flow to each important parts of the hot compactor (force-feeder shaft and tanks, cheek plates, rolls shafts, rolls bearings,…)
Considering the presence of sparks during production caused by the high flammability of the DRI, and to avoid re-oxidation of the DRI, an inert gas (like nitrogen) must be injected in the hot compactor press to minimize the oxygen rate of the ambient air (<2%).

Fitted with networks pipes, a set of valves and instruments (flowmeters), this seal gas system is designed to control and distribute seal gas (nitrogen usually) at required flow to defined zone of the hot compactor (force-feeder tank, cheek plates, rolls surface, rolls casing…)


A high automation level ensures a constant continuous operation of the hot compactor. The control-drive system is based on signals from the measurement of the rolls gap, the briquetting pressure value and the force-feeder / rolls drive.

Several control loops are combined in the software programming to ensure a constant and proper running of the hot compactor:
  • Control of the power consumed by the rolls drive by adjusting the speed of the screw shaft.
  • Control of the power consumed by the force-feeder drive by adjusting the speed of the screw shaft.

The control-drive system and associated supervisory developed by SAHUT-CONREUR for controlling the Hot compactor integrates the following features:
  • Industrial SIMATIC PC computer suitable for production applications
  • Supervision software type WINCC
  • Robustness and high availability
  • Data acquisition, management and measuring.
  • Exchange table provided to transfer main signals to whole plant DCS