What is hot briquetting

The term ‘hot briquetting’ is used when the temperature of the feed material requires the use of highly heat-resistant roller presses that incorporate special arrangements for cooling.

Materials are briquetted under hot conditions if binding characteristics are activated at high temperatures.

Following its industrial development in the 70s and 80s, hot briquetting is now a fully-accepted, reliable technology for the passivation of direct-reduced iron (DRI) to turn it into the more convenient form of hot-briquetted iron (HBI).

Materials are briquettable under hot conditions if binding characteristics are activated at high temperatures. The most common application is the production of hot briquetted iron (HBI) from direct reduced iron (DRI), whereby the feed is charged to the roller press while still hot as it leaves the reactor. Alternatively, materials can be reheated, as for example in the hot briquetting of converter dust.

Roller presses and auxiliary equipment (e.g. briquette string separators, hot screens, hot fines recycle systems) all can supplied by Maxton to cope with the high temperatures. This involves the use of high-temperature resistant steel, the water-cooling of various machine parts as well as inertisation of housings to prevent re-oxidation.

Applications

  • coal;
  • converter dust;
  • foundry dust;
  • lead bearing waste;
  • magnesite;
  • magnesium oxide;
  • mill scale;
  • steel mill dust;
  • zinc bearing dust;
  • sponge iron from – lump ore, pellet and ore fines;

Differences between a hot briquetting and cold briquetting

 Cold BriquettingHot Briquetting
Temperature
ambinet up to 50 ℃≤250 ℃≤450 ℃≤850 ℃
Cooling of equipmentnoneyesstrongintensive
Types of steelcarbon steelcarbontemperature resistance low alloyhighly beat resistance high alloy

Hot briquette system

Modular construction for customized flexibilityThe key component in hot briquetting is a specially designed roller press. The entire plant for the hot briquetting of sponge iron typically consists of:

  • Briquetting press with screw feeder and material supply
  • Briquette string separator
  • Hot screen for elimination of fines
  • Product cooler
  • Bucket elevator for re-circulation of hot fines to briquetting press, plus chutes and accessories

Features

Hot briquette roller press are equipped with additional features to cope with the high operational temperatures:

  • Water-cooling of heat-sensitive parts such as the pressing tools
  • Inert gas supplied via various feed points to reduce re-oxidation of the DRI within the roller press
  • Use of high temperature-resistant steels
  • Parts designed to allow for thermal expansion
  • Specific pressing forces up to 150 kN/cm

HBI briquette making

Hot briquetting is a reliable, fully developed industrial concept for the passivation of direct reduced iron produced with the various processes of direct reduction. Because, during hot briquetting, the large specific surface area of direct reduced iron is drastically reduced, the well known problems caused by reoxidation, overheating are avoided. Even the shipping instructions published by the International Maritime Organization (IMO) confirm that Hot Briquetted Iron (HBI) can be handled and shipped without special precautions

The HBI briquetting process

HBI making process drawing

Parameter for the hot briquette roll machine

ModelRoller Diameter (mm)Roller Width (mm)Total Pressure (kN)Linear Pressure (kN/cm)Capacity (m3/h)Main Motor Power
HBP48048080-120100080-150230-37
HBP580580125-200150080-1504.555-75
HBP720720180-270220080-150790-110
HBP850850250-375300080-15010185-200
HBP10001000330-500400080-15013250
HBP12001200400-625500080-15020285-355

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