Briquetting Without Binder

A number of substances can be converted into product of adequate strength without the addition of a binding agent. The material must of course possess inherent binding properties, whereby the bonding can be achieved in a number of different ways:

Plastification under pressure

Structures (crystalline or non-crystalline) are forced into each other and when the pressure is then reduced, the structures rearrange themselves and form an almost natural bond. This effect can for example be observed in various salts (NaCl, KCl) or metals during molding inside the briquette press machine.

Binder "on board"

One example is the lignin contained in biomass. On being subjected to pressure, the inherent lignin is squeezed out of the original structure into the voids between the particles, which is the core forming principle of the roller-based briquetting equipment mentioned above.

Mechanical linkage

The particles interlink on account of their shape (e.g.metal turnings).

Capillary forces

Small water bridges from the bond between the particles. This requires a fine particle size distribution along with the correct proportion of water. The briquettes are soft and their physical properties are not suited to severe handling or transportation situations.

The briquetting process as such is quite simple. Raw material are metered out and homogenized before being fed to the roller press briquetting machine. FUYI tailors the roller press to the customer's requirements in terms of the whole performance of briquetting with roller press machine.

* gravity feeder/screw feeder

* roller speed

* (specific) press force

* torque of the main drive

* briquette size and shape

* number of roller presses

* etc

The roller press output can be screened so that undersize material is recycled back to the roller press.

Briquetting without binder-typical raw material

* Aluminum
* Bentonite
* CaOBurnt lime CaO
* Caustic dolomite
* Caustic magnesia MgO
* Clay
* Dimethylterephthalate DMT
* Flue dust
* fly ash
* Fluorspar
* Gypsum
* Lateritic iron ore
* MAMaleic anhydride MA
* NaClSalt NaCl
* Sodium cyanide NaCN

Briquetting With Binder

Briquetting with binder–typical mixes

* Chrome ore with molasses/ hydrated lime
* Coal with bitumen
* Coke fines with starch
* Copper-nickel concentrate with lignosulfonate
* DR/HBI plant residues with bentonite
* DRI fines with molasses/ hydrated lime or sodium silicate/ hydrated lime
* Feed for RHF–based DR process with starch
* Molybdenum oxide with ammonia solution
* Nickel powder with PVA
* Steel plant residues with molasses/ hydrated lime

For cold briquetting at feed material temperatures of up to 100℃, it may be necessary to add binders to improve the briquette-forming characteristics of the roller press briquetting machine.

Binders are primarily used for the briquetting of substances that have inadequate adhesive properties and are thus otherwise unsuitable for the production of firm briquettes. An example is the ubiquitous egg-shaped coal briquette, which has been produced from coal fines for well over 100 years. Today, briquettes are usually pillow-shaped, with sizes ranging from 1.5 to 60cm³. However, depending on the material to be briquetted and the customer's specific requirements, other forms and sizes of briquette are compatible with the briquette press machine.

A variety of binding agents is available, but certain criteria need to be met for the right choice of binder. Clearly, the binder must function properly and the briquettes need to be robust enough to withstand handling on the way from the roller press to their usage destination. The subsequent processing also has its specific requirements; for example, a binder that corrodes the lining of a metallurgical vessel will not be suitable, no matter how good its physical properties may be. And from an economic point of view, the binder must be available in sufficient quantities and at an acceptable price per ton of product.

Binders can be classified as:

* Glucosidic (e.g. molasses, starch)

* Inorganic solutions (e.g. sodium silicate)

* Clays(e.g. bentonite)

* Thermoplastic (e.g. bitumen, pitch)

* Mortar-type(e.g. cement, hydrated lime)

* Non-glucosidic organic solutions (e.g. resins)

* Fibers(e.g. paper fluff)

The briquetting process must take into consideration the handling of the binder including its storage and dosing. Furthermore, a mixer will be required to ensure sufficient penetration of the binder, and the feed mix needs to be free-flowing in order to avoid the formation of binder nests, a key precondition for stable briquetting with roller press machine. Optimizing the distribution of the binder will also have a positive effect on operation costs.