Köppern, Maschinenfabrik GmbH & Co. KG

Cold Briquetting

For cold briquetting of material with temperatures of up to 100°C / 212°F it may be necessary to add binders to improve the briquette forming characteristics. Typical briquette sizes range between 1.5 and 250 ccm. As a result of the symetrical pockets machined into the surfaces of the rollers, briquette machine production yields very uniform briquettes. Binders are primarily used for the briquetting of substances that have an inadequate adhesive power and are unable to produce a firm briquette.

In this manner, coal dust has been converted into oval shapes used as domestic fuel for more than 100 years now. Material to be briquetted without additive binders is fed between two counter-rotating profiled rollers via suitable feeding equipment.

The feedstock is drawn into the briquetter and pressed through the gap between the rollers. As a result of its void volume being reduced, the bulk materials apparent density will be compacted by factor of 1.5 - 3.

Examples of briquetting applications are e.g.:

• Ashes
• Burnt lime
• Chrome ore
• Copper concentrate
• DMT
• Dried sewage sludge
• FGD gypsum
• Filter dusts
• Iron oxide
• Magnesite
• Magnesium oxide
• Metal chips and turnings
• Mill scale
• Salt
• Sodium cyanide
• Sponge iron
• Steelwork dusts

Compacting

The machinery used for compaction and briquetting is basically identical, but there is one noteworthy difference: in lieu of the matching molds used in briquetting the surfaces of the compaction rollers are smooth, corrugated or waffled. In the event that the fineness of a single- or multi-component bulk material causes drawbacks such as segregation, agglomeration, unfavorable flow characteristics or dust losses the process of compaction/granulation is employed for size enlargement.

Press agglomeration in the absence of binders via roller presses is a basic process by means of which a size enlargement is achieved primarily without the material bridges between particles being established with the aid of binding agents. Instead, the molecular forces of interaction play a significant role, but only if the individual particles can be brought together as closely as possible. This calls for external compressive forces to be applied.

If solid substances compression takes place in the gap between two smooth or profiled rollers running counter to each other, this is known as compaction. A compaction in conjunction with downstream crushing or classifying operations forms the compaction/granulation process. The principle design of a compaction/granulation system is evident from the following diagram assuming a multi-component bulk material to be processed which is used, for example, in the compaction of mixed fertilizers/NPK.

The system comprises four machinery and vessel groups essentially used to perform the following process steps:

• Storage, dosing and blending
• Compaction
• Crushing and classifying
• Final treatment

By means of various conveying systems such as bucket elevator, belt and chain conveyors as well as other conveying devices, the material is transferred to the individual process steps.

This technology is frequently used for the compaction/granulation of potassium chloride (MOP). Millions of tons of granulate are thus produced each year. The largest Köppern presses in operation feature a throughput capacity close to 130 t/h. The granulate yield depends on the particle size range as well as type and treatment of the crude salt and ranges between 35 and 55 t/h with a granulate size of 1-4 mm.

Aside from using the compaction/granulation process for the treatment of individual fertilizers ((i.e. potassium chloride (MOP), potassium sulfate (SOP), ammonium sulfate(AS)) it is also employed for mixed fertilizers ( NPK fertilizers).

Further applications are in the chemical industry and salt mining.

High Pressure Grinding (HPGR)

During high-pressure grinding in roller presses coarse materials, such as cement clinker, ore or limestone, are briefly subjected to very high compressive forces. The sheets thus produced can be ground and thus reduced to the desired final particle size with minimum energy requirements.

High-pressure grinding rollers ( HPGR) are employed in various combinations with other equipment for preliminary and finish grinding. Energy savings is the most important factor for using this technology.

Depending on the grinding system used, capacity improvements of up to 250% and/or a reduction of the specific energy consumption of up to 40% can be achieved. To suit the respective application, three different types of rollers are available:

• Solid rollers
• Rollers with tires
• Rollers with segments

The following wear protection systems can be applied:

• Hardfacing by welding
• Chill casting
• Composite materials
• HEXADUR (R)

Köppern high-pressure grinding rollers are easily operated and maintained. Thanks to drive and roller components being arranged separately, the rollers can be quickly removed and replaced for maintenance needs.

Wearing parts of the gravity-type feeder can be simply replaced from the outside. Various drive systems are available. Materials presently treated in high-pressure grinding mills cover:

• Cement clinker
• Slags
• Limestone
• Fine ore/pellet feed
• Kimberlite
• Ores
• Coal and
• Kieserite

Hot Briquetting