DH series dry type roller press compactor

Material Granulated by compaction

· Ammonium chloride ·Ammonium sulfate ·Burntlime ·Calcium nitrate · Dry municipal sludge ·De-icing salt · Industrial potash ·Micro-nutrients ·NPKfertilizers ·Potassium rock · Potassium chloride · Potassium sulfate ·Sodium carbonate(soda) ·Sodiumformate · Sodium chloride ·Sodium nitrate ·Sulfate of potash magnesia ·Bentonite

Compaction is the process of compressing fine-grained solids between counter-rotating smooth or profiledrollers. The resuting band of material, known as flake, is an intermediate product from which the final granulate isproduced using crushing and screening processes

While the technology is also found in many chemcial industry applications, the compaction processtraditionally is mainly used to produce either single-component(KCL,SOP,AS) or muticomponent(NPK) fertlizers.

Technology Focused On Fertilizer Production

Besides signle-component fertilizer which for example contain only K(potassium), mixed fertilizer are alsoavailable. These each contain either two or all of the nutrients N(nitrogen),P(phosphor) and K. The use of granulated fertilizers largely avoids segregation, uncontrolled agglomeration and unsatisfactoryflow characteristics, or losses during application due to dusting or run-off.

In contrast to the wet granulation process, compaction-granulation requires neither drying nor the addition ofbinders.

Fuyi not only manufactures rollers presses but also provides complete fertilizer production plants. Additionally,our range of services includes compaction tests, process layout, basic engineering plus installation and start-up support.

Design Feature

Compaction with roller presses follows a simple principle: a fine raw material is fed into the space betweentwo counter-roating rollers, where it is then compressed and formed into flakes. The main functional assembliesprovided for this purpose are:   * Press frame  * Pressing rollers with bearings and bearing housings  * Main drive with reduction gear  * Material feeder: Quantitative screw feeding and forcedscrew feeding  * Hydraulic pressuring system  * Grease lubrication  * Roller housing

The fixed roller is supported directly in the press frame, while the so-called floating roller is also supported inthe frame. The movement of the floating roller constitutes the basic principle of a roller press. The rollers are driveneither by one electric motor in combination with a double-shaft gear box and tooth couplings.

The extent of the roller movement defines the roller gap. It is a function of the pressing force generated by thehydraulic system in relation to the reaction forces exerted by the material being processed and the preset"zero-position" of the roller gap. Depending on the requirements of the specific process, the gap itself is controlled by
means of feed screw speeds.

These design features guarantee that all the feed material passes through the roller gap under the sameprocess conditions, thus ensuring that the output quality of the product remains constant. Normally,the roller materials adopts alloy steel. They are sufficiently wear-resistant to ensure maximum service life and minimum expense, whereby conventional pressing tools can be refurbished and re-used.  A roller housing is provided for safety reasons and to minimize dust emission.

Factors determining the selection of machine type are:

·Required application
·Attainable peripheral speed
· Specific pressing force requirements
· Product shape and size
· Design of pressing tools and material feeders

Flake Breaker
Flakes exiting the roller press are typically too large to be conveyed. This is why a flake breaker is ofteninstalled directly beneath the roller press. A special chute can be added that allows flake samples to be taken. It ismainly composed of crusher housing and chamber, rotary crushing cutter wheel, motor, reducer, bearing seatmain shaft and upper and lower material inlet and outlet. The crusher housing is composed of the main shaft andthe rotary crushing cutter wheel, and the main shaft is driven by the motor.

Equipment parameters

Process Technology

Comprehensive and Customized

The gereral flow sheet of a fertlizer compaction-granulation plant comprises three process groups ofmachinery corresponding to the following process steps:

* Feed material preparation
* Compaction-granulation
* Post-treatment

The material is transported within the plant by various means such as bucket elevator or belt and scraperconveyors.

Feed Material Preparation

Typically, the feed materials are dosed and processed continuously, whereby the number of bins useddepneds on the number of feed material components to be incorporated in the final proudct. Some feed materialsrequire crushing. either to reduce feed size or to break up coated surfaces. Drying or pre-heating may need to be foreseen depending on the feed material.

In some multiple fertilizer plants(NPK fertilizers), batch dosing and mixing has also been applied.Components are metered into a weigh bin. The completed formulation is then discharged into a batch mixer. Asurge bin connects the discontinuous feed preparation with the continuously operationg compaction process.Whichever operation is used, the selection as well as the arrangement of mixer, crusher and dosingequipment requires careful consideration.

Compaction-Granulation

Using FUYI roller presses based on the principle of press-agglomeration, material is introduced into the gapof the two counter-rotating rollers by vertical forced feed screws. As the material is compacted. pressure within thematerial increases, reaching a peak just above the line of closest approach between the rollers, and subsequentydropping rapidly to zero.
During this process, the apparent density of the mixture increases by a factor of 1.5-2 due to the decreasingvoid volume of the bulk material. The resulting product is typically a flake of 5-45mm thickness.

The flake produced in the roller press must be broken up and classified into the desired particle size range.Often, the first crushing step takes place in a specially designed flake breaker installed directly below the rollerpress. The flake is broken into smaller pieces which make suitable feed for subsequent crushers

Using a multi-deck screen, the material is then separated into oversize, product and undersize fractions.The undersize(which passes directly through to the lowest screen deck) is re-circulated for compaction, while theoversize forms a residue on the upper screen deck which is fed into the crushing process. Many mixed fertilizers, particulary those containing phosphates and/or urea, initially priduce relatively soft.plastic flakes that harden during aging. For this, a curing bin is installed ahead of the crusher.

The economics of a fertlizer compaction-granulation system depend strongly on the appropriate roller pressdesign and the correct selection of crushing and sizing equipment. In addition to particle shape and size ranges.the compaction process as wellas the crushing and screening circuits determine the yield and output of a plant.

Post-Treatment

Fertilizer granules are exposed to mutiple stresses in the logistics chain during transportaion, storge and packaging. Such stresses can be caused by:

*  Static strain due to the high load during storage

*  Friction between the granules under high load while beingremoved from storage

* Friction between the granules while being conveyed in bulk streams(conveyor transfer point, chutes)

*  Impact on each other, or on metal or concrete surfaces

* Avsorption and emission of water during storage and/ or transport.

Two possible post-treatment methods can be used to reduce the effect of these stresses.

Standard post-treatment

* Polishing   *Coating

First of all, the irregular-shape particles are polished inan abrasion drum in order toround off sharp edges andcorners. The fines producedare removed by single-deckscreening and subsequently recirculated to the compaction circuit. They are then coated wth an anti-cakingagent, which helps to prevent not only the caking of individual particles but also dust generationcaused by abrasion.

Advance post-treatment

* Polishing
*  Moisturizing
*  Drying/Cooling
* Coating
Additional finishing steps,such as moisturizing followed by drying and cooling,improve the abrasion resistance of individual fertilizer granules.

Process Flow (PID)Application

Fields Of Application

Compaction-Granulation Plant

Single-Nutrient Fertilizers

The illustration shows a compaction-granulation plant for MOP with 60%K20 content. Compaction of suchlertlizers typically takes place at elevated feed temperatures, the crushers working in a closed-loop cycle withmulti-deck screens to crush the flakes into granules.

In some cases, raw materials already process good abrasion resistance, so that post-treatment of thegranulate is not required.

The granulate capacity depends on raw material properties and the desired product grain sizes, as well ason the equipment selected for subsequent crushing and screening.
For AS and SOP, a small amount of moisture is added prior to compaction. Since these materials are alsotypically processed at elevated temperatures, no additional drying is required.

Further components for individual compaction-granulation are:
* ammonium sulfate(AS)
* potassium sulfate(SOP)
* MOP with 40% K₂O

Multi-Nutrient Fertilizers

Today's intensive farming demands the use of muti-nutrient fertilizers. To improve their application to thefield, several techniques have been developed which produce.

* uniform
* dust-free
*  non-segregating

Compact Plant Design

Granular products(also known as compound or complex fertilizers( from fine-grained or powdery rawmaterials.)

In contrast to conventional wet methods, the granulation of fertilizers by compaction uses dry feed material.These materials can come from an almost unlimited number of sources, whereby there are no special requirementsregarding particle size or distribution, and no drying is necessary.

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