Potash Processing FEECO OEM

a product of

The

HANDBOOKPOTASH PROCESSINGPROCESSING | EQUIPMENT | MATERIAL CHARACTERISTICS | TROUBLESHOOTING

FROM THE FEECO

MATERIAL PROCESSING SERIES

PROCESSING

INTRO

Contents

About FEECO 1

Potash Then and Now 3

Material Considerations in Handling Potash 4

Uses for Granular Potash 6

Pelletizing Potash 9

Potash Compaction Granulation 12

Drying Potash 15

Cooling Potash 17

Common Potash Processing Issues 19

Maintenance Considerations 21

POTASH PROCESSINGfrom the MATERIAL PROCESSING SERIES

The following is a collection of articles surrounding the topic of potash processing, including everything from

common issues faced in processing potash, to typical process configurations, and even maintenance

considerations. This e-book is part of a larger series from FEECO International - The Material Processing Series.

About FEECO

FEECO International was founded over 60 years ago, as the Fertilizer Engineering & Equipment Company. We have

since grown to provide solutions to nearly every industry, from energy and agriculture, to mining and minerals. We

have become known as the material experts, able to solve nearly any material processing or handling problem.

We are highly experienced in working with potash, be it in material testing and feasibility, process design and

optimization, or manufacturing the best in potash processing equipment.

For further information on potash processing, or for help with your potash operation, contact a FEECO expert

today.

3913 Algoma Rd. Green Bay, WI 54311 Phone: (920)468.1000 Fax: (920)469.5110 Email: [email protected]

Introduction

An Overview of

POTASH

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HISTORY | MATERIAL CHARACTERISTICS | USES

Potash, a naturally occurring mineral, is a form of salt,

and is one of the most commonly found minerals on

Earth. Before it was mined for industrial use, potash

was created through an arduous process involving the

burning of wood and leaching of the resultant ashes,

hence the name, pot-ash.

Early processing was a tedious endeavor, though,

requiring a large amount of lumber to create only a

small quantity of potash. As demand continued to

rise, early processing techniques could not keep up.

Luckily, the discovery of reserves worldwide was able

to appease demand, while also opening the door for

large-scale use of this versatile mineral.

Today, the lions share of mined potash goes to the

agricultural industry, where it has become a staple

in modern fertilizer products. Potash is a form of

potassium, one of the key elements in plant growth

and biological life. And as available farmland

decreases while demand for food increases, never has

it been more important to cultivate more productive

plants with less space. Because of this,

recent years have seen a focus on

nutrient management, and

advanced fertilizer

products.

This has pushed development of advanced processing

techniques in the potash industry and has resulted in

a wealth of available processes and techniques for

processing this vital mineral.

But despite all of these advancements, there is still

a lot of groundwork to be done when it comes to

processing potash into a refined product. Different

deposits yield varying mineral combinations and

present never before seen challenges. In addition,

potash is a demanding material that poses unique

processing challenges, and requires an experienced

hand to produce desired results.

The following takes a look at the various available

potash processing techniques, the challenges

they present, as well as common processing issues,

maintenance, and specialty applications.

Potash Then and Now

POTASH PROCESSING | 3

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Handling a demanding material such as potash

requires dependable performance from each piece

of equipment in a processing facility. The need for

reliability holds especially true for material handling

equipment, which transports potash from one area of

a processing facility to another, adding automation

and flexibility to an overall system.

Bucket elevators, belt conveyors, and so forth must be

designed to manage the rigors and challenges that

potash brings to a facility.

Common Handling EquipmentBucket Elevators are a common piece of material

handling equipment utilized in potash processing

facilities, with double chain, continuous-style bucket

elevators being the most popular choice. Single

chain options are also available, but a double chain

is most often selected due to its increased capacity

and height capability, which is often required in

potash compaction circuits. Bucket elevators transfer

potash vertically, operate at low speeds, and are

able to handle a high capacity of material. Bucket

elevators can be customized to handle the material

considerations of potash, and also offer a variety of

options to fit a facilitys unique needs, such as large

access doors for ease of maintenance, various types

of drive arrangements, service platforms, and more.

Belt Conveyers are very commonly used in potash

processing and potash compaction facilities. Belt

conveyors consist of a continuously moving, carrying

surface (known as a belt) that rotates around two

or more pulleys. As the belt rotates, material is

transported to the desired location. Various conveyor

options are available to assure proper load and

transfer points are accomplished. There are also a

variety of optional pieces of equipment (e.g. belt


K19

39.0983

Potassium

Material Considerationsin Potash Handling

DustyCorrosiveAbrasive

Potash is:

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trippers, loading skirtboards, belt cleaner systems) to

achieve the best material conveying solution for the job.

Potash processing facilities especially benefit from

adding a Belt Tripper to a potash conveyor system.

This complementary piece of equipment offers the

flexibility to use more than one discharge location

(fixed or movable) off of a conveyor system. When

storing potash, this option is especially useful in

creating a long, continuous pile.

Customized Handling EquipmentDepending on the manufacturer, there are a variety

of ways to customize material handling equipment in

order to withstand the abrasive and corrosive aspects

of potash. The customizations listed below are specific

to FEECO:

Material of Construction

Various alloys may be used to defend against corrosion

and other issues. Example: Bucket elevator boot

sections may be constructed of stainless steel to prevent

damage that may otherwise occur from regular use of

a wash down system.

Reinforcing Areas of Wear

High-wear areas are enhanced with heavy-duty

construction, helping these vulnerable zones to better

accommodate the abrasive material. Example: Transfer

chutes and inlet loading areas (standard high-wear

areas in a conveyor) are equipped with wear-resistant

liners.

Dust Build-up Prevention

A build-up of potash fines can cause failure issues. As a

result, protective measures are implemented in areas

that would be otherwise damaged by dust buildup.

Example: Auxiliary seals for bearings are often used in

these areas.

Cover Compounds

Potash treated with a special solution may cause wear or

service issues for certain equipment areas. To counteract

this issue, special cover compounds are utilized. Example:

Potash that is treated with amine solution adversely

affects rubber components such as conveyor belts.


FEECO Dual Drive Bucket Elevator

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Potash is the general name given to various inorganic

compounds that contain potassium in a water-soluble

form. A number of common potassium compounds

exist, including potassium carbonate and potassium

chloride. Before the industrial era, potash was ob-

tained by leaching wood ashes in a pot (hence the

name pot-ash). This product was used to manufac-

ture soap, glass, and even gunpowder.

Today, deposits of potassium-bearing minerals are

mined and processed to compound potash into a

more usable, granular form. Astonishingly, the amount

of potash produced worldwide each year exceeds

30 million tonnes. While most potash is used in various

types of fertilizers, there are many other non-agricultur-

al purposes for this element. Modern processing, such

as potash compaction, produces a readily available

form of potassium, leaving granular potash open to a

myriad of uses.

Top 7 Uses for Granulated Potash:1. Fertilizer Potassium Carbonate, Potassium Chloride,

Potassium Sulfate

Plants require three primary nutrients: nitrogen, phos-

phorous, and potassium. Potash contains soluble

potassium, making it an excellent addition to agricul-

tural fertilizer. It ensures proper maturation in a plant by

improving overall health, root strength, disease resis-

tance, and yield rates. In addition, potash creates a

better final product, improving the color, texture, and

taste of food.

While some potassium is returned to farmlands through

recycled manures and crop residues, most of this key

element must be replaced. There is no commercially

viable alternative that contributes as much potassium

to soil as potash, making this element invaluable to

crops. For this reason, the most prevalent use of potash

is in the agriculture industry. Without fertilizers assisting

crop yields, scientists estimate that 33% of the world

would experience severe food shortages. The replen-

ishment of potassium to the soil is vital to supporting

sustainable food sourcing. Potash compaction gran-

ules blend easily into fertilizers, delivering potassium

where it is needed most.


Uses of Potash

FEECO Conveyor System

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2. Animal Feed Potassium Carbonate

Another agricultural use for potash (potassium carbon-

ate) is animal feed. Potash is added as a supplement to

boost the amount of nutrients in the feed, which in turn

promotes healthy growth in animals. As an added ben-

efit, it is also known to increase milk production.

3. Food Products Potassium Carbonate

The food industry utilizes potash (potassium carbonate)

as a general-purpose additive. In most instances, it is

added as a source of food seasoning. Potash is also

used in brewing beer. Historical Use: Potash was once

used in German baked goods. It has properties similar to

baking soda, and was used to enhance recipes such as

gingerbread or lebkuchen.

4. Soaps Potassium Hydroxide

Caustic potash (potassium hydroxide) is a precursor

to many potassium soaps, which are softer and less

common than sodium hydroxide-derived soaps. Potas-

sium soaps have greater solubility, requiring less water to

liquefy versus sodium soaps. Caustic potash is also used

to manufacture detergents and dyes.

5. Water Softeners Potassium Chloride

Potash (potassium chloride) is used as an environmental-

ly friendly method of treating hard water. It regenerates

the ion exchange resins more efficiently than sodium

chloride, reducing the total amount of discharged chlo-

ride in sewage or septic systems.

6. Deicer (Snow and Ice Melting) Potassium Chloride

Potash (potassium chloride) is a major ingredient in deic-

er products that clear snow and ice from surfaces such

as roads and building entrances. While other chemicals

are available for this same purpose, potassium chloride

holds an advantage by offering a fertilizing value for

grass and other vegetation near treated surfaces.

7. Glass Manufacturing Potassium Carbonate

Glass manufacturers use granular potash (potassium

carbonate) as a flux, lowering the temperature at which

a mixture melts. Because potash confers excellent clarity

to glass, it is commonly used in eyeglasses, glassware,

televisions, and computer monitors.

In addition to the uses described above, potash also

lends itself well to a variety of other applications, includ-

ing aluminum recycling, explosives (in products such as

fireworks and matches), and pharmaceuticals.


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While compaction granulation is the primary method

used to process potash, pelletization is gaining popu-

larity among fertilizer manufacturers looking for a

premium, refined product that can quickly deliver nu-

trients. This process of pelletization is reliable and offers

many benefits to the end product. However, a lot of

work is required in order to produce an optimal potash

pellet; whether its pre-conditioning, pelletizing, or dry-

ing, every step plays an important role in the potash

pelletizing system.

Potash Pelletizing Plant OverviewThe following is an overview of a typical potash pellet-

izing process. See next page for diagram.

Pre-Conditioning

1. First, finely crushed potash enters the pelletizing pro-

cess through a raw material feed bin.

2. Next, the potash travels to the Pin Mixer. The intense

spinning action of the mixer and the addition of a

binder work to pre-condition the material. This process

reduces the air and water volume between potash

particles as it creates densification within the material.

Pelletization via Tumble Growth Agglomeration

3. After conditioning, the potash material is fed onto

the disc pelletizer. Using tumble growth agglomeration,

the potash material gradually rolls and builds against

itself while rotating on the disc. Material is fed at a

controlled rate and water is added to assist in binding

the material. The result is a round, uniform pellet. Pellet

size can be controlled using variables such as disc speed

and angle. Once the potash pellets reach the desired

size, they are discharged from the disc pelletizer.

Product Finalization

4. Because moisture is added during pelletization, a

drying phase is necessary. This is commonly carried out

using a rotary dryer or fluid bed dryer. A rotary dryer

is often chosen for its high efficiency and ability to han-

dle high throughputs. This type of dryer also uses flights

to lift and cascade material as it travels through the

rotating drum. This process efficiently dries material,

prevents clumps, and easily handles a high volume of

potash.

Note: Fluid bed dryers are also an option for smaller processing facilities. This equipment suspends material in a fluidized state, exposing the entire surface of the potash pellet to air.


Pelletizing Potash

Diagram: The diagram above illustrates how flights in a rotary dryer pick up material, carry it over, and drop it through the stream of combustion gas, creating what is called a curtain of material, a process which maximizes heat transfer efficiency.

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5. In addition to drying, potash pellets are often cooled using a rotary

cooler. Similar to rotary potash dryers, rotary potash coolers are a pre-

ferred industrial cooling method due to their robust, heavy-duty con-

struction. Rotary coolers also use a cascading motion to shower potash

material through a cool air stream in the drum. Additionally, they use a

counter-current air stream to cool material and efficiently eliminate the

heat of the potash.

Note: Fluid bed coolers are another cooling equipment option. The fluidized state produced by this

cooler is gentle on potash, avoiding attrition-related material issues.


Diagram Key:

1. Raw Feed2. Paddle/Pin Mixer3. Binder Feed4. Spray Rate5. Disc Pelletizer6. Feed Onto Pelletizer7. Binder Feed8. Liquid Spray System9. Transfer Conveyor10. Rotary Dryer11. Vibrating Screen12. Oversize Mill13. Recycle14. Surge Hopper

Flow Diagram of Typical Potash Pelletizing Process

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6. Finally, the potash material is screened to ensure only optimally sized pellets exit the process. Both the larger

pellets (overs) and smaller pellets (unders) are recycled back into the pelletizing process, while properly sized

potash pellets are bagged and/or stored.

Advantages to Potash PelletizationPelletized potash offers a lot of advantages in terms of processing solutions and product benefits. Because the

process is a non-pressure technique, a potash pellet is an ideal solution for fertilization. In certain occurrences,

pelletization is the only solution for processing specific potash derivatives. The round, uniform pellet shape is less

dense than that of more traditional compacted potash granules, allowing the pellet to deliver nutrients faster.

Fixed formulations especially benefit from this quick break down ability. Moreover, the rounded shape of pellet-

ized potash reduces the occurrence of potash fines due to attrition and is also very easy to handle and apply.


FEECO Disc Pelletizer

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How Compaction Works

Compaction operates on the principle that some materials, when put

under extreme pressure, will adhere to themselves. This principle holds

true for potash and other salts, making these materials ideal candi-

dates for use in compaction granulation circuits. Typically a binder is

not needed to achieve granule formation, but occasionally the addi-

tion of a minor amount of water can help the process.

A screen is often put in place prior to the compactor, in order to sieve

out any tramp material. Potash is then fed via a force feeder assem-

bly (usually a screw system) between two counter-rotating rolls, where

it is placed under extreme pressure. The material exits the rolls in the

form of a compacted sheet, which is then fed into a flake breaker


CompactionDiagram Key:

1. Raw Materials2. Mill3. Surge Hopper4. Humidificator Mixer5. Protecting Screen6. Compactor7. Flake Breaker8. Granulators9. Screen10. Polishing Drum11. Screen12. Screw for Recycles

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and granulator, where it is broken up into the desired granule size.

Keys to SuccessThough the process seems fairly straight forward, there are a few

keys to successful compaction granulation. This is true not only for

potash, but for other materials processed using the roll compac-

tion method as well.

Feeding Mechanisms

The appropriate feeding mechanism design is important to reach

desired product characteristics. An even, steady pressure across

the entire face width is required to create a product of integrity. If

only one large screw is used, the material may be of desired qual-

ity in the middle, but not at the edges. In order to resolve this, a

double screw system can be employed.

Particle Size Distribution

Feedstock particle size distribution is also a key factor in the suc-

cess of a compaction granulation circuit. A variance in particle

size distribution is ideal for the compaction process, so that when

pressed together, smaller particles will fill in the voids between

larger ones.

Too coarse of a particle size distribution, and the particles will not

move through the compactor well. A particle size distribution that

is too fine will also cause deaeration problems.

After CompactionOnce the granules have been created, they can be wetted and

dried in a potash dryer to improve their resistance to attrition. Both

rotary dryers and fluid bed dryers are suitable for this applica-

tion. Throughout this process, material handling equipment such

as bucket elevators and conveyor systems are used to carry the

material from one stop to the next.


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After compaction granulation, potash is sometimes

conditioned in a coarse conditioning drum or paddle

mixer. Its here that any desired additives such as

anti-caking or anti-dusting agents are added, and the

granules are polished to remove any broken or loose

edges.

Compaction vs. PelletizationThe choice between these two methods of process-

ing is one that potash producers commonly face.

Ultimately, cost is often the major factor in determining

which potash process to use. Potash compaction is a

more cost effective process versus potash pelletiza-

tion, making compaction the more popular tech-

nique, though potash pelletizing yields a more refined

product. While potash pelletizing equipment itself

costs less than compaction equipment, the additional

processing cost required in the pelletization method

outweighs this initial cost benefit.

Though cost is most often the determining factor, there

are advantages and disadvantages to each method

that could ultimately dictate the process to be used.

Additionally, as previously mentioned, some potash

derivatives may only be processed using the pellet-

ization method, due to material characteristics. The

primary considerations for both processes have been

summarized in the table below:

Pelletization Compaction

Produces round, smooth pellets Produces jagged granules

Less attrition More cost-efficient

Product breaks down faster Binder not required

Binder required

Premium product


FEECO Rotary Dryer

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DryingDrying is a vital aspect of processing potash

into a usable form. Not only does drying help

to create a better end product, but it can

also aid in preventing process issues due to

moisture, such as clumping.

Benefits of Drying PotashThe drying process accomplishes many benefits

for potash such as:

Reduced Moisture

The drying process reduces moisture in potash, di-

minishing material handling issues such as clumping.

Round, Polished Granules

Rough granule edges wear down other granules and pro-

duce a large amount of fines, a process referred to as attrition.

Drying rounds and polishes granules, reducing the opportunity for

attrition to occur.

Hardened Granule Surface

Potash drying flashes residual moisture off quickly, leaving a hardened, more robust potash gran-

ule with a re-crystallized surface.

Why Dry Potash?After potash is mined, it undergoes processing to extract potassium from minerals and create a final potassium

product in a readily available form. Agglomeration is part of the overall processing used to achieve an optimal

potash product, with compaction granulation or pelletization being the primary techniques. Drying comple-

ments both processes.

Compaction Granulation and Drying

As previously discussed, compaction granulation is the most frequently used solution to agglomerate mined

potash into a readily available product.

Compaction is a dry process; consequently, this procedure does not always include the use of an industrial

dryer. However, even when using a seemingly straightforward process such as compaction, there are special


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material considerations that need to be addressed.

For instance, the issue of attrition mentioned earlier. To

improve resistance to attrition, the compacted gran-

ules are often wetted and then dried in an industrial

dryer. The goal is to fill cracks inside the particles and

eliminate sharp granule edges, reducing dusting prob-

lems that would otherwise occur when the material is

shipped and handled. Both rotary dryers and fluid bed

dryers can be used to dry the potash granules after

they are wetted.

Pelletization and Drying

A wet process, pelletizing requires a binder to adhere

the potash to itself in pellet form. Because the binder

also adds moisture, a drying phase is necessary. As

with granulated potash, rotary dryers and fluid bed

dryers are excellent industrial dryer choices for pellet-

ized potash.

Potash Drying Equipment: Rotary Dryers vs Fluid Bed DryersA rotary dryer is a robust, long-lasting equipment

choice for drying potash. Flights within the rotating

drum lift and cascade material as it tumbles through

the drum, preventing material clumps and promoting

an evenly dried final product. Rotary dryers accept a

wide variability in feedstock, a high volume of mate-

rial, and are ideal for rounding the sharp edges of

compacted potash.

Fluid bed dryers use pneumatic conveying to dry ma-

terials. By suspending potash in a fluidized state, they

expose the entire surface of each granule, increasing

a materials drying efficiency in certain applications.

These dryers have the advantage of being smaller

than rotary dryers, which is beneficial in processing

facilities with limited space. Fluid bed dryers are also

modular, which is well-suited for operational growth

in the future. However, their downfall is that they are

unable to accept a wide range of variability in feed-

stock, and do not round or polish granules. In addition,

they require significantly more air-flow, resulting in the

need for larger dust collection systems and fans.

In terms of energy, the most efficient equipment

choice varies. Material considerations such as volume,

weight, and feedstock variability should be consid-

ered when determining which machine will be the

most suitable and energy efficient solution.

Material Considerations in DryingWith any material, there are material-specific consid-

erations that must be considered during the drying

process. Potash is no different.

Air-flow

A co-current air flow, meaning the potash and air

stream flow in the same direction, proficiently dries

the material. This maintains the integrity of the prod-

uct, because the hottest gases come in contact with

the wettest material. If a counter-current dryer were

chosen, the hottest gases would come in contact with

the driest material, which can discolor potash, cause

attrition, and/or hurt the quality of the end product.

Corrosion

Because potash is a corrosive material, specialty

materials such as alloys are often employed on pro-

POTASH PROCESSING|16

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cessing equipment. For example, stainless steel is often

used at the front end of equipment in order to coun-

teract the products eroding characteristics.

Clumping

Potash is also apt to clump during the drying process.

For this reason, knocking systems can be added to

a rotary dryer as a means of dislodging material that

may have built up on the interior of the drum. A vari-

ety of knocking system design options are available,

and can be retro-fitted to an existing system.

Another solution used to avoid lumps is to employ a

screw conveyer. The feed trajectory of a screw con-

veyer will fling or throw the potash into the dryer,

breaking up clumps in the process.

Drying potash creates a multitude of benefits, result-

ing in an optimal final product with minimal moisture,

clumping, and dusting issues. With so many challeng-

ing material considerations, it is clear that potash dry-

ing requires well-designed equipment to get the job

done right.

CoolingPotash coolers are also an important step in the pot-

ash manufacturing process. While a straightforward

task, cooling is still a large undertaking that requires

flexibility and expertise in order to finish with a better

potash product overall.

Why Use a Potash CoolerCooling provides a number of advantages that trans-

late to an improved potash product. This includes:

Increased Potash Process Efficiency

Adding a cooler to the manufacturing process offers facil-

ities the ability to handle, bag, and store potash immedi-

ately, avoiding other time consuming cooling methods.


FEECO Rotary Cooler

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Reduced Potash Storage Issues

Cooling potash before bagging prevents issues such as sticking or

caking during storage.

Enhanced Potash Granule Robustness

The process of cooling potash creates a more resilient final prod-

uct that is less likely to wear down as granules come into contact

with each other.

Options for Potash CoolersRotary coolers and fluid bed coolers are standard potash cooling

equipment, with the choice between the two often varying based

on customer preference. In general, both options handle material

gently and avoid attrition, key qualities in industrial cooling equip-

ment. However, they each offer unique advantages to the potash

cooling process:

Rotary Coolers

Rotary coolers are robust, long-lasting, and accepting of a wide

range of feedstock when cooling potash. In general, a standard

rotary cooler is much larger than a fluid bed cooler. Because of

its greater size, a rotary cooler is able to handle a higher material

volume, making it an ideal choice for potash processing facilities

running at a high throughput capacity. Similar to dryers, rotary

coolers also have the advantage of requiring less air-flow, and

therfore smaller dust collection systems and fans.

The heavy-duty construction of a rotary cooler is especially suit-

able for handling a challenging material such as potash. As the

drum rotates, flights within the cylinder lift the potash and shower

the material through the air stream. While not as gentle as a fluid

bed cooler, the tumbling within the drum benefits the material by

further polishing the potash granule.


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Fluid Bed Coolers

Fluid bed coolers are a modular, smaller potash cool-

ing equipment option. These advantages make fluid

bed coolers ideal solutions in facilities with limited

space or potential operational growth.

Fluid bed coolers suspend potash in a stream of air or

gas, efficiently cooling potash by exposing the en-

tire material surface to air. This method also provides

gentle material handling, preventing erosion and wear

between potash granules.

Potash coolers add efficiency and quality to potash

manufacturing, making industrial cooling equipment

such as rotary coolers and fluid bed coolers an invalu-

able part of the potash industry.

Processing ChallengesMore than 30 million tonnes of potash are produced

worldwide each year, making it an important mineral

for a number of product manufacturers, as well as an

integral component in fruitful crop production. Howev-

er, potashs widespread use does not mean it is always

easy to process; demanding material characteristics

combined with unique processing requirements can

present challenges during processing.

As mentioned, there are two primary methods by

which potash is processed: tumble-growth agglom-

eration on a disc pelletizer, or through compaction

granulation in a compactor. Each of these methods,

combined with the characteristics of potash, presents

its own unique challenges. The following list highlights

some of the most common challenges experienced

during potash processing when utilizing these two ap-

proaches.

PelletizationMoisture Levels

Throughout the pelletization process, achieving and

maintaining ideal moisture levels is a critical consid-

eration, affecting nearly all parts of the process, as

well as the outcome. Moisture levels must be carefully

monitored during conditioning, pelletizing, and drying.

Conditioning potash in a pin mixer prior to the disc

pelletizer is a common practice in the pelletization

method of processing potash. Here, two things are


Corroded Rotary Dryer Flights:The result of a poorly designedand constructed rotary dryer.

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accomplished: raw material fines are vigorously mixed

with a binder to create a homogeneous mixture, and

raw material is brought up to the appropriate mois-

ture level for optimum pellet formation. Too little or too

much moisture in this stage will cause the material to

be ill prepared for pellet formation on the disc pellet-

izer.

Once the potash is fed onto the pan pelletizer, pellet

formation begins. Here, additional binder is added to

increase tackiness and foster desired pellet growth.

In this stage too, moisture is of crucial concern. Too

little or too much will not allow for desired pellet size or

characteristics.

After the potash has been pelletized, the green

pellets must be brought down to the moisture level

required for the end product. It is here that an industrial

drying system must be employed. A dryer such as a

rotary dryer, specifically designed around material

and process requirements, will achieve the best results.

In addition, a co-current air-flow will ensure product

integrity is maintained.

Compaction GranulationAttrition

The process of compaction granulation creates

compacted potash granules with rough surfaces and

jagged edges. Consequently, rough surfaces and

jagged edges wear against each other, in a process

referred to as attrition. Not only does the size and shape

of the compacted potash granules change through

attrition, but a large amount of unwanted potash fines

are also produced, resulting in a dusty product, and

material waste. This occurrence is minimized through

the addition of a polishing drum. In a polishing drum,

granules are tumbled, causing loose edges to break off,

rounding out and polishing the product. The resulting

fines are subsequently removed during screening and

used as recycle in the compaction circuit.

As an alternative to a polishing drum, a paddle mixer

may be added after compaction. In this configuration,

compacted granules go from the compactor to the

paddle mixer, where they are wetted and then dried

in a rotary dryer. This act of wetting and drying the

granules helps to eliminate sharp edges, as well as fill

in surface cracks on the granules that would otherwise

contribute to attrition.

General IssuesClumping

Potash, due to its hygroscopic quality, is often prone to

clumping, sticking, and caking issues. These issues may

show up during drying, or storage. However, there are

steps that can be taken to combat this.

Drying: Knocking systems can be added to rotary dryers

as a method to break up lumps amongst the material

itself, as well as dislodge any material that may be

sticking to the interior of the drum.

Screw Conveyors: Another equipment-based solution

to prevent clumps is the addition of a screw conveyor.

The screw conveyor utilizes a feed trajectory that flings

potash into the dryer. This motion efficiently conveys the


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material and breaks up lumps in the process.

Anti-Caking Additives: Anti-caking additives are

applied to finished granules through the use of a paddle

mixer. A variety of anti-caking additives are available,

depending upon material characteristics and end

product use.

Corrosion

Another potash processing challenge that manufacturers

experience is corrosion. Since potash is a corrosive material,

it can progressively destroy metal through chemical action.

For certain equipment, special accommodations must be made in order to

counteract the corrosive nature of potash. One example of this customization is

the use of stainless steel or nickel alloys on areas of the equipment that come into

contact with potash during processing.

Maintenance ConsiderationsA potash processing facility includes many pieces of equipment that are not only a big

financial investment, but also critical to daily operation. In order to protect investments,

prevent costly downtime, and extend the life of equipment, regular potash equipment

maintenance is a necessity.

Potash Equipment Preparation

The key to maintaining a quality potash processing operation is to utilize equipment that has been prepared

to handle the unique material characteristics of potash. For example, FEECO utilizes corrosion and rust resistant

techniques to make the potash processing equipment more resilient to the corrosive effects of potash.

For Corrosion Resistance and Rust Prevention

In order to prevent corrosion, equipment may be customized with stainless steel or nickel alloys in areas affected

by potash during processing. In addition, equipment may be covered with UHMW (Ultra High Molecular Weight

Polyethylene) to further prevent contact between potash and the metal of the equipment.

The composition of potash essentially includes salt. Consequently, water used during processing creates an

opportunity for equipment to rust. In order to prevent rust, equipment should be fully seal welded. This prevents

material from entering any nooks or gaps within the machinery.

Material Build-up


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The most important aspect of potash processing maintenance is to minimize material build-up. Material should

be moved through equipment as needed and should not be allowed to sit in equipment for unnecessary

periods of time. This is especially important if extended periods of down-time are expected.

Potash Equipment MaintenanceAnother way to support potash processing maintenance is through routine upkeep and standard inspections

of processing equipment. Basic pieces of equipment common to a potash processing operation include

compactors, rotary dryers (also referred to as potash dryers), bucket elevators, and conveyor belts. Potash

processing maintenance is critical for these machines, because they are used regularly and process a large

quantity of material. The performance of this equipment is contingent on regular maintenance performed

properly at designated intervals.

In addition to the tips listed above, the following lists highlight the preventative maintenance program for key

potash processing equipment.

Note: This is not a complete maintenance list. Always consult your original equipment manual for more details and to ensure all necessary maintenance is followed. Maintenance should always be performed by a trained professional.

Bucket Elevator Maintenance

The two head bearings and the two boot take-up bearings should be lubricated regularly. Each of

these four lubrication points should be serviced at least once a week.

The drive motor, speed reducer and couplings, and chain and sprocket drive should also be inspected

and maintained per manufacturers recommendations.

Periodic inspections should be conducted on the following components: drive system chains; the

elevators vertical position; the head and boot pulleys (to ensure the belt is centered); electrical wiring

and its associated contacts and switches; and nuts and bolts (to ensure they are properly tightened).

It is especially important to clean out the boot after each use if the elevator is used seasonally to

handle potash. The equipment should be operated for a short period of time every two weeks to

ensure belt flexibility is maintained.


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Conveyor Belt Maintenance

Material build-up will accelerate wear on all components, especially when the equipment handles a

corrosive material such as potash. Ensure that the conveyor is properly cleaned regularly.

Periodic inspections should be conducted on the following: scraper mechanisms; belt tracking; idler

wear; roll freeze; extended grease fittings; and the drive sprocket and chain.

Lubricate the following components as directed by manufacturer recommendations: bearings, idlers,

motor, speed reducer, and drive chain.

Compactor Maintenance

Through normal wear and tear, compactor rolls need repair, and eventually, replacement. Not

surprisingly, the centers of the rolls wear faster than the edges, requiring that the outer portions

occasionally be machined down to again achieve a relatively flat surface.

Cheek plates and force feeder screws are also common wear components that require occasional

replacement.

Potash Dryer Maintenance

Regular cleaning should be performed to ensure material build-up is prevented.

Periodic inspections should be conducted on the following: bearings, drive chains, couplings,

hammers, motor, reducer, trunnion wheel/tire contact pattern, v-belts, burner system, internal devices,

thrust assemblies, girth (bull) and pinion gears, and floating tire assemblies. In addition, the following

contacts should be visually inspected: breeching seals; thrust rollers to tire; and trunnion wheels to tires.

Lubricate the following components as directed by manufacturer recommendations: bearings, drive

couplings, drive motor, thrust assemblies, floating tire assemblies, trunnion wheel bearings, and trunnion

wheels and tires.


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For more information on potash processing, lab testing, custom equipment, or for help with your potash operation,

contact FEECO International today!

3913 Algoma Road | Green Bay, WI 54311920-468-1000

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Copyright 2015 | FEECO International, Inc. All rights reserved

Potash Processing FEECO OEM

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