ThyssenKrupp Tom Armesy - The IPCC Challenge Putting All the Pieces Together

7/29/2019 ThyssenKrupp Tom Armesy - The IPCC Challenge Putting All the Pieces Together

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ThyssenKrupp Robins

ThyssenKrupp Robins, Inc.7730 East Belleview Ave., Suite #404Greenwood Village, Colorado80111-5820, USAPhone: 303-770-0808 Fax: 303-770-8233E-mail: [email protected]

The IPCC Challenge: Putting All the Pieces

Together

Submitted by: Tom Armesy

ThyssenKrupp Robins, Inc.

The IPCC Challenge: Putting All the Pieces Together


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Increasing overburden ratios, longer transport distances, higher fleet operatingcosts, and the potential to reduce these costs are leading a number of mining

companies to consider an In-Pit Crushing & Conveying system, commonly called

IPCC systems, as a way to gain a cost advantage for future operations.

In-Pit Crushing and Conveying is certainly not a new concept. The first fully

mobile IPCC systems were supplied to the cement industry in Europe over a half

century ago by the ThyssenKrupp

Frdertechnik group in Germany. Other

international manufacturing companies have

designed and supplied semi-mobile in-pit

crushing systems for several decades.

However, plant design and equipment

capabilities have progressed significantly

since that time and modern high capacity IPCC

systems, with their inherent advantages, are

increasingly considered as a viable option.

1956 Nordcement, Hannover, Germany

Photo courtesy of ThyssenKrupp Frdertechnik

In todays world, with the advances in equipment and control technologies, the

key to successful implementation of an IPCC concept is a comprehensive project

evaluation approach integrating the mine planning needs, the operational

requirements, the environmental requirements, and the equipment required to

deliver a crushed product from the mine face to the next destination.

The term In-Pit Crushing & Conveying encompasses stationary in-pit crushing

stations, semi-mobile crushing plants (shown here), and fully mobile systems.

This paper will focus on Semi-Mobile and Fully

Mobile IPCC Systems.

While lower capacity mobile IPCC systems

continued to be used throughout the 1960s

and 1970s, it was not until 1980s that the

larger capacity mines began to accept Semi-

Mobile IPCC systems as a concept for reducing

haulage costs to the mill.

Semi-Mobile In-Pit Crushing and Conveying

Semi-Mobile IPCC systems are designed to provide a relatively low cost solution

for mine plans that require relocating the equipment periodically, or for a mine


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plan involving satellite pit locations that cannot be economically mined if each

pit needed a separate stationary primary crushing system.

The Semi-Mobile Crushing concept gained momentum in the 1980s for several

reasons, including the capacity limitations of mobile plants available at the time,and the geometry of open pit hard rock mines that did not suit a mobile crusher

configuration. Due to substantial savings in civil work, Semi-Mobile Crushing

Plants were found to have a lower installed cost than stationary primary

crushing plants.

Semi-Mobile IPCC systems provide the flexibility to alter the primary crushing

location and conveying scheme as the mine is developed, or as the mining plan

changes. The frequency of relocating a Semi-Mobile IPCC system, as related to

the economic decision to use this type of equipment, is not an exact science. It is

more a function of the general mine plan that determines when the primary

crusher will need to be relocated at year 5 or at year 10, or perhaps at certain

periodic intervals over a 25 year period of a mines life.

Economic conditions can also influence the decision to use a Semi-Mobile IPCC

system, or cause changes in the mining plan that result in the requirement to

move a Semi-Mobile IPCC system to a different mine location based on ore grades

or deposit characteristics.

Once a decision to utilize a Semi-Mobile IPCC system is in place, it is a relatively

simple process to design the system.

The main elements to be considered when designing a Semi-Mobile IPCC system are:

The Pit Location for the Semi-Mobile Crushing Plant

The Semi-Mobile Crushing Plant

The Conveying System

The Pit Location for the Semi-Mobile IPCC system must provide easy access for the

haul trucks, and take into account the service requirements for the large pieces

of equipment in the system.

An operation with competent pit rock can

reduce the cost of the civil work required to

support the crushing plant to the point where

a Semi-Mobile IPCC system design, such as

shown here, can be installed with a minimum of

retaining wall or concrete structures.

Normally the crushing plant is placed on baserock or an engineered materials base, unless

the geotechnical characteristics of the

crushing plant site requires it to sit on a

concrete pad.

Other factors to be considered when choosing the site are the presence of local

geologic features, such as slip zones, water percolation issues, site drainage

issues, and of course insuring that you are not building your Semi-Mobile IPCC

system on ore that may need to be mined in the future.


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Semi-Mobile Crushing Plants are normally provided in one of several

configurations. The first configuration involves the haul truck dumping run of

mine ore directly into the crusher opening. This is typically accomplished withground supported truck pads, or with steel ramps as is pictured above.

When using a direct feed plant configuration, the volume of the crusher

discharge hopper and take away capacity of the discharge conveyor must be

designed to sufficiently accommodate the surge loading that can occur when the

haul truck dumps in a load of very fine material that chutes straight through to

the discharge hopper.

This issue can be minimized by the second configuration, using an inclined or

horizontal apron feeder to feed the crusher.

The apron feeder modulates the feed rate and allows the operator to control

feed rates when fines are present or when top-size boulders are fed into the

crusher. The choice between using a horizontal apron feeder or an inclined

apron feeder is influenced by available space and economic issues.

Most Semi-Mobile Crushing

Plants in the mining industry

use a 54, 60, or 63 class

gyratory crusher. Semi-

Mobile Crushing Plants with

large jaw crushers are in use

for applications handling up

to 8,000 tons per hour in iron

ore.

Very large roll crusherswith capacities up to 13,000

tons per hour, as shown in

this installation, are being

used in Semi-Mobile Crushing

Plants for the Canadian oil sands industry.

A consideration that cannot be overlooked is the dust collection or suppression

requirements required to meet the Department of Environmental Quality (DEC), or

other local regulations. The water volumes, on-board storage capacity, piping

requirements, and collection equipment to meet mandated particulate and opacity

requirements must be included in the Semi-Mobile Crushing Plant design. In

addition to layered dust suppression systems for the dump hopper and crusher

feed hopper, the dust collection system should include pickup points on the

crusher discharge conveyor at the crusher discharge hopper, at the end of the

discharge conveyor skirting, and at downstream conveyor transfer points.

The Conveying System routing is primarily determined by the mining plan, and

must accommodate normal mine traffic patterns, while achieving conveying grades

that are compatible with mobile service equipment. A conveyor design with

minimum of transfer points reduces the number of dust collection points in the

system.


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Fully Mobile In-Pit Crushing and Conveying

The Fully Mobile IPCC systems available today employ multiple pieces of track

mounted equipment with modern control systems that enable operating at the face

in overburden, hard rock, or coal.

During the past several years modern high capacity fully mobile IPCC systems,

with design capacities ranging from 3,000 to 12,000 tons per hour, have been

implemented for overburden, coal, and oil sands mining operations. These

systems are designed to operate at the face, and to take advantage of the capacity

and flexibility of the largest shovels commercially available today.

Designing a system that operates at these production levels, and that meet the

numerous site and geologic constraints, involves much more than just addressing

the type of crusher or type of conveyor to be used; it requires a completely

integrated approach and solution.

Identifying and examining the pieces of this puzzle is the first step to be taken

when developing an effective solution.

It has been our experience that the process of implementing an IPCC system,

particularly a fully mobile system, starts by blending the mines conceptual

vision with the mine planning functions required to mold that vision into a

working model that will realize the enormous economic and environmental

benefits available with an IPCC system.

So, what are the pieces of the puzzle that make up an IPCC system?

As a result of over 50 years experience with Semi-Mobile and Fully Mobile In-PitCrushing systems, we have defined a set of conditions that are needed for the

successful implementation of an IPCC system:

Knowledge of Mine Requirements

Mine Planning Analysis Capabilities

Analysis of the In-Pit Crushing and Conveying System Interfaces

Flexibility in Crusher Selection

Expertise in Designing In-Pit and Overland Conveying Systems

A Shared Knowledge and Acceptance of the Mine Requirements


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The shared understanding of why the mine is considering an IPCC system needs to

be accepted at all levels of the mining operation. This is a fundamental

requirement if the implementation of an IPCC system is to be successful.

The need to significantly reduce the cost of operation due to lower ore grades or

increased haul distances, the need to meet reductions in permitted dust and

exhaust particulate emissions, or the need to achieve reductions in CO emissions,

can be strategic reasons that translate into mine requirements.

CO reduction is becoming an important factor and the use of Semi-Mobile and

Fully Mobile IPCC systems offer the potential for substantial reductions in the

overall CO emissions for a mine property. It has been demonstrated that

employing a Semi-Mobile or Fully Mobile IPCC in a continuous mining system has

the potential to reduce mine CO emissions footprint by 50,000 to 150,000 tons per

year.

The acceptance of IPCC technologies within the mine organization as a whole is

another important criteria. The implementation of a conveyor haulage solution

first and foremost represents a significant cultural change from a truck

haulage solution. The conveyor haulage solution requires different equipment,

operating mentality, and maintenance procedures, challenging the mines ability

to adapt.

When a truck goes down in a truck-shovel operation, downtime is normally limited

to the time to affect a (relatively) quick repair, adjust the truck destination

schedules through the pits truck positioning software system, or bring up

another truck from the shop.

An IPCC system usually has one crusher, and one conveying system, so downtime

directly impacts production. This impact, from an operating and maintenanceperspective, needs to be planned and understood.

If the IPCC system is to be installed in a green field operation, this may not be a

major issue and the mine requirements can be geared towards the IPCC

requirements from the outset. Variables such as overburden or coal block sizes,

and associated volumes, can be designed to complement the advantages offered by

In-Pit Crushing and Conveying systems. This makes the next step, Mine Planning,

an easier exercise.

Adopting an IPCC system to replace a truck-shovel operation at an existing mine,

or to use in place of a truck-shovel operation in a part of the mine, requires

putting additional thought into the mine requirements. In particular, the blending

of a traditional truck & shovel mining plan with an IPCC mining plan requires

special sensitivities to where the two operations interface, or where there are

shared corridors of operation.

The hard factors that affect both mine planning and equipment selection are

another part of the mine requirement picture. These factors include:

Upstream mine operational availability requirements (drilling & blasting,

shovel operations, etc.)

Downstream process availability requirements


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Quarterly and annual production targets (TPH, YD3, M3, etc.)

Projected mine life

Selective mining requirements

IPCC availability targets

Power distribution requirements

Accurate overburden, coal, or ore interface measurements at depth

Geotechnical data (rock types, strata conformities or nonconformities,

etc.)

Overburden dump location requirements (inside or outside the pit)

Bank and loose material densities

Operating mine face lengths

Conveying distances to the next process location, or overburden dump area.

Haul road crossing requirements in a combined operation

Bench width and heights (initially, in 5 years, 10 years, etc.)

Number of cuts per bench Dust collection/suppression requirements

Mine Planning

Once the mine requirements are defined, the next piece to be looked at is mine

planning.

The IPCC system supplier should be working with the mine planning department so

that critical mine operating data is developed which allows the vendor to create a

3D IPCC mining plan or geological plan. There are a number of surface mine

software packages that can be used for this purpose including Surpac Vision by

Gemcom, MineSight

products by Mintec Inc., Vulcan by Maptek, and others.

Software modules within these programs that can be used include:

Pit Design (volume calculations, production plans, mine development) Block Modeling (grade or tonnage reports, based on bench data) Solid Modeling (geological, equipment models) Drill Hole Database Mine Scheduling

The mine planning step is crucial to establishing the basis for a cost effective

design of the IPCC system, understanding the geological situation, bench layouts,

mine access needs, the related mining methods, material handling requirements,

and the mining infrastructure to support an IPCC operation.

Equipment Selection

When the mine planning work is completed and the results evaluated, then the

next step in the process, equipment selection, can begin.

Once the mining plan has been developed, the unit operations of an IPCC system

are examined and evaluated. The typical unit operations include:


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The shovel (wire rope or hydraulic)

The crushing plant

The conveying system configuration

The stacking system (for overburden removal)

The above unit operations and all their interfacing characteristics must be

designed to meet the criteria of the pit layout and mining plan. Each unit

operation is as critical to the success of an IPCC operation as any other.

The Shovel

The wire rope or hydraulic shovel characteristics are one of the dominant

factors in determining mine bench characteristics and IPCC crushing plant

requirements.

A shovel will be more effective when working with a crushing plant at the face

because the shovel can load into the hopper in a more or less continuous motion

without the wait time that occurs while trucks are positioning or traveling to the

shovel location. This results in an increase in shovel capacity and greater

availability of the complete mining system.

Achieving these levels of production is dependent upon the shovel control system

software employed and the basic design chosen for the crushing plant.

The shovel bucket size determines the impact loads experienced by the crusher

hopper. Large capacity buckets can deliver a load exceeding 100 tons into thecrusher hopper, with single pieces of material weighing many tons. Since the

crusher dump hopper is located at some distance from the crawler structure

support point(s), the shovel load weight can result in substantial dynamic loads

for the carrying structure. If proper care is taken during the development of

the structural model and during the FEA calculations, the hopper does not need

to be ground supported.

It is important to choose an appropriate sized shovel for system operating

efficiency. The shovel must be able to dig the proposed block dimensions with the

required capacity. The shovel bucket capacity should not exceed the receiving

hopper capacity.

The shovel control system should be configured so that the basic movements of

the crushing plant can be controlled by the shovel operator. This will allow the

shovel operator to reposition the crushing plant as the shovel progresses along

the working face. The HMI display in the shovel should show numerous

annunciations so that the shovel operator is fully aware of the operating status

of the crushing plant and related equipment.

The Crushing Plant


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Selection of a track mounted crushing plant begins with a fundamental look at

the style of plant that matches the flexibility of the shovel, and meets the

production requirements of the mining plan.

Several basic questions to be addressed when considering the design for a fully

mobile crushing plant are:

Should a rigid superstructure or a slewing structure be selected?

If a rigid structure is selected, should it be mounted parallel or

perpendicular to the crawler tracks?

Should the discharge boom be designed to rotate?

These questions are critical to understanding how the crushing plant will

perform in terms of matching shovel capabilities, bench width requirements,

discharge conveyor boom configuration, ability to work multiple benches, and the

downstream conveying system.

The heart of the IPCC system, and the potential bottleneck in the system, is the

actual crusher. If the crusher struggles handling one type of material, or bogs

down with wet sticky material, design capacities will not be achieved.

Thus the crusher must be selected based on its ability to best meet all the

application factors associated with the type of material(s) to be crushed, material

strengths and breakage characteristics, material gradations, abrasiveness, and

the required crushing capacity.

The Fully Mobile IPCC systems being supplied today are typically designed to

operate with Double Roll Crushers or Sizers. A smaller 42 gyratory has been

used with a mobile crusher, and the use of larger gyratory crushers is receiving

some consideration. The crusher must be selected on its merits relative to theabove factors, just as it would be for a semi-mobile or stationary crushing plant.

An additional consideration is that shovel production is often measured in bank

cubic yards or cubic meters per hour, while crushing operations are typically

measured in tons per hour of loose material. Swell factor and breakage

characteristics of the material must be incorporated into the crusher selection

process, especially if the shovel is working with un-blasted material.

Addressing the above factors will generate a list of questions that need to be

evaluated when selecting the crusher type:

Can the crusher accept the largest expected feed size?

Can the crusher readily crush the feed material based on its compressivestrength?

Can the crusher produce suitable product for conveying at the desiredcapacity?

Does the crusher and downstream conveyors have sufficient capacity tohandle peak shovel loads?


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Does the crusher minimize the chance of plugging based on the materialcharacteristics?

Can the crusher be installed without requiring excessive structural costs?

Can the crusher safely pass un-crushable materials without damaging thecrusher?

Can the crusher process the material(s) with a reasonable HPhr/ton value?

Can the crusher process the material(s) with minimal abrasive wear costs?

Can the crusher operate economically without excessive maintenance costs?

Can the crusher provide a dependable and prolonged service life given thenature of the feed material?

Lets take a look at the characteristics for the two most popular types of

crushers used in high capacity IPCC systems today.

Double Roll Crushers utilize a relatively high speed (6-8 meters/second), lower

torque method to apply breaking energy to the rock. Comminution occurs from the

impact on the feed material by the crusher roll teeth and somewhat by the

pressure created against the material as it is drawn down between the rolls into

the gap. The rolls are equipped with rows of teeth staggered across the face of

the roll, which provide the crushing action as the material falls through the

rotating rolls. The gap between the rolls and the geometry / size / orientation of

the teeth determines product size.

The Double Roll Crusher is a good applicable for varied types of material.

They can work very well in soft materials, as well as in hard materials with

average compressive strengths of 100 to 120 MPa (15,000 to 17,000 psi), and

peak compressive strengths of 150 to 200 MPa (22,000 to 29,000 psi) due to

higher inertia generated by the flywheel and roll weights.

Similarly, Double Roll Crushers with their relatively fast circumferential

speed and relatively shorter teeth can handle sticky materials and wetter

materials well. The input (feed) size is determined both by the width of the

gap and the diameter of the roll. The ability of the Double Roll Crusher to

grab the feed material depends on the friction between feed and roll.

Crusher roll speed is also an important factor, and is designed to be equal, ornearly equal, to the speed of the feed material passing through the gap of the

rolls, which helps to minimize roll wear.

A main advantage of the Double Roll Crusher is its flexibility in handling

different materials to be crushed. This is a particular advantage when

crushing overburden with its wide range of material characteristics.

Another advantage is the Double Roll Crusher is equipped with a hydraulic

overload device, which allows one roll to move backwards so that the non-

crushable materials pass through the crusher.


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Sizers have been developed for soft to medium hard materials. They have two

rolls which counter-rotate into each other. The Sizer rolls are typically very

long compared to roll width, and when compared to a Double Roll Crusher,the Sizer utilizes a lower speed (2-3 meters/second), higher torque method of

applying the breaking energy to the rock.

A Sizer is a good solution for mixtures

of material where material strength is

generally in the 100 MPa (15,000

16,000 psi) range with occasional lumps

not exceeding 150 MPa (22,000 psi).

The feeding method for a Sizer,

pictured here, needs to be taken into

account, due to the roll length to

width ratio, to insure feed is deliveredto the full length of the roll so that

its capacity is effectively utilized.

While the Sizer provides a slightly

lower machine height, the feed opening area is the largest, which must be

considered in the plant design.

The distance (gap) between two teeth determines the output size of the

crusher. Tooth configurations are chosen to optimize the crushers

performance in a given application.

Aside from the ability to handle the required capacity, the key factors for

choosing a crusher type are the crushers ability to handle the top-size lumps,

and the ability to crush the maximum compressive strength material.

The Sizer can have more difficulty handling sticky material as it is more

susceptible to sticky material setting up between the teeth due to its relatively

slow speed, which can significantly reduce capacity.

In comparison to a Double Roll Crusher, the Sizer has fixed rolls and relieves

tramp iron or other un-crushable materials by reversing rotation of the rolls in

order to loosen the material blocking the rolls. If repeating this procedure

several times does not resolve the problem, the material blocking the Sizer needs

to be removed manually.

Comparing the Double Roll Crusher to the Sizer, the high energy crushing action

of the Double Roll Crusher produces a finer gradation that the Sizer which, as

its name implies, produces small sized chunks from large chunks.

Overland Conveying and Overburden Stacking Systems

The conveying scheme adopted for a particular IPCC application can be an involved

process, especially if it must adapt to an existing mines set of conditions.


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A typical IPCC conveying system will consist of the crushing plant discharge

conveyor, the face conveyor, and the overland conveyors transporting material to

the process plant or stockpiling area.

Additional conveying tools, including mobile transfer conveyors, bridge

conveyors, and inter-bench conveyors, are available to add to the conveying

systems flexibility.

Designing the conveying system becomes an exercise in blending the mine plan

requirements and available conveying equipment technology to achieve the

highest operational availabilities.

The goal when designing the conveying system is to use conveying elements that

are as long as possible. In addition to minimizing the number of transfer points,

longer conveyor lengths will decrease capital costs, increase belt life, and

decrease operating and maintenance costs for a given conveyor routing.

The conveying system design must

address system surge capacities,

transfer point considerations, and

relocation methods for the shiftable

conveyors. The most significant

downtime source with an IPCC

conveying system will occur when

shifting the face conveyor. The

shiftable conveying system (shown

here) for an overburden spreader

operation needs to be addressed in a

similar manner, since both sets of

conveyors basically move forward in parallel as the mining face progresses.

Focusing on an availability driven design for these two elements will reap large

benefits long term.

The frequency of shifting will be determined by the mining rate, bench

configuration, and the mining face length. Longer face lengths equate to fewer

relocations of the conveying equipment. Face lengths of up to 3 km are much more

optimal than 1 km or less, which would result in frequent conveyor position

changes and unacceptable availabilities.

Availability expectations must be adjusted to understand the initial and long term

availabilities of the system. The mine will experience a ramp up to target

availabilities with the shiftable conveyors that is directly related to the

learning curve for relocating the IPCC conveying system equipment. This is

normal and to be expected.

Shiftable conveyors are purpose designed to insure misalignment and the

inherent higher friction factors are taken into consideration. All the factors

affecting power and belt tension calculations must be included to insure under

sizing errors are avoided.

IPCC Systems - An Example


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Lets look at the development of the IPCC conveying system for a recent project.

The project required an IPCC system to handle 3,500 tons per hour of coal for a

mine using a shovel with a 28.5 m (37 yd) bucket.

The mine requirements and mine plan work determined the coal mining block sizes,

swell factors, the optimal bench width for the coal seam, and that it would

require 2 cuts to mine the coal seam with a single crushing plant.

An analysis of the coal crushing requirements, and potential for large frozen

lump sizes during winter conditions with temperatures down to minus 40 Celsius

pointed to the selection of a Double Roll Crusher.

The production rate was such that a dual track mounted crusher with a slew

bearing supported structure could be used to provide maximum flexibility between

the shovel and crushing plant.

Since this was the location of an existing mine with truck and shovel operations,

and the destination of the coal was a power plant several miles away, the design

of the conveying system needed to take into account the factors previously

mentioned.

A mobile transfer conveyor, shown in the following picture, was added between

the crushing plant and the shiftable conveyor to provide additional flexibility

and extend the period between relocations of the bench conveyor. The conveying

system was designed so that either a mobile transfer conveyor, as shown in the

following picture, or the crushing plants swivel discharge conveyor, could

discharge directly into the hopper car mounted on the shiftable conveyor.

This mine already had an existing pit, and since the IPCC system would beoperating at some depth within the pit, the conveying system pictured below was

designed using a number of different types of conveying equipment to facilitate

moving from one bench to the other, and then out of the pit with components

accommodating the mines terrain.


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Each mine will have its own unique aspects that need to be addressed. These might

include how many benches are required (now, in 5 years, in 10 years) for

overburden removal or ore extraction, how many cuts are required to take down

the coal bench, terrain restrictions when conveying the material out of the pit,

ground pressure limitations, overburden lay-down and reclamation requirements,

bridging of roads or waterways, and right-of-way issues for existing mine traffic.

With new fully mobile IPCC systems being supplied today for projects in Canada,Australia, and China, there are more and more reasons to consider this

technology as an alternative to traditional truck and shovel operations.

It is hoped that the information covered in this paper helps you understand the

pieces of the IPCC puzzle.

A puzzle that can be solved!

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ThyssenKrupp Tom Armesy - The IPCC Challenge Putting All the Pieces Together

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