Namaskar,

1. The problem with any stockpile design involves many individual issues.



a. the end use

b. commodity type

c. any tarping requirement

d. the commodity has a seasonal or year round end use

e. available surface area for said stockpile

f. work required if any for a base foundation, asphault, or drainage and

collection of leachate generated the commodity and its toxicity or damage to

surface waters.

g. whether it is a permanent stock yard-mine dedicated, or end use dedicated storage point

2. land area specific isssues

a. available square feet

b. ground conditions below the desired stockpile site requiring improvement for said commodity, tonnage planned or estimated per final design

c. desired method of reclaiming commodity being passive with a drawdown gallery or active using rubber tired machinery or tracked machinery

to feed a moveable belt feeder

d. commodity segregation if any with barriers if required to separate commodity sizes or its BTU value

e. is the stockpile for in bound material from an ocean or river berthing with eventual transfer to a second end user location by conveyor or rail

f. is the stock pile for out bound commodity by an ocean or river berth that may require transloading in or out of the port due

to draft limitations and tidal flows and year round availability of open water.

g. is the opportunity cost justified based on the commodities end use and available market or if it is seasonally dependent commodity?

h. is the funding for constrcution to come from actual capital net reserves or to be externally funded?

i. can the busness model tolerate the long term storage as production is delivered to it and have expandable capacity to reduce handling?

The stock pile stacking can be made simple with a high velocity material thrower from the ground surface eliminating any need for a

stacking conveyor, dedicated conveyor, stacking tube and create a conical stock pile with little effort or machinery for stacking creating the stock pile and its eventual angle of repose

or using the the material thrower to create a conical or radial stockpile from one location with little linear movement and less machinery for a friable

commodity.

A trapezoidal stockpile requires more work in preparation if a radial stacker is used alone as the stock pile sides must be created as the stockpile

grows and extends forward if the radial stacker is shorter in length than the stockpile width which creates issues with time and labor- increasing both and additional haulage

by truck in creating the side barrier to hold the material and create the angle of repose of said material.

A material thrower attached used at the end of a stacking conveyor or mounted on wheels can increase the stockpile capacity or reduce the number of movements required

or by itself reducing labor to an absolute minimum by the simple linear retreat of the conveyor as the stock pile grows forward.

A stock pile with less machinery=less labor=less cost=fewer mechanical issues and problems

Rubber tired machinery should not be used to climb stock piles under any circumstances as the material will shift and eventually

create a mass flow of material, injury, or death or fall over if the material is pushed up which is not required to begin with and which will

jeopardise the operator and potentially any person or vehicle near by as the material is not confined by any means other than gravitry

and the materials angle of repose and any resultant compaction of said material.

the algebra formulas for determining the

volume of cone and trapezoid are used to determine each volume times the weight of the commodity per cubic foot

The decision tree is the first and final answer for this issue and needs to be implemented before any other consideration based on the above issues and the ones I missed. ■

For the same capacities the cone will be cheaper but higher than the trapezoidal pile. There is nothing complex about calculating the volumes of either type of pile. ■

Dear Shri Somnath Kundu,

The stockpile type will depend upon capacity and also the cost of installation.

Conical stockpile: One can use a conical stockpile for limited storage capacity. Such a stockpile can be formed by simple means such as inclined belt conveyor and telescopic chute (if necessary). This will be the least expensive way of creating a stockpile. The stockpile formation should equally consider how to reclaim it. In such cases the reclaiming will be also very cheap like an in ground hopper, pay loader etc.

Trapezoidal stockpile: The trapezoidal stockpile is used when one wants to create a huge storage capacity. The stockpile can be made by linear travel stacker or stacker cum reclaimer. Such stockpile can be 400 or 500 m in length and storage in hundreds of thousands of tonnes (lacs of tonnes). Such system will be expensive. The reclaiming is also by linear travel reclaimer machine. If the trapezoidal upper edge is zero in length, then it becomes triangular cross section stockpile. The mathematical name for a trapezoidal stockpile is ‘prism having trapezoidal cross section’. The mathematical name for the triangular stockpile is ‘prism having triangular cross section’.

Stockpile capacity calculation: To be done as per the geometric formula applicable to the shapes. Refer to an engineering hand book for the formulae.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Pune, India.

Tel.: 0091 (0)20 25871916

Email: parimul@pn2.vsnl.net.in ■

Originally Posted by lzaharis

Namaskar,

1. The problem with any stockpile design involves many individual issues.



a. the end use

b. commodity type

c. any tarping requirement

d. the commodity has a seasonal or year round end use

e. available surface area for said stockpile

f. work required if any for a base foundation, asphault, or drainage and

collection of leachate generated the commodity and its toxicity or damage to

surface waters.

g. whether it is a permanent stock yard-mine dedicated, or end use dedicated storage point

2. land area specific isssues

a. available square feet

b. ground conditions below the desired stockpile site requiring improvement for said commodity, tonnage planned or estimated per final design

c. desired method of reclaiming commodity being passive with a drawdown gallery or active using rubber tired machinery or tracked machinery

to feed a moveable belt feeder

d. commodity segregation if any with barriers if required to separate commodity sizes or its BTU value

e. is the stockpile for in bound material from an ocean or river berthing with eventual transfer to a second end user location by conveyor or rail

f. is the stock pile for out bound commodity by an ocean or river berth that may require transloading in or out of the port due

to draft limitations and tidal flows and year round availability of open water.

g. is the opportunity cost justified based on the commodities end use and available market or if it is seasonally dependent commodity?

h. is the funding for constrcution to come from actual capital net reserves or to be externally funded?

i. can the busness model tolerate the long term storage as production is delivered to it and have expandable capacity to reduce handling?

The stock pile stacking can be made simple with a high velocity material thrower from the ground surface eliminating any need for a

stacking conveyor, dedicated conveyor, stacking tube and create a conical stock pile with little effort or machinery for stacking creating the stock pile and its eventual angle of repose

or using the the material thrower to create a conical or radial stockpile from one location with little linear movement and less machinery for a friable

commodity.

A trapezoidal stockpile requires more work in preparation if a radial stacker is used alone as the stock pile sides must be created as the stockpile

grows and extends forward if the radial stacker is shorter in length than the stockpile width which creates issues with time and labor- increasing both and additional haulage

by truck in creating the side barrier to hold the material and create the angle of repose of said material.

A material thrower attached used at the end of a stacking conveyor or mounted on wheels can increase the stockpile capacity or reduce the number of movements required

or by itself reducing labor to an absolute minimum by the simple linear retreat of the conveyor as the stock pile grows forward.

A stock pile with less machinery=less labor=less cost=fewer mechanical issues and problems

Rubber tired machinery should not be used to climb stock piles under any circumstances as the material will shift and eventually

create a mass flow of material, injury, or death or fall over if the material is pushed up which is not required to begin with and which will

jeopardise the operator and potentially any person or vehicle near by as the material is not confined by any means other than gravitry

and the materials angle of repose and any resultant compaction of said material.

the algebra formulas for determining the

volume of cone and trapezoid are used to determine each volume times the weight of the commodity per cubic foot

The decision tree is the first and final answer for this issue and needs to be implemented before any other consideration based on the above issues and the ones I missed.

Dear sir

In thermal power plant in India

1) What shall be the maximum width of coal stockpile ? . Is there any engineering criteria to determine the same

2) Due to space constraint , i intend to inch the height of coal stockpile to 12mtr instead of 10mtr . Now as apprehended by you there is likelihood of spontaneous firing . If i understand correctly spontaneous firing is attributed to build up heat at below region of coal stockpile due to height . Please correct me with my understanding . If iam right then what shall be the maximum i should limit to refrain spontaneous firing ? ■

Originally Posted by guddu

Dear sir

In thermal power plant in India

1) What shall be the maximum width of coal stockpile ? . Is there any engineering criteria to determine the same

2) Due to space constraint , i intend to inch the height of coal stockpile to 12mtr instead of 10mtr . Now as apprehended by you there is likelihood of spontaneous firing . If i understand correctly spontaneous firing is attributed to build up heat at below region of coal stockpile due to height . Please correct me with my understanding . If iam right then what shall be the maximum i should limit to refrain spontaneous firing ?

Namaskar Guddu,

Greetings and salutations, I hope the weather is treating you and the sub continent well.

The issues with stock piles of steam coal are all encompassing with basic house keeping

and vigilence with regard to the possible hot spots that may develop in the coal stockpile

over time due simply from the steam coals friability.

Ideally you want to be able to stockpile to have enough steam coal to prevent shortages

due to earthquakes, ship losses, labor strikes, weather related transportation issues, and

our mutual concern regarding monsoons, flooding, and railway trackage losses.

About Issue Number 1; The coal stockpile can be as wide as you desire and it needs to be

stable enough to use earth movers to push the steam coal to a reclaim area if earthmovers

are used in combination with below ground level drawpoints.

The wider a pile is at the crown the more stable the mass simply from natural compaction,

machine compaction and gravity. the more rain you have the greater the compaction simply from

the rainpassing through the pile top and sides washing the dust down and allowing the coal chunks

to slide against each other and pack further like sands and gravels.

About Issue Number 2; The faster the steam coal is moved out to the burners the better to

reduce the chance of spontaneous combustion from off gassing and heat. You can not deal

with a fire in the coal until you know you have one, or you see a lightning strike on the stockpile.

Your available area for the stockpile is the primary issue and if you can have multiple piles it

limits the exposure of the entire coalstocks to a fire from spontaneous combustion due to off

gassing and heat and the ugly lightning strikes that will cause a lot of fires in the line of the

bolts striking path along the pile.

If you can make use of multiple pilings without compromising the efficiency of the

below ground drawpoint if used all the better. ■

Originally Posted by lzaharis

Namaskar Guddu,

Greetings and salutations, I hope the weather is treating you and the sub continent well.

The issues with stock piles of steam coal are all encompassing with basic house keeping

and vigilence with regard to the possible hot spots that may develop in the coal stockpile

over time due simply from the steam coals friability.

Ideally you want to be able to stockpile to have enough steam coal to prevent shortages

due to earthquakes, ship losses, labor strikes, weather related transportation issues, and

our mutual concern regarding monsoons, flooding, and railway trackage losses.

About Issue Number 1; The coal stockpile can be as wide as you desire and it needs to be

stable enough to use earth movers to push the steam coal to a reclaim area if earthmovers

are used in combination with below ground level drawpoints.

The wider a pile is at the crown the more stable the mass simply from natural compaction,

machine compaction and gravity. the more rain you have the greater the compaction simply from

the rainpassing through the pile top and sides washing the dust down and allowing the coal chunks

to slide against each other and pack further like sands and gravels.

About Issue Number 2; The faster the steam coal is moved out to the burners the better to

reduce the chance of spontaneous combustion from off gassing and heat. You can not deal

with a fire in the coal until you know you have one, or you see a lightning strike on the stockpile.

Your available area for the stockpile is the primary issue and if you can have multiple piles it

limits the exposure of the entire coalstocks to a fire from spontaneous combustion due to off

gassing and heat and the ugly lightning strikes that will cause a lot of fires in the line of the

bolts striking path along the pile.

If you can make use of multiple pilings without compromising the efficiency of the

below ground drawpoint if used all the better.

Dear Mr lzaharis

Thanks for your generosity

1) Emphatically , you have recomended to have the multiple stockpile to avoid sponteneous firing . Now what shall be critiria to decide no of pile . For eg , i have to stock the coal conveying capacity of 486 TPH for 30 days , which yields = 349200T of coal storage capacity . Now having this parameter , how do i optimize the no of pile and with what height

2) What is mean by "off gassing and heat and the ugly lightning strikes " which causes sponteneous firing ?

3) For a given storage capacity of stockpile , How to determine the maximum height to avoid sponteneous firing ? . Any formula or derivation will highly be appreciable

4) As per general engineering practice , how to decide no of deck plate in belt conveyor technical structure support for a given length . For eg : i conveyor length is 600mtr with carrying and return , now how do i decide no of deck plate for idler?

awaiting for your response ■

Originally Posted by guddu

Dear Mr lzaharis

Thanks for your generosity

1) Emphatically , you have recomended to have the multiple stockpile to avoid sponteneous firing . Now what shall be critiria to decide no of pile . For eg , i have to stock the coal conveying capacity of 486 TPH for 30 days , which yields = 349200T of coal storage capacity . Now having this parameter , how do i optimize the no of pile and with what height

2) What is mean by "off gassing and heat and the ugly lightning strikes " which causes sponteneous firing ?

3) For a given storage capacity of stockpile , How to determine the maximum height to avoid sponteneous firing ? . Any formula or derivation will highly be appreciable.

4) As per general engineering practice , how to decide no of deck plate in belt conveyor technical structure support for a given length . For eg : 1 conveyor length is 600mtr with carrying and return , now how do i decide no of deck plate for idler?

awaiting for your response

350,000 tons for 30 days storage

50,000 tons for a buffer amount

400000 tons total est.

1. 4 conical stockpiles 350-feet in diameter and 100-feet tall would create 119,000 tons of storage

per stockpile(rounded) 472,000 tons total (rounded) for four stockpiles.

You would need a material thrower under the tripper that rotates to maximise the storage capacity

of the cones as gravity will not. work well using a tripper alone as the cola storage would be limited

to the cone height created under the tripper and conveyor.



At a consumption rate of 12,000 tons per day the single conical stockpile will only last 10 days (rounded)

8 conical stockpiles 265-feet in diameter, 100-feet high would create 68,300 cubic yards of storage

per stockpile eqauling 546,400 cubic yards. In using 52 pounds per cubic foot gives us 383,572 tons

of steam coal

12 conical stockpiles 106 feet in diameter 40 feet high creates 4,370 cubic yards per stockpile,

creating 3,067 tons per stockpile(rounded), 36,813 tons in total.

2. Of gassing refers to the naturally occuring emmisions of sulphur and other compounds in coal and some plastics.

some coals have tendency to spontaneosly combust as they are very friable and break easily.

There is no magic bullet involved in stockpile height with relation to lighning strikes as local weather will determine the

number of lightning storms.

3. The issue of spontaneous combustion is reduced with simple housekeeping and vigilance with regard to dust control and

cleaning up dust spills to prevent fires.

4 You can purchase steel supported conveyor stands/frames to eliminate the need for deck plating and it makes training the belt

easier as well. ■

Originally Posted by lzaharis

350,000 tons for 30 days storage

50,000 tons for a buffer amount

400000 tons total est.

1. 4 conical stockpiles 350-feet in diameter and 100-feet tall would create 119,000 tons of storage

per stockpile(rounded) 472,000 tons total (rounded) for four stockpiles.

You would need a material thrower under the tripper that rotates to maximise the storage capacity

of the cones as gravity will not. work well using a tripper alone as the cola storage would be limited

to the cone height created under the tripper and conveyor.



At a consumption rate of 12,000 tons per day the single conical stockpile will only last 10 days (rounded)

8 conical stockpiles 265-feet in diameter, 100-feet high would create 68,300 cubic yards of storage

per stockpile eqauling 546,400 cubic yards. In using 52 pounds per cubic foot gives us 383,572 tons

of steam coal

12 conical stockpiles 106 feet in diameter 40 feet high creates 4,370 cubic yards per stockpile,

creating 3,067 tons per stockpile(rounded), 36,813 tons in total.

2. Of gassing refers to the naturally occuring emmisions of sulphur and other compounds in coal and some plastics.

some coals have tendency to spontaneosly combust as they are very friable and break easily.

There is no magic bullet involved in stockpile height with relation to lighning strikes as local weather will determine the

number of lightning storms.

3. The issue of spontaneous combustion is reduced with simple housekeeping and vigilance with regard to dust control and

cleaning up dust spills to prevent fires.

4 You can purchase steel supported conveyor stands/frames to eliminate the need for deck plating and it makes training the belt

easier as well.

Dear Mr lzaharis

1) Referring to above stockpile capacity , if i were to determine the geometrical dimension of stockpile in trapezoidal case , then what shall be the maximum height of stockpile .

2) Does the , Of gassing , contributes in spontaneous firing and how?

3) I still could not conceive , why the height of coal stockpile is being restricted to maximum 10.9mtr . Primarly it is because of spontenous firing which is occur to to non ventilation at bottom portion of pile . Would you please explain in terms of some mathematical expression for relation between stockpile height and spontenous firing . ?

thanks ■

In regard to question number one it wil depend entirely on

the available square area you can set aside to create the base

for the trapezoidal stockpile only.

The stockpile height is limited in scope simply because of the available

stacking conveyor machinery used and its actual reach; by this I mean

the available arc created by the stacker drive tires which limits the

stackers dumping range.

A material stacker could be employed to make a narrow trapezoidal pile in

a simple fan dumping method without the use of wings in the first place and the

stockpile would be longer in length and of course narrower in width.

The narrow width of a fan stockpiled method trapezoid would limit the amount

of area that the small earth mover can push the material and place it.

In our case the stockpile edges were created by making wings of dumped

material one dumping lorry high.

The stacker was allowed to travel in its limited arc from one side to the

other filling in the area between the wings of material dumped on the edges

which acted a captive retaining method to hold the stockpile inplace and

create the angle of repose which was twenty one degrees for halite.

The rain water diversion gutters also aided in keeping the stockpile edges in place

maintaining the low angle repose being twenty one degrees.

Capacity was added to the stockpile by employing a small finish dozer to push the

halite that was dumped in one front corner where a bench was created to dump the

material to allow the dozer to push the material to the furthest ends of the existing

stockpile to add capacity of the finished trapezoidal pile adding both height and

tonnage in the process to the to create 125,000 tons of halite in each stockpile

in an square area that was created for a trapezoidal stockpile ment for 100,000

tons of halite originally.

a) the other issue which is a very wet cricket pitch is the angle of

repose of the steam coal to be used as the lower the angle of

repose the the lower the horizon of the stockpile and the

lower tonnage capacity which will have to be over come by

increasing the size of the stockpiles base square area to increase

the stockpile tonnage.

Issue number two is related to the friability of the steam coal which relates to

the actual hardness of the coal mined if it is easily breakable the more area of the

coal lumps are exposed to the earths atmospere which provides the 21 percent

oxygen that aids in spontaneos combustion.

It also has to do with any oils or greases left by the mining machinery that will drip

and fall on the coal as it is mined and transported from the mine face.

The sub-bituminuos coals mined in the Powder River Basin in the States of Wyoming and

Montana in the United States are a very friable coal as it is very young in geologic age and it

requires quick handling and transport to the end user as it has a nasty habit of catching

fire if it is left to long in stockpiles waiting to be loaded into the unit trains/rakes of coal wagons.

The younger in geologic age that a steam coal being mined is less dense and less strong it is in

the actual sedimentary nature of the coal and it is much weaker and the layers of coal will break more easily exposing more surface area to the surrounding air increasing the posssibility

of spontaneos combustion, the indonesian coals being mined now are no different.

The smaller the actual square area of a coal stockpile, the less exposure to a possible

lightning strike you have to contend with.

With trapezoidal stockpile you have five exposed rectangular sides.

With a right cone that is 350 feet in diameter and one hundred feet high you have

a side which is 202 feet long(rounded) and 30 degrees which may not hold its angle

and slide further creating a larger cone at a lower angle of repose.

The volume is 3,200,074.306 cubic feet times 30 pounds equals 96,002,229.17 pounds

or 48,001.11458 tons of coal and with you cosumption rate it will last 4 days at this rate

of consumption.

You would need 8 stockpiles of this size as mentioned earlier.

The implementation of a mobile material thrower with tripper negates any issues of

storage volume as the thrower will simply cricket bat the coal to the edge and the

edge will continue to build until the thrower can no longer over come the height

created by the thrower until the pile is reclaimed.

A stationary belt with a tripper mechanism feeding a high tonnage material thrower

could be used to create a rectangular fan stockpile as well without a mobile radial stacker

if one desired to do so and a 48 inch conveyor would be required for continuos delivery. ■

Originally Posted by I G Mulani

Dear Shri Somnath Kundu,

The stockpile type will depend upon capacity and also the cost of installation.

Conical stockpile: One can use conical stockpile for limited storage capacity. Such stockpile can be formed by simple means such as inclined belt conveyor and telescopic chute (if necessary). This will be the cheapest way of creating stockpile. The stockpile formation should equally consider how to reclaim it. In such cases the reclaiming will be also very cheap like a ground hopper, pay loader etc.

Trapezoidal stockpile: The trapezoidal stockpile is used when one wants to create a huge storage capacity. The stockpile can be made by linear travel stacker or stacker cum reclaimer. Such stockpile can be 400 or 500 m in length and storage in hundreds of thousands of tonnes (lacs of tonnes). Such system will be expensive. The reclaiming is also by linear travel reclaimer machine. If the trapezoidal upper edge is zero in length, then it becomes triangular cross section stockpile. The mathematical name for trapezoidal stockpile is ‘prism having trapezoidal cross section’. The mathematical name for the triangular stockpile is ‘prism having triangular cross section’.

Stockpile capacity calculation: To be done as per the geometric formula applicable to the shapes. Refer engineering hand book for the formulae.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Pune, India.

Tel.: 0091 (0)20 25871916

Email: parimul@pn2.vsnl.net.in

Dear Kundu,

My experience is with Iron Ore and Coal Stacking in Ports (About 40 Years in Ports),

Since your question is simple,

The answer is that, We always go for trapezoidal Stacking.The Bulk Stacking (upto 5500TPH) is done by either stacker or Stacker cum Reclaimer.

Due to poor ground condition height of stack is restricted.Normally 10 mtrs,but with better ground improvement up to 15 mtrs height is also done.

Since it is either for Ship loading or Ship unloading at least one ship load cargo of the same grade has to be stocked.

Trapezoidal stack gives better out put with Stacker Reclaimers while loading.

For coal stock,expecially thermal coal, approach for fire fighting is essential.

The stockyard capacity calculation is a complex issue due to various factors.

Rgds,

Narayanan Nalinakshan. ■

Originally Posted by NarayananNalinakshan

Dear Kundu,

My experience is with Iron Ore and Coal Stacking in Ports (About 40 Years in Ports),

Since your question is simple,

The answer is that, We always go for trapezoidal Stacking.The Bulk Stacking (upto 5500TPH) is done by either stacker or Stacker cum Reclaimer.

Due to poor ground condition height of stack is restricted.Normally 10 mtrs,but with better ground improvement up to 15 mtrs height is also done.

Since it is either for Ship loading or Ship unloading at least one ship load cargo of the same grade has to be stocked.

Trapezoidal stack gives better out put with Stacker Reclaimers while loading.

For coal stock,expecially thermal coal, approach for fire fighting is essential.

The stockyard capacity calculation is a complex issue due to various factors.

Rgds,

Narayanan Nalinakshan.

Namaskar Narayanan Nalinakan,

The problem is we have no idea what the possible

and actually available square area is involved in this

potential steam plant as it does not exist apparently.

The issue is not simple by any means, as stockpiling

will occur/must occur during drawdown.

And again we have no idea of any kind what existing

square area there may be or may not be available

at this site, as apparently it is limited in square area

according to the responses given.

Having a stock yard with five filled conical piles of the size

119-20 thousand tons per stockpile and using the fifth

stockpile to be left as the simple buffer to allow one conical

pile to be reclaimed by what ever methodology is employed

while the fifth one is in actual reserve to be used while one

of the 4 primary conical stockpiles is being reclaimed allowing

the coal to be used and removed in a timely manner reducing

the opportunity for spontaneous combustion from a lightning

strike or a smoldering fire in coal pile.

A set of five conical stockpiles filled with a tripper/material

thrower would allow better control of inventory by limiting

the age of the steam coal in the five piles and not allowing

it to become so old it could become a fire hazard from a

lightning strike or a fire occuring in one of the other 4 piles.

The conical piles could be constructed with partial silo walls to

contain the piles at the 350 foot diameter which would allow the

tripper operator to slow down the operating speed the material

thrower as the pile is being filled against the silo hip walls which is

a defined area which would also allow easy clean up with small tractor

with a sweeper attachment when the stockpile is emptied prior to

the stockpile being refilled by the tripper and material thrower

while the following pile is being reclaimed in a 1-2-3-4-5 sequence.

The other issue is fire control and the design of the conical pile

and linear location of the 5 piles would allow the simple

plumbing and placement of water cannons along the tripper cat

walk wherein the fire cannons could quickly douse a fire if it

occurs in specific stockpile preventing the spread to the adjoining

piles.

Finally, we also have no knowledge of the siting or the topography

or even the location of this supposed steam plant which is the primary

issue here.

Ideally the five conical stockpiles will be filled prior to start up.

Stockpile one is used for one week and then stock pile two is reclaimed and

clean up of stockpile one is completed and then the number one stock pile is

is refilled for one weeks burn.

Continuing; stockpile two is reclaimed as stockpile one is being refilled,

stockpile two is emptied and cleanup commences of stockpile two.

By this time stockpile one is filled in a seven day period.

After cleanup stockpile two is refilled over a seven day period while stockpile three is reclaimed.

Stockpile two is refilled over seven days.

Stockpile three is emptied and cleaned as stockpile four is reclaimed.

Stockpile 3 is refilled as stockpile 4 is reclaimed.

Stockpile 3 is refilled over seven days.

Stock pile 4 is emptied and cleaned as stockpile five is reclaimed.

The process begins again with stockpile number 1 as stockpile number

five is cleaned and is refilled over seven days.

The reclaiming is complete and stockpile housekeeping is maintained

every 35 days reducing any coal fire risk to a bare minimum by the

plant operator only exposing a bare minimum of stockage inventory

to any fire exposure.

A trapezoidal stockpile has no real method of inventory control unless the

stockpile is reclaimed in mass and refilled in mass leaving old stocks in

the pile increasing the possibility of spontaneos combustion of the trapezoidal

stockyard affecting the entire stockyard mass. ■

Originally Posted by lzaharis

In regard to question number one it wil depend entirely on

the available square area you can set aside to create the base

for the trapezoidal stockpile only.

The stockpile height is limited in scope simply because of the available

stacking conveyor machinery used and its actual reach; by this I mean

the available arc created by the stacker drive tires which limits the

stackers dumping range.

A material stacker could be employed to make a narrow trapezoidal pile in

a simple fan dumping method without the use of wings in the first place and the

stockpile would be longer in length and of course narrower in width.

The narrow width of a fan stockpiled method trapezoid would limit the amount

of area that the small earth mover can push the material and place it.

In our case the stockpile edges were created by making wings of dumped

material one dumping lorry high.

The stacker was allowed to travel in its limited arc from one side to the

other filling in the area between the wings of material dumped on the edges

which acted a captive retaining method to hold the stockpile inplace and

create the angle of repose which was twenty one degrees for halite.

The rain water diversion gutters also aided in keeping the stockpile edges in place

maintaining the low angle repose being twenty one degrees.

Capacity was added to the stockpile by employing a small finish dozer to push the

halite that was dumped in one front corner where a bench was created to dump the

material to allow the dozer to push the material to the furthest ends of the existing

stockpile to add capacity of the finished trapezoidal pile adding both height and

tonnage in the process to the to create 125,000 tons of halite in each stockpile

in an square area that was created for a trapezoidal stockpile ment for 100,000

tons of halite originally.

a) the other issue which is a very wet cricket pitch is the angle of

repose of the steam coal to be used as the lower the angle of

repose the the lower the horizon of the stockpile and the

lower tonnage capacity which will have to be over come by

increasing the size of the stockpiles base square area to increase

the stockpile tonnage.

Issue number two is related to the friability of the steam coal which relates to

the actual hardness of the coal mined if it is easily breakable the more area of the

coal lumps are exposed to the earths atmospere which provides the 21 percent

oxygen that aids in spontaneos combustion.

It also has to do with any oils or greases left by the mining machinery that will drip

and fall on the coal as it is mined and transported from the mine face.

The sub-bituminuos coals mined in the Powder River Basin in the States of Wyoming and

Montana in the United States are a very friable coal as it is very young in geologic age and it

requires quick handling and transport to the end user as it has a nasty habit of catching

fire if it is left to long in stockpiles waiting to be loaded into the unit trains/rakes of coal cars.

The younger in geologic age that a steam coal being mined is less dense and less strong in

the actual sedimentary nature of the coal is much weaker and the layers of coal will break

more easily exposing more surface area to the surrounding air increasing the posssibility

of spontaneos combustion, the indonesian coals being mined now are no different.

The smaller the actual square area of a coal stockpile, the less exposure to a possible

lightning strike you have to contend with.

With trapezoidal stockpile you have five exposed rectangular sides.

With a right cone that is 350 feet in diameter and one hundred feet high you have

a side which is 202 feet long(rounded) and 30 degrees which may not hold its angle

and slide further creating a larger cone at a lower angle of repose.

The volume is 3,200,074.306 cubic feet times 30 pounds equals 96,002,229.17 pounds

or 48,001.11458 tons of coal and with you cosumption rate it will last 4 days at this rate

of consumption.

You would need 8 stockpiles of this size as mentioned earlier.

The implementation of a mobile material thrower with tripper negates any issues of

storage volume as the thrower will simply cricket bat the coal to the edge and the

edge will continue to build until the thrower can no longer over come the height

created by the thrower until the pile is reclaimed.

A stationary belt with a tripper mechanism feeding a high tonnage material thrower

could be used to create a rectangular fan stockpile as well without a mobile radial stacker

if one desired to do so and a 48 inch conveyor would be required for continuos delivery.

Dear Mr lzaharis

1) With regard to limitation of height for trapezoildal coal stockpile , my understanding is that the height is limited to maximum 10 mtr primarily because of no ventilation at bottom portion of coal which will create heat . I dont know whether iam right in my perception , but would request you to please audment me with my understanding . Indeed the available stacking conveyor machinery could be the part of concern , but dont you think we can increase the luffing angle of stacker recliamer to suit the system design .

2) To make better understanding , i would like your attention that other than machinery construction limitation , is there any other specific concern why cant we go for height beyond 10mtr

3) What is measurement of friability of coal . Is there any guideline to be followed to categorize the friability of coal ?

4) How does of gassing (emission of sulpher) contributes to spontaneous firing ?

5) Little bit different from subject ,how to decide the chute dimensions in coal conveyor feeding point ? Would you please forward or attach any guideline or handbook ■

Originally Posted by guddu

Dear Mr lzaharis

1) With regard to limitation of height for trapezoidal coal stockpile , my understanding is that the height is limited to maximum 10 mtr primarily because of no ventilation at bottom portion of coal which will create heat . I dont know whether iam right in my perception , but would request you to please augment me with my understanding . Indeed the available stacking conveyor machinery could be the part of concern , but dont you think we can increase the luffing angle of stacker recliamer to suit the system design .

2) To make better understanding , i would like your attention that other than machinery construction limitation , is there any other specific concern why cant we go for height beyond 10mtr

3) What is measurement of friability of coal . Is there any guideline to be followed to categorize the friability of coal ?

4) How does of gassing (emission of sulpher) contributes to spontaneous firing ?

5) Little bit different from subject ,how to decide the chute dimensions in coal conveyor feeding point ? Would you please forward or attach any guideline or handbook

==================================================================================================== ==============================================================================

Namaskar Guddu,

On your point number one:

The issue of stockpile height relates to the steam plants need for coal,

its net burning requirements and the equipment available useable to

reclaim and stack the steam coal.

Any stockpile has to be sized within a given foot print and the steam

plants combustion needs for X period.

The local steam plant carries enough excess capacity for 90 days of

uninterrupted burn which is 100 tons per hour 2,400 tons per day,

16,800 tons peer week, 67,200 tons per 28 days, 204,000 tons excess

buffer capacity for ninety days(rounded)in case of a system wide disaster,

mine labor strikes, railroad worker strikes and a "Force Majour" that may

be invokeed by the railway company in the event of a railway disaster such

as flooding or an earthquake or snow storm affecting its right of ways.

The power plant near here in the example uses a single fourty eight inch conveyor

belt which is fed by twin opposing apron feeders under a rotary tippler which has

been flawless since its installation in 1945.

The fourty eight inch conveyor belt exits the dumping pit which is secured below

the lakes water level in bedrock.

The conveyor consists of one flight of a steel supported troughed belt wherein it is

tower mounted using a mechanical counter weight for the conveyor and the idlers

are of the steel supported type. The entire conveyor flight iis housed ina steel skin

with a walkway for shoveling and inspection of the conveyor to the dumping point

at the stockpiles horizon. The discharge structure and head pulley is supported and

suspended by wire rope secured to the conveyors second support tower.

The construction of the coal dumping station in relation to the to the position of the

steam station is such that the the stockpile is anchored into the side of a hill near the

lakeshore. The coal drawpoint and the single roll crusher are buried in the bottom

of the coal pile wherea an excavation and concrete box structure was created for the

dumping hopper, diverter gate and the single roll crusher/sizer.

The coal pile is set up as a passively fed coal pile using an earthmover with a wide

blade to push the coal into the mouth of the chute feeding the single roll crusher.

There is a diverter gate chute above the roll crusher which allows the pile to reclaimed from

the left of right side of the stockpile mound to maintain pile stability and ease in pushing.

When the steam coal is delivered and dumped on the stockpile the earth mover simply waits until

one railwagon is fully dumped from the tippler and the entire load is pushed to the edge of the

stockpile and the earth mover returns to the dumping point and repeats the process until the

rake is discharged.

The same dozer will also reclaim the older coal while it is moving the newly delivered coal to the edge

of the stockpile to maintain inventory control. at some poilt a second earthmover may be used when

stacking coal to increase storage capactiy by creating a larger bench works for coal strockage in the fall

months for the steam stations winter time steam needs wher 40,000 tons per week may be delivered to

add to the stockpile to prevent shortages.

On point number two:

A higher stockpile requres more work and larger machinery and the cost effectiveness of the machinery

becomes an issue for the operator wherein:

The stockpile or piles are limited to the available square area of the Plant site that is not used for the

steam plant and its support facilities as you need room for the support machinery, water treatment,

sewage treatment, locomotive shops, fossil fuel storage for the burners, repair and rebuild shops

dozer shops, roadways as well as parking lots and any dock facilities along a shoreline.

On point number 3:

The friability of coal refers to its ease in being broken/breakage/ Rockwell or Mohs hardeness.

On point number 4:

Sulphur in its solid form is combustable and where sulphur is composed of carbon and other

volatile organic compounds which occur naturally in coal of all types and will aid in spontaneos

combustion due to it volatile organic compounds and carbon which is younger in geologic age.

With regard to the design of conveyor chutes you can contact Mr. Larry Nordell via the web site here and the

Conveyor Equipment Manufacturing Association www.cema.org or the

Vibrating Screen Manufacturers Association www.vsma.org ■

Originally Posted by lzaharis

==================================================================================================== ==============================================================================

Namaskar Guddu,

On your point number one:

The issue of stockpile height relates to the steam plants need for coal,

its net burning requirements and the equipment available useable to

reclaim and stack the steam coal.

Any stockpile has to be sized within a given foot print and the steam

plants combustion needs for X period.

The local steam plant carries enough excess capacity for 90 days of

uninterrupted burn which is 100 tons per hour 2,400 tons per day,

16,800 tons peer week, 67,200 tons per 28 days, 204,000 tons excess

buffer capacity for ninety days(rounded)in case of a system wide disaster,

mine labor strikes, railroad worker strikes and a "Force Majour" that may

be invokeed by the railway company in the event of a railway disaster such

as flooding or an earthquake or snow storm affecting its right of ways.

The power plant near here in the example uses a single fourty eight inch conveyor

belt which is fed by twin opposing apron feeders under a rotary tippler which has

been flawless since its installation in 1945.

The fourty eight inch conveyor belt exits the dumping pit which is secured below

the lakes water level in bedrock.

The conveyor consists of one flight of a steel supported troughed belt wherein it is

tower mounted using a mechanical counter weight for the conveyor and the idlers

are of the steel supported type. The entire conveyor flight iis housed ina steel skin

with a walkway for shoveling and inspection of the conveyor to the dumping point

at the stockpiles horizon. The discharge structure and head pulley is supported and

suspended by wire rope secured to the conveyors second support tower.

The construction of the coal dumping station in relation to the to the position of the

steam station is such that the the stockpile is anchored into the side of a hill near the

lakeshore. The coal drawpoint and the single roll crusher are buried in the bottom

of the coal pile wherea an excavation and concrete box structure was created for the

dumping hopper, diverter gate and the single roll crusher/sizer.

The coal pile is set up as a passively fed coal pile using an earthmover with a wide

blade to push the coal into the mouth of the chute feeding the single roll crusher.

There is a diverter gate chute above the roll crusher which allows the pile to reclaimed from

the left of right side of the stockpile mound to maintain pile stability and ease in pushing.

When the steam coal is delivered and dumped on the stockpile the earth mover simply waits until

one railwagon is fully dumped from the tippler and the entire load is pushed to the edge of the

stockpile and the earth mover returns to the dumping point and repeats the process until the

rake is discharged.

The same dozer will also reclaim the older coal while it is moving the newly delivered coal to the edge

of the stockpile to maintain inventory control. at some poilt a second earthmover may be used when

stacking coal to increase storage capactiy by creating a larger bench works for coal strockage in the fall

months for the steam stations winter time steam needs wher 40,000 tons per week may be delivered to

add to the stockpile to prevent shortages.

On point number two:

A higher stockpile requres more work and larger machinery and the cost effectiveness of the machinery

becomes an issue for the operator wherein:

The stockpile or piles are limited to the available square area of the Plant site that is not used for the

steam plant and its support facilities as you need room for the support machinery, water treatment,

sewage treatment, locomotive shops, fossil fuel storage for the burners, repair and rebuild shops

dozer shops, roadways as well as parking lots and any dock facilities along a shoreline.

On point number 3:

The friability of coal refers to its ease in being broken/breakage/ Rockwell or Mohs hardeness.

On point number 4:

Sulphur in its solid form is combustable and where sulphur is composed of carbon and other

volatile organic compounds which occur naturally in coal of all types and will aid in spontaneos

combustion due to it volatile organic compounds and carbon which is younger in geologic age.

With regard to the design of conveyor chutes you can contact Mr. Larry Nordell via the web site here and the

Conveyor Equipment Manufacturing Association www.cema.org or the

Vibrating Screen Manufacturers Association www.vsma.org

Dear sir

1) What is the real significance of using fixed tripper in conveyor.

2) Can we replace this fixed tripper with flap gate . If not why? ■

1)A fixed tripper is essentially nothing but a mobile discharge point along an X or Y axis.

2) a flap/flip-flop gate simply allows the discharge of material to the opposite side. ■

Originally Posted by lzaharis

1)A fixed tripper is essentially nothing but a mobile discharge point along an X or Y axis.

2) a flap/flip-flop gate simply allows the discharge of material to the opposite side.

Dear sir

Please find teh attached file for coal handling, where in clinet has proposed to put FIXED TRIPPER on top of silo to feed on silo and onward conveyor.

Now my quiry is , can i replace the fixed tripper with simple flap gate . If not what is the functional reason .?

Attachments

flow diagram (PDF)

■

Originally Posted by guddu

Dear sir

Please find the attached file for coal handling, where in client has

proposed to put FIXED TRIPPER on top of silo to feed on silo and

onward conveyor.

Now my inquiry is, can i replace the fixed tripper with simple flap gate?

If not what is the functional reason?

Your clients suggestion wastes a lot of space,

effort and material and can be accomplished

in a much simpler fashion.

Are you weighing the oubound or inbound coal

using load cells in the silos?

I would sincerely suggest that you chat with

Mr. Lawrence Nordell and pay him for his time

about this as your system needs a lot of work

and is poorly laid out and it can be made much

more effective in cost per ton.

Ones engineering training work experience

are not something obtained for no cost. ■

Originally Posted by lzaharis

Your clients suggestion wastes a lot of space,

effort and material and can be accomplished

in a much simpler fashion.

Are you weighing the oubound or inbound coal

using load cells in the silos?

I would sincerely suggest that you chat with

Mr. Lawrence Nordell and pay him for his time

about this as your system needs a lot of work

and is poorly laid out and it can be made much

more effective in cost per ton.

Ones engineering training work experience

are not something obtained for no cost.

Dear Mr lzaharis

Iam trying hard to determine the coal stockpile height or coal stockpile critical height to limit the sponteneous combustion

I would like to be advised by you , what can be way to derive the same , if not is there any article to determine the critical height of coal stockpile?

thanks in anticipation ■

Originally Posted by guddu

Dear Mr lzaharis

Iam trying hard to determine the coal stockpile height or coal stockpile critical height to limit the sponteneous combustion

I would like to be advised by you , what can be way to derive the same , if not is there any article to determine the critical height of coal stockpile?

thanks in anticipation

Namaskar Guddu,

My sincere apologies for the tardiness in this reply

as I missed your last response.

The bad news is that you cannot prevent it and that you can

only control it after it has been observed.

Ideally if you have water supply in abundance you can wet the coal

with a heavy spray of water when stockpiling. This is dependent

entirely on the available water supply.

A coal stockpiles net height is more important in line with the

required capacity for the burners and the square area available for

the desired stockpile tonnage.

The only way you can prevent spontaneous combustion is with vigilence

and a good water supply for fire control and quenching of hot spots/smoke plumes.

Ideally you can create stockpiles that have concrete barriers to separate

X amounts of coal feed stock.

The only was to prevent spontaneouos is to prevent air from entering the

pile and thats something that cannot be prevented.

. ■

Dear friends,

In case of coking coal the stock height can be up to 16 mtrs or more,due to its non autoignition properties.

In case of thermal coal,due to autoignition, every one is trying to maintain a low height.But due to acute shortage of space.in many projec,

a height up to 15 mtrs are resorted to with adequate sprinkling and quick evacuation.

I have come across some plants, where the thermal coal stack height is 15mtrs.

Normally evacuation is by reclaiming.

Reclaiming efficiency is the best with trapezoidal stacks.Conical stack requires frequent reversals of reclaimer slewing .

The slew bearing life depends on the nos of cycles also.Hence,conical stack which requires frequent reversal of slew is better avoided.

With all these,conical stack may have to be resorted to due to stacking method/machinery used.

Rgds,

Nalinakshan. ■

On going through with my stocks I use the trapezoidal style which helps me on better calculating my stocks. ■