Senior Design – Week 3

2014 Projects

A General Comment

• Team leaders need to get me team member assignments.

Coal

• Market Adjustments– Hutsonville is $34/ton – not $46/47– Orient Market gets you $38/ton because your shipping

cost was $7/ton over the $6/limit– If you took the boiler market you get $46/ton – not $50

since you went $4 over on transportation– Your price analysis indicated $46/ton unless the coal

exceeded 0.2 lbs SO2/MBTU (all coal will exceed some) sulfur where you started to impose a penalty• Any coal costing more than $6/ton to ship needs to have the

excess above $6/ton taken off of the coal price

Dealing with the #7

• Your company attorney has informed you that discarding the #7 coal on grounds of poor quality is a contract violation – your plan to pass over the #7 is rejected.

• Quality realities– Steam coal is bought by the BTU– Assume your $46/ton base price is for 11,000 BTU per

pound• Adjust you coal prices up or down linearly for either exceeding or

falling short of the 11,000 BTU/lb– (Note you will actually sell washed coal in most cases)

Make a First Draft on Minable Coal Regions

• For each coal seam– Trace around areas where your coal is 4 feet or

more thick (unless you decide to mining thinner coal)

– Cut out regions where you believe washouts or dikes prohibit mining

– Make Version A minable coal area maps for each seam

Look at Innerburden• When one seam comes within about 50 ft of another you are in ultra-

close range– Mine support structures and entries need to be lined up

• What areas of your each coal seam have minable coal in a neighboring seam within 50 ft?

– If you get within 20 ft of another seam look at the innerburden composition• If it is mostly shale or clays – It could fall through between seams• If it is mostly massive sandstone or limestone – strong stuff – you might get within

10 ft.– Create a version B coal map where you identify any “minable” area from

map A that might fall through between seams• Obviously at least one of the seams will be excluded from mining in this area

– On your version B coal mine maps indicate any “minable” area where coal where structure line up will be mandatory

Look at Seams impacting Each Other

• If the lower seam is mined first rock up to 10 times the thickness of the lower seam could fracture– This is unlikely to be a problem until closeness is less than 6

times the thickness of the seam below.– Example – coal seam #5 is 40 ft above coal seam #2 where coal

seam #2 is 6 ft thick and is mined first• 6 X 6 is 36 ft – coal #5 if within 36 feet of coal #2 will experience

increased mining costs and safety issues• Since #5 is 40 ft away from #2 at this point it is a non-issue

• Create a version C map of each seams minable areas showing any place the innerburden is less than 6 time the thickness of a minable area of the seam below.

More Mutual Impacts

• If the seam above were mined first remnant structures could force stress bulbs down into the rock around the seam below.– Large barrier pillars tend to spread stress out and

not “punch” too far down– Vary small pillar slivers tend to crush out and not

project stress– Inbetween sized remnant structures could punch

through

Remnant Structure Range• Haycocks Equation

– 110ft - .42*% massive sandstone or limestone• What is a remnant structure

– Look for a pillar with a maximum dimension of• 5*sqaure root (overburden thickness)

• For on your map C identify areas of each seam that are still on your “minable list” that are within remnant structure range of the coal seam above.– Example coal seam #5 is located 60 ft below coal seam #6.

• Innerburden is about 80% massive– 110 – 0.42*80 = 76 ft– Remnants could project stress down 76%

• If I left remnants in my #6 workings and #6 was mined first it could cause trouble in coal seam #5

Look At Your Coal Seams• What is your minable area of each coal seam if you mine top down?

– What tonnage do you have?• What is the minable area of each coal seam if you mine bottom up?

– What tonnage do you have?• (Note top down or bottom up does not mean that one seam is

completely mined out before another starts. One seam leading the other meets the requirement).

• You indicated market constraints of about 15 million steam tons and 3.7 metallurgical tons per year.– In general a mine with less than about 20 years reserves is economically

sub-optimal because you are spending excessive capital making it too big– Do your reserves have any implications for your mine-life if you are getting

about 50% recovery? Are you most likely resource or market constrained?

Look At Your Mine Roof In Minable Areas

• This will probably require more thickness isopacks.

• For each seam look at the thickness of the immediate roof– Is there a trend in either thickness or type of rock?– If there is make maps showing thickness of your

roof rock– If the roof is about the same mapping trends and

dividing into areas is unnecessary

Look at Your Coal Floor

• Is there any trend in the thickness or type of floor you have?– If yes you probably need a floor thickness isopack– If not a general condition might be enough.

Consider Your Mining Method• Your maximum recovery mandate pretty much requires

you to consider longwall first (unless pillar retreate or just room and pillar give an immediately higher recovery)– For each coal seam

• Is there anything in the immediate roof that makes longwall either favored or not favored?

• Is there anything in the floor that makes longwall either favored or non favored?

• Longwalls may require breaking of more than just a cosmetic immediate roof – is there anything in the first 10 feet above any coal seam that bodes badly for longwalling?

• Are there any other areas that might be exceptionally difficult or unsafe to mine because of roof or floor conditions?

Propose a Mining Method for Each Coal Seam

• Look at your minable coal regions and features that break the continuity of mining– Identify the areas where you might run mains, or put in

shafts of declines.• What are the principle stress fields in the area?– How strong is the horizontal compared to the vertical stress?– How do you want to orient your mining direction relative to

the stress?– Do you have a favored direction of advance due to drainage

maps (you did them last week)?

Do a Sketch of the Mine Advance

• Sketch in where you will enter the mine– Indicate whether you are thinking decline or shaft

• Sketch in your mains (just a line diagram is good enough for now)

• Sketch in panel orientation and direction of mine advance

• Indicate your target mining rate.• Indicate anything special that you may be doing in

cutting roof or floor.

Writing

• Coal write-up was generally quite impressive• Nice color charts for innerburden thickness

– Was some lack of uniformity in heading.• Make a few clean-up revisions• Write a report on the extent of coal reserves in the area

– Prepare maps with suitable headings and tables showing things like thickness, exclusion areas, roof or floor conditions

– Your report should discuss how you obtained information or drew conclusions about minable and unminable areas

Metal Miners

• Your Price Histories are not inflation adjusted 2014 dollars– The rational connection between price forecasts

and market histories or predictions is not apparent to me. You need to get this right.

• Water– You have much more basis– Assume water is $2/1,000 gallons for rights plus

the cost of your wells, pumping, and any treatment

Tune Up Your Open Pit• You appear to have a mining cost• You appear to have an ore type and recovery

– Oxide is only unique one– Not sure you have decided on a low grade process– Then waste

• You have your transportation charges– Get your smelting charges (hint Western Mine Cost Service has

information on smelter charges)• Need to Get Slope• Check ultimate pit at Max, Expected, Min valuations with slope

constraints• Look to see if you have likely underground targets

Draw Out Your Truck and Loader Geometry

• Show what is on a bench in terms of turning and moving equipment

• What is your likely push-back width?• Try to develop an optimal series of stage pits– Pay particular attention to whether processing of

oxides will be life of mine or only early– Pay attention to when sulfide processing starts

More MineSight Drawing• With your estimated waste dump size

– Draw in your waste dump• If you have similar leaching facilities draw them in as end of mine

features• Draw in your tailings pond• For all these facilities check to make sure the size of the pond, pad,

or tailings pond is equal the the amount of material it will ultimately contain.

• Select your facilities location– Draw in your roads

• These roads should be controlled for slope• These roads should show the cut and fill to build them• (If you need training on doing this ask)

Writing• Write an Appendix on how you got the figures for your cost

matrix for running MSOPT– As an Example suppose

• Copper sells for $3.30/lb but you produce concentrates• $3.30/lb copper has to be electrolytically refined

– Suppose this cost 10 cents per pound (these numbers have not been checked and should not be used directly)

– Copper concentrates have to be smelted – suppose the charge is 40 cents per pound of copper in concentrate

– The concentrates have to be shipped to the smelter – suppose the cost per pound of copper in concentrates is 30 cents

– Copper in concentrate would then be worth $2.50/lb

– Your recoveries and processing costs you have already estimated

The Appendix

• Your appendix should show the numbers you used in your MSOPT Economics page– It should explain – with sources included – exactly

how you got each number– If relevant you should show how you calculated

each number

A Specific Heading Area in the Appendix

• You got your mining cost/ton• You did fleet calculations to get the loading and

haulage cost– Show that your selected loader and truck are a

match for each other– Show whether your truck is weight or volume limited– Show how many passes the loader must make to fill

the truck• Address what fill factor you used for the dipper or bucket

More on Haulage Appendix Area

• Show how you got your hourly operating costs and ownership costs

• Show the availability you used• Explain your road approximation• Show that the number of loaders you have is a

match to the number of trucks– Show typical truck cycle times and loader cycle times– Show your FPC truck and loader match page to

establish that there is not a significant wait time

Appendix Continued

• Show how you ultimately got a cost per ton for trucking and loading– Show how you selected the fleet mix you would

use• You will need similar work for your blasting

cost only it will be much more general and similar to what you presented in class

Comment on the Appendix

• Because this appendix cuts across several of your peoples work it will probably have more than 1 author

• It will likely be quite long• It is an appendix because it is necessary to

know how you got all the numbers you used for MSOPT, but it would probably distract from your ultimate pit size and planning to make these details part of the main text.