Coal Miners • At this point you have rough quantification of your markets and your reserves • You are thinking room and pillar for #6 and longwall for #5 and #2 with mining seams one at a time from the top down. • You have an idea of your slope location and layout.
A Challenge • Problems with mining one seam at a time from the top down • You have no chance for blending of coal • Your least valuable seam (#7 is on top) and your most valuable (#2 is on the bottom) • The sequence may meet your mandate to maximize recovery • But your are putting the best coal for NPV maximization off for on the order of 30 to 35 years • It’s a disaster from an NPV maximization standpoint
An Alternative • Mining in one seam could lead the mining in the seam below by an amount exceeding the draw angle for subsidence from the seam below (Galatia did this for many years with the #6 and #5) • Your mining sequence would be much more constrained and take a lot more thought (ya – like Dr. Paul is going to care about the extra brain strain)
The #7 Coal Issue • #7 coal is lower BTU (around 10,000) but coal like this does and has sold in the Illinois basin • Further #7 coal has some of your best washability characteristics – especially for removing sulfur • You sell washed coal – not ROM most of the time • If that does not persuade you, your maximized recovery requirement will force you to mine in the #7 • Initial poor quality of a highly washable coal isn’t convincing anyone
Work out Panel Design Properties for Each coal seam • Determine whether #7 coal is minable by longwall or whether room and pillar will be needed. • For each seam Work out pillar and panel sizes • You indicated cutting of roof and floor • What areas will pillar size be controlled by floor strength • What areas will pillar size be controlled by coal strength • What kind of out of seam dilution will you have? • What machinery type and sizes (including cutting height) are you planning on going for
Once Your Draft Pillar and Panel Sizes are worked out • Run rock mechanics calculations to justify your design • You know how to size pillars by load • If you need pillar sizing by weak floor I do have a spreadsheet. • Will the roof hold up over the opening width • Use a design model that accounts for your high horizontal stresses and your decision to mine at an angle where you will have shear stresses in the roof. • What length and type of roof-bolt will you use? • Can have presentation on 2D papers Roof Rock Rating System • At this point of specifics are you finding any problems or mining constraints you did not believe you had last week? • (last week you basically said anything that is over 4 feet and not washed out or burned away by a dike is minable and that no seam interactions would render any further coal unminable)
After Getting an Idea of Dimensions and Extraction in Each Seam • How far ahead will mining in each seam have to lead the seam below? • Plan a sequence for what area you will mine first • Then look at how much you will be taking from each seam as you follow that sequence • There are places where you may have no minable #5 or #2 coal (washouts) yet you do have minable #6 and #7 • (This is draft work – not a finalized timing map) • Show a map of your general area by area sequence with the idea that once seam will lead the other – not all mined one at a time • How much coal from each seam will you have when you mine each area? • It will likely change from one area to the next since not all seams are equally minable or thick in all areas.
You Are Probably Now Looking at a Very Controlled Sequence • Your rate of advance in any seam is being controlled by the need to lag the seam above and stay ahead of the seam below. • You have geological constraints on mining in some seams • With these factors in mind how many panels or sections could you run in each seam? • Are you constrained by your market for coal or are you finding geometry and sequence restrictions are limiting your production more.
Jumping to Surface Issues • You know very nearly where your slope is • Pick the location of your offices, warehouses, washplants, roads, loadouts, rail loops etc. • Remember to consider your terrain and flooding findings from your earlier work • Look at your coal washability curves • What kind of wash plant do you want to have? • What size fractions will you have? • What equipment will you use on each size fraction? • What kind of coal refuse will you have? • (slurry to a pond, rock silos, belt press solids)
Thinking of the Refuse • Now you have an idea of the refuse types • Where will you put the refuse? • Estimate how much refuse tonnage those areas could handle • Show an initial map of your surface facilities location including waste locations.
Consider the Impact of Your Mining • Your mining is probably giving you some tentative tonnage ranges • What size plant are you likely to have, and now you know this does it change what type of plant you will have • Your underground miners are potentially going to cut roof and floor – when these volumes are added to the coal what tonnage do you have now? • What kinds of out of seam dilution will you have coming into your wash plant? • How are you going to reject this stuff? • Can you remove any of the out of seam dilution before it goes into your coal cleaning circuits?
Writing • Take your previous write-ups and correct the deficiencies found. • Write a section describing where your deposit is located, what is around it (making sure you point out how these things affect you or will serve you), what coal seams are in the area.
Metal Miners • Lots of MineSight work (ok its pretty much all your work for the next week – so everyone gets to do MineSight work) • Idris has now identified most likely scenario prices • He has also identified a high price scenario and a low cost • Eric has got transport and process finishing charges that you can use to back calculate your prices in concentrate • Probably need a processing correction • Copper smelter will charge about $120 per metric tonne of concentrate • To electrorefine the copper will cost about 13 cents a lb of copper. • 95% of copper in your concentrate will actually make it to market. • Determine the size of the ultimate pit under the high, low, and most likely case • This will probably require some changes in your cost parameters write-up as well.
Get a Handle on Your Push-Backs • You know your truck size and number of shovels. • If you keep 6 active bench areas what does that imply for the size of the push back? • Use this as the minimum size for pushbacks • Remember by involving only certain rows and columns in the block model in a push back you can control push back direction • You do not want to be pushing back in all directions at the same time – your trucks need roads to drive on.
Use 2D cross sections as well as 3D views to clearly show a feasible push back sequence. • (Drawings last week were impossible to see what was happening) • Clearly explain what direction you are pushing back and show how your push-back size effects only part of the pit at any time and is of size that accommodates you truck geometry and need for active benches. • Show that your phases cover similar amounts of time • Use tables or graphs to show the type and quantity of ore and waste being mined in any given phase • (You need to get this done this week because it is holding up you work with VALP, processing plant sizing, and Strategic Planner).
Provide Improved Views • Show your waste dumps and leach areas from multiple views so that more than a blue blob in plan view is seen.
Input your road network into MineSight • Obviously you will have some sort of road or route for your conveyor too. • For your roads provide the grade profile of the road • Provide your cut and fill volumes • Provide nice views that clearly show the road.
Still Missing • Underground ore reserve appraisal. • Do you have an underground reserve? • If so how big is it? • How did you decide if you have a reserve? • Provide views showing what you do or do not have. (I need to be able to tell what is going on in the view). • This is more MineSight work.
I don’t have your most recent write-up • I’ll try to provide feedback so you can update and improve it.