12 Quarry Operations ©2010 Dr. B. C. Paul Note – The slides contain many ideas about quarry design that are considered by the author to be common knowledge to those familiar with the subject. This material was not drawn from any one source in particular. The slides do contain many screen shots from the program MineSight which was developed by Mintec Inc.

The Impact of Deposit Shape  Consider Crushed Stone First  Some Deposits have a single thick layer of rock with significant overburden and fairly level. –These operations advance like strip mines –Backfill of pit depends on relative amount of overburden  Often may not fill back to original level like some coal strip mines –Truck and Front End Loader dominates –Quarries usually collapse the highwall in blasting so that equipment digs from broken rock pile rather than a face

The Dip Seam  Can have open pits similar to Phosphate or steep dipping seam coal  These kinds of deposits can also have lots of faults and complex geology –Local costs can be high –But $12-20/ton transportation cost is pretty significant for a $6 to $12/ton product. Break Even Limit To steep to backfill while Working – overburden is used To fill separate pits (or they mine Down the strike)

Midwestern Thick Seam  May get areas with very thin soil layers and then layer of layer of limestone and dolomite –Mines look somewhat like a true open pit Soil Layer

How Do You Decide Bench Height?  Safety –May be prescribed by a local ordinance –May come from a safe distance for no catch berm  Product Purity –Different layers may have different markets that require them to be separate  Less consideration on digging height because face is usually collapsed in blasting

How Do You Decide Bench Width?  Bench widths are usually very generous –Often have limited number of work areas  Most benches may be nothing more than catch –Grade uniformity issue for mill may not come up here  Slope issues are less critical –Toe to Crest slopes usually near vertical (high quality rock) –The amount of overburden compared to rock is often very small (doubling a to 1 stripping ratio is not much of an issue)

Pit Sequence  Grade control is usually mostly product control –You open up the rock layers you need for product  Because most rock is about the same grade the most profitable rock is the lowest cost –Lowest cost normally does work top down –May see very little of whole pit sides pushing back

Example of A Quarry Design Soil 10 ft A Aggregate Grade Limestone 30 ft. Waste Rock 5 ft. Chemical Grade Rock 25 ft Aglime and Aggregate Rock 80 ft. A Plan – Contract for soil removal Above pit Set up a 30 ft bench Use Dozers and Rippers on Waste Rock Set up a 25 ft bench chemical rock Try 2 40 ft benches on Aglime and Aggregate (Say the legal constraint is 80 ft Max bench height) I chose 40 ft to try to avoid different types of drills being needed For blasting operations.

Market Constraints  Aggregate 4 million tons/year  Chemical Stock 800,000 ton per year  Aglime 1,200,000 tons per year  Scrubbers 1,300,000 tons per year

Match My Layers and Markets Top is only good for aggregate – 4 Million tons 5 years 20 million tons (about 235,300,000 cubic feet or about 7,850,000 Square foot area) My Chemical and scrubber limestone here 2.1 million tons/year 5 years need 10.5 million tons (about 123,500,000 cubic feet or About 4,950,000 square foot area) Aglime 1.2 million tons 5 years need 6 million tons (about 70,600,000 cubic feet or about 1,770,000 square foot area if I only take top 40 ft bench)

Logic I Was Using  The Cheapest Material is at the top  Sell my best layer for my highest price products  I only mined aglime from the top of the 2 benches – I’ll go down further when I need to but the cheapest stuff is near the top  I got volumes knowing my rock was about 170 lbs/cubic foot and knowing thickness of the rock layer –Example – My 20,000,000 tons of aggregate  Multiply by 2,000 lbs per ton is 40,000,000,000 lbs  Divided by 170 lbs per cubic foot is 235,294,000 cubic feet  But the layer is 30 feet thick so 235,294,000 / 30 = 7,843,000 square ft.

My Property 5,280 ft 2,640 ft 1,320 ft 2,640 ft 6,600 ft. Access Road Consider Pit Area Here Processing and Stockpile Here

Pit Advance Strategy 5,280 ft 2,640 ft 1,320 ft 2,640 ft 6,600 ft. Access Road Processing and Stockpile Here Expand Pit This Way Then this A 10% ramp going Up 40 feet is 400 Feet long. (Make my pit 600 Feet wide) Coordinate origin

Geometry Trials 13,000 ft long 600 ft wide About 7,850,000 ft square My first guess is way to long for the property A fit about 4,700 feet long will have nice buffer space and fit better It would be about 1,680 ft which also fits

Lets Try Setting It Up in MineSight® I’m going to start a brand new file I call Quarry Demo – it has nothing in it At all

It Asks Me For Permission to Add the MineSight Starter Files Of course I say yes.

Now It Wants to Know About My Coordinate Area

I Set Up Coordinates That Match My Project When You Do Your Homework You will have a Greater thickness To deal with.

It Now Gives Me the Initial MineSight View

I’m Going to Put In My Property Boundary You can see I Have created an Active edit Object named Property

I’ll Also Create Gridset That Shows Land Sections My gridset has Squares every 1320 feet (which happens To match the Dimensions for A quarter section Of land)

Gridsets and Edit Grids  Gridsets are usually multiple planes used for visual control –I used them to rapidly move through cross-sections and levels on by mine when I was doing pit expansion and sequencing  An Edit Grid is a single plane that is used to aide drawing things –When you are entering things in 3D stuff may really not go where it looks like it is from one view point –Edit grids let you fix the plane you work on and snap to intesections and corners of the grid (which is what I want to do now)

Create An Edit Grid I attach my Gridset to the Viewer and set The display to The zero plane (property lines Are done on the Zero datum Plane in surveying)

I’m Going to Make an Edit Grid from the 0 Datum Plane of My Gridset I pick the Select Edit Grid Icon Then I left click On my pretty Green gridset Then I click the Gray box to Attach just my Edit grid to the Viewer.

I Do A Little ReArranging Edit Grids are Gray (by default) And Gridsets are Green. I changed the Background so You could see the Gray edit grid. I also turned off My gridset.

I’ll Set The Viewer to Snap to a Point (So if I get close to a quarter section it will snap there)

Next I’ll Tell My Computer I Want to Draw a Polyline (for my boundary of course)

I Click My Way Around the Property Boundary When I’m done I Right click my Mouse.

My Line Turns Red (Indicating that MineSight® believes I’ve completed a Polyline) I now click on MineSights® Unusual save Icon.

The Line Turns Blue and My Property Boundary is Saved I click the yellow Open box to Close my edit Object.

Now I’m Going to Set-Up to Draw My Quarry I set up a gridset That was every 100 ft. I attached it to the Viewer and set it To the 150 plane (my surface Elevation for my Project – but not Yours) I created a Quarry Contours object And put it in edit Mode.

What I’m Going to Do  I’m going to draw my quarry with the pit expansion tool –I’m going to start from the top and work down  Why would I do that –Because I’m going to put in my roads this time –Often I really want my road to come out a particular point –I can control where my road starts or end from where I start my pit

Fire Up the Pit Expansion Tool

I’m Going to Set Up to Digitize My Base String on the 150 level and go for a single expansion

I Digitize My Base String Note that I am going To expand down for My first bench only.

I Set to Expand Down and Inward Note that I am Using a much more Narrow berm (bench) area than Is practical for a Quarry. (There is Currently a bug In the expansion Tool that is only Likely to be Triggered in a Quarry setting)

This Time I Will Include My Haul Road so I go to the Road Tab When I click Add It will add by first Road. The default name Is road one but I can change the Name according to My choosing Note that the status Is Unset. I click on Edit to Provide info on my Road.

The Edit Road Box Opens Check that it is Going to begin The road on the Right level

Identify the Road Start Point Click on the point Icon And then click on The spot you Want the road to Begin The pretty green Dot appears.

Specify Road Width, Grade and Direction. The road grade is Given in Decimal form. Thus a 10% grade Is entered as is clockwise 0 is counter- clockwise

When You Exit the Edit Box Your Road Now is Listed as Set

Click Preview to Have a Look at Things You of course Click apply once You are happy.

I Exited the Pit Expansion Tool Without Triangulating Because I Had Some Issues to Deal With

Current Pit Expansion Problems  Quarries often have very wide benches or berms –Quarries usually have fewer working benches and often collapse the face in blasting so more work room is needed on the bench  When the bench gets wide enough to block the road with just one level down the software won’t draw in the road –(The problem is being fixed) –This issue will not appear in most open pit mines but can appear in quarries with very wide benches  The road start point needs to be near a point on the base- string –Almost all pits have enough base string points that this is not an issue –A quarry with a very simple shape and corner points defining the base string might not have a point on the base string to start the road if you start in the middle  There is a fix that I will show you.

Pondering What I Will Do Next I have a 8,000,000 square Foot top bench pit. I need 5,000,000 square Feet for my chemical Grade limestone. I also need to strip off About 5 feet of reject stone. I’ll get my chemical grade Stone close to my Process point first and Probably strip off most of The reject rock.

I’m Going to Widen My Bench to 300 feet I will do this with A Polyline Offset. I must first select The polyline to Offset I pick selection Make new Selection.

I Click on the Crest of My Next Bench and Right Click to Complete Selection Note that my Selection has turned Red.

I Then Select Polyline Offset

The Offset Polyline Box Comes Up But Most Everything is Gray MineSight Sometimes requires You to select twice (this allows you to Select a bunch of Things for an Operation but then Allows to apply that Operation differently To different parts – Not handy to us Now but it can be Work saving) Click on reselect And then reselect The same Polyline.

Click on the Line and Then Right Click Note the yellow Overcolor that Allows you to Identify the Specific part of Your selection you Will work with this Second.

The Menu Is Now Alive I will specify a 270 foot offset (30+270= 300 foot wide working Bench) I’ll also preview my art work.

It Shows Me The Offset in Each Direction It gives me Check-offs to Determine which Offset to keep. I will keep the Second to the Inside.

Fill In My Window and Click Apply

My Work Finishes and My Box Goes Gray Note that if I had A bunch of lines To offset I am now Ready to reselect Without having to Evoke the offset Command a Separate time (not valuable to me Right now but could Be in other Circumstances).

I Close the Box and Query the Offset Line I note that I have Not removed Enough shale to Get to 5,000,000 Square feet to take For chemical stone. This means I’m Going to have to Move some points On the offset line to Uncover enough Chemical grade Stone.

I Right Click and Save to Get Ready for My Next Move

I Select My Offset Polyline My game plan is To move the line Back and shrink the Bench to just wide Enough for truck Traffic in areas Where I will no Longer be Expanding the Quarry. (Remember this Line defines the Area where I will Have removed the Reject shale to Uncover the Chemical grade Limestone)

Go to Point Move (To move points on my polyline)

I Shift My Points Note I am leaving Generous room For haul trucks to Move – but not to Be collapsing faces During blasting.

Right Click and Save My Work

I Query My Line Again This time I have Enough chemical Grade rock Uncovered but Having room for Be to rip and Load the shale Into trucks is Pretty shaky.

I Make a Few More Adjustments and Prepare for another Pit Expansion Note I have now Left full width working Benches only to the South in the direction Of future pit Expansion.

Fire Up the Pit Expansion Tool

I Get A Warning It tells me I have Been fooling around Outside the pit Expansion tool and Asks me for Permission to Delete the work and Go back to the Pit expansion My answer is heck No.

I Set Up My New Base String Level set on 120 Pick copy Click Add Click my new Base string.

I’ve Got the New Base String

Set to Bench Down 5 feet through the Reject Shale

Set Myself Another Road

Pick My Road Starting Point and Parameters

Finish My Next Bench Down

Use Point Moves to Set My Bench Width for Stripping Shale

Make A 25 Foot Pit Expansion Down into My Chemical Grade Limestone Note that I made A road Switch back going Counter-clockwise

Do A Few More Point Moves to Get Me a Good Working Bench

My Thinking  I need 1,800,000 square feet of aggregate grade limestone if I use just 1 40 foot bench  I also have a bunch of shale waste and very little space to put it. –I’m thinking of dumping it in the bottom of my pit  In order to not cover reserves I will need to go down at least 2 forty foot benches to dig a hole for my waste.  I’m going to check out some measurements for what I will try next.

I See I Have 3,400,000 square feet uncovered and only need 1,800,000 Yes I’m playing With the Query Tool again.

I’ll Check How Much Area I Have Stripped the Shale Off Of

Then I’ll Check the Length of My Pit I put my curser On one point and Holding the left Mouse button Down I drag it Across my Distance The reading below Shows me my Distance.

What I’m Planning I’ll dump my shale In the pit along this Backside.

Figuring the Room Needed for My Waste Shale  5,300,000*5=26,500,000 cubic feet of reject rock –26,500,000 / 3600 = X X 7361 = 0.58X^2 X= 113 Height of pile 65 feet

Figuring My Rock Removal Area for Aglime  I need about 1,800,000 square feet for one bench and 900,000 for two The problem is my aglime Area if I expand down now is 3,400,000 – way too much I’ll experiment with my string I’ll expand down for the next Bench.

First Adjustment Try I got it down to 1,600,000 square Feet If I get 2/3 rds from Top 40 feet and 1/3 rd from bottom Top would be 1,200,000 square feet Bottom would be 600,000 square feet

Try Two I still have 1,500,000 on The top bench

I Think I Have the Take Out Area for the Top Aglime Bench 1,200,000 square Feet achieved Now for a pit Expansion down.

Set My Level and Select My Base String

Expand Down Now I Need about 600,000 area for The second bench Down.

Adjust the Area to 600,000 Square Feet for the Expansion Down

Expand Down for the Last Bench

Triangulate the Surface

Our Quarry Our 30 foot Aggregate Bench The 5 foot shale Stripping area The 25 foot Chemical grade Rock Two 40 foot Aglime Benches

Our Aglime Benches Advance This Way

Our Aggregate and Chemical Grade Benches Advance South

Our Haul Roads Route goes clockwise down 30 feet to the base Of the Aggregate Bench Then down 5 feet for shale stripping Then turns Counterclockwise down the chemical bench

Rest of Our Haulage Route

The Role of Our Quarry in Future Work  Our Next Unit will be on Production Blast Design –We will use our Quarry to provide the benches we will be designing blasts for  Our Last Unit will be on selection of trucks and loaders –The haul roads and production targets from the quarry we designed will be the mine we will pick our truck and loader fleet for

Oh But You Don’t Have A Quarry to Work With  That’s why I’m going to give you Assignment 10 which will provide you the opportunity to lay out your quarry –Just as my quarry was a 5 year plan and showed where I would get the rock for the first 5 years –Yours will be a 5 year plan also!!!

And As An Added Bonus!  We Get to Plan Out the Time for Our First Exam – Woopy!!!