Combined Approach for Surface Mine Short Term Planning Optimization

7/29/2019 Combined Approach for Surface Mine Short Term Planning Optimization

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Chapter 49Combined Approach for Surface Mine . .

Short Term Planning Optimization. rZhang Youdi, Cai Qingxiang

Wu Lixin, Zhang Daxian

China University of Mining & Technology

ABSTRACT

A two-step approach has been developed for surfacemine short term planning by the authors. The first step ismid term control and planning by the use of GoalProgramming. This step gives optimal results for midterm planning (i. e. yearly or quarterly mine plan) aswell as a macro control for short term planning (i. e.monthly or weekly plan. )

The second step of the approach deals with short termproduction scheduling by the application of CADtechnique and Systems Simulation. An interactive colorcharacter graphic design system has been developed with asoftware package. The menu-driven and module-structured package provides sufficient functions forsurface mine short term planning and makes the modelvery flexible and user-friendly.

This model has been applied to a large surface coalmine for short term planning optimization. Satisfactoryresults have been obtained.

It is concluded that for complicated miningconditions this two-step combined approach gives anoptimal control of mid term planning, makes the shortterm planning easier to avoid blindness; it has beenproven that the Goal Programming is a powerful tool for

solving multi-objective decision-making problems; guidedby GP mid term planning, the CAD technique andsimulation software package for short term planning areable to be concentrated on their practicality andflexibility.

INTRODUCTION

The stratigic technical decision- making of a mineshould be taken in the stage of long term planning, whilethe task of short term planning (usually under a yearlybase of time period) is to arrange mining engineering torealize the objectives of long term planning, e. g. tosatisfy the requirement of mine production and orequality, to balance mining and stripping volimes, and toget the best economic results.

In the field of mine short terin planning,considerable work has been done on the application ofOperations Research and computers in the past twentyyears. Existing approaches for surface mine short termplanning optimization can be divided into three groups

A. Mathematical programming. For example,Linear Programming, Integer Programming, DynamicProgramming have been used (Davis, R. E. and


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500' 23rd APCOM PROCEEDINGSWilliarns,,C. E. , 1973 , Dagde len , K. and Johnson , T . The software package is totally menu- driven and'B.", 19 86 ) module-structured. These features provide sufficient

functions for surface mine short term planning work andB. Systems Simulation, including CAD technique make the model very flexible and user-friendly.

(Davey , R. K. , 1 9 7 9 )C. H ybrid approach. Most of them appeareh'in the

last decade. Syst enis simulation m ixed with LP approachcan be taken as an example (Fytas, K. and .Calder , P.

. . . .N. , 1 9 8 6 , ~ i l k e ' , ~ .. et al. , 1 9 8 4 ). How to handle the relation between mine long (mid)

term planning and short term planning to optimize the, ,' gross economic results is still a problem t o be well solved.

. .J,. .A NEWLY. DEVELO PED MODEL

. ,' r .

- ..A new -model has been 'developed f or short term

planning of a large surface coal mine. The re ar e two' mai n coal seams in t he flat- bedded coal deposit. Th e

sulfur co ntent and ash co ntent are quite different betweenthe two coal seams, yet . they are fluctuant in theirdistribution. Coal quality blending is the most importantproblem in this mine. In general, it is also a typical casefor, surfac e m ining. :

, .. T he moc!el.iss composed of 1 3 sub-m odels (mo dules ).. . ..The,general,stucture. . . .I of th e model,! sho wn in Fig. 1.

1 .A t y ~ s t e p pproach has been developed for surface

mine shot,t,Ferm planning optimization as follows.

- Step 1. Optimal control of coal seam productionallocation and scheduling. Goa l Programm ing is used torea l i se m~l t i~objec t ive ,ecision- making for coal qu ality. . . ,.and production optimization... 0 . . .. .

, . ." St;* 2.. Detail. arrang eme nt an d adjustment of m iningand stripping production scheduling. Thi s is realized byan interactive graphic design system and ,systemssimulation.

. . , .

COAL SEAM PRODUCTIONALLOCATION BY GP

In the past, single objective linear programming hasbeen used to solve this problem by predecessors. Th ere isonly one objective involved, the others are a set ofconstraints. Howev er, the main objectives which shouldbe taken into consideration in developing open pitproduction planning are: ore production rate and strippingratio, the demand of ore kinds and quality, location ofworking benches, productivity of mining equipment, orestorage and processing conditions, etc. In theseobjectives, some search for maximum value (e. g.prof i t) , some search for minimum value (e . g. cost ) ,and some search for "exactly equal" (e. g. ore gradecontrol ). ' These objectives a re o ften 'incompatible,incomparable, and graddd with each other. I such aproblem is solved as single objective decision, sometimesno solution is possible. Though the solution could beobtained, it might be far aw ay from the m ining practice.So we search for " the best" instead of "optimum:'solution which satisfies all the objectives and constraints.Here , goal programming is suitable. .

Because single objective decision system is the subsetof multiple objective decision system, the problems whichcan be solved by single objective linear programming canbe solved by goal programming. There are m anyproblems that can be solved by goal programming but notby single objective linear programming. Owing to thedeviation variables included, besides maximization andminimization, goal programming can realize approachingthe objective best, exceeding the objective best orlowering the objective best. This is unparalleled comparedwith single objective linear programming. The refore , t heapplication of goal programming is put forward toovercome the limitations of single objective linear,


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23rd'APCOM PROCEEDINGSprogramming. SC-expected value of sulphur content.

ashw-ash co nte nt of block (i , , ).Let xln to be th e decision variable of the block model. . - ASH-expected val ue of ash content.Am...AmI.-the up pe r lim it an d the low er lim it ofHere each va riable xi, is allowed to take values of on ly coal production in th e planning period.

0 and 1. 6 & , 6 deviation variable of coal productionabove or below A,,..

1 if block ( i , j k) is mined in a certain period 6&. 6- d ev ia tio n v ar ia bl e of co al p ro du ctio nXljt= ( 0 o therwise above or below A, . .6$ , 6 i- eviation variable of suplhur contentIn gene ral, the goal programming model is as follows:

, above or below the objective value.Achievement function : 6 6 deviation variable of ash conten t abovem i n a = {P I 611 + d & ), Pzd?, Pad:, P d d t, Psaf ) or below the expected objective value.Production objective:C t i j , Z i j , + dii - ?i = Am

' C ij zij, + 611 - & = A,Sulphur objective

Ye-plant yield.

The model described above can be modified accordingto the requirements in the practical application, such as:changing the sequence of priority, adding the constraintsof the productivity of mining equipment, requirement of. .Ash objective: ' ' washed coal, space for equipment operation, etc.

z i j , t i j , (~ah ;~ .- A S H ) +& - f = 0 1Mining reachability constraint: Take the surface coal mine quar ter ly planning as a

zij a < i -~j , case study.Mining minimum precedence constraint:. .. . Zij , < i.j.&. The v in e's designed annual production is 1 5 millionMining max imum precedence constrain t: tons of raw cpal. Shovels and trucks are used in mining

ZIJ,< I.J.P and stripping. Th ere are two principal coal seams.Mining bench smoothing constraint:

zip J < X Z , - . ~ , The commercial coal is classified into 3 categories:- Class A: .S P , > P ~ > P ~ > P ~

trB-coal to nn ag e of block (i , , k).S&-sulphur con tent of block (i , j , ).

Input the concerned parameters of quarterly (ormon thly) production planning and ru n the program. Th ecase study results are obtained as Table 1 and Figure 2 ,Figure 3. The results produced are satisfactory in termsof mining practice. Afte r blending, the coal qua litysaisfies the requirement.


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APPROACH FOR SURFACE MINE SHORT TERM PLANNING OPTIMIZATION 503

Table 1. Quarterly coal production and quallty control plan (3rd quarter, 1990)

. . .. . .

In Figure 2 and Figure 3 , the coal block is e x p r d by ' ", otherwise, it $ . ,xpressed by .'2". 'A","B",'C" represent the sequential monthly plan in this quarter.

Figurc 2. Thequality control scheduling map (coal scam No. I )A-1990.7 B-1990.8 C-1990.9 1

Figure 3. The quality control adndulingma p (coal scam No. 2)' A-1990.7 8--19 90.8 C-1990.9


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' 04 23rd APCOM PROCEEDINGSLetter and colour allocation

INTERACTIVE CHARACTER The so- called color character graphic mean s th atGRAPHIC DlCSI.CN SYSTEM. , . ,; . stripping benches are represented in letters , coal benches

. . .. in digits a n d d ifferent colors ar e assigned to differentBy the use of the software package the yearly plan, benches. All blocks ,on the same bench a re representedquarterly plan; onthly plan ;'even weekly 'plan can be with kame letters or digits,worked out. Th e operational procedure is as follows: ' .

1 . - ) ' .. . Initializing all benchesCreating geological data files. . ,-

, . . ~ . . . By the use of a plot-digit conversion program, all ofRunning specially designed programmes, all of the the benches will be digitized and the corresponding

benches in the' pit can be biocked in a given size (here 25 ' working files are set up ,. in which a set of .{W (i , j) ) a r eX 2 5 ( m ) ) a i d tk geological data fil& are established. " ' o bt ai ne d, w h e re W ( i , j ) E { 0 , 1 , 2 ) . If W(i, j ) ,=O thenSome prima ry elements are contained in ;hi ile& , s"ch:as bldck (i , ) is a mined block, W (i , ) = 1, n un-minedloess amount, rock amount? sulphur and a+ content of block and W (i , j) = 2 , an air block. A sartple is showneach block. in Figu re 4.

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Figu re 4 Curr ent statu s of a bench ', . . .

~ntk racti ve roduction scheduling. .

hivided ' k t 0 three windows (shown in f igure 5). Theexposed area of each bench will be displayed in window1; in window 2 the numerical results and in window 3

During the production scheduling, the. screen is the commands an d prompts. '


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APPROACH FOR SURFACE MINE SHORT TERM PLANNING OPTIMIZATION 505

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 S t a t u s : F 3GGGHHHHHJ44NN911111000000000000000001SSSS99999MMMMHHHGFFEEEEGGGHHHHHJ44NN9111110OOOOOOOOOOOOOOOOSSSSS99999MMMMHHHGFFEEEE upleft:5700 71000GGGHHHHHJ44NNR111111lllllOOOOOOOOOOOSSSSS99999JJMMHHHGFFEEEE1GGHHHHHJJ44NNRS1111lllllllllllOOOOOlSSSS999999JJJJHHHGFFEEEE coordt:6125 71550GGHJHHHJJL4NNR9S111SSSSSS11111111111SSSS999999JJJJHHHGFFEEEEHHJJJHHJJL4NNR99SSSSSSSSSSSSSSSSSSSSSSS9999999JJJHHHGFEEE 1--1240 (KBCM)JJJJHGHJJL4PNR9999999SSSSSSSSSSSSS999S99999999NNJJHHHGFFFFEE =================

ZHHHHJGHJJL4PQR999999999SSSSSSSS99999999999999PNNJJHHHGFFFFFEHHHHHGHJJL4PQR999999999SSSSSSSS99999999999999PNNJJHHHGGFFFEE BlockHHHHHGHHHK4PQR9999999999SSSS9999999999999999PPNNJJHHHGGGFFEE =================HHHHGHGHHK4PQR999999999999999999999999999999PPNNJJJHHGGGFFE locs : 0 .000

3HHHHFFGHHK4PQRRR9999999999999999999999999999PPNNJJJHHGGGFF rock: 0.438HHHFFFGHHK4PQRRRRRRRRR999999999999999999999PNNM4HHGGGGFE t o t 1: 0.438HHGFFFGHHK4PPQRRRRRRRR9999999999993999999999PPNNMMHHHGGGFFFEHHFFFFGHHK4PPQQQQRRRRRR9929QQQQQQ99QPQQQ9PPPPJJ~lMM4HHGGFFFFF Bench4GGFFF&GHBK4PPQQQQQQQQQQQQQQQQQQQQPPPPPPPPPP J J J JNHHGFFFFF================GFFFEEGHHK4PPQQQQQQQQQQQQQQQQQQQPPPPPPPPPP J J JNNNMMMHHGFFoes: 0 .000GF F F EEHHHK4 PQQQQQQQQQQQQQQQQQQQP P P P P P P P P P P J J J NNMHHGGFCFock: 35.563FFFEEEHHHK4PPPPPQQQQQQQQQQQQPPPPPPPPPPPNNNJJNNNMMHGGGFCC o t 1: 35.5635HFFFEEHHHK4PPPPPPPQQQQPPPPPPPPPNNNNNNNNNNNJJNMMMMM4HHGGGFFCC

Fl-Quit FZ-Save F3-Dig F4-Ref i l l F5-Areadig. F6-Arearefi l lF7-Conf irm 'F8-S croll F9-Elevation F10-CleancoalFigure 5 Screen design

In the GP model, it has been allocated that how man ycoal blocks on each bench should be mined out in order tomeet the coal production and quality requirements. Onthe given benches displayed in window 1, these blocks areautomatically mined out and displayed in their reverse-color. The production and quality of raw coal and cleancoal are displayed in the window 2. Now the , func t ionkeys shown in the window 3 can be used to adjust theresults from the GP Model. Th e cursor is alw aysglimmering and simulates the operating shovel. After thekey F3 being pressed, the blocks which the curser passeswill be mined one at a time. Th e calculated results aredisplayed in the window 2. After the key F5 beingpressed, by moving the cursor to form a closed area, thewhole blocks within it will be mined out. Th e key F4 an dF 6 play the opposite functions of the keys F 3 and F5.Th e reverse-colored blocks can be recovered one at a tim ewith F4, blocks within a closed area with F6 . Accordingto the highlighted areas with different letters and colors,the areas being mined on each bench and the relativeposition between bench fro nts are obviously shown. If th ekey F10 is pressed, stripping ratio and the indices of raw

coal and clean coal are displayed in th e window 2. On thebasis of the inform ation abov e, the planning engineer caneasily judge whether the engineering position of thebenches, coal production and coal quality have met therequirements of the mining plan. After the key F7 beingpressed, the next layer beneath the reverse-colored blocksbecomes visible. The n the results fro m the GP Model areadjusted and confirmed. An y part of the pit can bemoved into or out of the window 1 with the key F8.

Under the g uidance of th e GP results, the mining andstripping operations of th e other benches can .be finishedwith the same method described above. Th e operator candecide which or how many benches to be displayed eachtime. All of th e mining resu lts can be saved in. deff eren tfiles to plot the drawing and output the report of themining plan.

In brief, the technical feature of the interactivegraphic design system lies in :

1. Mining st atus a nd associated mining- stripping


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23rd APCOM PROCEEDINGS .

volume as well as coal quality indices can be clearlyf ;handled afterwards.represented on the screen at "real-time" along with the 'mining simulation process. 3. An interactive colour ,character graphic design

system has been developed as a strong tool for quick and2. Multiple "mining" and "recovering" procedures convenient production scheduling. Coloured mining plancan be selected by the function keys which makes the and associated mining-stripping volume as well as coal

mining simulation very convenient. I qtality indices can be distinc'ily represented on the screen. along with the mining simulation process. And multiple3. The structured "C" language is employed. "mining " and " ecovering" procedures can be selected

Controlled by which, multi-colour screen involving text ' with one touch of the function keys.. , .colour and reverse colow makes the mining plan distinctand intuitional. .. .. . . . .

, . . . .. '. . , REFERENCES'. . . . . .' . . . , ..4. A spc ial is developed to do the conversion , . .. . , . .

between ploi and digit, -by which exact mining volume . . . I . ~ a v i i ,R. E. and Williams, C. :E. 1973,. .associated with the front location can be obtained. , , . .. . . :. "Optimization procedwes'..for open pit minescheduling" , 1 th International symposium on

, , Computer Applications in the Mineral Industry,CONCLUDING REMARKS University of Arizona.

1. A'hybrid method has been developed for surface ; 2. Davey, R. K. , 1979, "Short Range Miiemine short term The optimization approach Planning", Computer Methods for the 80 's inincludes two steps: the Mineral Industry, Weiss, A. ; d. , SME/

. - . . . AIME, New York.he first step is the optimal cpntrol of coal seam

production allocation and scheduling by Goal 3. ~agdelen ,K. and Johnson, T. B. , 1986;Programming; ; "Optimum Open pit Mine Production Scheduling

. . by'. Lagrangian . Parameterization ", 19th-he second step is detail arrangement and adjustment - .APCOM Symposium, SME/AIME.of mining and stripping production.. schedulikg . by ' , ,

, .interactive grpahic design system and systems simulation. 4. , Fytas,. K. and Calder, P. N. , 1986, "AComputerized Model of Open Pit Short and Long

. 2. Goal programming can be effectively applied to. :. . Range Production Scheduling", 19th APCOMmine planning optimization. multiple objectives can .be ,Symposium, SME/AIME.comprehensively considered according to their ,differentpriority.. The constraints,, such as ,mining rkchabi lity , 5. Wilke, F. L. et al. , "Ultimate Pit andmining precedance , bench front smoothing, etc. are . .. , Production Scheduling Optimization ", -8thdirectly. included into the GP model instead. of being . , , . . APCOM Symposium, IMM, London, 1984.

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Combined Approach for Surface Mine Short Term Planning Optimization