ODM a New Approach for Open Pit Mine Blasting Evaluation (Dr. Taji)

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published online 18 July 2012Journal of Vibration and ControlM Taji, M Ataei, K Goshtasbi and M Osanloo

ODM: a new approach for open pit mine blasting evaluation

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Article

ODM: a new approach for open pit mineblasting evaluation

M Taji1, M Ataei2, K Goshtasbi3 and M Osanloo4

Abstract

In open pit mines, the blasting operation should be effectively optimized at the lowest possible total cost, providing

technical specifications and the required safety norms. The optimization demand measurement (ODM) value of blast

should be evaluated by considering blast results and other mine unit operations, comprehensively. The present research

proceeds by taking into consideration seven blast results including degree of fragmentation, muckpile, overbreak, boul-

ders, bench floor and toe conditions, environmental considerations and misfires. Consequently, these results have been

rated and classified. In the ODM, a value could be assigned to each blast, with lower values corresponding to better

results of the blasting operation. The ODM procedure indicates a relationship between blasting results, drilling and

loading performances. The specific mine unit operations index and the blast block situation rating are introduced in

order to determine the ODM value. The blast results evaluation and its effects on the mining operation are analyzed by

utilizing the blast results matrix [z], the performance matrix [P] and the ODM matrix [O]. Based on the results as well as

considering optimization, blasts are classified into five modes: very good, good, relatively weak, weak and very weak.

Thereafter, the ODM procedure is applied to the blasting operation at an Iranian iron ore open pit mine (Chador Malu),

with nine blast blocks. In summary, this approach could help design engineers to recognize the optimization demand of

the blasting operation at different mining conditions.

Keywords

Optimization demand measurement (ODM), open pit mine blasting operation, blast block situation rating (BBSR), blast

results matrix, performance index

Received: 7 February 2010; accepted: 9 May 2010

1. Introduction

To optimize blasts, the analysis of blasting results isnecessary in an open pit mine. The data interpretationmight cause successive modifications of the design par-ameters of a mine operation (Lilly, 2007). To achieve aneffective optimal open pit mine blasting operation aswell as its global evaluation, the main blast resultshave to be analyzed. The process could lead researchersto three important questions. First, what are the pre-sent blasting operation conditions? Second, what pos-ition should be given to the present blasting operation?Third, which design will yield better results?

Since 1966, many researchers have studied the evalu-ation of blasting operation results. In Table 1 the mostfamous and important studies that have been presenteduntil now have been reviewed. The table shows manyindexes for evaluating blast operation. Some of them

such as the degree of fragmentation (DF) and specificcharge (Sc) have been widely used in evaluation.However, some less-common indexes such as the digg-ability of loading machines (DL), explosive cost (EC)and energy consumption (En.Cs), have also beensuggested. These indexes are not independent param-eters but are based on some the parameters such asbench floor conditions and boulder characteristics.

1Science and Research Branch, Islamic Azad University (IAU), Tehran, Iran2Faculty of Mining, Petroleum and Geophysics, Shahrood University of

Technology, Iran3Tarbiat Modares University, Faculty of Engineering, Tehran, Iran4Amirkabir University, Faculty of Mining, Petroleum and Geophysics,

Tehran, Iran

Corresponding author:

M Taji, Science and Research Branch, Islamic Azad University (IAU),

Tehran, Iran

Email: [email protected]

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Some indexes such as loading equipment productivity(LP), specific drilling (Sd), environmental considerations(E.Co) and secondary blasting (SB) are important but inprevious studies have not been studied comprehensively.

In order to develop a rational and economical opti-mization of blasting operations, the present study hassuggested a new approach to measure the blast results.In brief, the proposed optimization demand measure-ment (ODM) is a quantitative procedure used to assessthe degree of optimization demand for open pit mineblasting operation.

2. ODM procedure

The ODM is based on a systematic approach and inte-grates knowledge from theoretical analysis, experiencesand monitoring, so can be utilized to compute and deter-mine the ODM values for different blast block situation(BBSs). The BBS is determined and classified based on theblasthole water ratio, the number and type of free face, theratio of length to width of the blast block and type of blastblock material. The blast block situation rating (BBSR)considers blast working conditions to rationally compareblast blocks. So, it could be enter blast operation special

Table 1. The most famous and important studies regarding the evaluation of blast operation

Reference EC OC El.Cs En.Cs TC Sc Sd DL Pe LP Cr.P MT Mu DF E.Co SB Di

Hammes (1966) # #

Mackenzie (1965) # # # #

Da Gama (1990) # # # # #

Nielsen and Kristiansen (1996),

Nielsen and Lownds (1997)

# # # # #

Williamson et al. (1983) # # # #

Hodjigeorgiou and Scoble (1988) # # # #

Taqieddin (1989) # # # # #

Hunter et al. (1990) # #

Stagg et al. (1992) # #

Eloranta (1993, 1995, 1997) # # # # #

Da Gama and Lopez Jimeno (1993) # # #

Fuerstenau et al. (1995) # # # # # #

Mckee et al. (1995) # # #

Cunningham (2005) #

Adler et al. (1996a, 1996b) # # # #

Moody et al. (1996) # #

Frimpong et al. (1996) # # #

Eloranta (2001a, 2001b, 2007) # # # # # # #

Kanchibotla et al. (1998, 1999) # # # # # # #

Workman (2000,2001) # # # #

Harris et al. (2001) # # #

Grundstrom et al. (2001) # # # #

Singh and Yalcin (2002) # #

Workman and Eloranta (2008) # # # # #

Singh et al. (2003) # # #

Hamdi and du Mouza (2005) # #

Mosher (2005) # #

Kojovic (2005) # #

Morin and Ficarazzo (2006) # # #

Singh and Narendrula (2006) # # # #

Ryu et al. (2006) # # # #

Bremer et al. (2007) # # # #

AOG (2007, 2009) # # # # #

Calder and Workman (2008,2009) # # # # # #

EC: explosive cost, OC: operational (blasting, drilling or loading) cost, El.Cs: electrical consumption, En.Cs: energy consumption, TC: total costs of

mining, Sc: specific charge, Sd: specific drilling, DL: diggability of loading machines, Pe: expert personnel LP: loading equipment productivity, Cr.P:

crusher productivity and delays at the crusher, MT: mill throughput, Mu: condition of muckpile, DF: degree of fragmentation and required size

distribution of fragmented rocks, E.Co: environmental considerations, SB: secondary blasting, Di: dilution constrains.

2 Journal of Vibration and Control 0(0)




characteristics such as: (1) the solutions to overcome theblasthole water problems, (2) initiation and priming sys-tems by considering the effect of blast block size and shapeand the number of free face, (3) the necessity of blendingprograms or fragmentation degree limitations by consider-ing the effect of blast block material type (ore, waste, oreand waste). To develop the ODM, the blast blocks needsto be divided into five classes or representative blast blocksbased on BBSR. S1 shows water presence or the blastholewater ratio and S2 indicates the number of free face/pres-ence of the buffer of broken rock, resting on one of the freefaces from the previous blast. So, S3 and S4 indicate theratio of length to width of the blast block and type of blastblock material, respectively. Every blast block posited inthe BBSR class is numbered by 1, 2, . . . , j, . . . ,m, respect-ively. In principle, the BBSR helps to optimize blastdemand assessment according to very similar blast work-ing conditions.

To apply the ODM in open pit mines, the followingpoints are emphasized.

1. In an open pit mine, the properties of blast are likely tobe different from one to other blocks. In other words,the blast results will be different for each block. Hence,the optimization and ODM values for different blastblocks will be different. To develop the ODM, firstdetermine the BBSR class of the blast block.

2. When the blast results are determined and rated,their contributions to the ODM values are expressedby a dimensionless numerical value (Saaty, 1980;Wang et al., 2005) based on the general principlesand experiences from the open pit mine blasting spe-cialists, equipment operators and mining engineers.

3. A m � 1 matrix [z] can be compiled by using theblast results and their assigned values.

4. In fact, the weight and importance of each blastresult is different. To determine the weight andimportance of each blast result, we should developa performance index.

5. By transforming the specific mine unit operationsindex (Suo) measured in each blast block into theform of the specific mine unit operation ratios, a1�m matrix, i.e. the specific mine unit operationratio or performance matrix [P] can be obtained.

6. By multiplying [z] and [P], a m�m matrix [O] isachieved. The elements Ojj along the leading diag-onal of the matrix [O] are the ODM values for the jthblast block. Figure 1 demonstrates a flowchart of theODM procedure.

2.1. Blast results

As mentioned previously, the seven main blast resultsare based on theoretical analyses as well as engineering

practice to discuss empirical assignments These are thefragmentation degree, the muckpile, the overbreak,bench floor and toe conditions, boulders, environ-mental considerations of the blasting operation andcondition of misfires (Jimeno et al., 1995; Katsabaniset al., 2005). The seven blast results are divided intoclasses with numerical values of 1 to 20. A blast resulthigher assignment value indicates a low optimal and ahigher degree of optimization demand in the blockblasting.

2.1.1. The degree of fragmentation (�FR). The fragmenta-tion degree is one of the most important factors ofblasting operation outputs. Apart from the classifica-tion of size distribution or screening of the muckpile intreatment plants, there is no method which enables aquantitative evaluation of fragmentation in conditionsthat would be trustworthy. The fragmentation degree(zFR) is divided into six classes. According to Table 2,these numbers show the numerical assigned value ofoptimization demand for the blast block in an openpit mine blasting operation.

BBSRj

Blast results matrix [ζ]

ζFL ζBOζOVζMUζFR ζEN ζMI

Classification of (ζj)

Specific mine unit operation index

Performance matrix [P]

ODM matrix [O]

ODM values

Calculation of specific charge, specific drilling and specific loading of every blast block

Relative evaluation of blast operation:

Figure 1. Flowchart of the ODM procedure.

Taji et al. 3




2.1.2. Condition of the muckpile (�MU). Table 3 shows thatthe optimum geometry, height (Hm) and displacementof the muckpile depends on the applied digging andloading system.

2.1.3. The overbreak condition (�OV). A typical overbreakcondition and remaining rock after blasting is given inFigure 2. It shows damage and problems in the diggingand loading system as well as around the blast block

Table 2. The degree of fragmentation (zFR)

Class I II III IV V VI

Fragmentation

efficiency (%)

>95 85–95 75–85 65–75 50–65 <50

Qualitative Excellent Very good Good Moderate Unsuitable Very poor

zFR 1 4 8 12 16 20

Table 3. Condition of the muckpile (zMU)

Class Description

zMU

a b

I � Need to clean up more area 1 7

� The productivity is low (shovel)

� Loading safety is good

� Loading operation is easy

II � Irregular profile 4 12

� Need to clean up more area

� The productivity is low (shovel)


III � Moderate clean up area 7 1

� The productivity is good (shovel)


IV � High necessity of clean up * 10 16

� Need to clean up more area

� The productivity is very low (shovel) ** 12 20

� Loading safety is very good

V � Low clean up area 16 4

� The productivity is excellent (shovel)

� Loading safety is dangerous (loader)

VI � Muckpile displacement is very low 20 10

� Shovel operation to face wall clean up is difficult

aUsing loading equipment with access height lower than bench height (maximum access height is 2/3 bench height).bUsing loading equipment with access height comparable to bench height.*Suitable bench width.**Low bench width.





drilling operation. Table 4 indicates the assignedoptimization demand value of the overbreak (zOV).

2.1.4. The bench floor and toe condition (�FL). Figure 3shows a typical bench floor and toe remaining rock,where ‘HF’ is the average increased height of benchfloor and ‘J’ is subdrilling. The optimization demandnumerical values of the bench floor and toe conditionare evaluated from Table 5.

2.1.5. Boulders and oversize characteristics in the muckpile

(�BO). Important factors in boulder evaluation in themuckpile are: the amount of boulders in the muckpileas a volume percentage (MBO%), loading operationsafety degree, effect on productivity and loading equip-ment delay as shovel loading rate, secondary breakagemethods, the necessity of secondary blasting, positionof boulders in the muckpile (as shown in Figure 4),boulders size and probability of secondary breakagein the next blast blocks, delay at the crusher and theloading equipment and flexibility of breakage methodto extraction. The classification of boulders and over-size conditions (zBO), are given in Table 6.

2.1.6. Environmental considerations (�EN). The environ-mental considerations for blasting consist of airblast,ground vibration, noise, flying rock, dust and fumes.These often causes environmental and productionproblems such as decreasing productivity and increas-ing equipment damage, increasing risk of loss, buildingdamages, labor and operator injures and finally increas-ing mining costs. Some of the factors should be con-sidered for evaluating of environmental considerationsof blasting operation include: (1) the presence of officebuildings, mine shops, warehouses and their distancefrom the pit; (2) the position and location of the dor-mitory, urban areas; (3) the distance between the mainroads, haul roads, service roads, in-pit roads to theblasting site; (4) the position and location of the radio

Tab

le4.

The

rem

ainin

gro

ckan

dove

rbre

akco

nditio

n(z

OV)

Cla

ssI

IIIII

IVV

VI

VII

IIX

Desc

ription�

There

issm

ooth

wal

lw

ithout

dam

age

and

crac

kin

g

�T

here

issm

ooth

wal

lw

ith

low

crac

kin

g

�T

here

are

a

little

bac

kbre

ak,

sidebre

akan

d

tensi

on

crac

k

�d b

a<

Bor

d si<

S*

�d b

a<

Ban

d

d si<

S

�d b

a<

B

and/o

rd s

i<S

�d b

a>

Bor

d si>

S�

d ba>

Bor

d si>

S

�N

ot

nece

ssar

y

tofa

cesc

alin

g

�N

ot

nece

ssar

y

tofa

cesc

alin

g

�D

rilli

ng

loca

tion

isre

lative

lysa

fe

�D

rill

equip

ment

loca

tion

is

rela

tive

ly

safe

�D

rill

equip

ment

loca

tion

is

rela

tive

ly

dan

gero

us

�D

rilli

ng

and

bla

stin

gar

enot

poss

ible

but

rock

extr

action

carr

y

out

by

load

ing

equip

ment

�Fa

cesc

alin

gby

load

ing

equip

ment

are

not

poss

ible

�Fa

cesc

alin

gby

load

ing

equip

ment

isnot

poss

ible

�D

rilli

ng

loca

tion

issa

fe

�Fa

cesc

alin

g

by

load

ing

equip

ment

iseas

y

�D

rilli

ng

and

face

scal

ing

by

load

ing

equip

ment

are

rela

tive

lyeas

y

�D

rilli

ng

and

face

scal

ing

by

load

ing

equip

ment

are

rela

tive

lydiff

icult

�D

rilli

ng

and

bla

stin

g

are

not

poss

ible

but

rock

extr

action

carr

y

out

by

mech

anic

al

equip

ment

asdoze

r

�D

rilli

ng

and

bla

stin

g

are

not

poss

ible

but

rock

extr

action

carr

ied

out

by

mech

anic

al

equip

ment

such

asa

doze

r

z OV

13

58

11

14

17

20

*B:burd

en,S:

spac

ing.

Figure 2. A typical overbreak condition and the remaining rock

after blasting.

Taji et al. 5




station, power house, power main lines, power station;(5) the presence of the historical construction, the envir-onmental protected location and their distance from theblasting site and related regulations; (6) yearly weatherconditions and their variances and degree of alter-ations; (7) general direction and position of the wind;(8) flexibility and changeability of mine facilities loca-tion and access ways; (9) bench width; (10) dilution andore grades limitations and the blast block selectionbased on these factors; (11) required degree of the cer-tain block blasting to provide production schedulingobjectives and selective mining; (12) flexibility of pro-duction constraints and blasting time scheduling underdifferent atmospheric conditions; (13) general shape ofthe pit and adjacent mining sites constraints; (14) pre-sent mine equipment; (15) Capability of equipment toreach a safety zone; (16) bench and pit slopes stabilityconditions in blasting practices (Pal Roy, 2005).

The blasting site sensitivity is classified into threemajor groups: usual sensitiveness, relatively sensitiveand sensitive. According to the above-mentioned 16 fac-tors, usual sensitiveness shows that the facilities loca-tions, the main roads, power and energy main linesand urban distances from the blasting site are suitable.The in-pit roads are flexible and changeable. There areno air noise limitations because the suitability of dormi-tory and urban areas are probable. The yearly weatherconditions are desirable. The drilling, loading andhauling equipment usage are probable. The productionscheduling has high flexibility in bad climate conditions.The bench and pit slopes stability conditions are goodand predictable. Blending reasons are not significant.

The environmental influences and impacts of theblasting operation are classified into three positionsi.e. acceptable, relatively acceptable, and relativelyunacceptable, which are indicated in Table 7.

Table 8 shows the blasting operations’ environmen-tal considerations (zEN), based on the considered fac-tors in the environmental outputs of blasting operationand the sensitivity degree as well as blasting site condi-tions (usual, relatively sensitive and sensitive).

2.1.7. The presence and condition of misfire (�MI). If misfireoccurs, only few employees shall remain in the blastedsite. The blaster shall determine after each blast that nomisfire has occurred. Under most conditions the safestway to dispose of a misfire is ‘reshoot’. The misfireprognosis ability is of two types: (1) properly, certainor suitable; (2) improperly, uncertain or unsuitable.Table 9 shows the misfires conditions are classifiedbased on prognosis ability, the misfire number andposition.

2.2. Structure of the blast results matrix [�]

The blast results matrix is constructed by means of theblasting outputs. Let us suppose that the numbers ofblast blocks and the blast results are m and n, respect-ively, then the matrix will be a m� n matrix, the jth rowof which is occupied by seven blast results for the jthblast block. In fact, �j is the sum of zFR, zMU, zOV, zFL,zBO, zEN and zMI. The possible minimum and maximumzj are 7 and 140, respectively. The seven blast results andtheir matrix can be shown in the following form:

�½ � ¼

�FR1�MU1

�OV1�FL1

�BO1�EN1

�MI1

�FR2�MU2

�OV2�FL2

�BO2�EN2

�MI2

�FR3�MU3

�OV3�FL3

�BO3�EN3

�MI3

..

.::::

�FRm�MUm

�OVm�FLm

�BOm�ENm

�MIm

266666664

377777775

¼

�1

�2

�3

..

.

�m

26666666664

37777777775

ð1Þ

As shown in Table 10, the overall blast results valuesare classified into five classes.

3. Relative evaluating of blast operation

3.1. The performance matrix [P]

To consider weight and importance of each the blastresults introduced the performance index (Pj). If themeasured specific mine unit operations index in thejth blast block is Suoj (kg:hr=m8), the performanceindex can be defined as

Suoj ¼ Scj:Sdj:Slj ð2Þ

pj ¼SuojPmj¼1 Suoj

j ¼ 1, 2, . . . ,m ð3Þ

Figure 3. A typical bench floor and toe remaining rock.





Tab

le5.

The

bench

floor

and

toe

conditio

n(z

FL)

Cla

ssI

IIIII

IVV

VI

VII

IIX

IXX

II

Desc

ription�

Bench

floor

isle

vele

d

�B

ench

floor

isle

vele

d

�B

ench

floor

isle

vele

dan

d

its

surf

ace

is

pla

nar

or

undula

ting

�B

ench

floor

isle

vele

dan

d

its

surf

ace

is

rough

�B

ench

floor

isle

vele

dan

d

its

surf

ace

is

rough

�B

ench

floor

isunle

vele

d

�B

ench

floor

isir

regu

lar

and

unle

vele

dw

ith

har

dto

e

�B

ench

floor

isunle

vele

dan

d

its

surf

ace

is

undula

ting

�B

ench

floor

isunle

vele

dan

dits

surf

ace

isro

ugh

�B

ench

floor

isunle

vele

dan

d

its

surf

ace

isst

epped

�B

ench

floor

leve

ling

isnot

nece

ssar

y

�Load

ing

equip

ment

pro

duct

ivity

isve

ry

good

for

floor

dig

ging

and

load

ing

�H

F<

1/ 4

J�

HF<

1/ 4

J�

HF¼

(1/ 4�

2/ 3

)J�

HF¼

(1/ 4�

2/ 3

)J�

HF>

2/ 3

J�

HF>

2/ 3

J�

HF>

2/ 3

J�

HF>

2/ 3

J

�T

here

isno

bench

floor

bre

akin

g

�B

ench

floor

bre

akin

gis

low

�Load

ing

equip

ment

pro

duct

ivity

isgo

od

for

dig

ging

and

leve

ling

�B

ench

floor

extr

action

is

not

nece

ssar

y*

�B

ench

floor

Extr

action

and

dig

ging

carr

ied

out

by

load

ing

equip

ment**

�D

iggi

ng

and

leve

ling

by

load

ing

equip

ment

is

diff

icult

�N

ece

ssar

yto

dig

ging

and

leve

ling

by

doze

r

�N

ece

ssar

yto

dig

ging

by

doze

r

�To

elo

cate

d

betw

een

hole

s

�To

elo

cate

d

betw

een

hole

s

and

infr

ont

of

hole

s

�T

he

dri

lling

pro

duct

ivity

is

good

�T

he

dri

lling

pro

duct

ivity

is

rela

tive

lygo

od

�Load

ing

pro

duct

ivity

tocl

ean

up

islo

w

�Load

ing

pro

duct

ivity

to

clean

up

islo

w

�B

ench

floor

leve

ling

by

shove

l

isdiff

icult

�B

ench

floor

leve

ling

isnot

poss

ible

by

load

ing

equip

ment

but

bla

stin

gis

nece

ssar

y

�B

ench

floor

leve

ling

isnot

poss

ible

by

load

ing

equip

ment

but

bla

stin

gis

nece

ssar

y

z FL

13

57

911

13

15

17

20

*Bench

floor

leve

ling

could

be

carr

ied

out

duri

ng

bott

om

blo

ckbla

stin

g.

**It

may

need

tobe

bla

sted.

Taji et al. 7




wherePj is a dimensionless numerical value, and the sum-mation ofPj for all blast blocks is 1. For a relative assess-ment, the use ofPj can reduce the effects of themeasuringerrors on the possible ODMvalues. Here Scj, Sdj, and Sljare specific charge (kg=m3), specific drilling ðm=m3Þ andspecific loading ðhr=m3Þ, respectively. These are mea-sured based on the volume of in situ rock in the jthblast block. In reality, specific loading is arrived by divid-ing the loading equipment total access time (hours) to thetotal volume of the jth blast block (m3).

For m number of blast blocks and n number of theblasting results, the specific mine unit operations indexratio or performance matrix [P] is a 1�m matrix, i.e.

P½ � ¼ P1 P2 � � � Pm

� �ð4Þ

3.2. The ODM matrix [O]

By multiplying the blast results matrix [z] and the per-formance matrix [P], the ODM matrix [O] can be com-puted as

O½ � ¼ �½ � P½ � ð5Þ

and a subsequent result is

O½ � ¼

o11 o12 . . . o1m�1 o1mo21 o22... . .

. ...

om�11 . . . om�1m�1om1 . . . omm

266664

377775

ð6Þ

where

ODM1 ¼ O11 ¼ �1P1

ODM2 ¼ O22 ¼ �2P2

..

.

ODMm ¼ Omm ¼ �mPm

8>>><>>>:

ð7Þ

The m number of elements along the leading diag-onal of the matrix [O] are the ODM values of the mnumber of blast blocks. A larger ODM value for a blastblock indicates a lower optimization effect of the blastblock. Table 11 shows the ODM classification and their

analysis. The ‘r’ value in Table 11 is calculated asfollows:

r ¼U� L

5ð8Þ

where U and L represent maximum and minimum Pj �j ,respectively.

4. The ODM application

4.1. Chador Malu mine information

The Chador Malu mine is located in Central Iran,120Km north-east of the city Yazd. The mine is con-nected with the national railway which is used for trans-porting iron ore to Isfahan Steel Plant. Chador Malumine includes five ore bodies. An estimated reserve isabout 300 million tons (NGDIR, 2009). The northernore body with 235 million tons of mineable deposit hasbeen in operation since 1995. Chador Malu is one ofthe major producers of iron ore concentrate in Iran.The annual production is 22 million tons including10 million tons of ore and 12 million tons of overbur-den and waste (R&D Department of Chador MaluMine, 2009).

4.2. The Chador Malu mine blasting parameters

The blasting accessories contain mostly detonatingcords and the rarely used nonel system. The explosivesare ANFO (dry hole) and slurry (watery hole).

4.3. ODM criteria

4.3.1. The BBSR. The BBSR of the nine Chador Malumine blast blocks classified as class 2 are as shown inTable 12.

4.3.2. The blast results matrix [�]. The numbersof blast blocks and the blast results are 9 and 7, respect-ively. In fact the blast results matrix will be 9� 1 asfollows:

�½ � ¼

8 4 11 9 9 5 34 4 3 5 3 2 18 1 8 9 7 5 112 12 14 11 11 10 312 10 17 13 13 12 118 12 8 7 5 2 14 1 5 3 3 2 18 12 11 9 7 5 58 7 5 9 9 6 3

26666666666664

37777777777775

¼

492239738843195747

26666666666664

37777777777775

ð9Þ

Figure 4. A typical muckpile area and location of the boulders

(after Jimeno et al., 1995).





Tab

le6.

The

clas

sific

atio

nof

bould

ers

and

ove

rsiz

ed

conditio

ns

(zB

O)

Fact

ors

Cla

ss

III

III

IVV

VI

VII

IIX

IX

MB

O%

None

<3

3–5

3–5

3–5

5–10

5–10

>10

>10

Dela

yat

the

crush

er

None

None

Very

low

Very

low

Low

Modera

teM

odera

teH

igh

Very

hig

h

Dela

yat

the

load

ing

equip

ment

None

None

Very

low

Low

Modera

teH

igh

1H

igh

1H

igh

1Very

hig

h

Seco

ndar

ybla

stin

gN

one

Unnece

ssar

yU

nnece

ssar

yO

KO

KO

Knece

ssar

ynece

ssar

ynece

ssar

y

Situ

atio

nof

bould

ers

inth

em

uck

pile

None

Floor

&

front

Eve

ryar

ea

Eve

ry

area

Inte

rior

and

top

Eve

ry

area

Eve

ry

area

Most

ly

top

Eve

ry

area

Dig

ging

conditio

ns

Exce

llent

Eas

yR

ela

tive

ly

eas

y

Rela

tive

ly

eas

y

Modera

teR

ela

tive

ly

diff

icult

Rela

tive

ly

diff

icult

Diff

icult

Diff

icult

Load

ing

opera

tion

safe

ty

Exce

llent

Very

good

Very

good

Good

Rela

tive

ly

safe

Rela

tive

ly

safe

Rela

tive

ly

dan

gero

us

Dan

gero

us

Dan

gero

us

Bould

er

bre

akin

g

meth

od

None

By

load

ing

equip

ment

By

load

ing

equip

ment

Seco

ndar

y

bla

stin

g2Se

condar

y

bla

stin

g3O

nly

seco

ndar

y

bla

stin

g3

Seco

ndar

y

bla

stin

g4Se

condar

y

bla

stin

g4Se

condar

y

bla

stin

g4

Extr

action

lost

tim

e

due

tose

condar

ybre

akag

e

None

None

Very

low

Low

Modera

teH

igh

Hig

hVery

hig

hVery

hig

h

Pro

duct

ivity

of

load

ing

opera

tion

Exce

llent

Very

good

Very

good

Good

5R

ela

tive

lygo

od

6M

odera

te6

Low

7Very

low

Very

low

Pro

bab

ility

of

the

bould

ers

bre

akag

ein

the

next

bla

stblo

cks

None

None

None

Hig

hM

odera

teH

igh

Modera

teLow

None

Flexib

ility

of

bre

akag

e

meth

od

tom

uck

pile

extr

action

None

Very

good

Very

good

Good

Modera

teR

ela

tive

ly

low

Low

Low

Very

low

z BO

13

57

911

13

17

20

1Load

ing

opera

tion

vari

able

dela

yis

hig

h.

2O

rby

load

ing

equip

ment

or

mech

anic

alm

ean

s.3Fi

rst

bould

ers

should

be

colle

cted

and

subse

quently

use

din

the

seco

ndar

ybre

akag

em

eth

od.

4T

hey

need

two

or

more

bre

akag

em

eth

ods.

5Load

ing

fixed

tim

eis

less

than

5%

usu

altim

e.

6Load

ing

fixed

tim

eis

5–10%

usu

altim

e.

7Load

ing

fixed

tim

eis

more

than

10%

usu

altim

e.

Taji et al. 9




Table 7. Classification of the environmental influences and impacts of the blasting operation

Characteristics

The environmental influences and impacts of the blasting operation

Acceptable Relatively acceptable Relatively unacceptable Unacceptable

Production delays None Yes1 Yes4 Yes9

Facilities damage None None Permissibly High

Flying rock Permissible limit Very low Troublesome5 Very high10

Air noise Permissible limit Very low Relatively high6 High11

Ground vibration permissible limit Permissible limit More than permissible High

Bench stability Any problem Problem2 Troublesome6 Very poor12

Slopes stability Any problem Problem3 Troublesome8 Very poor

1These delays increase the direct costs for maximum amount of 10 percent of expected costs but these production delays are compensated by the end

of working shift.2Safety factor of bench and slopes stability is reduced locally.3There are not slope wedges and failure-intensive problems.4These delays cause increasing direct costs to a maximum of 30% of expected costs.5It is necessary to clean up roads from fly rocks.6The air noise is more than the permissible limit and there is ground vibration problems on the nearby building. The amount of dust is considerable.7Safety factor of the bench and slopes stability is reduced.8There are slope wedges and failures problems.9There are production delays and the equipment efficiency is reduced, especially hauling equipment, severely (its delay is more than two working shifts).

The delays give increasing direct costs of more than 30% extraction expected costs.10The roads are obstructed. The personnel injuries are intensive.11The air noise and ground vibration problems are severe.12There are bench and slopes failures and wedges severe problems.

Table 8. The blasting operation environmental considerations based on the blast site sensitivity (zEN)

The blast site sensitivity and conditions

The environmental influences and impacts of blasting operation

Acceptable Relatively acceptable Relatively unacceptable Unacceptable

Usual 1 5 10 16

Relatively sensitive 2 6 12 18

Sensitive 3 7 14 20

Table 9. The misfires conditions (zMI)

Misfire conditions Class

Prognosis ability

Suitable Moderate Unsuitable

Misfire absence I 1 3 5

Few in number and/or concentrative II 9 11 13

Scattered and/or numerous III 16 18 20

Table 10. The zj classification and their analysis

Class I II III IV V

zj <25 25–50 50–75 75–100 >100

Condition Very good Good Moderate Weak Very weak





The seven blast results adapted degree and the over-all blast results value for the nine blast blocks in theChador Malu mine are shown as radar diagrams, asdisplayed in Figure 5.

4.3.3. The performance matrix [i]. The performancematrix is computed using Equations (2), (3) and thespecific charge, specific drilling and the specific loadingmeasured based on the volume of in situ rock in thenine blast blocks. Table 13 shows the specific mine unitoperations and performance indexes in the ChadorMalu mine. The performance matrix [P] is a 1� 7matrix and can be established as follows:

4.3.4. The ODM values. By substituting Equations (9)and (10) into Equation (5), the ODM matrix [O]can be obtained. As specified in Equation (6), theODM values for the nine blast blocks are the nine elem-ents placed along the leading diagonal of the matrix[O]. The ODM and the overall blast results values fornine blast blocks in the Chador Malu mine are shownin Table 14.

4.4. Comparison analyses of the nine blast blocks

For convenience of comparison, the performance index(Pj), the overall blast results value (zj) and ODM valuefor the nine blast blocks in the Chador Malu mine areshown as radar diagrams. These are shown in Figures 6and 7. As a result, the following information can bededuced.

1. The minimum ODM value is for the blast block7. Also the minimum Pj (P7¼ 0.065) and �j(z7¼ 19) is obtained for this block, i.e. the overallblast result and the efficiency of other operations(drilling and loading unit) are very good. Thismeans that the minimal ODM value for theseblast blocks have a direct relation to their specificunit operations and blast results. Thus, it showsthe performance, condition and results of otheroperations will affect the rational analysis ofblast results.

2. The z2 and z7 are very good but the z3 and zFR3

are good. In fact, by considering the efficiency ofdrilling and loading operations and blast results,the ODM class of the blast blocks 2, 3 and 7 is I.This means that these blocks indicate very goodcondition.

3. The ODM class of the blast blocks 4 and 5 is V, i.e.the requirement degree to optimization of theseblocks is very high.

4. The degree of fragmentation of the blastblocks 1 and 6 are good. The loading system inthese blast blocks are a loader. The loaderaccess height is lower than the bench height in thismine. For this reason, the ODM classes of the blastblocks 1 and 6 are, respectively, III and IV. Thisindicates that the better fragmentation would givebetter overall blast results and mining operationefficiency.

5. Conclusions

With respect to the above discussion, it seems that aquantitative evaluation method is necessary and criticalin order to analyze a blasting operation. Consequently,the present research proposes the concept and ratingprocedure of the effective blasting results. The ODMprocedure is helpful because it enables enhanceddesign and optimization as necessary for blasting

Table 11. The ODM classification and their analysis

ODM class I II III IV V

ODMj L to Lþ r Lþ r to Lþ 2r Lþ 2r to Lþ 3r Lþ 3r to Lþ 4r Lþ 4r to U

Conditions Very good Good Relatively weak Weak Very weak

The requirement degree

to optimize

Very low Low Relatively high High Very high

Table 12. The BBSR of the 9 Chador Malu mine blast blocks

Number of

blast block 1

2 and

9

3 and

7 4 5 6 8

S1 0 0 0 þ5 �3 �2 þ5

S2 0 þ5 0 0 þ5 0 0

S3 þ3 þ3 þ5 þ3 0 þ5 þ5

S4 þ3 þ3 þ3 þ3 þ3 þ3 �3

BBSRj þ6 þ11 þ8 þ11 þ5 þ6 þ7

P½ � ¼ 0:109 0:075 0:076 0:145 0:115 0:192 0:065 0:134 0:089� �

ð10Þ

Taji et al. 11




Table 13. The specific mine unit operations and performance indexes for nine blast blocks in the Chador Malu mine

No. Scjkgm3

� �Sdj

mm3

� �Slj

hrm3

� �Suoj

kg:hrm8

� �pj

1 0.867 0.0309 0.0141 0.000378 0.109

2 0.847 0.0269 0.0114 0.000260 0.075

3 0.796 0.0265 0.0124 0.000262 0.076

4 0.910 0.0320 0.0172 0.000501 0.145

5 0.826 0.0265 0.0181 0.000396 0.115

6 1.094 0.0361 0.0168 0.000663 0.192

7 0.855 0.0278 0.0094 0.000223 0.065

8 0.917 0.0319 0.0159 0.000465 0.134

9 0.850 0.0283 0.0128 0.000308 0.089

Note: The loading operation for the blast blocks 1 and 6 are carried out by a loader.

Table 14. The ODM and the overall blast results values for nine blast blocks in the Chador Malu mine

The degree of fragmentation The overall blast result ODM

No. zFR Class Condition zj Class Condition Value Class Condition

The requirement

degree to optimize

1 8 III Good 49 II Good 5.3 III Relatively weak Relatively high

2 4 II Very good 22 I Very good 1.7 I Very good Very low

3 8 III Good 39 II Good 3 I Very good Very low

4 12 IV Moderate 73 III Moderate 10.6 V Very weak Very high

5 12 IV Moderate 88 IV Weak 10.1 V Very weak Very high

6 8 III Good 43 II Good 8.3 IV Weak High

7 4 II Very good 19 I Very good 1.2 I Very good Very low

8 8 III Good 57 III Moderate 7.6 IV Weak High

9 8 III Good 47 II Good 4.2 II Good Low

Figure 5. The blast results adapted degree to the overall blast result value for nine blast blocks in the Chador Malu mine. (The

dashed lines are the overall blast results value.).





engineering. The key conclusions that can be drawnfrom this paper are as follows:

. By integrating the theoretical analyses, experiencesand monitoring, the blast results can be classified.The assigned values and their changes can be con-veniently analyzed in the form of matrices.

. The ODM provides an efficient evaluation mechan-ism for the main outcome of the blasting.

. To define and assess of the ODM values, the blastblocks should be divided into different classes basedon blast block situation rating and considering blastworking conditions.

. The seven main blast results considered include frag-mentation degree, muckpile, overbreak, bench floorand toe conditions, the boulders, the environmentalconsiderations and condition of misfires. Theyshould be classified and rated accordingly.

. In this procedure, the blast results and the efficiencyof other unit operations are analyzed together.

. The specific charge, specific drilling and specificloading indexes should be recognized as one of theobjective criteria for the ODM assessment.

In a nutshell, the ODM can help design engineers torecognize the optimization demands of each blasting atdifferent mining conditions. Using this approach, theactual evaluation of the blast results can be achievedin an open pit mine.

Acknowledgements

We are thankful to the Khandagh Tech. & Eng. Companyand the Chador Malu, the Choghart, Gole Gohar mine, Iran

for their crucial support during this study. We express ourgratitude to A Mahzun, H Mahmudabadi and staff and tech-nicians of Khandagh Co. The authors are also indebted toEng. SH Hoseinie and Dr F Sereshki of Shahrood University

of Technology and Eng. A Afsharian of the Chador Malumine for their valuable suggestions and help.

Funding

This research received no specific grant from any fundingagency in the public, commercial, or not-for-profit sectors.

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Figure 6. The Pj and zj radar diagram of the nine blast blocks in the Chador Malu mine.

Figure 7. The Pj , zj and ODM radar diagram of the nine blast blocks in the Chador Malu mine.

Taji et al. 13




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Documents

ODM a New Approach for Open Pit Mine Blasting Evaluation (Dr. Taji)