Download - micropile- Jefferis PPT
Minepastebackfill:theuseof
grou
tsat
massiv
escale
Step
hanJeffe
risEnvironm
entalG
eotechnics
Ltd
Step
henWilson
Hambled
onMiningplc
SYNOPSISOFPA
PER
•Selectionof
cementitious
bind
er•Rh
eology
andpipe
flow
•Co
nsolidation
•Bleeding
•Ch
anne
lledbleed
CONVE
NTIONAL
TAILINGS
MAN
AGEM
ENT
•Tailings
minewaste
afterm
illing
•Fine
tailingstypically80
%passing75
μm•Wet
andeasilyliquefiable
•Po
tentialfor
flowslide
s–occurred
toooften
•Typically
retained
with
intailingsd
amso
rlagoon
s•Largearea
ofland
requ
iredwhich
ultim
ately
mustb
erestored
totheenvironm
ent
Taili
ngs
feed
(slu
rry
pipe
line )
Hyd
rocy
clon
e
Und
erflo
wsa
nd
Ove
rflow
fines
Slim
es
Sup
erim
pose
d po
nd
Cle
an w
ater
Dec
ant r
etur
ned
to p
lant
Dam
Dra
in
Phr
eatic
line
With
gra
tefu
l ack
now
ledg
men
t to
Pro
f Tam
as M
eggy
es, B
AM
Sur
face
pas
te d
ispo
sal
Bul
uyan
hulu
-Ta
nzan
iaW
ith g
rate
ful a
ckno
wle
dgen
t to
Pro
f T. M
eggy
es &
Gol
der A
ssoc
iate
s
Sur
face
pas
te d
ispo
sal
Bul
uyan
hulu
-Ta
nzan
iaW
ith g
rate
ful a
ckno
wle
dgen
t to
Pro
f T. M
eggy
es &
Gol
der A
ssoc
iate
s
AZNALCO
LLAR
,SPA
INFAILED
TAILINGS
DAM
Dam
Breach
INSIDE
THEFAILED
TAILINGS
POND
POTENTIALLY
ACID
GENER
ATINGPYRITE
WAS
TE
CEMEN
TEDPA
STEBA
CKFILL
•Co
nvertin
gaprob
lem
into
asset
•Re
turnsa
prop
ortio
nof
tailingsu
ndergrou
nd(m
axim
um~50
%)
•Ce
mentedmassc
anbe
used
forregionalund
ergrou
ndminesupp
ort
•Pastewillno
tstoproof
cracking
•no
tstiffe
noughbu
twillstop
collapse
•Enablesg
reater
prop
ortio
nof
orebo
dyto
berecovered
•Re
ducesd
ilutio
nof
oredu
ringextractio
n•Re
ducesa
bove
grou
ndstorage
PASTEBA
CKFILL
•Water
may
bescarce
somaxim
umrecovery
ofwater
isde
sirableandachieved
throughthickening
orfiltration
•Und
ergrou
nddisposalredu
ceslandtake
andenvironm
ental
risk
•Acementitious
bind
erisrequ
iredform
aterialplaced
unde
rgroun
das
thematerialretains
water
•Mines
areofteninremotelocatio
ns,how
ever
paste
minim
isesb
inde
rreq
uirementscomparedto
othe
rbackfills
•Ch
emicalandph
ysicalprop
ertie
sofm
inetailingsc
anbe
complex
andvaria
ble
•Re
sidualamou
ntso
fmetalssuchas
copp
er,leadandzin
ccankillor
massiv
elyretard
cementset
WITHGR
OUTS
ONESIZE
DOES
NOT
FITALL
REQUIRED
PROPERT
IES–PA
STEBA
CKFILL
•Econ
omyof
who
leprocess
•Minim
umbind
ercontent
•Exploito
ravoidtailingsc
hemistry
•Minim
umwater
content
•Pu
mpability
•Selflevelling
•Bleed/filtration/consolidationminim
al•Pene
trability
–no
tanissue
ALSO
NEEDTO
SELECT
APPR
OPR
IATE
GROUTBE
HAVIOUR
MODE
LS
Und
ergrou
ndMine
Processin
gPlant
Tailings
Concentrate
Filte
ring
Thickening
Mixing
Bind
er
or
Simplified
PasteBa
ckfill
MaterialFlowDiagram
Backfill
Plant
Water
Recycling
Cob
riza
Min
e, P
eru
Past
e Th
icke
ner
Und
erflo
w
Lish
een
Min
e Pa
ste
Plan
tIre
land
MAS
SIVE
THICKENER
PASTEMIXSTATION
TAILINGS
–BINDE
RMIXER
Typi
cal t
hick
er p
aste
bac
kfill
6-7
inch
slu
mp
Gol
d Ta
iling
s –
Seki
sovs
koye
Min
e, K
azak
hsta
n
Typical
tailings
paste
Testing
Prob
ably
willfin
dabe
tter
one
PIPELINEPR
ESSU
REGR
ADIENT
•Pastemustb
epu
mpableas
itmay
have
tobe
pumpe
dsubstantialhorizo
ntaldistances
but
•Minemay
bede
epso
that
thereisalarge
verticaldrop
•Needto
avoidcavitatio
nandfree
fallof
paste
•Otherwise
severe
damageto
pipe
worketc.
d4
LPw
PIPELINEPR
ESSU
REGR
ADIENT(P/L)
Functio
nof:
shearstressa
twall
w•
pipe
diam
eter
d
BASICRH
EOLO
GY–BINGH
AMMODE
L
bb
Shearstressat
wall
wisafunctio
nof:
•yieldstress
•plastic
viscosity
•shearrate
PRED
ICTIONOFWALLSH
EARSTRE
SS
•Standard
equatio
nexist
forB
ingham
mod
el•bu
tinpracticewalllayer
develops
•Walllayer
ismoreflu
id•Effectismorepron
ounced
insm
allerp
ipes
•Invalidates
simpleBingham
mod
elfora
llgrou
ts!
•andanyothe
rsinglematerialm
odelwhich
considerso
nlybu
lkflu
id•Forp
umping
pressure,needto
consider
onlythewalllayer
ROTATIONAL
VISCOMETRY
•Co
uldtryto
match
shearrates
viscom
eter
pipe
•Co
mplex
andmay
notrep
resent
wallcon
ditio
ns•So
setp
eriphe
ralvelocity
ofshearvane/b
obto
averagelinearv
elocity
inpipe
,Vp
•Use
largediam
eter
cup(in
finite
sea)
pV
dNTestvane
orbo
bin
cupof
grou
t
SHEA
RSTRE
SSONBO
B
Whe
reM
isthetorque
onthebo
b
2DhM2
r
rw
assume
dhDM
8LP
2
Hence
PIPELINEPR
ESSU
REDR
OP
•Shearstresso
nbo
bat
approp
riate
rotatio
nal
speeds
givesa
nindicatio
npu
mping
pressure
•Quick,verysim
ple,no
need
tode
velopfull
rheo
logy
form
aterial
•Provides
aratio
nalbasisforselectio
nof
viscom
eter
rotatio
nalspe
edforo
peratio
nal
QA/QC
•Metho
dology
canbe
refin
edforo
ther
materials/a
pplications