Paper To Be Presented

PAPER TO BE PRESENTED

-t

SYI4POSIUM ON THE ASSAYING

organised

INSTITUTE

SOUTH AFRICAN

at

on

AUTO}4ATED SOLUTION

OF PRECIOUS

by

OF ASSAYERS & ANAIYSTS

Johannesburg

16 Sentember

TAILS

ANALYSIS

1986

ON IIARMONY GOLD MINE

by

E.

* Metallurgical Harmony Gold

METALS

KIRBY,*

BSc

Superintendent, Services, Miningr Company Limited

(Hons)

PhD

AUTOMATED

TAILS

SOLUTION

ANALYSIS

ODJ HARI4ONY GOLD MINE

recovery

process

INTRODUCTION

a

gold

from

the Crowe-Merril cyanide

d.eaerated

years

recent

automatic

solution

automatic gold \' jl'the period T:Eboratories South African

various analyser

are

still

analyser 1965 to

plants.

Anglo

All

analysers

of

these

of

equipment.

in

the

analyser

to

of

reliable

solutions.

tails

of

installation

work

led

to

the

of

the

Gold t4ines,Further

(AARL) resulted

availability

cornmerical

on

origirtal

j11 Novernlcer 1978 at

was

House

Corper

were installed

versions

modified

Laboratories

j_nstallation

f irst

units

ERPMand Blyvooruitzicht

Research

of

in the

an Ergo

the

OLGA

1983.

of

sensitivity

electrothermal

use

value

by Rand Mines

A nurnber of

1969-.

preconcentration

desired

generally

is

has been the

was developed

were desi,gned around

units Gold

achieve

the

Arnerican

jnnrnrraA :n:1rrca1. Ttreir ) Conti-nued Plant-. Gold series

i:r hiqh

such losses

Extensively at

working

by

development

the precipitation

analysers.

tails

first

T'he

caq result

key to preventj-ng

the

is

operation

Ttris

solution.

problems

or mechanical

chemical

but In

qi-en in

.rifical

flame

atomisation

by solvent

extraction

0,01 ppm

j.n

Au

atomisation

atomic

necessary

was

solution.

developed

was

absorption

The

to first

Ivljrttek

by

in

2

Increased

7982'. hro-^n^an

Fr:l-

mechanical

Atomiser

Late

i an

cl- a^

T alravr ^i rroer .r a er !

with

difficulties

personnel

were to

i-rr

the

discussing

overcome

1983

eliminated

sensltivity

it

Merriespruit

Gold

considering

various

ttre

l- h i q

,

sample use of

for

need

*: Aur "r a* n, l--a g e

probabLy

was

presentation. the

new

troublesome

the

Durilg

Varian

GTA95

of f set

by

Mj-ntek

1983 Graph.ite

T\rbe

such problems.

was Plant

decided of

alternatives,

to

jrtstall

Harmony cold the

an Miling

i-n-house

autorlatic

analyser

Company

d.evelopment

Limited..

of

on

the After

a new syst.em was

aFproved.

DESfQ'l/.

. .

DESIGN

OF THE AUTOMATED SOLUTION

A Mintek

demonstration

installation.

The

linked

to

At

same time,

the

control

other

for

the

The

control

coryuter

dependant

of

sampling,

Stellar

software'

was eivisaged.

on line,

remote

part

components.

of

It

rnade

atomic

for

on-Iine

an interface

and data

capacity

to

and

collection. monitor

with

and

design

rake

unit)

of

intelligence

same time,

a

togrether

analyses

L4z capital

cost

graphite would

and.

provided

these

operatj-ng

and the

operations

artificial

that

was to

this

mainlsnance

v/as a plastic

would

rnaximise

minimise

spares.

sampling

jl.stallation

up the

of

of plant

(AA) machll.e,

and sequence

philosophy

thought of

part

availalriJ-ity

on

be

tails

by computer

advantage

over

from AARL was estirna1.6.

the

was

the

the

lj-ne or circulating),

absorption

j-n the Carpentersrworkshop

which

control

moni-torJlg

off

(precipitation

At

good availabil-ity

polyethylene

with

sufficient.

couputer

frequency

system,

an OLGA system

specially

suita-bility

be fitted

ad.vantage of

units

filter

A flexjJcle

took the

The

values-

An i-mportant

allowing

jlvolved

the

(GTA).

on

purchasing

could

would. have

new analyser

concept

atomiser

items

thus

(precipj-tation

cond,itions

allow

eguiproent

showed. their

equipment

products-

tube

analysis

the

prod.ucts

Varian

a micro-computer,

Proposals

with

of

A}]ALYS]S (ASTA) SYSTEM

TAILS

This

covered

i_n a stepwise

fashion

was

Further

standard time

turned. out,

on the lrine.

are

use of

d.evelopment

As it

weir.

the

an6

the

only

rnachined

from

details

of

the

fur a prevj_ou= p.p.r4.

DEVELOPMENT OF ASTA The

system

year. in

was

developed,

The AA and GTA were acquired, the

1984.

laboratory, Initially

they the

ir

j_nstalled

were

sampling

late

valves

over

a period

of

Novernber 1983. After

on lile

and the

at

one

bench testing

Merriespruit

analysis

ah'out

in

January

equj_pmen! were operated.

by a sequence controller.

The next

development

programmjng,

this

Pressure

switches

monitor

the

to

the

respond. its

fi'.al

took

By the version.

jI

of

arrival

over

were then

status

computer

was the

Septeiulcer

Alr

from

installed,

stellar

end of

the

the

the

jl

l4ay 1984.

controller

on pneurnatj-c valve signals

1984 and the control

design

computer

sequence

filters.

1984 the of

of

from

software software

concepts

were

After

in

June

actuating

these

extended

some |gg4.

lines,

to

were corruunicated, to

had. developed.

allow

ASTA

virtually

to

satisfied..

Inj-tially/.

to

..

machine was standardised

Lhe

Initially value

about

0,6.

about

two minutes.

the

Ttre time

Limes of

q^ -r- r1q- -l-yi r r r . ^

rT u+

-.

wds th€D

is

in drying

each.

At

now standardised

0,10 ppm Au,

EXPERIEI{CE

system

grj-m

struggle.

faults

which

machine

from

the

suppliers

What

was

thought

intermittent

fault

1985 when the

In

the

with

last

gold

have

benefits

their

barren

O,OO2 to

0,020

process

with

fbr

limit

upper

were having

solution,

take

about

about

any

allowing

sequence

uses

one mj-nute Although

0r9.

saLisfying

January

by trial

1984

Level

Lhis

were disturbed

Lhe.needs

of

with

an

of

and error,

average

availability

by a collection

Maintenance

final

although

a

was

of

software

for

requirements

the

to

confidence.

bug actually

This

was only

module was replaced.

least

capital

cost

Tttis

pLant for

allows

Many minor

level

the

GTA

support

technical

the

operation. being

put

them to

incidents

out

rectifj-ed

at

the

less

a nunber

one occasion of

turned

then of

ASTA has averted

On at

routine

Since

an acceptable

years,

tur preparation

values.

software

the AA machine.

in

covered

circulated

greater

to be the

precipitation.

being

to

check was

was good.

two and a half

worthwhile

analyses

since

stoppages.

has d.ecreased. to

easily

of

analysis

measured is

Achieving

operations

were learned

keyboard

frequency

out

94%.

caused frequent

AA

gold

The new

comes closer

continuously

than

Early

and

ppm.

and ind.ividual

absorbance zero

range

actions

control

a O,10

At

WITH ASTA

of better

availability

if

the peak absorbance

operated

has

tell

with

the new program

in precision, \. operatino staff.

The

to

the

above the

were well

0,11 ppm.

and ashj-ng times

poorer

OPERATING

values

impossiJcle

the range 0,01 to

shorLer

the

all

trouble

in

solution.

was not popular

arrangement

the

ar

caliJcration

analyses

accurate

However,

in

analyses

each analysis,

Reasonably

management;

rnachine

for

taken

ppm Au were possjlcle.

The

sequence used gave a measured atomic

analysis

this

a 0,020 ppm gold

with

the

than

the

end of

of

rnjor

resultilg

saving

would

are

also

units

ASTA repeated.Iy

wiLh precipitation

cfral

faster are

|

/

week.

incidents

There

on lj-ne

an

call-

once per

When precipitation

be brought

be

maintenance

installati-on.

on line,

to

are

checks

and with

averted

by

small

supplementary

of

additions

ad.dj-tion has decreased. by 0,015 ^nFreJ-

innq

Maqf

plant

normal

k g p e r m 3 of

imnarl-anflrz

operation)

At

zj-nc.

the

solution

treated

averag:e solutj-on

l-ho

the

same time,

overall

due to

tails

zinc

improved. (during

value

by 0 , 0 0 3 p p m .

has decreased

THE ECONOMIC ASPECTS OF ASTA OPERATION Ttre

Merriespruit price

gold

at

R540 per

about

worth

annum.

so payback

A

estinnted, Iife

of

the

rha !.^

m=inr tr^*i^^i

i)

-^

of

a Suitable

control

and

which

location

11t

they

typical

of

Th_e Si-mplicity Individual flow

cost

consunnble

have

a

zinc

which

is

ASTA have been estimated

R732 per

or

day

is

R267

per

180

approxinntely

shown in

Table

and rnajltenance presenL

1.

R120 000

T'his has been

requirements

years

of

operation,

contributed

to

over

the

day costs.

TO THE SUCCESSFUL OPERATION

Location

is

s u c c e s s fJr!r l

OF

possible

it

is

sr

n v !n / ee ! ret-innq

THE

to

ASTA

identify Tr r h t s e q-c s

,

m u qa ), v

Stellar

controlled

pump and susp for a 12,5 rrn

sample

streams

of

these

solenoid to

from

in

office

brick

plant..

Lhe

humidity

dust,

a

fn

and vjlcration

this which

Sarqpling Sstem:

tails

The

required,

the

samples,

down 25 mm pipes

bulk

are housed

environment.

Solution

filter

Instrumentation:

separate

away from

a g'old plant

the

the

equipment

completely

are well

of

for

analysis

contj-nuously

the

is

applyingr

Iocated..

of

gives

-ollows:

buildirrg

are

around

of

in

a

sj:< months.

CONTRIBUTED

which

is

costs

value

in barren

At

day.

€

Choice The

within

on two and a half

€:nrn-s

operating

saving

and, then

FACTORS V\ErrCH HAVE INSTALI,ATION

improvement

a new ASTA installation

average

per

solution

must be added tJ-e saving

operatilg

daily

installation

Lookj-ng back

of

of

6 000 tons

0,003

The present

cost

by takjng the

of

the

To this

be achieved

would

breakdown

gram,

day so the net

Ttre present

about

treats

day.

R32O/day.

per

R12B

R30 per

of

of

saving

Plant

flow

to

sample

plus

tJe

a coubined

office

streams

then

return

to

the

valve

is

opened to

into

plant.

a 6 mro pipe

barren

sample,

where

the

analyser

flows

out

to

a

level

when an analysis allow

manifold.

a portion and. then

sancpli-ng/. . .

is

is

of

one

to

the

weir

period,

the GTA's sampling

deposits

it

jrr the

flows

weir

iii)

on the GTA's sample platform.

samplilg

to

the

graphite

March

Office. by

or

fialA !

have proved

the

solution

frou

h:rro

at

more adept

the

sampling

Assay office:

the

other

operating

a
! 9 ! u ,

Handled !y

is

irstallations.on

Comparahle

:n:lrrl-inal

Excess

and

sub-sample

rnachine has been ma.intai-ned by

the

metallurgists

litre

flushingr

sump.

disposal

1984

a suitable

a 10 micro

takes

tube.

Routj-ne System Maintenance From

probe

After

Assay

mine

mines have been rraintained

staff.

haA

the

As

ftraa|,ar

specialists

crrmn:l-hrr

Far

the

in

amtinmanf

:nri

problems.

fecognising

Ma.nagement Comrnitment :

iv)

Trha

pc I

nrni

has

\ management.

contilued

f ece ived

this

Without

it

could

support

from

levels

all

of

have floundered.

FUTURE DEVELOPMNTS

go ahead. with

A decision

to

f inalised

i-n August

be virtually

will that

IBM rather

fLra

than

nnmnrrfof

" g J { v u l / g v , \ q Y g

outside

Hewlett

skil ls

to

hafdWafe

and

This

that

is

on the

now on order.

conputer

SOftWafe

aS

a

nrica

the

naaL:ao

was made as a result

at. Merriespruit.

is

of

side

from

is

price

d,ecision ffOm

deal

difficulties

IL was recognised

was

difference

was chosen

dj-fference

fiXorl

Plant

The analysis A minor

equipment

most sigmif icanL

decision

Harmony Gold

at Merriespruit.

Packard the

development

qnecial ist

Equipment

However,

suppli-er.

softw-are

IN

1986.

identical

consideration. latrr

an ASTA installation

thaL

buying

to an

with in

is oft.en an economical nronosition.

CONCLUSION

Ad.vances soLution

i-n technologiy tails

analyser.

have allowed.

the

Compared with

consLruction its

of

predecessors,

an j-mproved automated this

system has the

advantages:

following

tt

is

faster.

approx irnately

AnaLyses,

one minute

calijcrations

artd

zero

each.

LL)/...

checks

take

ii)

It

is

more flexilcle.

the

software

for

the

and can be tailored

iii)

It

is

of

microcorryuter. for

Naked, flames

This

individual

The g:raphite

safer.

heated.

The flexilcility

tube

ttre system is

is

relatively

determined easy

to

by

change

applications.

is

inert

and i-nflau'unable

gas shielded

solvenLs

and electricallli

are not

I

used,.

ACKNOWlEDGEMENT T'he author to

publish

wishes ttris

to

thank

the management of

Rand Mi-rres Limited

for

permission

paper

H(/sc 1i September 1986

.nART.r. / --ry41

.

.

.

1:

L)

A BREAKD*Or/hJ O{ fHE DAIII

Graphite

Ttbes

Nitrogen

and Helium

Gold


4)

Lamps for

Deuterium

q)

7)

8)

R30,00 Gas

R6'00

AA

Backgrround Lamps

Electrodes

6)

oPERATrivqcoFrs

for

the

Furnace

Service balls Suppl -ier

from

Miscellaneous

Spares

the

R 2 I, 4 0

(at R1 0OO per

R33,30

(at

R1 0OO per

lamp)

lamp)

R 0 ,7 0

fnslrumenc

R5,30

Daily Majltenance Labour Travell i_ng Expenses

R1,30

and D1n

n^

R 12 8 , 0 0

capitar ri-se tims

costs'

as werl

as consuna-bles arrd rnaintenance costs, have tended to the (Rand) gold. priceThis has meant that ure payback en such an i'star-ra.ion has rernai,.ed fairry constant. in

step

with

REFERE}JCES

of Gold Tailings Solutions by Atomic Analysis RAPSON, w.S. On-Stream Africa, Research Johannesburgr Chardcer of Mines of South Absorption. 1 9 6 9 . No. 35/69. fnformatory Circular 8 September organisation

z^ )\

The Automati-c and WESSELS, F.W. DH\ua , r.Yl . j VAN DALEN, J.H., Solutions. of Determilation Trace Amounts of GoId in Gold Plant Barren of Mhing and of Johannesburg. Journal the South Afri-can lnstitute June 1980. Metallurgry.

3)

and OMROD, G.T.W. ROBERT, R.V.D., f or Analyser. Randburg, Council October 7982.

GoId M50 .

PERCIVAL, tB.N., of Zjlc Preclpitation Tails at the Autornated Analysis of Mining Company Limited. Merriespruit Section Harmony GoId Mirte l,letallurgical Managers' Ml"lMA Johannesburg. Association, No. I/86, June 1986. Circular i

4)

fhe Development of an On-LjIe Report t'ljleral Technology,