SAIMM Pretoria Branch 8 September 2011Implementation of an Alternative Matte Level Measurement Solution at Lonmin Marikana Smelter Division for Improved Process Monitoring

8 Sept 2011

Presentation :Trevor GoffSenior process Engineer – Hot SectionProcess Division - SmelterLonmin

Presentation overview

√ Introduction√ History√ Burning Platform√ Current type of controls√ Alternative matte level solution phases√ Trial results√ Conclusions√ Current status and results

2

Introduction

• Hatch design

• Three electrodes 27.5MW circular furnace with waffle (copper) coolers

• Dried filter cake fed to the furnace

• Electrical energy supplied to furnace to melt the concentrate

• As concentrate melts, slag and matte phase is formed

• PGM reports with Base Metal sulphides to furnace matte phase

• Settles to bottom of furnace via gravity separation, with the slag on top (lower density)

• Black top condition (unreacted concentrate material)

• Matte, slag and concentrate levels measured using mechanized sounding bar

Mechanized sounding bar

CONTROL

PANEL

RAISE

BUTTON

LOWER

BUTTON

EMERGENC

Y STOP

BUTTON

ELECTRIC

MOTOR AND

CABLE REEL

STEEL

CABLE

SOUNDING

BAR

Burning Platform

5

• Furnace design 170mm • Copper - watercooling elements and superheated matte• Accuracy method• Incidents – ICAM identified seek alternative

What was our situation?

“If you know what the matte level is,

you can CONTROL it”

History

• 2004 Dip tests conducted using magnetic sensor technology

• Results were encouraging, but further development was necessary

• Not much development after 2004

• 2008 Google search engine and came across Agellis

• Started teleconferences, meetings and e-mails

Current Type of Controls/measurement

• Manual sounding • following procedure• skill of the operators• interpretation

Hence, the need for an alternative sounding measurement method

• Matte Level Predictor (MLP)

• Slagging

Alternative matte level solution phase

Agellis 2008

Different options

Decide on one

Phase 2Conceptualization

Phase 1Initial improvement

Phase 3Implementation/Trial

Phase 4Concept Operation

Paint

Al wire

MLP

Enhancements to system

More case studies

Hand over to Operations

Trial date was set

Set up success criteria

Installation of equipment

9

Who is Agellis?• Swedish Company Agellis Group – measurement solutions

• ELIM 3 – molten measurement systems, foaming systems

• Double probe - Temperature, bottom build-up, metal (150 systems)

• Electromagnetic sensor – detects conductivity

• Interested new technology Agellis EMLI ELP

• Principle of measurement is the effect of the presence of conductive materials on an electromagnetic field

• By applying an electromagnetic signal of a particular frequency to a sensor coil embedded in a protected lance probe, it is possible to monitor the effect that occurs when it reaches the highly metallic matte in a furnace

• Sensor optimized to detect only very metal rich materials

Phase 2 – Concept/ Options available

• Dual lance carriage system

• Temperature, build-up, sampling of matte/slag ●●●● Complex and cost●●●● New technology – not proven yet in Sulphide smelting

Option 1

• Lance completed with a sensor probe

• Draw wire - part of the measurement system ●●●● ELP has its own winch and furnace access port●●●● Only matte detection●●●● Length of lance – same as manual sounding lance●●●● Electromagnetic sensor installed in lance tip●●●● High temperature cable connected the EM sensor ●●●● Winch capable of a steady 15m/min. ●●●● In all other respects, the lance was operated in the same way as a traditional sounding bar.

Phase 2 – Concept Phase

Option 2

Decided on Option 2

● 3 day plant trial to be conducted

• No safety incidents or injuries

• No operational downtime

• Clear conductivity changes between slag and matte

• 10 (ten) consecutive measurements (dips)

• A correlation of all sensor measurements

vs manual sounding measurement

Phase 3 – Implementation Phase

Success criteria

☑☑☑☑

☑☑☑☑

☑☑☑☑

☑☑☑☑

☑☑☑☑

☑☑☑☑

Phase 3 – Implementation Phase

• Project execution phase

• meetings between different engineering disciplines and interaction

• Mechanical - type of material, size of motor, placement of motor and all auxiliaries, where to fit the draw wire, etc

• Electrical - do we need to pull extra cables, MCC capacity, size and speed of motor (Volts), lead time, where to put management box, cables for new pushbuttons, etc

• Instrumentation - hardware requirements, installation of UTP cables, view computer, etc

• Other requirements - hole in roof and in upper floor, correct drawings, etc

Safety was the biggest vehicle

Phase 3 – Final installation

Phase 3 – Final installationWinch Floor Roof floor

Phase 3 – Final installation

Phase 3 – Final installation

Phase 3 – ImplementationWhat did the sensor see?

detection threshold of 101% was used – 1%Rule

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What was the matte level?

Phase 3 – Day 1 trial

Dip 2

Total of 12 dips conducted- repeatability and precision

Matte level variance within reasonable limits ±10mm

Levelmatte = Depthvirtual + Furnace0 - Entrymatte

Phase 3 – Day 2 Case study

Dip no Time matte level Comments

mm

09:00 250 manual sounding

14 09:05 332

15 09:13 321

16 09:46 301 Matte tap @ 9H31

17 09:48 304 Matte tap @ 10H03

11:00 240 Matte tap @ 11H03

18 12:14 283

19 12:20 283 Matte tap @ 12H38

13H00 250 manual sounding

20 13:09 260

21 13:22 254

How does the matte level varies with changes in Process conditions?

Phase 3 – Day 2 Case study

Agellis showed variances as per process changes (more sensitive)

Manual sounding measurements did not change

Measured Matte Levels

200

220

240

260

280

300

320

340

08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00

Time

Matt

e L

ev

el (m

m)

2010-10-13 Matte tap

Phase 3 – Day 3 Power off● Total of 5 dips conducted with Power off

● No effect on measurement accuracy

● Measurements were consistent with the sounding bar measurements

●●●● Agellis ELP showed variances with process changes

Phase 3 - Key learning's from trial

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Negatives●●●● Slag cracking – lance too light●●●● No build-up detection - bottom readings are unreliable●●●● Rate of descend of winch – fixed speed and thermal exposure of sensor

Positives●●●● Good matte signal●●●● Teamwork constituted to the success (Eng/Elect/Instr)●●●● Customer requirement (no effect on operations)●●●● Better understanding of matte production over time

To sum up

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●●●● The measurement results attained during the trial period were consistent, reliableand accurate●●●● The Agellis trial was deemed successful as all criteria for the trial have been met●●●● Agellis ELP – can be used as an alternative for matte level measurement

Phase 4 – R/D to Operational

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• Matte level output required for process monitoring – software acquired

Enhancements to system

More dips during training of shifts

Date time matte level comments

mm

10-Aug 15H00 240 manual sounding

16H46 232 agellis

17H00 250 manual sounding

246 agellis

17H38 tapped and slagged

12-Aug 13h00 270 manual sounding

283 agellis

13H33 matte tapped

260 agellis

270 manual sounding

16-Aug 11H00 210 manual sounding

226 agellis

slagging whole morning

Handing over to Operations - End of November 2011

Thank You!

Smelting is an ancient art but is becoming a recent science