MECHANICAL LGP REPORT NO.
3
SECONDARY SMELTING
KANSANSHI COPPER SMELTER
AUTHOR: Michael Simpasa
GLOBAL ID: 042479
MENTOR: Sydney Kapota
DATE: 27/05/2021
Table of Contents
Chapter 1 SECTION UNDERSTANDING ............................................................ 1-2
Introduction ............................................................................................................................................1-2
Pierce Smith Converters .........................................................................................................................1-2
Evaporative Cooling Chambers ..............................................................................................................1-2
Anode Furnace ........................................................................................................................................1-2
Cast Wheel ..............................................................................................................................................1-2
Main Aisle Cranes ..................................................................................................................................1-3
Chapter 2 PRACTICAL EXPERIENCE: .............................................................. 2-3
1. Changing gland packing on PSC3 bustle pipe swivel joint ............................................................2-3
2. Changing hood panels 1R and 1L ...................................................................................................2-4
3. Changing out a diesel pump on PSC3 valve rack ...........................................................................2-6
4. Task Changing tuyeres on PSC2 .....................................................................................................2-7
5. Preparing tuyere drill .......................................................................................................................2-9
7. Main Aisle Crane Main bale Inspection and PM ..........................................................................2-13
Other Involvements ...........................................................................................................................2-13
Further Key learning points...............................................................................................................2-14
Further Recommendations ................................................................................................................2-14
Maintenance strategies ......................................................................................................................2-14
Chapter 1 SECTION UNDERSTANDING
INTRODUCTION
The Secondary Smelting section is responsible for converting the matte (60-65% Cu) received from
primary smelting first into blister copper (85%Cu) in the Pierce Smith Converters and finally into anode
copper ((8.5% Cu) in the Anode furnace.
The pieces of equipment key to these processes include:
Pierce Smith Converters
There are four Pierce Smith Converters, PSCs, that convert matte to blister copper. Two are always
running, with one on standby and another on rehabilitation. The PSCs are aided in their function by
auxiliary equipment which include: tuyeres, the tuyere punch car, back flaps, holding and heat up
burners, main drive system, emergency hydraulic roll-out system.
Evaporative Cooling Chambers
The Evaporative Cooling chamber is responsible for cooling the off-gas from the converters before it is
transported to the scrubber for cleaning and further processing in the acid plant. The off-gas leaving the
converters through the primary hood door escapes into the ECC. Spray coolers at the entrance to the ECC
cool the off-gas and collect dust which falls to the bottom into tote boxes via pneumatic double flap
valves. The ECC cools the off-gas from the converters from 700°C to around 350°C aided by: water
spray lances, a spray water tank, two water pumps, double flap valves and a valve rack.
Anode Furnaces
There are two Anode Furnaces that convert blister copper from the converters into anode copper. They
have 2 tuyeres through which they receive air essential to the process. Auxiliary pieces of equipment
supporting the anode furnaces include: cooling water valve racks, charging doors, fuel valve racks,
combustion air fans, incinerators and an I.D fan
Casting Wheel
Two Anode casting wheels, each driven by two servo motor driven gears, are the final stage of copper
anode preparation. They receive molten anode copper from the furnaces. The anode copper is then cast
into solid anodes, ready for transportation. Pieces of equipment around the casting wheels include:
Casting molds, launders, bosh tanks, hydraulic pre-loosening system, sumps pumps, a cooling tower, a
hydraulic reject anode take off machine, a barium sulphate screw conveyor, mold dressing system,
exhaust fans, spray coolers, etc.
Main Aisle Cranes
There are three Main Isle Cranes that are used to move molten metal between the MSEF and the
converters, and between the converter and the anode furnaces. At any one point, two cranes are in
operation while the third is on maintenance. Each crane has a 100T main bale with two hooks and a 40T
auxiliary bale with a single hook. The main bale drum is driven by two electric motors while the auxiliary
is driven by one. Both systems have electrically actuated brakes and emergency hydraulic brakes in case
of power failure.
Chapter 2 PRACTICAL EXPERIENCE:
1. Changing gland packing on PSC3 bustle pipe swivel joint
Problem
Gland packings had worn out
Cause
Pressure of gland follower on gland seal/swivel movements/high temperatures
Implication
Air would leak, thereby reducing air pressure to the tuyeres, which would result in tuyeres being
chocked during operation
Solution
Replace gland packings
Procedure
Isolate LP Air valve
Ensure bypass valve is closed
Loosen bolts on flange follower
Remove worn out gland packing
Clean gland seat
Cut new gland packing to required length
Lubricate gland seat for easy installation
Apply copper compound to gland packing
Fit gland packing, ensuring the separation is at different points for all 4 GPs (90degrees apart)
Push in gland follower
Replace bolts
Adjust bolts till gap between flange and gland follower is 35mm
Key Learning points
Working principle of swivel joints
The swivel joint uses a special type of gland packings with thick rubber strands in the center. The
rubber was incorporated to increase the life span of the packings which wear due to friction and
heat during operation. The gap between flange and gland follower is adjusted whenever air leaks
occur.
2. Changing hood panels 1R and 1L
Problem
Hood panels were corroding on the inside
Cause
Weak acid formed by the water from sprayers cooling the SO2 from the converter
Implication
Overtime, the corroding plates would wear completely. The cooling water in the plates would
then be exposed to SO2, resulting in more weak-acid formation and corrosion of the other plates.
SO2 would the begin to escape through holes into the atmosphere.
Solution
Replace mild steel plates with Stainless steel 304 plates
Procedure
- Uninstalling
Drain cooling water
Disconnect cooling water pipes
Disconnect water spray lances
Loosen and remove all panel 7R bolts
Remove panel 7R with the aid of a chain-block to create room for moving panels 1R and 1L
Weld lugs onto panel 1R (3 inside and 1 outside)
Lower panel 1R using chain-blocks to the floor next to the PSC
Lower panel 1L using chain-blocks to the floor next to the PSC
Main Aisle Crane is used to lower it into the aisle to be picked by a fork lift
- Installing
Lift stainless steel plates 1R and 1L using Main Aisle Crane onto PSC platform
Weld lugs onto new plates
Lift panels starting with 1L using chain-blocks and hold them in position
Fix bolts and tighten
Install cooling water pipes
New plates have a different flange hole orientation; therefore, the old pipe flanges are cut, rotated
then re-welded
Install panel 7R
Install spray lances connect all other pipes
Key Learning points
Stainless steel has better corrosion resistance properties than Mild Steel and is a better fit in
corrosive environments
Type 304 stainless steel is a T 300 Series Stainless Steel austenitic. It has a minimum of 18%
chromium and 8% nickel, combined with a maximum of 0.08% carbon. It is defined as
a Chromium-Nickel austenitic alloy. It was selected for its rust and corrosion resistance and its
ability to work around temperatures of up to 870 degrees Celsius.
316 Stainless Steel (Cr 16%, Ni 10%, Mo 2%) is another steel type that would have worked
especially due to its superior corrosion resistance (it is able to resist chloride attack). However, for
this application 304 achieves the same protection at a lower cost. Hence the selection.
Recommendations
New stainless-steel plates must have flanges with similar hole orientation as existing pipes to
reduce the overall time taken to carry out this task.
3. Changing out a diesel pump on PSC3 valve rack
Problem
There was nothing wrong with the pump. However, as a Precautionary measure, the diesel pump
is always changed during converter rehab. The pump is checked and refurbished if need be.
Implication
The diesel pump not running would affect the holding and heat-up process of the converter. This
would impair the converter in a case of maintenance or shut down.
Procedure
Isolate the pump manually (close valves on rack)
Drain the pump by opening a valve
Disconnect inlet and outlet pipes
Undo pump holding down bolts
Decouple pump and motor
Remove pump
Place new pump
Couple pump and motor
Connect pipes
Tighten holding down bolts
Energize pump
Key Learning points
Holding burner and Heat-up burner functions and fuel/air feed system
The holding burner helps keep the converters at temperatures above 800 degrees. This is done to
maintain the integrity of the refractory lining as well as save on time that would be used on burner
heat-up if the PSC was allowed to cool down frequently.
4. Task Changing tuyeres on PSC2
Problem
Tuyere failed at pipe collar
Cause
Shock from punching during operation on a weak weld
Implication
Air would leak through crack, causing a drop in air pressure during tuyere blow. This would
cause molten metal to flow back into tuyere, damaging the tuyere assembly and resulting in an
inefficient converting process.
Procedure
Obtain permit
Isolate convertor
Weld lug on the cover plates
Remove tuyere cover plate
Remove angle iron holding tuyere block
Detach tuyere flexible hose
Remove Y clamp
Remove tuyere block
Remove damaged tuyere pipe
Install new tuyere pipe
Install tuyere block
Install Y clamp
Install Angle iron holding tuyere block
Attach tuyere flexible hose
Install cover plates
Key Learning points
Tuyere block assembly and operation
Safety during tuyere installations is key due to hot environment and the gap between the PSC and
the platform
Recommendations
Engage supplier to request reinforcement of weld, otherwise change supplier of tuyere pipes
5. Preparing tuyere drill
After changing the refractory lining in the converter, the tuyere drill is used to drill holes in which
the tuyere pipe will be inserted. The hydraulic tuyere drill had to prepared for this.
5.1 Changing drill machine’s rotary motion hydraulic motor
Motor was faulty- rotated at lower speed than other rotary motor.
The Initial plan was to change motor
However, it was observed that the rotary and axial feed motors were of different sizes
Motors were then swapped.
After swapping, the motor performed as expected.
Minor oil leaks were observed on two of the four motors during the test
Recommendation
The pumps must be refurbished to prevent any further loss of hydraulic oil.
5.2 Testing of tuyere drill
Task
Hydraulic system to be tested in preparation for tuyere hole drilling
Procedure
Check hydraulic system for any visible faults
Check hydraulic control panel
Connect pipes to hydraulic motors
Connect pipes to control panel
Connect electric motor to power source
Release Emergency stop on control panel
Power hydraulic system
Test rotational movement
Test feed movement
Results
The motors were able to rotate simultaneously and at similar speeds
2 out of 4 motors were leaking through cracks
Recommendations
Attend to all 4 motors; check them thoroughly and refurbish/replace them before the next drilling
job.
6. Ladle Inspection and thickness testing
Inspections are carried out on ladles regularly to track wear on the ladles. The data collected helps
in planning for maintenance and ensure availability of the said equipment.
If ladles are not inspected regularly, it would be hard to detect failure that occurs as a result of
operation such as wear and cracking. Failure during operation (molten metal leaks) would be
catastrophic to all surrounding personnel and equipment.
Procedure
Obtain safe working permit
Risk Assessment
Prepare ultrasonic thickness tester
Clean testing points
Apply grease to tester probe
Switch on the machine
Adjust to suitable settings
Place probe on cleaned points on ladle
Record the thickness reading
Take other measurements around the ladle as specified on the checklist
Key Learning points
Ladles wear criteria and rehabilitation
Recommendations
Ladle chains to be inspected more regularly using NDT
Construct a concrete flat floor in main aisle for ladle dimensions’ measurement as current method
is inaccurate due to uneven floor.
7. Main Aisle Crane Main bale Inspection and PM
Problem
Rivet was partially broken
Main bale hook plates began separating
Width deviated from 100mm initial to 140mm
Cause
Constant heating and cooling from normal operation
Implication
Cracks would propagate and finally cause the hook to separate into individual hooks
Procedure
Obtain permit
Clean hook – remove metal buildup with scraper
Clean with grinder
Weld using electrodes till both gaps are filled
Grind further to clean weld
Tuck rivet using electrode welding – to prevent it from falling out
Other Involvements
Removing pneumatic cylinder from tuyere punch car
Tuyere alignment
Tuyere pressure testing
Preventative maintenance (PM) of Cast wheel steam exhaust fan
PM of Main Isle Cranes
PM of Anode Furnace 1 draw bridge winches
Crane trans-positioning
PM and inspection of cooling water feed pump 4108
PM and inspection of Hood winches for PSCs 1 and 2
PM and inspection of PSC4 main drive
PM and inspection of Fan FA4501
Hydraulic system familiarization
Aisle crane Main Bale rope inspection
Changing oil rings on retractable vibrating feeder pneumatic cylinder
Exhaust Fan4302 Pm and inspection
Inspections on Sump pit pumps
Further learning points
Developed an understanding of hydraulic systems, their symbolism, how to interpret hydraulic
circuits and the role they play in the secondary section.
Further Recommendations
Train personnel in hydraulic systems
Procure infrared thermometers for fitters- they have not been recording bearing and gearbox
temperatures during PMs
Maintenance strategies
The Secondary smelting section employ 3 types of maintenance: Preventative, Corrective and
Predictive. The type of maintenance deployed on any piece of equipment is dependent on the type of
equipment, its operation and the required availability of the equipment.
Preventative maintenance and visual inspections are practiced daily on different pieces of equipment
that are usually available e.g. pumps, fans, conveyors. Corrective maintenance is employed on units that
are usually running e.g. converters.
