	The following article appears in the journal JOM, 52 (2) (2000), pp. 22-28.

Prebake Cell Technology: A Global Review

Alton Tabereaux

TABLE OF CONTENTS
INTRODUCTION ALCAN ALUMINUM ALCOA UNIVERSAL PREBAKE CELL NOMENCLATURE ALUSUISSE ALUMINUM COMALCO AND DUBAL HYDRO ALUMINUM KAISER ALUMINUM ALUMINUM PECHINEY REYNOLDS METALS VAW ALUMINUM OTHER WESTERN PREBAKE TECHNOLOGIES RUSSIA CHINA CONCLUSIONS ACKNOWLEDGMENTS


Figure 1. Pechiney AP-30 300 kA "super pot" PB cell technology

There are currently more than 50 different types of PB cell technologies being used in the aluminum industry. This article reviews the current status of prebake cell technology worldwide with a look at some of the leading aluminum producers and their technologies. The nomenclature for prebake cells is also discussed.

INTRODUCTION

Aluminum companies are operating more than 50 different types of prebake (PB) cell technologies at smelters worldwide. Seventeen additional types of prebake cells are currently operating in Russia and China.

Over the years, significant improvements and changes in the operation of PB cells have occurred. Potline amperages have increased 500% from the 1940 vintage 50 kA cells to the current 300 kA super pots (Figure 1). Correspondingly, the total carbon anode area in PB cells has increased with the use of larger anodes from 5 m² to 38 m². The operational performance of modern PB cells has dramatically improved to 95–96% current efficiency, 13.5 DC kWh/kg and 1.1 work hours per tonne aluminum. Other significant changes in the design and operation of PB cells include

Improved busbar designs (including magnetic compensation of older PB cells) to reduce magnetohydrodynamic effects

Point break and feed of alumina
Computer process control systems and improved alumina and voltage control algorithms
Multipurpose cranes for tapping, changing anodes, etc.
Low-ratio (high-excess AlF₃) bath chemistry
Improved cell hooding and alumina dry-fume treatment systems
Air slides and dense phase systems for the delivery of alumina to cells Improved anode quality
Improved cathode designs with fully graphitized cathode blocks and SiC sidewall lining
Automatic feeding of AlF₃
Mechanization of all aspects of smelter operations

ALCAN ALUMINUM

Alcan Aluminium developed three versions of end-to-end, side-work PB cell technologies that are still in use at various smelters and one side-by-side, point-feed PB cell that is no longer in operation (Table I).

There are five potlines of 70 kA end-to-end, side-work PB cells at the Arvida plant (situated in Jonquière, formerly known as Arvida). The first generation of cells was started in 1940–1941 at 45 kA and were upgraded to 65 kA from 1963 to 1969 and then to 70 kA.

Two potlines of 160 kA end-to-end, side-work PB cells are used at Lynemouth (line one started up in 1972, line two in 1973). Original amperage was 140 kA). Both have been converted from side-work to point-feed technology.

Three potlines of end-to-end, side-work PB cells are operational at Kurri Kurri (line one started up in 1969 at 148 kA, line two in 1979 at 160 kA, and line three in 1985 at 175 kA). Potlines two and three at Kurri Kurri have been converted from side-work to center-work and point-feed technology.

Alcan developed and operated five experimental side-by-side, point-feed PB cells at Jonquière from 1981–1992. The busbar design had four side risers, four cathode busbars below the cells, and two around the ends. The first generation of cells, Apex and A-275, operated at 280 kA. The last generation of cells, A-310, operated at 310 kA. Most of these had individual anode drives and computer control adapted to this feature.

Table I. Global Prebake Cell Technology

Company/Cell

UPBN Name

kA

Riser Design

Number of
Alumina Feed

Anodes

Smelters

Alcan

Arvida Prebake

AC-7-EE

70

End-to-end
(Pos. end feed)

SW

18

Jonquière

Lynemouth^A

AC-16-EE-M1

160

End-to-end

PF

22

Lynemouth

KK-1
and KK-2^A

AC-16-EE-M2

160

End-to-end

CW

22

Kurri Kurri

KK-3^A

AC-17-EE-M3

175

End-to-end

PF

22

Kurri Kurri

Apex, A-275^A
and A-310

AC-28
and AC-31

280
& 310

Side-by-side
four side risers

PF

24

Arvida R&D Center^B

Alcoa

N-40 (Niagara)

AA-4

40-80

Side-by-side

CW and PF

24

Mead, Troutdale

AA-4-SE

End riser and
Side risers

24 and 26

Renukoot,
Vancouver 28

P-88

AA-10-SE3

100

Side-by-side
end risers

PF

24

Warrick

T-51

AA-10-SE1

100

Side-by-side
end risers

CW and PF

20

Rockdale,
Wenatchee

P-75

AA-10-SE2

100

Side-by-side
end risers

CW and PF

20

Massena^B

P-100

AA-10

125-130

Side-by-side
two side risers

PF

26

Rockdale, Warrick,
Wenatchee

P-155

AA-16

155-180

Side-by-side
two side risers

PF

24

Badin, Grande Baie,
Laterrière,
Pt. Henry, Sebree

A-697

AA-18

180

Side-by-side
two side risers

PF

24

Mt. Holly, New Madrid,
São Luis

P-225

AA-23

225

Side-by-side
four side risers

PF

32

Massena,
Tennessee

A-817

AA-30

275-300

Side-by-side
five side risers

PF

40

Portland

Alusuisse

EPT-10

AS-8-SE

80-130

Side-by-side
end risers

PF

22

New Johnsville,^D
Salzburger^D

EPT-10

AS-8-EE-M1

80-130

End-to-end

PF

24

Steg, Delfzijl,
Straumsvík
(Potroom 1 and 2)

EPT-10^C

AS-8-EE-M2

80-150

End-to-end

PF

24

Husnes

EPT-10^C

AS-8-EE-M3

80-130

End-to-end

PF

24

Straumsvík
(Potroom3)

EPT-14

AS-14-EE-M1

140-145

End-to-end

PF

26

Essen
(Potrooms 1 and 2),
Lake Charles,^D
Sibenik^D

EPT-14^C

AS-14-EE-M2

140-170

End-to-end

PF

26

Essen
(Potroom 3)

EPT-14

AS-15-EE

145-170

End-to-end

PF

26

Hillside

EPT-18

AS-18

180-190

Side-by-side
side risers

PF

32

Rheinfelden^D

Comalco and Dubal

CD-200

CD-20

190-206

Side-by-side
side risers

PF

20

Dubai, Tiwai Point

Hydro

HAL-150^C

HAL-15-EE-M

160-175

End-to-end

PF

20,22

Årdal,
Sunndalsøra

HAL-230

HAS-23

230

Side-by-side
four side risers

PF

26, 30

Høyanger,
Venalum (line 5),
Ziar

HAL-250

HAL-25

250

Side-by-side
four side risers

PF

30

Årdal

Kaiser

P-93

KA-6-EE

60

End-to-end

PF

6

Tacoma,
Nadvoitsy

P-57^E

KA-9-SE

93

Side-by-side
end risers

CW and PF

20

Bell Bay,
Ravenswood

P-69

KA-14-SE

140-175

Side-by-side
end risers

CW and PF

18

Hollyhead, Dubai,
Tema, Hawsville,
New Madrid,
Tiawai Point, Voerde

P-86

KA-15

150

Side-by-side
side risers

PF

16

Sundsvall

P-80

KA-18

180-190

Side-by-side
side risers

PF

16

Chalmette,^D Tacoma^D

Pechiney

AP-7

AP-70-SE

70

Side-by-side
end risers

SW
(Lines A and B = PF)

12

St. Nicolas

AP-9

AP-9-SE

90

Side-by-side
end risers

SW
(Line C = PF)

16

Auzat, Mostar,^F
Slatina,
St. Nicolas

AP-LN

AP-9-EM

90

End-to-end
end riser and
two side risers

SW

20

Lannemenzan

AP-CM

AP-13-EEM

125

End-to-end
end riser and
two side riser

SW

24

Edéa

AP-13

AP-13-SE

130

Side-by-side
end risers

SW

18

Belem, Frederick,
Ferndale,
Vlissingen

AP-14

AP-14-SE

140

Side-by-side
end risers

SW

20

Mostar, San Ciprian

AP-18

AP-18-16

180

Side-by-side
four side risers

PF

16

Baie Comeau, Bécancour,
Ft. William, Karmøy,
Kidricevo, Orissa

AP-18-18

18 (Aluar)
smaller anodes

St. Jean-de-Maurienne
(F Line), Tomago,
Puerto Madrym

AP-30

AP-30-20

300

Side-by-side
five side risers

PF

20 (double)

Bahrain, Dunkirk,
Sept-Iles, Hillside

40 (single)

Boyne, Deschambault,
St. Jean-de-Maurinne
(G Line)

Reynolds

P-6^G

RY-8-SE

75

Side-by-side
end risers

CW

28

Alcasa, Arak,
Troutdale

Invergordan

RY-14-SE

130

Side-by-side
end risers

CW

18

Invergordon^H

P-19^G

RY-16-SE

145-165

Side-by-side
end risers

CW and PF

18

Hamburg, Venalum,
Alcasa, Santa Cruz

P-19S^G

RY-16

160-170

Side-by-side
side risers

PF

18

Alcasa, Hamburg

P-20S^G

RY-17

170

Side-by-side
side risers

PF

18

Alcasa, Ikot Abasi

P-23S^G

RY-18

180

Side-by-side
side risers

PF

18

Alcasa

VAW

Erftwerk

VAW-11-EE

110-126

End-to-end

SW

Continuous

Stade

CA-120

VAW-12-EE

120

End-to-end

PF

14

Danjiangkou

CA-165^C

VAW-17-EE-M

165-170

End-to-end

PF

20

Bayside, Rheinwerk

CA-180

VAW-18

180

Side-by-side
side risers

PF

20

Grundartangi

CA-240

VAW-24

240

Side-by-side
side risers

PF

24

Töging^B

CA-300

VAW-30

300

Side-by-side
side risers

PF

32

Sayansk^B

Montecatini

P-115

MS-12-EE

115-125

End-to-end

SW and PF

16

Bahrain

P-155

MS-16-EE

155-165

End-to-end

SW, CW,
and PF

16

Fusina, Puerto Madryn,
Porto Vesme

Elkem

P-155

EK-16

155

End-to-end

SW and PF

18

Mosjøen

Sumitomo

S-170^C

SM-17-SE

185-00

Side-by-side
end risers

CW and PF

18

Boyne Island,
Kula Tanjung

Egyptalum

P-200^C

EG-20-EE-M

200

End-to-end

PF

24

Nag Hammadi

Venalum

V-350

VN-35

320

Side-by-side
four side risers

PF

36

Puerto Ordaz

Russia

C-50

RU-5-EE

50

End-to-end

PF

26

Volkhov

C-125M^C

RU-13-EE-M

125

End-to-end

PF

14

Krasnoyarsk (Line 8)

C-160^C

RU-16-EE

155-165

End-to-end

PF

22

Krasnoyarsk (Line 7),
Tadzhik,
Kamensk-Uralsky

C-175M2^C

RU-18-M2

175

End-to-end

PF

24

Sayansk, Tadzhik

C-190^C

RU-19-EE

180

End-to-end

PF

26

Sayansk

C-255

RU-26

255

Side-to-side
side risers

PF

36

Tajik, Sayansk,
Volgograd
(four pots)

C-255M1

RU-26-M1

C-255M2

RU-26-M2

C-300

RU-30

300

Side-by-side
four side risers

PF

32

Sayansk^B

China

P-60

CH-6-EE

60-75

End-to-end

SW, PF

10-12

^_I

P-75

CH-8

75

Side-by-side
one qt. riser

SW

10

Zhengzhoou

P-115

CH-12-EE

115

End-to-end

PF

14

Danjiang^J

P-140

CH-14-SE

135-140

Side-by-side
end risers

PF

20

Baotou, Fushun,
Qinyang

P-155

CH-15-SE

150

Side-by-side
end risers

CW (PF)

26

Baiyin^K

P-160

CH-16-SE-M

160

Side-by-side
end risers

PF

24

Guizhou^L

P-160

CH-16

160-180

Side-by-side
side risers

PF

24

Pingguo, Qinghai,^M
Xinan

P-200

CH-20

185-200

Side-by-side
side risers

PF

28

Guizhou,
Kunming

P-280

CH-28

280

Side-by-side
side risers

PF

40

Qingyang

P-320

CH-32

320

Side-by-side
side six risers

PF

48 (20)

Pingguo

SW--side work, CW--center work, PF--point feed.
A Magnetic compensation, asymmetric busbars.
B Cells not in operation.
C Magnetic Compensation.
D. Smelter closed.
E Assigned by the author.
F Partially restarted.
G Total anode area (square meters).
H Smelter shutdown.
I Prebake cells are in the test stage at more than ten smelters for retrofitting Söderberg cells.
J Smelter is from VAW Töging, Germany.
K Smelter is from Japan.
L Nippon Light Metals prebake technology.
M Magnetic compensated.

ALCOA

Alcoa has developed nine different types of PB cell technologies with increasing amperage that are currently used in aluminum smelters: side-by-side, end-riser PB cells N-40, T-51, P-75, and P-88 and side-by-side, side-riser PB cells P-100, P-155, A-697, P-225, and A-817.

In the 1940s, Alcoa built seven aluminum smelters for the U.S. government using the Alcoa N-40 (Niagara) 50 kA end-riser, center-work PB cell technology, reported to have first been developed at the Niagara Falls plant. The smelters at Brooklyn, New York; Massena, New York; and Riverside, California, were shut down. Other aluminum companies eventually acquired Mead (Kaiser), Jones Mills and Troutdale (Reynolds), and Vancouver (Vanalco). All but Jones Mills continue to operate today with upgraded, modernized versions of the original Alcoa PB technology. Similar Mead-type PB technology was used by Hindalco to build potlines at Renukoot, India, in 1974, making significant retrofit modernization improvements in the original PB cell technology.

In the 1950s, Alcoa built potlines of the T-51 end-riser design at Rockdale and Wenatchee. An enlarged version, the P-75, was installed at Massena (it has since been decommissioned) and another version, the P-88, was installed at Warrick. In the early 1960s, the first quarter-riser design, the P-100, was installed in potlines at Rockdale, Wenatchee, and Warrick.

Figure 2. Alcoa P-155 PB cells at Latterrière, Canada.

Five aluminum smelters are now operating with the Alcoa P-155 170 kA two side-riser, point-feed PB cell technology introduced in 1969, including Badin, Grande Baie, Laterrière, Pt. Henry, and Sebree (Figure 2). Three smelters operate with the Alcoa A-697 180 kA (2) side-riser, point-feed PB cell developed in 1977—Mt. Holly, New Madrid (Noranda), and São Luis.

Alcoa has operated two smelters with the Alcoa P-225 225 kA four side-riser, point-feeder cell at Tennessee since 1970–1972 and at Massena since 1975. The P-225 cells have the capability of controlling individual anode movements with two anodes per anode jack/motor drive. Alcoa also developed the A-817 300 kA five side-riser point-feeder PB cell technology that operates at the Portland smelter in Australia.

The oldest continuous operating aluminum smelter in the United States is the Alcoa Massena smelter, where the first ingot was cast in 1903. The Badin smelter was purchased from Pechiney while still under construction in 1919.

ALUSUISSE ALUMINUM

Alusuisse Aluminium has developed eight types of PB cell technologies; six are still in operation at aluminum smelters. End-to-end PB cells include three variations of EPT-10 and three variations of EPT-14. Side-riser PB cells are EPT-10 and EPT-18. The EPT prefix for Alusuisse PB cells stands for elektrolysezelle mit vorgebrannten anoden (electrolysis pot with PB anodes), prozessgesteuerter (computer control), and tonerdezusatz (alumina feed).

Figure 3. Alusuisse EPT-10 end-to-end PB cells at Straumsvik, Iceland.

Figure 4. A Comalco-Dubal CD-200 PB cell at Tiwai Point, New Zealand.

Alusuisse built the EPT-10 end-to-end PB cells at Delfzijl, Husnes (Søral), New Johnsville (closed), Salzburger (closed), Steg, and Straumsvík (Isal) (Figure 3). Potlines were built using the EPT-14 end-to-end PB cells at Essen, Lake Charles (closed 1986), Sibenik (closed 1992), and Richards Bay, Hillside (Alusaf). The potlines have an asymmetric magnetically compensating busbar design to increase the electromagnetic stability of the pots, making it possible to dramatically increase the current intensity without a loss in current efficiency. Søral, for instance, has increased the current of ten test pots from 120 kA to 150 kA, resulting in the decision to convert the busbar system of all 320 pots at the plant by December 1999. The EPT-18 side-by-side, point-feed PB cells at Rheinfelden are no longer operating as the smelter was closed in 1991.

COMALCO AND DUBAL

The CD-200 is one of the most recently developed PB cell technologies in the aluminum industry. Comalco and Dubal jointly developed the CD-200 200 kA side-riser, point-feed PB cell with 20 anodes. Dubal now refers to its cell as the CD-20 (20 anodes), as their cells are operated at an amperage higher than 200 kA. Two potlines (485 cells) of the CD-200 cells are in operation at Dubai, and a short potline (48 cells) of CD-200 cells is in operation at Tiwai Point (Figure 4). A higher amperage PB cell is being developed and evaluated in the developmental potroom at Dubai.

Dubal has made significant retrofit upgrades to the original 499 Kaiser P-69 cells that were initially designed to operate at 140 kA (150 kA maximum). The cell is now referred to as D-18 (18 anodes) PB cells operate at approximately 180 kA. A few D-18 cells are in operation at Almahdi.

HYDRO ALUMINUM

Figure 5. A Hydro Aluminium HAL-230 kA PB cell at Ziar, Slovalco.

Hydro Aluminium has developed two types of PB cell technologies: end-to-end PB cell HAL-150 and side-riser PB cell HAL-230.

The 150 kA end-to-end (originally side-work) PB cells at Årdal and Sunndalsøra have been converted to point feeding. The busbar system has been retrofitted with compensating bus to reduce the high B_z fields associated with the closeness of the adjacent row of pots in the same potroom. Four 250 kA cells are in operation in Årdal and are a further development of the HAL-2130 kA cells. Hydro Aluminium developed the HAL-230 230 kA four side-riser, point-feed PB cell at Høyanger, and built a potline at the aluminum smelters at Puerto Ordaz (Venalum) in 1988 and Ziar (Slovalco) in 1995 (Figure 5).

KAISER ALUMINUM

Kaiser Aluminum developed five different types of PB cells: side-by-side, end-riser PB cells P-57, P-69, and P-90 and side-by-side, side-riser PB cells P-80 and P-86. Kaiser named their PB cells for the year in which they were developed: P-57 (1957), P-69 (1969), P-80 (1980), P-86 (1986), and P-90 (1990).

Four cells are still in operation. The Kaiser P-57 90 kA PB cell is operated at both Ravenswood (Century) and Bell Bay (Comalco) smelters. The Kaiser P-69 150 kA end-riser, center-work PB cell was one of the first international PB cells, used in seven aluminum smelters at Hollyhead (Anglesey), Dubai (Dubal), Voerde (Hoogovens), Hawesville (National Southwire), New Madrid (Noranda), Tiwai Point (Comalco), and Tema (Valco). Many smelters have converted from center work to a modified point feeder.

A potline of 60 kA Söderberg cells at Sundsvall (Kubal, formerly Gränges), was converted in 1987 to 56 Kaiser P-86 150 kA side-riser, point-feed PB cells. More than 30 HS Söderberg cells at Nadvoitsy, Russia, have been converted to the Kaiser K-93 60 kA end-to-end, point-feed PB cell with six anodes, developed at Tacoma and Chalmette (closed). These cells had magnetic compensation to reduce the B_z fields due to the closeness of the adjacent row of pots in the same potroom.

Kaiser developed and operated six P-80 195 kA (4) side-riser, point-feed PB cells with 16 anodes at Tacoma in 1981. These are no longer in operation.

ALUMINIUM PECHINEY

Aluminium Pechiney has developed eight types of PB cell technologies, from 70 kA to 300 kA, that are operating at aluminum smelters today: end-to-end, side-riser PB cells AP-LN and AP-CM; side-by-side, end-riser PB cells AP-7, AP-9, AP-13, and AP-14; and side-by-side, side-riser PB cells AP-18 and AP-30. In the cell naming scheme, AP is Aluminium Pechiney, and the potline amperage in kA is shortened by a factor of ten (e.g., AP-13 designates 130 kA). Pechiney has constructed the largest number of smelters (16) to date using its AP-18 and AP-30 PB cell technology.

The end-to-end VS Söderberg cells (AP-LN) at Lannemezan, France, in 1970 and Alucam (AP-CM) at Edéa, Cameroon, in 1978 were retrofitted to PB cells with central side-riser bus to provide magnetic compensation for the adjacent row of pots in the same potroom for improved cell performance. The AP-7 and AP-9 PB cells (ADG) at St. Nicolas, Greece, were retrofitted from side work to point feed in 1986. The AP-13 side-by-side, end-riser cells were built at Belem (Albras), Ferndale (Intalco), Frederick (Eastalco), and Vlissingen (PNL). The AP-13 cells at Ferndale (Intalco) were retrofitted in 1991 with magnetically compensated busbars to reduce the high B_z associated with the high current flow around the ends of the cell.

Figure 6. A Pechiney 300 kA PB cell at St. Jean-de-Maurienne, France.

Since the 60 cells were installed at St. Jean-de-Maurienne in 1979 (Figure 6), nine aluminum smelters (3,172 cells) have been built using Pechiney AP-18 180 kA four side-riser, point-feed PB cell technology. These smelters include Bécancour (ABI), Baie Comeau (Reynolds), Ft. William (BA), Karmoy (Hydro Aluminium), Kidricevo (Talum), Orissa (Nalco), St. Jean-de-Maurienne-F Line and Tomago (Pechiney), and Puerto Madryn (Aluar, started in 1999). Pechiney recently reengineered its AP-18 PB cell with improvements to the lining design, anode and pin dimensions, and sidewall ventilation to create an AP-21 cell that can operate at 210 kA.

The AP-30 300 kA five side-riser, point-feed PB cell technology was developed at St. Jean-de-Maurienne, starting in 1981. Seven aluminum smelters (2,040 cells) have been built using Pechiney AP-30 cells, and two more smelters (720 cells) are under construction. The AP-30 smelters include Bahrain (Alba), Alma (Alcan, under construction), Septlles (Alouette), Richards Bay-Hillside (Alusaf), Boyne Island (Comalco), Dunkirk, Deschambault (Lauralco), Mozal (under construction), and St. Jean-de-Maurienne G-Line. Four of the AP-30 smelters have 20 pairs of anodes (two anodes per stem), and three AP-30 smelters have 40 individual anodes per cell. With improvements made to the cell lining, it has been reported that the amperage has been increased in the AP-30 PB cells at several smelters to 325 kA.

The oldest Pechiney aluminum smelter in operation is at St. Jean-de-Maurienne, which started up in 1907; the start-up of the Auzat smelter was in 1914.

REYNOLDS METALS

Figure 7. Reynolds P20S PB cells at ALSCON, Ikot, Nigeria.

Reynolds Metals developed five types of PB cells; four types are still in operation. Uniquely, the P-# refers to the number of square meters of anode area. The developed cells are side-by-side, end-riser PB cells P-6, Invergordon, and P-19 and side-by-side, side-riser PB cells P-19S and P-20S.

In 1972, Reynolds developed the P-6 75 kA end-riser, center-work PB cell with 28 anodes, which is operated at Alcasa lines one and two, Arak (Iralco), and Troutdale line five. In the late 1960s, Reynolds developed the Invergordon 130 kA and the P-19 145 kA end-riser, center-work PB cell at its experimental potline at the Listerhill smelter. Smelters operating with the P-19 cell include Puerto Ordaz (Alcasa), Hamburg (HAW), Santa Cruz (Valesul), and Puerto Ordaz (Venalum). Venalum has installed magnetic compensation in the P-19 end-riser cells. HAW, together with its owners VAW, Reynolds and AMAG, converted one potline at Hamburg to a P-20S 170 kA side-riser, point-feed PB cell. Reynolds developed the P-20S 170 kA side-riser, point-feed PB cell operated at Puerto Ordaz (Alcasa) and Ikot Abasi (ALSCON) (Figure 7) and the P-23S cell 180 kA side-riser, point-feed PB cell (test group) operated at Alcasa.

VAW ALUMINIUM

VAW Aluminium has developed five PB cell technologies that are in operation at smelters: end-to-end PB cells Erftwerk, CA-120, and CA-165 and side-by-side, side-riser PB cells CA180 and CA-240.

he original VAW cells at Rheinwerk were based on the Erftwerk design with continuous PB anodes. All cells at the Reinwerk smelter have been converted to PFPB with compensating three-riser asymmetric bus to reduce the high B_z fields associated with the closeness of the adjacent row of pots in the same potroom. In addition, VAW actively participates in the modernization and conversion of older cell technologies, such as the conversion of 12 Söderberg cells to 165 kA end-to-end, side-riser, point-feed PB cells at Bayside (Alusaf).

The Nordurál smelter at Grundartangi was built in 1998 using VAW CA-180 side-by-side, point-feed PB cell technology from Töging. Significant parts of the potline were purchased from the VAW Töging plant, which was taken out of operation in 1994. Similarly, potline one at Töging (100 cells, CA-120, 100 kA, end-to-end, center-work PB cells with 14 anodes) was purchased and relocated at the Danjiangkou smelter in China in 1999. An improved version of the CA-180 has been recently developed with a modified shell, lining, and superstructure as well as fully graphitized cathode blocks to allow it to operate at 210 kA.

VAW participated in the joint development and construction of six CA-300, 300 kA, side-by-side, four side-riser, point-feed PB cells with 32 anodes at the Sayansk Aluminum Smelter. These test pots are no longer in operation.

UNIVERSAL PREBAKE CELL NOMENCLATURE

Currently, there is no universal system for the nomenclature and identification of prebake (PB) cell technologies. Aluminum companies use their own naming systems, which differ widely throughout the industry. Thus, the adoption of an acceptable universal prebake nomenclature (UPBN) system is recommended for the naming of future PB cells. Without the adoption of a UPBN system, the names of prebake cells will become even more confused in the future in view of recent mergers by aluminum companies and the renaming of existing PB cells as they are modernized.

Whenever possible, the UPBN name should be as brief as possible in describing PB cells. For example, the side-by-side, side-riser PB is the most common type of cell and does not require any special notation; the amperage is shortened by dividing the kA by ten. Thus, Pot or Company Prefix – Amperage (kA)/10 (e.g., AP-18 identifies the cell as a Pechiney Aluminium, 180 kA PB cell).

UPBN PB cell nomenclature:

Use a company identification prefix (two letters or more) rather than “P” for Pot.

Starting potline amperage (kA) is divided by ten; fractions are rounded to the nearest 10 kA.

Use “EE” for end-to-end cells; no symbol is required for side-by-side PB cells.

Use “SE” for side-by-side, end-riser cells; no symbol is required for side-riser PB cells.

Use the number of anodes only when a different number of anodes are used in the same cell design (e.g., AP-30-20 and AP-30-40).

Use “M” for magnetic compensation of the busbar system.

Use “1, 2, 3 . . .” for different upgraded versions of the same cell design.

Using these guidelines, the Kaiser P-69, becomes KA-15-SE (Kaiser, 150 kA, side-by-side, end-riser PB cell) and the Alcoa A-697, becomes AA-18 (Alcoa, 180 kA, side-by-side, side-riser PB cell).

OTHER WESTERN PREBAKE TECHNOLOGIES

Nippon Light Metals developed P-160 160 kA, side-by-side, end-riser, PB cell technologies that are used in aluminum smelters in China.

Montecatini developed P-115 and P-155 end-to-end, side-work PB cell technologies that are in operation at four aluminum smelters: Bahrain (Alba); Fusina; Puerto Madryn, Argentina (Aluar); and Porto Vesme, Sardinia. Most of the potlines have been converted to point-feed technology. Several smelters have been retrofitted with compensating bus to reduce the high B_z fields associated with the closeness of the adjacent row of pots in the same potroom.

Elkem and Alcoa converted one potline of VS Söderberg cells to a 155 kA PB cell at Mosjøen.

Sumitomo Aluminium Smelting developed S-170 side-by-side, end-riser, PB cell technology that is used at two smelters at Boyne Island (Comalco) and Kula Tanjung (Inalum). Retrofit improvements made at the Boyne Island smelter include the use of longer anodes, a new sidewall and cathode design, point feed, an improved control system, and increased amperage (200 kA).

The Aluminum Company of Egypt (Egyptalum) at Nag Hammadi developed a 200 kA end-to-end PB cell with asymmetric bus and side-riser magnetic compensation to replace the VS Söderberg cells. More than 90 PB cells have been retrofitted and are in operation at the smelter.

Venalum at Puerto Ordaz, Venezuela, developed five experimental V-350 side-by-side, four side-riser, point-feed PB cells with 36 anodes that are operated at 320 kA in its developmental potline.

RUSSIA

There are 14 aluminum smelters in the former Soviet Union, the majority of which use Söderberg cells. There are six different types of PB cell technologies in Russia: end-to-end PB cells C-50, C-125, C-160, C-175M2, and C–190 and side-by-side, side-riser PB cell C-255. Most PB and Söderberg cells were designed and developed by the VAMI Institute at St. Petersburg. The letter “C” is used as a prefix for Russian PB cells (C-125 and C-160) and Söderberg cells (C-2 and C-3).

The bus system of the end-to-end C-125, C-160, C-175M2, and C-190 PB cells has been retrofitted with central-quarter riser and/or asymmetric compensating bus to reduce the high B_z fields due to the closeness of the adjacent row of cells in the same potroom.

The C-255, 255 kA side-by-side, side-riser, point-feed PB cell was developed by VAMI in the late 1970s; they were prototyped at Volgograd in four developmental cells, then built in Tadjik lines five and six. The C255M1, an upgraded version of the C-255 cell, was built in Sayansk in line three.

Five developmental CA-300 300 kA side-by-side, side-riser, point-feed PB cells were developed and operated at Sayansk in agreement with VAW. These test cells are no longer in operation.

CHINA

There are reported to be more than 100 aluminum smelters in China, but the majority of the smelters are small and use Söderberg cell technology. There are ten different PB cell technologies used in the aluminum smelters in China: end-to-end PB cell P-60; end-to-end, quarter-riser PB cell P-115; side-by-side, end-riser PB cells P-140, P-155, P-160, and P-160M; and side-by-side, side-riser PB cells P-75, P-200, P-280, and P-320. In China, it is common to use the amperage number for PB cells, such as 160 kA cell and 280 kA cell. In order to identify different PB cell technologies for the same current, sometimes the plant name is used before the amperage, such as Pingguo 160 kA cell and Qinghai 160 kA.

The P-60 end-to-end, side-work PB cells are in the test stage at more than ten smelters for retrofitting the less efficient Söderberg cells. The bus system of the side-by-side, end-riser P-160 PB cell has been retrofitted with compensating bus to reduce the high B_z fields and resulting detrimental impact on the metal pad due to the high amperage in the bus at the ends of the cells.

Two PB smelters; Danjiang P-115 end-to-end, point-feed cells; and Baiyin P-155 side-by-side, end-riser cells were transported to China from other countries. The Guizhou P-160 side-by-side, end-riser point-feed cells are Nippon Light Metals PB technology.

China is developing its own technology for retrofit improvements and the construction of future smelters. A potline (30 cells) of the P320 side-by-side, six side-riser, point-feed PB cells was put into operation at Pingguo in 1999.

CONCLUSIONS

Future PB cells will continue to become larger and operate at even higher amperages; testing has already begun at 400 kA, which is projected to be the next PB cell performance. However, larger PB cells have limitations. Some of the technical problems that will need to be addressed are

Faster deterioration of the cathode lining due to magnetics and heat balance constraints.
Potentially higher air emissions from large capacity smelters.
Increased instabilities associated with large anodes.
Higher magnetic fields.
Increased impact of cell down-time for normal cathode repair, etc. on plant production.

ACKNOWLEDGEMENTS

The author gratefully acknowledges and thanks colleagues in the aluminum industry for their contributions in the article: Yousuf Alfarsi of Dubal, Geoff Bearne of Comalco, Peter Entner of Alusuisse, Yiren Gan of China, Erik Jensen and Mikhail Khatskel of Reynolds, Vinko Potocnik of Alcan, Roger Johnson of Kaiser, Halvor Kvande of Hydro Aluminium, Michel Reverdy of Pechiney, Martin Segatz of VAW, and Barry Wheeless of Alcoa.

Alton Tabereaux is a department manager of Extractive Metallurgy at Smelter Technology Laboratory, Reynolds Metals.

For more information, contact A. Tabereaux, Reynolds Metals, Smelter Technology, 4276 Second Street, Muscle Shoals, Alabama 35661.

Copyright held by The Minerals, Metals & Materials Society, 2000

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Table I. Global Prebake Cell Technology
Company/Cell	UPBN Name	kA	Riser Design	Number of Alumina Feed	Anodes	Smelters
Alcan
Arvida Prebake	AC-7-EE	70	End-to-end (Pos. end feed)	SW	18	Jonquière
Lynemouth^A	AC-16-EE-M1	160	End-to-end	PF	22	Lynemouth
KK-1 and KK-2^A	AC-16-EE-M2	160	End-to-end	CW	22	Kurri Kurri
KK-3^A	AC-17-EE-M3	175	End-to-end	PF	22	Kurri Kurri
Apex, A-275^A and A-310	AC-28 and AC-31	280 & 310	Side-by-side four side risers	PF	24	Arvida R&D Center^B
Alcoa
N-40 (Niagara)	AA-4	40-80	Side-by-side	CW and PF	24	Mead, Troutdale
AA-4-SE			End riser and Side risers		24 and 26	Renukoot, Vancouver 28
P-88	AA-10-SE3	100	Side-by-side end risers	PF	24	Warrick
T-51	AA-10-SE1	100	Side-by-side end risers	CW and PF	20	Rockdale, Wenatchee
P-75	AA-10-SE2	100	Side-by-side end risers	CW and PF	20	Massena^B
P-100	AA-10	125-130	Side-by-side two side risers	PF	26	Rockdale, Warrick, Wenatchee
P-155	AA-16	155-180	Side-by-side two side risers	PF	24	Badin, Grande Baie, Laterrière, Pt. Henry, Sebree
A-697	AA-18	180	Side-by-side two side risers	PF	24	Mt. Holly, New Madrid, São Luis
P-225	AA-23	225	Side-by-side four side risers	PF	32	Massena, Tennessee
A-817	AA-30	275-300	Side-by-side five side risers	PF	40	Portland
Alusuisse
EPT-10	AS-8-SE	80-130	Side-by-side end risers	PF	22	New Johnsville,^D Salzburger^D
EPT-10	AS-8-EE-M1	80-130	End-to-end	PF	24	Steg, Delfzijl, Straumsvík (Potroom 1 and 2)
EPT-10^C	AS-8-EE-M2	80-150	End-to-end	PF	24	Husnes
EPT-10^C	AS-8-EE-M3	80-130	End-to-end	PF	24	Straumsvík (Potroom3)
EPT-14	AS-14-EE-M1	140-145	End-to-end	PF	26	Essen (Potrooms 1 and 2), Lake Charles,^D Sibenik^D
EPT-14^C	AS-14-EE-M2	140-170	End-to-end	PF	26	Essen (Potroom 3)
EPT-14	AS-15-EE	145-170	End-to-end	PF	26	Hillside
EPT-18	AS-18	180-190	Side-by-side side risers	PF	32	Rheinfelden^D
Comalco and Dubal
CD-200	CD-20	190-206	Side-by-side side risers	PF	20	Dubai, Tiwai Point
Hydro
HAL-150^C	HAL-15-EE-M	160-175	End-to-end	PF	20,22	Årdal, Sunndalsøra
HAL-230	HAS-23	230	Side-by-side four side risers	PF	26, 30	Høyanger, Venalum (line 5), Ziar
HAL-250	HAL-25	250	Side-by-side four side risers	PF	30	Årdal
Kaiser
P-93	KA-6-EE	60	End-to-end	PF	6	Tacoma, Nadvoitsy
P-57^E	KA-9-SE	93	Side-by-side end risers	CW and PF	20	Bell Bay, Ravenswood
P-69	KA-14-SE	140-175	Side-by-side end risers	CW and PF	18	Hollyhead, Dubai, Tema, Hawsville, New Madrid, Tiawai Point, Voerde
P-86	KA-15	150	Side-by-side side risers	PF	16	Sundsvall
P-80	KA-18	180-190	Side-by-side side risers	PF	16	Chalmette,^D Tacoma^D
Pechiney
AP-7	AP-70-SE	70	Side-by-side end risers	SW (Lines A and B = PF)	12	St. Nicolas
AP-9	AP-9-SE	90	Side-by-side end risers	SW (Line C = PF)	16	Auzat, Mostar,^F Slatina, St. Nicolas
AP-LN	AP-9-EM	90	End-to-end end riser and two side risers	SW	20	Lannemenzan
AP-CM	AP-13-EEM	125	End-to-end end riser and two side riser	SW	24	Edéa
AP-13	AP-13-SE	130	Side-by-side end risers	SW	18	Belem, Frederick, Ferndale, Vlissingen
AP-14	AP-14-SE	140	Side-by-side end risers	SW	20	Mostar, San Ciprian
AP-18	AP-18-16	180	Side-by-side four side risers	PF	16	Baie Comeau, Bécancour, Ft. William, Karmøy, Kidricevo, Orissa
AP-18-18				18 (Aluar) smaller anodes		St. Jean-de-Maurienne (F Line), Tomago, Puerto Madrym
AP-30	AP-30-20	300	Side-by-side five side risers	PF	20 (double)	Bahrain, Dunkirk, Sept-Iles, Hillside
				40 (single)		Boyne, Deschambault, St. Jean-de-Maurinne (G Line)
Reynolds
P-6^G	RY-8-SE	75	Side-by-side end risers	CW	28	Alcasa, Arak, Troutdale
Invergordan	RY-14-SE	130	Side-by-side end risers	CW	18	Invergordon^H
P-19^G	RY-16-SE	145-165	Side-by-side end risers	CW and PF	18	Hamburg, Venalum, Alcasa, Santa Cruz
P-19S^G	RY-16	160-170	Side-by-side side risers	PF	18	Alcasa, Hamburg
P-20S^G	RY-17	170	Side-by-side side risers	PF	18	Alcasa, Ikot Abasi
P-23S^G	RY-18	180	Side-by-side side risers	PF	18	Alcasa
VAW
Erftwerk	VAW-11-EE	110-126	End-to-end	SW	Continuous	Stade
CA-120	VAW-12-EE	120	End-to-end	PF	14	Danjiangkou
CA-165^C	VAW-17-EE-M	165-170	End-to-end	PF	20	Bayside, Rheinwerk
CA-180	VAW-18	180	Side-by-side side risers	PF	20	Grundartangi
CA-240	VAW-24	240	Side-by-side side risers	PF	24	Töging^B
CA-300	VAW-30	300	Side-by-side side risers	PF	32	Sayansk^B
Montecatini
P-115	MS-12-EE	115-125	End-to-end	SW and PF	16	Bahrain
P-155	MS-16-EE	155-165	End-to-end	SW, CW, and PF	16	Fusina, Puerto Madryn, Porto Vesme
Elkem
P-155	EK-16	155	End-to-end	SW and PF	18	Mosjøen
Sumitomo
S-170^C	SM-17-SE	185-00	Side-by-side end risers	CW and PF	18	Boyne Island, Kula Tanjung
Egyptalum
P-200^C	EG-20-EE-M	200	End-to-end	PF	24	Nag Hammadi
Venalum
V-350	VN-35	320	Side-by-side four side risers	PF	36	Puerto Ordaz
Russia
C-50	RU-5-EE	50	End-to-end	PF	26	Volkhov
C-125M^C	RU-13-EE-M	125	End-to-end	PF	14	Krasnoyarsk (Line 8)
C-160^C	RU-16-EE	155-165	End-to-end	PF	22	Krasnoyarsk (Line 7), Tadzhik, Kamensk-Uralsky
C-175M2^C	RU-18-M2	175	End-to-end	PF	24	Sayansk, Tadzhik
C-190^C	RU-19-EE	180	End-to-end	PF	26	Sayansk
C-255	RU-26	255	Side-to-side side risers	PF	36	Tajik, Sayansk, Volgograd (four pots)
C-255M1	RU-26-M1
C-255M2	RU-26-M2
C-300	RU-30	300	Side-by-side four side risers	PF	32	Sayansk^B
China
P-60	CH-6-EE	60-75	End-to-end	SW, PF	10-12	^_I
P-75	CH-8	75	Side-by-side one qt. riser	SW	10	Zhengzhoou
P-115	CH-12-EE	115	End-to-end	PF	14	Danjiang^J
P-140	CH-14-SE	135-140	Side-by-side end risers	PF	20	Baotou, Fushun, Qinyang
P-155	CH-15-SE	150	Side-by-side end risers	CW (PF)	26	Baiyin^K
P-160	CH-16-SE-M	160	Side-by-side end risers	PF	24	Guizhou^L
P-160	CH-16	160-180	Side-by-side side risers	PF	24	Pingguo, Qinghai,^M Xinan
P-200	CH-20	185-200	Side-by-side side risers	PF	28	Guizhou, Kunming
P-280	CH-28	280	Side-by-side side risers	PF	40	Qingyang
P-320	CH-32	320	Side-by-side side six risers	PF	48 (20)	Pingguo
SW--side work, CW--center work, PF--point feed. A Magnetic compensation, asymmetric busbars. B Cells not in operation. C Magnetic Compensation. D. Smelter closed. E Assigned by the author. F Partially restarted. G Total anode area (square meters). H Smelter shutdown. I Prebake cells are in the test stage at more than ten smelters for retrofitting Söderberg cells. J Smelter is from VAW Töging, Germany. K Smelter is from Japan. L Nippon Light Metals prebake technology. M Magnetic compensated.

UNIVERSAL PREBAKE CELL NOMENCLATURE
Currently, there is no universal system for the nomenclature and identification of prebake (PB) cell technologies. Aluminum companies use their own naming systems, which differ widely throughout the industry. Thus, the adoption of an acceptable universal prebake nomenclature (UPBN) system is recommended for the naming of future PB cells. Without the adoption of a UPBN system, the names of prebake cells will become even more confused in the future in view of recent mergers by aluminum companies and the renaming of existing PB cells as they are modernized. Whenever possible, the UPBN name should be as brief as possible in describing PB cells. For example, the side-by-side, side-riser PB is the most common type of cell and does not require any special notation; the amperage is shortened by dividing the kA by ten. Thus, Pot or Company Prefix – Amperage (kA)/10 (e.g., AP-18 identifies the cell as a Pechiney Aluminium, 180 kA PB cell). UPBN PB cell nomenclature: Use a company identification prefix (two letters or more) rather than “P” for Pot. Starting potline amperage (kA) is divided by ten; fractions are rounded to the nearest 10 kA. Use “EE” for end-to-end cells; no symbol is required for side-by-side PB cells. Use “SE” for side-by-side, end-riser cells; no symbol is required for side-riser PB cells. Use the number of anodes only when a different number of anodes are used in the same cell design (e.g., AP-30-20 and AP-30-40). Use “M” for magnetic compensation of the busbar system. Use “1, 2, 3 . . .” for different upgraded versions of the same cell design. Using these guidelines, the Kaiser P-69, becomes KA-15-SE (Kaiser, 150 kA, side-by-side, end-riser PB cell) and the Alcoa A-697, becomes AA-18 (Alcoa, 180 kA, side-by-side, side-riser PB cell).