A Case Study of Energy Conservation Opportunities in Copper Refining

W. E. Somers, L. Kurylko, J. R. Stone and Marvin L. Hughen

SUMMARY

A study of energy usage and distribution in a copper refinery was conducted in an attempt to determine possible cost savings in operations of the plant. The study covered those processes which were the major users of energy, namely, smelting, anode casting, electrolytic refining, steam genera­tion and distribution, and electricity distribution.

The study involved obtaining data of mass and energy flows in the refinery; identifying energy conservation opportunities (ECO's); obtaining price, operating costs, and saving potentials for each conservation measure; and analyzing the economical viability of each conservation pro­posal. Potential cost savings were found to be substantial in heat recovery from slag and anode furnace hot gases, modi­fication of the central steam supply system, control, and redistribution of electrical loads, insulation of electrolytic tanks, and changes in the atomization of oil.

INTRODUCTION

United States Metals Refining Company (USMR), Car­teret, New Jersey, experienced high fuel and electric power costs and employed Energy Engineering Corporation, Jersey City, New Jersey to conduct an energy usage sur­vey of the processes using the greatest amount of fuel or electricity to determine if the energy in these forms was being used to the greatest advantage. The smelting and refining company also asked for other recommendations for better energy utilization that would not require any basic changes to the processes.

From plant records, it was found that the smelter, anode casting (tough pitch), electrolytic refining, steam genera­tion and distribution, and electric distributive processes were the greatest energy users. The survey was confined to these processes.

This paper describes the program planned and conducted to obtain the desired information and to develop the eco­nomics of energy conservation opportunities uncovered during the survey.

PLANT DESCRIPTION

General The equipment used in the departments to which the

survey was confined has been in service many years. It has undergone extensive maintenance and many modifications to adapt to changes in fuel and to meet emission standards established by the state environmental protection agency.

Smelter The major equipment used in the smelting process con­

sists of a coke-fired cupola, a cupola air blower, a settler, an electric arc furnace, a converter, a converter blast air

JOURNAL OF METALS· July 1982

blower, three baghouses with fans, an arc furnace slag granulating launder, and slag ponds.

Figure 1 diagrams the smelting process in this refinery. A description of each of these pieces of equipment or sys­tems is provided in Appendix A.

Anode Casting (Tough Pitch) The equipment used for anode casting consists of four

oil-fired reverberatory furnaces, four anode casting wheels, four waste-heat recovery boilers, a baghouse with fans, and necessary charging machines.

Figure 2 shows a typical diagram for one of the four furnaces. Appendix B includes descriptions of this equipment.

Electrolytic Refining The electrolytic refining processes employ the following

equipment or systems:

• 5. rectifiers of varying capacities, • necessary copper bus bars to supply DC to the electro-

lytic cells, or tanks, in five electric circuits, • 1,786 cathode production tanks, • 30 liberator tanks, • 128 copper powder production tanks,

• electrolyte, • 4 filter presses, • 5 electrolyte transfer pumps, and • 14 steam-heated electrolyte heaters.

This equipment is described in Appendix C.

Steam Generation and Distribution Steam is generated by four waste-heat recovery boilers

associated with the four reverberatory anode furnaces, and two oil-fired power plant boilers.

Steam is distributed for process and heating purposes by two piping systems. One is for high-pressure (150 psig) steam. The second is for low-pressure (6 psig) steam. Figure 3 shows a simplified diagram of the steam distribution system.

Electrical System The electrical power is delivered by the local utility over

two lines to a main switchyard. A loop bus distributes the power to 20 substations and 7 major power stations using pieces of equipment through 3 switchyards within the plant.

PLANT PROCESS DESCRIPTION

The plant raw materials consist of telephone scrap, insulated and bare wire, residues, converter and anode furnace slag, baghouse dust, and other copper-bearing scrap.

These raw materials are melted and partially refined in the Smelting Department in which the coke-fired cupola, settler, electric arc furnace, and converter are used to form

41

AIR 'POlLUTION CON1J:IOl BAGHOUSE

GASlO STACI(

i _! ,cx b J

REFINERY r------SU\G AND

FLUXES

~" ~'I ~~LUTION CONTROL BAGHOUSE

7

BLACK COPPER

Figure 1. United States Metal Refining Company's copper smelting process.

OUTSIDE BLISTER

~ SCR AP CHARGE

BLISTF.R

=0 0 0-0'-' ~~:.LUTION r--~ rOlllROL I BAGH OUS[

GASES .• -:..-==>---

ST 11M ---Ir- rot.tIIJr.

IICADER

",,"---WATE R

'''OD[

TO ELECTROLlTlC

_ h REFINING

Figure 2. Anode furnace operations.

blister copper having 95% Cu content. This is cast into large cakes' for charging reverberatory furnaces in the next refining process.

Particulates must be removed from the off-gases from the smelting process in order to comply with local air quality requirements. Bag filter houses are used for the purpose. The gases are cooled to 350°F by spray water in order to protect the bag material.

The blister copper cakes are combined with bare wire scraps, anode scraps, cathode scrap (both from the electro­lytic refining process), and other copper scraps to charge oil-fired reverberatory furnaces. In these reverberatory furnaces, the charge is melted and further refined before being cast into anodes for the electrolytic refining process. These anodes are about 98.5% Cu.

The effiuent gases from each reverberatory furnace are cooled by a waste-heat recovery boiler located above the furnace gas outlet. Particulates are removed from these gases in a common bag filter house. The gases are further cooled by water spray before entering the baghouse.

The anodes are used in the electrolytic refining tanks where high-purity copper is deposited on blanks to form cathodes that may be melted down and cast into bars in plant or sold for use external to the plant.

Steam generated in the reverberatory furnace waste-heat recovery boilers is supplemented by the output of the two oil-fired boilers in the power house.

42

All the steam is fed into the high-pressure steam distri­bution system. Some is used in plant processes, while some is reduced to 6 psig to supply the low-pressure heating and process steam system. Some of the pressure reduction is through small turbines driving the power house boiler auxiliary equipment as well as through pressure-reducing valves. The remainder of the required low-pressure steam is obtained by pressure reduction through a valve, followed by de superheating.

SURVEY PROCEDURE

An energy use survey team was formed, consisting of

• a professional engineer, familiar with energy use and conservation, as field leader;

• a metallurgical chemist, familiar with the processes being studied;

• an electrical engineer, familiar with electric distribution and control systems and equipment; and

• a professional engineer, familiar with energy use and conservation, as office coordinator.

. The refinery gave the team access during normal opera­tion to all parts of the processes and systems included in ~he study. Field data were collected through useofrefinery Instruments, refinery records, and discussions with operating personnel. The refinery instruments were supplemented by the team's thermocouples and temperature recorder semi-continuous gas analyzer, Orsat apparatus,. watthou; meter, voltmeter, and ammeter. These were used to check normal instruments and to obtain additional readings when no existing instruments were available. A typical record of data obtained in the field is shown in Figure 4.

Energy and material balances were developed from the data collected. (An abbreviated energy and material bal­ance is shown in Figure 5.) Balances of this type show where energy losses occur and give an indication of the possibility of loss reduction or recovery. The team mem­bers were alert to such energy conservation potentials, as well as to physical limitations to their implementation.

RESULTS OF ENERGY SURVEY

Analysis of the data obtained by the survey team indicated several zones of potential energy conservation. These zones were indicated for each process included in the survey:

• Smelting process - effiuent gases, slag, cooling water, and molten blister copper.

JOURNAL OF METALS· July 1982

• Anode casting process - effiuent gases, steam atomization of fuel oil, and melting of solid charge.

• Electrolytic refining processes - reduction of shorts, reduc­tion of stray current, reduction of contact electrical losses, and improvement of electrolyte heating.

• Steam generation and distribution processes - elimina­tion of hard-to-control space and water heating by steam; use of other means of fuel oil atomization; and increase efficiency of essential steam-heated heaters and dryers.

• Electrical distributive processes - increasing motor driven equipment efficiency; correction of load distribution through existing transformers; and reducing peak demand by load shedding.

From these indications the team proposed ways to achieve the conservation potentials, which they called Energy Con­servation Opportunities (ECO's).

ENERGY CONSERVATION OPPORTUNITIES (ECO'S)

For each ECO considered, the maximum potential energy saving, expressed in Btu's/day or kWh/yr, was calculated using the data collected by the field team.

The next step was to develop an inquiry specification for any new major equipment or modification of existing equip­ment necessary to obtain energy conservation.Capital cost estimates for implementing each ECO were based on estimating proposals received in responses to these inquiries. Estimating costs for smaller, more or less standard, equip­ment was frequently obtained by conferences or telephone calls to vendors, rather than by means of inquiry specifications. The estimate of annual costs for each ~CO includes:

• standardized annual amortization charges, subject to mod­ification by the plant management to fit their corporate pattern;

OFFICES - ........ .:....._ ....... -..., !gr., /

/

OFHC PLANT

/' TANI<

HOUSE

• standard annual tax and insurance costs, subject to mod­ification by the plant management to suit their conditions;

• annual energy charges attributed to the modifications; • annual operating costs, applied where the ECO required

a change in the number of operating personnel (the current annual cost per operator position was used); and

• an annual charge of 2.5% of the capital cost, in cases where new or modified equipment was expected to require maintenance in addition to the requirements for existing equipment and conditions.

The difference between the present annual energy cost and the estimated annual cost was estimated to be annual savings that would be realized by implementing the ECO. Those ECO's indicating a possible annual saving greater than 7% of the capital cost of implementation were recommended for closer study in order to develop deta.iled designs and estimates prior to implementation.

The ECO's were summarized in tables for categories of major ECO's recommended, minor ECO's recommended, and ECO's with low priority or not recommended. Table I is an example of a typical table. Major ECO's were those requiring a capital expenditure in excess of $100,000, while minor ECO's were those requiring up to $100,000 in capital expenditure. These were summarized more briefly with savings expressed as percentage of capital cost in tables (See Table II).

ECO's recommended, by processes, include:

Smelting Process 1. Replace cupola off-gas cooling spray water with a waste­heat recovery boiler. This would supply steam to the plant steam system, reducing fuel now burned for this purpose, and eliminate water consumption for cooling the gases before entering the baghouses. Electric energy required for pumping this water would also be eliminated. 2. Replace arc furnace off-gas cooling spray water with a cupola air preheater. This would shorten the melting time

NO.1 WHB

"" NQ~B

___ ..._---lI--I-....... -----................ -..._r-----NO.--,3 WH,\ GATE \ HOUSE Il00"

Figure 3. Steam distribution system.

JOURNAL OF METALS· July 1982

MAl Nt SHOPS

SMELTER

~1 ~-.---_/

L-. _____ ,- CENTRALIZED STORAGE

WHITE METALS PLANT

43

in the cupola by the addition of heat, and thus increase cupola output. 3. Use hot granulation water to heat the electrolytic refining electrolyte to recover heat from the arc furnace slag granu­lation. Known equipment and technology would be used for this process. This would eliminate a large portion of the plant steam usage, saving fuel now burned for generating the needed steam.

1400

~ en 1200 III II:: ::I

~ 1000 II:

"" Q.

~ 800 .... en ~ 600

III

~ II:

" Z

~

400

500

o

,.. 500

I

f\ /

rv-\A '.' KI 1//( ./

~\ nJ W

'"'vlfLlt . ~~

I 2

l

,J,

\ ~J\ \

h\ Yin !

\1 I !~!~ \ ;

! i I

I iJ ~

.,.., it L -O\J

3

il("V

t W"...

-JlJ1,r

5

I

r-.,LEAVING HE TRANSFER

AT SECTION

t.EAV;NG pt.i NUM R ASOVE SOILE

ENTERING I EXHAUST OU CT

I I

I-CHARGING AN o RECHARGING G MEt.TOOWN

SKIMMING Z-Ft.AT DURIN 3-0"I'-IOTTOM 4-FLOPPING ... NO POLING 5-f.ASTING

IV

o o 6 12 18 24 30 36

ELAPSED TIME FOR CHARGE-HOURS

Figure 4. Typical field data record.

2587 T/D(51"!. OPER.l 95000 ACFM 112.4x lOS BID

STEAM TRACING

WATER

20.2 TID _ 40.4x 108 M>

(,...,1-----1 CONVERTER 14-"-----..;'"---1\ BAGHOUSE N

500HP .."" 10 T/D 560 TID

4. Install new properly sized motor-driven converter air com­pressor with starting gear suitable for five or six starts per day. This would replace the existing oversized blower, which was being operated inefficiently out of necessity because of the inability of the present motor starter to withstand frequent starts.

Anode Furnaces 1. Install air heaters to cool waste-heat recovery boiler effiuent gases before entering the baghouse. This would preheat the reverberatory furnace combustion air. The melting period of the furnace cycle could be shortened with resulting fuel saving. In addition, gas cooling spray water and pumping power would be eliminated.

Electrolytic Refining Process 1. Insulate tanks to reduce heat losses. This would aid in keeping the electrolyte at optimum temperature, thereby increasing the process efficiency and reducing electrolyte heating demand. 2. Optimize electrode spacing and current density to min­imize shorts and increase productivity. 3. Use a different type of bus bar to reduce contact losses and reduce labor in correcting shorts.

Steam Distribution System 1. In addition to those already mentioned as ways to reduce steam consumption, ECO's for the steam distribution system involved were largely reducing the extent of the distribu­tion system and its attendant losses and maintenance costs by using locally installed and controlled space and water heating sources at several locations in the plant. Where steam is required for some processes, high efficiency gas or oil-fired steam generators were recommended. For inter­mittent heating, such as space and water heating, electric or gas-fired heaters were recommended. These recommen­dations required energy sources other than steam and No.

SAND

51 TID o'¥l

270.1 TID 169.2x106 B/O

20.5 TID SHOT

4.7 TID

BLACK COPPER FROM SETTLER AND ELECTRIC FURNACE

3.2 TID 7 4.2 ~ lOs B/D

COKE

0.4 TID Ole 10' BID

REFINED BRASS Ox 10· BI'Il

AM AX BULLION O.2xI06 B/D INFILTRATION"

303 TID 11000 CFM CONVERTER 10.2 x 106 BID

L-------l/ J--r--_---~ QUACT.=313.0X 1Q6B,ID

(HEAT RELEASE)

WALL LOSSES 29.lxI08B/D

AIR AND STEAM FROM GRANULATING LAUNDER

TO CUPOLA

2500 HP

DUMP

345+ TID

Oz GAS .... --------I

OXIO·B/D

Figure 5. Converter energy and material balance.

O(NOM.) T/D Ox 10· BID 184.3 TID

246.6 x I ()6 BID

246.6)110'B/O

11.2 x 1()6 BID

167.4 TID 106.5xlo'B/D

CONVERTER RESIDUE 8.4 TID 11.2 x 106 BID

c=J--.TO TOUGH PITCH

44 JOURNAL OF METALS, July 1982

6 fuel oil, but the efficiency of the proposed equipment and the ability to be controlled locally resulted in more effi­cient energy use and lower annual costs. 2. One ECO associated with reduction of steam usage involved using hot water from the cupola cooling jackets for space heating. Although usable for only part of the year, this scheme seemed economic and therefore was recommended.

Electric Distribution System 1. Redistribute loads to obtain more efficient utilization of transformers. This involved shifting some loads to trans­formers not fully loaded, thereby making possible discon­tinuing use of some very lightly loaded transformers. It also involved reducing loads on some excessively loaded transformers. 2. Use either of two alternative methods of cogeneration: • Use large back-pressure turbine in place of present pressure reducing valves and small turbines to obtain

9 psig steam as indicated in Figure 6. The turbine would drive an electric generator to reduce electric demand on the utility. This would require continued and greater use of the power house boilers. • Use a gas turbine and combined cycle as shown in Figure 7. Some electric energy would be generated by a gas-turbine-driven generator, with a back-pressure-tur­bine-driven generator. The output of the heat-recovery steam generator of the combined cycle would supplement the output ofthe reverberatory furnace waste-heat recovery boilers so the powerhouse boilers would not be needed.

The choice between these two alternatives requires fur­ther cost evaluation as applied to this installation. 3. While some electric loads cannot be reduced, their cost could be reduced by scheduling the maximum demands during the utility off-peak periods. 4. Monitor and schedule electricity usage closely to reduce unnecessary usage to which most plants of any type are

Table I: Energy Consumption and Conservation Potential Economic Analysis Process Unit: Steam

Energy Present Energy Equipment Min. Expected Conservation

Energy Usage Annual Efficiency, % Energy Usage Potential ECO Costs

Conservation Energy, Exp. Cost, Annual Option(ECO) $1,0001 Ind. $1,0001 kWhl Savings, Capital Savings Savings,

kW yr USMR Avg. kWh/yr ~ ~ $1,OOO/yr $1,000 $1,OOO/yr $1,OOO/yr Area 4-Copper Cast-ing (Tough Pitch) Area WHR boiler blowdown

heat recovery 59 171 36* 106 From steam 22 65 21 4 61 From water 4 11 11 Atomizing steam

replacement 47* 138 72 196,000 10 128 40 18 110 Drill room water and

space heating 2* 4.5 72 84 4 3 11

TOTAL AREA 4 26 204 65 25 183

*106BtuiDay

Table II: A Partial List of Major Energy Conservation Opportunities

ECO No.

1 2

4 5

6

10

12

13 19

ECO Description

Smelter Cupola Offgas heat recovery boiler Cupola combustion air supply

Smelter Arc Furnace Copula combustion air heater Heat recovery from slag,

electrolyte heating

Note: Based on present cost of heating electrolyte

Smelter Converter Converter air supply

Anode Furnaces Furnace combustion air heaters

Electrolytic Refining Optimize electrode spacing

Use cup-type bus bars Insulate tank walls

Estimated Estimated Annual Savings

Capital Cost, %Capital $1,000 $1,000 Cost

2,000 140 7 125 9 7

150 90 60

725 735 100+

325 30 9

930 724 78

Recommended tests are necessary to determine savings possible.

1,200 800

100 769

8 96

Note: Replace tank walls at regularly scheduled tank rebuilding to avoid excessive outages and extra cost of removing present walls.

JOURNAL OF METALS· July 1982 45

prone. Equipment to do this is available and can be very simple or very sophisticated. A simple installation was recommended.

Several ECO's that were studied and which were shown on the summary tabulations were not recommended. The first option explored for recovery of heat from slag was air granulation of arc furnace and converter slag, using the heated air to generate steam in a heat recovery boiler. It was found that technology for such a process is not availa­ble, although there were indications that some companies are working on development of it. Since management did not wish to be involved in a development situation, this was not recommended.

Another alternative method for heat recovery from slag granulation is being studied in which molten salt is heated by the slag and the heat is used to generate steam. The slag requires further cooling in a water bath which furnishes low-level heat for space or process heating. This was not recommended to USMR management because of its develop­mental nature and because another alternative for re­covering heat from slag was found (the heating of the electrolytic process electrolyte discussed as one of the recommended ECO's for the smelting process). However, work is continuing with the Department of Energy to develop molten salt to slag granulation and heat recovery for application where use of heat in slag granulating water is not possible or feasible.

Dry granulation, by air, of blister copper from the converter was considered, but was not recommended for the same reason given for not recommending air granulation of slag. Wet granulation does not seem practical because it would introduce entrained moisture into the furnaces. Use of heat in converter effluent gas to preheat converter blowing air did not appear to be economical, so it was not recommended.

The molten charging of plant blister copper to save fuel required to remelt it in the reverberatory furnaces was

studied. Although there is equipment available to imple­ment this ECO, the alterations to existing equipment to permit use of the new equipment was prohibitive. Even assuming that the old and new equipment could be made compatible with a minimum expense, the return on the capital expenditure was to low for this scheme to be recommended.

Other cogeneration cycles were studied but did not prove as economical as either of the two recommended for fur­ther study. An ECO briefly considered but not reported was the use of a waste-heat recovery boiler to cool the converter effluent gases. This was not pursued because of the cyclic nature of the converter opeation and the corresponding cyclic output of such a boiler.

Because many ECO's were interrelated, where the implementation of one might change the economics of another, it was not possible to estimate possible total annual savings from their implementation. However, there was indication that 15-20% of the present annual energy cost could be saved from these ECO's making possible recovery of the capital cost in two to three years. This, of course, depends on the extent of implementation of the recommended ECO's.

In view of ever increasing costs of energy and its availa­bility, changing interest rates, tax laws, equipment costs, etc., it may be necessary to reconsider at a later date some of the ECO's, which are presently deemed uneconomical.

CONCLUSION

To our knowledge, this is the first extensive energy usage and conservation survey made in the copper refining industry. Until such a survey is made, there is no way of knowing the energy saving and cost reduction possible at each installation. The survey recently completed and reported here indicates the possibility of significant savings.

A review of the data presented herein indicates the signi-

150 PSIG 430"F _,.--__ ' 140PSIG I · .2.7!5U" .. LBM'

Figure 6. Cogeneration alterna­tive 1.

Figure 7. Cogeneration alterna­tive 2.

46

MAIN BLR. HRSG'S

50.2/65.0XIO'L8/HR

42.5/66)1101 LB/HR

PRY 1325/2055 KW

9PSIG -.: __ -+-___ ,.----L--~=.:..::.-__+ 31/48.8)110' LB/HR

14/20x IO'LB/HR

FLASH TANK

~'50 ~_G_4_30_·_F_ ...... _____ --. ___ --.r-__ '_4_0_P_S_IG_+42.7/59.8 xlQ' LBMR

42.5/66XI01 LB/HR

PRY 1325/2055 KW MAIN BLR. HRSG'S

HRSG

GAS TURBINE

9PSIG -.,,----4------._--'------_ 31/48.8)110' LB/HR

FLASH TANK

o 6990/U600KW

GEN.

14/20xIO'LB/HR

JOURNAL OF METALS· July 1982

ficant quantity of energy that is potentially recoverable during the cooldown of slag. While not specifically high­lighted in the present study, much study work has gone into the problems associated with the recovery of heat from slag during slag cooldown. The authors would welcome an opportunity to share this work with any interested firm.

APPENDIX A

Smelting Department Equipment

A. Cupola 1. Coke fired. 2. Tapered furnace shaft 21 ft, 8 in. long x 14 ft high

with width varying from 7 ft, 6 in. at charge door to 9 ft at bottom.

3. Includes Condors knockout chamber and gas outlet down comer.

4. Furnished with 112 water-cooled steel jackets of varying size, shape, and duty.

5. Furnished with bustle pipe feeding 24 4-in.-diame-ter tuyeres.

6., Uses air-enriched to about 4% 02. 7. Skip hoist bin with charge material including coke. 8. Bin discharges to charge cars which dump charge

into furnace. B. Cupola air blower

1. 400 hp Ingersoll Rand blower. 2. 14,000 cfm, 2 psig, ambient. 3. With inlet damper and dump valve to insure stable

operation. C. Settler

1. 26 ft, 3 in. long x 13 ft, 3 in. wide x 10 ft high. 2. Brick with suspended tile roof. 3. 25-30 gallh oil burner.

D. Electric arc furnace 1. 80 ton, 6000 k V A Swindell-Dressler refractory -lined

arc furnace. 2. 28 ft, 9 in. long x 16 ft, 9 in. wide x 11 ft, 9 in. high

with three 2-ft OD graphite electrodes. E. Converter

1. No.2 Pierce-Smith cylindrical convertor, 17 ft, 4 in. x 10 ft OD with pinion drive for tilting for charging or tapping through a 6 ft, 6 in. x 4 ft, 6 in. oval opening.

2. Equipped with a bustle pipe and 25 1 V4-in.-dia­meter tuyeres for the introduction of blowing air.

3. Charging is by means of a traveling crane with an approximately 18 T ladle filled by tapping the settler and electric arc furnace.

F. Converter blower 1. 30,000 cfm, 17 psig discharge pressure, 2,500 hp

motor-driven Elliott compressor. ' 2. Inlet damper and discharge dump valve to insure

stable operation. 3. Normal air use rate is 10,000-14,000 cfm during

converter blowing proceeds. 4. Blowing period is about 50% of converter operating

time. 5. Blower and motor operate at about 59% overall

efficiency. G. Baghouses

1. Two Wheelabrator baghouses to remove particulates from the cupola effiuent gases. a. One baghouse, carrying the base load, is divided

JOURNAL OF METALS· July 1982

into six separate sections each with 480 20-ft-x-8-in. diameter fiber-glass bags. It is furnished with a 300,000 cfm, 16-in.-H20 static pressure fan with a 1,000 hp motor drive. b. One baghouse, handling varying amount of excess

cupola gas effiuent, is divided into 8 sections, each with 480 20-ft-x-8-in. diameter fiberglass bags. 1) Gas inlet control damper accommodates the

varying gas flow. 2) One 260,000 cfm, 225°F, 6-in. H20 static

pressure fan rates at 350 hp handles the gas flow through the baghouse.

3) A 270,000 cfm, 250°F, 6-in. H20 static pressure fan rated at 500 hp supplements the previously described fan.

2. One six-section baghouse; each section with 272 20-ft-x-8-in.-diameter Nomex bags, is used to clean the arc furnace effiuent gases. a. All six sections are equipped with 19,000 cfm, 250°F, 1O-in.-H20 static pressure fans with 150 hp motors.

3. Effiuent gases from the converter are cleaned by a baghouse having 8 sections, each with 416 20-ft-x-8-in.-diameter bags. a. A 13,000 cfm, 350°F, 12-in. H20 static pressure

fan with 500 hp motor pulls the gases through the baghouse.

4. The cupola, arc furnace, and converter effiuent gases must be cooled to 350°F in order to obtain reason-able baghouse bag life. This is done by spraying water into each gas stream. In addi­tion, provision is made for introducing temper­ing air into the cupola off gas stream to control temperature at the baghouse inlet. a. Pumps are provided to pump spray water.

H. Slag granulating launder 1. Slag is granulated by pouring into a fast-moving

water stream in a launder. 2. Granulated slag is collected in two storage pits. 3. Two pumps recirculate granulating water from stor­

age pits to granulating launder. 4. Slag is removed from the storage pits by crane and

clam shell bucket for disposal as land fill.

APPENDIXB Anode Furnace (Tough Pitch)

Department Equipment

A. Reverberatory furnaces 1. Two furnaces each consisting of a brick-lined steel

shell 55 ft long x 15 ft. 8 in. wide x 10 ft. 9 in. outside dimensions with inside dimensions about 45 ft long x 13 ft, 7 in. wide, having a nominal capacity of 400 T. a. Equipped with four 6 ft x 3 ft, 6 in. charge doors

on one side. b. Fired with No.6 fuel oil by two North American

burners at one end. c. Equipped with three skim doors located in

the end opposite the oil burners. d. Equipped with tap located in the side opposite

the charge doors. e. Molten copper is tapped into a double ladle­

weighing unit from which it is cast into anodes on a 40-ft-diameter horizontal casting wheel.

f. Furnace is equipped with water-cooled steel skew­backs and cast copper water cooled jackets at the charge door jams, skim door, and buckstays.

2. One furnace similar to the aforegoing two, having outside dimensions at 45 ft long x 16 ft, 8 in. wide x 11 ft, 8 in. high with inside furnace dimensions

47

about 37 ft, 6 in. long x 13 ft, 7 in. wide, having a rated capacity at 360 t. a. The charge doors are 6 ft, 4 in. x 2 ft, 10 in. b. Three Bliss-type oil burners are used at one

end. 3. One furnace similar to the aforegoing having out­

side dimensions of 57 ft, 11 in. x 16 ft, 8 in. x 13 ft, 11 in. high, with inside furnace dimensions about 47 ft, 2 in. x 13 ft, 7 in. having a rated charge capacity of about 400 t. a. One Hauck burner is located at one end of the

furnace. 4. Each of the reverberatory anode furnaces is equipped

with a waste-heat recovery boiler into which the furnace uptake flues at the skimbay end of each furnace discharges the effiuent gases. a. One furnace has a Babcock & Wilcox boiler

rates at 50,000 lblh steam at 700 psig, saturated. b. One furnace has a Babcock & Wilcox boiler

rates at 20,000 lblh steam at 120 psig, saturated. c. One furnace has a similar boiler with the same

rating. d. One furnace has a Walsh & Weidner boiler with

the same rating. 5. The anode furnace effiuent gases from all four

waste-heat recovery boiler gs outlets are taken to a single 20-section International Clean Air baghouse. a. Each section has 180 23-ft-x-8-in.-diameter

fiberglass bags. -b. Each section is equipped with a 13,000 cfm. 24-

iri.-H20 static pressure fan with a 60 hp motor to pull the gas through the section.

c. The baghouse is equipped with a lime handling and injection system to protect the bags from corrosion by the gases.

d. To prevent baghouse failure because of exces­sive gas temperature, the gases are sprayed with water to keep them below 350°F. Spray nozzle piping and pumps are installed for this purpose.

APPENDIX C Electrolytic Refining Equipment

A. Rectifiers 1. a. Three Udylite Megaverters

b. Each rated at 300 V, 5,274 A, 6 hp, AC converting to 300 V, 5,400 kW, 28,000 A, DC.

c. Each equipped with thyristers for periodic current reversal.

d. Each supplies one of three main circuits labelled X, Y, and Z in electrolytic refining house.

2. a. One Udylite Megaverter rated at 200 V, 2700 kW, 13,500 A, DC.

b. Supplies current for the copper powder section. 3. a. One Westinghouse rectifier rated at 75 V, 90

kW, 12,000 A, DC. b. Supplies current to the copper liberator tanks in

the tank house. B. Bus bars

1. Two 6 2/3 in. x 1 112 in. rectangular copper bus bars for X, Y, and Z circuits.

C. Electrolytic tanks (cells)

48

1. a. There are 690 tanks in circuit X, 526 in circuit Y, and 570 in circuit Z, a total of 1786 tanks.

b. Arranged in separate sections of 38-58 tanks. c. The prefabricated concrete tanks are 11 ft long x

42 112 in wide by 44 in. deep. They are lead lined with yellow pine boards under the bottom liner.

d. Each tank contains 31 - 650 lb anodes from the

anode casting process and 32 cathodes arranged in combined series, parallel array.

2. Three rows, A, B, and C, of 10 tanks each. a. Supplied by 75 V, 90 kW rectifier. b. Known as liberator, or copper removal, cells.

3. Eight sections, 16 tanks each. a. Supplied by 200 V, 2700 kW rectifier. b. Wood tanks. c. Lead cathodes. d. Produce copper powder.

D. Electrolyte 1. About 6 million liters of electrolyte are recircu­

lated every 24 h through the electrolytic process tanks. This consists of a water solution of copper sulfate (CuS04) and sulfuric acid (2S04) with some addi-tives, including glue.

E. Auxiliary equipment 1. Four filter presses for continuously filtering the

electrolyte. 2. Five stainless steel Worthington, 17,000 gpm elec­

trolyte transfer pumps. 3. Fourteen 6-psig steam-heated electrolyte heaters.

a. Two Graham Smid Model 43 titanium plate and frame type heaters.

b. Six Kearney Industries Karbate-type tubular heaters.

4. Steam siphons, using 150 psig steam, for removing spills and leaks from tank house cellar floor.

APPENDIXD Steam Generation &

Distribution Equipment

A. Oil-fired boilers 1. Two Babcock & Wilcox integral furnaces. 2. 120,000 lblh. 3. 700 psig maximum allowable working pressure. 4. 700°F. 5. Designed for pulverized coal firing, modified for

No.6 oil firing. B. Waste-heat recovery boilers

1. One anode furnace. a. Babcock & Wilcox b. 40,000 - 50,000 lblh. c. 700 psig maximum allowable working pressure.

2. Two anode furnaces. a. Babcock & Wilcox. b. 10,000 - 20,000 lblh. c. 160 psig maximum allowable working pressure. d. Saturated.

3. One anode furnace. a. Walsh & Weidner. b. 10,000 - 20,000 lblh. c. 160 psig maximum allowable working pressure. d. Saturated.

4. All waste-heat recovery boilers are preceded by a refractory "dutch" oven for the combustion of unburned combustibles leaving associated anode furnaces.

5. Emission control a. One International Clean Air Baghouse for all

anode furnace waste-heat recovery boilers. b. Twenty sections, 180 23-ft-x-8-in.-fiberglass

bags per section. c. Cleaning by reverse air and mechanical shaking. d. Lime additive to gas streams to protect bags

from corrosion by gases and help prevent burn­ing of bags.

e. Induced draft fan for each section. 1) 13,000 cfm. 2) 24 in. H20 static pressure.

JOURNAL OF METALS· July 1982

3) 60 hp motor. rated, steam to points of use. 6. Gas cooling sprays. 2. Low-presure steam.

a. Waste-heat recovery boiler effluent gases are cooled to 350°F before entering baghouse by water sprays.

a. Pump and fan 150 psig throttle pressure turbine drives exhausting into 6 psig, saturated header.

b. Spray system consists of spray nozzles, piping, and pumps.

b. Pressure- reducing valves from 150 psig to 6 psig, supplementing back pressure turbine exhaust.

C. Steam distribution 1. High-pressure system. Necessary headers, branches,

and valves required to distribute 150 psig, satu-

c. Necessary headers, branches, and valves required to collect and distribute 6 psig steam to points of use.

ABOUT THE AUTHORS

William E. Somers, Energy Engineering Cor­poration, Springarn Building, 665 Newark Avenue, Jersey City, New Jersey 07306.

Mr. Somers received his BS and MS in mechanical engineering from Lehigh Universi­ty, Bethlehem, Pennsylvania. Most of his pro­fessional career has been spent with the Public Service Electric and Gas Company, Newark, New Jersey, where he specialized in all phases

John R. Stone, Energy Engineering Corpora­tion, Springarn Building, 665 Newark Avenue, Jersey City, New Jersey 07306.

Mr. Stone received his undergraduate degree from Hiram College, Ohio and his MS in physi­cal chemistry from Williams College, Massachu­setts. He has been involved in the chemical and metallurgical fields with The New Jersey Zinc Company and Asarco. As staff member of

of the engineering of large utility-size power plants. He presently serves in various technical capacities at Energy Engineering Corpo­ration and served as project manager of the project discussed in this article.

Energy Engineering Corporation, he served as field investigator for the project discussed in this paper. He is a member of The Metallur­gical Society of AIME.

Lubomyr Kurylko, Energy Engineering Corpo­ration, Springarn Building, 665 Newark Avenue, Jersey City, New Jersey 07306.

Dr. Kurylko received his undergraduate degree from Syracuse University, masters degrees from both Syracuse and Princeton Universities, and PhD from the Pennsylvania State University. He served for ten years as associate professor of mechanical engineering at Stevens Institute

Marvin L. Hughen, Manager, Plant Energy Con­servation Program, United States Metals Refining Company, Carteret, New Jersey.

Mr. Hughen received his BS in metallurgical engineering from the Missouri School of Mines. Before joining USMR, he worked for Blackwell Zinc Company, Inc., Blackwell, Oklahoma. He joined USMR in 1969 and served several years in the Tough Pitch Department and later as an

of Technology. As staff member of Energy Engineering Corporation, he served as principal field investigator for the project discussed in this article.

assistant to the vice president of technical services. He also served as manager of the Plant Energy Conservation Program which is described in this article.

(~ * ".'lUI;a'iiP/IIt.' (continued from page 33)

Research Dept., Asarco Inc., 901 Oak Tree Road, South Plainfield, New Jersey 07080; telephone (201) 756-4800; George Foo, West­ern Electric Co., Engineering Research Center, P.O. Box 900, Princeton, New Jersey 08540, telephone (609) 639-2545; or Winston W. Liang, Standard Oil Co. (Indiana), Amoco Research Center, P.O. Box 400, Maperville, Illinois 60566, telephone (312) 420-5120.

Process Mineralogy

Abstracts are due by July 31, 1982 for sessions sponsored by the Joint TMS/SME­AIME Process Mineralogy Committee at the 1983 AIME Annual Meeting. The sessions will cover topics on applied mineralogy to mineral processing, extraction metallurgy, refractory materials, energy minerals, and exploration for ore deposits, and general topics on applied mineralogy.

Submit titles (June 30) and abstracts (July 31) to William Petruk, Chairman, Process Mineralogy, CANMET, 555 Booth St., Ottawa, Ontario, Canada KIA OG1.

pyrometallurgy

Abstracts are due by August 1, 1982 for sessions sponsored by the TMS pyrometal-

JOURNAL OF METALS· July 1982

lurgy Committee at the 1983 AIME Annual Meeting. Topics will include slag treatment in copper and nickel smelting, developments in anode refining and casting, and general pyrometallurgy emphasizing current and innovative plant practices.

Submit abstracts on the appropriate TMS­AIME abstract forms to Philip J.- Mackey, Noranda Mines Limited, 240 Hymus Blvd., Pointe Claire, Quebec, Canada H9R IG5; telephone (514) 697-6640.

Superalloy Behavior in Corrosive Environments

Abstracts are due by August 1, 1982 for the symposium, Superalloy Behavior in Cor­rosive High-Temperature Environments, sponsored by the TMS-AIME High Temper­ature Alloys Committee at the 1983 AIME Annual Meeting. Papers are sought on field service experiences in gas turbine, coal con­version and combustion, waste incineration, low-grade fuel usage, etc.; comparison of superalloy capabilities and performances in high-temperature environments; etc.

Submit abstracts of up to 200 words on the appropriate TMS form to M.F. Rothman, Technology Dept., Cabot Corporation, 1020 W. Park Ave., Kokomo, Indiana 46901, tele­phone (317) 456-6223.

GENERAL MEETINGS

Chevron-Notched Specimens

Abstracts are due by October 30, 1982 for a symposium on Chevron-Notched Spec­imens: Testing and Stress Analysis sponsored by ASTM, to be held April 21, 1983 in Louisville, Kentucky. Topics are sought in the following areas: critical K from chevron­notched specimens compared with K stress K, and compliance analysis; and more.

Submit 200-word abstracts to J.H. Under­wood, Army Armament R&D Command, Benet Lab, Watervliet, New York 12189; telephone (518) 266-4183.

Coating Protection of Steel Structures

Abstracts are due by July 15, 1982 for the Symposium on New Concepts for Coating Pro­tection of Steel Structures, sponsored by American Society for Testing and Materials, January 26,1983, Lake Buena Vista, Florida.

Submit 300- to 500-word abstracts to R. F. Wint, Hercules Incorporated, 910 Market Street, Wilmington, Delaware 19899; tele­phone (302) 575-6091.

(continued on page 53)

49