RI bureau of mines 6

report of investigations 6497

By Wesley T. Holmes II and Lloyd H. Banning

ELECTRIC SMELTING OF TITANIFEROUS

IRON ORES FROM ALASKA,

MONTANA, AND WYOMING

1

I

UNITED STATES DEPARTMENT OF THE INTERIOR

BUREAU OF MINES

1964

---
ELECTRIC SMELTING OF TITANIFEROUS

IRON ORES FROM ALASKA,

MONTANA, AND WYOMING

By Wesley T. Holmes II and Lloyd H. Banning

4+ 4 * 4 * * + * 4 * report of investigations 6497

UNITED STATES DEPARTMENT OF THE INTERIOR

Stewart L. Udall, Secretary

BUREAU OF MINES

Marling J. Ankeny, Director

The work on Wyoming titaniferous iron ore was done under a cooperative agreement between the Bureau of Mines,

U.S. Department of the Interior, and the General Services Administration.
This publication has been cataloged as follows:

Holmes, Wesley T

Electric smelting of titaniferous iron ores from Alaska, Montana, and Wyoming, by Wesley T. Holmes II, and Lloyd H.

Banning. [Washington] U. S. Dept. of the Interior, Bureau of

Mines [1964]

23 p. illus., tables. (U. S. Bureau of Mines. Report of investigations 6497)

Based on work done in cooperation with the General Services

Admini stration.

1. Iron-Electrometallurgy. 2. Iron ores-Alaska. 3. Iron oresMontana. 4. Iron ores-Wyoming. I. Banning, Lloyd H., jt. auth.

II. Title. IlI. Title: Titaniferous iron ores. (Series)

TN23.U7 no. 6497 622.06173

U. S. Dept. of the Int. Library
CONTENTS

Page

Abstract ..................................................... .......

Introduction .............................................................

Acknowledgments... ......................

Description of titaniferous samples......................................

Beneficiation studies....................................................

Laboratory beneficiation tests on Choteau ore.......................

Pilot-plant, wet-magnetic separation tests..........................

Klukwan composite concentrate ..................................

Choteau pilot-plant concentrate ..............................

Electric smelting tests................... ................................

Experimental techniques and equipment..............................

Production of titania slag and pig iron.............................

Klukwan concentrate............................................

Choteau concentrate............................................

Iron Mountain massive ore .....................................

Evaluation of titania slags.....................................

Production of pig iron..............................................

Klukwan concentrates...........................................

Snettisham concentrate.........................................

Choteau materials..............................................

Evaluation tests on Choteau pig iron.....................................

Conclusions ..............................................................

ILLUSTRATIONS

Fig.

1

1

4

4

5

6

6

7

7

9

9

12

12

12

14

14

15

15

17

18

19

23

1.

2.

3.

4.

Effects of the fineness of grind on the iron and titania contents...

Pilot-plant flowsheet.... ................. ..........................

Smelting flowsheet..................................................

Carbon-Brinell hardness curve......................................

7

9

11

20

TABLES

1. Chemical analyses of titaniferous samples, percent..................

2. Results of laboratory beneficiation tests on Choteau ore...........

3. Average size distribution of Choteau material .......................

4. Choteau pilot-plant beneficiation test results......................

5. Chemical analyses of iron concentrates and ores used in smelting

tests, percent ............ .......................................

6. Chemical analyses of fluxes and reductants used in smelting tests,

percent.............................................................

7. Summary of data on production of titania slag and pig iron..........

8. Analyses of titania slags and pig iron, percent.....................

9. Actual and theoretical titania slag analyses, percent..................

10. Summary of data on production of pig iron...........................

5

6

8

8

10

10

13

14

15

16
ii

TABLES--Continued

Page

11. Analyses of products produced in pig iron smelting tests, percent... 17

12. Analyses of periodic samples of test 9 on Choteau crude ore ......... 18

13. Results of oxygen-blowing tests ..................................... 20

14. Summary of data on Choteau steelmaking tests ........................ 21

15. Analyses of pig iron and carbon steel, percent ..................... 21

16. Mechanical properties of carbon steel test specimens ................ 22
ELECTRIC SMELTING OF TITANIFEROUS IRON ORES

FROM ALASKA, MONTANA, AND WYOMING

by

Wesley T. Holmes I

1 and Lloyd H. Banning 2

ABSTRACT

Electric-smelting studies were made on titaniferous materials obtained

from the Klukwan and Snettisham, Alaska; Choteau, Mont.; and Iron Mountain,

Wyo., deposits with the objective of determining the feasibility of producing

pig iron and an enriched titania slag in one test series and pig iron alone in

another test series. In addition, related studies were conducted to determine

the amenability of Choteau crude ore to wet-magnetic separation and to determine the quality of steel that could be produced from the titaniferous pig

iron.

The continuous smelting tests were made in a three-phase, submerged-arc,

electric furnace, and the laboratory steelmaking tests were made in a singlephase electric-arc furnace. A continuous, belt-type, wet-magnetic separator

was used in conjunction with a ball mill and a spiral classifier in recovering

titaniferous magnetite from the crude Choteau ore.

Pig irons containing less than 0.05 percent phosphorus or sulfur were

readily produced from the titaniferous materials; iron recoveries ranged from

92 to 98 percent. The Choteau ore was ground to minus 65-mesh to produce a

concentrate containing 60 percent or more iron. The steel produced from the

titaniferous pig iron was a high-quality product.

INTRODUCTION

To obtain information that might encourage development of domestic titaniferous iron ore resources, the Bureau conducted: (1) Laboratory and pilotplant-scale wet-magnetic beneficiation studies on samples from Alaska and

Montana; the pilot-plant tests were made to produce concentrates for electricsmelting tests; (2) continuous smelting tests on crude ores and concentrates

1 Research chemist (inorganic), Albany Metallurgy Research Center, Bureau of

Mines, Albany, Oreg.

2 Supervising research extractive metallurgist, Albany Metallurgy Research

Center, Bureau of Mines, Albany, Oreg.

Work on manuscript completed February 1964.
2

of titaniferous magnetites with the objective of producing pig iron and high

titania slag or pig iron only; and (3) laboratory-scale oxygen-blowing and

steelmaking tests on titaniferous pig iron.

The Bureau of Mines program for developing mineral resources includes a

study of methods for utilizing domestic titaniferous iron-bearing materials.

Several potentially valuable titaniferous iron ore deposits, containing several million tons of ore each,are known in the United States; those in the

Pacific Northwest include the Klukwan, Alaska, deposit which is situated near

the Chilkat River and is about 23 miles by paved highway from the port of

Haines; the Snettisham deposit which is about 30 miles southeast of Juneau,

Alaska, on the margin of a deep-water harbor; the Choteau deposit which lies

about 9 miles north of Choteau, Mont., by U.S. Highway 89 and is within 1-1⁄2

miles of the great Northern Railway branch line; and the Iron Mountain deposit

which by road is 40 miles northeast of Laramie, Wyo., and is 9 miles northwest

of the Farthing Station of the Chicago, Burlington, and Quincy Railroad.

The electric-furnace smelting method was chosen for this investigation.

Iron ore blends containing more than 2 percent titania are not normally used

in the blast furnaces because (1) slags produced may have pasty characteristics which will cause irregular furnace operation; (2) character of the hot

metal may be adversely affected, resulting in excessive skulling of hot-metal

ladles; and (3) titanium exhibits a slight tendency to combine with carbon and

nitrogen to form an infusible titanium cyano-nitride which accumulates on furnace hearth and side wall.

The electric-furnace smelting tests were conducted under the direction of

project leaders on a three-shift-per-day basis. The continuous three-phase,

submerged-arc, electric furnace was usually operated by a three-man crew under

the immediate supervision of a pilot-plant foreman. The pilot-plant, wetmagnetic separation tests were also conducted on a three-shift-per-day basis,

but the laboratory beneficiation tests and the steelmaking tests were made on

day shift only.

Electric pig iron smelting is well established in several European countries and in Japan, and electric-smelting techniques have been described by

Collin4 and others. Results of prior electric-smelting investigations have

been published on the Wyoming titaniferous magnetite.5 Back and coworkers

3 Rossi, Auguste J. Titaniferous Ores in the Blast Furnace. Trans. AIME, v.

21, 1892-1893, pp. 832-867.

United States Steel Corp. The Making, Shaping, and Treating of Steel.

Pittsburgh, Pa., 1957, 7th ed., p. 253.

4 Collin, F. C., and 0. A. Grytting. A New Approach in Electric Pig Iron

Smelting. J. Metals, v. 8, No. 10, October 1956, pp. 1464-1468.

SBack, A. E., C. J. Chindgren, and R. G. Peterson. Treatment of Titaniferous

Magnetite From Iron Mountain, Wyo. BuMines Rept. of Inv. 4902, 1952,

15 pp.

Fuller, H. C., and V. E. Edlund. Electric Smelting Titaniferous Magnetite

Ore, Iron Mountain, Wyo. BuMines Rept. of Inv. 5776, 1961, 11 pp.
3

roasted the ore with sodium carbonate to convert the vanadium to a watersoluble form. After leaching the vanadium from the calcine, the leached

calcine was briquetted and smelted in an electric-arc furnace. About 90

percent of the iron was recovered as pig iron, and substantially all of the

titanium was recovered in the slag, which contained about 60 percent TiO , .

The smelting tests were made in a batch-type furnace using a maximum charge

of 100 pounds per test. The leached calcine charged to the furnace contained

about 46 percent iron; approximately 4,100 kilowatt-hours of electrical energy

was required per ton of pig iron produced. Fuller and Edlund conducted

induction-furnace smelting tests and electric-arc furnace smelting tests on

minus 3/4-inch plus 10-mesh ore. In one continuous-type smelting test, the

ore was smelted at a rate of 35 pounds per hour; coal was used as the reductant, and limestone was used as flux. The electrical energy consumption was

4,628 kilowatt-hours per ton of pig iron produced; 90.5 percent of the iron

was recovered. The authors concluded that in smelting titaniferous ore, overreduction must be avoided, otherwise, a thick viscous slag would result.

The objective of the smelting tests on Wyoming titaniferous magnetite at

the Albany Metallurgy Research Center was to produce pig iron and a hightitania slag suitable for chlorination. No flux was used in the furnace

charge, and a mixture of wood chips and coke was used for the reductant. The

tests were made on ore crushed to minus i inch, and the fines were not separated from the coarser ore prior to charging it to the furnace. The furnace

was charged at the rate of about 700 pounds per hour. Tapping temperatures

were slightly above 1,600° C. The slags contained from 65 to 67 percent TiO2,

and they were tapped from the furnace without difficulty. In one 88-hour test,

the electrical energy consumption was 3,822 kilowatt-hours per ton of pig iron

produced; 97.5 percent of the iron was recovered in the pig iron, and 98.5

percent of the TiO2 was recovered in the slag.

Results of laboratory-scale beneficiation tests on samples of Choteau

ore, containing 43.7 percent iron and 7.2 percent titania, were reported by

Wimmler.6 The ore was treated by a sink-float concentration method to yield

a minus 100-mesh concentrate containing 60.6 percent iron and 6.6 percent

titania with a recovery of 81.6 percent iron. Wet-magnetic separation of

minus 100-mesh ore resulted in a concentrate containing 59.3 percent iron and

5.7 percent titania, with an iron recovery of 83.1 percent. Treatment of

minus 100-mesh hydrogen-reduced material yielded a concentrate containing 59.4

percent iron and 6.4 percent titania, with an iron recovery of 88.5 percent.

Detailed laboratory-scale beneficiation studies on samples of Choteau ore

at the Albany Metallurgy Research Center showed that treatment of 65-mesh ore

rather than minus 100-mesh ore by wet-magnetic separation would yield a concentrate containing 60.2 percent iron with an iron recovery of 83.9 percent.

A p ot-plant-scale test substantiated data obtained in the laboratory.

sWimmler, N. L. Exploration of Choteau Titaniferous Magnetite Deposit, Teton

County, Mont. BuMines Rept. of Inv. 3981, 1946, 12 pp.
4

Thorne and Wells7 investigated the amenability of the Klukwan and

Snettisham ores to concentration. Their investigations showed that high-grade

concentrates with good iron recoveries could be attained. However, an appreciable percentage of titania remained in the magnetic concentrate and the iron

recoveries in the concentrates depended upon the grade of sample treated.

ACKNOWLEDGMENTS

Smelting studies on the Wyoming titaniferous magnetite were conducted

under a working fund agreement with the General Services Administration to

determine the amenability of domestic ilmenites and high-grade titaniferous

iron ores for producing both pig iron and an enriched titania slag suitable

for chlorination. The smelting studies on the Wyoming ore are included in

this report, because it was the only sample of the several titaniferous samples smelted under the contract that might be of commercial value for its iron

content only. The Bureau wishes to thank the General Services Administration

for the financial assistance given and the Union Pacific Railway Co. for

mining, loading, and shipping the sample to Portland, Oreg., without cost to

the Government.

DESCRIPTION OF TITANIFEROUS SAMPLES

Five samples from the Klukwan, Alaska, deposit and one sample each from

Snettisham, Alaska; Choteau, Mont., and Iron Mountain, Wyo., deposits were

procured for this investigation. Samples from Alaska were in the form of wetand dry-magnetic concentrates (wet and dry refer to production methods) and

hand-picked lump ore; the samples of Montana and Wyoming were shipped as

mined. Chemical analyses of the samples beneficiated at Albany are given in

table 1, and chemical analyses of those smelted directly are given in the

section on electric smelting tests.

Two shipments of Klukwan, Alaska, titaniferous material were received.

Initially, a 15-ton sample of wet-magnetic concentrate that had been produced

in a pilot mill run on several samples of material from the Klukwan iron

deposit was obtained from the Bureau of Mines, Mineral Resource Office, at

Juneau, Alaska. This concentrate had been prepared by a method described by

Wells and Thorne.8 Petrographic examination of the sample revealed that it

was essentially magnetite with relatively small quantities of hornblende,

augite, and epidote and very small to trace quantities of sphene, clinozosite,

and apatite. The only discrete titanium mineral observed was sphene, a calcium silicate mineral containing approximately 41 percent TiO2 . Since this

concentrate was consumed before the smelting investigation was completed, an

additional shipment of the material was procured. It consisted of handpicked

lump ore and crude concentrate. The lump ore was divided into two lots and

contained pieces up to 3 inches in diameter. Lot 1 weighed 5.7 tons, and lot

2 weighed 1 ton. Some ore, taken from the alluvial fan of the deposit, was

7Thorne, R. L., and R. R. Wells. Studies of the Snettisham Magnetite Deposit,

Southeastern Alaska. BuMines Rept. of Inv. 5195, 1956, 41 pp.

Wells, R. R., and R. L. Thorne. Concentration of Klukwan, Alaska, Magnetite

Ore. BuMines Rept. of Inv. 4984, 1953, 15 pp.

8 Work cited in footnote 7.
5

beneficiated in the field using a permanent-magnet-pulley belt separator. The

concentrate also was divided into two lots. One lot was designated crude concentrate A and weighed 3.2 tons; the other lot was designated crude concentrate B and weighed 10.9 tons.

TABLE 1. - Chemical analyses of titaniferous samples, percent

Fe Al 03 SiO2 CaO MgO TiO Mn V S P

Klukwan:

Handpicked lump, lot 1.. 40.1 9.80 18.8 2.55 5.43 3.16 0.34 0.14 0.03 0.11

Handpicked lump, lot 2.. 36.6 5.70 23.2 6.40 6.95 2.88 .22 .14 .04 .10

Crude concentrate A..... 35.0 6.30 25.6 8.98 6.08 1.79 .10 .13 .03 .10

Crude concentrate B..... 29.0 6.90 30.5 8.93 6.45 1.84 .13 .11 .03 .10

Choteau:

Crude lump ore .......... 54.1 3.16 10.1 2.70 1.68 6.52 .42 .17 .01 .10

About 3.5 tons of Snettisham, Alaska, magnetic concentrate was received.

This concentrate had been prepared at the Juneau station of the Bureau by a

method which was described by Thorne and Wells.9

The 49-ton carload of Choteau, Mont., ore was procured from two trenches.

One trench was located at N1⁄2NE3⁄4NW3⁄4 sec 13, T 25 N, R 6 W; the other trench was

located at SE1⁄4NE3⁄4 sec 13, T 25 N, R 6 W. After the Choteau ore was received

at the Albany Metallurgy Research Center, it was crushed to minus i-inch and a

sample for laboratory beneficiation tests was split from the bulk of the material by an automatic sampler. A petrographic examination revealed that the

ore consisted of magnetite (titaniferous to a minor degree), some calcite, and

quartz. Very small amounts of ferromagnesium minerals, ilmenite, chlorite,

chromite, fluorite, zircon, and garnet also were present. The minor amount of

ilmenite found in the sample was closely associated with the titaniferous

magnetite.

The 40 tons of massive Iron Mountain ore was taken from trench 6 located

at N1⁄2SEk sec 27, T 19 N, R 71 W in Albany County, Wyo. This ore was crushed

to minus 1⁄2 inch for smelting. A petrographic examination of a representative

sample revealed that the ore consisted of about 87 percent titaniferous magnetite and 10 percent ilmenite. Small amounts of spinel, limonite, chlorite,

and ferromagnesium silicate minerals also were present in the ore.

BENEFICIATION STUDIES

Beneficiation studies were directed toward the production of a high-grade

concentrate for electric-smelting tests. Because the principal iron-bearing

mineral of the ores was titaniferous magnetite, beneficiation studies on the

Kluhwan and Choteau materials were limited to wet-magnetic separation tests.

9 Work cited in footnote 7.
_ __._  ______ _ .

6

Laboratory Beneficiation Tests on Choteau Ore

Laboratory beneficiation tests were made to determine the effect of fineness of grind on iron recovery and grade of concentrate. A 72-pound sample

was divided into eight equal fractions. These fractions were stage-ground in

a small ball mill to pass 20-, 35-, 65-, 80-, 100-, 150-, 200-, and 325-mesh

screens, respectively. Tyler standard screen-scale sieves were used. Concentration tests were then conducted on kilogram-size samples of all ground fractions. A sample was placed in a large Pyrex container, 2,000 milliliter of

water was added, and the mixture was slurried by using a motor-driven stirrer.

Then, a 250-milliliter beaker containing a permanent magnet was lowered into

the slurry to collect the magnetite on its bottom surface. The beaker with

the adhering magnetite was removed from the slurry, and the magnetite was

deposited into another container by raising the magnet from the beaker bottom.

The beaker was repeatedly immersed in the slurry until no material collected

on the bottom surface of the beaker. The next step consisted of reconcentrating the magnetic fraction according to the same procedure to obtain a product

similar to that which would be expected in a continuous operation. A summary

of the data are given in table 2.

TABLE 2. - Results of laboratory beneficiation tests on Choteau ore

____Concentrates

Mesh' Weight- - Anal ses, percent2 _ Fe recovery,

percent Fe Al2 0o SiO2 CaO MgO TiO, Mn V S P percent

20 83.7 56.4 2.83 9.07 1.97 1.16 6.07 0.35 0.16 0.04 0.08 87.3

35 77.7 58.5 2.49 7.44 1.35 .91 6.13 - - - - 84.1

65 75.4 60.2 2.09 6.00 1.09 .62 6.19 .29 .15 .04 .10 83.9

80 74.9 60.1 2.15 6.22 1.00 .70 6.26 - - - - 83.2

100 73.7 60.6 1.99 5.71 .95 .49 6.30 - - - - 82.5

150 73.2 60.6 2.05 5.53 1.00 .47 6.28 .28 .17 .04 .12 82.0

200 72.1 59.9 2.33 6.03 1.29 .66 6.11 - - - - 79.8

325 71.6 59.7 2.41 6.15 1.07 .75 6.21 .31 .23 .02 .10 79.0

'lre was stage-ground to pass the screen of the indicated mesh.

2 A dash indicates no determination was made.

Test results showed that (1) the grade of concentrate improved with fineness of grind up to minus 100-mesh; (2) fine grinding did not completely liberate the titania from the iron; (3) there was little improvement in grade of

concentrate by grinding finer than minus 65-mesh; and (4) iron recovery

decreased with increase in fineness of grinding. Figure 1 shows the effects

of fineness of grind on iron recovery and on the iron and titania content of

the concentrates.

Pilot-Plant, Wet-Magnetic Separation Tests

To produce adequate quantities of concentrates for continuous smelting

studies on the Klukwan lump ore lots 1 and 2, the Klukwan crude concentrates

A and B, and the Choteau ore, each sample was ground in a ball mill and was

magnetically concentrated.
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LJ

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7

Klukwan Composite Concentrate

Concentrates were produced from lots 1 and 2 lump

ore and from A and B crude

concentrates by a technique

similar to that described by

Wells and Thorne.l 0 The concentrates were composited for

smelting; the composite sample

contained 57.8 percent iron.

Choteau Pilot-Plant

Concentrate

In this test the minus

1/2-inch ore was transferred

from a bin by an automatic

feeder to a 3- by 3-foot ball

mill that was in closed circuit with a 12-inch spiral

classifier. Overflow from the

classifier was pumped to a 12-

inch, belt-type, wet-magnetic

separator. The concentrate

was collected in barrels and

the tailings were pumped to a

waste pond. Figure 2 shows

the pilot-plant flowsheet.

mesh size

FIGURE 1.- Effects of the Fineness of Grind

on the Iron and Titania Contents

of Choteau Concentrates.

To determine flow rates, samples were taken of the crude starting material, the ball mill discharge, the classifier overflow, the final concentrate,

and the tailing; at 30-minute intervals, the entire stream of each product was

collected for 15 seconds. The samples of each product collected during each

8-hour period were composited. After each composite product was filtered,

dried, and weighed, a portion was used for determining size distribution

(table 3).

The pilot-plant test results are shown in table 4. The iron content of

the concentrate and the iron recovery were 0.3 and 0.9 percent higher, respectively, than the iron content of the concentrate and iron recovery from the

laboratory 65-mesh beneficiation test. The steel ball consumption was 11

pounds per net ton of ore ground. In grinding to 99 percent minus 65-mesh,

1.32 tons of crude ore was required to produce a net ton of concentrate containing 60.5 percent iron with an iron recovery of 84.8 percent.

'°Work cited in footnote 7.
8

TABLE 3. - Average size distribution of Choteau material

_Weight, percent1

Sieve size, mesh Material to Classifier Concentrate Tails

ball mill overflow

Minus 3 plus 4................. 12.3 - -

Minus 4 plus 6................. 8.5 - -

Minus 6 plus 10................ 9.8 - - -

Minus 10 plus 14............... 2.7 - - -

Minus 14 plus 20............... 2.0 - - -

Minus 20 plus 35............... 3.6 - - -

Minus 35 plus 65............... 3.1 1.0 0.1 0.9

Minus 65 plus 100.............. 3.2 59.4 69.9 35.8

Minus 100 plus 150............. 3.3 15.4 13.8 15.9

Minus 150 plus 200............. 3.0 12.5 11.3 16.8

Minus 200 plus 325............. 3.2 9.4 4.1 12.1

Minus 325 ....................... 2.4 2.3 .8 18.5

1 A dash indicates none.

TABLE 4. - Choteau pilot-plant beneficiation test results

Feed:

Quantity, net tons...............................................

Fe content, pct.......................................

TiO2 content, pct................................................

Feed rate, lb/hr...................................................

Ball mill:

Ball load, lb....................................................

Discharge, sp gr .................................................

Ball consumption per net ton of ore ground, lb.....................

Classifier overflow:

Specific gravity.................................................

Minus 100-mesh, pct............................................

Circulating load:

Moisture, pct....................................................

Dry weight, lb/hr................................................

Fe, dry basis, pct..............................................

Concentrate:

Fe content, pct..................................................

TiOC content, pct ................................................

SiO2 content, pct................................................

Tailings:

Fe content, pct... ...... ....... ............................

TiOQ content, pct.................. .............................

Recovery:

Fe, pct ..........................................................

Ti , pct ........................................................

30.1

54.1

6.52

690-860

1,800

1.90-1.95

11

1.27-1.32

39.6

15.5-17.2

995-1,290

57.1

60.5

6.10

6.28

25.1

7.71

84.4

71.0
9

Minus 1/2 -inch ore

ELECTRIC SMELTING TESTS

The objective of one smelting test

each on Klukwan and Choteau concentrates

and of two tests on massive Iron Mountain

ore was to produce high-titania slag and

pig iron. The objective of three smelting

tests on Klukwan concentrates and of one

test each on Snettisham concentrate,

Choteau concentrate, and Choteau crude ore

was to produce pig iron only. Potentially

valuable slag was produced only in tests

on Iron Mountain ore. Metal compositions

were within specifications for foundry and

low-phosphorus pig irons. Analyses of

iron concentrates and ores used in the

tests are given in table 5, and analyses

of fluxes are given in table 6.

Experimental Techniaues and Equipment

te

Two types of furnace charges were

used, those without flux and those with

flux. No flux was used in furnace charges

in which attempts were made to produce

high-titania slag. The ratio of carbon

from wood chips or hogged fuel to that

from coke was varied to control the

tapping temperature. By increasing the

proportion of wood chips in the furnace

charge, a higher tapping temperature was

obtained. Calculation of the reductant

requirement for both types of charges was

based on the iron oxide content of the

starting materials and the fixed carbon

content of the reductants. The stoiTo waste Storage barrels

FIGURE 2. - Pilot-Plant Flowsheet.

chiometric proportion of carbon, as shown in the tables, is defined as the

ratio of the actual weight of carbon used to the theoretical quantity required

for the reduction of the iron oxides to metal with the formation of CO in the

reduction reaction. Because some carbon entered the metal and some was consumed by air oxidation, more than the stoichiometric quantity was used in all

tests.

Except for one test, limestone was used in all tests in which flux was

added; in that one test silica was used. Slag basicities were calculated as

the mole ratio of CaO plus MgO to SiO2. In estimating flux requirements,
10

liquidus data by Osborn and coworkersl l and phase diagrams for ceramists by Lenin

and coworkers1 2 were used as a guide.

TABLE 5. - Chemical analyses of iron concentrates and ores

used in smelting tests, percent

Constituents1

Fe A12 03 SiOQ CaO MgO TiO2 Mn Cr V S P

Klukwan concentrate:

Test 1 head sample.... 62.7 2.00 5.21 2.16 1.88 1.52 - - 0.27 0.02 0.06

Test 5 head sample.... 62.3 2.00 5.05 2.32 1.30 .67 0.10 - .24 - -

Composite ............. 57.8 3.80 6.40 2.85 2.45 1.68 .20 - .31 .05 .10

Snettisham concentrate.. 61.6 3.20 7.10 1.55 .55 1.35 .36 - .31 .02 .07

Choteau:

Ore.................. 54.1 3.16 10.1 2.70 1.68 6.52 .42 0.22 .17 .01 .10

Concentrate........... 60.5 1.87 6.28 .89 .47 6.10 .25 .11 .15 .02 .06

Iron Mountain ore....... 50.0 5.60 .70 .26 3.40 22.5 .19 - .34 - .02

1A dash indicates no determination was made.

TABLE 6. - Chemical analyses of fluxes and reductants

used in smelting tests, percent

Constituents

Fe Al 03 SiO2 CaO MgO TiO2 Mn Cr V S P Fixed

carbon

Fluxes:

Pebble lime.... 0.26 0.88 0.88 94.0 0.29 0.01 0.05 - - - -

Limestone...... 1.66 .29 1.51 53.0 .61 .32 .03 - - - -

Silica (quartz) - 1.96 95.9 .32 1.14 - - - - 0.01 -

Reductants:

Coke........... .40 3.15 3.20 3.08 .45 .06 - - - .10 0.03 81.0

Coal, Utah..... .74 1.05 4.65 1.80 .30 .02 - - - .46 .03 49.5

Coal, Montana.. .65 2.88 3.29 1.72 .23 .08 - - - .34 .01 55.0

2 13.0

Hogged fuel.... . .20 .40 .28 .09 .10 .05 - 0.01 .01 .01 315.3

416.3

13.5

Wood chips..... .42 .23 .45 .41 .14 .23 .08 0.10 .01 .01 .01 619.7

7_22.0

'A dash indicates no determination was made. 2 Fixed carbon content of hogged fuel used in tests 1 and 5. 3 Fixed carbon content of hogged fuel used in tests 6 and 7. 4 Fixed carbon content of hogged fuel used in test 8. 5 Fixed carbon content of wood chips used in test 9. 6 Fixed carbon content of wood chips used in tests 2 and 10. 7 Fixed carbon content of wood chips used in tests 3 and 4.

"Osborn, E. F., R. C. Devries, K. H. Gee, and H. M. Kramer. Optimum Composition of

Blast Furnace Slag as Deducted From Liquidus Data for the Quaternary Systems

CaO-MgO-Al 2 0 3 -SiO . Trans. AIME, v. 200, 1954, pp. 33-45.

lLenin, E. M., H. F. McMurdie, and F. P. Hall. Phase Diagrams for Ceramists. Am.

Ceram. Soc. Inc., 1956, pp. 152, 170-173, 180-181, and 186.
Titaniferous

material

Mixer

Pigs Moldsa Meta

11

The tests were conducted in a three-phase, open-top, electric-arc smelting furnace. The steel shells of the furnace were lined with either magnesite

or carbon key brick; for most of the tests, shells having diameters of 30 and

40 inches inside the lining were used. The bottoms were covered with four

layers of 9-inch straight brick overlaid with 3 inches of the corresponding

refractory material. The inside depth of the furnaces was 40 inches. The

4-inch graphite electrodes were held by cable-suspended, water-cooled, clamparm assemblies and were spaced in an equilateral triangle pattern. Each electrode was about 9 inches from the furnace center. The vertical movements of

the electrodes were controlled automatically. The furnace was equipped with

two tap holes; the higher one was used to withdraw slag, and the lower one was

used to withdraw metal.

The general procedure for handling the materials was similar in all

tests. Figure 3 is the flowsheet of the smelting operation. Charge components were weighed, were mixed in a 6-cubic-foot cement mixer, were hoisted to

Flux Reductant

If

VVV

5

shell

'g

FIGURE 3. - Smelting Flowsheet.
12

the charging deck in a "tote" box by a 3-ton overhead crane, and then were

dumped on shoveling plates located adjacent to either side of the furnace.

Smelting was started on a preheated hearth; the charge was fed manually. A

dry-top, submerged-arc smelting technique was used; that is, a layer of unfused

charge was maintained over the molten pool at all times, and a high enough

voltage was used to prevent the electrode from dipping into the slag. Slag

and metal were tapped from the furnace at intervals of from 2 to 4 hours.

Normally, the tapholes were opened with an iron rod; however, when necessary,

an oxygen lance was used. Temperatures of the molten products were measured

with an optical pyrometer as they were tapped from the furnace. After tapping,

a mixture of crushed magnesite brick and periclase was used to close the tapholes. The slag was tapped into a cast-iron mold capable of holding approximately 1,000 pounds. Metal was drained from its taphole located approximately

3 inches below the slag taphole into a geared ladle. The molten metal was

poured from the ladle into cast-iron pig molds.

Production of Titania Slag and Pig Iron

The smelting furnaces were lined with magnesite refractories for all

tests. Data from smelting samples of Klukwan concentrate, Choteau concentrate,

and Iron Mountain massive ore are given in table 7, and analyses of metal and

slag test products are given in table 8.

Klukwan Concentrate

Part of the 15-ton concentrate sample from Juneau, Alaska, that had been

produced in a pilot mill run on several samples of material from the Klukwan

iron deposit was used in the initial smelting test. The assigned objective of

the test was to produce a slag as rich in titania as practical and to produce

pig iron. In an attempt to produce a slag of low SiO 2 content, a large excess

of reductant consisting of hogged fuel only was added to the furnace charge.

Satisfactory furnace operation was achieved; power was applied to the furnace

almost 98 percent of the time during the test period. About midway through

the test, however, the operators noted that the furnace bottom was receding.

The high tapping temperature, about 1,670° C most of the time, contributed to

the excessive corrosion of the magnesite refractories. Based on the analysis

of the furnace charge, the slag should have contained 19 percent MgO; it contained 32 percent. The TiO2 content of the slag was low--only 7.97 percent.

Test results indicated that a valuable high-titania slag could not be produced

from Klukwan concentrate; consequently, the objective of further tests on the

concentrate was to produce pig iron only.

Choteau Concentrate

Because the ratio of TiO2 to other slag-forming constituents of Choteau

titaniferous concentrate was much higher than that of Klukwan, an attempt

(test 2, table 7) was made to produce a potentially valuable slag. After 37

hours of furnace operation, the test was terminated because accretions had

formed on the furnace hearth, and it was difficult to open the tap holes.

Although the wood chip content of the furnace charge had been reduced below

that used in the test on the Klukwan concentrate, the power input had been
13

increased. These changes were not expected to effect as great a difference in

tapping temperature as that which occurred--a decrease from 1,670° to 1,500° C.

This large difference may be partly explained by the difference in the inside

diameter of the furnaces used. A higher tapping temperature would be expected

in the furnace having the smaller inside diameter. In the test on the Klukwan

concentrate, the diameter inside the refractory lining was 30 inches, and in

the test on the Choteau concentrate, it was 40 inches. Recent studies have

indicated that the liquidus temperature of the slag produced in smelting the

Choteau concentrate would be above 1,6000 C. Attempting to operate the furnace with a tapping temperature below the liquidus temperature of the slag

probably accounts for some of the difficulties experienced.

TABLE 7. - Summary of data on production of titania slag and pig iron 1

Material

Klukwan Choteau Iron Mountain

concentrate, concentrate, ore

test I test 2 Test 3 Test 4

Net operating time, hr............. 59 42.3 108.2 87.8

TiO2 content of material, pet...... 1.52 6.10 22.5 22.5

Charge additions per 100 pounds of

concentrate, dry basis, lb:

Coke ........ ..................... - - 7.0 8.5

Coal, Montana.................... - 7.5

Hogged fuel...................... 137 - - -

Wood chips....................... - 103 71.0 62.5

Moisture of hogged fuel or wood

chips average, pt ................ 36.4 23.5 56 60

Stoichiometric carbon, pet ......... 143 139 147 143

Electrical conditions, average:

Voltage, phase-to-phase.......... 118 106 120 115

Power input, kw................ 242 354 403 418

Tapping temperature, average ° C... 1,670 1,500 1,635 1,620

Products, lb:

Slag ............................. 1,548 2,423 13,789 12,250

Pig iron......................... 8,164 10,397 21,299 19,204

Kilowatt-hour consumption per net

ton of pig iron................... 3,400 2,879 4,095 3,822

Electrode consumption per ton of

pig iron, lb ...................... 48 39 46 45

TiC2 content of slag, pt .......... 7.97 40.4 64.5 67.4

Recovery, pet:

TiOQ in slag . . . . . . . . . . .. . . . . . . . . 65.4 90.4 93.1 98.5

Fe in metal ..................... 94.9 93.3 95.2 97.5

1 A dash indicates none.

ZBased on titania content in charge and in slag.

3 Based on iron content in charge and metal.
14

TABLE 8. - Analyses of titania slags and pig iron, percent'

Material

Klukwan, Choteau, Iron Mountain

test 1 test 2 Test 3 Test 4

Metal:

Fe ............................................ 90.6 93.1 95.8 94.5

C.................................... 4.7 3.01 3.25 3.73

Si................................... 2.91 2.24 .23 .25

Ti .................................... .49 .42 .12 .15

Mn ........................................... 18 .31 .04 .09

Cr ............................ ..... .... -. -

V.................................... . .41 .13 .04 .42

S.................................... .02 .03 .01 .01

P.................................... .06 .04 .01 .01

Slag:

TiQg ................................. 7.97 40.4 65.2 67.4

Fe ............ ...................... 4.8 4.10 4.1 2.4

Al Os . .. . . . . .. . . . . . .. . . . . . . . . .. . . . . . . 9.8 14.9 15.3 16.4

SiO . . .. . . . . .. . . . . . . .. . . . . . . .. . . . . . . . 26.0 25.2 2.89 2.91

CaO .......................................... 20.0 9.3 .22 .23

MgO.................................. 32.0 4.2 10.7 9.70

Mn ..-............ ................ - .17 .10 .10

Cr ......... ............. .17 - -

V................ ·...... ...-....--.. .12 .18 .11

'A dash indicates no determination was made.

Iron Mountain Massive Ore

The production of a high-grade titania slag and low-phosphorus pig iron

from massive iron ore was demonstrated in tests 3 and 4. The bulk of the carbon was supplied by wood chips, and the remainder was supplied by coke instead

of coal as used in test 2. Furnace operation was excellent throughout these

tests. Tapping temperatures exceeded 1,600° C. The electrical energy consumption was higher than in previous tests, and the metal products contained

a lower percentage of silicon. The iron recovery (97.5 percent) in the fourth

test was higher than in any previous test.

Evaluation of Titania Slags

Table 9 shows the actual chemical compositions of slags produced in the

smelting tests and the slag compositions that would have resulted from the

complete reduction of the iron oxide and 30 percent of the silica content. The

slag-forming constituents of the reductants were added to those of the titaniferous material in calculating the theoretical slag composition. Only the

slag produced from the Iron Mountain ore was comparable in titania content to

those produced commercially.l a The average TiO2 contents of the slags from

laKnoerr, A. W. World's Major Titanium Mine and Smelter Swing into Full-Scale

Production. Eng. and Min. Jour., v. 153, No. 3, March 1952, pp. 72-79.

Miller, Jesse A. Titanium: A Materials Survey. BUMines Inf. Circ. 7791,

1957, p. 127.
15

tests 3 and 4 (table 7) were 64.5 and 67.4 percent, respectively. However,

their alumina and magnesia contents were higher than the alumina and magnesia

contents of commercial products. If high-titania Iron Mountain slag were to

be produced commercially, its value for any particular use would need to be

established.

Under present conditions, the possibility of producing a valuable slag

from the Choteau ore is quite remote, and the low TiO2 content of the theoretical Klukwan slag precludes producing a commercial slag product from that

ore.

TABLE 9. - Actual and theoretical titania slag analyses, percent

Constituents

Fe A12 3 Si02 CaO MgO TiO2

Klukwan:

Actual (test 1).................. 4.8 9.8 26.0 20.0 32.0 7.97

Theoretical ..................... - 17.8 32.5 19.3 16.8 13.6

Choteau:

Actual (test 2) .................. 4.1 14.9 25.2 9.3 4.2 40.4

Theoretical'.................... - 14.9 31.3 9.2 4.0 40.6

Iron Mountain:

Actual (test 4) .................. 2.4 16.4 2.9 .23 9.7 67.4

Theoretical' .......... -........ - 17.8 2.6 2.3 10.4 66.9

'Assuming that all iron oxide and 30 percent of the silica content are reduced

to the elemental state.

Production of Pig Iron

Since the results of previous tests indicated that a potentially valuable

high-titania slag could not be produced from Klukwan or Choteau concentrates,

the objective of the tests given in this section was to attain a low electrical energy consumption consistent with a high-iron recovery in the production

of high-grade pig iron from titaniferous materials. The titania content of

the titaniferous magnetites was treated as another gangue constituent that was

to be rejected to the slag. Summary of test data and analyses of metal and

slag products are given in tables 10 and 11.

Klukwan Concentrates

One smelting test was made on a sample of the high-grade concentrate

obtained from the Juneau, Alaska, station, and the other two tests, tests 6

and 7, were conducted on the composite concentrate that was produced at the

Albany Metallurgy Research Center. A magnesite-lined furnace was used in all

tests.
16

TABLE 10. - Summary of data on production of pig iron1

Material

Klukwan Snettisham Choteau

co centrates concentrate, Ore Concentrate

... Test 5 Test 6 Test 7 test 8 Test 9 Test 10

Net operating time, hr......... 50.5 48.5 21.0 23.3 100 44

TiQC content of material, pet.. 0.67 1.68 1.68 1.35 6.52 6.10

Charge additions per 100 pounds

of material, dry basis, lb:

Silica ...................... - 3.5 - - - -

Pebble lime.................. . - - - - - 1

Limestone.................... 3. - 3 5 13 5

Coke ......................... 11.2 - -

Coal, Montana .................. - - 12.5 3.5

Coal, Utah .................... - 15.5 6 6.8 - -

Hogged fuel.................. 68 56 92 86 - -

Wood chips................... . - - - - 60 103

Moisture of hogged fuel or wood

chips, average, pct........... 40.0 40.0 39.6 34.1 36.0 17.5

Stoichiometric carbon, pet..... 120 98.4 102.7 98.7 130 128

Electrical conditions, av:

Voltage, phase-to-phase ...... 141 102 120 123 119 118

Power input, kw .............. 242 240 214 229 329 340

Tapping temperature, av o C.... 1,450 1,450 1,525 1,395 1,545 1,625

Products, lb:

Slag ......................... 2,339 2,400 1,120 1,303 11,388 3,600

Pig iron ..................... 10,517 7,184 3,997 4,330 17,683 10,450

Basicity of slag .. . ..... .. . ... 1.36 0.96 1.97 1.57 1.35 1.40

Kilowatt-hour consumption per

ton of pig iron............... 2,460 3,196 2,240 2,750 3,721 2,858

Electrode consumption per net

ton of pig iron, lb ........... 27 63 52 61 21 36

Iron recovery, pct3........... 97.3 95.0 96.7 92.4 96.9 96.1

'A dash indicates none.

2The basicity was calculated as the mole ratio of CaO + MgO

SiO0

3Based on iron content in charge and in metal.

Enough limestone was used in the charge of the initial test (test 5) of the

group to insure the production of a slag having a basicity of at least 1.0. About

36 percent of the carbon was obtained from coke, and the rest was obtained from

hogged fuel. No operating difficulties were noted. About 97 percent of the iron

charged to the furnace was recovered in the pig iron product.

In the sixth test, silica was added to the charge to yield a foundry pig iron

and a slag having a basicity of 0.96. About 47 percent of the carbon was supplied

by coal, and the remainder was supplied by hogged fuel. Forty-four hours after the

test was started, accretions had formed on the furnace hearth; feeding of the charge

was interrupted to smelt the crust of material from the delta zone and from the side

wall of the furnace. After the material became molten, the furnace was tapped and

the test was terminated. The iron recovery was lower than that of test 5, and the

electrical energy consumption was higher. A higher proportion of slag to pig iron

than in the previous test and the operating difficulties experienced were factors

that added to the electrical energy consumption.
17

TABLE 11. - Analyses of products produced in pig iron smelting tests, percent1

Material

_Klukwan Snettisham, __ Choteau

Test 5 Test 6 Test 7 test 8 Test 9 Test 10

Metal:

Fe ............... 92.6 91.7 91.5 94.8 93.4 93.2

C ................ 4.8 3.97 3.72 2.71 3.32 4.17

Si............... 3.51 3.13 2.23 .44 .88 .79

Ti............... .10 .26 .43 .42 .59 .52

Mn ............... .18 .29 .61 .40 .67 .39

Cr............... - - -- .34 .21

V ................ .32 .20 .60 .35 .26 .20

S ................ .02 .02 .02 .02 .03 .03

P ................ .06 .02 .01 .01 .03 .04

Slag:

Fe ............... 4.0 4.32 4.05 3.79 3.60 4.15

A12 03 . . . . . . . .. . . . 7.6 21.6 21.7 23.1 11.1 10.7

SiO . . . . . . .. . . .. . 36.0 36.5 24.3 27.6 29.6 25.4

CaO .............. 26.5 17.0 25.0 30.1 29.4 25.5

MgO.............. 13.8 11.4 14.1 7.41 5.74 5.5

TiO ............. 3.8 7.4 8.2 5.55 18.3 26.3

Mn ............... - - - - .44 .38

Cr............... - - - .21 .37

V .. .............. .46 .32 .63 .49 .06 .20

'A dash indicates no determination was made.

With some modification in operating procedure, test 7 followed test 6

without cooling off and cleaning out the furnace. Limestone was added to the

charge instead of silica. More of the total carbon was obtained from hogged

fuel than in the two previous tests. The test was characterized by excellent

furnace operation, and a fluid slag was produced. The pig iron recovered was

higher in manganese, titanium, and vanadium and 0.9 percent lower in silicon

content than the metal produced in test 6 under acid conditions. Also, the

electrical energy consumption was considerably lower.

Snettisham Concentrate

In the eighth test, limestone was used in the furnace charge to yield a

low-phosphorus pig iron and a slag with a basicity of 1.57. A lower proportion of carbon was used than in previous tests. The percentage of total carbon obtained from coal was about the same as that of test 7. No operating

difficulties were noted. About 92 percent of the iron was recovered in a

premium-grade pig iron. Carbon and silicon contents of the metal were lower

than in any of the tests on Klukwan concentrates. Electrode consumption was

high; the low proportion of carbon in the charge was one of the factors that

contributed to the high electrode consumption.

I
18

Choteau Materials

Smelting tests were made on both crude ore and concentrate.

was lined with carbon refractories for the test on the crude ore

magnesite refractories for the test on the magnetic concentrate.

The furnace

and with

Test 9 on Choteau crude ore was divided into four periods which varied

from 22 to 31 hours each. After preheating the furnace, a mixture of crude

ore, limestone, Montana coal, and wood chips was charged to the furnace. A

satisfactory furnace operation was achieved. The metal and slag from the

various periods were composited for sampling. Results of analyses, given in

table 12, on the composited samples from the various periods show that neither

the composition of the metal nor the

another.

slag varied greatly from one period to

TABLE 12. - Analyses of periodic samples of test 9

on Choteau crude ore

Composite of taps

1-11 12-22 23-33 34-45

Period, hr........... 25 22 28 31

Metal, pct:

C.................. 3.05 3.41 3.45 3.38

Si................. . 1.13 .69 .75 .71

Mn ................ .75 .56 .74 .69

Ti....... ........... .58 .62 .63 .53

Slag, pct:

Fe ................. 3.85 3.41 3.62 3.16

AlO2 . . . . . . . . . .. .. . 9 .1 6 1 0 .9 11 .2 1 1 .6

sio .............. 23.6 27.1 30.3 30.9

CaO ................ 29.8 31.4 30.5 30.0

MgO.................. 5.07 5.79 5.47 4.68

TiO ............... 19.4 18.6 18.9 17.5

The test on concentrate to produce pig iron only was a continuation of

the test conducted to produce a slag as high as possible in titania and pig

iron. During test 2, accretions of slag had gradually formed in the furnace

which caused termination of the test. Before starting this test, lime was

added to the furnace and reacted with the accretions on the furnace side walls.

The molten material which formed was tapped from the furnace. Only a small

quantity of CaO was required in the charge of this test to produce a fluid

slag; 5 pounds of limestone and 1 pound of CaO per 100 pounds of concentrate

was sufficient. As in the test on the crude ore, the bulk of the carbon was

supplied by wood chips; the remainder was supplied by 1/4-inch Montana coal.

No operating difficulties were experienced. After 39 hours of continuous

operation, however, corrosion of the furnace lining was observed. The accountability of the charged constituents in test products was satisfactory with the

exception of MgO. A materials balance indicated that the slag contained 75

percent more MgO than was in the furnace charge. The MgO from the furnace
19

lining, as well as the limestone added to the furnace charge, increased the

slag basicity to 1.35 compared with a basicity of 0.64 of the slag from test 2

in which the concentrate was smelted without flux addition. Furthermore, the

TiO2 content of the slag was 26 percent compared with 40.4 percent for the

slag of the previous test.

EVALUATION TESTS ON CHOTEAU PIG IRON

Laboratory tests were made to determine the feasibility of producing carbon steel from titaniferous pig iron. The pig iron chosen for these tests had

been produced from choteau ore and concentrate. Before the steelmaking tests

were initiated, the relationship between carbon content of the metal and its

hardness was established in oxygen blowing tests; this relationship was used

in adjusting the carbon content to the desired level in the steelmaking tests.

The single-phase, electric-arc furnace used in the oxygen-blowing and

steelmaking tests was equipped with two manually regulated 3-inch graphite

electrodes. The furnace shell was lined with magnesite; the inside diameter

was 24 inches. Molten material was discharged from the furnace through its

combination charging and decanting door by tilting the furnace with a geardriven mechanism.

In each oxygen blowing test, 150 pounds of pig iron together with limestone and quartz was placed on the hearth of the preheated furnace. In melting, the fluxes formed a cover slag for the metal. The molten bath was heated

until an immersion temperature reading of at least 1,680° C was attained, and

then it was blown with oxygen in 1-pound increments at a manifold pressure of

40 psi until a total of 8 pounds was used. The oxygen lance was a magnesiainsulated 1/4-inch iron pipe. After each 1-pound addition of oxygen, a control sample was taken by dipping a cast-iron spoon into the bath; then the

sample was deoxidized with aluminum before pouring it into an iron mold. The

sample which weighed about 1 pound was allowed to cool for about one-half

minute before quenching in water. The Brinell hardness of each sample was

determined. Slag samples also were taken after each oxygen addition by

dipping an iron rod into the bath. The test products were poured from the

furnace with no attempt being made to produce carbon steel upon completion of

the blowing.

Metal samples contained from 0.01 to 3.00 percent carbon. Test results

indicated that 1 pound of oxygen removed about 0.64 pound of carbon, provided

the initial carbon content of the bath exceeded 0.50 percent. Carbon analysis

and hardness of metal samples are given in table 13. Figure 4 shows the relationship between Brinell hardness and carbon content of the samples from 0.01

to 2.0 percent carbon. Results of tests on samples of higher carbon content

were not included on this graph because they were not of significance in the

steelmaking tests.
20

It II ' v -V

0Q

o')

7J

D

LI

Z

I

w

rr0

m

400

TABLE 13. - Results of oxygen-blowing tests

Test 1 Test 2 Test 3 Test 4

C, Brinell C, Brinell C, Brinell C, Brinell

per- hard- per- hard- per- hard- per- hardcent ness cent ness cent ness cent ness

Pig iron, head sample.... 3.45 653 3.33 653 3.23 627 3.05 601

After 02 addition of--

1 lb ................... 3.00 601 2.85 578 2.81 578 2.61 555

2 lb ................... 2.49 534 2.40 514 2.37 514 2.21 495

3 lb ................... 2.05 495 2.00 477 1.86 461 1.79 461

4 lb ................... 1.60 444 1.54 444 1.44 429 1.35 429

5 lb ................... 1.14 415 1.05 401 1.00 388 .92 388

6 lb ................... .63 341 .59 341 .57 331 .51 321

7 lb ................... .18 241 .14 223 .12 217 .06 197

8 lb................... <.01 143 <.01 143 <.01 143 <.01 143

Three steelmaking tests were made. The Choteau pig iron had been

remelted before its use in these tests in an attempt to produce a more uniform

head sample; the remelting had altered its composition. In each test, 150

pounds of the pig iron was placed on the preheated hearth of the furnace

together with lime and quartz. After melting the furnace charge and obtaining

a temperature of at least 1,680° C, the bath was blown with oxygen until the

R ff\

-

I I I I I I I II

0~~~~

300

I

200 /d

0

I non I I I I I I I I Jl ---- 'v0 0.4 0.8

CARBON,

1.2

percent

1.6 2.0

FIGURE 4. - Carbon-Brinell Hardness Curve.
21

I

carbon content of the metal was lowered to between 0.26 and 0.80 percent.

Holding the molten products in the furnace after oxygen blowing resulted in

further lowering the carbon content of the metal at the rate of 0.10 percent

every 10 minutes. Silicomanganese was added to the bath to stop the oxidation

reaction after the desired carbon content of the metal had been attained. The

meltdown slag was then decanted from the furnace, and a new slag was formed by

melting a mixture of lime and quartz. After attaining a temperature of

1,650° C, the bath was deoxidized with aluminum and the manganese content of

the bath was adjusted by adding electrolytic manganese. The molten products

were decanted from the furnace into a geared ladle, the slag was skimmed from

the metal, and the steel was poured into a 200-pound ingot mold at temperatures of 1,600° C and higher. Test data are given in table 14; analyses of

the pig iron charged to the furnace and of the steel produced are given in

table 15.

TABLE 14. - Summary of data on Choteau steelmaking tests

Test 1 Test 2 Test 3

Charge additions per 150 pounds pig iron:

Limestone, lb ............................ 1 10 10

Pebble lime, lb .......................... 5 5 5

Quartz, lb ............................... 4 3.5 3.5

Silicomanganese, lb.............................. 1 1 1

Initial slag:

Pouring temperature, ° C ................. 1,690 1,650 1,640

Weight, lb .............................. 19 25 25

Cover slag prior to deoxidation:

Pebble lime, lb .......................... 5 5 5

Quartz, lb......................................... 2 2 2

Aluminum, lb............................ ... 1 1 1

Electrolytic manganese, lb ................. 1 0.50 0.50

Pouring temperature, o C ................... 1,645 1,600 1,675

Final slag, lb............................. 13.5 13 14

Metal, lb .................................. 136 133 134.5

Iron recovery, pct ........................ 91.3 90.8 92.7

TABLE 15. - Analyses of pig iron and carbon steel, percent

-Fe C C1 h Si Ti Al Mn Cr V S P

Pig iron:

Test 1..... 97.5 1.66 0.26 0.34 0.08 - 0.12 - 0.15 0.02 0.04

Test 2....... 96.6 2.26 .63 .41 .05 - .19 - .13 .01 .05

Test 3..... 96.1 2.79 .66 .34 .09 - .20 - .16 .01 .03

Carbon steel:

Test 1..... 98.3 .35 - .10 .01 0.02 .68 0.09 .12 .01 .02

Test 2....... 99.0 .10 - .10 .01 .01 .29 .08 .13 .01 .03

Test 3....... 99.4 .06 .10 .01 .01 .08 .07 .11 .01 .03

1After oxygen addition.
22

Ingots produced in the first and second tests were solid throughout,

whereas the ingot produced in the third test contained blowholes. The highmagnesia content of the slag may be attributed to the dissolving of the

magnesia insulating material around the lancing pipe and the magnesite lining

while blowing the bath with oxygen.

Specimens for mechanical property evaluation were prepared from ingots of

the first and third steelmaking tests. Each ingot, weighing about 134 pounds,

was heated to 1,2600 C in a preheated furnace and held for 20 minutes before

hot-working. Then each ingot was forged to about 1-inch thickness. After

conditioning the metal by either grinding or machining to remove folds and

cracks, the slab was rolled into 1/4-inch sheet stock. The sheet stock was

annealed by reheating to 900° C for 10 minutes, and then it was air-cooled.

Next, the material was cleaned by grit blasting.

Six test specimens were prepared from each of the two sheets. Tensile

strength, yield strength, elongation, and hardness of test specimens are shown

in table 16. The tensile and yield strengths of test specimens were above

average for carbon steels; the small vanadium and chromium contents of the

specimens may have attributed to their strength.

TABLE 16. - Mechanical properties of carbon steel test specimens

Tensile Yield Elongation,

strength, strength, percent in Rockwell A

psi 0.2 percent 2 inches hardness

_____ offset, psi

Test 1

Specimen:

1............. 113,000 75,500 23 58

2............. 113,000 76,000 23 59

3............. 115,500 77,000 24 59

4............. 119,000 82,500 22 60

5 ............. 119,500 81,500 22 59

6 ............ 119,000 82,500 23 59

Average...... 116 500 79,000 23 59

Test 3

Specimen:

1............. 74,000 47,000 30 50

2 ............. 75,000 47,000 30 50

3 ............. 79,500 50,000 28 52

4 ............. 83,000 60,000 25 50

5 ............. 74,500 47,500 30 49

6 ............. 74.500 51,000 30 50

Average ...... 76 500 50.500 29 50
23

CONCLUSIONS

Continuous electric smelting tests have shown that various types of highgrade pig iron can be produced without serious operating difficulties from

Alaska, Montana, and Wyoming titaniferous magnetites which contain from 1.63

to 22.5 percent TiO2 . The test results indicated that fine-grained concentrate and crude ore can be smelted without flux, and a high-titania slag can

be produced provided enough bulky reductant, such as wood chips, is used in

the furnace charge and the furnace is operated at a high enough temperature.

Probably the only titaniferous magnetite that would be of potential value for

its TiO2 content is the Wyoming material.

Results of wet-magnetic separation tests on Choteau material indicate

that no significant increase in iron content or decrease in TiO2 content of

the concentrate could be attained by grinding finer than minus 65-mesh.

Steelmaking tests in a small electric furnace indicated that no unusual

problems would be encountered in producing steel of high quality from titaniferous pig irons. The test results indicated that the tensile and yield

strengths and the elongation of the test specimens were above average for

carbon steels.

INT..BU.OF MINES.GH. ,PA. 6977