ticularly amenable to an efficient small scale operation by a nonintegrated firm; uses scrap-the economical material for the nonintegrated producer-for about 98 percent of its metallic input; produces particularly high qualities of steel; and is particularly adaptable to specialization in stainless and high-alloy steels.

Electric induction and electric resistance furnaces, which are used for producing exotic alloys and some specialty steels, are of little quantitative importance, and need not be discussed in this report.

The cupola, the major type of furnace in the production of iron castings in the foundry industry (also used to a slight extent in the steel industry), which accounted for about 80 percent of the 15.3 million tons of iron castings in 1964, also has been increasing its scrap proportion of total metallic input in recent years to about 75 percent in 1963. About two-thirds of the scrap used in cupolas is cast iron; the rest is steel.

SMALL USE OF SCRAP IN BLAST
FURNACES

Blast furnaces traditionally have used a very low proportion of scrap to total metallic input, and this is not expected to change much in the next decade. The proportion was about 5 percent in 1963. Pig iron technically could be made from a 100-percent scrap charge, and capacity would be greatly increased by this practice. This is not done because the cost of the resultant pig iron would nevertheless be much higher than under present practice.

It is of great relevance to the demand for scrap that a large number of existing blast furnaces have increased their capacities between 50 percent and 100 percent since 1960 as a result of several technological improvements. These improvements include equipping blast furnaces for higher hot blast temperatures and for auxiliary fuel injections. They also include the development and increasing availability and use of agglomerated iron ores, which increase blast furnace productivity because of the higher iron content and more combustible structure of these materials. If these improvements were applied to all existing blast furnaces, the resultant capacity probably would be more than sufficient to meet the demand for pig iron and hot metal in 1975, even if no additional blast furnaces were installed.

DENSITY AND SIZE REQUIREMENTS
BY TYPE OF FURNACE

Requirements of the different ironmaking and steelmaking furnaces differ with respect to the size of units of scrap which will fit into the charging box, by means of which the scrap charge is introduced into the furnace. They also differ with respect to density requirements; that is, the proportionate relationship required between heavy, medium, and light scrap. The size requirements are readily met by the scrap processor, who has considerable control over the sizes in which he prepares the various types of scrap. However, smaller sizes carry somewhat higher prices. Hitherto, there appears to have been no problem in obtaining the appropriate density mix; especially since there is a considerable amount of flexibility among steel producers in using mixtures which deviate moderately from the optimum.

However, if shredded scrap-the product of relatively new and promising processes of turning out high quality, light, small pieces of scrap from automobile bodies and similar materials-should increase markedly in supply, as is likely, a question may be raised as to whether the increase in the light scrap proportion of the total scrap supply would be compatible with the density requirements of the various furnaces.

The maximum size of scrap usable in ironmaking and steelmaking is determined primarily by the size of opening through which the charge is introduced into the furnace and the method of loading (i.e., type of equipment) used. The blast furnace can accommodate only small pieces (up to about 1 foot in length) because scrap must enter the furnace through a small channel opening around the top of the shaft. Both the open hearth and old-fashioned electric furnaces have side doors through which scrap is introduced via charging boxes. For this type of operation scrap must be cut to charging box length, about 5 feet, so that it will be flat in the box. Large rejected ingots over 6 feet in length frequently are charged into open hearth furnaces.

The modern top charge electric furnace tends to use scrap of shorter lengths than the open hearth, although it can accommodate larger lengths. The BOF can use scrap, which enters the furnace through a box-chute, in sizes as large as the open hearth. For the cupola, individual pieces of iron and steel scrap must be sized so that no single

30-057 0 70 pt. 2 26

dimension exceeds one-third of the cupola diameter. Thus, scrap for a 72-inch (diameter) cupola should not exceed 24 inches in any dimension.

All steelmaking furnaces operate relatively more efficiently with a reasonably balanced mix of heavy, medium, and light scrap. The proper balance is different for different furnaces. Although the mix can be varied considerably, too great a departure presents problems. Too much heavy scrap takes longer to melt, requires more fuel, and, in the case of the electric furnace, offers less protection to the furnace roof from the intense heat. One great advantage of the heavy scrap is that it requires less charging time by eliminating or reducing the amount of back (repeat) charging per heat of steel, thereby decreasing production time and heat losses. Too much light scrap has the disadvantage of increasing metallic losses through oxidation, and of increasing the need for backcharging, particularly in the open hearth and electric furnaces. (Backcharging or introducing the charge in two or more installments increases with larger proportions of light, low-density scrap because there is not room enough in the furnace to introduce the full charge at one time; a partial charge must first be melted to make room for the next installment.)

It is difficult to be certain as to the preferred mixture ranges for the various furnaces. Reported actual usage may be quite different from what would be preferred, because of availability considerations. For instance, since home scrap is largely heavy, and companies try to use their own for cost reasons and its known quality, the proportion of heavy in the mix may be larger than preferred. The higher quality of heavy melting scrap as compared with No. 2 bundles also leads many companies to push the heavy melting proportion up beyond the optimum. In view of these considerations, as well as the high degree of ability to deviate from preferred mixtures, it is highly probable that a vastly increased level of production of shredded scrap will be compatible with the density requirements of steelmaking furnaces.

In using high-phosphorous pig iron, however, it may be desirable to use easily oxidizable scrap, as this builds up the FeO content of the slag, which facilitates the removal of phosphorous from the heat.

• Appendix table A-12 shows the amounts of the various types of scrap and pig iron used in August 1964 in a selected number of steel furnaces and cupolas, based on a special canvass.

TECHNICALLY FEASIBLE VARIATIONS

IN SCRAP PROPORTION

Previously introduced data on the scrap proportion of total metallics (ie., scrap plus pig iron) used in different iron and steel furnaces have described actual current practice. However, it is desirable to know to what an extent it is technically feasible to change the scrap proportion now in use. Table 1 shows for each major type of ironmaking and steelmaking furnace the current scrap proportion, and the maximum proportions which would be technically feasible. It also indicates the rela tive importance in steelmaking of each type of furnace.

Technically feasible as used here means that these proportions could be used without introducing intolerable technical problems. It ignores the fact that the use of higher proportions would undoubtedly tend to increase operating costs, particu larly as the proportion was pushed closer to the maximum. For instance, production time would tend to be increased; more fuel would be needed as scrap replaced hot metal; and backcharging might be needed more often.

As may be seen in the table, it would be technically feasible for steelmaking furnaces as a whole to use a scrap proportion approximately 70 percent larger than now. Hot metal using open hearths (integrated companies) could increase the proportion from the present nearly 40 percent to 80 percent; cold melt open hearths (nonintegrated companies), however, could not practically increase the current 80 percent proportion. The BOF proportion theoretically could increase from the present 28 percent to nearly 50 percent under present technology, and could be pushed up to 100 percent if certain technical changes were made (e.g., using oxygen-fuel lances), and if an all-scrap charge were compatible with the type of steel being made. Electric furnaces, of course, cannot increase their scrap proportion, since they already are using nearly 100 percent scrap in their furnace charge In the making of castings the cupola, already s high scrap user, could increase its proportion from 77 percent to 100 percent (this might require an increase in the proportion of cast iron scrap). As in steelmaking, electric furnaces used for castings production already are nearly 100 percent scrap

users.

1 Total metallics in this table includes only pig iron and scrap, except for pig tros production, for which the iron content of iron ore is included.

Although technically feasible, it will often be impractical to radically change customary scrap proportions, because steelmaking time is likely to be increased or particular specifications may be dimcult or impossible to met Estimates of maximum proportions are based on judgment of BDSA Industry specialists, based both on published materials and their ows experience.

Includes small amount of castings (about 178,000 tons) made by steel tagot producers

The maximum could literally be pushed to 100 percent scrap, but the got and quality control problems introduced would make it impractical. For cold melt shops, the 80 percent scrap proportion requires a substantial

As indicated above, the use of the maximum proportions technically feasible in steel furnaces would increase operating costs. However, if the scrap proportion were increased only part of the full amount which would be technically feasible, it is likely that the rise in operating costs would be minor. Publicly available cost information in this area is, unfortunately, virtually nonexistent.

Thus, there are no technical reasons that the usage of acceptable scrap could not be increased markedly, probably far beyond the available supply, present or potential. The actual scrap proportion used is far below its technically feasible maximum principally because less scrap becomes available each year than could be used. Although the scrap proportion would be somewhat higher if low-quality bundle-type scrap were fully acceptable, the proportion would continue to be far below the technically feasible rate. Price tends to be competitively set at a point that will equate the supply and demand for acceptable scrap. These economic considerations will be discussed more fully later in the study.

A note is called for on the blast furnace, which, although appearing in the table, presents a somewhat different case with respect to increased operating costs. The table shows that it would be technically feasible to increase the scrap proportion of blast furnaces from the present extreme low of 5 percent to a maximum of 100 percent. However, despite the techncial feasibility, the sub

79 804

109, 261

100.0

88,834

81.4

804

84,392

77.3

80

4,442

4.1

10,920

9.0

28

50 (or more)

8,544

7.8

10

20.

963

The maximum proportion would rise to about 60 percent if scrap were preheated to 1250°, and 100 percent if oxygen fuel lances were used. These techniques, however, have not yet been used commercially.

1 Total based on castings production only, but separate figures for cupola and electric and other include the noncastings production of these furnaces as well.

Castings output is measured by shipments rather than production figures. Most cupolas can use 100 percent scrap only if a substantial proportion of the scrap la cast iron.

Source: Business and Defense Services Administration.

stantially higher cost of scrap over iron ore precludes this from serious consideration, either now or in the foreseeable future."

LESS HOME SCRAP FROM
CONTINUOUS CASTING

The supply of home scrap will be substantially reduced by the new process known as continuous casting, which promises to grow rapidly in the future. It is estimated that 18.5 percent of new steel will be continuously cast by 1970 and 38.5 percent by 1975. Under present techniques, continuous casting cannot exceed about 50 percent of total steel produced, because certain types of steel cannot yet be continuously cast successfully, but the expectation is that the limiting factors will be successfully overcome in the not too distant future.

The distinguishing characteristic of continuous casting for the purposes of this study is that this method eliminates the need to cast steel into ingots, and then soak and reheat them for rolling into semifinished forms, such as slabs and blooms. This process eliminates nearly 50 percent of the home scrap originated under the conventional method, the principal reduction arising from eliminating crops (cutoff pieces) conventionally originated in blooming and slabbing mills. In addition, the continuous casting process results in a

To the extent that scrap is used in the blast furnace, it tends to be low-cost types, such as borings and turnings, tin cans, and other light scrap from incinerators.

much lower level of nonrecoverable losses (about one-third lower); therefore, it is more economical in raw material consumption per ton of steel.

Table 2 summarizes the differences in raw material requirements between the conventional method of making steel and continuous casting, assuming the use of the current 45 percent overall proportion of scrap to total metallic input in steelmaking. It shows the materials required on both a gross and a net basis to make 100 tons of finished steel products. On a net basis, the continuous casting process requires 7 percent less of raw materials because of the lower volume of nonrecoverable losses. On a gross basis, however, the amount of raw materials needed with continuous casting is 16 percent less, reflecting additionally the fact that a much smaller amount of material (47 percent less) is diverted temporarily (via home scrap recoverable losses) from being transformed into finished steel under continuous casting as compared with the conventional method. As a result of these facts, particularly the expected sharp decline in home scrap produced, the demand for purchased scrap would rise 11 percent and for pig iron would decline about 14 percent, if the current 45 percent scrap proportion were to be maintained.

The assumed maintenance of the 45 percent domestic steelmaking scrap proportion in table 2 is convenient for studying the nature of the effects of continuous casting on an abstracted basis. However, if continuous casting were substituted

1 Does not include the small additional amount of other ferrous raw materials-iron ore and ferroalloys-also used in the making of steel. This has recently averaged out to the equivalent of about 5 percent of the scrap and pig iron charge.

Includes ingot molds and stools, required under the conventional method. These are, of course, blast furnace or cupola products. Their inclusion raises the overall scrap proportion under the conventional method somewhat above the 45 percent used for steelmaking per se.

Source: U.S. Department of Commerce, BDSA, Office of Metals and Minerals.

for the conventional method throughout the steel industry, the decline in home scrap would make it impossible to maintain the current domestic steelmaking scrap proportion, because not enough scrap would be available, even if all originated scrap were to be processed and used, and all scrap exports diverted to domestic use. The likely effects of continuous casting on steelmaking under these cir cumstances would be to decrease home scrap origination rates and usage by over 50 percent, to keep purchased scrap at the same relative level, to reduce the relative use of pig iron by about 8 percent, and to decrease the average scrap proportion in steelmaking from the current 45 percent to about 41 or 42 percent. The reduced net demand for ferrous raw materials under continuous casting is the factor which will lower the relative use of pig iron. This factor also will tend to exert some downward pressure on scrap prices.

The expansion of continuous casting is likely to increase the demand for purchased scrap-including No. 2 bundles-for use in BOF's, even under present furnace technology. Under the conventional casting method, the BOF originates approx. imately the amount of scrap (for its 28 percent scrap proportion) which can be economically used. Under continuous casting, it will originate only half as much scrap, and will tend to use purchased scrap to make up the difference. The low scrap proportion used in BOF's would give these furnaces a relatively great tolerance for No. 2 bundles, as the contaminants in these bundles could be readily diluted with the relatively large amounts of hot metal used.

IRON ORE AND BLAST FURNACE
IMPROVEMENTS

Over the past decade there have been a number of technological developments in the beneficiation of iron ores and in the improvement of blast furnaces, which have increased competitive pressures

on scrap.

Better Beneficiation of Iron Ores

Low grade ores, such as taconite, which run around 20 to 25 percent iron content, have been increasingly beneficiated and pelletized, bringing the iron ore content to about 62 percent, about the

It has been shown elsewhere in this study that all "acceptable" scrap generally has tended to be consumed (cf., chapter 6).

same as occurs naturally in the best ores. Moreover, the characteristics of the pellets are such that their use reduces substantially the amount of time it takes to make a furnace load of hot metal. Other forms of concentrating the iron content also are used, such as sintering, with similar desirable effects. The cost advantage of using these concentrated forms to replace high grade iron ores stems principally from increasing blast furnace productivity.

Blast Furnace Improvements

At the same time that these improvements in beneficiation were taking place, the speed of blast furnace operation was being markedly improved by the use of oxygen and natural gas, the use of high top pressure (not yet widely applied commercially), and increases in the temperatures of the hot blast injected into the furnaces. The combination of both the beneficiation and blast furnace improvements has roughly doubled the productive capacity of the many blast furnaces in which they have been used.

Thus, the cost of hot metal, the principal competitor of scrap, was reduced and blast furnace capacity was markedly raised. Until this capacity increase, of which more is yet to come, is absorbed by the growth of the economy and of steel demand, the competition to scrap from hot metal will be particularly severe. Many steel producers will prefer to use their hot metal capacity so long as their variable costs are less than the

cost of scrap; and some will even push beyond this point.

Direct Iron Products

Considerable improvement has taken place over the past decade in the preparation of direct iron products, such as sponge iron, which can be used directly in steel furnaces to replace scrap or pig iron. These products are made by a number of processes and have many different names; they are often, but not necessarily, processed from relatively high grade ores (around 60 percent iron content), the iron content being raised in the course of processing to generally between 90 and 98 percent. However, the cost of making direct iron products is relatively high, rumored to be in the midthirties (dollars) per ton, and appears warranted in this country only when scrap prices become relatively high. A few experimental direct iron plants were operated in this country in the midfifties, when scrap prices were very high, but they are not being used currently.'

Thus the competition from direct iron products is not a scrap problem at the moment, but further technological improvements could change this. The existing unused capacity may be used again when and if scrap prices rise enough, and would tend to keep scrap prices from moving as high during cyclical peaks as they have sometimes done in the past.

The direct iron process is being currently used to a limited extent in several foreign countries in unusual supply situations.