Abbildungen der Seite
PDF
EPUB

lbs. of muck bar, made from the 6000 lbs. of cinder, originally contained.

By referring to my first paper, it will be observed that an analysis of a finished bar, made by this process from Republic ore, showed an elimination of į of the phosphorus, but the foregoing shows even a better result from the muek bar from puddle cinder carrying 1:10% per cent. of phosphorus, while Republic ore only contains 15 per cent. I deduce from this that the proportion of phosphorus eliminated, whether the quantity be large or small in the ore or cinder to be worked, will always be such as to give value to a highly phosphoritic metal mixture reduced to iron by this process.

This system is also applicable, not only for iron oxides, but for all other metallic oxides requiring reduction.

An examination of the entire seven analyses shows results substantially alike, and proves how thoroughly impurities are separated in a few hours by this method.

Here is another important deduction, proving that even low-grade ores may be profitably worked upon this system. The mixture No. 1 was composed of 1800 lbs. of puddle cinder and 1200 lbs. of “old bed” ore.

To this 6000 lbs. of metal mixture was added 12 per cent. of earthy matter, so that the entire quantity of earthy matter contained amounted to 1617 lbs., while the 1842 lbs, of muck bar produced from it contained only •55 per cent. or 10163 lbs. of earthy residuum. An elimination of 1607 lbs. out of 1617 lbs. originally contained in the metal mixture.

This would show that ore or puddle cinder, containing 30 per cent. of earthy matter in all, can still have it eliminated down to 10 of one per cent., and I believe by a slight increase of lime it may be entirely separated.

This fact is worthy of consideration in connection with the lowgrade ores which so generally abound. Throughout the coal measures this class of ores are found, closely interstratified with the fuel, and by reason of this proximity produce iron at low cost. Yet because of the preponderance of sulphur and phosphorus, they are not satisfactorily worked alone in the blast furnace.

Turning to the recent Geological Survey of Pennsylvania, vol. "MM," page 179, I find an analysis of Westmoreland county ore containing 41 per cent. metallic iron and 50 per cent, volatile impurities and less than 10 per cent. of insoluble residue. This is a type of a large

variety of ores in Cambria, Huntingdon and, in fact, throughout the entire bituminous coal fields. Many of these ores contain more than ten per cent. of earthy matter, but rarely exceed 30 per cent., which has been referred to as so satisfactorily worked in the mixture designated as No. 4, where the earthy residuum was reduced to 16 of one per cent.

The facility of eliminating phosphorus so largely from puddle cinder containing nearly 2 per cent., as has been proved by the foregoing analyses, should be quite conclusive that the phosphorus can be readily removed from these ores of the coal formation when muck bar would then be produced from them at one heat not only at the lowest possible cost but of a very superior quality.

I have dwelt upon this branch of the subject because of its economic importance. If the gaseous and earthy impurities can be so easily removed from low-grade ores, as the result of the analysis of the No. + mixture would seem to prove, then the field of usefulness of this system will be much enlarged.

Within the last two weeks, still more satisfactory results have been obtained from working the charcoal-forge cinders at the forge of the Washburn & Moen Manufacturing Company, at Quinsigamond, Massachusetts. From these cinders, 1794 lbs. of blooms were produced from a small sand bottom reverberatory furnace, there being none there with cinder bottom.

The average yield, from the entire quantity of cinder used, was 38 per cent. of its weight in forged blooms. It was not unusual to shingle blooms of 150 to 180 lbs. in one hour from the time the mixture was charged in the furnace, while the average length of the heats did not exceed 11 hours. Four heats were made between ten o'clock and five, being an average of 17 hours, including the usual delays in repairing a sand bottom. Deoxidation was accomplished by using the fine breeze or dust charcoal, which is now wasted at charcoal forges. In this instance the tubes were 15 in. high, 8 in. diameter and 23 in. thickness.

The blooms thus produced, while still hot, were for a few minutes reheated and then rolled to muck bars. These bars were cut up and, with an equal quantity of scrap, sunk in the charcoal-forge fire, then forged, reheated and rolled down to 1} inch wire rods, with no more than the usual waste in sinking iron in charcoal fires.

The rods so produced have all been rolled down to No. 6 wire, and part of it has been drawn to No. 12 size, with the intention to draw it

still finer if the stock will permit. Both the analyses, tensile strength and various further tests of this forge cinder iron is expected to be fully obtained within the next few weeks by this company.

The few experiments herein described have been the first attempt to make wire from cinders to my knowledge, and it is possible that the practical working of it may prove that the metal mixture was not sufficiently basic to eliminate enough silica and phosphorus to produce a very fine wire. Should such be the case, the difficulty can easily be removed in the future by slightly increasing the proportion of lime.

There are several elements of economy by this method that cannot be attained by producing pig iron from ore and then puddling it. To produce pig, it is essential to roast refractory and very impure ores and cinders before charging them in the blast furnace. This is required in order to expel volatile impurities as far as possible, as well as to render them more porous for the mingling of the gases.

Roasting is unnecessary for this direct method. By grinding the mixture together, properly proportioned, there is such close atomic contact created between the particles that reduction takes place rapidly without roasting. This is one element of economy.

Usually the mixture has been ground as fine as coarse Indian meal, but in the last experiment with forge cinder at Quinsigamond, just referred to, one of the mixtures was composed of one-half the cinder crushed to the size of small beans and the other half as fine as meal. The yield in metal and length of heat did not vary from that of the other forge cinder mixtures there, which were all ground fine, proving that very fine pulverization is unnecessary for forge cinders.

Another element of economy is in the item of fuel. Blast furnaces using bituminous coal require it to be coked, the better to carry the burden and secure greater purity of the gases from it. This operation of coking wastes a large portion of the combustible gases which should be used in reduction. Coking is unnecessary by this new system. Its cost and waste is saved. Bituminous coal, both for deoxidizing and fuel, is used without coking, and repeated analyses prove the iron is freed not only from its own impurities, but that it is uncontaminated by the impurities of the coal.

Still another economy may be counted upon. It is necessary to run the liquid pig iron from the blast furnace into moulds, which are freshly prepared, at considerable expense, for every cast. By this direct system, the metal mixture, automatically ground, mixed and

moulded, is charged at once into the reverberatory furnace as has been explained. The entire cost for labor up to this point is less than blast furnace labor.

Pig metal must be broken before charging. It comes to the puddling furnace cold, must be reheated and rabbled with exhausting physical labor, and at an intense heat, in order to separate the intimately combined carbon and silica, before it is changed to wrought iron ready for the squeezer and rolls.

By this system the metal mixture is reduced to a wrought or malleable condition at one operation from the ore. In 1} to 21 hours, according to the thickness of the moulded shapes, it is ready for the squeezer and rolls, and is brought to muck bar. It is then not only of superior quality to puddled iron, but is one step in advance of it in the process of manufacture; a step which requires from $12 to $15 per ton outlay on the pig iron to bring it to a malleable condition.

If the balled iron has been made from material nearly free from phosphorus, without squeezing, in its heated state, it may be transferred to and melted in the open hearth bath for steel, when it will separate from its earthy impurities by precipitation. If, on the contrary, the stock originally contained an objectionable percentage of phosphorus, the slag into which the phosphorus has been incorporated must first be squeezed out to guard against a second combination with the metal. Then the bloom, in its then highly heated state, may be at once melted in the bath, with the certainty of being freed from phosphorus. In either case a superior, cheap and uniform quality of metal is assured, adaptable, at pleasure, to any purpose required, from the best ingot iron, low in carbon, to the finest grades of high steel.

Practical tests, on a regular working scale, have thus far proved that the metal by this system will produce the finest grades of crucible, or open-hearth steel. Sunk in charcoal it makes fine grades of tough sheet iron, both of black and planished iron. Tests, not yet fully completed, are sufficiently advanced to prove that it will make a good quality of wire. In addition to this, as it can be proved that its cost is much below the cost of ordinary scrap or puddled iron--that its mode of working is simpler—that the cost for plant for a given quantity of iron or steel is very low--and that impure ores or cinders may be worked with safety, the process may reasonably commend itself to the close investigation of manufacturers. WHOLE No. Vol. CXII.—(THIRD SERIES, Vol. lxxxii.)

2

DISCUSSION Of the Papers of C. P. Sandberg on Roil Specifications and Rail

Inspection in Europe," of C. B. Dudley on the Wearing Capacity of Steel Ruils in Relation to their Chemical Composition and Physical Properties,and of A. L. Holley on Rail Patterns,at the

Philadelphia Meeting of the American Institute of Mining Engineers, held at the Franklin Institute, February 17th, 1881.*

ASHBEL WELCII, Lambertville, X. J.--Dr. Dudley has given the wear of steel rails under four different conditions. He arrives at the conclusion that the softer rails, or those that from their composition ought to be softer, wear better than the harder. But there is another condition which has an important bearing on the subject, and should not be overlooked--the weight on a wheel. With the lighter weights of the past, the softer rails may have worn best ; with the heavier weights of the future the harder may wear best. Weights will probably be increased up to the capacity of steel to bear; then, doubtless, the harder steel will wear best.

A leaden rail, with 10 pounds on a wheel, might carry millions of tons, but with 100 pounds on a wheel it would be destroyed by a few thousand tons. So in the days of iron rails, my experience was that the softer rails under light machinery stood better than some of the harder; but under heavy machinery the softer were much the most rapially destroyed. It is doubtless the same with steel.

The pounding motion of the wheels loosens or spreads the particles of a thin film of steel; the pull lengthwise on the rail detaches or scrapes them off. The softer the metal, the more liable the particles to spread or flow sideways; the more brittle, the more liable the particles to break loose. With light machinery, flowing may be practically nothing, with heavy machinery it may be enough to wear the rail out

The remarks as here given, as in the previous discussion of Dr. Dudley's papers, have all been written out or revised by the participants in the discussion, and represent, therefore, their mature views. It has been thought that this plan, when it can be carried out without doing any of the speakers injustice in debate, is much to be preferred to a strictly verbatim report. The remarks of Mr. Chanute were sent to the Secretary after the meeting, and although they did not form a part of the actual liscussion, there can be no doubt of the desirability of including them in this report.

! or Dr. Dudley's paper see JOURNAL for March and April, 1881.

« ZurückWeiter »