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and carbon, 49.90. This bed presents also the great disadvantage in mining it that innumerable joints run through it at right angles to the strike and dip, undoubtedly resulting from great pressure, and that the coal is very hard and brittle, so that in undermining only slow head way can be made, and a very large proportion of waste results.
In regard to the Colorado beds now opened I cannot give any details, as I was prevented from visiting the mines.
The coal mines along the Union Pacific Railroad have furnished a considerable product since they were first opened in 1868, viz: There were mined by the Wyoming Coal and Mining Company
Altogether by these two companies, up to the end of
The capacity of the mines of the Rocky Mountain Coal and Iron Company has been much increased lately, so that in the first three months of 1872 this company has been able to mine and ship 24,933 tons.
Almost all this coal has been used up by the two great railroad companies, the Union Pacific and the Central Pacific, the quantities shipped to San Francisco and other points being insignificant.
Here, then, is an almost inexhaustible source of supply for the pressing wants of the metallurgical works of the Great Basin and the Pacific States and Territories generally.
But if you suggest the use of these lignites for metallurgical purposes to the superintendents of works in those regions, you receive the unanimous answer that they are not fit to be employed for the production of high temperatures. You are told that the main difficulty in using this coal is the fact that it breaks into small pieces as soon as it is exposed to the heat; that in the fire-box of the reverberatory the draught cannot after that penetrate it, and that in the frequent stirrings which are necessary the small pieces fall through the grate half burned, while on account of the frequent opening of the fire-doors for the purpose of stirring the fire a great part of the heat produced is lost. In the blast-furnace, it is claimed, the blast cannot penetrate the fine coal and ore, and thus the necessary temperature is unattainable.
Such and similar opinions in regard to this coal are held by almost every one connected with mining and reduction in the far West. It is considered a settled affair that this coal cannot be used to advantage in metallurgical operations.
Now let us see whether this is really the case; and to do this, we must
first examine the experiments by means of which people have arrived at such a conclusion.
As to the experiments for the use of this coal in reverberatories there are two unsuccessful ones on record, one in Colorado, the other in Utah. In both cases the grate used in the common fire-box was the horizontal grate, and the supply of air was provided by the draught of the chimneys only. In both cases the coal broke up into small pieces, and could not be burned rapidly enough to produce the required temperatures.
In blast-furnaces these lignites have been frequently tried in different localities in the West. But no smelting temperatures could be attained and the furnaces would come near chilling. This effect was also rightly attributed to the cracking and breaking up of the coal, and its use in blast-furnaces in the raw state is now virtually given up. I should mention here that the blowing-engines used in the West are ventilators, with which you can produce no pressure, and Root's blower, with which you can reach a very slight one. But then it was proposed to first coke the coal. To look at the analyses of these coals there appears to be no good reason why it should not be possible to make good coke of them. But it is the unanimous verdict of everybody, who has tried the experi ment, that no serviceable coke for smelting purposes can be produced from them. Specimens which I saw last summer at various places along the Union Pacific Railroad are certainly not calculated to encourage the idea that the existence of the lignites in this region is a guarantee for the perpetuity of the mining industry in that barren country. The coke is not at all coherent, in fact so soft that a slight pressure of the hand crumbles it into a thousand fragments. How could such material resist the pressure of the superincumbent mass in a blast-furnace? It is evident that it could not be used at all, for the powdered mass would give the blast less chance to penetrate than the raw coal. It would seem, then, at first sight, that the existence of these lignites brings no relief to a threatened industry. At least this appears to be the conviction of the majority out West, and we do not now hear of further experiments. Yet, what have those already made proved? They have proved that under the conditions given in the various trials the Rocky Mountain lignites cannot be used to advantage in metallurgy, and nothing more. But there are a great number of devices in modern metallurgy by which this fuel can be made to do effectual duty. I do not intend to discuss these at length, but I wish to point out a few ways in which, I am confident, the desired end may be easily reached. As to using this lignite in its raw state, in the common fire-box and on the common horizontal grate, with natural draught only, it might have been expected that a material containing 8 per cent. of hygroscopic, and certainly from 12 to 20 per cent. of chemically bound water, would fall to pieces and thus render the production of a high heat impossible; especially as so much heat is inevitably consumed in converting the water into steam. On the locomotives of the railroads, where no very high temperature is necessary, a sufficiently rapid combustion cannot be reached except through the increased draught by means of the exhaust; and even with this improvement the engineers on the Union and Central Pacific Railroads complain continually about the difficulty of keeping up steam.
But this whole difficulty can be overcome, as far as reverberatories are concerned, by using this coal in gas-generators, instead of in the common fire-place, and by doing the metallurgical work with gaseous fuel instead of the solid. I could adduce numerous examples, where lignites far inferior to those of the Rocky Mountains are used to great
advantage in this way, and some, where even the high temperature necessary in iron-works are thus produced. According to Tunner, gases from good lignites are capable of producing a temperature as high as 2,600 C.
The lignites of the West are eminently fitted for use in gas-generators; for the very fact that they break up into small pieces, when exposed to the heat, is an advantage, because it would be much the easiest, this way, to convert all the carbonic acid formed in the lower part of the generator into carbonic oxide, as a very large surface of glowing carbon is thus presented. They are not bituminous, and their contents in ash are so small that they will not interfere. It may be, indeed, necessary, and it is certainly highly advantageous, to use a blast under the grate in order to further a rapid development of the gases, but this has also the advantage that the danger of explosions will be lessened. It is my opinion that generators with stair-grates and under-blast will be found the most advantageous; and if still higher temperatures than can be produced by this means should be required, an increase can easily be obtained by using hot wind, both under the grate and for the combustion of the gases.
But the use of the lignites in blast-furnaces is of far higher importance to the western mining districts than that in reverberatories. Experiments so far have proved unsuccessful, principally, I am sure, because with the blowing-engines in use the required pressure could not be attained. To burn that material in the blast-furnace, cylinder-blasts are required, and perhaps it would also be necessary to close the tops of the furnaces in order to smelt under a high pressure, which may be regu lated by the damper in the flue. The extraordinary results thus attained in producing high temperatures by Bessemer are too new to require recalling. Nothing of this kind has, however, yet been tried in the West, but I hope that during the present year this subject will be thoroughly investigated.
The coke produced from the lignites by the simple method employed is, as I have said before, not fit for the blast-furnace. But the coal used was, as far as I am aware, of the inferior kind occurring in Colorado and in the Wasatch near Coalville. The Rock Springs coal, which is by far the best lignite, has not been tried. And if, instead of trying to coke this material in imperfectly constructed bee-hive ovens and in pits, more perfect apparatus, like the Belgian oven or Appolt's oven, had been used, I think the result, even with the poorer qualities of Rocky Mountain lignite, would have been more encouraging. The Rock Springs coal, I am confident, will make coke in good apparatus, and if it should not be quite as firm as required for the blast-furnace, its hardness might be increased according to experiments which I learn were made in the West several years ago, by coking it under pressure. To produce this pressure in the coking-ovens the escape of the gases need only be regulated; and the ovens themselves must be constructed with the special view of resisting a pressure from within. Success in this direction would of course be of the utmost moment; for even if we assume as a settled fact that the lignites can be used in the blast-furnace with the proper blowing-machinery, in a raw state, their high percentage in water will always be fatal to the production of very high temperatures and their maintenance. It is, besides, much more agreeable and economical to use coarse fuel than fine stuff, as every smelter well knows.
Finally, I wish to draw attention to the importance which these lignite-beds have in regard to the vast magnetic-iron-ore deposits near Laramie, and the hematites of Rawlins. The latter are very pure, and
rich in iron, and the former also contain nothing deleterious except a little sulphur, the precise amount of which I have forgotten. If a method is found in which good coke can be made from the coal, there is of course nothing in the way of the railroad companies making their own rails, but if this should not be the case, it seems to me highly desirable that the late experiments of Siemens and Pousard, for the purpose of making wrought iron and steel directly from the ore; and so avoiding the blast-furnace, should be continued with a special view to the utilization of the iron-ores and lignites of the far West. It is true that the respective means employed by these two gentlemen, though technically successful, have not been so economically. There are, indeed, at the present time experiments going on in this country with apparatus different from those used by the English and French engineers, which are very likely to solve this problem favorably, it being the special object of these experiments to produce large quantities of iron in a given time, and with the greatest possible economy in fuel.
THE METALLURGY OF NATIVE SULPHUR.
The discovery of large quantities of native sulphur, mixed more or less with earthy matter, in Nevada and Utah, and quite recently in the so-called Yellowstone region in Wyoming and Montana, induces me to say a few words in regard to the above subject.
All those of the above sulphur-deposits, which I have examined personally, owe their origin undoubtedly to the condensation of sulphurous vapors in the overlying colder layers. They are situated in volcanic regions, in some of which the subterranean forces are still active, the deposition of sulphur going on continually at the present time.
To determine the amount of sulphur which can be extracted profitably by the methods of beneficiation now in use, on a large scale, several simple tests are employed, one or two of which will be briefly mentioned. According to Anthon,* two grams of coarsely pulverized ore are heated in a glass tube of 10 to 16 inches in length and four lines in width, which is closed on one side, and into the open end of which another tube, also closed on one side, is introduced up to within 3 inches of the ore. When no more sulphur issues from the ore, that piece of the latter tube in which the sulphur has been condensed, is cut off and weighed. The sulphur is then removed, and the empty tube weighed again, the difference of the two weights giving the available amount of sulphur in the ore. To make the test on a larger scale, one or two pounds of the crushed ore are introduced into a good clay retort, which is put into a wind-furnace, so that its neck protrudes about 15 centimeters. To this a porcelain tube is luted, one end of, which just dips into water. The retort is now heated to a strong red heat; the sulphur-vapors are condensed in the porcelain tube and the liquid sulphur drops into the water. When there is no more sulphur in the ore, the tube is taken from the retort, heated strongly over the water, and the sulphur, which has remained in it in solid form, will also be collected in the water. The whole product is then taken out, dried carefully, and weighed.
For the utilization of the sulphur from the class of ores here under consideration various methods are in use, which can be classed under two main heads:
1. Eliquation of the sulphur in entirely open or partly closed apparatus. 2. Eliquation, sublimation or distillation of the sulphur in closed fur
The methods coming under the second head require considerable. ontlay of capital for apparatus, and greater expense for labor. They also require fuel. In their favor, however, is the more perfect extraction and utilization of sulphur which they effect; but the gain by these methods is not great enough to overbalance in our western Territories the increased expense of securing the product. In some regions the absolute want of a cheap fuel precludes their employment altogether. For these reasons I shall not dwell on them here, but rather present a description of a few of the methods belonging under the first head.
a. Melting of the sulphur in cast-iron kettles.--This method can only be employed with profit in working the richest ores, containing over 70 per