1845.1 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



153 



necessity of Laving the silex separated. Some contending, that when vitri- 

 fied by a due proiiortion of lime, llie resulting glass was rather advantageous ; 

 while others maintained, that such a glass was not obtainable from silcx and 

 lime alone, and that the presence of the former, unaccompanied by clay, rc»- 

 dered many ores of iron comparatively valueless, there being much ditficulty 

 in reducing the silicatcd oxides of iron, which such ores would form when 

 exposed, per se, to a high temperature. 



It appeared to the author, that the investigation of the phenomena, at- 

 tendant on the fusion of the earths generally found commingled with iron 

 ores, was of the greatest importance, and that much of the successful prac- 

 tice of iron smelting depend on the proper vitrification of these earths ; that 

 an important analogy existed between the manufactures of glass and pig iron, 

 and that in order to accomplish successfully the production of the latter, it 

 would he necessary to study the theory of the former. When this was done, 

 he conceived that,' more particularly with reference to the richer descriptions 

 of ores, the mists which were generally supposed to envelope the manufac- 

 ture of pig iron, must be rapidly dispelled before the advancing light of 

 science, and that many results, now looked upon as unaccountable pheno- 

 mena, would be reduced to their more rational position, as calculable effects 

 from appreciable causes. 



[The author, after explaining the vitrification of silcx, then proceeds to the 

 more immediate details, and observes — ] 



On Rkuuction ok tuu Ore. — Still looking at it in its scientific bearings, 

 he cannot but think, that a magnetic iron ore is, as it ought to be, the most 

 easy of reduction, if that reduction be prosecuted on sound chemical princi- 

 ples, lie presumes that he may designate those as magnetic ores, which, 

 like the Turkish, contain a proportion of protoxide of iron; but at present 

 he would confine himself to the richer classes only. It seems singular, that 

 this description should be the one universally used (as far as he can learn) in 

 the old bloomeries, or in the improved form of that furnace, — the Catalan 

 Forge. In America — in India — in Prussia, and in Spain, these ores alone 

 seem to be used. Is it not probable, because their state of diminished oxi- 

 dation renders their reduction more facile, and if readily brought into the 

 metallic state by the crude action of the blast in the bloomery — a priori, 

 why should not they, when once in that state in the high blast furnace, be 

 as readily impregnated with carbon to make cast iron ? 



Rich Iron Orfs. — He looks upon it, that the reason why the English 

 iron-masters of the present day, consider the reduction of the rich ores a 

 matter of such doubt and difficulty, is, because they have only tried them, 

 and always treated them as of the same family as the leaner iron stones ; and 

 thus they practically find that they can use them hut in small proportions. 

 An extensive iron-master of Staflordshire told the author, that when be added 

 more than one-foniteenth part of the rich Ulvcrstone ore, he always endan- 

 gered the " gobbing up" of his furnaces. Now this was to be expected ; — • 

 with the red ore he was using oidy the same quantity of carbon as if that 

 much of some calcined " lean mine" had been used. When told that he 

 must use more coke, he declined, on account of the extra expenditure of fuel, 

 forgetting that the larger proportion of oxygen in the ore would require 

 larger dose of carbon, both for its decomposition and the impregnation and 

 smelting of the greater quantity of iron produced. 



Smelting. — From all he can gather, the writer thinks that the only diffi- 

 ties about the smelting of the Samakoft" ore, are its specific gravity, and the 

 fineness of its particles ; it would thus be carried down too rapidly through 

 the decomposing region, into the heartli of the furnace, and thus the carbon 

 in the upper parts would be rendered inoperative. With furnaces of a more 

 cylindrical form, he considers that this evil might he, in a great measure, 

 avoided ; there would not be that tendency to rapid descent of the portion 

 of the " burden" in the centre, which the egg-shaped sides of the present 

 charcoal furnaces seem necessarily to cause, hut the whole charge would 

 settle equally and regularly, as the portion below was reduced and consumed. 

 Such shaped furnaces may suit ores, even as fine as those from Samakoft', but 

 until they are fairly tried, there may be great doubt of the result, and it was 

 to the alternative of the two evils, — a strong blast, which blew the ore out 

 of the top of the furnace, or a weak one, which let it fall too rapidly to the 

 bottom, that the defective quality of the iron previously made, was ascribed. 

 To avoid all risk of suffering from either of these evils, the writer recom- 

 mended a modification of the process, which he had invented for the produc- 

 tion of wrought iron direct from the ore, {See Journal, Vol. VI., 1843, page 

 207,) and after trying it in a small way in a common foundry cupola furnace 

 at Mr. W. Fairbairn's works, at Manchester, with encouraging success, a 

 larger quantity of the ore was proenred from Turkey, and the process was 

 tried on a more practical scale at the Uackharrow charcoal furnaces, which 

 the liberaUty of Messrs. Harrison, Aiuslie, and Uoper, had permitted him to 

 use. 



The writer now proceeds to detail the results of this trial, apologizing for 

 the apparent prolixity of the preceding matter, trusting that the results 

 of the experiments may be deemed more professionally interesting, particu- 

 larly as bearing upon what must be an object of such vital importance in 

 every branch of engineering, — the quality of cast iron. 



Cast Iron. — 1120 lbs. of the Samakoff ore, imperfectly freed from the 

 silex by washing, were mixed up with half that weight of the riddlings of 

 charcoal (a comparatively valueless residuum from the blast furnaces) ; this 

 charcoal " breeze" being fresh washed, to free it from dirt, must have con- 

 tained, at least, one-third of its weight of water. The mixture was thrown 

 into a common puddling furnace, and lightly stirred about, every 5 minutes ; 



at the end of 35 minutes, the mass liaving become pasty, and palpably 

 " coming to nature," was withdrawn ; on being cooled, it was found to 

 weigh 8G7 lb., the loss of weight showing that the deoxidation had been 

 pretty far advanced. The quantity was so small, that it was difficult to fix 

 on any mode by which the i)roduct of the Turkish ore could be satisfactorily 

 separated from the current burden of the furnace; after some consideration, 

 Mr. Roper, junior, the manager of the works, decided on proceeding as fol- 

 lows : — 



At six o'clock on the evening of the 8th December, 1843, the customary 

 charges of ha:matite ore, in the Backbarrow furnace, were stopped, and 

 " false charges," that is, charcoal, lime, and other flux, without ore, were 

 continued to be used, till 10 o'clock ; it was then considered, that a com- 

 plete separation would be made by this great quantity of cliarcoal, &c., be- 

 tween the last ore charged and what was now to he used. The Turkish ore 

 was then used, in like weights, with their customary charge, and the last 

 charge was put in at midnight. About this time the furnace was tapped, and 

 a charge of white iron run out. 



No variation in the working of the furnace took place, until 10 o'clock a.m. 

 of the 9th, when it was clear to the workmen, and was soon ascertained by 

 Mr. Roper, that the furnace was working " light," i. e., making little or no 

 iron ; in other words, that all the ore charged previous to G i'.m. of the pre- 

 vious evening, or very nearly all, was then in a state of fusion, in the hearth 

 of the furnace, as pig iron ; it was consequently tapped, — less than the ave- 

 rage quantity of iron fas was to be expected), but of grey quality was pro- 

 duced. The furnace still worked "light" for two hours more, say to half- 

 past 12, when it began again to " make iron." No great change took place 

 till half-past 3, when a cinder, quite novel in appearance, but by no means 

 of bad quality, was tapped ; it was also accompanied with the dust of the ore 

 which had not (as usual) been separated by riddling ; at four o'clock the 

 hearth was tapped, and an excellent lot of very fluid pig iron was obtained. 

 This had also some marked characteristics : after becoming comparatively 

 cool, it was still fluid, and the workmen universally acknowledged appear- 

 ances which they had never seen when false charges (as is frequently the 

 case) had been used with the usual materials. The quantity rather exceeded 

 in weight the deoxidized ore introduced ; but this could scarcely be avoided, 

 as furnace must have been making some iron from its old stock, between 

 half-past 10 and half-past 12 o'clock. The opinions, both of Mr. Roper and 

 his men, were unanimous, that both from the means used, and the pheno- 

 mena exhibited, at least four-fifths of the iron made was from the Samakoff 

 ore. 



Bar Iron. — In the customary mode of making best charcoal bar iron, 

 from charcoal pig, it takes very nearly 30 cwt. of such pigs to produce 20 cwt. 

 of best hammered bar. Of this Turkish pig iron, it only took 26J cwt. to 

 produce a like quantity. That this remarkable difference is an effect of the 

 preparation or deoxidizement of the ore is proved by the same results fol- 

 lowing a trial with the Ulvcrstone ore deoxidized ; for 20 cwt. of pig, made 

 in a previous trial from such prepared ore, in like manner produced 20 cwt. 

 of bar. Time and opportunity have not yet been given to investigate the 

 cause of this striking and important phenomenon ; but the author thinks it 

 will he found, that pig iron so made from deoxidized ore will contain no foreign 

 matter but carbon, and all the silicon and other adulterative matter present 

 in cist iron, as customarily made, will no longer exercise their prejudicial 

 effects on the quahty. He does not mean to propose, that all cast iron 

 should be made from ore deoxidized in a previous operation, for the expense 

 would be palpably too great, but as respects charcoal iron, there is rather an 

 economy than otherwise, in so preparing the ore ; for the deoxidation by 

 means of the hitherto waste " breeze," and the coal for fuel in the puddling 

 furnace will, in his opinion, save the consumption of one-half of the charcoal 

 that would otherwise be used in the blast furnace. This is his conviction, 

 and upon this he intends to act, when he undertakes the dhection of the 

 Sultan's Iron Works ; but as he has not yet facts to refer to, he leaves for 

 the present the further description of the subject. 



Wrought Iron. — He then gives the result of the experiment for produc- 

 ing wrought iron direct from the Samakoft" ore, ( t'iile Journal, Vol. VI., 1843, 

 p. 82,) by the method invented by the author : — 222 lb. of this ore and 77 lb. 

 of coke dust, ground fine, were thrown into a furnace of Messrs. Rushton 

 and Kersley, at Bolton ; the mass was stirred about for 25 minutes, and then 

 222 lb. of BowUng pig iron were added : in an hour and a half from first 

 charging, 317 lb. of excellent puddled bars were obtained. If the weight of 

 the Bowling pigs be deducted, it will give 95 lb. of iron as the produce of 

 the 222 1b. of ore, or 44^ percent.; but if one-ninth he taken from the 

 Bowling pig (a very moderate computation) for " yield," there remains 120 lb. 

 as the produce of the Turkish ore — above 54 per cent. 



Mr. Fatrbairn having given a full account of Mr. Clay's treatment of the 

 finer pulverized ores of Samakoft", and of those of Ulvcrstone, by his process 

 of cementation in the reverberatory furnace, does not consider it neces- 

 sary to recapitulate the observations as to Mr. Clay's success, in producing a 

 perfectly crystallized grey pig iron ; the facts adduced are proofs of the 

 soundness of his views, and of the eflicicncy of the measures adopted for that 

 purpose. It may, however, become a subject for consideration and experi- 

 ment to ascertain, whether or not a cheaper and more direct process of de- 

 oxidation could be adopted; and as new discoveries, as well as new methods 

 of application, are of vast importance in the conversion of the mineral pro- 

 ducts, it may not be improper briefly to consider the proposed method of 

 smelting the fine ores, and further, to inquire into the nature of Mr. Clay's 



