March 6, 1879] 



NATURE 



4I1 



of the operation (excepting the small quantities of 

 hydrogen from the aqueous vapour of the air), these may 

 be caused to act upon iron pyrites and other mineral 

 matter. When pyrites is thus heated, an atom of sulphur 

 held in feeble combination is in great part expelled, and 

 thus is obtained protosulphide of iron, with which the 

 operation commences, and which can exist in the molten 

 state. Sulphide of zinc thrown into this bath of molten 

 sulphide is converted into oxide : the sulphides of copper, 

 nickel, and silver do not bum at all so long as sulphide of 

 iron is present, and, accordingly, if oxides, silicates, or 

 carbonates of these latter met^s are introduced into the 

 molten sulphide of iron, the iron present will take away 

 the oxygen with which the metals are combined and con- 

 centrate them into a regulus of sulphides. But the 

 question then arises. How, after fractional decomposition 

 by oxidation, we can separate the sulphides from the 

 oxides ? This is accomplished by the addition of siliceous 

 matter introduced into the furnace with the charge of 

 sulphides, so that in the manner explained are obtained 

 from crude materials five principal classes of products, 

 viz.: — (i) sulphur; (2) sublimates of volatile sulphides 

 and oxides ; (3) a slag of sihcates of certain more oxidiz- 

 able metals, principally iron ; (4) regulus containing the 

 nickel, copper,and silver; (5) sulphurous acid and nitrogen. 

 Under certain circumstances a sixth class of products may 

 be obtained consisting of the metals copper and lead. 

 Thus, when the sulphides of iron and copper present in 

 the bath are treated continuously with the blast of air 

 without the addition of combustible sulphides, a point at 

 length arrives when the whole of the iron present is 

 oxidised, and the regulus in the bath consists of sub- 

 sulphide of copper. If now a limited supply of air is 

 introduced, the copper is reduced to the metallic state, 

 with the evolution of sulphurous acid. Further ex- 

 perience in the matter may lead to the adoption of this 

 continuation of the process. Again, sulphide of lead 

 present in the bath may be caused to yield metallic lead | 

 by partial oxidation. The sulphurous acid can be made | 

 into sulphuric acid in chambers or condensed to the liquid I 

 state. Thus we have in this new process a metallurgical j 

 operation, the necessary heat for the decomposition and \ 

 fusion being entirely obtained by the combustion of the '■ 

 iron and sulphur contained in the materials operated on. | 

 Some large experiments have been made in order to prove \ 

 the more important points here enunciated. They are all 

 to be found described in the paper upon the subject in | 

 the Journal of the Society of Arts, dated February 14 

 and 21, 1879. -A brief record of some of the phenomena 

 witnessed at the February experiments at Penistone may 

 not be uninteresting. At seven in the morning on ' 

 February 12 last a small party of gentlemen arrived at 

 Messrs. Cammell & Co.'s Penistone Steel Works, in order j 

 to see the operation from its very commencement. Two 

 Bessemer converters were ready for the experiments ; one ■ 

 of these was charged at 10 a.m. with some molten proto- ; 

 sulphide of iron (made by fusing some pyrites in a cupola), ' 

 and a blast of air was driven through the tuyeres. Lumps 

 of sandstone were continuously thrown in together with 

 cupreous pyrites. A flame of the burning vapour of ! 

 sulphur expelled from the pyrites passed from the con- 

 •verter mouth to the chimney shaft ; it was from 6 to 10 

 feet long, blue at the edges and greenish in the body of 

 the flame. About noon this experiment broke down 

 through an accident, after which the product was taken 

 out. An experiment was then commenced by setting fire 

 to some sulphide of iron by means of about 2 cwt. of coal 

 thrown into the vessel to start the combustion ; pyrites 

 and sandstone were then thrown in, in lumps, which rapidly 

 melted, this being continued until midnight (over eight 

 hours). The molten mass in the vessel remaining per- 

 fectly liquid, was from time to time partially poured out 

 to make room for the addition of further similar materials. 

 During the whole of the eight hours not an ounce of coal 



was used, the converter being " fed with stones," and 



"vomiting forth fire and brimstone," as a gentleman 



present graphically expressed it. In this latter experiment 



about eighteen tons of raw pyrites was thus treated, and 



over four tons of sulphur was distilled and afterwards 



burnt. More than half a million cubic feet of sulphurous 



acid and nitrogen left the mouth of the converter at a 



high temperatiu-e, taking away with them a [^considerable 



fraction of the heat produced by the oxidation. This was 



j very unfavourable to the success of the experiment, as 



will be readily understood when this great loss of heat is 



; taken into account. With a suitable plant the heated gases 



; would be utilized to drive off sulphur from pyrites, so as to 



; produce the molten protosulphide required to continue the 



\ operation. Heat is not only obtained by the oxidation 



; of the metallic sulphides, but also by the oxidation of iron 



' protoxide to peroxide when the contents of the vessel are 



I over-blown. In an experiment made in July last the 



oxidation was thus purposely continued. " As soon as 



the subsulphide of copper began to bum a splendid 



emerald green flame suddenly appeared, lasting about a 



minute, and all the lines except those of copper and 



sodium left the spectrum. During the last few minutes of 



the blow the mouth of the converter was duU and without 



flame." 



Some of the products of these experiments were 

 shown at the Society of Arts ; they consisted of crystal- 

 line masses of ferrous silicate and blocks of 50 per cent, 

 copper regulus. No sulphur was collected, it being im- 

 possible to do so with Bessemer plant, which, in acti;al 

 operations, will not be used for the process. These ex- 

 periments, however, enabled those present to witness, in 

 the course of a few hours, the principal effects produced. 

 "A remarkable spectrum was obtained from the burning 

 sulphur vapour; viewed through a small direct vision 

 spectroscope, many absorption bands were seen occurring 

 at apparently regular intervals from the red to the violet. 

 The lines of sodiiuu, lithium, and thallium were recog- 

 nizable, but the majority of the lines are of (as yet) 

 unknown origin, though they are the most important, 

 since the changes furnish indications of the progress of 

 the chemical changes taking place in the vessel. The 

 lithium was, probably, derived from the sand introduced 

 with the pyrites." 



The process is peculiarly suitable — (i) For the treat- 

 ment of metalliferous substances which cannot be advan- 

 tageously utilised by other processes. For the extraction 

 of sulphur by distillation, and simultaneously for the 

 concentration and separation of copper, silver, and nickel 

 from such materials in the form of a metallic regulus ; 

 while lead, zinc, arsenic, &c., accrue in the sublimates. 

 (2) [For the treatment of cupreous pyrites, large quantities 

 of which exist in many parts of the world where fuel is 

 scarce, and where the present mode of treatment by the 

 cementation (wet) process involves not only the loss of 

 vast quantities of sulphur, which is burnt to sulphurous 

 acid, but causes the destruction of all vegetation within 

 its influence. For example — About one million tons of 

 pyrites, too poor in copper to pay for shipment to the 

 United Kingdom, are annually treated in Spain by the 

 cementation process. Such ores thus treated, containing 

 i\ per cent, of copper, leave only a small profit, whereas 

 it is calculated that similar ores by this new process will 

 yield a profit more than five times as great. (3) For the 

 treatment of copper and nickel ores, so as to produce a 

 concentrated regulus without employing carbonaceous 

 fuel. 



It is therefore obvious that this process wiU effect a 

 great revolution in the treatment of metallic sulphides, 

 such as iron, cupreous and nickeliferous pyrites, also 

 copper and nickel ores and the refuse gangue of mining 

 operations, which can thus be smelted without the 

 employment of carbonaceous fuel, the necessary heat 

 being obtained by the oxidation of the metallic sulphides^ 



