NICKEL EXTRACTION BY THE MOND PROCESS1 By Sir William Chandler Roberts-Austen The rules of the Institution provide that an Associate shall submit a Paper within a year of his election. In complying with character of this direction, the Author was sat Original the Process. isfied that no better subject could be selected for consideration than the interesting process which marks an entirely new departure, in metallurgical practice, from the principles which have hitherto guided it. This process depends on the remarkable property possessed by nickel of forming a volatile compound with carbonic oxide, or, as it is called in modern chemical nomenclature, carbon-monoxide. When this gaseous compound is heated to 180° C. nickel is released in the metallic form. the Sudbury The Sudbury Ore. The Author was much impressed during a recent visit to Canada with the Imperial Points of importance of the great nickeliinterest of ferous district of Sudbury, Ontario. deposit. In view of the magnitude of this deposit, the annual production of metallic nickel in Canada seems inadequate, as it has hitherto not exceeded 2,750 tons netic pyrites) and copper pyrites. These sulphides form enormous masses near the margin of large areas of diorite, or weathered gabbro of Huronian age, the amount of nickel contained in the ore averaging between 23 per cent. and 10 per cent., the lower pro portion being the more common. It is worthy of note that pyrrhotine from other parts of the country, found in association with Laurentian rocks, is almost barren of nickel. The importance of the nickel deposits of Ontario may be judged from the fact that, until the mines in the Sudbury region were worked, the world's supply of the metal was drawn chiefly from the mines of New Caledonia, an island in the Southern Pacific, supplemented by the Gap mine in Pennsylvania, and a few isolated mines in Norway and Hungary. The extent of the Sudbury deposits is greater than any of these, and New Caledonia, which belongs to France, is virtually the only rival of Ontario in the production of nickel. The ore at Sudbury is smelted into a regulus, or mat'e, which contains between 12 Mattes of per cent. and 20 per cent. of the Ore. The nickel, and about the same amount of copper, although usually there is rather more copper than nickel. This matte may description therefore of any new process which affords a hope of hastening the development of this remarkable district should prove to be interesting. The deposit itself presents many points of interest. According to Professor Coleman of Toronto, the nickel ores of Ontario resemble the gold ores of Rossland in British Columbia, as they consist of a mixture of pyrrhotite (mag 1 This paper on the Mond Process by Sir. W.C. Roberts-Austen, D.C. L.. F. R.S., was read before the Institution of Civil Engineers, London, England, on 8th November, 1898. It is printed in this Report of the Bureau of Mines, with the permission of the Author, as a paper which describes from the scientific point of view a most interesting process, that it is hoped may ere long be utilized in the treatment of Ontario nickel ores. Former extracting It is unnecessary to give a history of the metallurgy of nickel, but it may be well to state that Chronstet isolated the metal in method of the year 1751, and that Bergman the Metal. confirmed his discovery in 1774. The methods hitherto employed for extracting the metal from its ores are very complicated; they have involved concentrating the nickel either as a sulphide (matte or regulus), or as arsenide (speise) followed by either "dry" or "wet treatment. In the case of certain ores, wet methods only have been employed. The metallic nickel has always to be subjected to a process of refining, mainly, as in the case of cast iron, with a view to separate it from associated carbon. History of the Mond Process. As regards the process which forms the subject of this Paper a few brief historical details may be offered. In 1889 Experiments with Carbon Dr. Ludwig Mond, F. R. S., in Monoxide. . C. Metallic spots were, moreover, deposited on a cold plate of porcelain held in this luminous flame, just as spots of arsenic are obtained in applying the Marsh test for that metal. It was also observed that on heating the tube through which the gas was escaping, a metallic mirror was obtained, while the luminosity of the flame disappeared. On examination these metallic deposits were found to be pure nickel. The next step was to endeavour to isolate this curious and interesting nickeliferous compound, by preparing nickel with great care at the lowest possible temperature, and treating it with carbon-monoxide at about 50° C. The amount of the volatile nickel compound in the gases passing through the apparatus was thus gradually increased. The gases issuing from the apparatus were treated with a solution of cuprous chloride to absorb the excess of carbon-monoxide, and in this way a residue of several cubic centimetres of a colourless gas was obtained, containing the volatile nickel compound. By passing this gas through a heated tube the nickel and carbonmonoxide were again sep rated, and the volume of the carbon-monoxide thus set free was found to correspond to about four equivalents of carbon-monoxide to one equivalent of nickel. By further improving the method of preparing the finely divided nickel, and by passing the resulting gases through a refrigerator cooled by snow and salt, the investigators at last succeeded in obtaining the new compound in a liqu d state, and were able to produce it with facility in any desire collaboration with Dr. Carl Langer, was engaged in working out a method for eliminating the carbon-monoxide from gases containing hydrogen 1 which they wanted for use in their gas battery.2 In attempting to effect this, they were guided by the observation they had previously made that finely divided nickel has the remarkable property of removing carbon from carbon-monoxide at a temperature of 350 C., converting it into carbon-dioxide, while the dissociation of carbon monoxide by heat alone, according to Victor Meyer and Carl Langer, remains incomplete at the high temperature of 1,690 quantity. C. In the course of these experiments, which they carried out in conjunction with Dr. Friedrich Quincke," finely divided nickel formed by reducing nickel oxide at 350 C., by hydrogen, was treated with pure carbonmonoxide in a glass tube at varying temperatures. In order to keep the poisonous carbon-monoxide out of the atmosphere of the laboratory the gas escaping from the apparatus was ignited. They found to their surprise that while the tube containing the nickel was cooling, the flame of the escaping gas became luminous and increased in luminosity as the temperature sank below 100° Metallic Carbonyls. Nickel carb nyl in its pure state is a colourless liquid boiling at 43 C.; it has a specific gravity of 1 3185 at 17° C., and Combining with Nickel solidifies at -25° C. into needleand Iron. shaped crystals. It is soluble in alcohol, petroleum and chloroform; and it 1 Ludwig Mond and C. Langer. "Improvements in obtaining Hydrogen," British Patent No. 12,608, 1888. 2 Ludwig Mond and C. Langer. "A new form of gas battery." Proceedings of the Royal Society, vol. xlvi. p. 296. 3 Ludwig Mond, C. Langer, and F. Quincke. Journal of the Chemical Society, vol, Ivii. p. 749. is not acted upon by dilute acids or alkalies. It can be readily distilled without decomposition, but on heating the vapour to 150 C., it is completely dissociated into its components, pure carbon-monoxide being obtained, while the nickel is deposited in a dense metallic film upon the sides of the vessel in which the compound is heated. After the production of nickel carbonyl had become easy, Drs. Mond, Langer, and Quincke directed their attention to the action of carbon- monoxide on other metals. A series of experiments was made with a view to obtain a similar compound with cobalt, which in its chemical and physical behaviour so much resembles nickel. The experiments gave, however, the unexpected result that, unlike nickel, cobalt will not combine with carbon-monoxide. Experiments were then made with iron, and indications were soon obtained of the existence of a volatile compound of iron aud carbon-monoxide; a long time elapsed before this new compound was obtained in a pure state. It was finally isolated in a way similar to that by which the nickel carbonyl had been prepared, and proved to be a somewhat viscous liquid of pale yellow colour. 4 Its specific gravity at 18° C. is 1 4664; and it distils completely without decomposition at 102-8° C. under a pressure of 749 millimetres of mercury. When cooled to -21° C. it solidifies into a mass of yellowish needle-shaped crystals. Its chemical composition is somewhat different from the nickel carbonyl, as it contains five equivalents of carbon-monoxide to one of iron. The liquid compound, to which the name of iron penta-carbonyl was given, undergoes no change when protected from the action of light, but exposure to daylight for several hours in a sealed tube is attended with the formation of gold-coloured, tabular crystals, and carbon-monoxide is evolved, so that the pressure in the tube rises considerably. The crystals have, when dried, a metallic lustre, and resemble flakes of gold; they contain two equivalents of iron to seven equivalents of carbon-monoxide. 4 Ludwig Mond and Carl Langer on "Iron Carbonyls." Journal of the Chemical Society, vol. lix. p. 1090. None of the other metals which were submitted to investigation showed indications of combining directly with carbon-monoxide. The discovery that in a mixture of metals only nickel and iron would form volatile comLaboratory pounds with carbon-monoxide, and experiments with Nickel that they could, therefore, be sepOxide. arated from the other metals, was sufficiently important to induce Dr. Mond to arrange laboratory experiments with ores containing nickel, cobalt, iron, copper, etc., such as "kupfer-nickel" and "pyrrhotite." The experiments afforded such promising results that apparatus of considerable size, though still well within the limits of the resources of a laboratory, was set up, and in it several pounds of ore could be treated with carbon-monoxide. 5 A patent was also applied for on the 12th August, 1890, which describes the way in which such ores may be treated. It is pointed out that the principal nickel ores which are metallurgically treated contain the nickel in combination with arsenic and sulphur besides other metals and gangue. These ores have first to be submitted to the process of calcination, in order that the nickel may be present in the form of oxide, and to drive off, as far as is practicable, the arsenic, sulphur. and other volatile bodies. The resulting oxide of nickel is treated with reducing gases, such as water-gas or producergas, in order to convert the oxide of nickel into finely divided metallic nickel; the material containing it then is cooled to about 50° C., and is treated with carbon-monoxide. In dealing with nickel ores which contain nickel oxide in chemical combination with silicic acid, arsenic acid, or other substances which cannot be removed by calcination, the ores are so treated as to convert the nickel into nickel speise or nickel matte, which is then subjected to calcination. The Smethwick Plant. In 1892 an experimental plant on a large scale was erected at Smethwick, near Birmingham. After some years of patient work, during which the plant had several times to 5 Ludwig Mond on "Metallic Carbonyls." Proceedings of the Royal Institution, vol. xiii. p. 668. |