THE EMERGENCE OF NICKEL Metallic zinc was used to produce golden brasses containing less zinc than those obtained by the calamine process.. By 1824 a Dr Geitner had devised a method of e
Trang 1assumed at this time most of the other responsibilities of the Cornish Metal Company including the purchase of ore from the Cornish mines Arrangements for smelting this ore were made with various companies which included the Harfords and Bristol Brass and Copper Company, and also the Freeman Copper Company To take advantage of the low price of coal and improved port facilities in South Wales, Harfords at that time moved their smelting facilities to Swansea and discontinued smelting in Bristol
Although the Birmingham industry flourished the Bristol company continued to decline By 1820 smelting at the Swansea site had ceased and by
1836, when the Baptist Mills site was sold, the company was no longer a manufacturing concern Its remaining properties had been leased in 1833 to a company partner Charles Ludlow Walker In these premises, brass continued
to be made and fabricated by traditional methods until the Saltford rolling mill stopped work in 1925 and brass making at the Avon Mill premises ceased entirely in 1927
Zinc in Belgium Attempts to obtain zinc directly from calamine were being made in the Liège district at the same time as William Champion was experimenting at Bristol Margraff, a somewhat legendary figure who was experimenting in 1746, appears to have passed on his results to the Liège professor Villette He in turn confided the information to the Abbé Dony who introduced the first commercially successful zinc reduction process (see Figure 1.7(c) above) Jean Jaques Dony was born in 1759 and, having been brought up in a brassmaking locality, he was greatly interested in the metallurgy of zinc The origins of the extraction process he evolved, however, are still very obscure It
is recorded in the Biographie Liègeoise, 1836, that ‘before 21 March 1805, Dony
had succeeded in extracting metallic zinc from calamine and had managed to melt and cast it in quantity’ In March 1806 he obtained from Napoleon an Imperial concession to exploit a deposit of calamine at Moresnet, and in 1807
he constructed a small factory in Isle Here, it is said, zinc was first produced in quantity
The limited room temperature ductility of zinc improves markedly if the metal is warmed slightly and Sylvester and Hobson of Sheffield first demonstrated the feasibility of producing zinc sheet by rolling at moderately elevated temperatures in 1805 Dony produced his first sheet of zinc in January
1808 and offered it, in acknowledgement of the concession he had been granted, to the Minister of the Interior After 20 July 1809 high-quality zinc was being produced in abundance, and an Imperial decree of 19 January 1810 granted Dony a patent, giving him a monopoly for the manufacture of zinc for fifteen years
Trang 2Between 1810 and 1818 considerable technical advances were made in the factory he established in the Liège suburb of Saint Leonard Here a rolling mill was producing zinc sheets 1.5m long by 41cm wide (59in×16in) by 1811, and
by 1813 the roof of St Paul’s Cathedral at Liège had been sheathed in zinc In the same year, in recognition of his Imperial patent, Dony sent to Napoleon his bust in Zinc, a casting weighing 74kg (163lb) Between September 1809 and February 1810 Dony had reduced the price of zinc in Liège from F8.60 to F2.60 Like all industrial innovators, however, Dony soon begun to encounter financial difficulties, and after 1818 he was forced to surrender all his commercial interests to his business partner Dominique Mosselman who, in addition to the calamine workings of Vieille Montagne, took over the entire factory at Saint Leonard Dony died in Liège on 6 November 1819, Mosselman died in 1837 His heirs established the Vieille Montagne Company which dominated the Belgian zinc industry for many years
Champion’s vertical distillation process, which had never made zinc at a price low enough to ensure its commercial viability, was soon superseded by Dony’s system Its use of massed banks of horizontal retorts reduced considerably the quantity of fuel required Fuel efficiency was improved even further when double-faced furnaces were introduced The clay condensers emerged almost horizontally from the ends of the fireclay retorts and were cooled by air rather than water as in Champion’s approach Dony appears to have stumbled, probably inadvertently, on a simple and very effective geometry for his condenser It is now known that the zinc vapour entering such a condenser from the retort is subject to a great deal of convection, and assumes a rapid revolving spiral motion round the inside of the condenser wall before condensation to the liquid state occurs
Soon after the Belgian process emerged, Germany, which had large deposits
of zinc ore in Silesia, developed a zinc furnace system which used retorts much larger and stronger than those used in Belgium This approach, which improved both labour and fuel economy, was possible because the Silesian ore had a coarse, porous texture which facilitated the egress of gas and zinc vapour from deep beds of ore The Rhenish retort subsequently developed was rapidly adapted throughout Europe, Britain and the United States The retort dimensions, a compromise between those of the Belgian and Silesian systems, were the largest which could be used for treating fine high-grade ore In crosssection the Rhenish retorts resembled an oval chain link, being about 18cm wide and 3ocm high (7in×12in) inside Regenerative furnaces became almost universal after 1900 and by 1920 fuel consumption had been reduced
to one tonne of coal per tonne of zinc distilled Careful tests made in Swansea
in 1851 on one of the last remaining Champion vertical retort plants showed that it required about 24 tonnes of coal to produce a tonne of zinc
The bulk of the world’s supply of zinc was produced in horizontal retorts until 1950 However, the process, being discontinuous, was labour and fuel
Trang 3intensive The first practical continuous zinc reduction process, introduced in the 1930s by the Imperial Smelting Corporation at Bristol, utilized a large vertical retort built of carborundum bricks which was fed by briquettes of roasted ore mixed with bituminous coal The labour requirement of such retorts was well below that of any earlier process The output of such a unit, around 9 tons of zinc per day, should be compared with the 60lb (27kg) produced by the best horizontal retort of that period
During the nineteenth century the possibility of devising an effective zinc blast furnace attracted the attention of many ingenious metallurgists, although little progress was made Labour and fuel were at that time very cheap commodities, and the world as a whole seemed content with the horizontal retort process This situation began to change rapidly after the First World War By that time profitable metallurgical enterprise had returned to the Bristol area, and lead and zinc were being refined at Avonmouth on a large scale The continuous blast furnace process developed by the Imperial Smelting Corporation took, in all, about seventeen years to develop and was not put into production until 1957
Like all successful and profitable innovations, the Imperial Smelting Process depends on very simple principles Thus, at 1000°C, the vapour pressure of lead is negligible compared to that of zinc It is also well known that when a bath of molten lead saturated with zinc is cooled, the zinc thrown out of solution contains less than 1 per cent of 1mpurities, and can be skimmed from the surface of the melt as a virtually pure metal The zinc blast furnace is charged with a mixture of lead and zinc oxides which are reduced by hot coke as in a conventional iron blast furnace The lead and slag produced by this reaction sink to the hearth of the furnace, where they are tapped and separated The zinc leaves the reaction zone as
a vapour and, mixed with the carbon monoxide formed by the reduction process,
is carried into the condensing chamber where it is absorbed by streams of molten lead Dissolved in this way it can safely be exposed to the atmosphere without serious risk of oxidation The lead is then slowly cooled and the layer of pure solid zinc which separates out on its surface is skimmed off The remaining molten lead
is then pumped back to the condenser
Each of these zinc blast furnaces can produce 60,000 tonnes of zinc per year, and at least ten are in operation throughout the world
Early applications of zinc
As a new exotic metal which had only recently become an article of commerce, zinc was of great interest to the experimentalists of eighteenth-century Europe, and it began to play an increasingly important role in their physical and chemical investigations Alessandro Volta demonstrated that the muscular contractions observed by Galvani were caused by electrochemical potentials
Trang 4associated with the moist contact of dissimilar metals (see Chapter 6) In one form of his voltaic pile, silver and zinc plates were used A cheaper and more practical version, however, was his ‘couronne de tasses’, or crown of cups, which used zinc and copper electrodes
Well before this time, however, it had been noted that the behaviour of zinc when immersed in water or aqueous solutions was very different to that of copper, iron or lead As early as 1742, Dr P.J.Malouin of Rouen had shown that zinc could be substituted for tin as a corrosion-resistant coating for iron utensils As described by Richard Watson, Bishop of Llandaff, the coating was applied to the surface of hammered iron saucepans by immersing them in an iron pot filled with molten zinc, sal ammoniac being used as a flux For a variety of reasons galvanized iron never seriously challenged tin plate in the manufacture of cooking utensils, and little further progress occurred until the second decade of the nineteenth century
In 1819 the French chemist Thenard began to appreciate that metallic corrosion was caused by electrochemical effects His ideas were subsequently developed by de la Rive, who in 1830 interpreted the rapid corrosion of impure zinc in terms of the localized electrochemical cells established between the zinc matrix and segregated impurities This led to the idea that corrosion might be inhibited by coating the metallic article with a thin layer of metal which would preferentially corrode and thus protect the substrate Sorel attempted to apply zinc to the surface of rolled iron sheet, and in 1837 he and
an associate named Ledru obtained a French patent for iron protected against corrosion by a hot dipped coating of zinc Sorel christened his new process
‘galvanizing’, in acknowledgement of the electrochemical background from which his concept of sacrificial protection had emerged
The English patent for galvanizing was granted in 1837 to Commander H.V Craufurd RN on the basis of a communication from Sorel It was exploited by the establishment in London in 1838 of the English, Scotch and Irish galvanised Metal Company, which started in Southwark and shortly afterwards, as demand increased, moved to Millwall Many components such as iron sheets, chains, nails and wire were treated In 1839 a very much larger organization, the British Galvanisation of Metals Coy, began to operate the process in Birmingham, paying royalties to Craufurd at a rate of £3 per ton of components treated Flat sheets of galvanized iron 1cm thick were supplied by this company on a considerable scale as roofing material for the new Houses of Parliament
Galvanized corrugated iron is first mentioned in 1845 in a patent taken out
by Edmund Morewood and George Rogers Morewood soon established works in the Black Country, where he galvanized black corrugated iron sheet obtained from J and E.Walker of Gospel Oak, London When Morewood ran into financial difficulties in 1847, J and E.Walker took over his plant and equipment in part payment of debts and transferred them to Gospel Oak The
‘G anchor O’brand of galvanized corrugated iron made at the Gospel Oak
Trang 5plant soon gained a world-wide reputation for its quality and reliability Vast quantities of galvanized iron sheet and utensils were exported to the expanding colonies and the profits made from bursts of trade stimulated by the gold rushes in California and Australia were very considerable Around 1850 the company designed and constructed a ‘beautiful Gothic villa’ constructed completely with galvanized corrugated iron which gained much attention During the nineteenth century zinc sheet became a popular roofing material
in its own right, being lighter and very much cheaper than lead Unlike corrugated iron, zinc sheet had no structural stiffness, although when properly applied to a suitably supporting surface it provided excellent protection After about 1850 zinc sheet was extensively employed for cladding the roofs of railway stations and other buildings
Although the hot dip galvanizing process afforded excellent protection against corrosion, it had the disadvantage of increasing significantly the dimensions of the articles being treated and could not, therefore, be easily applied to the routine coating of small components such as nuts and bolts where close dimensional control was required Galvanizing, normally carried out between 430° and 540°C also had a tendency to soften cold-rolled and heat-treated components Sherardizing, a process introduced by Sherard Cowper-Coles between 1900 and 1904, avoided many of the disadvantages
of galvanizing It was a cementation process, made possible by the high vapour pressure of zinc The steel or iron components to be treated were packed in sealed retorts in contact with zinc dust, and heated for 4–5 hours
at about 375°C, which is well below the melting point of zinc At this temperature, zinc vapour soon saturated the interior surface of the retort and diffused well below the surface of the ferrous components being treated, providing a corrosion-resistant surface without serious change in external dimensions This process, which after 1904 gained rapid commercial success
on both sides of the Atlantic, is still widely employed for the treatment of small, precise components It has the incidental advantage of producing a matte surface on the component which assists considerably the subsequent adherence of paint
THE EMERGENCE OF NICKEL Metallic zinc was used to produce golden brasses containing less zinc than those obtained by the calamine process It was noted in the eighteenth century that when zinc was added to copper in higher concentrations than those obtainable by cementation, the alloys obtained, which were usually used for brazing, were very much paler in colour Some of these were confused with another whitish alloy, paktong, which, in smaller quantities, had found its way
to Europe and Britain from the Far East since the sixteenth century It was
Trang 6hard, whitish in colour and, unlike the high zinc brasses, relatively ductile in the cold condition Being resistant to corrosion and free from the unpleasant taste of brass it was much favoured for the manufacture of musical instruments Although the metal nickel had been identified by Axel Cronstedt
in 1751, the composition of paktong was unknown until 1822, when analysis
by Fyffe of Edinburgh showed that it was, in essence, an alloy based on copper, nickel and zinc It was then being sold in the British Isles for about 12 shillings per lb, and was beginning to find fairly wide application as a cutlery alloy, largely because of its white colour and resistance to corrosion
It is uncertain when the Chinese first made paktong, although they made extensive use of a cupro-nickel coinage as early as the first century AD Paktong was first mentioned specifically in the Chinese literature by Kung Ya in the third century and a century later it was also being used for coins Some details of the method by which the alloy was manufactured were provided by Ho Wei in 1095 His description does not suggest that the Chinese were then aware of the existence of nickel as a metal in its own right, since the alloy was made by adding small pills prepared from the ore to a bath of molten copper held in a crucible When a layer of slag developed over the molten metal surface, saltpetre was added to the bath, the alloy was stirred, and the ingot was then cast It is not clear whether zinc was an ingredient of the pills prepared from the ore or whether the zinc was added at a later stage It is mentioned, however, that the ore came from Yunan, and it seems logical to assume that it would have contained arsenic and possibly iron in addition to the nickel During the eighteenth century cupro-nickel alloys in ingot form, which were sent from Yunan to Canton, contained approximately 30 per cent nickel and 20 per cent copper The ingots, in the form of triangular rings about 23cm in diameter and 4cm thick (9in×1.5in), were remelted in Canton, and zinc was added until the alloy was silvery white During the seventeenth and eighteenth centuries, paktong was shipped from Canton to England by the East India Company, both
in ingot form and also in the wrought condition
It was difficult to manufacture paktong from first principles in Europe since
a suitable source of nickel had not yet been identified Complex cobalt-nickeliron-arsenic ores were, however, available from the Schneeburg district of Germany, where they had been used for many years by the celebrated Blaufarbenwerke for the manufacture of cobalt blue and other pigments for the ceramic industry By 1824 a Dr Geitner had devised a method of extracting reasonably pure nickel from the waste products of the cobalt-blue process and set up a plant for the manufacture of nickel silver which he sold throughout Europe under the name Argentan at around three thalers a pound
In 1829, Percival Norton Johnson arranged with Geitner to operate the process in England A works for purifying the crude nickel speiss from Schneeburg was set up at Bow Common behind the Regents Park Canal in London, and from the nickel thus obtained ingots of nickel silver
Trang 7containing 18 per cent Ni, 55 per cent Cu and 27 per cent Zn were subsequently cast at Hatton Garden Between 1829 and 1832 Johnson, who was certainly the first man to refine nickel in the British Isles, produced, on average, about 16.5 tonnes of nickel silver a year Most of this was made into cutlery, and close plated by the Birmingham manufacturer William Hutton The cutlery was sold under the trade name Argentine After 1830 several other firms began to make nickel silver and the price of the alloy had fallen to four shillings a pound Johnson’s most serious competitor was the Birmingham firm of H & T.Merry, which was managed by Charles Askin and Brook Evans, the technical operations being in the hands of a very ingenious chemist, Dr E.W.Benson, who devised greatly improved methods of cobalt and nickel separation Around
1832, H & T.Merry changed its name to Evans & Askin and marketed a brand of nickel silver known as British Plate
Nickel silver made in Europe was generally known as Neusilber or Argentan The common designation in England was German Silver, although
it was also known as nickel silver, Argentine, Albati, and British Plate
The world’s consumption of nickel in 1850 was approximately 100 tonnes per annum, most of this being obtained from small arsenical nickel deposits such as those at Schneeburg and Dillenberg Usage of the metal increased slowly, until 1889 when the invention of nickel steels by James Riley of Glasgow created a demand which was difficult to satisfy The nickel pyrrhotite deposits of Norway produced about 4600 tonnes of nickel between 1848 and
1907 This output was small, compared to that of the garnierite deposits of New Caledonia, which were discovered in 1865 These deposits, which contained initially 10–12 per cent of nickel, produced ore and mattes equivalent in total to approximately 165,000 tonnes of metallic nickel between
1875 and 1915 By 1920 the nickel deposits of the island of New Caledonia were virtually exhausted
The famous nickel deposits of Sudbury, Ontario, are like those of Norway based on nickel pyrrhotite, although the ore is richer and more extensive They were discovered in 1883 when cuttings were being made for the Canadian Pacific Railway The next major nickel deposit to be uncovered was the Merensky Reef, near Rustenburg, in South Africa Since its discovery in 1924 this has become one
of the world’s major sources of nickel and some of the less common metals Very large cupro-nickel deposits in the north-western province of Gansu in China were discovered in 1958, and this area, where mining has developed rapidly since 1965, might well become a major source of nickel in future years
The world’s usage of nickel increased slowly in the second half of the nineteenth century Several European governments were attracted to the use of nickel silver as a coinage alloy, but were deterred initially by the difficulty of reconciling the nominal and actual values of the metals from which the coins were composed Switzerland, which introduced a nickel
Trang 8silver ‘billon’ coinage in 1850, solved this problem by including specified quantities of silver in the alloys used for the various denominations In
1879 the silver content was omitted and Switzerland adopted the 75:25 copper-nickel alloy which was already being used by Belgium, the United States and Germany
In the years which followed the introduction of pure unalloyed nickel as a marketable commodity, it came to be regarded as a metal which was difficult
to melt, cast and fabricate Although no serious problems were encountered in melting the metal in the coke-fired pot furnaces usually employed for melting carbon steel, the ingots obtained were often too brittle to be worked either hot
or cold Sometimes it was found that an ingot would crumble into fragments when hot working was attempted, whereas other ingots from the same batch could be cold rolled
This problem, which seemed to be analogous to the hot shortness of Bessemer steel (see p 167) was solved by adding spiegeleisen, an alloy of iron, manganese and carbon, to the melt, although this addition had a deleterious effect upon the corrosion resistance of the nickel sheet produced and it became necessary to use pure manganese In the Birmingham works of Henry Wiggin
& Co, nickel wire being produced in 1880 required between 1.5 and 3.0 per cent manganese to ensure ductility The standing melting procedure at that time was to reduce the carbon content of the melt to about 0.10 per cent by additions of nickel oxide, and then to complete the scavenging process by adding manganese in concentrations up to 3 per cent
By that time it had been found by Thomas Fleitman and other workers in the United States that magnesium was far more effective than manganese in improving the ductility of nickel and that lower concentrations were required The use of magnesium as a scavenger was confined initially to the United States until 1924 when the mechanism responsible for the variable ductility of nickel and its alloys was elucidated by Paul Merica and his co-workers at the National Bureau of Standards in Washington They were able to show that nickel was embrittled not by oxygen but by sulphur contamination of anything above 0.005 per cent The secret of success was to treat the molten nickel with
a metal such as magnesium which has a higher affinity than nickel for sulphur Any excess magnesium not required for desulphurization removed itself by evaporation from the melt
Claims to most of the significant ore bodies in the Sudbury district had been established by numerous prospectors, mining engineers and small companies soon after the initial discovery of ore in 1883 By 1886 most of the metallurgical assets had been acquired by the Canadian Copper Company under the leadership of S.J.Ritchie This company shipped most of its roasted ore to the Orford Copper Company of Bayonne, New Jersey, for refining Difficulties were encountered, however, in extracting the nickel since no satisfactory method existed at that time for separating the constituents of a copper iron nickel matte
Trang 9By 1891, however, John L.Thomson, the Superintendent of the Orford Copper Company, had devised an elegant method of extracting nickel from the Sudbury ore He utilized the ability of nitre cake, or acid sodium sulphate, to split up the molten copper nickel matte into two distinct layers The copper-sodium sulphide, being lightest, separated into the upper layer, while the bottom layer contained nearly all the nickel in the matte When the molten matte, thus treated, was allowed to cool very slowly in large pots, the two layers separated very sharply Thus was born the celebrated ‘tops and bottoms’ process The tops were transferred to convertors and blown to blister copper The bottoms were roasted
to remove all sulphur The black nickel oxide remaining was then reduced to metallic form in an open hearth furnace, from which ingots suitable for electrolytic refining were cast
The patent covering the Orford process was filed in May 1891, Thomson’s assistant C.C.Bartlett being named as the inventor Two years earlier, however,
a very much simpler method of extracting nickel from cupro-nickel ores had been discovered in London by Ludwig Mond After settling in London at the age of twenty-three, Mond had become deeply involved in the world of the chemical industry and in his forties had established the industrial empire of Brunner Mond & Co In the early 1880s he set up a private research laboratory at his London home, and here, in October 1889, his young Austrian research colleague Carl Langer, who had been heating finely divided nickel in a tube furnace under a current of carbon monoxide, became aware of
a remarkable effect The colour of the carbon monoxide flame, burned at a jet
as it left the furnace tube, changed from blue to a sickly green colour when the temperature of the nickel in the furnace fell somewhat below that of the boiling point of water
Mond was immediately called to see this strange effect, and found that a nickel mirror was deposited on the surface of a white porcelain tile thrust into the flame It was soon demonstrated that the gas leaving the furnace contained
a hitherto unknown volatile compound of nickel which was named nickel carbonyl It was found to form when carbon monoxide contacted pure nickel below about 110°C and to decompose above 180°C, when pure nickel, free from carbon was deposited, Mond appreciated very quickly that carbon monoxide gas could very well be the ideal leachant for selectively removing nickel from the Sudbury ores By 1892 he had demonstrated the effectiveness
of this approach in removing nickel from most types of ore in his London laboratory, and by the end of that year he had established a large-scale pilot plant at Smethwick, near Birmingham, on land belonging to Henry Wiggin This plant was soon extracting nickel from the Canadian ore at a rate of about 1400kg (3080lb) a week
By the end of the century the Mond Nickel Company had been established, and had acquired the Garson and Levack Mines in the Sudbury nickel complex By that time the Canadian Copper Company, united with its former
Trang 10allies and associates such as the Orford Copper Company, had transformed itself into the International Nickel Company and had transferred its refining operations from New Jersey to Port Colborne, Ontario, where nickel was extracted from the matte by the Orford process By 1921 the International Nickel and the Mond Nickel Companies were the only two organizations treating the Sudbury ores Mond Nickel had a smelter at Coniston from which the matte was shipped to Clydach in South Wales for refining by the carbonyl process Carbonyl nickel as originally produced at this plant contained less than 0.05 per cent metallic impurities, and since 1900 has been the purest grade of nickel commercially available
In 1905, fourteen years after the Orford process had been introduced, it was suggested by Robert Stanley of International Nickel that if the copper nickel iron converter matte then being received by the refinery was converted directly to metallic form instead of being laboriously separated into its constituents, it would yield a ductile, corrosion-resistant cupro-nickel alloy which could be of considerable value to the chemical industry Monel metal was named after Ambrose Monell, at that time president of the International Nickel Company It contained approximately 67 per cent nickel, 28 per cent copper and 5 per cent iron plus manganese In this natural alloy the copper and nickel retained the same relative proportions as in the converter matte The iron also came directly from the matte, the only intentional addition being the manganese which was incorporated to remove the last traces of sulphur from the alloy
Monel metal is still widely used where a ductile corrosion-resistant alloy is required In its colour, mechanical properties and ductility it resembles nickel, and it is resistant to anhydrous ammonia, sea water and a wide range of organic chemicals It is used for marine propellers and much marine hardware and at one time was used for roofing train sheds and railway stations in the United States Between the two world wars it was also used extensively for the manufacture of kitchen sinks and for the heads of golf clubs From such applications it has been largely displaced by austenitic stainless steels which are significantly cheaper
The Orford process was not superseded until 1950 when it was found that the converter matte, when allowed to solidify in its equilibrium condition, crystallized as a mechanical mixture of the copper and nickel phases These were separated by crushing the matte to a fine powder from which the nickel-rich phase was removed by magnetic and flotation processes
The International and Mond Nickel Companies have now combined their resources, and the nickel oxide produced by the new Inco refining process is turned into metallic form either by electrolytic refining or by the carbonyl process Monel metal, for reasons of control and economy, is no longer a natural alloy, but is produced by alloying copper, nickel and iron together in the desired proportions