September_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | S E P T E M B E R 2 0 2 0 2 3 Geopolitics at the beginning of the 20thcentury causedanear 25-year unin- terrupted demand for nickel. Yet the af- termath of World War I pushed multiple concerns to the precipice of bankruptcy as easily accessible and cheaply mined surface ore was depleted. Disarmament treaties created a collapse in nickel de- mand (Sir Alfred Mond estimated 50% of nickel demand prior to the war went to armaments), while European stock- piles sent pricing into a deflationary spiral just as the British pound devalued 25%. Monel was on the chopping block. Yet Stanley, now first vice-president, took the unusual action of going all in at the height of the crisis. Seeing the need to diversify, he lobbied the board for $3million for a newMonel refining plant to bring mill production in-house. Stan- ley’s long-term bet paid off. As demand recovered in the mid-1920s, the Inter- national Nickel Company squeezed out the competition, leveraging their Sud- bury ore reserves and a new Hunting- ton, W. Va. plant to build the bottom line. Monel’s legacy continues in West Virginia to this day. MINING, SMELTING, AND REFINING From the very start of operations in Sudbury, ore was collected and separated into four grades: a mixed copper-nickel ore, copper pyrites, pyr- rhotite or nickel ore, and diorite rock. Composition varied widely in the early days, with nickel from 1.28-8.12% and copper 0.49%-15.71% between 1892-99 [2] . It was at the Sudbury Creigh- ton pit, mined from 1901, that veins of chalcopyrite and pentlandite were found in the pyrrhotite resulting in a 2.3:1 nickel copper ratio that became synonymous with Monel. Ore, hand sorted into three sizes, coarse, ragging, and fines, was syphoned off from waste rock and initially roasted in yards for up to nine months to lower sulfur content from 30% to around 7% [3] . Environmen- tal air pollution forced a permanent re- placement to roasting furnaces in 1929. Roasted material was smelted along- side “green ore” and “reverts” using a 3:1:1 ratio in blast furnaces. As top- grade surface ore was depleted during the war, sintering and reverberatory furnaces gradually gained in use from 1911. The product was finally Besse- merized in a converter to remove a 40% iron content through slag that was dumped as waste until collection began in the 1970s. Shipped to the United States, early refining took place in the original loca- tion of Orford’s works at Bayonne, New Jersey. While no evidence remains of the exact method, the original patent from Ambrose Monell describes the calcining of the Bessemerized matte to remove the sulfur, reduction of the oxides in a reverberatory furnace with carbon, and then copper or iron to al- ter the recipe appropriately. Later, pres- ident John F. Thompson confirmed this, noting Stanley added magnesium, likely for increased ductility [4] . In 1909, Browne filed a patent using lime in an electric arc furnace to separate off sul- phur through a calcium sulphide slag. At Huntington, the process was perfect- ed. The matte was ground into coarse sand by a jaw-crusher, cone crusher, and ball mill before entering a calcining furnace for four hours to remove the re- maining 20% sulfur. The resultant oxide Fig. 1 — The clear jump in nickel production into the outbreak of World War I. Fig. 2 — The huge swing in Canadian nickel production in the first quarter of the 20th century is shown in this chart.