Introduction
James Douglas came to mining by accident. He never intended to pursue a career in mining, but once it began, he pursued it with diligence and became highly successful. He rightly earned broad respect as a pioneer in metallurgy and as a business leader. The opinion of James Douglas on technology and metal markets mattered in a career spanning the formative years of North American industrialization. While the achievements he is most remembered for took place in Arizona and New York City, he remained forever proud of his Canadian identity and roots. Educated for a career as a Presbyterian minister, he lived a life characterized by honesty, generosity, and ethical business practices [5].
Today, I want to highlight his professional formation prior to 1880, prior to Arizona, prior to the Copper Queen Mine in Bisbee, and prior to the Phelps-Dodge Corporation (acquired by Freeport-McMoRan in 2007). His less well-known early career is best characterized by his experiments with “humid” processing of copper ore —experiments resulting in his 1869 patent with T. Sterry Hunt. This pioneering work with vat leaching is fundamental to his reputation in the mining world. In turn, it was this patented process that led to his all-important “graduate seminar” in mining—his overlooked 1871 copper consulting in Chile . His metallurgy and the lessons he learned in Chile , together put him on a path towards all that he achieved in his life. His pioneering work with hydrometallurgy , and his time among Chilean copper miners, confirmed for him the fact that hydroprocessing was the only option for making money from marginal sulphide ore . Moreover, he brought back from Chile the insight that the quality of copper ore matters less than the quantity. He observed in Chile that copper mining could be a business, and not just a speculation as he knew it in Canada [3, 7, 8].
Born in 1837, Douglas lived his early years in Quebec City. He died at age 81 in New York City. Following his 1918 death, lengthy obituaries reviewed his career. Eastern newspapers emphasized a rise to wealth that began at the “advanced age” of 40, while out west he was portrayed as the formal but always generous pioneer. Of course, the mining press paid their respects time and again. In addition to his work with copper , James Douglas was a prolific writer. Consequently, he was known not just for his efforts in Arizona, but also for his writing about the industry. He published upwards of 300 articles of various sorts and a handful of books. His writing offers challenging ideas. He wanted mines and metallurgical plants to be open so that ideas could be freely exchanged, as long as those ideas were patented and licensing fees paid [10]. He was a part of a generation that corresponded widely, and many of his business and personal letters have survived. Towards the end of his life in one letter he admonished his children, who were about to inherit a fortune in Phelps-Dodge and other shares, to never put share-holder value above worker well-bring [11].
An additional point I want to make concerns the importance of professional networking, with Douglas as a case in point. Scientific understanding moves ahead through information exchanges. Today, conferences and peer-reviewed publications are at the center of such exchanges, along with face-to-face conversations and correspondence. Over coffee or a drink, asides are made and heard. At social events, early just-formed ideas are shared and debated. Informal networking is the soil where new ideas first take root. Or at least, it was so in the nineteenth century. In the 1860 and 1870s, personal contacts were essential. This was an era when professional journals were just beginning and professional groups were still being organized. This was a time when university programs for industrial applications of science were only just starting to be considered. In Douglas’ day, it mattered a lot who you knew, and who you were.
It was networking that led Douglas to hydrometallurgy and Chile . His experience underlines the point about personal contacts. He came to the Hunt and Douglas Process as a result of conversations with the already renowned chemist, T. Sterry Hunt. Douglas related to Hunt the ore grade problems at the mine where his father was heavily invested. Douglas knew Hunt through Morrin College and the Literary and Historical Society of Quebec. Hunt, working for the Canadian Geological Survey at the time, in the winters of the mid-1860s taught chemistry at Morrin College. Hunt in turn had been a student of Benjamin Silliman, Jr., and a classmate of James Whelpley. Silliman, and his father Benjamin Silliman, Sr., were at the center of academic chemistry in North America; both worked at Yale University. Benjamin Silliman, Sr., was the founder and editor of the American Journal of Science, AKA, Silliman’s Journal. When Whelpley, with his partner Col. James Storer, accidently developed a humid process for extracting copper from its ore , they turned to Hunt to figure out the chemistry [4]. Knowing of Douglas’ financial trouble, right off Hunt related to Douglas the details of this “revolutionary” discovery. Douglas in turn brought the process to his father’s copper mine at Harvey Hill for field testing . While experimenting with the Whelpley and Storer Copper Process, Douglas tested alternative solvents. With one in particular, ferrous chloride , he liked the results. Again, Hunt worked out the chemistry. Joining forces, their new process was patented, and word spread to a copper broker in Liverpool, James Lewis. Lewis, after a visit to Quebec to see for himself, passed the news to a friend in Chile , Juan Stewart Jackson. Jackson, a banker and mine investor, was trying to help Henry Thorner (a Canadian dentist friend from Hamilton, Ontario), save his Chilean copper mine investments. At his mine, Thorner’s surface high-grade copper oxide outcroppings had given way to low-grade bornite. Jackson and Lewis arranged to bring Douglas to Chile as a consultant. All of this was carried out informally, people contacting people about problems and solutions. Networking shaped the James Douglas we know; by 1880 he was an expert metallurgist with a decade of experimental work behind him, and an outlook formed by his seven months in Chile ’s mature metal mining culture.
Any metallurgist awarded the “James Douglas Gold Medal” joins a select group of peer-recognized professionals. As the American Institute of Mining Engineers (AIME) award began just four years after Douglas’ 1918 death, most of the early recipients knew Douglas personally, and of his contributions to metallurgy. For example, Frederick Laist, the first recipient of the medal, worked most of his career with Anaconda Copper Mining Company, where he made his own contributions to copper processing, and worked with hydrometallurgy , advancing the work of Douglas. We could go over the career of each subsequent recipient and find their achievements writing the history of modern metallurgy. However, with time, little by little, Douglas’ work became remote and less relevant to the advances of metallurgy. In the 1920s and even the 1930s, Douglas’ lifework required no reminder to metallurgists; Douglas was a known and respected pioneer. Now, in 2018, at the centenary of his passing, metallurgists know little of Douglas in detail. His work no longer appears in text-books, and it would be an unusual new patent that might reference his ideas (1931 was the most recent reference). Today, the metallurgists completing their material science studies probably assume that the man named in the AIME award must have done something great in metallurgy, but what is was is unclear.
In part, Douglas’ specific work with hydrometallurgy became eclipsed by the overall problems of engineering the science behind hydroprocessing. A key example is found in the evolution of how Edward Dyer Peters, Jr. considered Douglas. Peters published his Modern American Methods of Copper Smelting in 1887 [31]. It went through 15 editions through 1907. The first edition was dedicated to “James Douglas , Jr., whose ability as a metallurgist is only exceeded by his value as a friend, this volume is affectionately inscribed by the author.” The preface went on to thank Douglas for his minute revision and criticism of the manuscript. Peters’ dedication in the 1905 thirteenth edition is worded more broadly, “The author takes great pleasure in renewing the dedication of this book to his friend James Douglas of New York, President of the Copper Queen Mining Company [32].” Peters transformed Douglas, the metallurgist, into an industrial leader. Some 29 years later, in 1933, Douglas is again remembered in the dedication of the AIME Transactions volume on “Copper Metallurgy ” with the words, “To the memory of James Douglas who devoted most of his life to the development of the copper industry and to the well-being of engineers this volume is dedicated.” This 1933 compilation, comprised of 41 articles covering smelting , refining and leaching of copper , carried six leaching articles, none of which mentioned the Hunt and Douglas Copper Process. Arthur L. Walker’s lead article in the same volume covered the “Career and Achievements of James Douglas .” Out of the nine pages, Walker wrote two sentences on Douglas’ patented metallurgy, and made no mention of Chile . Moving ahead another 19 years, George D. Van Arsdale’s dedication in Hydrometallurgy of Base Metals reads, “This book is dedicated to the memory of Dr. James Douglas , pioneer U. S. Hydrometallurgist.”1 Van Arsdale’s book carries the last and final discussion of the Hunt and Douglas Process in a professional publication [39]. At both Queen’s University and McGill University buildings are named for him, and at Queen’s, Douglas Chair is Canada’s first endowed chair in Canadian History. In more recent years, Douglas became one of those “great personages” whose name is on a building or on a prestigious award, but whose ready name recognition has passed with time.
The Hunt and Douglas Copper Process was among first commercial methods crossing the bridge from the chemistry laboratory to an industrial application, from a patented scientific insight to an operating plant. While there were earlier hydrometallurgical efforts, the Hunt and Douglas patent was the first successful chemical process intended to produce metal, as opposed to producing sulphur with metal as an inevitable by-product. The much lower sulfur content of Western Hemisphere copper ores, when compared with those of Spain and Portugal, made the older hydrometallurgical method, the Longmaid-Henderson pyrite process, impractical. When the full history of hydrometallurgy is written, the experiments carried out by James Douglas and T. Sterry Hunt should be near the start of it all. The dead-ends behind the eventual triumphs deserve credit. In the nineteenth century, before the word “chemical” became a negative in popular culture, research “chemists” sought to reduce substances to their core elements. New elements were discovered year after year. In North America and Europe, at the time of the initial Hunt and Douglas patent, there was a flurry of metal extraction experiments and patents based on aqueous chemical solutions [1, 30]. Much of the interest focused on ferrous chloride , observed more than chemically understood. The objective was a commercial process useful for copper sulphide ores under 5%. A process was needed at the mine—transporting all but highest-grade ores to a distant plant was too expensive. What the copper industry required was for someone, somewhere, to solve the problem of how to do in the field, at an industrial level, what was already possible in the laboratory—a cheap process to produce copper metal from low-grade ore .
Methodology
This paper is based on a wide reading of period sources, including thirteen US patents filed between 1869 and 1900 by Hunt and/or Douglas. The Hunt and Douglas patents in Canada, the U.K., Bolivia, Mexico and Chile were also examined. There are dozens of articles about the process, many written by Hunt or Douglas, but also by other metallurgists. The Mining Journal (London), the Engineering and Mining Journal (New York), the Mining and Scientific Press (San Francisco), and the Boletín Minero (Santiago de Chile ) were read, as were numerous English language science and chemical journals from the 1810s through the 1880s. Texts on metallurgy and chemistry from 1818 until 1960 were consulted. The research is part of the author’s forthcoming book: A Beautiful Process: James Douglas Capitalist, and the Fateful Collapse of Chile ’s Nineteenth Century Copper Industry.
US Patent #86,754 Improvement in Processes of Extracting Copper From Its Ore 2
The Hunt and Douglas Copper Process worked. The classic process, patented in 1869, was based on ferrous chloride (FeCl2) as the extraction solvent, and while it remained the centerpiece of Douglas’ subsequent experiments, after 1880 several Hunt and Douglas patents included sulfuric acid (H2SO4). Their six patents over the three decades after 1869 sought to improve the desired reactions and to lower costs. The process, implemented at many mines and custom smelters, stirred the imagination of the industrial press.
The original Hunt and Douglas Copper Process was a vat leaching method for chloridizing “copper oxides”—either naturally occurring or with the sulphur burned off. At each step of the process, solutions moved from wooden tank to wooden tank until reaching the final scrap iron precipitation stage. Soon after the patent for the process was issued, Douglas’ partner, T. Sterry Hunt, began publishing scientific papers on the process [20–22]. As a respected and already much published chemist by 1869, his reports gained scientific attention. The American Chemist, itself a new publication in 1870 and headquartered at the Columbia College School of Mines, carried one such Hunt article; an article representative of how Hunt understood the science of the process. In the American Chemist Hunt writes that the “…peculiarity of the Hunt and Douglas Process is in the solvent used to remove the oxide of copper from the naturally or artificially oxidized ore ” [20]. The process took advantage of chlorine’s high reactivity and strong oxidizing capacity. In other words, Hunt and Douglas engineered a way to remove copper from its ore using a “watery solution” of ferrous chloride (FeCl2) and sodium chloride (NaCl—common salt). The original 1869 patent described what today we recognize as a spontaneous double-replacement reaction between cupric oxide (CuO) and ferrous chloride (FeCl2) yielding as a product cupric chloride (CuCl2) and ferrous oxide (FeO). In turn, a further chloride replacement reaction between metallic iron and the cuprous chloride precipitated out the metallic copper [24].
The observations that led to the Hunt and Douglas Process began with the earlier Whelpley and Storer Copper Process, which Hunt brought to Douglas’ attention [19]. The Whelpley and Storer Copper Process, developed in Boston, underwent field testing at the Harvey Hill Mine in 1867, but never reached the operational stage due to a plant fire at the mine [28]. The decision to try the Whelpley and Storer Process was based on hope. The mine was yielding 4–5% bornite; too low to support heat processing and precluding the previous practice of shipping ore to Liverpool. Facing financial ruin operating the mine single-handed, this “beautiful process” for extraction of the metal seemed worth trying. With the higher grades of oxide ore exhausted, the owners (at the time primarily James Douglas , Sr.) were spending heavily on development work in the hope of finding additional high-grade ore . It was the networking mentioned earlier that united Douglas in the Eastern Townships of Quebec with the Boston team who had stumbled upon unexpected chemical reactions. Whelpley and Storer, in a test of a new shaft furnace design, “…employed a bath of calcium chloride , and into it threw oxidized copper ore and sulphurous acid from a shaft furnace ” [9]. The experiment was intended to develop applications for their line of ore pulverizing machinery and blowers, not the shaft furnace design or the final bath to cool the now oxidized copper . To their surprise, the process promised a way to extract copper metal from sulphide ore below the 5% threshold—seemingly both efficient and economical. After the fire destroyed the field test plant at Harvey Hill, and during the rebuilding, Douglas experimented with other solvents, as well as re-engineering the Whelpley and Storer design. Douglas took interest in the ferrous chloride chemical reactions. Under Hunt’s guidance, Douglas pursued a better understanding of his observations and conducted further experiments. The result was the Hunt and Douglas Copper Process, US patent number 86,754. While it was developed at Harvey Hill, the first operational plant built to further test the Hunt and Douglas Process was in Tiltil, Chile , at the mines of the Invernada Mine Company [3]. The company faced the same problem as at the Harvey Hill mine—exhaustion of high-grade surface oxides.
Van Arsdale concluded that “…the cuprous chloride was held in solution by excess of either ferrous chloride or sodium chloride brine.” The copper was then leached by filtration and precipitation , “…thereby regenerating the solvent, ferrous chloride ” [41]. The 1869 Hunt and Douglas Process relied on precipitation as their extraction method, and only changed to electrolysis with the last two patents (1896 and 1900).
By the time James Douglas received the final Hunt and Douglas patent in 1900 the copper industry had relegated the many “humid” alternatives to a niche corner in the metallurgist’s toolbox [12, 17]. After decades of experimentation and field trials ferrous chloride seemed nothing more than a blind alley—Van Arsdale called it an “indifferent solvent for copper ” [41]. Over the decades Douglas gave more attention to the precise temperature of the brine, but never seemed to vary from their specification for a neutral solution. Notwithstanding their improvements, the necessary benefits of non-selective mining methods and large-scale operation lay ahead, as were precision grinding and sorting methods [41]. After the turn of the century, copper hydrometallurgy was overshadowed by the other hydroprocessing technology—froth flotation . With flotation concentration methods operational, the urgency for a hydrometallurgical method faded. In the years after Van Arsdale’s book was published, the Hunt and Douglas Copper Process went unmentioned. For example, in 1960 Forward and Warren published a survey of wet methods of extraction of metal from sulphide ores, including a review of old chloride and chlorine applications. Their oldest reference to prior usage of ferrous chloride is the 1882 processes of Doetsch and Froehlich [13, 18]. In his 1953 book Flotation , A. M. Gaudin observed one of the consequences of flotation , “With the lowering grade and increasing complexity of the ores being mined about 25 years ago, and the impossibility to effect suitable recoveries by gravity concentration, hydrometallurgy loomed as the dominant ore -treatment scheme for low-grade ores. But the development of flotation has arrested the growth of leaching ” [15].
Language and Atomic Weights
Language is the greatest obstacle to our precise understanding of the Hunt and Douglas Process. The patentees wrote many articles about their process and necessarily relied on the chemical nomenclature of the day. However, this was a time of rapid scientific development. Along with the discovery of new elementary substances and competing classification schemes, each year brought new understandings of the characteristics of known elements and their compounds. Even though copper had been studied more than other elements, the understanding of the underlaying difference between cuprous and cupric copper remained unexplained. Terminology evolved and words once commonplace began to lose meaning. With time, older terms faded and ceased to be used. Over the last half of the nineteenth-century a degree of scientific bilingualism was necessary amid false cognates and increasingly obscure terms—these were decades lacking awareness of electrons, protons, and neutrons. Much of the intellectual struggle of chemists in the time of 1869 Hunt and Douglas’ concerned developing a consensus the terminology to describe observed reactions.
Of consequence, formulas and equations could not but contain errors by today’s standards until the matter of atomic weights was sorted out. It was only in 1869 that Dimitri Mendeleev published his ideas for systematically organizing the elements in a table based on atomic weight [37]. There were at least five other chemists conceiving their own “periodic tables” and putting forth their own “improved” terminology. Scientific debates of the 1860s included the usefulness of such notions “atom” and “molecule.” In turn atomic weight was the key to sorting out the ratios in which elements combined. Measuring the combining power of elements, until the 1870s, took the form of measuring “equivalent weights.” Hunt’s position in the debate over the fundamentals was to question the very concept of a smallest particle—that is, Dalton’s atomic theory. Only today is Hunt’s case for “continuous matter” coming back as a way of thinking about matter [40]. As Hunt was already an internationally recognized scientist when their first patent was granted, it was his name that gave their process credibility and visibility. Of course, Douglas had no reason not to follow Hunt’s chemical thinking, and language.
Formula and terminology comparison chart
Modern molecular formula | Modern ionic formula | Latin system names | Stock system names | Hunt and Douglas [25] formula | Hunt and Douglas [25] patent | Hunt (1869) scientific copper article | Other Hunt and Douglas [20] terminology | Hunt and Douglas [25] promotional booklet |
|---|---|---|---|---|---|---|---|---|
Cu2O | Cu2+O2− | Cuprous oxide | Copper (I) oxide | Cu2O | Oxides of copper /red | Cuprous oxyd | Suboxide | Dinoxyd of copper |
CuO | Cu2+O2− | Cupric oxide | Copper (II) oxide | Cu2O2 | Oxides of copper /black | Oxidum cuprosum | Protoxide | Protoxyd of copper |
CuCl | Cu+Cl− | Cuprous chloride | Copper (I) chloride | Cu2Cl | No term used | Cuprous chlorid | No term used | Protochlorid of copper |
CuCl2 | Cu2+Cl2− | Cupric chloride | Copper (II) chloride | No formula used | Dichloride of copper | Cupric chlorid | No term used | Dichloride of copper |
FeCl2 | Fe2+Cl2− | Ferrous chloride | Iron (II) chloride | FeCl | Protochloride of iron | Ferrous chlorid | Iron dichloride | Protochloride of iron |
FeO | Fe2+O2− | Ferrous oxide | Iron (II) oxide | FeO | Ferrous oxyd | Ferrous oxyd | No term used | Hydrated ferrous oxide |
Fe2O3 | Fe22+O32− | Ferric oxide | Iron (III) oxide | F2O3 | Ferric oxyd | Ferric oxyd | No term used | Ferric oxide |
FeOCl | Fe3+O2−Cl− | Iron oxychloride | Iron (III) oxychloride | No formula used | Oxychloride of iron | No term used | Oxychloride of iron | No term used |
NaCl | Na+Cl− | Sodium chloride | Sodium chloride | No formula used | Chlorid of sodium | Chlorid of sodium | Common salt | Chlorid of sodium |
In 1876 Hunt and Douglas still referred to protoxide of copper , but had moved on to using dinoxyd for copper (I) oxide (Cu2O) rather than suboxide. See Table 2. The molecular formula they used in 1876 for copper (I) oxide was accurate, but was wrong for copper (II) oxide for the reason of misunderstood atomic weight, as discussed above. Yet it seems they understood the changing consensus over weights following the 1869 publication of Mendeleev‘s periodic table. In their 1876 booklet on their process, Hunt and Douglas note, “the reactions between protochlorid of iron and the oxyds of copper are thus expressed as chemical symbols, using… the older notation, in which Cu = 31.75, Fe = 28, Cl = 35.5, and O = 8” (emphasis added) [25]. In the end their audience was made up of working metallurgists, and they decided that it was better to communicate in terms their non-scientific audience were accustomed reading.
One more point needs to be considered about the 1869 process. As mentioned before, chemically the process was a success; that is, the reactions Hunt and Douglas describe happened and could be replicated. Copper metal was extracted. The problem with their process, and all humid processes at the time, was commercial not scientific. The one and only justification for moving from heat-based smelting to a wet or humid process was to lower production costs. The expense of fuel for processing copper ore under 5% was generally, at the time, more than the value of the metal. The Hunt and Douglas Process provided a hope for profitably working low-grade copper . This is the reason most North American observers considered it revolutionary, and several generations of metallurgist kept at the engineering.
The 1869 Hunt and Douglas Patent—A Metallurgist’s Description
On January 11, 1869 Hunt and Douglas filed their initial United States patent application from Montreal. By current standards the patent award came rapidly, less than a month later, on February 9. They termed their “humid process” an improvement, as it was a variation on existing laboratory and industrial knowledge. They claimed as their main invention the use of ferrous chloride —calling it protochloride of iron —as a solvent to convert copper oxides into a soluble solution. They considered their invention a regenerative process; the double replacement reaction not only created cupric chloride , but oxychloride of iron . They claimed in their patent the use of sulphurous acid to decompose the oxychloride of iron and to restore the original ferrous chloride .
As their original patent lacked formulas or an equation for the reactions they described, they conveyed their process with the nomenclature of the day used be metallurgists; the terms with roots in the eighteenth-century Lavoisier system. Today, when reading their descriptions and mineral equations it easy to be adrift as to what exactly they were doing. Lacking accurate theory, they had no way to explain with precision the outcomes. The following selection is from the second paragraph of the 1869 patent—refer to Table 2 for assistance in following their language. The bracketed formulas are in the modern format.
For the extraction of copper ores by this process it is necessary that it should be in the state of protoxide [CuO], or suboxide [Cu2O], or some compound of these oxides… The pulverized and naturally or artificially oxidized ore are then digested with a watery solution of protosalt of iron , with or without the addition of an earthy or alkaline chloride . We prefer the neutral protochloride of iron [FeCl2]… By the action of a solution of protochloride of iron [FeCl2] on the oxides of copper [CuO & Cu2O] these are converted into dichloride of copper [CuCl2], which is readily soluble in concentrated solutions of earthy or alkaline chlorides—such as common salt [NaCl]. At the same time the iron separates from the solution as an insoluble oxychloride [FeOCl] [24].
The power of these reactions at an industrial level could not help but excite anyone who anticipated access to the world’s huge deposits of low-grade ore , which at the time had no value for lack of a commercial process.
The 1869 Hunt and Douglas Patent—A Scientific Description
When ferrous chlorid [FeCl2] in solution with chlorid of sodium [NaCl] is heated with a sufficient quantity of cuprous oxyd [Cu2O], the whole of the iron is precipitated as ferric oxyd [F2O3], mingled with metallic copper [Cu], while cuprous chlorid [CuCl] remains in solution. Experiments made with an excess of ferrous chlorid [FeCl2] show that one third of the copper is reduced, while two thirds are dissolved as dichloride [CuCl2]. This reduction may be effected directly by ferrous oxyd [FeO]; if to a solution of cuprous chlorid [CuCl] in chlorid of sodium [NaCl], we add hydrated ferrous oxyd (FeO(OH) · H2O) recently precipitated by an alkaline base and still suspended in the liquid, it is at once converted into ferric oxyd [Fe2O3], with precipitation of metallic copper .
At this stage of hydrometallurgy Hunt and Douglas’ experiments were trail blazing. In the original process, and in Hunt’s AAAS paper, pains were taken to explain how to make ferrous chloride —there was no supplier to order from.
Douglas’ 1895 Cantor Lecture in London
In May 1895 Douglas delivered four Society of Arts (London) Cantor Lectures on “Recent American Methods and Appliances Employed in the Metallurgy of Copper , Lead , Gold and Silver .” His final lecture in this prestigious annual series covered “The Humid Metallurgy of Copper and Metallurgy of Lead .” He starts with his observation that humid methods had not much been practiced in the United States as there were no deposits of pyrites such as in Spain and Portugal. When he turned to the Hunt and Douglas Process he stated, “In our first method, we took advantage of the reaction pointed out by Meyer, in 1862, between ferrous chloride and cupric oxide, resulting in the production of cuprous and cupric chloride . The insolubility of the latter necessitated the addition to the chloride of iron of a solvent of the cuprous chloride , such as common salt” [9]. The way he spoke of his process revealed that he understood it was a step forward, but that it never fulfilled the revolutionary impact they hoped for back in the late 1860s.
He made clear his view that “…one reason for its limited applicability is the difficulty of separating silver from the mixed solution” [9]. The trouble with the first process was its retention of any silver present in the ores. In the 1874 improvement silver is left undissolved in the residue from the ore , but now the solution was vulnerable to contamination with arsenic . The 1880 improvements sought to isolate other metals from the cuprous chloride . By 1887 the aim was to better deal with both silver and arsenic . Douglas dedication to experimentation and the search for a commercial humid process culminated in his 1896 and 1900 patents for extracting copper from a solution by means of electrolysis. He had worked on such methods since the late 1870s, and finally found a procedure that satisfied him. It may well be that Douglas, at the Phoenixville, Pennsylvania, Chemical Copper Company site, operated the first functioning plant for electrolysis as an extraction method for copper . This was not a full commercial plant, but an experimental one used to perfect methods.
Douglas’ Graduate Seminar on Copper Mining—Chile 1871
The eight months James Douglas worked in Chile at the Invernada Mine Company are literally missing pages from his biography and from the history of copper metallurgy [28]. It was in Tiltil that Douglas first applied what he learned in Quebec about roasting ore and using solvents to extract copper from low-grade copper ore . While he brought new ideas to Chile , it was there that he began to think about where the industry was headed. Consequently, to fully understand the James Douglas of Arizona and Wall Street, it is necessary to consider what he learned in Chile .
On February 21, 1871, Douglas began the experience that changed his understanding of metal mining, of non-ferrous metal mining. On that day he left the British steamship Panama, anchored in Valparaiso Harbor, to meet with Juan Stewart Jackson. Jackson, a Chilean banker and mine investor, brought Douglas to Chile to oversee installation of the “revolutionary” Hunt and Douglas Copper Process at the Invernada mine camp. As related earlier, Jackson found out about the process through his networking with Arthur Lewis, the Liverpool copper broker. Once Jackson was convinced that the process was worth the risk of investment, he wasted no time in patenting the process in Chile and organizing a new mine company to work a group of mines with the same low-grade problem as at Harvey Hill. The new company bought out Jackson’s friend, Henry Thorner, who had been trying to work the mine single-handed. The limited-liability shares were purchased by a who’s who of merchants and bankers in Valparaiso—all sharing Jackson’s belief that they were gaining access to the seemingly unlimited quantities of low-grade copper ore in the country’s mountains.
In his meeting with Jackson, Douglas was assured that if the experiments at the mine bore out his promises, he, Douglas, would “go home with a fortune” [6]. Jackson, more than anyone else at the time, grasped the implications of the process. The Chilean thinking of the day held that when a mine hit low-grade copper sulfide , it was a death sentence. Now with the Hunt and Douglas Process at hand, Jackson saw low-grade sulfides as an opportunity. Later that year, while the plant at Invernada was nearing completion, Jackson wrote to Chile ’s president, José Joaquín Pérez, requesting an extension of the patent protection. Jackson explained to Pres. Pérez that to understand “…the value of this process and the great advantages it will bring to our country, keep in mind that there are huge quantities of copper tailings of between 4 and 5% in Chile that until now have been considered without value, and that there are immense mountains of low-grade minerals that presently are left unexploited for lack of a low-cost method to benefit them” [27]. As president of the Invernada Mine Company, and a shareholder, the process would not only benefit him personally, but as the patent agent, he stood to earn a commission on all low-grade ore production. By September 1871 new applications of the process were already in the works based on the promising early results at the Invernada mines [42]. At Invernada, the ore was primarily bornite, along with chalcocite and chalcopyrite —Douglas termed it “4–5% purple sulphuret.”
Today, the low-grade copper reserves of the Chilean Andes Mountains are well established. In 1870, the hope and promise that the day had arrived when the copper industry could exploit these “low-grade minerals ” was a powerful attraction for the group of 27 Invernada investors. At the request of Jackson, Douglas remained in Chile longer than originally planned and only departed on September 11. During his seven months in the country he visited many mines and spoke with the leading mine owners and engineers of the day. He was Canada’s first international mine consultant. While he failed to earn significant financial reward from his process in Chile , instead, he came home with something more valuable—a deep understanding about where copper mining was headed. He learned in Chile that mining, copper mining, could be a business, and not a speculation as he observed it in Canada. Of greater importance for his career, he learned that it was not the quality of copper ore that mattered, it was the quantity. In one of his first post-Chile articles on copper , he wrote, “If copper is to be mined profitably it must be found in large quantities. The ore must not necessarily be rich, but there must be plenty of it” [7].
Over the next two decades Douglas was the Chile expert for the North American mining press. He wrote about Chile and copper markets, always assessing Chile ’s copper productivity . As Chile faded as a competitor, so did interest in Chile ’s mines. Douglas never went back to Chile , but stayed in touch with Jackson by mail. As Douglas began to advise young mine engineers and metallurgists he thought of Mexico and Chile in years ahead; he told them to “learn Spanish” as a professional skill.
Conclusions
Douglas’ leading reputation as a metallurgist was built on three decades of pioneering hydrometallurgical experimentation. He had no way to know what he did not know. Yet he obviously knew what was revealed by the early experiments he carried out with Hunt. What Douglas and Hunt lacked was an underlying theory—a limitation tied to the chemical knowledge of the time. Their early work was based on erroneous atomic weights, but that did not matter much as they proceeded on what they observed. They could replicate what they saw. Douglas put what he and Hunt learned into patents as a business matter. All through his career he advocated open sharing of technology accompanied by payment of fees when a patented technology was adopted [10]. Hunt, for his part, used their research to publish scientific papers. Today, Hunt would be considered a geochemist. Douglas’ example inspired subsequent generations of researchers trying to fulfil the dream of a humid process that was both scientifically perfect and profitable. A handful of metallurgists kept at it—seeking to engineer what still seemed as a good idea [17, 18, 41].
Perhaps Edward Peters best caught the eventual dark mood of metallurgists about “wet methods” when he wrote in 1907, “To the inexperienced observer there is something very attractive in these wet, or chemical, methods. As a copper ore usually consists of a very large amount of worthless material (gangue) and a very small proportion of valuable metal, it would seem much more reasonable to employ an agent which acts solely upon the valuable metal and leaves the worthless portion untouched…. Costly experience has taught us that the results obtained in the wet treatment of ores on a commercial scale are frequently not so favorable as we might infer from the laboratory tests” [34]. Peters’ caution continued, “I desire, however, to point out that a class of processes [hydrometallurgy ] …has been given up in almost every case in which it has been tried in the United States…” and it “…is not one in which to seek the means of starting a new mining and metallurgical enterprise…” [34].
Today, Douglas is remembered by the AIME “James Douglas Gold Medal,” whose citation recognizes “distinguished achievement in nonferrous metallurgy, including both the beneficiation of ores and the alloying and utilization of nonferrous metals. Dr. Douglas, founder of Phelps Dodge Corporation and twice President of AIME, was also an AIME Honorary Member. He was an industrialist, a mining engineer, a metallurgical engineer and a noted inventor of metallurgical equipment.” The only omission in the AIME citation is Douglas’ parallel career as a writer, and perhaps a more explicit mention of hydrometallurgy , but this is understandable as the award began at a time when wet methods seemed a dead-end. Finally, in considering the Hunt and Douglas Copper Process as one of the earliest efforts to solve the low-grade copper ore problem, we must necessarily take note of the daring Chilean visionaries whose saw the future of copper mining, and who invested in the world’s first commercial hydrometallurgical plant up the Maritatas Canyon in Tiltil, Chile .
Had James Douglas not had his imagination opened by what he saw and learned in Chile , his western consulting and his ideas about Arizona’s possibilities might have been much narrower. Credit is due to Douglas’ mentors in Chile , and Juan Stewart Jackson in particular, just as a generation or two of metallurgists in the United State owe credit to their mentor, James Douglas .