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By A. G. Roach

This paper deals with a plant built under joint agreement between the Canadian and United States Governments to supply the strategic mineral, corundum, at a time when African production was dwindling and war demands still increasing. The operation began in September 1944, retreating the tailings from a former mill by gravity methods, and is still in production (Sept. 1946). In 1942, when it became apparent that South African production would be insufficient to meet mounting wartime requirements of corundum, a survey was made of Canadian sources of the mineral, at the request of the Foreign Economic Administration of the U. S. Government. The investigation' indicated that the quickest and cheapest supply would be obtained by reworking the tailings deposit at Craig-mont, Ontario. Sampling of the dump by Canadian Government engineers revealed that 125,000 tons of tailings, averaging 2.96 pct corundum, was available for retreat-ment. Ore-dressing tests on representative samples of the deposit were conducted by the writer in the laboratories of the Industrial Minerals Section of the Department of Mines and Resources at Ottawa; and gravity concentration on tables was indicated as the most suitable method of treatment. Decision to proceed with the project was deferred until May 9, construction was begun on May 18, and tune-up operation of the plant begun on Sept. IS, 1944. Corundum—Its Properties and Uses Corundum is an oxide of aluminum having the formula Al2O3. Its outstanding characteristic is its great hardness; 9 in the Mohs scale. In this respect it is second only to the diamond. It usually occurs in barrel-shaped crystals in nepheline syenites and other feldspathic rocks deficient in silica. It has a specific gravity of 3.95 to 4.1 and is insoluble and infusible. In color it ranges from white, through red and green, to black. Ruby and sapphire are gem varieties of corundum. Corundum is supplied to industry as closely graded grain.= The coarser roducts (10 to 24-mesh) are used largely for snagging wheels in the steel-castings industry, while the finer grades (from 70-mesh down to flours) find a wide application in the polishing of lenses and for other uses in the optical trade. All sizes of corundum grain are in close competition with synthetic abrasives such as carborundum and alundum. In some fields of application the artificial product is superior to the natural grain but not in' all. The shape of the particle and its behavior under conditions of actual use determine its sphere of employment. The United States is the largest 'Onsumer of corundum, annual consumption in peacetime approaching 3000 tons; during the war this figure was roughly doubled. During the years 1902 to 1913, the bulk

Jan 1, 1948

THE compiler, or author, of the Probierbücblein is not known, and the date of its first printing is uncertain. It was obviously not written by an assayer who wished to give a coherent description of his craft for the instruction of others; this was left for Biringuccio first to do. It is easy to believe that originally the Probierbücblein was a random collection from various sources of information useful to an assayer, probably gathered by one of the profession for his own use. It must remain a matter of speculation whether this was shown to a printer, who recognized the opportunity to turn an honest penny and made an inept attempt to give the manuscript the appearance of a coherent account by writing a preface and arranging the various items in somewhat logical sequence, or whether the assayer him- self started this job and was prevented from finishing it. That some sections of the book, especially near the be ginning, present an almost continuous story, while others are chaotic in their arrangement; that several paragraphs are printed more than once in different places; that there are paragraph headings, for which the text was never written, or lost, followed by irrelevant information-all this seems evidence of a job unfinished and points to a publisher's offering for the public's quick money. The demand must have been brisk, for metal working was a profitable profession, and the jeweler who was working with metals but did not care to become completely trained in assay methods would jump at the chance of acquiring easy knowledge. Even the great Agricola has whole sections obviously plagiarized from the Probierbücblein. Neither Biringuccio nor Ercker shows any direct influence, though they and all subsequent metallurgists will in some degree be affected by

Jan 1, 1949

By O Pasca, B Hogg

Consistent slag blow end point detection remains one of the challenges in the Peirce-Smith converters at Mount Isa MinesÆ Copper Smelter. Under blowing results in foaming on copper blow and carry forward of oxide skims to the anode furnace. Over blowing results in high copper losses to the slag. Both present safety issues and contribute to lower copper production. The end points of the slag making phases are assessed by inspection of a bar sample. A bar sample is a thin accretion layer that adheres to a steel bar when it is inserted into the tuyere while the converter is blowing. This method is biased and subjective, so there is heavy reliance on operator experience. The Semtech Optical Process Control (OPC) system was installed in early 2002 for converter slag blow end point detection. Initial plant trials did not improve all aspects of converter operations, and uptake by operators was poor, so the system was not used. In early 2005, the Semtech OPC system was re-visited and another short trial was conducted to evaluate the permanent use of the system for slag and copper blow end point detection. During this trial, the Semtech OPC method was found to be superior to bar sampling for slag blow end point detection. The implementation and refurbishment of the Semtech OPC system has resulted in plant improvements and given a better insight into converter operation during blowing. Oxide skim generation carried forward to the anode furnace has been shown to decrease with increasing compliance with Semtech OPC. Some of the expected improvements to converter operation were not found to be significant. Semtech OPC is now well received and utilised by converter operators. Individual paper available only. Not included in book or CD ROM Proceedings.

Jan 1, 2005

By J. L. Stuck

Geological investigation and research have contributed greatly in making industrial minerals the basis of an important industry in the state. North Carolina contains a wide variety of industrial minerals and rock. Mica, feldspar, kaolin, halloysite, talc, pyrophyllite, silli-manite, and spodumene are used to illustrate the progress being made. IN a previous paper1 an attempt was made to indicate the importance of industrial minerals in North Carolina and the wide variety of such materials present. The present paper is concerned with geological investigation and research which have made industrial minerals the basis of an important industry in the state. Geological mapping has gone through three stages in North Carolina during the present century. The first stage is represented by excellent reports of which Corundum and the Peridotites of Western North Carolina,2 Volume I, now a classic, is representative. In this report, a geologic map of the western third of the state is shown on a scale of 10 miles to the inch. The next stage is represented by folios" of the U. S. Geological Survey published between 1902 and 1932. Most of these contained 30 min quadrangle maps on a scale of 2 miles to the inch. The third step is represented by reports prepared during the past 10 years which contain geological maps4 on scales varying from 500 ft to 1 mile to the inch, while many mine maps have been prepared on scales varying from 20 to 150 ft to the inch. As the scale on which geological mapping has been done has decreased, the amount of information secured has increased. Pratt and Lewis did excellent work on the peridotites of western North Carolina, but their maps lacked details. Keith and others added

Jan 1, 1952

By T. Lane Carter

Before describing the experience with the Chinese on the Rand and the work they have accomplished, it will be necessary, first, to give a brief account of labor-conditions in the Transvaal since the war, and then to show how the necessity of importation of labor arose. As is well known, the Transvaal mines are run on the dual system of labor—that is, the rough work is done by colored laborers under the superintendence of white men. From the start of mining operations in South Africa there has been the cry of shortness of native labor, due in great measure to the failure of Kaffirs to work continuously in the mines. While he works, the Kaffir is a satisfactory laborer, but his period of service is short, averaging about nine months. People unacquainted with the Kaffir have maintained that, by offering a higher wage and better accommodation, better results would be obtained from the native workers, but an increased wage simply aggravates the trouble. The Kaffir's wants are few. While at work Be spends little of his money, and before long has sufficient capital with which to buy wives and become a gentleman of leisure. Doubling the wage of the Kaffir means that he acquires a competency in half the time, so that his period of service is correspondingly reduced. In 1899, before the war, there was always a cry about the scarcity of Kaffir labor. The highest number of natives at work was in July and August, 1899, when nearly 100,000 were employed. At the outbreak of hostilities the Kaffirs were scattered far and near, many doing well during the war by working for the military authorities. On the resumption of mining operations on the Rand a serious mistake was made. Based on past experience, it was argued that if the whole industry decided to start anew with

Jan 1, 1909

By L. M. Barker

THE New Cornelia Branch of the Phelps Dodge Corporation is at Ajo, Pima County, Ariz. It is at the southern terminus of the Tucson, Cornelia and Gila Bend Railroad, which connects with the Southern Pacific Railroad at Gila Bend, Ariz., approximately 43 miles to the north. HISTORY Early history of the Ajo district has been related by A. W. Allen1 and by T. A. Rickard.2 Briefly, steps looking to the large-scale development of the ore body were instituted as early as 1912. This work culminated in the equipment of the property for open-pit mining by steam shovels. Ores initially mined carried economic amounts of copper carbonates as the principal copper-bearing mineral. Treatment methods developed for the extraction of the copper content involved leaching and a 5000-ton leaching plant was constructed and placed in operation in early 1917. Description of methods and equipment employed in this plant has been given by A. A. Tobelmann and James A. Potter.3 As exhaustion of the carbonate ore body neared, and mining operations exposed an adequate tonnage of sulphide ores, a 5000-ton concentrator was constructed for their treatment. That plant has been described by H. Kenyon Burch.4 Construction was completed and the plant was placed in operation in early 1924. Changes made in the original plant to improve practices and increase production will be the subject of subsequent paragraphs of this paper.

Jan 1, 1939

By H. A. Baxter

THE Eustis concentrator is located about nine miles southwest of Sherbrooke, on the main line of the Quebec Central railway. The concentrator is served by a side track parallel to the main line, and all supplies for both the mine and mill are delivered at the mill yards. The concentrator treats 250 tons of copper-iron ore daily by preferential flotation, whereby, first, the copper sulphides are floated and the iron pyrite is depressed, and, second, the iron pyrite is reactivated and floated, resulting in an iron pyrite concentrate and tailing, the latter going to waste. During 1934, 71,709 tons of ore were treated, averaging 3.712 per cent copper and 32.1 percent iron, with a small amount of silver and a trace of gold. The recovery was 93.77 percent of the copper, and 70.43 percent of the iron as iron concentrate. The copper concentrate produced averaged 25.623 percent copper and the iron-pyrite concentrate averaged 42.13 percent iron and 49.173 percent sulphur. HISTORY The first mill at the Eustis mine was built in 1904 (1). For a few years previous to this rime, some jigs had been operated to concentrate the fines from the mine, the coarse ore being hand-sorted. Both the fines and sorted lump ore were shipped to acid plants. The building of the mill was based on test work carried out by Professor Robert H. Richards at the Massachusetts Institute of Technology. The method of concentration consisted in careful classification in a Richards classifier, which made six different sized products. These products went to Wilfley tables, where a concentrate, middling, and tailing were made. The middling was returned to the rolls. Crushing was done by a jaw crusher and two sets of rolls, resulting in a screen size of about five-mesh.

Jan 1, 1936

By D. Lemieux

A gold bearing pyrite concentrate was treated at the pilot scale for the extraction of gold. Mineralogical analysis of the concentrate identified gold to be mainly present in the form of a solid solution in pyrite. This gold distribution resulted in a poor extraction yield of 55% by direct cyanidation. A piloting campaign including an oxidative pre-treatment by roasting in a fluid bed was followed by treatment with halogens for gold extraction has led to a gold extraction yield of 96.5%. Sulphur removal during the oxidation was very efficient at >99.5% and gold extraction by the halogens was completed within a 1 hour contact time. The piloting was performed on a 300 kg sample and uses a diluted solution of hypohalites as the oxidizing agent for gold extraction. Sulphuric acid was injected in the reactor during the halogens treatment to lower pH to 2. The diluted solution of hypohalites (1-3%) was generated by electrolysis during the piloting campaign in a membrane-less electrolysis cell. The extracted gold was recovered over activated carbon in column and the gold depleted brine was treated for impurities removal and recycled for further gold extraction. With the recycling of water and brine, the regeneration of hypohalites and with a barren solid that is inert and stable, the Nichromet Extraction technology is a green process where the protection of the environment does not preclude profitability.

Aug 1, 2013

By L. M. Barker

THE New Cornelia Branch of the Phelps Dodge Corporation is at Ajo, Pima County, Ariz. It is at the southern terminus of the Tucson, Cornelia and Gila Bend Railroad, which connects with the Southern Pacific Railroad at Gila Bend, Ariz., approximately 43 miles to the north. HISTORY Early history of the Ajo district has been related by A. W. Allen1 and by T. A. Rickard.2 Briefly, steps looking to the large-scale development of the ore body were instituted as early as 1912. This work culminated in the equipment of the property for open-pit mining by steam shovels. Ores initially mined carried economic amounts of copper carbonates as the principal copper-bearing mineral. Treatment methods developed for the extraction of the copper content involved leaching and a 5000-ton leaching plant was constructed and placed in operation in early 1917. Description of methods and equipment employed in this plant has been given by A. A. Tobelmann and James A. Potter.3 As exhaustion of the carbonate ore body neared, and mining oper-ations exposed an adequate tonnage of sulphide ores, a 5000-ton con-centrator was constructed for their treatment. That plant has been described by H. Kenyon Burch.4 Construction was completed and the plant was placed in operation in early 1924. Changes made in the original plant to improve practices and increase production will be the subject of subsequent paragraphs of this paper.

Jan 1, 1939

By L. H. Hart

Because of a widely recognized association between breccia pipes of one form or another and many important copper deposits, conditions under which breccia pipes develop have been of great scientific interest for many years. Since these phenomena first attracted attention, many theories have been advanced to explain their origin. This is not unexpected, since it is likely that they have been formed by and under a wide range of conditions. Moreover, the entire subject is confused by the fact that the term breccia pipe is applied to a wide variety of occurrences. To discuss any part of the subject intelligently, therefore, it is necessary to start with definitions of the terms used. In their discussion of the Toquepala deposit, Richard and Courtright have carefully defined the terms they have used in their presentation of a very logical geo- logical history of Toquepala breccias. This is a real contribution, as there is no reference in the literature known to the writer where the history of a series of breccia pipe epochs, confined essentially within one channelway, may be read with the degree of certainty that appears to be possible at Toquepala.

Jan 6, 1958

L. E. WEMPLE, St. Louis, Mo. (written discussion *).-Mr. Stone refers to cadmium as one of the worst impurities in ores used for the production of zinc oxide for pigment purposes, because it is very volatile and its dark brown oxide and bright yellow sulphide both have strong coloring powers so that small fractions of 1 percent. injure the whiteness of the oxide. Numerous tests have recently been made by the American Zinc, Lead and Smelting Co. to determine what effect the percentage of cadmium, as ordinarily present in zinc ores, has upon the color of oxide made from such ores by the usual grate-furnace process. It has been found that while the cadmium is readily volatile and may be detected in the oxide product by chemical analysis, the oxide product is not discolored, but is of a clear white color. Analysis of the 12 leading brands of zinc oxide, French process, lead-free, and leaded grades now on the market for pigment purposes, show them to contain from 0.02 to 0.35 per cent. cadmium, figured as metal. If these proportions of cadmium were present as oxide or sulphide, the percentages would run from approximately 0.022 to 0.40 per cent. in the first case and 0.025 to 0.45 per cent in the latter case. All these grades of oxide are widely used for pigment purposes and are of a clear white color, except the leaded grades, the whiteness of which may be diminished by the lead sulphate. Tests made with admixtures of as low as 0.02 per cent. of cadmium oxide or sulphide to zinc oxide of the greatest hiding power (lead-free

Jan 1, 1918

By R. C. Beckstrom

Russia's first "Petaletka'' has ended. Technically it did not succeed but practically it has been a great achievement in the petroleum industry. Out of the chaos of revolution and civil war Russia has developed her oil industry to second place in the world's production. For 1932 production of crude oil is estimated at 150,000,000 bbl. and refined products at 145,000,000 barrels. Russia has been able to give the petroleum industry every advantage that a government can extend to a fast growing industry. She has obtained all of her property by confiscation. Under government ownership, operation and control, her petroleum industry is not handicapped in any way by state rulings or by unnecessary competition in production, refining and marketing. There are no damage suits resulting from offsetting, flooding, repressuring, laying of pipe lines, building of docks or other necessary work. Russian oil fields2 have been easy to develop and operate. They lie advantageously to transportation for foreign markets. The chief disadvantages have been a lack of credit and technical cooperation, but the former is being overcome by the sacrifice of the people. They go without the comforts of life that all salable articles may be exported for the imports of modern machinery. Modern machinery is fast replacing the obsolete and worn-out equipment. Technical cooperation has been difficult because it has been necessary to train thousands of adults to do technical and mechanical work. Great quantities of pipe, tools and electrical equipment were necessary for the rapidly developing fields and refineries. The supplies have been inadequate and the quality poor. This lack of equipment, along with the untrained technical supervision, has been the cause of the proposed quota falling short. Fig. 1 shows the production for 1931 and 1932. During 1932 a large percentage of the oil was produced in the proven fields of the Caucasus.

Jan 1, 1933

By K. Heindlhofer

ESTIMATES of the "plasticity" of a metal are commonly deduced from three types of test-tensile, torsion and impact. The several results have been more or less at variance, though this disparity has attracted little notice, largely perhaps because they have been expressed in different terms. The discrepancy between the results of the three tests becomes obvious when each is made at a series of low temperatures, for the temperature range within which the "plasticity" of iron largely disappears proves to be very different in the three types of test. The rather abrupt disappearance of "plasticity" of iron within a narrow temperature range cannot be due to any physicochemical change (such as a precipitation) taking place in the material at that time, because the original plasticity is immediately regained when the temperature of the material is brought above the sensitive range. Accordingly this differ-ence in behavior shows that the "plasticity" of a metal depends upon the mode of action of the stresses which produce the deformation, and there-fore upon the method of test. Analysis of the stresses leads to the conclusion that the observed plasticity of a metal is determined by the relation between its resistance to rupture by separation and its resistance to shear (slip), on the one hand, and between the effective normal and shearing stresses on the other; and that the relation between the two resistances does not in general remain constant with change of temperature, and may somehow be altered to some extent by the previous treatment of the specimen. This suggests the view that the results of none of the usual mechanical tests are directly comparable even for a single metal tested at a series of tem-peratures, or for a series of metals at one temperature, because the propor-tion of the total resistance of the metal to the test contributed by the

Jan 1, 1934

By A. R. Laplante

The mineralogy of the Joe Mann mine differs from that of other deposits of the Chibougamau area that are exploited by Les Nines Camchib Inc. It is characterized by very fine first generation gold and very coarse second generation electrum. Successful processing required adjustments of the processing flowsheet, which includes gravity, flotation, and cyanidation. A study of coarse gold liberation in the gravity/grinding circuit is described. Modifications to the flotation circuit and the reconditioning of a small capacity cyanidation circuit are presented.

Jan 1, 1989

By J. M. Toguri, H. Flood

The application of the mass action law to the thermodynamic treatment of metal-slag equilibria is discussed. The consideration of the reactions essentially as ionic exchange equilibria is shown to be both an advantage and an aid for the elucidation of the theoretical treatment. This is illustrated by several examples. In general two different methods of application of the mass action law to metal-slag equilibria have been used by different groups of investigators. These could be called the oxide reaction and the ionic reaction approach respectively. At the recent discussion in the metallurgical section of the I.U.P.A.C. Congress in Montreal, 1961,' divergent opinions prevailed regarding the most rational way of applying the mass action law to metal-slag equilibria. This question is of fundamental importance in the treatment and understanding of theoretical chemical metallurgy. Consequently, the following is an attempt to contribute towards its clarification. As an example, the distribution of iron and manganese between molten iron and slag will be considered. I) THE OXIDE EXCHANGE REACTION APPROACH The equilibrium between iron and manganese between molten iron and slag is frequently formulated as an oxide metal exchange reaction as follows:

Jan 1, 1963

By F. J. Tuck

THE Hayden mill of the Ray Mines Division, Kennecott Copper Corporation, is now equipped with two 9 by 12-ft. rod mills having a daily capacity of 6000 tons of coarse-crushing plant product from the mine. These two mills crush a ¾ -in. product to approximately 19 per cent on 14 mesh, with only one pass through the mills. Each rod mill has taken the place of four sets of 42-in. Garfield rolls with their attendant screens, and is making a product for the fine-grinding department comparable to that formerly made by rolls in closed circuit with screens. The rod mills are lined with wave-type liners of white iron, varying in thickness from 2 to 3 in. The shell and end liners last approximately 600 to 700 days. Manganese-steel lifter bars, 3 5/8 in. thick, are used, spaced about 11 in. apart, and they give a life of 350 to 450 days. Fig. 1 shows the general design and thickness of the wave-type liners and lifter bars; 1 ½ -in. liner bolts are used to fasten the lifter bars to the shell. The shell liners are held in place by the tapered lifter bars. A 3/4-in. wood backing is used between the shell and the liners. The rod-mill scoop has removable manganese-steel lips, which last 250 to 300 days. The scoop proper has shown some wear in spots, and these spots have been protected by rubber bolted over them. Water and milk of lime are added to the elevator feeding the mill, but not enough water to cause a pounding of the rods against the shell. Roughly, the water added amounts to 25 to 33 per cent of the ore. Additional water is added to the mill discharge to facilitate distribution to the classifier bowls in the fine-grinding department. Rods are charged to the mill once every four days, the mill being down about 20 min. for this purpose. Other delays are negligible, and usually are due to a loose liner bolt or possibly power trouble. However, these occasions are extremely rare. In charging the mill, a crane is used

Jan 1, 1938

By F. J. Tuck

The Hayden mill of the Ray Mines Division, Kennecott Copper Corporation, is now equipped with two 9 by 12-ft. rod mills having a daily capacity of 6000 tons of coarse-crushing plant product from the mine. These two mills crush a ¾-in. product to approximately 19 per cent on 14 mesh, with only one pass through the mills. Each rod mill has taken the place of four sets of 42-in. Garfield rolls with their attendant screens, and is making a product for the fine-grinding department comparable to that formerly made by rolls in closed circuit with screens. The rod mills are lined with wave-type liners of white iron, varying in thickness from 2 to 3 in. The shell and end liners last approximately 600 to 700 days. Manganese-steel lifter bars, 3? in. thick, are used, spaced about 11 in. apart, and they give a life of 350 to 450 days. Fig. 1 shows the general design and thickness of the wave-type liners and lifter bars; 1½-in. liner bolts are used to fasten the lifter bars to the shell. The shell liners are held in place by the tapered lifter bars. A ¾-in. wood backing is used between the shell and the liners. The rod-mill scoop has removable manganese-steel lips, which last 250 to 300 days. The scoop proper has shown some wear in spots, and these spots have been protected by rubber bolted over them. Water and milk of lime are added to the elevator feeding the mill, but not enough water to cause a pounding of the rods against the shell. Roughly, the water added amounts to 25 to 33 per cent of the ore. Additional water is added to the mill discharge to facilitate distribution to the classifier bowls in the fine-grinding department. Rods are charged to the mill once every four days, the mill being down about 20 min. for this purpose. Other delays are negligible, and usually are due to a loose liner bolt or possibly power trouble. However, these occasions are extremely rare. In charging the mill, a crane is used

Jan 1, 1939

By F. J. Tuck

The Hayden mill of the Ray Mines Division, Kennecott Copper Corporation, is now equipped with two 9 by 12-ft. rod mills having a daily capacity of 6000 tons of coarse-crushing plant product from the mine. These two mills crush a ¾-in. product to approximately 19 per cent on 14 mesh, with only one pass through the mills. Each rod mill has taken the place of four sets of 42-in. Garfield rolls with their attendant screens, and is making a product for the fine-grinding department comparable to that formerly made by rolls in closed circuit with screens. The rod mills are lined with wave-type liners of white iron, varying in thickness from 2 to 3 in. The shell and end liners last approximately 600 to 700 days. Manganese-steel lifter bars, 3? in. thick, are used, spaced about 11 in. apart, and they give a life of 350 to 450 days. Fig. 1 shows the general design and thickness of the wave-type liners and lifter bars; 1½-in. liner bolts are used to fasten the lifter bars to the shell. The shell liners are held in place by the tapered lifter bars. A ¾-in. wood backing is used between the shell and the liners. The rod-mill scoop has removable manganese-steel lips, which last 250 to 300 days. The scoop proper has shown some wear in spots, and these spots have been protected by rubber bolted over them. Water and milk of lime are added to the elevator feeding the mill, but not enough water to cause a pounding of the rods against the shell. Roughly, the water added amounts to 25 to 33 per cent of the ore. Additional water is added to the mill discharge to facilitate distribution to the classifier bowls in the fine-grinding department. Rods are charged to the mill once every four days, the mill being down about 20 min. for this purpose. Other delays are negligible, and usually are due to a loose liner bolt or possibly power trouble. However, these occasions are extremely rare. In charging the mill, a crane is used

Jan 1, 1939

By R. G. Knickerbocker, W. E. Brown, G. J. Vahrenkamp, M. M. Fine

THE results of a research and development laboratory and pilot-plant mineral-dressing investigation by the Bureau of Mines of the complex copper-lead-cobalt-nickel ores of southeast Missouri are reported in this paper. This investigation, in cooperation with the National Lead Co., showed that separate concentrates of lead, copper, and cobalt-nickel could be made by fine grinding and flotation. An industrial plant built subsequently by the St. Louis Smelting and Refining Div. near Fredericktown, Madison County, Mo., produced such concentrates during the war years. Present commercial production at the mill is limited to lead and copper concentrates, but research to permit economic utilization of the cobalt and nickel values is continuing. The complex sulphide deposits near Frederick-town in Madison County, Mo., have an operating history that dates back to the years preceding the Civil War. Perhaps these operations can best be summarized in terms of output which are given by Tyler: "Previous to 1900, the Mine la Motte Co. shipped cobalt ore to Swansea and in 1903 produced 120,000 pounds of oxide in a Missouri plant. Another cobalt refinery erected in 1906 by the North America Lead Co. at Fredericktown, Mo., operated intermittently until 1910. In 1909 it produced 83,384 pounds of cobalt oxide, 328,403 pounds of nickel, 8,314 tons of nickel-cobalt concentrates, 600 tons of copper concentrates, and 1,353 tons of lead concentrates. This plant was purchased at a forced sale in 1915 by the Missouri Cobalt Co., which produced a certain amount of oxide in 1918 and in 1920 recovered 102,410 pounds of cobalt oxide and cobalt hydrate, valued at $262,810." According to Buehler,2 "The ore, which consists of a complex mixture of the sulphides of cobalt, nickel, copper, lead, and iron, occurs at the contact of the pre-Cambrian porphyry and the overlying Lamotte sandstone and Bonneterre dolomite." The source of most of the cobalt and nickel is siegenite, a member of the linnaetite series of minerals. Its composition is variable, and although the chemical formula may be given as (CoNi),S,, it usually contains both iron and copper. The siegenite is characterized in this instance by an intimate association with chalcopyrite, and to a lesser extent with iron sulphides. Galena, on the other hand, while dis- seminated throughout the ore, is not closely bound to other constituents. Gangue is composed essentially of dolomite and quartz. Petrographic examination showed that fair liberation of sulphides and gangue could be attained at — 100 mesh. Complete liberation of micronsize inclusions, particularly of sulphides in each other would not have been possible at —400 mesh. Beneficiation Studies Many samples of the southeast Missouri ore were tested, but most of the work was confined to five samples of churn drill cuttings weighing 15 tons. The samples were reportedly representative of five sections of the deposit and were tested individually and as a composite. Only the results of the tests on the composite, which contained 1.28 pct lead, 2.03 pct copper, 1.06 pct nickel, 0.87 pct cobalt, 3.57 pct iron, 15.4 pct lime, and 23.9 pct silica, are presented in this report. In view of the rather complex and intimate association in the mineralogical composition of the ore, flotation was the logical choice in the selection of a beneficiation process. Other mineral dressing unit operations were considered as an adjunct to flotation, but none were beneficial. Many tests were made on these samples to determine the flotation characteristics of the mineral siegenite. As a result of this work, it was noted the siegenite was intermediate in floatability between chalcopyrite and galena on one extreme and iron sulphides on the other. The difference in floatability between siegenite and the iron sulphides was not very great and, in general, the same reagents that depressed pyrite and marcasite would also, in slightly larger quantities, depress siegenite. This tendency for siegenite

Jan 1, 1952

Infacon 74 Members are reminded of the International Ferro-Alloys Congress that is to take place in Johannesburg between 22nd April and 1st May, 1974. The Congress is being held jointly by the National Institute for Metallurgy, the Ferro Alloy Producers' Association of South Africa, and the South African Institute of Mining and Metallurgy. Correspondence and enquiries should be addressed to The Secretary, Organizing Committee, INFACON 74, Private Bag 7, Auckland Park 2006. The gold deposits of the farms Lisbon and Berlyn in the Eastern Transvaal by v. c. H. R. BRERETON. Published in the Journal November 1973. AUTHOR'S CORRECTIONS The following amendments should be made.

Jan 2, 1974