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By A. J. Kraemer, H. M. Thorne

The following account of oil-shale operations in Australia is based upon infor- mation obtained by the authors while visiting Australia from September 15 to October 7, 1947, supplemented by published data, and augmented by analyses of samples of oil shale and its products at the Oil-shale Research and Development Laboratories of the Bureau of Mines at Laramie, Wyo. The primary objective of the authors' trip to Australia was to obtain, first hand, information regarding the equipment and methods used by National Oil Proprie- tary, Ltd., at Glen Davis, New South Wales, in mining oil shale, extracting oil from it, and refining the shale oil. This company was operating the only oil-shale plant that had been active in Australia since 1945. The plant comprised an oil-shale mine, 104 modified Pumpherston (Fell) retorts in 2 batteries, a hele refinery, and a 3-inch gusoline pipeline to the railroad loniing terminal t Sun Junction, 30 miles away. There were, also, the usual and necessary any uralities, such as a power house, mechanical shops, offices, and laboratories One Information regarding the company's operations was wance because of its bear- Ing upon the synthetic liquid fuels program of the Bureau of Mines, pursuant to the Synthetic Liquid Fuels Act of April 5, 1944 (30 U.S.C., 321-325, as amended). objective of the Bureau's program. In accordance with the maniate of the Act, is to furnish American industry cost and engineering data necessary for the development of synthetic-liquid fuel industry, and an obvious means of obtaining some of these data is to learn how oil shale is being mined and retorted and how shale oil is re- rined in countries where these operations have been conducted on a plant scale for many years. The authors spent 2 weeks at the plant of National Oil Proprietary, Lt., at Glen Davis, and were afforded every opportunity to obtain letailed and specific information regarding all aspects of the company'a operations.

Jul 1, 1951

By E. LaRocque

"Long term contracts requiring delivery of 6,000,000 pounds of U308 per year to its customers have made it necessary for Denison Mines to expand its milling capacity from 7,100 tons per day to 15,000 tons per day.Previous papers (1) and (2) described the old leaching and product recovery practice. The flowsheet briefly includes a crushing and grinding circuit, sulphuric acid leaching in a Pachuca plant, liquid-solid separation with wash thickeners and two-stage drum filtration, concentration and purification by moving bed ion exchange followed by two-stage precipitation to produce an ammonia yellowcake.No. 1 Shaft ore, about 4,000 tons per day, will be processed through the truck dump into the old crushing and grinding plant and through the old leaching plant. Ore from Stanrock (No. 3 shaft) will be hauled by truck and also processed through the truck dump as No. 1 shaft ore. Beginning in 1982, ore production from Stanrock will gradually increase until 1985 when some 3,000 tons per day will be milled from the source.A new 8,000 ton per day circuit was designed and constructed to increase the milling capacity to 15,000 tons per day. The new circuit is separate from the old one except that it coins together for the precipitation and tailings neutralization sections of the plant. The feed to the new plant will be from No. 2 shaft.The flowsheet is much the same as the old plant with the exception of the grinding circuit and the ion exchange plant. A semi-autogenous grinding (SAG) plant, unique in the Elliot Lake area, has been installed rather than the conventional crushing and grinding plant; the ion exchange plant is the stationery bed type.This paper describes the major equipment installed for the expanded grinding and hydrometallurgical plant."

Jan 1, 1982

The use of coal as a fuel causes air, pollution in; a number of different forms, and in nearly all stages of its, handling, preparation, storage, use and-disposal of its residue. First let us consider the handling of coal. As shipped, particularly to large utilities, it is run-of-mine bituminous made up of large chunks as well as pulverized particles. Because it 'is in an open car or barge, it is subject to the action o winds and the small particles may be blown around adding to the-particulate load in the atmosphere. Mien un¬loaded from the barge or car, there is again an opportunity for the wind to blow the fine particles around. All of us I am sure have seen a barge at the dock of a utility plant being unloaded by a clamshell bucket. This, after grabbing its load from the barge, lifts it some 60 or 70 feet and, then drops it on a conveyor, which carries the coal to a storage area.

Jan 1, 1964

The placer gold industry has experienced a roller-coaster history incorporating four major boom eras. The first, 'hand-methods' boom arose in the mid-19th Century from application of an old idea in new places around the globe. The subsequent hydraulic mining, bucket dredging, and 'hydraulic excavator-portable plant' booms each arose from application of new ideas in old places around the globe, ie in places where gold had been found during earlier booms. The new ideas that heralded the second, third and fourth booms were all significant advances in excavation technology. These enabled the industry to target the known deposits that were too deep, too wet, too small, or too low-grade for recovery by earlier boom methods. Relatively few new deposits or new deposit styles arose from the 'history book' exploration approach, so the number of known deposits to which each of the boom methods were applicable was limited. Consequently, the first three booms were each followed by significant periods of industry decline, and the fourth boom is currently waning inNew Zealand. Further decline is not inevitable and can be avoided by changing to a knowledge-based exploration approach similar to that adopted by the hard rock gold industry in the 1970s. Such an approach could easily herald the next placer gold boom.   Most of the relatively coarse, easily won alluvial gold in proximal and medial reaches of the active placer systems is gone. However, a substantial alluvial gold resource remains in the distal reaches of active systems, and in ancient placers formed onshore and on the continental shelf during previous sedimentary cycles. The resource in these deposits probably exceeds the total New Zealand placer production to date. Successful development of these placers requires application of robust geologic models for the formation and distribution of the placers through time, and advanced exploration technology that has not been used before in New Zealand. Nevertheless, the knowledge and technology required to explore and mine these deposits is available now. Many of these deposits contain a large proportion of problematic gold types that are difficult to recover with the commonly used gravity technology without sustaining significant losses. Despite advances in recovery technology in last few years, too much emphasis is placed on the incorrect assumption that gold size is the primary control on recovery efficiency. Other gold particle parameters, especially particle shape, exert a much greater control on whether gold will be saved or lost to the tails, and must be considered in the design of recovery technology and configuration of recovery circuits.

Jan 1, 2003

By Joseph Jensen

MANY fields have been zoned by nature with shales and intermediate waters between oil zones. Limitations thus imposed have been the basis on which the field was developed. In contrast thereto, in the Ventura Avenue Field, nature proved more generous. Always expecting to find such similar limitations, operators drilled deeper and deeper into the oil zone without finding any distinctive shale bodies other that the Gosnell shale and only one intermediate water, which became the point below which the final water shut-off of each well was made. Thus, on top of the structure, about 3300 ft. of oil-bearing zone has been penetrated below this intermediate w9ter-a distance of 4000 ft. below the Gosnell shale. At first it seemed that the greater the penetration in the zone, the better the well. The error of this assumption became evident

Jan 1, 1930

By R. A. McIvor, R. Levac

"The Stobie No. 7 shaft, 14 ft diameter, double- drum skip hoist, was installed at the INCO Limited Frood Stobie Complex in 1942. Figure 1 shows the hoist layout. The hoist was originally equipped with babbitted journal bearings on the main drum shaft and pinion gears. In 1990, the hoist was modernized with a new braking system, two new 2000 hp D.C. drive motors, a thyristor armature supply and a PLC control system. The new drive motors were connected to the drive pinion gears with a gear type flexible coupling. The pinion gear journal bearings were refitted during the refit in 1990 as the existing babbitted bearings showed signs of wear. The pinion gear journal bearings had always run warm and had external cooling applied during the warm summer months. Figure 2 shows the journal bearings on the pinion shaft. The skip hoist main bull gear and two pinion gears were replaced in 1997 because of cracked bull gear spokes. New drive couplings were installed on the pinion gears and the pinion journal bearings were modified to allow some self-aligning properties to try to reduce the heating and wear on the babbitt. The modifications did not significantly reduce the heating problems and a decision was made in the spring of 1998 to convert the bearings to self-aligning, anti-friction-type bearings.The traditional roller bearings used on double helical pinion drive gears in hoist applications has always been double-row spherical roller bearings due to their high load-carrying capacity and misalignment allowances.Unlike single helical gears, double helical arrangements do not exert axial thrust on the pinion gear bearings, therefore, both bearings in the pillow blocks must float easily with any pinion displacement. Drum misalignment, thrust bearing end play and a multitude of other influences causes continuous axial displacement of the pinions when in operation. This constant displacement or “hunting” of the pinion gear to maintain its centre on bull gear often exceeds the axial clearance limits of spherical roller bearings thus resulting in a continuous sliding motion of the bearing outer rings against the housing seats. With time, the housing fit eventually wears, creating an out-of-round condition for bearing housing (maximum allowable cylindricity tolerance is IT4/2). When this happens, the pillow block housings must be replaced or re-machined to specification. Premature bearing wear and overheating will occur if a housing out-of-round condition is encountered."

Jan 1, 2001

By R. W. Hodder

"Archean lode gold deposits of both vein and chemical sedimentary types typically have major enrichments of certain rare elements, including Au, Ag, As, Sb, B, W, Se, Te and Bi, coupled with low or negative enrichments of the more abundant and mobile base metals, Cu, Pb and Zn. On the other hand, in massive base metal sulphide deposits Au, Ag, Cu, Zn and in some instances Pb are all enriched by a factor of 200 to 2000 t:'Jf'1pared to background and there is no large separation of gold relative to the base metals.The fluids from which gold was precipitated in veins were at temperatures of 320 to 480°C, at lithostatic pressure, had significant C02, and Na """" K; whereas the fluids which generated base metal deposits were at 250-300°C, at hydrostatic pressure, had C02 < < H20 and Na > > K.Many lode gold deposits are characterized by K, C02 and Si additions to their enveloping rocks, whereas base metal deposits typically have a fixation of Fe, Mg, Si and S in footwall rocks. Lode gold deposits may also have a relatively large halo of low-temperature oxidative, sadie spilitization in enclosing volcanic rocks, where seawater has later streamed into cooling stocks or flows that have initially acted to focus gold mineralizing fluids along thermal contraction fractures. The submarine environment is one hydrologically appropriate for the mixing of two initially independent hydrothermal systems, and the blending of their separate characteristics. Hence, lode gold and base metal massive sulphide deposits appear to be products of two distinctly different crustal and hydrological regimes. The former involves a high-temperature, high-pressure discharge of fluids which probably were generated during dehydration accompanying burial and progressive accumulation of volcanic-sedimentary sequences, with an additional influence of marine water in the near-sea-floor environment. The latter represents thermally driven convection of ocean water at lower temperatures and under hydrostatic conditions.Auriferous fluid systems with only minor base metal content could plausibly be generated during dehydration accompanying burial and metamorphism, when the water-to-rock ratio is low and halogen availability is limited by crustal abundance (- 60 ppm Cl). These two factors may constrain the uptake of the abundant base metals into fluids, but the solubility of rare elements is not constrained by limited fluid; and preferential uptake of Au along with other rare elements may be promoted if such elements compete more successfully for the limited halogens than the base metals, and/or have an alternative complexing agent such as CO or C()j-."

Jan 1, 1982

By W. C. Holliman

Commercial production of synthetic rubber in the United States became a reality in 1931 when E. I. duPont de Nemours, Inc., announced the manufacture of Duprene, a synthetic rubber made by polymerizing r chloroprene. Duprene was later improved and reintroduced as neoprene. Since 1931 other synthetic rubbers and rubberlike materials have been announced and are now produced commercially or are in the pilot-plant stage in the United States. These include Thiokol, Buna S, Perbunan, Koroseal, Vistanex, Flamenol, Ameripol or Hycar, Chemigum, Butyl rubber, and Flexon. None of these is synthetic rubber in the strict chemical meaning of the word synthetic, as none is identical in chemical structure with natural rubber. However, all possess some of the physical properties of natural rubber, and in addition usually have some outstanding property not found in natural rubber that makes them superior for certain uses. Because of these superior qualitites, a considerable demand had arisen for synthetic rubbers before the present emer¬gency, although the price was several times that of natural rubber.

Jan 1, 1943

By CHARLES M. A. STINE

THE value of chemical research has been so thor¬oughly demonstrated in the last few decades that the general public has become "research-conscious" to an extent which allows the advertising agent and publicity man to make use of research as a selling point in his advertising campaigns. We thus see the advertisements of concerns in the most varied industries stressing the research which is back of their products. The reason for this "research-consciousness" of the general public. is primarily that the products of research have increasingly engaged public attention and have. revolutionized our daily life. When we. reverse the flight of .time and imagine ourselves-in the century previous to our own, we find that we are .without the automobile, the radio, the improved telephone and electric light, refrigerated transportation, the airplane, X-rays, and many other things now taken for granted. A generation ago we find gloomy prophets foretelling the certain over-population .of the world within a few decades and an insufficiency of food due to lack of the fixed nitrogen which is now so plentifully ours.

Jan 1, 1930

By G. O. Allard, A. Gobeil

The Chibougamau area is the eastern segment of the MatagamiChibougamau greenstone belt. The Archean rocks of the area consist of two mafic-to-felsic volcanic cycles ( Roy Group) overlain by a sedimentary-volcanic sequence (Opemisca Group). The Roy Group volcanics are intruded by many coeval and comagmatic differentiated gab bro sills. The Supracrustal rocks of the Roy Group and Opemisca Group have been folded about north-south axes, refolded isoclinally about east-trending axes and metamorphosed to the greenschist facies. The same lithologies have been identified east of the Grenville Front at amphibolite grade. The first volcanic cycle consists of 3000 metres of porphyritic pillowed basalts and comagmatic gabbro sills (0batogamau Formation) overlain by a thin sequence of felsic pyroclastics, porphyritic dacites, and iron formation (Waconichi Formation). The Dore Lake Complex is a sill-like layered complex intruded in the upper part of the Waconichi Formation. The second cycle consists of 3600 metres of pillowed basalts and gabbro sills (Gilman Formation) overlain by a volcanosedimentary assemblage less than 1000 metres thick (Blondeau Formation). The Cummings Complex consists of the Roberge sill (dunite and peridotite) at the base, the Ventures sill (gabbro) and the Bourbeau sill (leucogabbro and quartz ferrodiorite) at the top. It is emplaced within the Blondeau Formation. The Opemisca Group sediments and minor porphyritic K-rich andesites (Stella, Hauy, and Chebistuan Formations) form narrow belts preserved in the synclines of the area. The Proterozoic rocks of the Chibougamau area consist of conglomerates, arkoses, and argillites with dropstones of the Chibougamau Formation. North of Chibougamau, the Mistassini Basin forms an elongate northeast-trending basin filled with sediments of the Mistassini Group. Conglomerates, sandstones, argillites, dolomites, stromatolitic dolomites, and iron formation are the principal sediments within the basin.

Jan 1, 1984

By Zay Jeffries

AN acute current shortage of copper, with the prospect that conditions may become worse, indicated by Office of Production Management information. Present estimates of copper requirement for defense indicate that nearly all the available metal will be required in the future for this purpose. Severe dislocations are, expected, but the objective is to distribute the copper available for civilian use in such a manner as to minimize these dislocations. The advisory committee on metals and minerals has been asked for a suggestions which may be helpful in meeting this situation.\

Jan 1, 1941

1. Domestic Production and Use: In 1983, 12 companies operated 27 primary aluminum reduction plants, with 4 firms accounting for 65% of production. Washington, Oregon, and Montana accounted for 35% of the production; Indiana, Kentucky, Maryland, New York, Ohio, and West Virginia 35%; Tennessee, Alabama, South Carolina, and North Carolina 14%; other central States 16%. Based on published producer prices, output of primary metal in 1983 was valued at over $5.7 billion. Aluminum consumption by 25,000 firms was centered in the East Central United States. Packaging accounted for an estimated 37% of domestic consumption in 1983, transportation 19%, building 17%, electrical 9%, consumer durables 8%, and other uses 10%.

Jan 1, 1984

By D. Harrington

Dust diseases are much before the public at present, but little reliable information on the subject is readily available to the layman; even those rated as experts usually have a more or less theoretical conception of these diseases, their causes, remedies, and prevention. Until recently little attention has been given to prevention, and the usual attitude of the engineer, upon whom the main reliance for prevention ultimately must devolve, has been to let "sleeping dogs lie" or, more definitely, to "let well enough alone." However, the "laissez faire" attitude no longer is tenable; in the past few years numerous conditions have caused those engaged in industry, including mining, to study the subject with a view to ascertaining the facts upon which to formulate remedial measures, primarily preventive. This bulletin is an attempt to assemble information in convenient form on effects of breathing dusts, largely in the mining and allied industries. The literature on this subject is so extensive that no attempt has been made to include all published material or all types of dust diseases but only to assemble some of the more outstanding data on several aspects of the subject, especially with reference to silicosis.

Jan 1, 1937

By Pat McCarran

WHEN this Government was founded, the framers of the Constitution wrote into that instrument a provision that Congress should "coin money and fix the value thereof;" and the Constitution prohibits making anything but "gold and silver" lawful money. So silver is written into our basic law. Shortly after President Washington took office in 1789 the Congress passed the first Mint Act, setting up the U. S. Mint. In that Act, signed by President Washington on April 2, 1792, the weight of the American dollar was fixed, and it was provided how much silver should be contained in a silver dollar and how much gold should be contained in a gold dollar. It was decided that 371 1/4 grains of pure silver was to be the standard dollar of America. That standard with respect to the pure silver content of the dollar has never changed.

Jan 1, 1947

By Alan K. Burton

Massive increases in the productive capability of open pit nines after World. War II were in a large part made possible by the introduction of ever larger trucks and the supply of a seemingly bottomless ocean of inexpensive and readily accessible oil. Over a period of about 25 years, a variety of technological developments permitted a tenfold truck payload increase, from about 32 tonnes (35 tons) to 320 tonnes (350 tons). There is no, doubt that this was a remarkable achievement resulting in impressive benefits of scale as well as the ability to control what would otherwise have become an intolerable traffic congestion problem in today&apos;s large open pit mines. It became fashionable and economically possible during this time to mine large quantities of low grade material and to tolerate very high stripping ratios. As tine has gone by and as easier to get at and higher grade deposits have been depleted, ore grades have tended to decline while stripping ratios have increased. The alternative to reduced revenues has been an ever increasing demand to step up production which in turn has led to a continuing demand for ever larger and larger trucks. While a larger truck has had the effect of reducing the cost of the operator per unit of material moved and of reducing traffic congestion, it has not specifically addressed the subject of fuel cost.

Jan 1, 1981

By K Ringwood, J Cummings, C J. Moran

The development of a water accounting framework that enables consistent and contextual reporting of minerals operationsÆ water use, represents a key sustainable development objective that many Australian minerals companies have committed to. A future water accounting framework will require: key terms and definitions for water metrics for use in the Australian minerals industry that are consistent with the wider water sector, a suite of metrics representing key components of an operationÆs water balance, a calculation method for some of the metrics, and a reporting protocol. This paper presents the methodology that was used to derive these four components. Existing accounting frameworks were reviewed and key terms and definitions that were consistent with current regulatory requirements and voluntary approaches were proposed. A calculation methodology was developed to obtain some of the key indicators and variables that cannot be easily measured directly (eg water loss through evaporation). The adopted terms and definitions typically require a combination of empirical and estimated data. To test the proposed definitions and calculation methodology, values for water metrics were derived for eight sites, selected to test a variety of commodity and biophysical situations. The proposed framework and definitions could deal with the specific situations selected as case studies. The associated calculation methodology produced complete accounts at various levels. Some elements of the accounts could be directly checked against available data and simulations. The framework captured well variations in the reuse efficiencies; reuse efficiency could even vary for similar processes. It is concluded that this preliminary accounting framework provides a consistent language and metrics for quantifying and communicating water management, both at the intersection of the site with the surrounding landscape (through detailed reporting of site inputs and outputs) and within operational activities. Using this consistent framework for quantifying and documenting water use within an operation will provide a platform for compiling and comparing minerals industry water use with other sectors. This may support benchmarking activities within regions or companies and help demonstrate leadership amongst water users in water resource stewardship. The approach presented here is applicable to a wide variety of mining and processing activities, and biophysical environments, and following a period of stakeholder engagement and third party review, is being refined as a first step towards developing nationally consistent water use reporting for the Australian minerals industry.

Jan 1, 2009

By G. M. Bond

Reduction of the emissions of greenhouse gases, such as CO,, is currently the subject of extensive research. A novel strategy is put forward here, based on a biomimetic approach providing accelerated deposition into carbonate form for long-term sequestration. It offers the advantages of a process that: does not require concentration of CO, from flue gases; could potentially be used in an on-site scrubber to provide a plant-by-plant solution to reducing CO, emissions; is an environmentally benign procss with an environmentally benign product; and is based on readily available, low-cost reagents (except perhaps the catalyst).

Jan 1, 1999

By Keith Harris

The U.S. economy grew moderately in the second quarter of 1985 with real gross national product (GNP) recording a seasonally adjusted annual growth rate of 2.0%, up from the 0.3% growth of the previous quarter but significantly below the 7.1% growth of the second quarter of 1984 (table I). Personal consumption expenditures grew 5.3%, with purchases of durable and nondurable goods rising 7.4% and 5.1 %, respectively; nonresidential and residential fixed investment--the two components of fixed investment--grew 11.8% and 5.6%, respectively; and Government spending rose 3.6%. However, these gains were tempered by a major decline in the growth of business inventories (from $19.1 billion to $8.3 billion) and the continuing growth of the net export deficit (from -$28.4 billion to -$33.3 billion). While the high value of the dollar compared with other currencies has been a major cause of the expanding trade deficit, its value, as measured by the monthly Federal Reserve Board (FRB) multilateral trade-weighted dollar index, has declined over 17 index points from its February peak to 140.94 in July. The July dollar value was still high historically. The rate of inflation, as measured by the fixed-weighted price index for GNP, remained low at 4.1%, down from 4.3% in the first quarter, and employment continued to grow at a rate sufficient to keep up with new additions to the labor force. Civilian unemployment has remained steady at 7.3% over the past 6 months. Industry Statistics The FRB recently revised its index of industrial production and changed the base year from 1967 to 1977,1/ The revised total index shows a 0.1 % higher annual growth rate between 1967 and 1984 than the previous index. In the slower growing or declining industries, such as metal mining, primary metals, and fabricated metals, however, downward revisions in the indices and rates of growth have occurred. The previous and revised annual rates of growth between 1977 and 1984 for several of the sectors of interest to the mining industry are shown in table 2.

Jan 1, 1985

By Hu Harries

WE RECENTLY completed a study for a client, who is an applicant to export gas from the Province of Alberta, on the effects of gas export on Alberta&apos;s economy. This study was part of the client&apos;s application ?before the Conservation Board, and, no doubt, some of you are familiar with it. Submissions by other applicants in earlier hearings before the Board and before the Royal Commission on Energy, as well as claims made by parties opposing export, have also brought forward a number of other opmwns regarding possible economic effects. Ali of these studies have been on a piecemeal basis. They have dealt with particular aspects of particular applications, and only indirectly and by inference with the overall question of gas ex-port. We have prepared this paper to review the overall picture and ex-amine, as far as time permits, all sides of the question. While the paper is entitled Economic Effects of Gas Export on Alberta, we felt that the area considered should in-elude northeastern British Columbia, not only because Westcoast, the first major gas export project, is essentially a northeastern B. C. project, but because this area has historically been, from the point of view of economic, if not of political, geography, part of Alberta. In this paper, when we talk of export, we mean export from the Province or, in this case, from Alberta plus northeastern B. C. Sales to other parts of Canada have exactly the same effect on the economy of this area as l1ave sales to the United States, provided, of course, they are made on equal terms.

Jan 1, 1958

By G. C. McLachlan

Two papers dealing with Noranda&apos;s milling operations have already been presented. The first1 of these covered the initial metallurgical problems connected with the treatment of the ore, while the second2 described the development of the mill from a 500-ton unit in 1928 to one with a daily capacity of 3000 tons less than six years later. At the time the second paper was written the equipment whirh had been installed to bring the mill capacity up to 3000 tons was being tuned into production and for this reason, though each step had previously been tested by a large-scale pilot operation, it was thought advisable to withhold metallurgical data until any starting-up difficulties had been overcome and anticipated requirements fulfilled. These requirements called for an improvement in gold recovery without any lowering of the previous ratio of concentration, and the pages that follow deal with the methods by which this result was obtained. An idea of the character of Noranda concentrating ore will be gained from an inspection of the following mineralogical analysis of the ore treated by the mill during 1933: MineRal Content Mineral ConteNt Chalcopyrite, per cent..... 6.8 Silica and silicates, per cent............ 18.3 Pyrite, per cent........... 22.1 Gold, native and as telluride, oz. per ton 0.15 Pyrrhotite, per cent....... 51.5 Silver, probably as argentite, oz. per tou 0.35 Magnetite, per cent....... 0.5 Thesr figures, which are typical, show that over 73 per cent of the ore treated consists of pyrite and pyrrhotite. Determirnation of the proportion of unrecovered gold associated with each of these minerals was therefore of primary importance in developing a suitable method for improving gold recovery. As pyrrhotite is magnetic, this information was obtained by making magnetic sorting tests on samples of the mill tailing and screening the material thus segregated. This showed that the magnebtic material finer

Jan 1, 1935