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By J. L. Green

Virginia-Carolina Chemical Corp., in its Florida Operations, uses both roller mills and ball mills in dry grinding of phosphate rock. The roller mills have been in operation since 1954 in the Mining Department. The ball mills were installed and put in operation in 1960 in the Harding Concentrate Superphosphate Plant. The roller mills in the Mining Department are used to grind phosphate rock for outside customers. This involves short notice orders of varying grinds, grades and types of rock. The ball mills grind phosphate rock for use in V-C's own phosphoric acid and concentrated superphosphate plant. These mills grind generally two types of rock for one grind. In 1959, a 10% speed-up was made in the operating speed of the roller mills. This paper deals with the operational gains and resulting cost savings which evolved from this speed-up, and compares the present operations of the roller mills and of the ball mills in grinding phosphate rock. In January 1959 it was decided to determine the feasibility of reducing the grinding cost on the roller mills, per ton of rock ground, by speeding up the mill 10%. At this time, one mill was completely reconditioned so it would be in top condition. Extensive tests were then run both before and after the mill speed-up to determine the resultant cost savings. These tests showed that, due to this 10% speed-up, the mill capacity was increased approximately 20% and grinding power costs per ton were reduced approximately 10%. Table I shows the results of these tests. Each test run actually represents several of the same type rock and grind, averaged together. Each test run lasted approximately three hours. The validity of these runs has been confirmed by subsequent operation in grinding over 1,000,000 tons of phosphate rock. Accurate records have been kept on power consumption and repairs as well as tons produced. Two types of feed rock were used for the tests — pebble phosphate rock and flotation phosphate concentrate rock. The pebble phosphate rock size is approximately 80-90% plus 20 mesh. The flotation concentrate phosphate rock size is approximately 15% plus 20 mesh and 95% plus 100 mesh. The same two types of rock feed were used for all the test runs. Test Nos. 1, 2, and 3 were run at the original mill speed of 85.5 rpm on the vertical shaft. Test No. 1 was run with a feed of high grade flotation concentrates; the desired fineness attempted was 70% passing 200 mesh. Tests No. 2 and No. 3 were run with a feed of low grade pebble. Test No. 2 was run for a desired fineness of 70% passing 200 mesh. Test No. 3 was run for desired fineness of 50% passing 200 mesh.

Jan 1, 1963

By D. Brosnahan, J. Gathje

Newmont Metallurgical Services (NMS) recently acquired a Scanning Electron Microscope (SEM) with a JKMRC/FEI Mineral Liberation Analyzer (MLA). With the MLA software package, raw particle image and X-ray data can be converted into particle mineral maps and bulk and liberation data can then be calculated for minerals of interest. This type of quantitative mineralogical data can then be used for a wide variety of applications. Ore characterization with MLA can be carried out for existing or processing plants in development. MLA characterization of laboratory test products provides valuable liberation information that assists the research metallurgist in better planning and developing process treatment options for various ore types. This paper describes the use of MLA characterization in a copper flotation test program where the use of various testing options for arsenic depression was being evaluated.

Jan 1, 2007

The principles of geometry and trigonometry are so continuously used by mining engineers for the purpose of accurately and intelligibly recording their measurements, that the writer is prompted to lay the following cursory remarks upon mine surveying before the members of this Institution in the hope of eliciting a free interchange of opinion upon details of this interesting branch of the profession. He proposes to deal with surveying only so far as it concerns the mining engineer, not to intrude upon the domain of the professional surveyor, and, in this instance, to discuss more especially that which may be termed the mechanical, rather than the mathematical side of surveying.In the latter part of the eighteenth century and the beginning of the present one, the usual underground surveying equipment in the English metalliferous mines, consisted of a magnetic needle in a fiat square wooden box of about 9-inch sides, a two-foot rule, a long cord, aud a stool, upon which to place the needle and box. The operator took his bearing by sending his assistant with the end of the cord as far in a straight line as the length of the cord would admit.On its being drawn that he held its end in one hand and placed the side of the compass-box against it with the other, and noted the bearing thus found either by a book entry, or by ticking it off with a piece of chalk on the board the compass lay in. He then measured the cord with a two-foot rule. It is needles to say that with these appliances the accuracy of the results were open to question, and mining surveying was not unduly popular.In the present day, engineers have the advantage of using instruments brought to such a state of perfection, and of employing such an exact system of underground surveying, that inaccurate work must usually be attributed either to lack of care, or lack of ability in the operator.

By A. L. Engel

The Bagdad-Chase copper-gold mine south of Ludlow, Calif., was visited by an engineer of the Bureau of Mines in July 1955 to determine the mine's status of activity and to obtain a bulk sample for metallurgical testing. The deposit was discovered in 1903 and has been worked intermittently. It has a production record of about 273,000 tons of ore. The first production of about 150,000 tons was treated in a cyanide plant 2 miles west of Barstow, Calif. The extraction of gold was not satisfactory because of the presence of copper minerals. Since 1910 the ore has been shipped to various smelters in Arizona and California for use as a flux.

Jan 1, 1957

By Hannan J. C

In New South Wales, development applications for major coal mining proposals are determined by the Minister for Planning and Environment and applications for mining leases and other mineral titles are dealt with by the Minister for Mineral Resources. The environmental conditions placed on the development consent, the coal mining lease and the approvals and licences under the pollution control legislation, amount to a substantial component of any new project's planning and commissioning considerations.An outline is presented of the framework within which various approvals are granted and conditions for environmental management are imposed upon mining projects. The principles and concerns, as perceived by the regulatory authorities, on which the majority of approval conditions are based are also outlined.No attempt has been made to analyse the extent to which these principles or standards are achieved in practice, nor to discuss the degree to which some of the conditions are achievable with the current status of technology and economics in the coal industry.

Jan 1, 1987

By Thomas M. Barczak

Roof support systems are necessary to provide stable mine openings and much research has been conducted to design a variety of roof support systems that will function in various manners to ensure that stable ground conditions are achieved. Despite these advancements in technology, mistakes continue to be made in the evaluation and/or installation that significantly degrade the support capability or lead to erroneous determinations of support expectations. The purpose of this paper is to discuss misconceptions about how roof supports perform and factors that impact their performance. The goal is to present practical information that will assist mine operators and engineers in selecting, installing, and evaluating roof support systems properly, and help them to avoid mistakes that can lead to erroneous expectations and potentially catastrophic results that may lead to roof falls. The paper is limited to a discussion of secondary roof support systems and powered roof supports such as longwall shields.

Detailed petrographic analyses of coal seams from the Newcastle, Illawarra, and Lithgow Coal Measures were made for a number of localities for each of twelve seams. From these analyses characteristic standardprofiles were derived for each seam. Two broad types of profile were found; one in which vitrite-poor and vitrite-rich layers alternate, and another in which there is a steady decrease in vitrite from the base to the top of the seam. From comparison of the petrographic profiles it was concluded that the Great Northern Seam in the Northern Coalfield is a possible equivalent to the BulIi in the Southern; and likewise the Fassifern to the Balgowni...

Jan 1, 1967

By D Barclay, S Mercer, S Wright

Mine water management is often an afterthought in mine planning processes and can introduce significant risks to projects when studied as a stand alone component at a later stage in the mine design. Incorporation of a mine dewatering and pore pressure dissipation strategy in the early stages of mine planning is imperative in order to minimise constraints on the production schedule, to match designed pit slopes and maximise project value for an open cut mine option such as Olympic Dam. A risk-based mine planning approach was adopted during the project selection phase study whereby water management was introduced into mine planning, scheduling and the development of an operational strategy. Hydrological and hydrogeological studies and outputs were successfully integrated into the various iterations of the mine planning cycle during early selection phase to manage the potential water management risks associated with pit slope depressurisation and access to dry working conditions during rapid advancement of mining phases.An extensive network of vibrating wire piezometer sets and long-term depressurisation testing characterised aquifer conditions and demonstrated that hydraulic connectivity exists within the geological profile due to the presence of structures and resource drill holes which enhance vertical connectivity. This connectivity, along with underdrainage from mining activities contributes up to 100 m of depressurisation in low permeability units.A pit dewatering strategy incorporates the mine planning schedules and accounts for operational constraints as to the location and development of the dewatering wells, storages and pipelines. Numerical modelling generated a range of likely pit inflows and dewatering requirements with the average initial dewatering discharge likely to be 150 L/s and reduce quickly to 50 L/s after five years, depending on the premine schedule.Coupled hydrogeological and geotechnical assessments were also carried out as part of the mine planning cycle and indicate that successful dewatering will go a long way to reduce the pore pressures within key geotechnical units during the rapid mining phase where around 300 m of cover sequence is stripped in five years. However, the residual storage in the primary aquifer and the residual pore pressure in underlying low permeability units will need to be dissipated (in-pit horizontal holes) as the pit floor advances. Pit slope design angles are sensitive to depressurisation and dewatering and up to 70 per cent depressurisation of key geotechnical rock units are required. Whilst an accelerated program of aquifer dewatering supported by lithostatic unloading should drive rapid depressurisation in the lower permeability units, intervention is anticipated in key geotechnical units such as the Tregolana Shale and volcaniclastics. The extent of induced drainage will ultimately depend in part upon the mining rate and geotechnical stability requirements. Practical operability testing addressed the potential for operational constraints to mine depressurisation activities such as congestion and mining schedule development within the pit and identified that depressurisation drilling can be achieved even with reduced access availability. Mine operations and planning groups established design criteria and considered the likely inoperable periods following rainfall events of seven to 14 days to manage the base surge and minimise impact on production. In-pit surface water management options to minimise operational disruptions during and after significant rainfall events were estimated used a stochastic approach.

Jan 1, 2009

By P R. L Browne

Study of geothermal systems in the Taupo Volcanic Zone (TVZ) has significantly advanced our understanding of the processes of epithermal mineralisation. The three main lessons learnt are: 1. knowledge of their chemical anatomy; 2. precious metal transport and deposition; and 3. hydrothermal alteration zoning. These are described in the context of ore formation and exploration.

Jan 1, 1997

By R. Guardia, J. Hoskins, E. Claros, Y. Kamiya, R. Ramirez, J. Dalenz, P. Fernandez, E. Ilgren

Crocidolite is a well known causative agent for mesothelioma. Studies have shown that the pathogenicity of the fiber from different mines varies considerably and it has been postulated the parameter that appears most likely to account for this variation is fiber width. Epidemiological studies have shown that ‘thin’ fibers from mining areas of Western Australia and the Cape Province, in South Africa are associated with a high mesothelioma risk while exposure to ‘thick’ asbestiform amphibole fiber of the same fiber type are associated with little or no mesothelioma risk. This study is concerned with ‘thick’ Bolivian crocidolite but similar findings also probably explain the paucity of mesotheliomas in the Finnish anthophyllite, South African amosite and African Transvaal crocidolite mines. The findings from the present study suggest the incidence of mesothelioma in the three major cities of Bolivia is not significantly elevated above background even though Bolivian crocidolite has been used for the past 60 years commercially and residentially in all three cities. Although some cases of mesothelioma may have been missed due to a failure to reach hospital or a shortened natural lifespan, mesothelioma generally occurs after the age of 50, we cannot tell precisely the extent to which these were confounding. We suggest the most likely explanation for the lack of mesotheliomas despite the large populations at risk from the long and extensive residential and commercial use of crocidolite containing products, is related to an increased fiber width distribution and a concomitant reduction in the ‘Stanton fiber size’ fraction.

Jan 1, 2012

By S. M. M. Safvi, A. Jowett

Small-scale continuous flotation tests are described in which the influence of 1) pulp density and 2) feed rate on the rate of flotation are investigated. The results provide further evidence of first-order kinetics for flotation and indicate that tests at different feed rates provide a particularly simple method of determining rate constants. Flotation kinetics are discussed in general terms. Over a period of many years numerous research workers have studied the rate of recovery of valuable materials from flotation pulps with a view to deter-mining the mechanism of the froth flotation process. Froth flo ation is fundamentally a collision process involviug at some stage collision and then mutual attachment between air bubbles and mineral particles. It is possible to draw analogies therefore between the flotation process involving mainly macroscopic particles and the ordinary processes of chemical reaction kinetics involving collisions between atoms, molecules and ions. By adopting this analogy we may postulate a general equation representing the kinetics of the flotation process: -dC/dt =K.CC ,Aa (1) The rate constant, K, will be a complex function involving reagent concentrations, particle and bubble sizes, induction times and no doubt flotation cell design. However, these are factors which can be kept constant in any series of experiments, permitting investigation of the exponents a and c, which determine the order of the reaction occurring in flotation. The various research investigations carried out so far have all aimed at evaluating a and c and in the majority of cases only since the concentration of air has usually been kept constant in a series of tests, so that a relationship of the following type has been investigated: -dC/dt = K1 Cc (2) The techniques of both batch testing and continuous testing have been used to investigate this relationship. The technique of continuous testing, in which steady-state conditions are established, permits direct investigation of the above equation. In the case of batch testing, C is decreasing continuously

Jan 1, 1961

By Tim O’Neil

Question: Looking forward, do we face a future in which energy markets, energy policy and energy conflicts threaten to preoccupy, if not dominate, our concerns over economic growth, national security and domestic tranquility? The answer is, we may indeed face such a future. Question: What oil resource is comparable in size to the reserves of Saudi Arabia and presents a tremendous opportunity? The answer, the oil sands in Alberta, Canada. Question: What is the largest mineral staking rush in North American history, still under way? It has so far led to the development of two large mines. The answer is the Point Lake diamond strike in Canada’s Northwest Territories. It led to the development of the Ekati and Diavik mines.

Jan 1, 2004

RACAL COMMITTEE OF ARRANGEMENTS Henry McCormick, Chairman; David Watts, Secretary; H. H. Campbell, A S. McCreath, S H. Chauvenet, C. E. Stafford, George S. Comstock, Jones Wister, E. C. Felton, F. W. Wood, Harvey Fisher. CITIZENS' RECEPTION COMMITTEE Governor H. M. Hoyt, Hon John C. Herman, Hon Simon Cameron, Hon. J. D. Cameron, W T. Hildrup, Charles L. Bailey, W. W. Jennings, Lane S. Hart, H. U. Carter, Gilliard Dock, T. T Wierman, Jr, James Boyd, D. L. Jauss, Dr. T J. Dunott, S. C. Gilbert. William J Rose, James Lynah, Dr. H. B Buehler, William N Lamberton, John Wister, G. M. McCauley, David Fleming, John Q. Donney, M. E. Olmsted, H. S Gross, Henry Gilbert. John B. McPherson, Lyman D. Gilbert, F. W. Forman, L. S. Bent, A. J. Dull, F. R. Leib, Dr. G. W. Belly, James McCormick. The opening session of the meeting was held in the hall. of the Young Men's Christian Association, on Tuesday evening, October 25th. Mr. Jones Wister, of the Local Committee of Arrangements, introduced the Hon. John C. Herman, mayor, who, in a brief address, extended to the members present a welcome to the city, of Harrisburg ; Lieutenant Governor Stone made an address of welcome on behalf of Governor Hoyt and the Commonwealth of Pennsylvania. President Metcalf responded, on behalf of the Institute, to the cordial addresses of the mayor and lieutenant-governor. The following persons proposed for members and associates of the Institute, and recommended by the Council, were unanimously elected :* MEMBERS. William F. Aldrich, - Montevallo, Shelby Co., Ala. George H Blake, - Steelton, Dauphin Co., Pa. L. Bertram Cady, - Salisbury, N. C. John B. Church, - Pottsville, Pa. Walter S. Church, - Pottsville, Pa, Frank L Clark, - Pittsburgh, Pa. * In the following list are included those elected at a subsequent session of this meeting.

Jan 1, 1882

By Haigh J. E

An accurate measure of the earth's magnetic field can be made in a few seconds with the portable proton precession magnetometer. Such an instrument increases the applicability of the long successful method of magnetic prospecting for minerals. As an example of the usefulness of the proton magnetometer, a survey over volcanic rocks near Apsley (Tas.) was made.INTRODUCTIONA completely portable magnetometer whose operation is based on the free precession of polarized protons in the earth's magnetic field, is now available on the market at a price competitive with magnetometers based on the classical physical principles. The ease, accuracy, rapidity, and reliability with which measurements of the earth's total magnetic field can be made with the proton precession magnetometer, led to the try-out of the instrument in an actual field problem so as to evaluate fully the capabilities of the instrument. Such evaluation is important, because the history of magnetic prospecting has shown that whenever significantly improved instrumentation has been introduced, prospecting costs have been substantially cut and many areas in which the prospecting costs were formerly considered excessive in relation to probable returns, have become economic mineral prospects. The proton precession magnetometer offers the possibility of opening up new areas for successful magnetic prospecting.AN OUTLINE OF THE HISTORY OF MAGNETIC PROSPECTINGWhile an outline of the history of magnetic prospecting is not directly connected with the evaluation of a proton pre...

Jan 1, 1963

By C. Lemmer

The resolution with which the different categories of resources are forecast for Witwatersrand gold reefs should ideally tie in with block sizes that are optimal in terms of the variability structures of the reefs. A tool, called the ?variancegram?, is proposed as a basis for block size choice. A variancegram is intrinsic to the particular reef and mine concerned. A further requirement is the ability to attach global confidence limits to weighted average estimates built up from combinations of local kriged estimates. Approximations to derive global kriging variances based on variables derived from local kriging deliver hugely inflated results if ordinary kriging is used, and markedly better, but not accurate, values if simple kriging is used. These approximations improve as the number of samples used in kriging each block is increased. It is shown that the behaviour of the different components of the global kriging variance with increasing number of samples, all differs, but they all link to the variancegram for the particular reef. The variancegram can thus be used to correct the different components to the values they would have had if all samples were used in kriging each block, and so deliver the ?correct? global kriging variance, even though only a limited number of samples were used in kriging each block. The desirability of having very stable solutions implemented in production systems is taken into account in the proposals. It is anticipated that the same variancegram findings will also hold for other densely sampled deposits, but this remains to be investigated.

Jan 1, 2014

By Yves-Laurent Turcotte

Notre conférencier, Monsieur Yves L. Turcotte, Vice-président et Directeur général chez Promaintech Novaxa est diplômé en génie industriel de l?Université du Québec à Trois-Rivières et détient une maîtrise en gestion de projets de l?Université du Québec à Montréal. Il est une véritable sommité canadienne dans le domaine de l?amélioration de la performance des organisations. Provenant d'entreprises manufacturières et de services, il possède plus de 20 ans d?expérience en tant que développeur de technologies, conseiller et formateur auprès d?entreprises. Il a à son actif la réalisation de mandats dans plus de 400 entreprises. Il est reconnu pour sa grande capacité d?analyse et pour trouver des solutions novatrices et profitables aux problèmes des organisations les plus complexes. Aujourd'hui, il dirige Promaintech Novaxa, une division de DMR, qui a célébré son dixième anniversaire en 2006. Cette organisation ayant des places d?affaires dans la région de Montréal, Québec et Vancouver compte plus de 50 professionnels et a une carte de visite dans 16 pays. Les axes d?intervention sont le Management, la Productivité, la Fiabilité, l?Innovation et l?Amélioration Continue.

Feb 1, 2008

By F. Samimi Namin

During the process of developing surface or underground mines, some sites are considered for dumping of surface soils, while others are applied to reclaiming surface and waste disposal. For each kind of overburden, whether it be waste rock, low-grade material, or process tails, a separate storage site is considered so that it becomes possible to transport or recover the overburden separately. Decision-making must be completed by means of a selection process which takes into account the best methods of alternative sets in order to achieve these goals. This decision- making involves many parameters that are inter-related in that changes in some parameters affect the others. There are many methods of decision-making, however, Fuzzy Multi-attribute Decision-making (FMADM) and its functions are studied in this paper. The advantages of this method lies in its theoretical background, formulation, revising capability, unlimited alternatives, and consideration of the counteraction of the different parameters upon one another.

Jan 1, 2007

By T. D. Chatwin

While new jobs and taxes are major incentives for support of mining, stakeholders must also be assured that current jobs, resources and environment will be protected. Mining companies can help achieve stakeholder support by frankly addressing Acid Rock Drainage CARD) issues. To prevent ARD, miners must begin early in the mine life-cycle to develop an ARD management plan and integrate it into the mining operation. As this proactive preventative program is initiated, mining companies also need to engage and collaborate with stakeholders to insure that their expectations and needs are met. Stakeholder engagement is enhanced as mining companies emphasizes the value of clean and available water for current and future generations.

Jan 1, 2011

By David A. Summers

Coal is increasingly viewed as one of the major fuel resources of this country for the remainder of this century. The need to extract a greater percentage of the coal in a given seam, together with advantages of improved safety, indicates that longwall mining will become more widely used within this time frame. A novel method of mining coal on a longwall face, utilizing high pressure water jets, is herein described. The mining machine proposed will exploit the stress conditions which exist on a longwall panel in order to achieve the required productivity while at the same time reducing respirable dust and methane ignition hazards. The water jets will excavate only the boundary of the extracted seam section, and thus the energy requirement of the machine will be minimized. The action of the machine is similar to that of an existing coal plow, except in that the wedge teeth of the plow are replaced by oscillating high pressure water jets. The machine can, therefore, cut to the depth and at the speed of existing shearer units at equivalent power levels. The removal of impact stresses from the machine will reduce downtime required for maintenance and replacement of picks and lower the load on the haulage motor of the system. The ability of the machine to increase the depth of cut without an increase in horsepower will further improve productivity when transportation systems to remove the greater production are in operation.

Jan 1, 1974

By Thorndycraftm R. B.

"PURPOSEThe purpose of this presentation to the Canadian Mineral Processors is to review gold heap leaching systems currently in use and discuss their applicability to Canadian ores. The author's experience with the development and operation of heap leaching spans the past four years at. Pinson, and visits to many ether heap leaches in the western United States.INTRODUCTIONBy way of introduction to the heap leaching system, I will describe in slight detail the method used at Pinson Mining in northern Nevada. This will be followed by a discussion of optional methods in use at other operations visited.The Pinson orebody is a finely disseminated, well-oxidized hydrothermal deposit. Gold particles are finer than 20- microns. The orezone hostrocks are metamorphosed and silici¬fied limestone and shale. Sulfides and carbonaceous materials are negligible.The Pinson open-pit mine has operated since June 1980. It produces 1500 tpd of C.I.P. mill feed averaging .10 oz gold per ton, and 1500 tpd of heap leach material averaging .025 oz gold per ton. Cutoff grades are 0.04 for mill feed, and 0.01 for heap leaching. Stripping ratio is 9 tons of waste and leach grade to 1 ton of mill feed.The project is located in northern Nevada at 4900 feet above sea level.,Winters are fairly severe, with freezing conditions affecting operations from early December through April. Although officially designated as ""high-mountain desert"" country, snow and/or freezing rain occur almost every week of the winter.To date, all Pinson production-scale heap leaching has treated run-90,000 tons of ore are stacked on 300 foot square clay leach pads. Cyanide leach solution is applied through ""wobbler"" sprinklers at .0025 gpm/sq ft for 60 to 90 days. The pregnant solution flows from the heap by gravity to plastic-lined ditches, into a collection sump and then through buried piping to the 2.2 million gallon pregnant solution pond."

Jan 1, 1984