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Although grinding mill liner life has been the subject of extensive studies, evaluation of the effect of liner design on power consumption, a far more significant part of total grinding costs, has been less comprehensive. The factors that effect ball mill energy efficiency are reviewed, and attention is then focused on the mechanisms of grinding. The trajectory of the outer row of balls, with different lifting face angles, is derived, and basic recommendations for mill speed and liner configuration are presented.

Jan 1, 1981

By B. M. Davis

The problem of assessing uncertainty in grade estimates has been a topic of research and debate since kriging was first introduced. Use of the kriging variance was originally touted as all that was necessary in order to produce confidence limits for grade estimates. Since then the prudence of using the kriging variance for confidence interval estimation has been questioned, and techniques such as the jackknife and conditional simulation have been proposed to develop "true" interval estimates. This paper compares the differences between interval estimates produced by the three methods and makes conclusions about the performance of confidence intervals produced by the different methods.

Jan 1, 1997

By B. S. Graves

Deep well disposal of selected industrial wastes has been proved feasible and acceptable in the New Orleans area by several industries including Shell Oil Company's Norco Refinery and Chemical Plant where three of the six successful disposal wells in this area are operating. Well design and procedures for restoration of capacity are based, in most cases, on the principles of brine injection developed by oil producers in South Louisiana. Geological formations in the Gulf Coast area are suited to this type of injection because receiving strata are porous, isolated from sources of potable water and their water is compatible with the liquid wastes to be injected. This method of disposal is a simple, complete and economical solution to the problems presented by certain hard to treat wastes.

Jan 1, 1964

By VÍCTOR VÁZQUEZ-VÁZQUEZ, GUILLERMO TIBURCIO-MUNIVE, María M. Salazar-Campoy, JESÚS L. VALENZUELA-GARCÍA, OFELIA HERNÁNDEZ-NEGRETE

The present study examined a process for precious metal recovery (silver and gold) from difficult minerals which exhibit refractory characteristics to cyanidation and ammonium thiosulfate leaching (low extraction and high consumption of leaching agent). It is well known that mangano-argentiferous minerals are mainly composed of manganese, silver, gold, and iron. In this research, a mineral sample from Monte del Favor mine, located in Hostotipaquillo, Jalisco, Mexico, was physically and chemically characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), fire assay, and atomic absorption spectroscopy (AAS). Two-stage leaching was carried out: first to eliminate manganese from the sample using sodium sulfite (Na2SO3) as a reductive reagent and sulfuric acid (H2SO4) and a second stage to dissolve silver and gold with sodium hypochlorite (NaClO) and hydrochloric acid (HCl); the results show extraction around 96% for Mn and 98.73% and 83%of Ag and Au, respectively. The usefulness of high acidity and Na2SO3 to obtain good results in Mn and Ag leaching is discussed along with the roles that HCl and NaClO play in the dissolution of Ag and Au values.

Apr 15, 2020

By Gordon B. French

The Occidental Oil Shale mining and retorting system for the production of shale oil has many advantages over the conventional underground mine and surface retort systems. For example only a portion of the oil shale is mined and transported to the outside, where it blends with the existing shale talus found on most of the slopes in the immediate area. The retorted spent shale is retained underground so that it does not become a surface disposal problem. The process consumes only minor amounts of water which is produced in adequate amounts in the retorting to fulfill all mining operations needs without outside supplies. Noise and dust levels are kept to a minimum with most of the facilities located underground. The exception being the generating stations and facilities as required to monitor air and water qualities, and last but not least, more than four times as much oil is pro¬duced from a given acre than from conventional surface processing. With the increased thicknesses as available on the government monopoly area this number could be increased by a substantial amount.

Jan 1, 1975

By Stuart F. McTavish

Mechanically suitable grinding mills became available to the mining industry in 1908. Since then, mill operators have been searching for the best material and design with which to line the mills. These liner systems had to fulfill several criteria. Most important, they had to last long enough in an operating mill to protect its structure from the abrasive wear of the ore and the grinding media. In addition, they had to be capable of efficiently transferring the energy from the mill to the mill charge in order to facilitate the grinding process. And these liners had to be easy to install and remove. The first liners used were generally made of cast white iron, Hadfield manganese, unalloyed high-carbon steel and composites of steel and concrete or cemented in flint blocks or natural stone. In the early 1920s, pieces of solid rubber truck tires were used as emergency repairs for broken cast metal liners. Thus was rubber first introduced as a mill liner material. The first patent for rubber mill liners was awarded in 1921 to James Denny and Rolla Watson, both of the Coniagas Mine in Cobalt, Ontario, and to Dale Barnum of the Comstock Lode in Virginia City, NV. This original design was covered under US Patent No. 1470597. It had a fabric backed rubber that was bonded to the shell of the mill.

Jan 1, 1990

By Henrique D. G. Turrer, Robert F. Winterfield, Jobe E. Wheeler, Marcello R. Cru, Baojie Zhang, Pedro P. Pinto

Efficient particle classification is essential to enhance gravity and magnetic separation stages in one iron ore beneficiation plant. This study investigates the use of high-frequency screens to process finely ground iron ore, focusing on two size cuts: 400 μm and 100 μm. Pilot-scale trials were performed on four ore blends using a full-scale screening unit. A total of 48 tests were conducted, evaluating the effects of panel aperture, solids concentration, wash water, and feed particle size distribution. Results showed that wash water improved efficiency by up to 5%, while a solids concentration near 40% w/w delivered high separation performance with minimal ultra-fines in oversize streams. Apertures slightly larger than the target cut sizes yielded better precision in particle separation. Feed particle size distribution had limited impact on efficiency. The investigation successfully identified optimal screening conditions, including aperture selection, to achieve the most effective separation performance for downstream concentration processes.

Feb 22, 2026

By Yifan Ding, Shemek Oginski, Patrick Finn

The Manhattan section of the New York Water Tunnel No. 3 constructed by the Schiavone/Shea/Frontier-Kemper Joint Venture is a $668 million project. The contract includes a tunnel drive of 8.85 km (29,045 feet), tunnel lining of 14.77 km (48,468 feet)and construction of nine shafts ranging in depth from 143 m (469 feet) to 169 m(555 feet). Construction methods for excavation of the shafts are presented including raise bore, ground freezing, soil excavation, blasting, slashing, muck handling, rock support and shaft final concrete lining.

Jan 1, 2007

By J. Kulas, J. Weaver, K. Hagley

An assessment of potential groundwater movement beneath the tailing impoundment at the Red Dog Mine was performed, and has indicated a unique aquifer situation within sub-permafrost groundwater at the site. The aquifer was shown to be isolated from both vertical recharge and a real discharge, and is characterized as a virtually no-flow system. The permafrost resulted in a deep aquifer with high tidal efficiency, meaning that variable surface loads are easily transmitted to the fluid. The tidal efficiency has been characterized through analysis of water level fluctuations that respond to earth tides, barometric pressure loads, and loading from the pond.

Jan 1, 2002

By Rafael C. Castro, Geoffrey Hughes, Fredrick (Rick) Vincent, Philip H. Albert

Seven pairs of drop and ventilation shafts, between two and nine feet in diameter, will convey combined sewer flow to a 230-foot-deep, 26-foot diameter storage tunnel. This paper will present case histories for each site. Discussion will include functional requirements, program and site access constraints, structural design, geology, the variety of excavation and lining construction methods used, and lessons learned. Noteworthy observations include the importance of assuring competent ground sup-port at the soil-bedrock interface and of achieving tight verticality tolerance using both top-down and raise bore excavation methods.

Jan 1, 2007

By T. W. White

One of the objectives of today's mine superintendent is to increase his equipment availability. To this end we have seen improved scheduling procedures, preventive maintenance programs and extensive drive training and operating procedures. However, until recently, one area that has changed little in the past twenty years is the method of refueling and servicing mine equipment. In looking at mines across the country continually one encounters the hazardous oil soaked ground, the hand held fuel nozzle and the maze of hoses of the "traditional" fuel stop. By adapting technology developed in the construction and aircraft industry, current fueling and servicing practices can be easily improved. The result will be less nonproductive time, less downtime from engine failures and increased security from major refueling fires. The time saved almost amounts to having another truck in the fleet! One feature of the improved servicing practice is the implementation of high flow fueling. For trucks now on the market, a flow rate between 120 and 150 gam is feasible, about 90 gam greater than current practice. This flow rate could be increased even further as larger trucks come into use. A second idea borrowed from the aircraft industry is the use of positive lock type connection nozzles that automatically shut off when flow stops. These may be used for fuel, water, oil and hydraulic systems to eliminate spillage and assure that clean fuel, oils, and water are delivered to the vehicles. The reduction of fuel spillage lessens the threat of major fires resulting: in equipment damage and loss. Eliminating fire hazards will become even more important as the turbine engine with its lighter, more volatile fuels come into common use.

Jan 1, 1972

By Paul Soros

There has been a steady increase in shiploading capacities in the last 20 years. One of the reasons has been the general increase in ship sizes, with the largest vessels currently around 280,000 DWT in the bulk trades. Obviously, the large vessels can accept loads faster and their economic utilization justifies higher loading rates, up to a point. The high capacity facilities have loading rates far beyond this point. The economic logic of these facilities is based on the fact that for a given annual throughput the capital and operating cost of a single high capacity system is less than that of two smaller systems. Thus, where the projected throughputs are large, there is a great incentive to reduce capital costs by maximizing capacity. Tubarao, in Brazil, designed for a 100 million ton per year throughput with one finger pier and one high capacity berth is a successful demonstration of this approach. In the current state of the art, the high capacity systems have shiploading capacities in the range of 10,000 - 16,000 TPH, for annual throughputs of 20 million tons and larger per loading berth.

Jan 1, 1982

By John W. White

Anthracite mine refuse, or culm dump material as it is sometimes called, is the waste material resulting from the sizing and cleaning of run-of-mine deep and strip-mined anthracite coal. It may also contain mine rock, carbonaceous shale, pyrite, and other debris from mining operations. This material is generally stored in piles or banks, some of which are over 100 years old. Many of the older banks contain a considerable amount of good coal, particularly in the finer size ranges, since these sizes did not have any particular economic value in the early days of anthracite mining. Today, the refuse material from a cleaning operation must be piled in an orderly fashion and in such a way as to minimize the tendency to ignite. There are well over 400 of these banks in the anthracite region containing over 1100 million tons of refuse located in the north-eastern part of Pennsylvania. The banks range in size from a few thousand tons of material up to as much as 13 million tons. Most of

Jan 1, 1972

By Jr. Chesson

"Phosphate" is a misnomer as often used. The word is increasingly used to refer to any material containing phosphorus - an element essential to any form of life. Phosphate rock, a mineral - fluorapitate - is recovered from Florida's sedimentary deposits in particle sires ranging from 0.1 to 13.0 millimeter. This product of mining, washing, screening, and flotation is commonly called "phosphate". Its phosphorus content, measured and reported as P2O5, varies from 29% to 35%, and is essentially insoluble. "Phosphate" is also used to describe products containing soluble phosphorus obtained from acidulation of phosphate rock with mineral acids; primarily, sulfuric acid. Many miners have nearby chemical plants wherein phosphate rock is converted into upgraded products such as phosphoric acid, superphosohates, and ammonium phosphates with 45% to 70% P205, soluble and suitable for use as fertilizer. The rock and upgraded products are all commonly called "phosphate"; the plants, "phosphate plants' and the producers collectively are known as the "phosphate industry". The public in Central Florida generally loses identification of the individual operators that include major corporations such as IMC. Williams Companies, W.R. Grace, Mobil, Embark, U.S. Steel, Borden, American Cyanamid and others. They all become just a "phosphate company".

Jan 1, 1978

By Ernest M. Spokes

Maximum fan efficiency can only be obtained when the fan has the correct combination of size, speed, and blade setting to provide the required flow of air against the mine resistance. As the mine grows older, resistance decreases unless old workings flow is restricted, and new combinations of speed and blade setting or different fan sizes may provide greater economy.

Jan 1, 1977

By C. G. Clifton

The Oatman District produced approximately 2.2 x 10 6 ounces of gold and 0.8 x 10 ounces of silver between 1897 and 1942. A total of 3.8 x 10 tons of ore averaging 0.58 O/T gold and 0.17 O/T silver was extracted from eight major orebodies and a number of lesser deposits. Oatman lies at the center of a trachyte-latite-rhyolite volcanic complex which contains at least one resurgent caldera. The orebodies are typical epithermal quartz-calcite + adularia lode deposits which are very deficient in sulfur. Ore deposition has occurred within dilatant zones on faults which radiate from a common point within-the complex. Fischer-Watt Mining approached the Oatman District with an integrated exploration program utilizing four basic procedures to define the characteristics of past productive areas the results of which were applied to unexplored portions of the vein system. These procedures, listed in their order of usefulness, in defining known and prospective mineralized zones are: vein contouring, detailed alteration mapping, fluid inclusion temperature determinations, and geochemical sampling.

Jan 1, 1980

By N. A. Abdel-Khalek

An experimental study was carried out to compare the results of laboratory column flotation versus conventional flotation for the cleaning of fine coals of different rank and their oxidized samples as well as discrete size fractions. Surface oxidation caused a significant reduction in the flotation yields achieved with both methods. However, the column flotation produced concentrates? of lower ash content. The recovery -size curve achieved with column was similar in shape to that obtained with conventional cell, with superior results in the region of fine fractions. The influence of some column operating parameters was also discussed.

Jan 1, 1990

By I. Demers

Doyon mine, Quebec, Canada evaluates the possibility of desulphurizing their tailings to produce material to be used in as cover over the acid generating tailings disposal site. Laboratory tests were conducted and showed that a single-layer cover made of desulphurized tailings placed over reactive tailings can prevent the generation of acid mine drainage. Modelling with the software Vadose/W was undertaken to optimize the design parameters, namely cover thickness, water table position, and residual sulphide content of desulphurized tailings following laboratory work. It was found that the optimal configuration includes a 1 m desulphurized tailings cover containing 0.8%S, with the water table kept at the interface between the reactive tailings and the cover. To maintain the cover performance to reduce oxygen flux towards acid-generating tailings even in the event of a long dry period, a sand layer is suggested to protect the cover from excessive evaporation. It is possible to reach the environmental objective chosen for Doyon mine (10 mol/m2/year) with the protective sand layer, even in extremely dry conditions.

Jan 1, 2008

By J. L. Coburn

The Huari-Huari ore body is located in Southern Bolivia, at an elevation of approximately 3,800 meters above sea level. The ore is a complex massive sulfide, slightly marmatitic sphalerite, in a fault fissure filled hypo- thermal vein in Paleozoic shales and quartzite-altered sandstone. The sphalerite has common associations with pyrite and quartz and is frequently intricately intergrown with stannite, chalcopyrite, and pyrrhotite. The sphalerite also contains numerous inclusions of pyrite, marcasite, galena, boulangerite, jamesonite, quartz, arsenopyrite, and cassiterite. A research program was undertaken to develop a flowsheet for the recovery of separate silver, zinc, and tin concentrates by selective flotation. Based on this experimental work and subsequent flowsheet development, engineering and construction of a 500 metric ton per day concentrator was undertaken. This paper describes the process that was developed for the Huari-Huari ore and the unique aspects of the Huari-Huari concentrator.

Jan 1, 1977

By H. Vigil Fernandez, G. Peach

The Musaimeer pump station and outfall project located in Doha Qatar, was designed to collect and manage ground and stormwater and then discharge the treated waters offshore. The project constructed a long outfall tunnel using an EPB TBM with segmental lining, each tunnel ring being 1.35 m in length with an internal diameter of 3.7 m.. The diffuser structure was a 6-arm structure, measuring 294m by 40 m connected to a central manifold in turn connected to the TBM constructed tunnel via a riser shaft drilled from an off-shore barge. This technical paper will discuss the planning, methodology and construction practices employed to connect the TBM tunnel to the diffuser structure 10.2 km offshore.

Jun 13, 2023