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By N. Shi, T. G. Joseph

The design of dippers for cable shovels has essentially remained unchanged for the last 100 years. In the past 10 years, shovel manufacturers have started taking another look at dipper design, resulting in changes that have borne models from major manufacturers that address some of the wear conditions and material retention problems that dominate maintenance and operational costs. However, with the exception of added lateral curvatures to the front and corners of the dipper, the geometry is essentially unchanged. This paper looks at the criteria that have resulted in the first new cutting dipper design in a century. The design is based on kinematic considerations, reflected in a revolutionary geometry that matches the range of motions of the shovel, designed to minimize wear, impact loading and power required to dig, thus maximizing productivity for a minimum energy requirement. The shape configuration is such that the weight of the dipper is reduced through wall thickness, enabling a larger capacity dipper to be conceived for the same shovel. Benefits are reflected in reduced operational and maintenance costs and increased productivity.

Jan 1, 2006

By H. Foster Bain

I. INTRODUCTION. By H. FOSTER BAIN.+ THE recently aroused public interest in the conservation of our natural resources has peculiar importance to mining-men, since they deal with resources which are stored products. Within certain limits, the fertility of a worn-out soil may be restored, deforested areas can be replanted, one year's wasted water-supply is followed by another; but coal and ores, once taken out, cannot be mined again, and should therefore be conserved with especial care. This means, however, not that mining should be restricted, but that it should be done most economically and with the minimum of waste.

Nov 1, 1908

By Krishna Parameswaran

This paper illustrates sustainability considerations in copper hydrometallurgy using examples of practices at ASARCO LLC, an integrated U.S. primary copper producer. Using the classic Brundtland Commission development of sustainable development, i.e., “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper discusses how copper hydrometallurgical processes can be sustainable. The examples used to illustrate sustainable development and related concepts include: water conservation opportunities in milling and leaching operations; implementing green chemistry and promoting product stewardship in the electrorefining of copper.

By Mike Samuels, John Starkey

"This paper examines test results and grinding mill design for the recent Fortune Minerals’ NICO Project, located in the Northwest Territories. SAG milling and rod milling options are compared. Rod milling is clearly shown to be the best option because of the ore’s extreme resistance to breakage in a SAG mill environment.Surprisingly, the Bond Ball Mill Wi was 13 kWh/t for this ore. The Bond Rod Mill Wi was 20 kWh/t, whereas the SAG pinion energy to grind the ore to T80 1.7 mm was 30 kWh/t. The existence of ore with this ratio of SAG hardness to Bond BM Wi has not been previously observed. If not considered, this critical relationship may adversely impact the accuracy of mill design. This paper substantiates the significance of these findings to achieve successful grinding design on ore that is macro-competent during primary size reduction, but relatively normal during secondary grinding.INTRODUCTIONThe NICO Cobalt-Gold-Bismuth-Copper deposit is located 160 km northwest of the City of Yellowknife, Northwest Territories. It is the largest IOCG-type deposit (aka Olympic Dam-type) currently recognized in Canada with Mineral Reserves of 21.8 million tonnes contained within a larger 57 million tonne, lower-grade Mineral Resource. The project, owned 100% by Fortune Minerals Limited, has been assessed in a positive definitive feasibility study, subject to underground test mining and pilot plant testing, and is now in the permitting stage to develop a combined open pit and underground mine and process plant. An updated process flow sheet incorporates conventional crushing, grinding and bulk flotation, followed by filtration for shipment of a concentrate to a purpose-built refinery proposed to be built near Saskatoon, Saskatchewan. At the refinery, separate bismuth and cobalt concentrates will be produced following regrinding. The hydrometallurgical process methods include: pressure acid leach, precipitation, ion exchange, and electro-winning for recovery of cobalt as 99.8% cathode; solvent extraction and electro-winning of by-product copper cathode; ferric chloride leach and electro-winning for recovery of bismuth as 99.5% cathode; and cyanidation of the leach residues for recovery of gold as doré."

Jan 1, 2010

By M. J. Nicol

The kinetics of the dissolution of colloidal silver in aerated cyanide solutions has been investigated with the aim of developing a relatively rapid and convenient method for monitoring the ?leaching power? of solutions typically used in the cyanidation process. Experimental results obtained are consistent with an electro-chemical model, in which the mixed potential is set up in the active region of the polarization curve for the anodic dissolution of silver, giving rise to a rate of dissolution which is controlled by the rate of mass transport of either cyanide or oxygen to the surface of the silver. The rate of dissolution of colloidal silver was found to respond to variations in the reactant concentrations in a similar manner to gold (and silver) in a typical free-milling ore. The use of this technique for the monitoring and control of the cyanide leach process is discussed.

Jan 1, 1998

By T. Szendrei, S. Tose

The generally accepted view in rock blasting is that the sources of energy for the fracture and movement of rock reside in the shock wave and gas action resulting from the explosion, and yet the mechanisms by which these sources interact with the rock have remained unclarified. It has also been noted that up to 50% of the work capacity of an explosive released in a blast cannot be accounted for by field measurements of energy partitioning. In this study, we describe a physical model that details the response of rock to both shock wave and gas action. An analytical model based on momentum conservation is derived to describe the dynamics of shock-driven expansion of the blasthole. Radial expansion of the hole is the key parameter that permits the derivation of the following characteristics of rock response to shock loads: hole expansion time; volume of displaced rock; energy consumed per unit volume; expansion energy efficiency; stress wave pulse length; gas pressure in enlarged hole. Soon after the completion of hole expansion, the shock wave degenerates to an elastic stress wave that runs through the burden. Blasthole expansions of between 50% and 300% of diameter are completed in under 1 ms and, depending on rock properties, consume 32% to 42% of the detonation energy or about 55% of the available mechanical (Gurney) energy. Gas pressure in the enlarged holes in five rock types is between 35 MPa and 650 MPa, and drives the mass movement of burden rock.

Oct 9, 2024

By C. W. Reno

"THE LORNEX MINING PROJECT is one of several large-tonnage, low-grade operations recently placed in operation in British Columbia. It is located in the Highland Valley in the south central portion of the province. This area is described as a divide valley at an elevation range of 4,000 to 6,000 feet and is situated on the divide between two drainage systems. The major drainage to the west flows into the Thompson River and to the east and south the drainage enters the Nicola River system. This open-ended valley lies between low, rounded mountains in fairly heavily-wooded country. Prior to the commencement of copper mining activities, the first by Bethlehem Copper Corporation Ltd. over ten years ago, the valley was only sparsely settled. A few small ranches were in existence on the several Indian Reserves located along the valley bottomland. There has also been a small amount of logging activity in the valley, although much of the area is covered by dense lodgepole pine which has little or no value to the loggers. As the mining interest mounted with further discoveries of the disseminated copper ore typical of the district, much of the valley was covered with mineral claims and exploration drilling was carried on by several companies at various times. At the time Lornex was preparing to commence major construction work in early 1970, there was very little activity of any kind in the Highland Valley outside of the Bethlehem operation and a small amount of ranching."

Jan 1, 1973

By Walter Hermülheim, Klaus-Dieter Beck

In German hardcoal mining approximately 1 or 2 cases of spontaneous combustion are recorded per 10 million tonnes of saleable output. In approximately every 20th spontaneous combustion case, CH, is ignited. By the example of a fire caused by spontaneous combustion on Friedrich Heinrich colliery, an overview on the measures taken for firefighting and explosion prevention is given. These measures comprise (in sequential order) - early fire detection by CO-monitoring, - gob-sealing measures against ventilation air leaks, - full-space inertization of the coalface subsequent to a CH,- deflagration, - installation of a target inertization of the caved-in gob under the protection of the full-space inertization, - re-opening of the fire zone and reestablishment of the ventilation-air current, - completion of the salvaging work with continued target inertization of the caved-in gob and further sealing measures (monolithic packing), - sealing of the coalface after salvaging. The measures described allowed gain of control of a safety- critical (because close to the face) gob fire caused by spontaneous combustion, in spite of a CH, deflagration, within few days only, and salvaging of equipment from that coalface and start-up of the follow-up coal-face on schedule. The measures taken as well as the experiences gained allow deduction of general safety criteria for fighiing of gobfires caused by spontaneous combustion, and for controlling the explosion risk. e.g. - warning and alert thresholds for early detection of fires, - criteria for spotting of the zone of fire, - rules for tightening caved-in gobs, - thresholds for the retreat of firefighting crews from the vicinity of the zone of fire, and for starting ineiization, - considerations for positioning of and strength requirements for stoppings with/without inertization, - flow-by-volume adjustment of inertization, - safety rules for work with respiratory apparatus in the inertized zone, - safety rules for the re-opening of zones of fire. The considerations end up in the conclusions that the duration in terms of months of the classic cycles of sealing, waiting, and reopening can nowadays be reduced to a few days only by purposeful combination of full-space inertization and locally confined tar- get inertization of the gob area. The earlier high risks incured by the mine resuce squads en- trusted with sealing of zones of mine fires under explosion hazards can be reduced by the method described, provided the safety regulations are conformed with. In this way, intertizing contributes substantially to reduction of down-time caused by mine fires, to preservation of recoverable parts of the deposit, and to improved safety of the fire-fighting crews.

Jan 1, 1997

By C. W. Owings

Recent recommendations of the Bureau of Mines regarding, rock dusting to prevent dust explosions in coal mines have been issued as Mine Safety Board Decision 32 and printed as Information Circular 7109.5/ The last paragraph on page 2 of I. C. 7109 states: After a mine or any part of a mine has been rock-dusted, samples of dust for analysis should be taken from the floor, ribs, roof, and timbers at such intervals of time as will give apple warning of need far redusting in order to maintain the required minimum percentage of incombustible in the mine dust. Details of the methods of sampling and analysis are given in Bureau of Mines Information Circular 7113.

Jan 1, 1940

By Yu Zhenquan

At the construction site of Bao Shan Iron &. Steel Mill in Shanghai, lots of RC driven piles with length of 50 to 60m were applied. The most unfavourable distribution of stress along the pile shaft was known by measuring the compressive and tensive stresses. With analysing the test results a phenomenon of impact fatigue of RC pile was discovered, the range of impact fatigue and its critical zone can be distinguished. Finally some countermeasures are presented to avoid the impact fatigue of RC long pile.

Jan 1, 1991

By Ad. Breyre

For more than 20 years, Belgium, leading all the coal-mining countries, has made increasing use of sheathed explosives, which wore first suggested by the late E. Lemaire, predecessor of the author gas Director of the Institut National des Mines. It appears to the author that it will be valuable to show how the use of sheathed explosives has developed in Belgium, how the various difficulties encountered in their manufacture have been overcome gradually, and the tyros of sheathing that have survived and the reasons for their survival.

Jan 1, 1940

New Zealand depends on foreign investment for economic development. This also applies to the development of New Zealand's mineral resources. For this foreign investment to happen there must be some incentives to attract the investment. While prospectivity is the dominant parameter considered by investors it is not a variable that can be changed, only the perception of New Zealand's prospectivity. Other parameters likely to be considered are sovereign risk, red tape, green tape, land access, civil unrest, land claims, social risk, labour relations, infrastructure and natural disasters. Regulators and political will can vary some of these parameters. Where New Zealand fits internationally can be measured by investors' perceptions of these parameters. Following on from these perceptions New Zealand can be seen to have advantages in some areas and be disadvantaged in others. How to deal with the disadvantages to give investors confidence is not easy in the New Zealand environment where the development of mineral resources plays a small part in an economy dominated by agriculture. Added to this is the current global state of the minerals industry which offers even more of a challenge to attract foreign investment to develop New Zealand's mineral resources.

Jan 1, 2000

By John G. Groppo, James C. Hower, Cortland F. Eble, Rick Q. Honaker, Alireza Valian, Stephen F. Greb

Coal and coal combustion byproducts are potential candidates for alternative resources of REEs (rare earth elements). The Illinois Basin is a major coal-producing district in the USA, but little work is available on speciation of REEs in the basin’s coals. In this study, a total number of 382 samples from known locations in the Illinois Basin coal beds were acquired, analyzed for their REE contents, and investigated for any spatial trends or chemical correlations. This study includes Springfield, Herrin, and Baker coal beds—the most heavily mined coals in the basin. An average coal ash from the basin contains 320 ppm REE, with Baker being the highest (407 ppm on average). However, the distribution of REEs in the coal beds was laterally and vertically heterogeneous. A number of trends were found in the REE variations. The most important trend was the relationships of the REE concentrations and fractionations with the distance from the syndepositional sandstones. The total REE concentrations were higher in the proximity of the sandstones, likely due to the increased deposition of detrital material. This increase was the most significant in Springfield coal (90%) and least in Baker (6%). Those coal samples from the Springfield and Herrin coal beds distal from the syndepositional sandstones had a heavy to light REE ratio (H/L ratio) of 0.40 on average, whereas in proximal locations, the ratio was dropped to an average of 0.30. This trend was not significant in the Baker coal bed. In general, higher mineral matter in the coals was associated with higher REEs. In coal preparation plants, refuse rocks can have up to 360 ppmREE. However, the ashes of the cleanest coals had higher REE levels. Such ashes also have a higher ratio of heavy to light REEs. The highest REE concentrations were found in the claystones and the shales associated with the coal beds. Since the naturally occurring calcite, quartz, and pyrite samples were depleted in REEs, an association of REEs with the clay minerals can be suggested.

Jul 20, 2020

By Mark Aylmore, Guy Deschenes

"Increasing pressure are motivating the gold mining industry to develop a substitute to cyanide for leaching gold. This effort in mainly based on the high toxicity of cyanide and on the lack of efficiency of cyanide in the treatment of mildly refractory gold ores (sulfides and pre-robbing). Consequently, in only a few years, consortia have been created to elucidate and implement a new technology. The most promising lixiviant that has been selected to replace cyanide is thiosulfate. This paper will present a critical analysis on the latest developments in thiosulfate leaching and illustrate the potential and limitations of the technology with experimental data. Finally an assessment of the cost and performance of thiosulfate leaching relative cyanidation will be evaluated.INTRODUCTIONConcerns regarding the toxicity of cyanide and inability of cyanide solution to effectively leach some carbonaceous gold ore or mild refractory gold ores have made the gold mining industry evaluate alternative lixiviants to leach gold. This concern has been heightened recently by the cyanide spill at a mine in Romania, which devastated a 250-mile stretch of the Danube River and its tributaries, and the environmental damage at Ok Tedi mine in Papua New Guinea. Some countries and locations have prohibited the application of cyanidation to recover gold, such as, California and Colorado States, Japan and Turkey etc.There are several potential non-cyanide lixiviants (Sparrow and Woodcock, 1995) for gold extraction, such as thiosulfate, thiourea and halogen. A pilot feasibility test (Marchant and Broughton, 1987) had suggested that thioureation might result in acutely toxic byproducts even after treatment. Scientists of Swedish Academic of Sciences reported that thiourea is a carcinogen. Halogen is also a pollutant to the environment. Thiosulfate leaching appears to have very good potential as an effective and less hazardous procedure for gold and silver extraction from auriferous ores. In addition to being much less toxic and relatively cheap, it forms a stable anionic complex with gold but is less reactive to other metals, for instances, copper and carbonaceous materials, in comparison with cyanide."

Jan 1, 2001

By James A. Schneider

Selection of resistance factors within Load and Resistance Factor Design (LRFD) requires accurate assessment of uncertainty and bias in load and resistance. To date, many studies have focused predominantly on the assessment of uncertainty, while the potential for bias appears to be the dominant factor in design for consistent levels of reliability under a variety of situations. Bias comes from factors which have been ignored in design method development but significantly influence resistance when extrapolating from conditions typical of databases to those at a given site. Uncertainty and bias can be quantified as the coefficient of variation and mean (or median) of a data set, respectively, for statistical assessment of load and resistance factors. This paper first presents an overview of statistical assessment of resistance factors, and then discusses factors that influence uncertainty and bias when extrapolating to situations outside of conventional databases of driven pile axial capacity.

Jan 1, 2009

By A B. Christie

Known epithermal deposits in the Coromandel region belong to the low-sulphidation type, represented by three subtypes: (1) andesite-hosted epithermal Au-Ag, (2) rhyolite-hosted epithermal Au-Ag, and (3) andesite-hosted polymetallic veins. Paleo-depths for a range ofdeposits are estimated using various features including: paleo-surface indicators (e.g. sinters), hydrostatic pressures estimated from homogenisation temperature measurements on fluid inclusions, and alteration mineralogy. Paleo-depth estimates to the base of the ore zone for the rhyolite-hosted Coromandel deposits are in the range 200 to 500 m. Andesite-hosted Au-Ag deposits have more variable paleo-depths, and are deeper (up to 950 m) in those deposits with base metals at depth. The majority of Coromandel Au-Ag deposits have limited depth extents (<200 m) of economic grade mineralisation, although Waihi and Karangahake are notable exceptions with depth extents of 575 m and 700 m respectively. Limited depth extents of economic ore are a feature of epithermal systems worldwide and are commonly attributed to gold deposition from boiling fluids. Under hydrostatic conditions in epithermal/geothermal systems, boiling in an up-flowing hydrothermal fluid is controlled by the boiling point for depth (BPD) curve. From fluid inclusion studies of many low-sulphidation epithermal systems, deposition of electrum in economic concentrations appears to be confined to a temperature window of 260 to 180¦C. This means that for dilute, gas-poor fluids that follow the BPD curve, gold deposition is limited to a vertical depth zone of about 400 m, with its upper boundary at about 100 m below the ground surface. The greater depth extent at Waihi and Karangahake, can be explained by mixing of/a deep, hot (300¦C) fluid with cooler (c. 200¦C) heated ground waters. This has the effect of lowering the 260¦C isotherm by up to 300 m, thereby increasing the depth range of economic grade gold deposition within the 260 to 180¦Cwindow of electrum deposition.

Jan 1, 2000

De Beers? Finsch diamond mine began operation in the 1960s as a surface project using the latest technology available. During the 1990s, the operation, located about 160 km (100 miles) west of Kimberley, South Africa, began its move as an underground mine. The earlier stages (Blocks 1, 2 and 3) of underground work at Finsch used open stope mining methods, also using the latest in technology. The mine began developing Block 4 in 2004. How-ever, studies on this level showed that block caving was a more efficient mining method than open stoping. It was during those studies that De Beers determined that Block 4 would be a good candidate for testing Sandvik?s automated truck haulage technology.

Jan 1, 2008

Exploration work at the southern flank of the Mt. Coffin diapir has encountered three different types of copper ores: copper carbonate, largely malachite; secondary sulphides, mainly chalcocite replacing pyrite; and a primary arsenopyrite-tennantite-tetrahedrite-chalcopyrite association. The secondary copper ore is occasionally stratiform but mainly erratic at the contact between tillites and siltstones of the Tapley Hill formation.There have been two stages of primary mineralization.1. Arsenopyrite, tennantite, and tetrahedrite occur in siderite veins.2. Revival of the diapirism has caused fracturing and local brecciation of the rimrock and subsequently ascending solutions precipitated chalcopyrite. The chalcopyrite also partly replaced arsenopyrite, tennantite, and tetrahedrite.

Jan 1, 1972

By G. R. Lane, A. Vermeulen, S. van de Venter, S. Bhoowanpursadh

Over the past two years Anglo Platinum made use of the specialist skills of Cyest Corporation to develop a Mine Optimization Tool (MOT) to enhance the current suite of in house mine planning tools and processes. The application was built in a multidimensional modelling environment developed by Cyest called CarbonL. This has allowed complex modelling that is transparent to the business users and therefore is not prone to the ?black box? approach that generally exists with these types of complex tools. The purpose of the MOT is to have an integrated software tool that can schedule production activities by half level for a shaft complex, while at the same time integrating the economics concomitant with that schedule. The tool allows the user to configure all activities relevant to the selected mining method, define the mine design parameters and geological parameters, define scheduling rules and then schedule all activities. This allows the user to test various production strategies and schedules very quickly and easily in terms of shaft value, costs and revenue profiles, labour complement and production ramp up so as to determine the option that best fits the overall strategy. This allows assessments of multiple scenarios in a relatively short period of time, after which only the best option is taken forward for graphic design and scheduling. This paper discusses briefly the rationale behind the Mine Optimisation Tool and the underlying workings of the modules that comprise the tool. It also covers the life cycle of this tool from the original prototype through to the final Mine Optimisation Tool software and discusses the positioning of the final tool.

Jan 1, 2007

By D. Harrington

Correct ventilation of underground workings whether in coal or in metal mines consists in establishing such control of air currents that the miners may work in safety, with maximum comfort and efficiency, and without impairment of health; also in controlling the air flow so that the mine workings may at ordinary times be kept reasonably free of harmful gases or dusts, and so that in time of emergency, as when a fire or an explosion occurs, there may with minimum delay be maintained as much or as little air flow as is desired throughout the mine in its entirety or in certain parts of the mine. Control of air flow is the essential point of any mine ventilating system, and is obtained only by the installation of mechanically operated fans, and other ventilating devices such as doors; overcasts, regulators, etc. Every mine, large or small, coal or metal, should from the outset be equipped with a fan. Much has been written about natural ventilation, and many claims have been made that in specific mines or parts of mines there is sufficient natural air flow. As a matter of fact, there are actually very few if any mines, coal or metal, where natural ventilation creates atmospheres anything like adequately safe or healthful for underground workers even at ordinary times or under ordinary. conditions; and at the time of a fire or an explosion mines depending upon natural ventilation are practically helpless, and are decidedly dangerous for the unfortunates forced to be in them either at the time of the disaster or afterwards when trying to handle conditions arising from the emergency.

Jan 1, 1929