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Gold mineralisation at the Macraes Gold Project is hosted in the Hyde-Macraes shear zone and can be traced for ~30 km along strike, although economic resources are confined to a seven kilometre section in the vicinity of the Macraes  township. The shear zone, which typically dips at a low angle (~20¦) to the NE, is bounded by an upper hanging wall shear and a lower footwall fault. Mineralisation occurs along the hangingwall of the shear zone as well as in low angle concordant shears and stockworks. Ore types include graphitic cataclasites with variable amounts of quartz veining, 'lode schists' and quartz-vein stockworks. Mine geology and grade control activities are designed to ensure accurate definition of ore and waste as well as the accurate prediction of ore grade. Grade control involves an integrated process of blast hole sampling, geological mapping and geostatistical modelling. Geological mapping is carried out post blasting by means of excavating trenches across are zones defined by assay data. Conditional Simulation is used to model raw assay data to define ore-waste contacts and estimate ore block grade, although, geologically defined contacts have precedence. Low angle ore zones impart a wedge shaped geometry to many ore blocks. These ore blocks are bounded by contacts that can be selectively mined to, thereby reducing misallocation of ore and minimising grade dilution.

Jan 1, 2001

By Zhang Jianliang, Zuo Haibin, Gao Bing, Wang Zhe

"As a result of the shortage of coking coal and the quality decrease of coke, it is important to know how to make better use of highly reactive cokes. The co-gasification behavior of highly and lowly reactive coke for blast furnace is investigated. The results show that: In the middle stage of reaction, the weight loss ratio of highly reactive coke reacted together with lowly reactive coke is higher than that of it reacted individually. However, the weight loss ratio of lowly reactive coke is lower. The weight loss ratio of highly and lowly reactive coke is almost the same as that of the weighted average. The scanning electron microscope analysis indicated that the reaction degree of surface and interior of lowly reactive coke is relatively uniform with the reaction time increased. And the reaction degree of surface of highly reactive coke is obviously higher than that of interior.IntroductionIn blast furnace iron making process, coke functions as heat supplier, reducing agent, carburizer and skeleton. With development of blast furnace iron making technology, the skeleton function of coke is becoming more and more important in requirements of large scale furnace and high pulverized coal injection. High reactivity coke is usually produced by cheap coal with bad quality, and is not good for blast furnace process. The reactivity of coke is mainly determined by the coals used, and the resource of good quality coking coal is limited and is non-renewable. In order to fulfill the need of blast furnace, a lot of research have been done to improve coal matching using new kinds of coal to enlarge resource, in which coking coal and fat coal are reduced, whereas low price coal with bad caking property are used to lower the cost, and this would inevitably increase the reactivity of coke [1-4] Blast furnace iron making would still be the main stream for a predicted future, and high reactivity coke would correspondingly be used more and more, so it has great importance to study how to use high reactivity coke in blast furnace."

Jan 1, 2013

By Rolf Christiansson, Daniel Johansson, Urban Åkeson, Henrik Ittner, Mats Olsson

"This paper presents two recent studies on the extent of blast damage after excavation in crystalline rock. The Swedish Transport Administration and the Swedish Nuclear Fuel and Waste Management Company (SKB) are both under regulations to limit excavation damage during construction of tunnels. SKB is also required to limit the Excavation Damage Zone (EDZ), as this could be a potential flow path for radionuclides in the planned repository for spent nuclear fuel. Presented in this paper are investigations of blast damage from three tunnel sites, a road tunnel, an experimental tunnel in Äspö Hard Rock Laboratory and an underground subway depot. As expected the fractures resulting from the bottom charge are both longer and more frequent then those mapped in the column charge. The results show that the requirement to limit blast damage according to Swedish regulations was fulfilled for the column charge at the three studied sites.1 INTRODUCTION The Swedish Transport Administration (TRV) and The Swedish Nuclear Fuel and Waste Management Company (SKB) have both recently completed studies related the extent of blast damage from modern explosives after excavation. SKB studies focused on blast damage from pumpable emulsion explosives for underground construction (Ittner and Bouvin 2015) and hydraulic connectivity in the EDZ (Ericsson et al. 2015). TRV had a broader focus with different types of explosives including blasting for both road cuts and tunnelling with pumpable emulsion explosives. Investigations by means of geophysics were also conducted (Olsson et al. 2015). High demands on perimeter control and excavation damage is usually required for underground constructions with a long operation time, such as public tunnels for transport or underground repositories for nuclear waste. This paper presents the findings of recent Swedish studies and aims to discuss the topic in a broader context."

Jan 1, 2016

By Gisell Sumaria, Mike Martos

La analítica avanzada permite analizar los datos (en tiempo real, históricos, no estructurados, estructurados, cualitativos, cuantitativos, etc.) para identificar patrones, optimizar indicadores, mejorar procesos, generar conocimientos para informar y, en algunos casos, resolver conflictos con una mínima intervención humana, es decir, automatizar decisiones. El proceso analítico ha demostrado ser un excelente aliado para la toma de decisiones, o inclusive, desde el origen hasta la decisión, control y seguimiento de resultados del proceso.

Sep 29, 2023

By K. A. Wheeler

To evaluate the effects on groundwater of a proposed in-pit disposal operation at an east Texas lignite mine, the local geologic, hydrogeologic, and geochemical features were thoroughly characterized. Resultant data were used in a flow and transport model (SWIFT) to simulate migration of the ash leachate. Computer simulations indicate that the leachate plume will travel 61-152 meters from the disposal area in 100 years after resaturation of the spoils. A 61-meter buffer zone of mine spoils without ash will surround the disposal area. The proposed landfill operation received regulatory approval and is currently operating as a Class 2 non-hazardous landfill.

Jan 1, 1994

By Daniel W. H. Su

Thick, massive sandstone present in close proximity of the mining horizon can create difficult longwall caving issues, which may lead to severe face loading and subsequent face roof control problems. Under deep cover, such delayed caving and overhang not only impose additional loading on the gate road pillar system, but they also increase the potential for large seismic events. Such a combination of thick, massive sandstone geology and deep cover was present over a portion of a southwestern Virginia coal mine, which was confirmed via detailed in-mine roof scoping and mapping. Large seismic events were recorded over a district of 1,000-foot-wide longwall panels. This paper presents the ground control design changes implemented to reduce longwall-induced stresses in the sandstone, to reduce longwall abutment pressures in the gate road pillars, and to reduce the magnitude of mining-induced seismic events. A series of two-dimensional finite element models were constructed and analyzed to evaluate the longwall-induced stresses in the sandstone above the gate road pillars and the abutment pressures within the gate road pillars. Results from the analyses indicated that reducing the panel width from 1,000 to 700 feet reduced the longwall-induced stresses in the sandstone by a factor of 2.0. Specifically the probability of sandstone stability improved from 29% for the 1,000-foot-wide panel district to over 95% for the 700-foot-wide panel districts. Also, the subcritical 700-foot-wide panel, coupled with a change in pillar design, considerably reduced the longwall-induced abutment pressures in the gate road pillars, which significantly increased the gate road pillar stability factor. Surface subsidence measurements conducted over the 1,000-foot-wide panel district and two new 700-foot-wide panel districts were in very good agreement with those predicted by the finite element models. In addition, results from the models indicated that wider panels with a smaller district may produce the same probability of sandstone stability. One four-panel district and one five-panel district with the new ground control design changes have been mined successfully. The panel width was found to be the most influential factor in determining the longwall-induced stresses in the sandstone and in the gate road pillars. The thickness and massive nature of the sandstone, the proximity of the sandstone, and the strength of the sandstone were also found to be important factors. Seismic monitoring over the two mining districts that employed 700-foot-wide panels confirmed the reduction of one order of seismic magnitude when compared with those measured over the 1,000-foot-wide panel district.

Jan 1, 2014

By R. S. McCaffery, D. E. Krause

There has been some discussion among blast-furnace operators regarding the relative merits of tuyeres of the converging type and tuyeres designed in an attempt to produce a diverging jet of air. An article1 on Progress in German Blast Furnace Practice indicates the interest in this subject abroad. This article illustrates a diverging type of tuyere which is shown here in Fig. 1A. The design appears to be rather poor as regards known properties of air flow. The adoption of this tuyere, the arlicle states, resulted in a decrease of blast pressure of about 4 Ib. per sq. in. and an increase of the output of the furnace. If the improvements mentioned are due entirely to the change in tuyere design, the subject of tuyere design seemed worthy of investigation and this paper is a report of such work. Because of the gain in efficiency brought about by the use of a diverging tuyere in the German plant, it was thought desirable to investigate the shape of the air streams issuing from various types of tuyeres to ascertain whether the gain was due to the tuyere itself or to the distribution of the air in the furnace. Since it is difficult to do experimental work on a full-sized furnace, or even on full-sized tuyeres, and because of the equipment available for the work, it was decided to carry out the work on scale models of tuyeres. Therefore, in this work, single tuyeres were used and the blast discharged into the atmosphere. The shape of the air stream was determined by means of a Pitot tube suitably supported in the air stream at various positions. The air was furnished by a Roots blower driven by a 10-hp. direct-current motor having field control, and capable of discharging 250 cu. ft. per min. with a pressure on the discharge of 4 in. of mercury. A modern blast furnace with 21-ft. hearth requires about 50,000 cu. ft. per min. of free air at from 16 to 23 Ib. per sq. in. pressure, depending upon the type of burden. This pressure is the total pressure required to force the air through the burden and through the tuyeres. Upon computation the pressure drop through the tuyeres is about 1 to 2 lb. per sq. in. By making the tuyeres to a one-fifth scale, and by using a pressure of 1.5 in. of mercury, the shape of the air streams should be

Jan 1, 1931

By A. A. Beard

ABOUT three years ago, I. L. Dunn, of Marietta, Ohio, found that wells could be cleaned by blowing with compressed air; this method has been used with great success on many wells in the Marietta, Ohio, district, where compressed air is being used to increase production, by forcing oil through the depleted sands. About a year ago, the process was successfully used to clean out wells in the Lenapah pool in Oklahoma, where an air plant had been installed, under the supervision of I. L. Dunn. Wells from 900 to 1000 ft. deep, with 40 ft. of sand and cavings in them, were cleaned out in from two to three days. The use of this process had, so far, been limited to properties using the Smith-Dunn process, where compressed air, under suitable pressure and volume, was available. For other properties, a portable compressor seemed essential; this was built and successfully demonstrated by Mr. Dunn, for the Tidal Oil Co. in September, 1924. The process of cleaning out with air has been described.1 It consists of lowering the tubing into the well, with a shoe or nipple of heavy pipe substituted for the perforated anchor on the bottom. Into the tubing, compressed air is introduced through a rotary swivel hose at the top, or by means of swing connections. The tubing is lowered to the top of the cave to be cleaned out, several barrels of water are put into the hole, and the compressed air is turned on. This blows out the material between the casing and the tubing, the tubing being lowered as the material is removed.

Jan 9, 1925

By D. R. Gibbons

This morning I would like to speak to you about an area of chemistry that is enjoying a revival-organometallic compounds. This renewed interest, principally stimulated by defense needs, has already created new markets for the products of the mineral industry. Although the consumption of metals in these new products is modest at oresent, several hold promise of importance. Because this is a new and growing market, I am sure the Council of Economics is aware of many of its facets and is interested in new developments. Of course, the chemical industry has been a significant consumer of minerals for many years. I estimate that in 1957 the chemical-industry purchased a total of $1175 million worth of minerals as raw materials (not including fuels). This estimate can be broken down as follows: [Metals and metallic minerals $375 million Nonmetallic minerals (excluding hydrocarbons ) 330 million Hydrocarbons 470 million $1175 million]

Jan 1, 1958

By I. A. Ibrahim, A. K. Ismail, A. A. I. Afifi

"Synthetic rutile for paints industry is conventionally produced by a combined smelting and leaching process. Smelting process is an energy intensive step and represents economic burden in view of the increasing energy costs. Egyptian ilmenite ore containing 40% TiO2 and 38% total Fe was thus directly leached with sulphuric acid to produce eventually synthetic rutile. The process-involves digestion of the ore with sulphuric acid whereby both TiO2 and Fe are dissolved. The solution was then treated with iron powder to convert Fe3+ to Fe2+ to avoid co-precipitation of iron during the hydrolysis step. After solid/liquid separation and clarification, Fe was crystallized as ferrous sulphate hydrate by chilling. The titanium pregnant liquor was concentrated by evaporation and then hydrolyzed to precipitate hydrated titanium dioxide which was then calcined to produce synthetic rutile containing 98.6 TiO2 and 0.58% Fe2O 3. The optimum conditions of all the processing stages were determined.IntroductionSynthetic rutile for paints, welding rods and other industries could be produced from ilmenite ore by sulfuric acid leaching process. This process is a batch process and nearly 80% of all TiO2 produced in the world is made by this process [1]. Figure l shows simple block flowsheet of the process. The process involves the following stages.Digestion: In this stage, ilmenite ore is treated with concentrated sulfuric acid where both iron and titanium are converted to their respective sulfates according to the following equations:"

Jan 1, 2000

By R. M. Cunningham

Asarco operates one of the largest individual copper electrolytic refineries in the world at Amarillo, Texas. The feed for this refinery is a mixture of anodes produced at Asarco smelters and copper purchased t?om a number of primary and secondary sources. The variation in feed makes it imperative that the refinery practices state-of-the-art quality control to minimize the effects'of unwanted impurities in the electrolytic refining process. In late 1993, a plant designed to sigru6cantly reduce the antimony and bismuth levels in the electrolyte was commissioned. The purification plant uses ion exchange technology in conjunction with a novel strippiing system developed by Zeneca Specialties (U.K.). The strippiing system permits the recycling of the eluant and thus avoids the extremely high costs of stripping with conventional reagents. In addition, the environmental impact of treating the eluant for recovery of antimony and bismuth is minimized. This paper outlines the development of the technology and, in particular, describes the operational practices and improvements at Amarillo since the commissioning of the plant.

Jan 1, 1997

By N. Arbiter

Evidence for the floatability of sulphide minerals without collector is analyzed and it is shown that results obtained with ores, in contrast to those with single minerals or mineral mixtures, depend on many additional variables, some identified and others not. Because of the prevailing low levels and costs of collectors for most sulphide ores, it is unlikely that collectorless flotation will have commercial applications, so that continued research on the subject may be justifiable on theoretical but not on practical grounds.

Jan 1, 1993

By Sam F. Harrison

The National Board of Boiler and Pressure Vessel Inspectors again sends out this recommendation: If you have an air compressor that is mounted directly on the air tank, get it off. Characteristically, small- to intermediate-sized air receivers are thin-walled vessels, and as such are prone to failure when subjected to external loading. Many of these vessels, if not a great majority, are bought by a distributor of air compressor systems, who provides the compressor, motor, switchgear and other accoutrements-all of which are very frequently mounted on a base which is then welded to the shell of the receiver. These welds at the points of attachment transmit external loading to the tank in the form of weight and vibration, frequently resulting in stress-induced cracks.

Jan 3, 1978

By Mike O'Drisooll

There is no doubt, if any existed, that the commercial minerals world has now moved into a new era of unprecedented challenges in the sourcing, mining, processing, trade and use of industrial minerals. Industrial (nonmetallic) minerals remain the often unsung workhorse of mineral commodities and specialist raw materials that frankly keep the world’s manufacturing industries ticking over, and everyday products we use in sound availability. They are also very much present among the so-called “critical minerals” necessary to advance cutting-edge developments in growing high-tech markets such as in energy transition: for example, lithium, rare earths, graphite and fluorspar. Indeed, in the United States during 2024, industrial minerals again accounted for the majority share of total sourcing, and, yes, geopolitics. The last few years have witnessed a series of geopolitical issues that have impacted and continue to impact international trade in industrial minerals. Above all, it has been the threat and implementation of recent trade tariffs between countries that have been most damaging in creating a potential trade war. mine production by value at $72.1 billion, or 54 percent, followed by metals, 25 percent, and coal, 21 percent, according to the latest data from the U.S. Geological Survey (USGS). But right now, “industry resilience” seems to be the rallying call, with industrial mineral producers and traders facing straitened times from market slowdowns; environmental regulations; decarbonization and other sustainability issues; pressure to diversify; and near-shore mineral sourcing, and, yes, geopolitics. The last few years have witnessed a series of geopolitical issues that have impacted and continue to impact international trade in industrial minerals. Above all, it has been the threat and implementation of recent trade tariffs between countries that have been most damaging in creating a potential trade war.

Jul 1, 2025

By Richard J. Finno

This paper presents an overview of methods that can be used to predict damage to buildings as a result of excavation-induced ground movements and describes an adaptive management approach for predicting, monitoring, and controlling excavation-induced ground movements. Successful updating of performance predictions depends equally on reasonable numerical simulations of performance, the type of monitoring data used as observations, and the optimization techniques used to minimize the difference between predictions and observed performance. This paper summarizes each of these factors and emphasizes their inter-dependence. Case studies are presented to illustrate the capabilities of this approach. Examples are given to show how optimized parameters based upon data obtained at early stages of excavation can be used to predict performance at latter stages, and how they can be applied to other excavations in similar geologic conditions.

Jan 1, 2010

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

1 14 THIS IS A DIGITAL COMPUTER SIMULATION OF THE VENTILATION SYSTEM OF A MINE LOCATED IN WASHINGTON COUNTY, PENNSYLVANIA. THE VENTILATION SURVEY ON WHICH THIS SIMULATION IS BASED WAS RUN FROM OCT. 27-30 AND ON NOV. 2, 1976 IN THE ACTIVE PORTION OF THE MINE INBY COMBS SHAFT AND THE INACTIVE PORTION AFOUND AND INBY DONAHOO SHAFT. FOLLOW-UP SURVEYS WERE THEN RUN ON FEB. 18 AND FROM MARCH 7-11, 1977 TO INCLUDE THE MAIN HAULAGE SYSTEM OUTBY THE ACTIVE AREAS OF THE MINE. ALL SURVEY DATA WAS NORMALIZED TO A STANDARD DENSITY OF 0.075 POUNDS/CU.FT. PRIOR TO THE CALCULATION OF INPUT PARAMETERS FOR THIS SIMULATION. IN THIS RUN, THE ORIGINAL VENTILATION NETWORK HAS BEEN MODIFIED TO INCLUDE NEW INTAKE AND RETURN AIRSHAFTS AT THE WEST MAINS. IN ADDITION A CONNECTION HAS BEEN MADE BETWEEN THE MINE UNDER STUDY AND A SHAFT IN A WORKED OUT MINE IN THE 1 FACE AREA. THIS SHAFT IS CONSIDERED AN INTAKE SHAFT FOR THIS RUN.

Jan 1, 1977

By Maria I. De Rosa

The U.S. Bureau of Mines conducted experiments for predicting materials' ease of combustion (smoldering onset, smoldering, flaming, and decomposition rates) by means of submicrometer smoke particle characteristics for the development of a simple test method. The experiments were carried out in an approximately 20-L furnace, with a 10-L/min airflow through the furnace for a 14-min duration, at set furnace temperatures of 150°, 250°, and 1,000° C. The variables studied as a function of time were the onset time of smoke particles, time and duration of maximum smoke particle generation, average concentration of smoke particles, and particles' average diameter, mass weight loss, and furnace temperatures. Results show that the onset time of smoke particles is predictive of materials' ease of smoldering, and the time of maximum smoke particle generation and its duration, coupled with mass weight loss, are predictive of materials' ease of smoldering and flaming (depending on the experimental temperatures), and decomposition rates.

Jan 1, 2010

By A. Wahab Khair, N. P. Reddy

"Abstract. This paper attempts to characterize coal breakage due to the action of a continuous miner. Coal blocks with an approximate dimension of 45.7 cm x 38.1 cm x 15.2 cm (18 in. x 15 in. x 6 in.) were first subjected to confining pressures equivalent to in-situ conditions. Then the blocks were cut along the face/butt cleat direction by the cutting head of a specially designed unique automated rotary coal cutting simulator (ARCCS), simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-sit and operating parameters a number of other para¬meters such as 1) penetration of bit into coal, 2) penetration resistance (thrust and cutting pressures), 3) rotating velocity of cutting head, and 4) acoustic emission activity in the coal block were monitored. After each cutting cycle the fractured surfaces were photographed and a velocity survey was conducted by using a sonic technique. At the end of each experiment, the coal fragments were collected in bags using a vacuum cleaner. These fragments were then sieved for size distribution analysis.INTRODUCTIONThe Federal Coal Mine Health and Safety Act of 1969 was enacted to emphasize to coal operators that the airborne respirable dust should not exceed 2 mg/m3, thus reducing the incidence of coal workers pneumoconiosis.Dust control techniques such as conventional water sprays and dust collectors are only partially effective and require additional equipment expenditures. A more authentic approach would be to reduce respirable dust at the source the continuous mining machine cutting head, where the fragmentation process occurs. Improving the fragmentation process by characterizing the coal breakage will not only reduce respirable dust at the face, but it will also decrease the amount of respirable dust that is liberated during the secondary handling.Fragmentation of coal can be expressed as a function of three major groups of parameters; namely, 1) coal properties, 2) in-situ conditions and 3) operating parameters. This paper deals with the characterization of coal breakage along both face/butt cleat direction as a function of machine operating parameters such as rate of advance, angle of attack, bit configuration, bit lacing (spacing and pattern) and bit speed at various equivalent in-situ pressures."

Mar 1, 1989

By Jarvis ST

Colliery spoil is the major constituent of colliery spoil 'rockpaste' which has been used to infill abandoned limestone mines in the West Midlands of England since the early-1980s. The other constituents of rockpasle are pulverised fuel ash, lime and water. A key property of the rockpaste is its ability to flow within the mine workings over considerable distances before setting. This paper describes the work carried out to identify suitable sites as sources of colliery spoil for making rockpaste and goes onto consider the flow properties of the material and the monitoring methods used on-site. A full-scale trial comprising mulling a 6600 nt' section of an abandoned mine was conducted prior to the mulling of the Littleton Street Mine which had a volume of about 500 000 m'. As well as describing the methods used for monitoring the movement of rockpaste material, a description is also given of a dip-meter developed specifically for the purpose of measuring the level of paste in the mine. This paper shows how a colliery spoil based paste has been successfully rued for infilling abandoned mine workings. The monitoring systems developed for use in the two case studies presented in this paper are now being used extensively for infilling other abandoned mine workings. To-date over I I mines with a total volume exceeding two million cubic metres have been backfilled.

Jan 1, 1998

By John Stoten

"The 1980s have proven extremely difficult years for many resource-based organizations. Mining companies have learned how to weather the negative effects of inevitable economic cycles. However, with some notable exceptions, such as gold mining companies, the mining industry has faced a broader and deeper round of cutbacks than any experienced since the 1930s. Downsizing has been a major issue for many mining companies as they have faced the need for dramatic staffing cost reductions in the recent past.The continuing current rapid rate of change in technology and the marketplace, coupled with increasing merger and acquisition activity, will provide an on-going need for some companies to face major reorganization. This inevitably will involve down-sizing activity in some instances.Given this scenario, it is worth reviewing the industry's past experiences to identify approaches and techniques that could prove of value in handling a future staff downsizing challenge. This paper is based upon a downsizing consultant's experiences with the mining industry and other sectors, and highlights what appear to be key staff reduction planning and process issues.Planning for DownsizingA review of companies' downsizing activities of the last few years reveals four key activity stages which need to be addressed to ensure a successful transition. These stages are:1. organization planning;2. developing cost reduction strategies;3. implementing downsizing; and4. building for the future.A business situation that is severe enough to require drastic staff cuts typically affects all aspects of a company's operations. Most mining companies have reviewed cost efficiencies in many operational areas. However, these reviews often have been short term in focus . As a result, some companies have experienced multiple downsizing; each event a response to an immediate economic threat. This has sometimes resulted in an unstable organizational environment, with severe stresses on staff morale and productivity.In the long term it is more efficient and less stressful to the organization to adopt a more comprehensive and longer-term strategy. Especially in capital intensive mining operations, it makes sense to review all areas of business activity, not just staffing."

Jan 1, 1989