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By AIME AIME

Russell B. Paul, Chairman of the Special Committee on Divisional Relationships, presented the interim report of his Committee which was published in the September, 1945, issue of MINING AND METALLURGY and a copy of which is incorporated in the official minutes of this meeting. The following specific actions were taken by the Board of Directors in relation to the six recommendations in the Summary of the Report as published: (1) Mr. Haider, Chairman of the Petroleum Division, presented the formal request of his Executive Committee that the headquarters of the new Secretary of the Petroleum Division be established in Dallas, Texas. After lengthy discussion in which the point was made that the success of this program would depend upon effective co-operation between the Chairman of the Division, the Secretary of the Petroleum Division, and the Secretary of the Institute, the request was approved. The new secretary will be selected by the Division and will be employed by the Institute in the capacity of an Assistant Secretary. (2) The following item in the report was approved:

Jan 1, 1945

By J. H. Ahn, J. K. Yoon, Jung-Eui Lee

"A concentration change during grade transition operation in steel thin slab casting is predicted with computer simulation, water model and plant trial. Fluid flow and mixing patterns in various tundish levels and flow rates were analyzed through three-dimensional mathematical modeling. Comparing with water model experiments, a simple, efficient and accurate computational model has been suggested to predict the concentration profile at outlet of tundish. Based on the model, mixing in/below the mold was analyzed considering EMBR. The predicted concentration profiles show good agreements with the measured values. It is found that the lower vortices in the mold are suppressed by the electromagnetic field and the plug-like flow region develops which decreases the intermixing of two different grades of steel and shortens the length of transition region.1. IntroductionContinuous casting is the primary mode of production of semifinished steel products as it offers tremendous advantages in terms of energy savings, increased yield and higher productivity over the traditional ingot casting process. Efforts have to be made constantly to improve the quality of the cast product, reduce costs and thus increase the competitiveness of the steel manufacturer. One way of reducing costs is to reduce the amount of intermixed steel during the grade transition operation.Several different procedures exist to handle the casting of dissimilar grades for the conventional slab casting. Each procedure has its own merits and demerits. In order to choose the best method for a particular operation, there are a lot of researches. In the case of present continuous thin slab casting of POSCO mini mill, the only possible method is to change ladle during the grade transition. Due to the high casting speed (3.8m/min-4.4m/min) it is impossible to change the tundish and due to the thin thickness of slab it is also impossible to insert grade separator."

Jan 1, 2000

By J. W. Walkiewicz

Studies were conducted by the Bureau of Mines to develop a method for fabricating Sm-Co permanent magnets. This method consisted of arc-melting, crushing and grinding the alloy, alining and pressing the powder, and sintering the green compacts. Results indicated that the optimum composition was 36.7±0.3 weight-percent Sm and 63.3±0.3 weight-percent Co. This composition was obtained by blending together Sm2C07 and SmCo5. The maximum values exper¬imentally obtained were MHC = 27.4 kOe, BHc = 7,510 Oe, Br = 7,810 G, and (BH)max = 15.1 MGOe. The optimum sintering temperatures and grinding times for maximum MHc and (BH)max were determined. Lowering the grinding temperature from 0° C to -60° C resulted in a significant increase of magnetic properties.

Jan 1, 1973

By Balladares V. Eduardo

Most of the arsenic contained in copper concentrates is removed in the gas phase during the smelting and converting processes and, according to recent environmental regulations, it is required to fix it in a solid stable form. In this regards, ferric arsenate has been reported as thermal and aqueous stable compound. Therefore, various alternatives for treating gas containing arsenic were considered in this work. From data obtained at laboratory scale on fixation of arsenic using iron oxide, a new process to treat copper concentrates containing arsenic was evaluated. The effect of temperature, oxygen potential and the sample porosity on the fixation of arsenic contained in a gaseous stream was studied, and the iron oxide converted into ferric arsenate was up to 10%. The obtained results suggest a new alternative for gas treatment with an interesting and attractive technical development. The arsenic was retained as ferric arsenate with thermal and aqueous stability, and it allows a safe disposal keeping the environmental restrictions. The kinetics parameters are used to scale up laboratory results to higher processing rates.

Jan 1, 2005

By M. M. Myers

"Importance pf the small stone problem.Profitable disposal of limestone too small for making lime in the shaft kiln, is one of the most urgent problems in the lime industry. Reports received by the Bureau of Mines from 31 quarries show that the proportion of small stone varies from 2 to 40 per cent, averaging 18 per cent of gross pro¬duction, Modern methods of heavy blasting, and the use of crushers in large quarries tend to increase the proportion of small stone above that produced in early days when light blasting and hand sledging were almost universally used. There is also a growing movement toward underground operation of lime deposits, a method which in general produces a greater proportion of fines than is encountered in open-pit work. Thus the small stone problem is of growing importance, and demands the attention of every progressive lime producer. As the problem is of almost universal interest, it is urgently desired that every operator who reads this report will contribute from his knowledge or experience, answers to the questions on the final sheet.There are several markets in which small stone may be sold but in these markets the competition is generally keen and the prices low. The lime producer's chief product is lime, he understands its manufacture and marketing, and brings him a greater return than can be obtained from most limestone by-products. For these reasons it is evident that the conversion of small into lime is the nest desirable means of disposal."

Apr 1, 1924

By Paul W. Weiblen, Louis J. Cabri, Rolando Lastra

"Preliminary tests were done to determine whether comminution by electric-pulse disaggregation, or E-PD (cf. Rudashevsky et al; 1995), was more effective than using conventional crushing for Merensky Reef ore. A hand sample of the Merensky Reef was sawn in two: then one sub-sample was comminuted to .2 mm using E-PD at the University of Minnesota, and the other sub-sample was crushed to .2 mm using a conventional jaw crusher at CANMET.The products of the electric-pulse disaggregation and jaw crusher were fractionated by sieving and by a separation using a heavy liquid with a specific gravity of 3.3, because the proportion of platinum-group minerals (PGM) and sulphides to silicate minerals is very low. Thus, four mineral separates were produced: .2000 + 833 µm, -833 +208 µm, -208-µm float and -208-µm sink. All the mineral separates were studied by image analysis (Lastra et al; 1998). The main objective was to determine the liberation of gangue (silicate minerals), chromite, pyrrhotite, chalcopyrite, pentlandite and PGM. In the case of the PGM, a specific image analysis program was written to search and measure these minerals.The results show that the liberation obtained for gangue was similar (~99%) using either method of comminution. However, the liberation obtained for chromite (~89% vs. ~38%), pentlandite (~50% vs. 1%), pyrrhotite (~56% vs. ~38%), and PGM (~56% vs. ~1%) by E-PD was higher than that obtained by conventional jaw crusher, whereas the liberation obtained for chalcopyrite (~20% vs. ~71%) by E-PD was lower. Nevertheless, the image analysis of the products also showed that the PGM are strongly associated with pentlandite. Thus, for the Merensky Reef, liberation of pentlandite from the gangue minerals and chromite is important to recover more of the PGM. This maybe be significant because, in addition to increased recovery of platinum-group minerals (PGM), Merensky Reef pentlandite also contains significant quantities of valuable platinum-group elements like Pd and Rh (Cabri, 1981; Cabri 1988, Kinloch 1982, Peyerl 1983). Hence, the results indicate that for the Merensky Reef, electric-pulse disaggregation would represent a better comminution operation than a conventional jaw crusher would. In addition, the greatly improved liberation for chromite may find application for the PGM-rich UG2 chromitite."

Jan 1, 2003

By Juan Francisco Mori, Miguel Ángel Aucapoma, Pablo Zevallos

En este artículo se describe el prototipo de un equipamiento instrumentado digital cuya función es monitorear la condición de los techos de los socavones para evitar que se produzcan accidentes por desprendimientos generados por el debilitamiento de las estructuras que sostienen los techos, debido al corrimiento de las estructuras del macizo rocoso. Básicamente el sistema informa mediante la activación de alarmas pre-configuradas al interior de mina, con el propósito de prevenir y evacuar al personal.

Apr 30, 2020

By J. Pelders, G. Nelson

"Fatigue is a significant concern in the mining industry as it is a causal or contributing factor in many incidents and accidents. Fatigue can be caused by work- and non-work-related factors. There is a lack of information about associations between demographic and other non-work factors, and fatigue. This study aimed to assess associations between demographic, work, living, and socioeconomic conditions, and lifestyle characteristics, and fatigue at a platinum smelter in South Africa. Eight interviews with management and two focus groups with production workers were conducted, and 75 questionnaires were completed by production and other workers. Both work- and non-work-related factors were considered to be causes of fatigue. These factors included overtime, shift work, high workloads, activities performed outside of work, age, race, housing tenure, diet, sleep disorders, stress, and job satisfaction. In general, higher levels of fatigue were reported by younger participants, those who rented accommodation, ate less healthily, had a sleep disorder, and those with high levels of stress and low job satisfaction. As various demographic, lifestyle, and wellness-related factors were associated with fatigue, both work and non-work contributors should be addressed in fatigue management plans. BackgroundFatigue may be defined as ‘a state of impaired mental and/or physical performance and lowered alertness arising as a result of, or a combination of, hard physical and mental work, health and psychosocial factors or inadequate restorative sleep’ (BHP Billiton, 2005). Williamson et al. (2011) define fatigue as a biological drive for recuperative rest. Sleepiness and fatigue are related, and the terms are often used interchangeably. However, sleepiness, more specifically, can be defined as sleep propensity, or a person’s tendency to fall asleep (Hossain et al., 2003; Shen, Barbera, and Shapiro, 2006).Increasing levels of fatigue and sleepiness are associated with lapses in attention, errors, response slowing, fluctuations in alertness and effort, and impaired attention, working memory, long-term memory, decision-making, and creativity (Alhola and Polo-Kantola, 2007; van Dongen and Dinges, 2000). Fatigue is also associated with adverse effects on mood and impulsive behaviours (Alhola and Polo- Kantola, 2007; Minkel et al., 2011; Schwarz et al., 2013). It is a significant concern in the mining industry as it is commonly identified as a causal or contributing factor in many accidents and injuries (Schutte, 2009). Fatigue can also lead to long-term health problems, including digestive problems, heart disease, stress, and mental illness (Shaw, 2003)."

Mar 1, 2019

By V. I. Lakshmanan

Wastes when produced can be reused or recycled prior to disposal. Industries that cause environmental concerns during manufacturing include primary materials and primary metals. Pollution prevention mechanisms to achieve waste reduction require new separation, reclamation, control and process simulation technologies. Substituting recyclables for virgin resources will reduce energy use, water pollution, air pollution, water use and mining wastes. Shrinking landfill space will spur new technologies for waste treatment and recycling. These situations hence offer opportunities for innovative flowsheets with appropriate separation technologies. Development of innovative flowsheets to treat recyclables offer unique opportunities for process/product development, obtain green products and hence market advantage. The paper will illustrate with selected innovative flowsheets to treat recyclables.

Jan 1, 1996

By Wen Xuan

Oolitic iron ores have significant economical importance because of their extensive resources in the world. However, their utilisation is often quite limited due to the high content of phosphorus inside. The phosphorus is often finely disseminated in the oolite structure and generally not liberated in the form of free particles. The iron ore used in this work is a typical oolitic goethitic iron ore with high phosphorus. The process of phosphorus removal from this ore is difficult because the phosphorus is not present as distinct minerals. As a result, no physical beneficiation process is able to separate the phosphorus from the iron bearing phases. The current concentrate contains low iron grade (Fe ~49%) and high phosphorus content (P 0.7~0.8%). The acid leaching is a potential way to dissolve phosphorus. Previous studies have shown that the thermal treatment makes the phosphorus more accessible for the acids and enables more efficient phosphorus dissolution. Some chemical additives are reported to enhance this phenomenon. A series of tests have been carried out using roasting - grinding - magnetic separation - leaching technologies to remove the phosphorus from this current concentrate. In the first stage, several tests were performed at pilot scale under the same conditions as described in some publications. The achieved results were similar to those from previous tests at laboratory scale. In the second stage, new test conditions were investigated in laboratory scale in order to achieve better result and to reduce the operational cost.

Aug 1, 2018

By C G. Ryan, D R. Cooke

The Thames gold-silver deposits are part of the Hauraki goldfield, situated within the Miocene to Pliocene calc-alkaline Coromandel Volcanic Zone (CVZ). The Waitangi vein system is one of the mineralised ore shoots in the Thames district. The Thames gold deposits are characterised by shallow-level epithermal vein mineralisation with phyllic to advanced argillic alteration assemblages and abundant sulphide minerals including pyrite, arsenopyrite, chalcopyrite, galena and sphalerite. Gold occurs as electrum in association with sulphide minerals. Sulphur isotope analyses of mixed sphalerite-galena and sphalerite-galena-chalcopyrite samples yield a narrow range of δ34 SCDT values (-1.0 to 0.9 ë; n=5), whereas late spongy pyrite gives unusually light sulphur isotope values (-16.7 to -27.9 ë; n=4). Vein quartz from the mineralised zone at Waitangi yields δ18OSMOW values from 6.8 to 12.7 ë (n=23). Fluid inclusion studies indicate a homogenisation temperature range of 190¦ - 296¦C and salinity range of 0.2 - 3.0 wt per cent NaCl equivalent. Similar temperature and salinity ranges have been recorded for the other gold deposits in the Coromandel Peninsula. PIXE (Proton Induced X-ray Emission) analysis revealed that the Waitangi ore fluids have 1090 - 2700 ppm K (average 1600), 145 - 205 ppm Ca (average 180), 80 - 100 ppm Mn (average 90), and 80 - 200 ppm Fe (average 120) but no detectable Cu, Zn, Br, Rb, Sr, Pb and Bi (only one fluid inclusion contains 28 ppm Zn). The sulphur isotopic values of base metal sulphides from Waitangi suggest that the sulphur was derived from a magmatic source (either directly, or by leaching of igneous sulphides). The calculated oxygen isotopic composition of ore fluids is between -2.1 to 3.8 ë at 250¦C and -0.1 - 5.8 ë at 300¦C. Oxygen isotope analyses have revealed significant variations in δ18O values with elevation and gold grades. Zones of gold enrichment coincide with a zone of variable oxygen isotope values at the top of the vein system, where boiling and/or fluid mixing most likely occurred. Mixing of ore fluids with convective ground water is a likely mechanism for gold deposition in a shallow environment for the Waitangi vein system and there is also lack of fluid inclusion evidence (eg liquid-rich and vapour-rich inclusions in the same growth zone) for boiling of ore fluids. Oxygen isotope values varying with gold grades within the Waitangi conduits suggest that δ18O values may be useful in targeting bonanza grade gold mineralisation in epithermal vein systems.

Jan 1, 1999

Rio Tinto Iron Ore (RTIO) manages eleven mines in the Pilbara region, Western Australia. Three of these mines have previously or are currently mining black shale that contains varying amounts of pyrite. Several new deposits currently being evaluated and existing mines that may progress below water table in the future, will also encounter this waste material. The black shale presents not just an acid rock drainage risk but also a spontaneous combustion risk. This paper presents the black shale management strategy and provides an overview of the relevant activities undertaken by RTIO. The strategy can be divided into two components which firstly involve defining the risk and secondly involve managing the risk. The mineral waste management plan is used to identify specific mineral waste hazards by:geochemical characterisation of waste material,undertaking mine site specific risk assessments,characterising the receiving environment,identifying sulfidic boundaries in geological and mining models,quantifying the amount of sulfidic material in medium and long-term mine plans, anddesigning and sequencing black shale waste dumps. Once a mine exposes black shale the Spontaneous Combustion and Acid Rock Drainage management plan is used and the major activities are: regular site meetings with a representative from every group that works with black shale;compliance with safe working procedures for site specific and detailed activities;regular training;the use of specific explosives to prevent premature detonation;ongoing geochemical characterisation;acid water management, monitoring and analysis;regular internal and external auditing of procedures and practices; andclosure planning assessments and preparations (ie cover trials, geochemical void modelling, geochemical waste dump modelling). The success of this holistic strategy is evident by the awareness of personnel within the business, thorough understanding of the geochemistry and by undertaking proactive management of black shale during mining. The strategy and management plans adopted by Rio Tinto Iron Ore have activities that other mine sites with potentially acid forming material may like to consider implementing.

Jan 1, 2009

By G. M. Potter

During investigation of the occurrence of manganese deposits in the western United States, the Bureau of Mines collected 2-ton samples of 4 ores from 3 properties in northeastern Nevada. Laboratory tests were made to determine the amenability of these ores to ore-dressing methods of concentration. The Caviglia-Vietti property is situated 11 miles southeast of Ely, White Pine County, Nev. The ore deposits are lenticular veins and irregular masses found in limestone fracture zones and along the contact of limestone and underlying shale. Two samples, of the ore were tested: Lot A, from the Vietti shaft, and lot B, from the. Caviglia shaft.

Jan 1, 1954

By Ahmad Mahboubi

The damage caused by catastrophic earthquakes has always been an incentive towards more sophisticated building codes and requirements. In parallel to computer technology development, the engineers? attitude towards acquisition of more accurate results is increasing. This approach leads to designation of structural elements with more elaboration considering different aspects of their behavior. In addition, less simplified methods will be considered as satisfactory for analyzing such problems. The problem of soil-pile-structure interaction is one of the phenomena that can be included in this category. In general, there are two methods by which the study of soil-pile interaction phenomenon is studied. These include direct and sub-structuring methods. The sub-structuring approach relies on the linear or slightly non-linear behavior of soil since it employs the results of kinematic interaction analyses for inertial interaction studies. In the past, the kinematic interaction between pile-soil was considered as negligible. This was due to the softer nature of the surrounding soil that increased the time period of vibrations. However, more research revealed that although this approach was consistent in many cases, there were some sites where the time period decreased. This was due to the material properties of the foundation and the soil, in a way that caused the frequency of vibration meet natural frequency of the system. The second type of interaction is the inertial interaction which reflects the effect a structure on top exerts on the oscillation experienced by the foundation. This paper examines the impact of vertical load on the inertial interaction by virtue of impedance functions. Three different load cases for the structure at the top of a pile foundation were considered for the analyses conducted in this study. The changes in the stiffness and damping of the system by frequency are studied and finally, the results are presented.

Jan 1, 2010

By Enguang Zhu, Kangning Zhang, Yang Li

"Due to the use of outdated mining technology or room and pillar mining process in small coal mines, the coal recovery ratio is only 10% - 25%. In many regions of China: the damage area caused by the small coal mines amounted to nearly one hundred square kilometers. Therefore, special mining techniques must be taken to reclaim the wasted resource in disturbed coal areas. This paper focuses on the different mining methods by analyzing the longwall panel layout and abandoned gateroad (AG) distribution in in the abandoned area of Cui Jiazhai Coal Mine in northwestern China. On the basis of three-dimensional geological model, FLAC- 3D numerical simulation was employed. The abutment pressure distribution was simulated when the panel face passed through the disturbed areas. The proper angle of the inclined face was analyzed when the panel face passed through the abandoned gateroads. The results show that the head end of the face should be 13-20m ahead of the tail end. The pillars on both sides of abandoned gateroads had not been damaged at the same time, and no large-area stress concentration occurred above the main roof. Therefore, the coal reserves of disturbed areas can be successfully recovered by using underground longwall mining. INTRODUCTIONDuring the 70-90's, there were a lot of small coal mines in China. Due to their disordered mining, most of the small coal mines left a great many abandoned gateroads (defined as AG in this paper) and a large area of damage coal seam. In these type of coalfields, there exist many mining risk issues, including nonuniform stress in the overburden, flooding and hazardous gases accumulated in the gob. So how to lay out a longwall panel and successfully mining under this type of abandoned small mines is a big issue nowadays in China.As mentioned above, longwall panel is being performed in the damaged coal seams in order to increase recovery of coal reserves (Wang, 2009). However, the abandoned geteroads intersect to each other all around the area. So a series of production issues arose while the panel face is passing through these AG. Gang and Gong (2015) analyzed the roof stability and abutment pressure distribution during the face was passing those AG that were parallel and inclined to the faceline. Xie, et al. (2015) proposed the ground control mechanism by passing the AG in top-coal caving longwall mining. He recommended to stop the face advance until the roof is over, using high strength bolts and cable bolts, and grouting consolidation. This paper studies the different mining methods by analyzing the longwall panel layout and AG distribution in damage coal seams. Theoretical analysis and field observation were conducted to determine the overburden movement when the face was advancing under the AG. The pillar between face and parallel AG changes from elastic to plastic and eventually to the residual supporting status. All these three status was combined with the roof structure to establish the theoretical model to calculate the shield support capacity. Numerical modeling was employed to simulate the pillar stability and determine the abutment pressure distribution as the face inclined to the AG during longwall mining."

Jan 1, 2016

By Zhiyong Gao, Ruiying Fan

"Crushing and grinding are the prerequisite processes in many industries, such as minerals processing and powder technology. During crushing and grinding, minerals will cleave or fracture along the directions by broken the interlayer bonds (e.g., ionic bonds), generating some commonly exposed surfaces. The broken (or dangling) bonds at the generated surface makes the surface more active and determine the reactivity of the surface. In this work, the population of broken (or dangling) bonds on commonly exposed surfaces of fluorite mineral (a chosen model mineral) was calculated. Based on the calculated broken bonds information, the anisotropic surface reactivity of fluorite such as surface energy, surface relaxation, dissolution, wettability, surface charge and adsorbability, were discussed. The results show that the surface broken bonds density, which is positively related to the surface energy, can be used to predict the cleavage nature, surface relaxation degree and surface stability of fluorite crystal. The distribution characteristic and the number of broken (or unsaturated) bonds of surface active atoms (like Ca for fluorite crystal) can be used to predict and explain the anisotropic wettability, surface charge and adsorption mode and strength of organic molecules on different commonly exposed surfaces. It is easy to conclude that the calculation of surface broken bonds can serve as a fast and accurate way to start the mineral chemistry studies. These findings will be helpful to the mineral/material chemistry research in related interfacial science communities.INTRODUCTIONGrinding for mineral liberation is a prerequisite for a successful flotation separation. Also grinding for size reduction is a prior process for a favorable powder technology. During the grinding process, the minerals / materials will cleave and fracture along certain crystal directions with relatively weak interlayer chemical bonds1 to form a number of common exposed surfaces. Exposed surfaces are the outer boundary of a solid substance. In the mineral / material block, the bonding orbital of the atoms is filled with electrons and the atoms are in a steady state. Atoms on these exposed surfaces appear to show dangling bonds (or broken bonds) by losing chemical bonds to adjacent atoms in the previous block. Therefore, surface broken bonds serves as an initial property of a fresh surface. The lattice arrangement and crystal orientations causes differences in the number of dangling bonds on each exposed surface, i.e., anisotropic surface broken bonds2. The anisotropic dangling bonds enable the exposed surfaces to show varying degrees of surface reactivity (including surface energy, surface charge, surface relaxation, dissolution, wettability and adsorption behavior), known as anisotropic surface reactivity."

Jan 1, 2018

By Sanford Belden

My topic, Recent Developments in the Design of Electric Mine Locomotives and Mining Machinery, does not require me to go into a general review of electricity as applied to the mining industry. Interesting as that subject always is, what I might say in regard to it, by way of introduction, would be unnecessary use of your time, since such facts are familiar to all. First, we will consider the recent development of the electric mine locomotive. We may well pause for a moment to reflect upon its importance to the coal-mining industry of to-day. With the dawn of the electrical age its advent was inevitable. Our practical interest is aroused not so much by the first crude effort as by the great efficiency attained during the 30 or more years since the electric locomotive made its first appearance. To judge accurately what it means to coal mining, and through coal mining to the industrial field at large, we would have to know how many of these locomotives are in use throughout the country and their aggregate daily performance, and then compare the results with what could be expected with other forms of power. Such data are lacking, but it requires no statistician to make it evident that the electric mining machine is a tremendous factor in modern progress, and that without it the work of the world could never have reached its present magnitude. Not only has the electric mine locomotive served its own special branch of usefulness, but incidentally it has solved in the main the whole problem of electric transportation. It is but a step from the triumph of a 25-ton locomotive leading a long train of loaded coal cars from a mine to the electrification of common carriers. We may or may not be near any great change in this respect. Economical reasons may hold it back for an indefinite period. But the fact remains that in the development of our mine locomotives we have met this larger emergency, in mechanical type and efficiency, whenever it may come.

Jan 6, 1914

By T. N. MacAuley

"The Ingerbelle and Copper Mountain deposits are located near Princeton in southern British Columbia. They are owned by Newmont Mining Corporation's wholly owned subsidiary, Similkameen Mining Company Ltd. The property includes the Copper Mountain mine, a former producer. Ore reserves recoverable by open-pit mining are estimated to be 76 million tons containing 0.53% copper. Production commenced during 1972 at a rate in excess of designed capacity (15,000 tpd). All of the known major copper deposits in this area lie in a 14,000- by 3,500-foot belt of Triassic volcanics (Nicola Group) that is situated between a well-defined syenitemonzonite- diorite stock on the south and a variable intrusive complex on the north. The Nicola rocks consist of andesitic tuffs and agglomerates with lesser amounts of flows and some lensy siltstone layers. The orebodies are essentially disseminated sulphide deposits, although fracture-fillings are also important in many areas. Total sulphide content is usually less than 5%. At lngerbelle, and at Pit 2 and most of Pit 1 at Copper Mountain, the sulphides are chalcopyrite-pyrite. In part of Pit 1 and most of the former underground mine they are chalcopyrite-bornite. At lngerbelle the predominant alteration associated with mineralization is a pale greenish-gray bleaching of the dark andesitic rocks. This has been identified as albitization, with lesser amounts of epidote, chlorite, biotite, scapolite and calcite. This bleaching is plentiful at Pit 2, but K-feldspathization is also evident here. These orebodies can better be classified with pyrometasomatic deposits than with typical porphyry coppers. Their relationship to intrusives, the probably extensive metasomatic replacements, the evidence of pneumatolytic activity, the formation and redistribution of magnetite, and the irregular distribution of mineralization are all characteristic of this class. Deep-seated faults probably acted as channelways for mineralization; fracturing, faulting and rock contacts influenced ore localization in detail."

Jan 1, 1973

By Atta Ur Rehman, Kwame Awuah-Offei

This paper examines the effect of bucket geometry (cutting-blade profile, floor profile and blade thickness), speed, motor power output and muckpile particle sizes on bucket penetration and draft for rubber tire loaders. The work uses a 1:16 scale model of a load-haul-dump (LHD) in full-factorial experiments to examine the effect of the variables on penetration and maximum draft. The results show that speed and motor output are positively correlated with penetration and draft, and muckpile particle size is positively correlated with penetration and negatively correlated with draft (p < 0.0014).

By J. A. Herbst

Fine coal cleaning by froth flotation has become common practice in the U.S. with more than 80,000 tons treated in this way per day. In spite of this large tonnage, developments in the automatic control of coal flotation circuits have lagged significantly behind those for mineral systems. One reason such developments have been limited is that instruments have not been available for the on-line measurement of carbon or ash and another critical variables in coal slurries. A second reason is that the influence of the operating variables on coal flotation has not been completely understood. During the last few years some of the required instrumentation has been developed and an improved knowledge of the flotation process itself has occurred through mathematical modeling; as a result certain control strategies for coal flotation are beginning to emerge. This paper attempts to evaluate several control strategies using a detailed flotation dynamic simulator, DYNAFLOAT. After constructing a process matrix for the system of interest, promising alternatives for linking manipulated and controlled variables have been analyzed. In order to develop combined grade and recovery control strategies, the authors found it necessary to construct a grade/recovery map with the aid of the simulator to drive the system to known final, feasible grade/recovery operating conditions. Finally, an advanced strategy which uses an on-line model to identify disturbances and take control actions is proposed.

Jan 1, 1983