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By M. L. Rizzone

Since time immemorial, Mother Nature has been transporting slurries with both air and water serving as the carrier medium. Consider for example the formation of the continental shelves off our coast lines which are being formed by rivers emptying erroded land surface and depositing it into bays and gulfs. As the erosion processes take place, the fines are suspended in water which flows in streams and rivers and deposits where the velocity of the flow reduces sufficiently to allow the fines to settle out. The same process in some crude form is provided when one hoses his driveway or patio and moves dirt so as to provide a cleaning action. These examples illustrate rather crudely how the formation of slurries allows for the transport of solids. In recent years, this mechanism has become fairly well understood and slurry pipelining of many materials is now a vivid reality. The movement of liquids in pipelines necessarily occasions the use of pumps for the purpose. Those of us who have had some rub with the petroleum industry are familiar with the transport of solids through mud pumps and cementing and fracturing pumps where the movement of slurries is an everyday matter. In the drilling of an oil well the circulating fluid utilized to remove chips which are cut by a drill bit from holes drilled deep in the earth is called drilling mud. This substance contrary to what the name might imply is usually a fairly sophisticated material designed to develop certain characteristics which are desirable in the drilling process. The particles which have been cut by the drill bit are suspended in the moving column of fluid and brought to the surface and deposited. The separation of the cuttings from the drilling fluids is accomplished by the use of shaker screens and settling pits. However, it is impractical to remove the fines completely from the drilling fluid and as a result they are pumped through the mud pumps back into the circulatory stream.

Jan 1, 1969

By John T. Cumberlidge

The Groveland deposit, in the Upper Peninsula of Michigan, consists of an E -W trending overturned syncline of Middle Precambrian Vulcan iron formation. At Groveland, the Vulcan formation can be divided into four units or facies. The total succession may be more than 550 feet thick, and consists of a basal unit composed of a lean chemical quartzite with traces of magnetite; a non-banded, partly clastic unit characterized by the preponderance of hematite over magnetite; a transition unit of well-banded magnetite-bearing iron formation interbedded with non-banded oolitic hematite; and a well-banded magnetite-quartz silicate unit at the top of the exposed sequence. The present magnetite-hematite ratios of different units within the orebody are considered to be a primary (post-diagenetic) feature of the original sediment. Subsequent regional metamorphism has increased the grain size of the original iron oxide minerals, but did not appreciably alter the oxidation state of the original sediment.

Jan 1, 1964

By Milan Lipensky

This paper discusses the longwalling practices used at the San. Francisco Mine of Compania Minera Autlan in Mexico, in. the mining of a sedimentary, manganese deposit. Bethlehem. Steel Company is a part owner of this property. The San. Francisco Mine is located approximately 580 miles west of Mexico City, on the outskirts of the town of Autlan, in the State of Jalisco. The ore is shipped from the port of Manzanillo 120 miles southwest of Autlan. The mining method is a variation of the longwall retreat system, using friction. props that, until recently, had been used only in coal mining operations of Europe and the United States. However, due to the structure of the ore body and the modified longwall system that is practiced, there exists some unusual variations, such as: .1) friction props set by a mechanical two-step lifting device, 2) drilling and blasting, against the friction props, 3) a highly fractured and undulating, volcanic tuff roof; 4) displacement faults-up to 5 meters, and 5) a relatively stable, irregular floor.

Jan 1, 1964

By A. K. Clarke

In any treatment process that requires a coarse feed material to be reduced to a fine size by crushing and/or grinding it must be determined whether a wet or dry comminution system should be utilized. All factors must be evaluated in reaching the decision. Among these factors are: 1) Ecology and Plant Environment: Unfortunately in many instances the decision on wet or dry is based on prejudice resulting from an unnecessary fear of dust. The writers submit that this fear, although once justified, is no longer valid because technology and equipment is now available to collect dust to meet any standard. When dry grinding is used it is very often possible to discard a portion of the waste product in a dry state. This will decrease the size of the tailing pond required. As pollution control standards increase it becomes increasingly difficult to clean up water from tailing ponds. 2) Operating Costs: Steel wear is often five or more times greater in wet grinding than in dry grinding. This is mainly due to corrosion. The evaluation of the economics of dry grinding must of course include the air system and dust collection; similarly in a wet grinding plant related pumping and material handling costs should be included. Pumping costs are often overlooked. This assumes water is made to flow for nothing. Pumping can account for 20 percent of the power consumption in the grinding plant. Large scale comparative tests were conducted in a wet and dry commercial plant in 1970. The same ore was used for both tests. With all factors included in both plants the dry system showed lower horsepower per ton.

Jan 1, 1971

By Taeyong Lee, Cole Bales, Matt Fowler, John Horne

Mitchell Point Tunnel near Hood River, Oregon is one of the more unique segments of the Historic Columbia River Highway and State Trail being constructed through the Columbia River Gorge. This 650-foot bike/pedestrian tunnel set to open in 2024 is being delivered by FHWA in partnership with Oregon DOT, Oregon State Parks, and the U.S. Forest Service. Primarily driven using drill & blast excavation methods through basalt, the shotcrete and dowel-supported tunnel features masonry portals and ve window adits that provide illumination and views of the river similar to the original highway tunnel of many vistas built in 1915 that was removed in 1966 to make way for Interstate 84. This paper summarizes the planning, design, and construction.

Jun 23, 2024

By R. L. Godfrey

The Custom Coals advanced coal cleaning plant will be designed with a unique blending of existing and new processes to produce two types of compliance coals: Carefree Coal? and Self-Scrubbing Coal?. Carefree Coal will be produced by cleaning the coal in a proprietary dense media cyclone circuit utilizing fine magnetite to remove up to 90 percent of the pyritic sulfur and correspondingly greatly reduce the ash. While may utilities can achieve full S02 reduction compliance with Carefree Coal, others face higher sulfur reduction requirements due to the higher sulfur content of their existing fuel supplies. For these circumstances, a patented Self-Scrubbing Coal will be produced by taking Carefree Coal and pelletizing limestone-based additives with the finest fraction of the clean coal. These technologies will enable over 150 billion tons of non-compliance U.S. coal reserves to meet compliance requirements.

Jan 1, 1995

In some 35 years in the explosive and construction industries, we have probably seen the extremes in drilling and blasting practices. All of you know that it is difficult if not impossible, to separate those two operations, particularly when we are searching for an optimum. Early in my career while doing engineering survey work for a major cross country pipeline construction company, we witnessed some of the wildest blasts imaginable, and they were wild for two reasons. Both the drill hole diameter and the drill pattern were such that when loaded with explosives, the factor in terms of pounds/cu. yd. was extremely high. On the other hand, in 1982 we were in an underground coal mine where just one hole was used to prepare a 20-ft. (6m) wide face. In this coal mine, they brought down 7 yd3 (5.35m3) of coal with just 1 lb. (.454 kg) of explosive. On a pipeline job, the factor may only be .1 yd3 per lb. of explosives. Open pit operations in the same geographical area may have almost the same type of rock, but similarities could end there. The several operators over the years will have installed different size-crushing equipment or variances will exist in other facets such as drilling, excavating, and haulage units. That tells us that if we have 6 operations in that common area, we are faced with a fact that there is an optimum drilling and blasting pattern for each of those six. We start at that point. We will note from Figure No. 2 the simple equations for determining either cu. yds. or tons. For a rock heavier than limestone, it may require only 10 to 11 cu. ft. (.31m3) for 1 ton (.91 metric ton) of rock in place.

Jan 1, 1986

By Nathaniel Arbiter

The development of flotation machines since the first industrial use of the process can be divided into three stages. The first, up to about 1930, was marked by diversity in the means for contacting floatable mineral with the air/ water interface and for generating the interface, as well as in cell design. By 1927 Taggart (1) could list 170 patents covering flotation cells, and he mentioned dozens which were or had been in operation. He divided cells into eight categories according to design, type of separating interface, and where in the cell and how separation took place. These were: (1) Film or skin flotation with wet or dry oiling of surfaces; (2) pulp body process with bubbles generated chemically by pressure reduction, by vacuum or by boiling; (3) agitation-froth processes involving local supersaturation with air; (4) bubble column; (5) pneumatic; (6) cascade; (7) subaeration; and (8) combination and miscellaneous types and processes. Most widely used then were the agitation-froth, sub- aeration, pneumatic types. By 1943 a significant reduction in categories had occurred to the two main divisions of mechanical and pneumatic cells according to whether agitation and aeration were (a) by an impeller with or without compressed air, or (b) by compressed air alone. Cells at that time were still relatively small; the Morenci Concentrator completed in 1942 used 432 1.7m3 (60 cu ft) Fagergrens for roughing 45,000 and later up to 55,000 t/d.

Jan 1, 1979

By James Westfield

I welcome this opportunity to appear before you and to review briefly the various health and safety services of the Bureau of Mines available to the mining industry, other than coal, and also to tell of our plans for extending these services to improve safety and health conditions. The Bureau's health and safety activities are basically services by which we attempt to develop and disseminate information on improved techniques in mine accident prevention and promote mine safety education in the mineral industries. Unfortunately, some mining companies, particularly some of the smaller operations, seem to be unfamiliar with these services, The Bureau of Mines is charged by law with the responsibility for inspecting coal mines; other services to the coal mining industry and are provided only on request, Safety inspections and other services that we offer are provided for noncoal mining industries solely upon request.

Jan 1, 1958

By S. K. Ghosh

This paper discusses how the information on ash composition, ash-fusion temperatures, and ash-slag viscosity can be utilized to predict slagging and fouling potentials of a particular coal. A review of several empirical parameters which are commonly in use for determining such potentials is given. Also, some guideline values for interpreting the relative propensity of slagging and fouling of various types of coal are provided.

Jan 1, 1983

By X. Song, Q. Zhang

"The development of fracture zones in surrounding rock mass has significant impact on the stability of underground mine roadways. Detection of the fracture zones is of compelling importance for maintaining roadway stability as well as for safe and speedy excavation of the roadways. This paper presents a study conducted at Dong Bao Wei underground coal mine, where the roadways were developed in diabase rock mass. The roadways suffered severe damages, including sloughing and excessive floor heaving. The borehole imaging technique was applied in the study to observe and detect fracture zone development surrounding the roadway openings. Based on the borehole imaging studies, new roadway support systems were proposed to improve the stability. INTRODUCTION At the Dong Bao Wei Coal Mine three main roadways of the west wing were excavated. The three roadways had semicircle arch cross sections and were at a depth of 650 meters, each being about 750 meters in length. The roadways were driven through a section of thick diabase intrusion, which was softened by water with reduced strength and may turn into powder form under weathering. Site investigation indicated that the roadways in diabase intrusion zone were badly damaged due to severe deformation, and very serious roadway sidewall sloughing and spalling accompanied by severe floor heave often occurred.(Figures 1 and 2) In order to ensure the normal use of the roadway, undercuts were excavated. However, this operation seriously affected the roadway construction progress and increased the amount of roadway support operations as well as the roadway maintenance costs. Furthermore, a roof fall accident occurred in nearby drilling site. The investigation indicated insufficient support provided for the roadways which imposed significant safety hazards and would have serious impact to mining production and subsequent mining activities.The support of the main roadways is a critical task and is the focus of the underground opening excavation work at the mine, since more than 40 years of service life is required from these main roadways. For these roadways, large cross sections with high degree of stability and minimal amount of deformation should be maintained. Therefore, providing sufficient and appropriate roadway supports is of significant importance to the coal mine. In this paper, in order to optimize the roadway supporting system, studies were carried out on the geological structures, lithological characters, roof bolt anchoring features and suitable anchoring layers. The studies were aimed at ensuring the stability of mine roadways, reducing the roadway maintenance costs and providing a safe mine passageway for orderly production and progressive development of the mine"

Jan 1, 2016

By C. E. Jordan

The Bureau of Mines investigated a simultaneous elutriation and flotation technique for separating polyethylene terephthalate (PET) from polyvinylchloride (PVC). The Tuscaloosa Research Center, through a cooperative agreement with a recycling company, devised an elutriation-flotation method for beneficiating the mixed heavy plastics portion of municipal solid wastes which is composed of polystyrene (PS), PET, and PVC. A sodium carbonate brine was used to remove the lighter PS from the heavier PET and PVC. Over 98 pct of the PS was recovered in a high purity PS concentrate containing 99.7 pct PS, The remaining PET and PVC mixture was washed to remove the brine salts that would be harmful to the flotation process. The clean PET and PVC mixture was conditioned in a solution of 45 g/t gelatine and floated in a short (l-m) column flotation cell in an upward flow of water. In a single flotation step, over 75 pct of the PET was recovered in a high purity product containing 99.8 pct PET. The bubbles attached to the PET lowered the effective density of the PET-bubble agglomerate and allowed successful separation of these agglomerates from the PVC plastic pieces. This method separated two-thirds of the mixed plastics fraction into high purity PS and PET products suitable for recycling and left only one-third of the plastics in the mixed plastics product.

Jan 1, 1992

By Daniel E. Walsh

A pilot scale study was performed to evaluate the potential for gravity concentration of gold from -13 mm (-1/2"), crushed ore from Ester Dome, Alaska. 9.04 tonnes (9.94 tons) of crushed ore were sampled and processed through a Pan-American jig -Wifley table pilot plant. Plant products were sampled for assay and material balance calculations. Gold recovery through one stage of jigging and two stages of tabling was 17.4% at a concentration ratio of 615:1. Concentrate grade was 766.3 g/tonne (22.4 oz/ton). The feed grade to the plant was calculated at 1.71 g/tonne (0.050z/ton). Jig tailings, primary table tailings and secondary table tailings grades were 1.44 g/tonne (0.042), 1.30 g/tonne (0.038), and 5.47 g/tonne (0.16 oz/ton) respectively. Significant, coarse, free milling gold values were shown to remain in the jig tailings. Concentrate mineralogy is discussed.

Jan 1, 1991

By T. Gupta, T. Ghosh

"In recent years, the demand for Rare Earth Elements (REE) have grown rapidly due to increasing demand and global supply shortage. The supply deficit of these critical elements has encouraged the search for new sources of REEs, possibly Coal and Coal byproducts. Coals from certain parts of the world can be rich in REEs, and can approach a total concentration of 1000 ppm. Two Alaskan coal samples were investigated for the effect of size and density on the concentration of REEs on three selected size fractions. Flotation tests were conducted for finer fractions. Additionally Bottom ash and Fly Ash samples from a power plant have been examined for REE concentration. The results show that the upgrade potential for REEs on ash basis from whole coal basis ranges from 2:1 to 4:1 for Wishbone Hill and Healy coal samples respectively. Flotation of the finer fraction for both coal samples, conducted under similar conditions, reveal higher concentration of REE’s in the tailings. Both coal samples have a comparatively higher LREE content than HREE. Trends of REE content of the power plant products on ash basis revealed that Fly Ash has a slightly higher concentration of both LREE and HREE than Bottom Ash. Keywords: Rare Earth Elements, Coal, Coal Ash INTRODUCTION Rare Earth Elements (REEs) and their compounds are vital components in industrial, automotive, petrochemical, defense and medical applications. Dysprosium in combination with other elements is used in laser materials and nuclear control applications. Neodymium is present in magnets that are used in green power generation such as the manufacture of wind turbines and also in hybrid cars. Europium, Terbium and Yttrium are used for devices that have visual displays such as computer screens and laptops [1, 2]. REEs pose fewer environmental problems of disposal and recycling than conventional heavy metal counterparts [1]. Rare-earth metals are key ingredients for radar systems, avionics, modern national defense and satellites [2-8]. In the last 25 years China has been mining, processing and refining Rare Earth elements at affordable prices thus gaining a virtual monopoly in the market. The many fold rise of the prices of REE elements over the last few years and frequent disruptions in supply has forced various nations to invest in indigenous extraction of REEs by increasing production from previously productive sites and to expand the production from new alternate sources including coal and coal byproducts [9]. Coal and Coal beds have been found to be significantly enriched with certain critical metals and can be a potential source for both Light Rare Earth Elements (LREE) and Heavy Rare Earth Elements (HREE) [10]. Moreover, coals with high REE concentrations have been discovered in Pavlovka and Rakovka coal deposits in Russia, Appalachian deposits in USA, Sichuan Basin deposits in China and others across the globe [10-13]. A recent study from China looked at how different trace elements (including numerous REEs) partition in various size fractions of Antaibao coal from China. The finding indicates that the REEs, phosphorous, and thorium all have their high concentrations in the particle sizes 0.5 to 3 mm, and 6 to 25 mm. REEs are also often present in the form of phosphates such as monazite in coal [13, 14]. The objective of the study is to identify the concentration of REEs in Alaskan coals and to investigate the effect of density and size in the distribution of REEs in coal and coal byproducts."

Jan 1, 2016

By Philip Lindstrom

Retreat mining, using yielding steel friction props, over a seven-year period has been successful at a uranium mine operated by Hecla Mining Company in southeast Utah. The support system allow good roof control, maximum profit, complete extraction, and good ventilation. Unusual subsidence observations were made in that some of the surface was raised rather than lowered, Longwall mining, commonly practiced in European coal mines, has a potential of broader application because of mechanization possibilities and better roof control and ventilation at greater depths.

Jan 1, 1964

By Stephen W. Denton

Planning a mining operation in Alaska will involve the investigation of many parameters common to mine planning anywhere. However, there are some unique circumstances that must be recognized when one considers development of mining operations in Alaska. This paper will not attempt to provide a blueprint for mine planning in Alaska, but hopefully will provide a better understanding of the truly unique nature of the northern latitudes. Given this understanding, the mine planner can better assess the potential hurdles along the road to a successful mining operation. The regulatory trend towards uniform standards for mining throughout the United States exemplifies the necessity for Alaska to prove its unique position in the natural resources picture. The factors which make Alaska truly different from the "Lower 48" can be summarized by four points 1) Remoteness and Size 2) Seasonable Extremes 3) Geologic Immaturity 4) Vegetation and Wildlife

Jan 1, 1984

By Aydin Shaterpour Mamaghani, Cemal Balci, Nuh Bilgin, Mucahit Namli, Hanifi Copur

"It is expected that more than 10 Billion USD will be spent in Istanbul in coming years on tunnel boring especially with EPB-TBMs. However, the geology of Istanbul is very complex. Geologic formations changing from Paleozoic to Cenozoic ages cause tremendous problems due to frequently changed rock formations and andesite and diabase dykes. This paper summarizes a universal model to predict the performance of EPB-TBMs which is created upon the data base collected from several projects. The model first is based on predicting field specific energy and power consumed of TBMs using geo-mechanical properties of the excavated material and TBM diameter. Later net production rate is calculated using field specific energy and power consumed by TBM. A methodology to predict machine utilization factor permits to calculate daily advance rates. The validity of the model is tested using the data obtained from two recent metro tunnel projects. 1. INTRODUCTION It is expected that in a near future a total length of 400 km will be excavated in Istanbul in a complex geology. Selecting proper tunneling equipment, organizing an effective operational management with the right tunneling crew will be a major concern for an efficient scheduling of the future projects necessitating to create a model to estimate daily advance rates. Several TBM performance prediction models with few on the prediction of machine utilization time were realized in the past. However, there is quite limited number of research studies on predicting the performance of EPB TBMs. Specially predicting daily advance rates in complex geology, in mixed face, in fractured rocks, in transition zones etc. are in big concern (Namli et al. 2013, 2014). The first experiences in Istanbul with a gripper type TBM was a nightmare, roof collapses caused big delays in tunnel excavation (Bilgin 1993). A typical example to EPB-TBM was Kadikoy-Kozyatagi tunnel, changing TBM from opened mode to closed mode with few modifications on the cutterhead resulted a tremendous increase in the daily advance rates (Bilgin et al. 2009). The data collected from several tunnelling projects served a basis to create a model to predict daily advance rates of EPB TBMs. Within the frame of a research program the validity of the model was tested in Uskudar-Umraniye–Cekmekoy-Sancaktepe metro project and very recently in Mecidiyekoy-Mahmutbey project."

Jan 1, 2016

By Jon C. Jenkins

In order to plan the most efficient mine installation, a company should take advantage of all available information and tools. One of the first factors of a coal reserve that needs to be determined as accurately as possible is the quality of coal the mine will have access to during the life of the installation. With the aid of many types of well logs and computor analysis, we are investigating several methods of log correlation to determine such data as moisture, ash, sulphur, and BTU on an in place basis. It may be possible to determine this data more accurately in this manner than by using diamond drill cores for analysis and thus allow for a more profitable mine installation. The production of an underground mine is based on many factors, two of these being roof control and line water, where present either in the roof or coal seam. Using many of the same logs obtained from reserve and active mine areas, we have attempted to determine roof and floor characteristics such as strength, lithology, and moisture properties. Using data obtained from this program, we will make comments on possible length of bolt to be used, possible mining width, and pillar size as they would pertain to these reserves and active mine areas.

Jan 1, 1969

By Marcel Laflamme, Sebastián Ibarra‑Gutiérrez

Improvement on controlling the stope limits has enabled the assessment of technical performance in several underground mining operations. Technical performance, integrated to stope geotechnical and geomorphological parameters, constitutes the basis which guides mining engineers in the Mineral Reserves Estimation process. Moreover, there are established definitions to report this information in Canada, incorporated in NI 43–101, which stipulates that “A Mineral Reserve includes diluting materials and allowances for losses that may occur when the material is mined” [1]. However, some loopholes have been identified regarding practical standards followed to specify the way to include and report ore losses when the lost material was blasted and must be left behind unrecovered inside the stope. In fact, general efforts to estimate and quantify the negative effects of operational ore losses only consider under-break ore loss. However, mining engineers frequently confront situations requesting the anticipated closure of a stope. Therefore, reconciliation process should reflect the amount of unrecovered Mineral Reserve. This work presents a discussion of possible practices to integrate adequately operational ore losses consisting of blasted but not recovered material and focuses on how different approaches regarding the material constitution could severely affect the stope technical performance interpretation.

Aug 9, 2021

By Richard D. Lang

The paper provides an overview of the activities which culminated in the decision to construct a major diamond mine in the north west of Australia. It presents a broad summary of the geological, mining, processing and marketing work which has been required to bring the project to the construction phase. The implications of the development for the world industrial diamond market are also discussed.

Jan 1, 1985