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By Terry S. Maio

In 1978, Ozark Lead Company made the decision to expand the capacity of its mine/mill complex by 33%. The objectives of the expansion were to (a) increase mine' production capacity by 1816 tonne/d(2000 TPD), (b) increase lead metal pro¬duction by 21,790 tonne/y (24,000 TPY) and to (c) construct new facilities and/or modify exis¬ting equipment to accomodate the increased pro¬duction. The intent of this paper is to give a brief explanation of the equipment installed and the overall production and metallurgical benefits-realized from this expansion. The expansion was completed in the second half of 1980 with all equipment debugging and fine tuning completed by the first' quarter of 1981. The concentrator modifications and improvements were basically restricted to four areas: (1) materials handling, (2) automation: of the mill grinding circuit, (3) the increase of flotation capacity, and (4) concentrate dewatering.

Jan 1, 1983

By Timothy O’Rourke, Karrie Buxton, Chris Lynagh, Daniel Dobbels, Frederick Vincent

The Doan Valley Storage Tunnel Project in Cleveland Ohio was constructed to control Combined Sewer Overflows (CSOs). It is a complex system of three tunnels ranging from 8.5 to 18 feet in diameter with a total length of about 2.3 miles that was put into operation in mid-2021. The project lies within and below the cultural, educational, and medical hub of Cleveland, which presented unique design and construction challenges. This paper provides a case history of the design and construction, with particular attention given to lessons learned in devising a large tunnel system that can carry both dry and wet weather flows constructed in rock with limited cover, within a flood plain area and vibrant urban center

Dec 1, 2022

By Philip Morey

Large scale surface coal mining will be required to fill future energy demand in the United States. In realization of this long-term commitment to coal resources, the U.S. Energy Re-search and Development Administration sponsored a study to determine the costs and problems of large-scale surface coal mining. As a result of this study a series of computer models were developed that can be used by government and industry to: 1) facilitate mine design and equipment selection, 2) provide detailed analyses of mining and processing costs. Two types of models were developed: detailed simulation models, which provide detailed information on mining systems and equipment to assist in mine design and equipment selection1 and broad models, which provide a first-order evaluation of deposits and new ventures for an entire mining complex. The complete model series permits examination of surface coal mining under a variety of terrain conditions. Six different mining methods were analyzed and documented during the overall project: 1) Area stripping with draglines, 2) Area stripping with draglines, extended bench, 3) Contour stripping with draglines, 4) Area stripping with shovels (loaders) and trucks, 5) Mountain top removal with shovels (loaders) and trucks, 6) Multiple dipping seam mining with shovels (loaders) and trucks. Each major operation in the coal mining pro-cess is represented in these models so that the best methods and equipment may be selected and 50 that the impact of such selection will be reflected in estimates of capital investment, operating costs, and coal price. Individual models allow the user to separately analyze overburden removal, overburden drilling and blasting, coal drilling and blasting, coal loading and hauling, coal preparation and handling, land reclamation, and premining, facilities, and administrative expenses. Because it is impossible to cover all the models in this paper, only the detailed simulation models representative of the technique "area stripping with draglines," are described. The Fort Union Strippable Coal Resource Region, one of eight test cases, is used as an example to describe the models.

Jan 1, 1978

By David A. Lee

It was estimated in Chemical Week1 that the uranium fuel requirements for the U.S. Electric Utility Industry by the mid 1980's would be about four times that-of what it is today. This corresponds to approximately 45,000 tons per year of 'yellow cake' - of which a good portion is represented by ammonium diuranate - vs. the 11,700 ton total estimated for 1975. Perhaps just as significant is the 40-fold increase in thirty years projected for the entire world since 1970. Thus by the year 2000. 'yellow cake' production could be in the order of [3]50.000 short tons annually.2 'Yellow cake', so named because of its inherently bright yellow color, is a finely divided precipitate that can be formed after the leaching step when refining uranium ores. Feed solids enhancement then occurs to at least 50% by weight using filters or centrifuges This is followed normally by drying and then calcining with the conversion of ammonium diuranate to triuranium octoxide represented by the following equation: [9 (NH4)2 U2 07 heat 14 NH3 7 + 15 H2O7 + 2N2/ + 6 U308 4] Theoretically, assuming 100% conversion every 100 kgs. or 100 lbs. of ammonium diuranate will result in 90 kgs. or 90 lbs. of triuranium octoxide.

Jan 1, 1976

By L. R. Gremillion

Chemical and mineralogical data on 25 apatitic phosphate ores of diverse origins from commercial deposits around the world were widely variable. From 14 to 18 chemical constituents of each sample were determined, and each sample contained 4 to 10 mineral phases. Altogether there were 34 different mineral phases, many of which occurred in only one sample. The samples contained varieties of francolites, fluorapatites, and mixed hydroxyl-fluorapatites. The apatite compositions calculated from the chemical data showed that certain types of substitutions were characteristic of different apatite varieties, but every variety had some degree of substitution of (CO3)2 for (PO4)3 and the P2O5 contents of the apatites ranged from 35.1% for a North Carolina apatite to 41.9% for a Missouri apatite. In a concentrate with a grade of 32% P2O5, the North Carolina sample should contain about 8.7% gangue and the Missouri sample about 23.7% gangue. To optimize the digestion process of a phosphate are, it is necessary to consider the dissolution behavior of the different mineral phases during acidulation and the effects they may have on the chemical properties of a fertilizer intermediate. In the production of wet-process acids or superphosphates, the acidulation of certain minerals may cause foaming and formation of sludge, filtration, corrosion, and handling problems.

Jan 1, 1978

An important problem in mine operations is the classification of material as waste, low-grade stockpile, and ore. This classification must often be made with blasthole data that are widely spaced and that have sampling errors. Geo-statistical simulation techniques combined with basic economic principles allows a procedure for classification that maximizes expected profit. Geostatistical simulation methods (Gaussian, indicator, or annealing-based) allow the integration of hard and soft data in the creation of alternative, equally-probable, realizations of the mineral grade(s). At each location, for each realization, we calculate the "profit" if the block were to be classified as ore or waste The optimal classification is the one that maximizes expected profit (a Maximum Profit Se-lection (MPS) procedure). We discuss the theoretical justification of the method and implementation details. The use of blasthole data from different types of mineral deposits, that is, different levels of continuity, is considered. We also show the efficacy of the procedure with different levels of sampling error. The increased revenue due to the MPS procedure and improved sampling is shown. We show the geostatistical simulation procedure and the uncertainty in block grades that result from incomplete and imperfect sampling. The optimal classification is presented. Optimal block classifications are transferred to realizable dig-limits by hand-drawing polygonal boundaries. We compare the results of the proposed method to classification based on kriging. Limitations and areas of future work are identified.

Jan 1, 1999

By H. O. Harju

Inco acquired majority interest in the nickel laterite concessions in eastern Guatemala in 1960 and, through its subsidiary Exmibal, extensively explored the deposits until 1965 to define the site for project development on the north shore of Lake Izabal. This paper outlines the exploration methods used to evaluate the Guatemalan laterite deposits.

Jan 1, 1979

By Osvaldo A. Bascur

Standards and Technology for bringing information at the desktop has greatly evolved in recent years. The benefits to be realized depend on how these new tools are embraced at the performer level. A key operating challenge is to ensure collective effort is geared towards the most efficient achievement of identified operating and corporate objectives. Presentation, application and data repository modular software are emerging in successful client server applications. The industrial desktop emerges as the new tool for continuous improvement and innovation in industrial operations. Here, process information, reliability maintenance, process simulation, production schedules, performance monitoring are integrated using Microsoft enabling tools at the desktop. A workflow model is presented to assist in implementing a strategic information system in metallurgical plants.

Jan 1, 1996

By K. Kavouridis

The energy and climate protection policy of European Union (EU), and its Member States adopted in 2007 bridges security of supply, environmental protection and competitiveness. The objectives of the EU energy and environmental strategy cover the foreseeable period till 2020. It assumes all sources of energy will be needed. The objectives for renewable and improved efficiency are ambitious; it must be established if they are also realistic. Coal can continue to make valuable contribution to the security of supply and low price of electricity, only with technologies allowing for drastic reduction of the CO2 emitted of its combustion. The aimed at -20% reduction of green-house gases (GHG) of EU-27 by 2020 is an objective limited in time and content. Europe produces less than 15% of global CO2 and this will be reduced to 10% in 2030. Emissions Trading (ET) is to remain the central instrument for CO2 management, especially in the power sector. ET scheme (ETS) or other mechanisms need designing to create an incentive for investment in higher efficiency and technologies and to Carbon Capture & Storage (CCS). The ETS as the climate protection instrument of the EU can become a heavy burden (high fuel and electricity prices, less security of supply) or it can create a climate for modernization of fossil fuel power plants. The suggestion in this paper of fuel-specific benchmark system for CO2 allocation after 2012 can combine the emission levels to be reached with a strong drive to invest, the necessary investment security, transparency and the principle of proportionality. A Benchmark System as recommended by coal industry could adapt to the different circumstances in the long term and comply with EU energy and environmental policy objectives.

Jan 1, 2008

By Martin B. Treuhaft

Expectations for coal in the early to mid-1970's prompted the government and industry to pursue research and development programs to increase underground and surface mining coal productivity and net coal recovery. Several programs concerned advanced surface mining methods for thin seam coal recovery. Three such programs, along with related areas of interest, are presented in this paper, namely: (1) extended depth augering for trench-strip applications; (2) high recovery auger heads for enhanced recovery; and (3) variable wall mining in low cover longwalls. Conceptual development is examined, prototype testing is discussed, and potential operations are considered.

Jan 1, 1983

By F. C. Appleyard

As one of the more important Industrials Minerals, gypsum occupies a significant place in the economy of the United States, particularly in that segment which can be loosely called the Construction Industry. For many years, products made from gypsum have been a major building material, and the usefulness and versatility of these products is such that their widespread use is expected to continue. In 1968, according to U.S. Bureau of Mines statistics, the value of all gypsum products sold in the United States was 405,000,000 - and although this value has dipped from the 1964 high of $ 432,000,000, it is expected to trend upward in the next few years to equal and surpass this figure as the construction industry recovers from its current squeeze of "tight money" and high interest rates. There are many factors to be measured in determining the potential value of any mineral deposit, and how it might fit within its particular industry. What, then, are the qualities which a gypsum deposit must have in order to profitably participate in the four hundred million dollar plus business which is the gypsum industry? First let's consider the geology of gypsum, the geographic distribution of deposits, and the more important factors such as size, grade, capital requirements, and operating cost. Then, an understanding of the uses of gypsum, various types of products, and location of markets would be helpful, along with such other factors as the structure of the industry, price trends, etc.

Jan 1, 1970

By Garry M. Hughes

Lynn lake, Manitoha, where Sherritt has operated a copper-nickel mine since 1954, is located north of the 56th parallel approximately SOO miles north of Winnipeg. Sherritt's new, 3,000 tpd, copper-zinc Fox Mine is situated 30 miles southwest of Lynn lake. This paper focuses on the Fox Mine concentrator, hut first some background information. Sherritt Gordon Mines Limited started mining operations as a copper-zinc producer in 1931 at Sherridon, Manitoba, 150 miles south of Lynn Lake. As Sherridon fizzled out development of a series of nickel-copper orebodies commenced at Lynn Lake. The Forward process was developed to treat the nickel concentrate from the Lynn concentrator. Sherritt's ammonia leaching process is now history and is expected to gain more prominence as pressure is applied to the mining industry for closer environmental control. But few are aware of the fact that the present Lynn Lake crushing plant and concentrator were dismantled in the autumn of 1951 and freighted from Sherridon by tractor train during the winters of 1952 and 1953. The copper-zinc orehody at Fox Mine was discovered early in 1961 by geophysical methods which included both airborne and ground surveys. It is part of a ,large body of massive and semi-massive sulphides consisting chiefly of pyrite; with chalcopyrite, sphalerite (containing 7-9% iron) and pyrrhotite in varying proportions which occur within a series of volcanic and sedimentary rocks. The total mineralized zone is a lenticular body with a minimum average length and width of 1,350 feet and 66 feet respectively, to the explored depth of 2,000 feet. The average sulphide content is 67%. Higher zinc zones are masses of pyrite grains cemented by sphalerite with lower than average copper content. Zones higher in copper and lower in zinc are slightly more quartzose. Gold and silver are present in small amounts roughly proportional to the copper content.

Jan 1, 1971

By Enrico Pavese, Tim Kearney, Stefan Lemke

Watertightness is of central importance in hydraulic and underground structures but has always been associated with a risk, as demonstrated by the very high impact that water inflows have on the damage of linings and infrastructure (Howard, 1991; Sandrone and Labiouse, 2011). Concrete is vulnerable to groundwater and chemical contaminants in the soil. These can leach into the pores and cracks of the concrete and degrade its integrity, causing spalling and corroding the reinforcing steel. Moisture migrating into the building can also degrade structural elements over time and lead to mold and other hazards to occupants’ health. In this connection, the demands placed on the setup and detailed design of the seal depending on the negative influence by water on the one hand and on the other hand on the function of a construction in view to its watertightness classification. Thus, the reliable functioning of a seal is of particular significance in the case of traffic tunnels, which are not easily accessible for all subsequent repairs after the construction in seepage water and especially when located in a pressure water zone (risk–cost assessment). Requirements for the long-term efficiency and quality of underground structures have increased in recent decades. Today, the standard lifetime requirement for an underground infrastructure project is 100 to 120 years and, in some cases, even higher. This calls for high increased attention to the durability of the whole structure and of each individual element. Standards, which started as application guidelines given by the manufacturers, are available in the market since the 1980s and are constantly adapted to the current developments in various technical committees. Differentiations are made between: Manufactures application guidelines, case studies or published articles Test standards for the laboratory to guideline the testing procedures (air temperature, type of test equipment, dimensions, test speed, test duration, concentration, type of liquids, monitoring, tolerances, interpretation of results, documentation, etc.), developed by committees based on material and laboratory experts Application standards, which include test standards but also the related minimum performance requirements (values) for material, processing, and quality assurance (practical tolerances), developed by committees based on a wide range of experts (e.g., designers, construction companies, applicators, manufactures, owners, test institutes, quality engineers) and therefore also based on a wide field of experience, different views and up-dated case studies. In the following there are some examples of guidelines and published information’s, ranked according to the year of issue, which are relevant for the development of waterproofing specifications in the tunnel industry:

Jun 13, 2023

By R. A. Pimentel

Many longwall operators experience difficulty complying with the federal regulation limiting average dust exposure. Others are currently in compliance, but the dust exposure limit keeps then from increasing their production. Spray water is a major means of dust control. Excess water can cause problems in the transportation system and the cleaning plant, and reduces the Btu value of the run of mine coal. Thus, the dust exposure reduction per unit of water sprayed must be maximized. This paper discusses underground tests recently completed as part of a Bureau of Mines research program to determine the effects of variations in spray water flow rate, pressure, proportioning and spray orientation on longwall shearers.

Jan 1, 1984

By A. P. Schissler, S. Badr, U. Ozbay, M. D. G. Salamon

Yield pillars are used in deep coal longwall mines, where the depth of cover is so great that a conventional chain pillar design tends to be unsuccessful. The design of yield pillars in deep U.S. mines has been based mainly on experience, pressure arch theories, numerical modeling, and empirical methods that originated in the eastern U.S. coal mines. This paper offers field experience based guidelines for the design of yield pillars through analysis and evaluation of numerous case histories. Case histories of yield pillar applications were collated and critically reviewed to identify trends in data that can be used to formulate the design guidelines. Convincing trends observed in the case of successful case histories indicate that yield pillars should have a width to height ratio in the range from 2.8 to 6.0, a stability factor during development between 0.4 and 0.6, and shed between 94% to 98% of the cover and abutment load, as provided by the Carr-Wilson (1982) method. Also, yield pillars should be utilized in coalmines only where the roof and floor rock have a CMRR rating of 50 or better.

Jan 1, 2003

By B. Pesic

Northwest Alloys, a wholly owned subsidiary of Alcoa, produces magnesium from dolomite by reduction with ferro silicon and aluminum. This process produces alkaline by-products in quantities that allow their consideration for use as commercial by-products. Two such products are dicalcium silicate slag, Di-Cal, and magnesium oxide condensate, MgO. The alkaline properties of these materials offer acid neutralizing capability comparable to the traditionally used lime, therefore, warranting a study for their use in applications where the neutralization of acidic waters or process solutions is required, such as treatment of mine waters. In this ongoing study, three mine waters (Bunker Hill Mine, Berkeley Pit, and Blackbird Mine) were selected for treatment with Di-Cal and MgO. Lime was used as the background control. The solid precipitates were subsequently contacted with pure water at four different pH conditions for stability testing of prepared metal precipitates (expanded TCLP). It was found that neutralization with Di-Cal results in precipitates which are of equivalent to superior stability than those from lime treatment.

Jan 1, 1999

By Gamal Rashed, Zorica Radakovic-Guzina, Khaled Mohamed

"Underground coal mines use mechanical bolts in addition to other types of bolts to control the rib deformation and to stabilize the yielded coal ribs. Limited research has been conducted to understand the performance of the mechanical bolts in coal ribs. Researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted this work to understand the loading characteristics of mechanical bolts (stiffness and capacity) installed in coal ribs at five underground coal mines. Standard pull-out tests were performed in this study to define the loading characteristics of mechanical rib bolts. Different installation torques were applied to the tested bolts based on the strength of the coal seam. A typical tri-linear load-deformation response for mechanical bolts was obtained from these tests. It was found that the anchorage capacity depends mainly on the coal strength. Guidelines for modeling mechanical bolts have been developed using the tri-linear load-deformation response. The outcome of this research provides essential data for rib support design.INTRODUCTIONThe design of rib bolting in U.S. coal mines is based on a trial-and-error process, which is insufficient to eliminate injuries and fatalities caused by rib falls. In the last 10 years, rib failures have resulted in 17 fatalities, representing 52% of the ground-fall fatalities in underground coal mines in the United States (MSHA, 2018). Recently, NIOSH researchers surveyed 90 sites in 14 underground coal mines in the Eastern United States and found that 11 mines are bolting coal ribs, with 4 of those mines using the conventional mechanical bolts and the others using fully-grouted bolts. NIOSH researchers are developing an engineering design procedure for rib support. Pull-out test programs for mechanical and grouted rib bolts were conducted to understand the rib control mechanisms of rib bolts. Only the test results of mechanical bolts are presented in this paper.Mechanical bolt (or point-anchored bolt) is a tensioned bolt anchored down the borehole with a mechanical expansion shell or a resin-grouted medium (Peng and Tang, 1984). The mechanical anchor bolt consists of a plug, a shell anchor, a headed bar with the top end threaded, a bearing plate, a hardened washer, and occasionally a friction-reducing washer. The shell anchor can be either standard or bail type (Figure 1). The standard type shell is held in place by a nut, while the bail anchor uses a strap to hold the shell in place (Peng, 2008). The diameter of the bar is generally 16 mm (? in) for the #5 bolt or 19 mm (6/8 in) for the #6 bolt. The diameter of the hole that the bolt is inserted into must be carefully controlled, since an oversized hole can result in poor anchorage (Moss, 1971). The anchorage is obtained by applying torque to the bolt head, which in turn pulls the plug down in the shell and expands the serrated leaves against the sides of the hole-wall. In the resin-grouted anchor, the resin replaces the mechanical expansion shell at the end of the hole. The anchorage is achieved by bonding between the resin, bolt, and the hole-wall."

Jan 1, 2019

By R. J. Roman

The results of column leaching tests on 3 different mixed oxide/sulfide ores from a Chilean deposit are presented. The 3 samples contained different ratios of oxide copper minerals to chalcocite and chalcopyrite. The results of the column leach tests are interpreted in light of the shrinking core model for coarse particle leaching. The copper recovery from the oxide minerals and the sulfide minerals each conforms to the shrinking core model with the total recovery equal to the weighted average of the individual minerals. The use of column test results to predict field heap leaching results using the multi-mineral shrinking core model is discussed.

Jan 1, 1993

By Z. Hyder, M. D. Cleason

"INTRODUCTION Mine Ventilation has come a long way over the years. The main purpose of mine ventilation is to keep conditions in the mine safe for the worker so that the mine will be productive and profitable. Technological developments to the mine ventilation system itself and the development of mining techniques have helped improve the safety and productivity of the miners and the mine. Most of the developments to mine ventilation and to safety devices came as the result of serious mining disasters. Another effect of those mining disasters, especially in the late 19th century and after, was legislation to set specific safety standards for mines, especially in the underground coal mines. This paper will focus on the connection between mines disasters and the mine safety legislations promulgated because of those disasters. A BRIEF HISTORY OF MINE SAFETY LEGISLATION Mine legislation has a long history in the U.S. dating back well in the 1800’s. However, mine safety legislation is considerably newer. In 1891, the U.S. Congress passed the very first version of mine safety legislations setting up minimum safety standards. By today’s standards, the 1891 legislation was incredibly basic (7). It took a series of horrific mining disasters for Congress to take action a second time. In 1910, Congress established the Bureau of mines. The role of Bureau developed and changed over next 60 years. In 1995, Congress voted to disband it (27). Initially the Bureau was only charged with investigating and coming up with ways to reduce accidents in coal mines. It was not until 1941, when Congress formally allowed Bureau of Mines’ Inspectors into the mines. In 1947, the Congress enacted and adopted a set of federal safety regulations for the inspectors to follow (1). Finally, in 1952 Congress granted the Bureau of Mines the authority to inspect the mines and to issue citations and/or orders of withdrawals. This act was known as the 1952 Coal Act and the penalties were limited to civil penalties. It would take a couple more iterations of mine safety legislation for monetary and criminal penalties to be introduced (10). Up until 1966, mine safety legislation was directed primarily at underground coal mines and surface coal mines. Congress passed the Federal Metal and Nonmetallic Mine Safety Act of 1966, thus providing a set of standards for all mines to follow (1). The 1952 Coal Act was amended again to be the Federal Coal Mine Health and Safety Act of 1969. This amendment was the beginning of modern mine safety legislation (13). In 1973, Congress created what can be considered the first ‘version’ of the modern day MSHA (Mine Safety and Health Administration). The initial version was the Mining Enforcement and Safety Administrations or MESA. Congress created MESA to act as the enforcement agency, relieving the Bureau of Mines of that responsibility so they could focus on their initial purpose, the development of countries natural resources (14). As mining industry grew, mine safety and health became a greater concern and priority. More efforts were put in legislating the industry. The Federal Mine Safety and Health Act of 1977 provided the platform for today’s mine safety and health legislation. Under the Federal Mine Safety and Health Act of 1977, also known as the Mine Act, MSHA came into being (1)."

Jan 1, 2016

By Shani Engelbrecht, Belinda McFadzean, Avuyile Wali, Natalie Shackleton, Vratislav Malysiak

Frothers play a crucial role in sulphide and PGM ore flotation recovery, and AECI Mining Chemicals studies on PGM ores have shown significant flotation kinetic increases with the optimal frother-collector combinations. Using Senfroth 200 as the industry baseline, remarkable kinetic increases were observed with AECI Mining Chemicals developed frothers in the first concentrate. Even in the worst-case scenarios, 4E PGM recovery increased by 5% at a slightly higher concentrate grade. It is important not to limit frother dosage to a fixed value. Instead, enough frother should be added to maintain a stable bench float, measuring the dosages by frother volume before and after tests. Frothers can be specialized blends and their importance should not be underestimated. The results produced by formulating and innovating frothers to address specific industry challenges have been encouraging. Testing a frother on a plant scale does not have to be as daunting as with collectors, enabling the identification of the best frother-collector combinations at an industrial scale. AECI Mining Chemicals bench scale testwork has motivated plant-scale trials that have successfully transitioned to commercialization. This paper compares the results from metallurgical and froth stability tests and shows that occasionally frothers that have a less stable froth can have improved valuable mineral recoveries, while still exhibiting better drainage for reduced entrainment and mass pull. It was shown that caution should be used when relying only on simplified froth stability tests in the evaluation of new frothers.

Feb 1, 2025