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By H. Habenicht

Requirements for full extraction in underground coal mining call for inexpensive, safe, techniques to be competitive with conventional methods. Longwall and shortwall systems are to some extent employed for this purpose. Another method would be rib pillar extraction (and pillar extraction). These methods are compared with each other with respect to procedure, equipment, safety, roof control, investment, output, performance, costs The advantages of r.p.e. show this method very attractive. Number and cost of equipment are lowest. Safety and roof control becomes improved by a mobile roof support recently developed in Austria. Its successful use in the R.S.A. is being explained.

Jan 1, 1986

By Kexin Cai, Isidro Rivera, Shawna Von Stockhausen, Maria Chastka, Kevin Huynh

The Newell Creek Dam Inlet/Outlet Replacement Project is located approximately 11 miles north of Santa Cruz, California along Highway 9 in the San Lorenzo Valley. This project will replace the existing inlet/outlet works at the Loch Lomond Reservoir by constructing a tunnel using conventional excavation methods while simultaneously drilling three intake shafts to intercept the tunnel from within the city’s water supply. This project will improve the system’s overall operational efficiency and performance, and provide a safe and reliable facility for the City of Santa Cruz’s drinking water supply. This paper discusses the overall project configuration, construction observations, and challenges during construction, including tunnel excavating through the marine sedimentary siltstone of the Monterey Formation, probing and pre-excavation grouting, and the tools utilized to manage the project.

Dec 1, 2022

It has been reported previously that dolomite samples from different locations showed varying flocculation behavior with Poly(ethyleneoxide) (PEO). In this study it is determined that palygorskite associated with the Florida dolomite samples is responsible for their flocculation with PEO. A detailed characterization of the dolomite samples from different locations and its relevance to flocculation with PEO is discussed.

Jan 1, 1994

By G. A. Gruber

A flotation process has been developed to successfully treat ore from the Santo Domingo phosphate deposit in Baja California Sur. The ore contained less than four percent P205 with quartz, silicates, and carbonates as gangue minerals. Flotation of the low grade feed In sea water required that the conventioinal Crago Process, comprising direct anionic flotation, deolling, and inverse cationic flotation be augmented by an anionic cleaner flotation step, phosphate depression, and a calcite flotation step.

Jan 1, 1986

By K. F. Unrug

An overview of the history of mining technology, both past and present, shows that some of the new concepts being successfully applied have changed the reserve categorization and are having an overall impact on production. Past coal mining operations in the eastern coal fields, and especially in Appalachia, extensively utilized stripping with the predominately applied contour method. As a result, vast mountainous areas have abandoned benches left behind by past mining operations. While thicker seams previously stripped were usually mined by underground or mountain top removal methods, thin seams beyond technical or economical limits were left intact after contour mining had reached the ultimate height of the wall. These thin seams quite often contain high BTU, low ash and sulfur coal that makes them attractive for a secondary recovery due to the market requirements. Secondary highwall recovery has obvious potential and is economically attractive; however, with the present state of industrial experience and lack of analysis of site data, a trial and error approach is used by operators.

Jan 1, 1983

By Andrew C. Katen

The mining industry faces increasing geopolitical risk in the coming decades. Constraints such as resource nationalism, corruption and social license could grow to outweigh fundamental limitations like geology or supply and demand (Ernst & Young, 2013; Verrastro et al. 2010). Lurking beneath these more immediate and palpable concerns, however, may be more significant risks entrenched in geography and history. Deep-rooted cultural and strategic forces that emerge slowly ? or erupt suddenly and unexpectedly ? can generate momentous and far-reaching political, social and economic changes. While multinational enterprises routinely assess for political risk, the nature of minerals extraction means long-term and systemic geopolitical conditions are especially important for mining companies to identify and understand. Mine development is a decades-long process that binds companies to the land and makes changing course to avert emerging threats a difficult and costly option. Consequently, geopolitical assessment is a pertinent and valuable tool that mining companies can use to more comprehensively evaluate strategic threats and opportunities. Geopolitics is the study of society, politics and strategy through the lens of geography (Gray, 1996). Its emphasis on relatively permanent physical features of the earth makes geopolitics a uniquely valuable tool for assessing political risk. Topography, climate and natural resources have shaped, constrained and motivated peoples and governments throughout history. These influences transcend regimes, policies and borders ? and even states themselves ? which, by contrast, change often and dramatically. Framing politics against mountains, deserts and rivers supports identification of historical patterns and forecasts of emerging trends. In other words, the physical map provides an objective and consistent model for studying a subjective and dynamic subject such as politics (Sloan and Gray, 1999). Consequently, geopolitical assessment can highlight threats and opportunities that go unaddressed by other risk methodologies that emphasize current conditions (Glancy, 2012). Taken together, the permanence of geography, hindsight afforded by centuries of political history, and interconnectedness of world events makes geopolitical assessment a valuable approach for conceptualizing strategic risk.

Mar 1, 2014

By N. Careddu

In recent years, slabs with a rough surface have captured a large share of the ornamental stone market. However, the main technologies used for this type of treatment are based on mechanical shock (bush-hammering) or thermal treatment (flaming or flame-finishing). These traditional technologies are widely used, but have many limitations that decrease their usefulness. The purpose of this study was to develop a technology that enhances the natural colors of the rock and produces a rough surface without compromising its mechanical characteristics, in contrast to traditional technologies. This report shows the technical, economic and aesthetic results obtained with a new water-jet treatment and compares it with competing technologies.

Jul 1, 2010

Several major impediments threaten the successful delivery of tunnel and under-ground construction projects. In addition to technical design and construction risks associated with tunnel projects, many of which are well understood, budgetary pressures, funding constraints and the complexity of procuring, administering and executing multiple concur-rent projects in a large program could also have a catastrophic impact on the program?s objectives. Contributing factors often include poorly managed design, procurement, construction, managerial, organizational, market and stake-holder risks, as well as nonconforming inputs or outputs to the costs and schedule, or any other potential inabilities to deliver the required or desired results. A strategy to prevent ?failure? of a project requires a proactive and holistic approach to risk management. Through planning, identification, analysis, management, monitoring and control of the project?s risks (both threats and opportunities), attention to management of risk will in-crease the probability and impact of positive events and decrease the probability and impact of events adverse to a project?s objectives.

By C. W. Baxter

Eveleth taconite company was formed in 1963 to mine and beneficiate taconite on the Mesabi range of Minnesota. Its thunderbird mine is located midway between the cities of Eveleth and Virginia, Minnesota, and the crude ore is transported by rail to its Fairlane plant approximately ten miles to the south of the mine, "figure 1". As is implied by the names of the mine and plant, the ford motor company is the principal owner of Eveleth taconite company, with an 85% interest, Oglebay Norton company holds the remaining 15% interest and also is the managing agent.

Jan 1, 1972

By Mahmut Altiner

In the present study, the use of horse residue as an alternative reducing agent in the roasting of a low-grade goethite ore containing 17.60% Fe was investigated. Additional roasting experiments were carried out with corn starch and without reducing agent for comparison. Each roasted product was characterized using X-ray diffraction (XRD) and magnetic hysteresis (MH) loops analyses. The optimum roasting conditions (roasting temperature [400, 500, and 600 °C], reducing agent/ore ratio [0.04, 0.08, and 0.12], and roasting time [10, 20, and 30 min]) were investigated based on the Taguchi approach. The magnetic susceptibilities of the roasted sample with the addition of reducing agents were higher compared to that of the roasted sample in the absence of reducing agent. Experimental findings indicate that the horse residue can be used as the reducing agent. Finally, an iron ore concentrate assaying a Fe grade of 62.12% with a recovery of 56.93% was prepared using wet magnetic separation at a magnetic intensity of 0.5 T from the ore roasted under the following roasting conditions: roasting temperature of 500 °C, reducing agent/ sample ratio of 0.08, and roasting time of 30 min.

Jun 3, 2020

By J. S. Hall

The performance of a full-scale balling drum circuit is well known to fluctuate, and is difficult to control. The fluctuations stem from causes that are not readily quantifiable. Results from plant tests show that surging of the recycle tonnage is dependent, inter alia, on the method of bentonite addition, small variations in drum or cutter bar speed and the method of drum water addition. This paper presents detailed observations from experiments on full-scale drum circuits, including preliminary results of a computer measurement and control scheme. Size distributions measured at points along an industrial drum are presented, together with the results of a mathematical model fitted to one plant data set. Model predictions are also included emphasizing the importance of screen performance on circuit stability.

Jan 1, 1983

By R. M. Rowe, T. E. Irwin

A flowsheet was developed for upgrading Climax tin concentrate to about 45 percent Sn. Bench-scale test work conducted at AMAX Extractive Research and Development, Inc., was used to design a multiple-stage tin- processing flowsheet which included screening, high-intensity magnetic separation, and high- tension (electric- static) separation. Formal engineering and plant installation was accomplished in-house by Climax mill personnel. The successful start-up operation of the facility was the joint effort of the AMAX R&D and Climax-mill staffs.

Jan 1, 1986

By D. L. Boreck

With increasing land development, the potential of fatalities from abandoned mine shafts increases. To minimize potential liability, shaft closure should be a critical part of mined land reclamation. The Bureau of Mines is conducting research into using lightweight foam concrete in sealing abandoned coal mine shafts. A demonstration seal consisted of a 3m thick foam concrete plug to provide lateral stability inside the shaft. A high density concrete cap provided load-bearing capacity for a 100-year service life. The USBM has also completed research into changes in foam concrete when it is pumped or dropped from different heights. It is concluded from the research that foam concrete can undergo significant air loss with pumping or dropping. This foretells significant changes in the characteristics of the concrete as well as an increase in the weight and cost of the in-place concrete seal. When using foam concrete to seal abandoned mine shafts, care must be taken to minimize air loss during placement.

Jan 1, 1994

By Grant Davis

An International Symposium on the Ecology and Revegetation of Drastically Disturbed Areas was held at the Pennsylvania State University in August 1969. Scientists from 13 foreign countries and 18 states in the United States attended this meeting, which focused on those areas disturbed by mining. The symposium enabled scientists from all over the world to get together for two weeks and discuss informally some of the knotty problems of reclaiming these disturbed areas. Trying to present the results of each of the 64 papers delivered at the symposium might be difficult. So, I will try to bring you up to date on the general status of research on the reclamation of surface-mined areas, particularly in revegetation and hydrology. I will also mention some research that is under way but was not presented at the symposium.

Jan 1, 1970

Heap leaching has become one of the prime technologies used for the recovery of precious metals from low-grade ores over the past ten years. The recovery process involves mining and stacking the ore on engineered leach pads, with or without crushing and/or agglomeration, followed by leaching with a low concentration sodium cyanide solution. The metal-bearing, pregnant solution is then processed by zinc precipitation or activated carbon absorption to extract the precious metals. The leaching process continues until all economic metal values are removed at which time the spent heap leach pads, the leached materials and excess process solutions require decommissioning. The management of these solutions may present a potential challenge for successful and environmentally sound decommissioning due to their composition, volume or continuity of generation from the spent ore even though active leaching has been terminated. The principal objectives of solution management in decommissioning spent heap leach pads are to meet all operative environmental regulations in a cost-effective manner and to leave the pads in a condition where they do not present a long-term liability either to the operator or to the environment. This involves the reduction in volume of the residual process solutions and/or treatment of these solutions to where they meet applicable water quality criteria. In the past, the environmental and economic aspects of decommissioning and solution management have been overlooked or under-estimated during the planning of mining operations. As a result, there is a potential for long-term liabilities and costs to be recognized only at the end of active leaching, a time at which operating revenues and cash-flow are minimal. Therefore, the decommissioning process requires addressing at the mine planning stage and agencies now require that a plan for solution management after the cessation of operations be submitted prior to initiation of mining. This paper discusses aspects of process solution management during decommissioning, both in terms of quantity and quality, and how potential issues may be recognized and planned for in the initial stages of heap leach design.

Jan 1, 1992

By V. P. Mehrotra

The effect of dissolved ions present in plant water on the flotation of phosphate ore from central Florida was investigated. Of the three most abundant ions, namely Ca++, Mg++ and SO4--, calcium ions were the most detrimental in the flotation of phosphate with sodium oleate collector. In one feed, a 10 ppm concentration of Ca++ ions reduced the BPL recovery from 86% to 46% whereas in the other a 40 ppm concentration lowered the recovery from 90% to 52%. The effect of Na2C03, NaHC03, Zeolite and EDTA to remove ca++ ions from water and hence improve apatite flotation was also studied.

Jan 1, 1986

By F. H. Mertens

The costs of an open-pit operation can be classified according to the following hierarchy : -overall cost of production (per ton of ore) -costs of basic operations and functions -costs of auxiliary operations -costs of machines and equipment -maintenance costs. Production cost is a measure of the open-pit mine performance and should be the final target of the management control. It is also a measure of the share of the mine in the processing stages.

Jan 1, 1990

By John M. Smith

Kaolin is an important industrial mineral because of its unique properties and low cost. Strictly defined, kaolin is the name given to a group of hydrous aluminum silicates of which kaolinite is the most common mineral (1). Through common usage the mineral, kaolinite, is called "kaolin" or "china clay". In 1972 over 4, 000, 000 tons of kaolin will be beneficiated and shipped by domestic producers. By far the largest user of kaolin is the paper industry which utilizes approximately 65 to 70 per cent of the total production. Kaolin is used in paper as a filler in the interstices of the sheet and as a coating to impart smoothness, gloss, brightness, and printability to the paper. The rubber industry is also a large user of kaolin where it is used as a filler because it adds strength, abrasion resistance, and rigidity to both natural and synthetic rubber goods. Kaolin is used as an extender in paints because it is chemically inert, has a high covering power, gives desirable flow properties, and is low in cost. In ceramics, kaolin is used in whitewares, tile, insulators, refractories, and in some face brick where a white color is desired. Kaolin is also used extensively in plastics as a filler in thermosetting and thermoplastic mixes to give smoother surfaces, a more attractive finish, good dimensional stability, and resistance to chemical attack. Many other process industries use kaolin as a filler, suspending medium, or for color improvement.

Jan 1, 1972

By Charles J. Johnson

The United States is totally dependent on imports for all primary chromite and most ferrochrome supplies. Although the United States imports chromite and ferrochrome from a number of countries, the long-term future of chromite supplies appears to lie in southern Africa (Republic of South Africa and Zimbabwe) where 88 percent of known world reserves exist. Floreover, low mining costs and the availability of low-cost electricity for ferrochrome production gives South Africa a comparative advantage over most other chromite and ferrochrome-producing nations. A well-known problem faced by the United States is that when viewed from a longer-term perspective, the major sources of supply of metallurgical grade chromite and ferrochrome may be subject to disruption. The three countries that have caused the greatest concern have been the Republic of South Africa, the Soviet Union, and Zimbabwe. South Africa presents a particularly difficult problem because it may be subject to internal political unrest and/or U. N, economic sanctions. South Africa has increased its share of world chromium production from about 30 percent in 1968 to 62 percent in 1978.1

Jan 1, 1982

By R. Wisniewski

Every underground coal mine in the United States must deploy and operate a wireless communication and tracking system. This paper addresses the reliability and availability of an installed tracking system and the communications infrastructure that supports it. A particular interest is the requirements for the systems to operate continuously without failure after a mine disaster for 96 hours, and the requirements in the MINER Act for the tracking systems to be ?calculated to be serviceable? and the communications systems ?redundancy?. These requirements imply a certain reliability and availability. This paper describes a quantitative way to assess these systems requirements, using the tools that are available and commonly used by the Reliability, Maintainability, & Availability community.

Feb 23, 2014