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By S. A. Smith-Hamm, E. A. Sarver, A. S. Cox

Appalachia is an increasing concern, as unnaturally high TDS and/or associated specific conductivity (SC) may contribute to deteriorated stream ecosystem health. The aim of this preliminary study was to explore the efficacy of accelerated leaching as a means of minimizing long-term TDS/SC generation by problematic overburden materials. Five spoil samples were collected and leached using simulated rainwater solutions under ambient and acidified pH conditions. SC and pH were monitored during each leach cycle, and inductively coupled plasma-mass spectroscopy (ICP-MS) was used to determine how leaching conditions affected the release of specific ions. This paper highlights the results of both jar and column leaching tests. Among the most significant findings was that for certain spoil materials, the SC in the leach column effluent was effectively reduced when the spoil was first leached with acidic rainwater followed by ambient rainwater, as opposed to leaching with ambient rainwater alone. This suggests that accelerated leaching might aid in the long-term stabilization of some materials.

Jan 1, 2015

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 N. A. Karl, D. R. Wilburn

"This summary of international mineral exploration activities during 2017 draws upon information from industry sources, published literature, SNL Metals & Mining (SNL), an offering of S&P Global Market Intelligence (New York, NY) and specialists in the U.S. Geological Survey (USGS) National Minerals Information Center. Three types of information are reported and analyzed in this annual review of international exploration: 1) budgetary statistics expressed in U.S. dollars provided by SNL; 2) regional and site-specific exploration activities that took place in 2017 as compiled by the USGS and 3) regional events and legislation that affected exploration activities including economic, social and political conditions, which were derived from published sources and discussions with USGS and industry specialists. Commodity and regional compilations are presented in this summary. Because multiple sources were used to develop commodity and regional compilations, statistics may vary depending on the source and type of data that are being reported.The SNL data summarize budget estimates for worldwide exploration activities in 2017 for 30 nonfuel mineral commodities and metal alloys, based on company surveys. Surveys focused on precious metals (gold, platinumgroup metals (PGMs) and silver), base metals (cobalt, copper, lead, molybdenum, nickel, tin and zinc), bulk commodities (bauxite, chromite, iron ore, manganese, phosphate and potash), and other commodities (aluminum, antimony, diamond, graphite, heavy-mineral sands, lithium, niobium, rare-earth elements (REEs), scandium, tantalum, tungsten, uranium, vanadium and yttrium). Information on uranium exploration activities was included in SNL’s survey for the first time in 2007. Data on lithium, niobium, phosphate, potash, REE and tungsten were compiled for the first time in 2010, and scandium, vanadium and yttrium were added in 2014 because of their increased topical significance. Since 1999, companies with exploration budgets of $100,000 and greater were included in the SNL surveys. SNL budget estimates exclude coal, and oil and gas. The 2017 SNL mining company survey compilation was reported by SNL to include an estimated 95 percent of the world’s nonfuel mineral exploration budgets. The 5 percent that was not covered was accounted for by companies that chose not to participate in the SNL survey, private companies that do not publish their budget data, and government-funded exploration activities."

Jan 5, 2018

By Xun Luo, Yi Duan

A field trial of by distributed optical fiber sensing (DOFS) technique was conducted at a longwall coal mine in Australia. This investigation was designed to assess the applicability of DOFS for microseismic monitoring in mining. The experiments used commercially available optic fiber cables, geophones and associated data acquisition instruments – a fiber interrogator and a seismic recorder. The fiber cable was deployed in a 300m deep hole and in trenches of approximately 3.5 km long on the ground surface around and across the longwall panel being mined. The results obtained from the experiments have shown that DOFS is able to acquire microseismic data with quality that is comparable to geophones. It has been proven that DOFS can achieve higher spatial resolution for seismicity sensing and higher accuracy for locating events than a geophone network. These characteristics are particularly useful for using DOFS to monitor ground vibrations associated with ground caving processes and rock fracturing events induced by mining and civil engineering. It was also found that far more additional seismic events were recorded by the fibers than by the geophones. Automated data discrimination and processing methods must be developed in order to utilize DOFS for real-time applications.

Apr 26, 2022

By B. Eiter, M. Barham, T. Bauerle

Fatigue-related risk is a persistent safety concern for the mining industry. However, fatigue and sleepiness are often treated interchangeably, which can lead to confusion and potentially less effective reduction of safety risk. To provide clarity, we present an overview of similarities and differences between work-related fatigue risk and sleepiness including definitions, theories, measurements, and mitigation strategies. As a supplement, a summative visual model which highlights these similarities and differences is presented. Expanding industry knowledge in this area will assist safety professionals in crafting more targeted risk management practices appropriate for work-related fatigue risk, sleepiness, or both.

Feb 1, 2023

By D. D. Harbuck

The U.S. Bureau of Mines investigated germanium and gallium extraction from an ore containing 0.089% Ge and 0.036% Ga. While previous researchers concluded that a reducing agent such as 502 is needed to extract germanium and gallium from such ore, this research showed that high extractions (87% Ge, 97% Ga) were possible using sulfuric acid alone, if the acid concentration were properly controlled. This control was achieved using a two-stage counter-current leach circuit. Microprobe analyses revealed that the non-extracted germanium is in solid solution with quartz, and therefore cannot be leached with 502 or sulfuric acid.

Jan 1, 1991

By Ralph M. Foecking

The disposal of the phosphate slimes produced by Florida beneficiation operations is perhaps the biggest single problem of the phosphate mining industry. This is an old problem which has not been solved and which is becoming increasingly severe. In a typical phosphate mining operation, the phosphate rock mined is initmately mixed with sand and clay, constituting what is known as matrix. During the beneficiation, the clay and other fine materials are separated usually at -150 mesh, and washed from the phosphate rock in a form of diluted slurry known as phosphate slimes. The quantity of slimes solids and their composition vary considerably with the location but usually represent from 25 to 35% of the ore mined. Because of the affinity that clays have for water, large volumes of water are required to separate the granular material in the matrix forming a dilute slime suspension (1.5 to 3% solids) of colloidal material, which settles very slowly, and thus requires immense impounding areas, which never becomes totally usable land. These ponds also contain about 25 to 35% of the total P205 values mined. The magnitude of the problem represented by the slimes can be appreciated better if we realize that there are around

Jan 1, 1971

By H. A. Kortmann

For the commercial production of iron ore pellets from hematite ores, as it is practiced in various pellet plants, the addition of lime has shown to be an efficient means with a view to improving cold compression and abrasive strength of the indurated pellets considerably. Unfortunately, it has also been shown at the same time, that the metallurgical properties as, for instance, swelling behavior, softening during reduction under load and disintegration of the grain, can be adversely affected to a high degree. In the course of smelting tests carried out by renowned steelworks, blast furnace operation was heavily disturbed by the swelling and early softening of the pellets, also by their disintegration in the low-temperature range, which altogether led to a considerable lowering of the smelting rate (1, 2, 3).

Jan 1, 1972

By A. D. Trujillo, R. D. Wunder

The Chino Mines Co., a Kennecott- Mitsubishi partnership, located in Hurley, NM, recently completed a $405 million modernization of its mine, concentrator, and smelter facilities. The mine/concentrator modernization commenced in 1980, and the smelter modernization began during 1982. Modernization of the mine and concentrator facilities involved increasing the mining rate from 98 kt/d (108,000 stpd) to 152.2 kt/d (167,800 stpd). Ore mining was designed to increase production from 20.2 kt/d (22,300 stpd) to 34 kt/d (37,500 stpd). A new concentrator was con- structed near the mine using semiautogenous grinding. The new smelter uses the INCO flash smelting process, increasing capacity by 40.8 kt/a (45,000 stpy) to 99.8 kt/a (110,000 stpy) of saleable copper.

Jan 1, 1988

By C. A. Rowland

When studying the feasibility of using autogenous or semi-autogenous grinding, operating and engineering companies frequently request assistance from the mill manufacturers in three areas - 1. Recommendations for studying the suitability of autogenous or semi-autogenous grinding for the specific ore. 2. Mill sizing, to accomplish required grind. 3. Recommendations on mill design and operation. Rod mills and ball mills are selected by the use of bench scale standard grindability tests and established calculation procedures, of which the most frequently used are the Bond Grindability tests and the Bond Work Index equation(1). The accuracy of these have been reviewed by C. A. Rowland in his papers, showing the correlation of work indices calculated from plant operating data and laboratory grindability tests(2)(3). The selection of autogenous and semi-autogenous primary mills has not reached the stage where mill size selection can be made from bench scale tests. Considerably more extensive testing will be necessary than required for selecting rod mills and ball mills.

Jan 1, 1974

By Staff

In 2012, the estimated value of mineral production increased in the United States for the third consecutive year. Production and prices increased for most industrial mineral commodities mined in the United States. While production for most metals remained relatively unchanged, with the notable exception of gold, the prices for most metals declined. Minerals remained fundamental to the U.S. economy, contributing to the real gross domestic product (GDP) at several levels, including mining, processing and manufacturing finished products. Minerals? contribution to the GDP increased for the second consecutive year. Trends in other sectors of the domestic economy were similar to those in mineral production and consumption rates (Table 1). After continued decline following the 2008-2009 recession, the construction industry began to show signs of improvement late in 2011 and throughout 2012, with increased production and consumption of cement, construction sand and gravel, crushed stone and gypsum, mineral commodities that are used almost exclusively in construction.

May 1, 2013

By ZHONGLING ZHAO, WANTING SONG, GUOZHONG LIU, LEIXIN SHI, ZUI WANG, YUANYUAN LIU, KE GAO, DONGHONG JIANG, WANG LUO, PEICHAO LU, Jianwei Cheng, WANCHENG ZHENG, Gang Zhao, YUNGANG WANG, JIANBING ZHAO

Coal spontaneous combustion is one of the disasters occurring in underground coal mines. As a typical case, the spontaneous combustion of broken coal left in the longwall gobs often happen which could greatly interrupt the normal mining production. Such concealed thermal event is featured as rapid development and difficulty in locating “hot” spots. If such spontaneous combustion fails to be timely prevented and controlled, a large amount of toxic gases (mainly CO) and smoke could flow and diffuse in the underground working sections, which could present safety hazards for coal miners. In this paper, based on an coal spontaneous combustion event happened in a Chinese gassy mine, the fire ratios derived from the gas composition data obtained through the tube bundle mine atmospheric monitoring system are used in determining the fire status. A comprehensive and collaborative fire extinguishing effort including inert gas injection, underground pressure balance, and sealing enhancement are made to control the fire progress. Simultaneously, the effects of such works to control the spontaneous combustion event have also been quantified using the fire ratios to justify again. Finally, the danger of coal spontaneous combustion in gob is eliminated, and the longwall panel is successfully re-opened for normal production.

May 6, 2021

By Norbert Steiner, Roy Norcross

For the desulfurization of weak SO2 gas streams, Degussa developed a process using dilute H2SO4 solution containing H2O2 instead of conventional gas scrubbing with all solid absorbent medium (limestone, MgO). The process is based on fast reaction of H2O2 with SO2 yielding H2SO4 up to 70% strength, depending on off-gas tem­perature. Compared to the conventional systems with typically < 95% efficiency, independent on the raw gas SO2 concentra­tion, residual SO2 concentrations of less than 20 mg!Nm3 can be easily achieved, corresponding to nearly 100% removal. These features render the H2O2 process a very attractive, low capital cost technology to retrofit existing conventional desulfurization plants.

Jan 1, 1996

By Roger B. Jr. Herbert

Surface water samples were collected from water accumulations at the surface of a neutral pH mine tailings deposit in Kristineberg (Sweden) where algal growth and iron hydroxide precipitates were observed. Ferric iron in the aqueous samples was determined by (adsorptive) differential pulse - cathodic stripping voltammetry. The analyses indicated that labile Fe3+ concentrations were in the range <20 to 337 nM, while total Fe3+ levels were much higher at 0.9 to 8.3 uM. The labile Fe3+ levels are more than two orders of magnitude greater than would be expected based on equilibrium with ferrihydrite. These results suggest that iron complexation with strong ligands in the surface water competes with iron hydrolysis, and that these ligands may be of algal and/or bacterial origin.

Jan 1, 2000

By S. K. Kawatra

It is common in coal-cleaning operations to produce a fine waste stream which contains a considerable amount of coal, but which is not economical to recover both because it is mixed with large amounts of difficult-to-remove clay slimes, and because the fines are often heavily oxidized. Conventional froth flotation machines cannot produce an acceptable product from such material in a single stage of flotation, and even flotation columns often have difficulty cleaning this type of feed. A new type of flotation column was designed specifically to deal with these problems, and was installed and tested in a coal-cleaning plant in Ohio. The feed coal contained 39.8% ash as fine clay, and 2.83% total sulfur, and was 80% passing 176 micrometers. The coal was a thickener product which had oxidized for some time, and was very difficult to float. However, using the new column it was possible to recover up to 85% of the calorific value in a product containing less than 11% ash, and up to 60% of the calorific value in a product of less that 8% ash. The bulk of the pyritic sulfur was rejected from the coal as well. Multistage flotation tests showed that the flotation column was able, in a single stage, to produce the best froth flotation product that it was possible to recover from this coal.

Jan 1, 1994

By Matthew S. Sanchez, Richard J. Lee, Matthew D. Zock, Drew R. Van Orden, Yumi Kamiya, Edward B. Ilgren

In many developing countries, asbestos is still used for friction products, insulation, and asbestoscement products. However, there is very limited modern data evaluating the airborne concentrations of asbestos fibers in operating asbestos plants. We have conducted an Industrial Hygiene survey, using state of the art PCM and TEM analysis, of a Bolivian asbestos cement plant that uses crocidolite during the production of roofing shingles and water tanks. The study is the first to use modern analytical measurements in an uncontrolled asbestos environment. Thus, this study offers insight into the historical airborne exposures at asbestos plants operating before modern dust control measures were introduced or airborne fiber levels regulated. The results suggest that fiber concentrations are far in excess of those for which current models would predict the onset of asbestos disease and mesothelioma. Significantly, the plant and community do not have an elevated incidence of asbestos disease or mesothelioma. Airborne fiber levels during comminution and fiber sizing ranged from 100 to as much as 1,000 f/cc. Fiber levels in the mixing, forming and finishing areas ranged from 0.5 to 9 f/cc. Based on the number of overloaded samples and estimates of their concentration, historical estimates of exposure may be underestimated by an order of magnitude. Also, an excellent correlation (1:1) between the PCM and TEM fiber concentrations (for fibers _0.25 um diameter) were obtained, raising questions about the conventional wisdom that the PCM systematically undercounts fibers. The results of this study further indicate that current models may overestimate the risk of asbestos disease and mesothelioma.

Jan 1, 2012

By J. M. Dean

The MANpower SUPport Program (MANSUPP), a part of the Mine Management Support System (MMSS), allows an underground coal mine site user to determine manpower requirements for production support work by considering ongoing operations and current mine conditions. The objective of MANSUPP is to plan a detailed manpower structure for a mine by incorporating a production schedule, condition-modified work standards and management preferences to predict required manhours for various activities, for example, belt moves. The program is written in Quattro Pro version 3.0 (Lotus 1-2-3 compatible) utilizing the command language, macro and formula capabilities.

Jan 1, 1992

By J. A. Marts

Reservoir properties including porosity and permeability distributions in longwall coal mine gobs have direct application to modeling the flow patterns and gas distributions in the gobs. Proper assessment of these distributions is required to assess gob gas hazards such as spontaneous combustion and explosive methane mixtures and to optimize gob gas venthole operation and nitrogen inertization. Determining the reservoir properties is difficult given that the gob is inaccessible and direct measurements cannot be easily taken. Several techniques have been used by previous researchers and will be discussed. This paper will present the methodology used to model the gob compaction by simulating the sequential extraction of coal. Two Western US coal mines were used for case studies. By determining volumetric strain, the porosity and permeability distributions in the gob can be calculated. The geo-mechanical model predicts an axisymmetric volumetric strain distribution with a steeper slope near the start-up room and a shallower slope near the active face.

Feb 23, 2014

By Frank Pollard

The Australian coal industry over recent years has experienced the situation whereby exploration and mine development are moving into geographical areas where the coal seams have never been mined to any extent in the past, if at all, and particularly where there is no history of experience in preparation of these seams. Additionally, the demands have been such that the development of a mine up to production stage should proceed with minimum delay. This is a situation which is of some importance and concern, in view of the coal quality requirements now experienced within world markets which can only be met, in most cases, by careful preparation. Costs are such that the preparation plant should operate as required by the situation and with maximum efficiency, which means that laboratoty information of breakage and washability characteristics which are required for preparation plant design should be accurate and available as soon as possible, even to a certain extent during the progress of the exploration.

Jan 1, 1981

By D. D. Schlepp

There is a continuing debate about the influence of circulating load and classifier efficiency on the capacity of the circuit. Specifically, the effects of preferential classification, bypassed fines, and the sharpness of classification will be examined. Horizontal cyclones have also proven to be very successful in a number of operations but their impact on the circuit capacity has not been clearly defined.

Jan 1, 1990