Search Documents

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was not covered was accounted for by companies that chose not to participate in the SNL survey, private companies that do not publish their budget data, and government-funded exploration activities."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 C. E. "Sam" Lovewell

In approaching a discussion of production of cement, I hope I won't be like the porter in the bank who was asked if he could give some details on the rediscount rate. He replied, "Boss, when I said hello, I told you all I know." Need for change every so often is illustrated by the story of the little boy four years old who had not spoken a word in those four years. One morning he said, "This damned oat meal is burned'." His Dad was amazed and said, "Son, how come you haven't said a word for four years and now out of a clear, blue sky you say, "The oat meal is burned." Johnny said, "Well, up to now everything has been all right." Not being a mining engineer myself, and my subject not dealing with mining engineering directly, I can only hope that you will agree that the subject has current relevancy by the feet that it can materially improve our environment by putting to good use a potential environmental polluter; namely, fly ash. The profitable utilization of fly ash can reduce cost of use of coal as an energy source. Therefore, it behooves us all to explore to the greatest depth, the pluses and minuses occasioned by its use wherever possible. My particular subject and my particular interest lie in its utilization as a blend in the production of Type IP Portland-Pozzolan Cement meeting requirements of ASTM C-595, Type IP.

Jan 1, 1974

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 Muhammet Mustafa Kahraman

Despite technological advancements and organizational adjustments, lost time accidents are major issues in occupational safety. However, there is very limited work that focuses on variables influencing days lost as a result of occupational accidents. In this study, decision tree and artificial neural network methods were used as machine learning techniques to investigate the impact of factors on accident lost day duration. Degree of injury, worker age, and worker activity were found to be the top three variables impacting loss of time from work. It was also identified that the mining method, location, and nature of injury had a moderate influence on duration lost due to occupational accidents. However, worker experience and ore type did not have any significant impact on the duration, which is an unexpected result. These results confirmed that some accident factors that might have a large influence on the number of mine accidents can be less critical when it comes to accident lost day duration.

Feb 3, 2021

By K. Terhaar

The objective was to determine operating protocols for a lead and silver column flotation cleaner, being considered for installation at Sunshine Mining & Refining Co.'s Kellogg mill in Northern Idaho. In this column, tetrahedrite and galena were floated, and pyrite and other gangue minerals, including siderite and silica, were depressed. The procedure was to develop a dynamic simulation using a linear transfer function approach. The transfer function related cause and effect variables such as the influence of collector and depressant dosages on recovery and grades. Bench-scale flotation tests followed by pilot column testing provided the data used to develop a linear transfer function. The transfer function was derived using a spreadsheet. This model was applied to simulate how the flotation column could be made to respond to disturbances in feed grade. The results were that xanthate, zinc sulfate, and sodium cyanide were found to be suitable controls for grade and recovery. Simulations showed the best sequence of manipulations of these reagents, and these sequences were useful for future operator training. The conclusion was that linear transfer functions were able to simulate lead and silver recovery, develop scenarios for operator training, and provide a foundation for future on-line control.

Jan 1, 1999

By Mads Aniksdal

New Nedre Fiskumfoss is a construction project in North Trøndelag, Namsen River. The purpose of the contract is construction of a new hydropower plant, that will phase out the existing power plant in the same waterfall. The contract consists of a tunnel system with cross sections from 16 m2 to 150 m2, powerhouse and transformer in rock caverns, 6 shafts and major works with inlet and outlet below river level. Technical challenges consist of demanding design on rock extraction, cofferdams, solid constructions with challenging design and demanding rebar work, as well as restrictions and unpredictable water flow in a national salmon river.

Jun 13, 2023

By Lana Alagha, Fardis Nakhaei, Jose L. Corchado-Albelo

Tellurium (Te), a critical mineral for solar energy technologies, faces supply risk challenges that drive the development of diversified and robust production routes. This research focused on improving Te enrichment from copper tailings (CT) produced from copper porphyry (CP) ores processing, addressing the loss of ~90% of Te minerals to tailings in the flotation process of CP ores. Gravity separation and froth flotation processes were used as possible enrichment routes of Te-bearing minerals (i.e., pyrite) in CT. In the froth flotation process, synergistic combinations of reagents were tested to achieve an acceptable enrichment ratio of Te minerals. Comprehensive characterization analyses showed significant Te enrichment in the flotation concentrates. Tellurium was recovered at 90%, while the grade of Te in the concentrates was 1.4 ppm using a xanthate collector and glycol frother compared to <0.5 ppm in the flotation feed. Findings showed that Te-minerals’ enrichment was also feasible in CT using the proposed combined concentrations routes (i.e., gravity separation followed by froth flotation) by looking at Fe, Cu, and S enrichment. This study also highlighted the importance of understanding the deportment of Te minerals in different process streams to develop and optimize efficient enrichment practices.

Feb 1, 2024

By John Rajala

The Otjikoto Gold Mine in the Republic of Namibia is located approximately 300 kilometers north of the capital city of Windhoek. The project features surface mining with a modern gravity/carbon-in-pulp mill for ore treatment and recovery of gold. Initial mill design capacity was 2.5 million tonne per annum but then expanded after 9 months of operation to 3.1 million tonne per annum. The technical steps to establish the Otjikoto mill design from process selection in the due diligence stage, through flowsheet development in the feasibility study followed by detailed engineering design are reviewed in this paper along with mill performance during start-up and in 2019.

Oct 30, 2020

By William G. Pariseau

The purpose of this paper is to present a discussion of the various approaches that can be utilized in the study of mine subsidence phenomena. Attention is focused upon the rational selection and use of laboratory models. Broadly interpreted, mine subsidence is the deformation of the rock mass enclosing the mine. Depending upon a number of factors, the movement of the subsiding rock mass may be such as to disrupt gas and water lines or other buried utilities, to damage surface structures such as buildings and bridges, to dislocate streams, roads, and rail lines, to aggravate acid mine drainage and fire problems, and to generally mar the landscape. It is clearly a problem that no mine manager can safely ignore. It is also a problem that will grow with the general population increase. In the following, a summary review of past and present approaches to subsidence studies is given. The possibilities of duplicating subsidence phenomena in laboratory models are examined, and an analysis of a particular type of model is presented. Some preliminary results obtained from a model of the particular type analyzed are then discussed.

Jan 1, 1968

By P. A. Roberts

A proposal for a modified in situ leaching method for extracting gold from oxidized gold ores using a non-cyanide lixiviant is described. A non-cyanide lixiviant is suggested because of the obvious concerns posed by injecting cyanide-bearing solutions into the subsurface. Oxidized gold ores were chosen as a focus because earlier research on the use of sodium thiosulfate as a lixiviant under anaerobic conditions indicated that the presence of pyrite led to rapid thiosulfate breakdown. A reconnaissance research program involving ore characterization and hydrometallurgical test work on samples from four Australian ore deposits and preliminary reactive transport modeling studies was carried out. This work showed that lixiviant-oxidant combinations of sodium thiosulfate and ferric EDTA and iodide and iodine are both capable of extracting high percentages of accessible gold from the selected samples in bottle roll tests under anaerobic conditions. The ore characterization and reactive transport studies suggested that both physical and chemical methods of permeability enhancement may be required to lift bulk permeability and the availability of gold for dissolution to sufficiently high levels to obtain adequate gold recoveries. Assuming that such methods prove to be both necessary and economically viable, the mining method would no longer be regarded as simple in situ leaching. Therefore, the term ?in-place leaching? has been adopted for the proposed gold extraction system.

Jan 1, 2010

By H. M. Brennecke

A new hydrometallurgical process has been developed to recover copper from sulfide ores. Copper is leached in a staged reactor system utilizing nitric and sulfuric acids at 105°C. Iron is removed from the pregnant liquor as a jarosite and cathode copper is electrowon directly from the purified pregnant liquor. The spent electrolyte is recycled. Nitrogen oxides evolved from the leach are reconverted to nitric acid and are also recycled. Sulfur is rejected as S°, jarosite and gypsum. The process is highly versatile and can recover precious metals, molybdenum and zinc, when these elements are present. Continuous, integrated, semi-pilot plant operations using chalcopyrite ores demonstrated 99% copper leaching and production of cathode grade copper. Economic evaluation shows that the process is competitive with pyrometallurgical and other hydrometallurgical processes.

Jan 1, 1978

By Harvey P. Knudsen

This paper illustrates the application of geostatistics to a roll front type uranium deposit located in Wyoming. The steps involved in calculation of experimental variograms, variogram modeling and verification of the resulting models are described in detail. The resulting spherical variogram models for grade thickness and thickness show strong geometrical anisotropies. The major axis of anisotropy for both variables is approximately parallel to the axis of the roll front and the minor axis perpendicular to the roll. This model confirms the technique of drilling "fences" across the roll front, where the drilling is much closer together than the fences along the roll.

Jan 1, 1978

The past four years since the 2008 MINExpo have been a roller coaster ride for the mining industry, with highs and lows and everything in between. One of the natural consequences of this uncertainty has been a number of significant consolidations and mergers, and this trend has trickled down into the crushing industry. And while there have been some significant changes to this sector of the mining industry, many of the big players have weathered the storm. The following is a look at some of the mineral processing companies that will be at MINExpo. McLanahan Corp. McLanahan Corp. is an example of the changes in the sector. The crushing and grinding stalwart acquired Universal Engineering, expanding its traditional focus on soft mineral crushing to hard rock crushing. At MINExpo, it will be showing off three new pieces of equipment, the LabMill Crusher, the Rocker Tooth Crusher and the Recessed Filter Press.

Jan 1, 2012

By Peter G. Dunn

Geologic studies during development at Copper Flat were directed at acquiring the information necessary in evaluating a low-grade porphyry copper deposit. In addition to the geologic mapping and core-logging of a typical exploration project, these studies included the following : (1) careful checks on the sampling and assaying (2) selection of representative samples used to establish the recoverable amounts of precious metals in the ore (3) examination of underground workings driven to provide samples both for metallurgical testing and for assay comparisons (4) evaluation of plant site and waste dump areas as non-mineral, including a placer examination of the taillngs disposal area (5) location of an adequate water supply. All these investigations were carefully documented to provide the necessary data both for the engineering design and, more importantly, for the feasibility studies required for successfully financing the project.

Jan 1, 1981

By Patzen Wu

Taiwan is located in the orogenic belt of island arcs on the western rim of the Pacific Ocean. The structure of the Taiwan coal fields is much complicated as a result of active Cenozoic orogenic disturbance in Plio-Pleistocene time. The abundant faults and folds have created poor structural conditions of the coal seams and some peculiar safety problems in mining however, the domestic coal still played an important role in the economic development of Taiwan for the years before 1968. Because of increasing mining depth and a decreasing number of miners, the coal production dropped from nearly 5.1 million metric tons in 1968 to 2.45 million metric tons in 1981. There were 173 small active coal mines and about 22 thousand miners in 1981. The coal mining in Taiwan has a history of more than one century. Specific efforts have been undertaken in solving major coal mine safety problems such as gas outbursts, bad roofs and weak floors, difficulty in ventilation due to deep underground mining, spontaneous combustion etc. We have thus acquired much helpful experience which, we deem, is worth reporting at this meaningful meeting.

Jan 1, 1982

By Yuting Xue, Alper Kirmaci, Taghi Sherizadeh, Khaled Mohamed

Resin-grouted bolts serve as a crucial means of stabilizing yielded coal ribs in underground coal mines. A comprehensive investigation into their efficacy was undertaken by a collaborative effort between the National Institute for Occupational Safety and Health (NIOSH) and Missouri University of Science and Technology (MST). This study involved pull-out tests in multiple locations, including six coal mines and the NIOSH research mine. A total of seventy-three (73) tests were conducted, of wide range of anchorage lengths, ranging from a short encapsulation length of 0.305 m to a fully grouted encapsulation length of 1.524 m. The test findings indicate that when short encapsulation bolts are installed at high rotation speeds, their anchorage capacity is significantly reduced, leading to failure at the bolt-grout interface. Conversely, when these bolts are installed at lower rotation speeds, they exhibit greater capacity, with failure occurring at a higher anchorage load equivalent to the yield load of steel rebar. No matter what the rotational speeds were used during bolt installation in this study, the fully grouted bolts consistently experienced failure at the ultimate load of the steel rebar. Most of the tests carried out on partially grouted bolts with anchorage lengths of 0.610 - 0.914 m have shown behavior patterns like the fully grouted bolts, although exhibiting reduced stiffness. The outcomes of this research offer a profound insight into the ways in which resin-grouted bolts enhance the stability of coal mine ribs.

Feb 1, 2024

By Yanli Huang, Qiang Sun, Jixiong Zhang, Yuzhuo Jiang, Dan Ma

Mining accidents due to inrushing water are caused by sudden changes in seepage owing to structural damage to key strata of the aquiclude. The backfill mining method can be used to control the movement of the strata, weaken the evolution of fractures owing to damage by key aquiclude strata (KAS), and control the channel for inrushing water. This study develops a mechanical model of a composite beam on a non-uniform elastic foundation of the KAS by analyzing the coupling relationship between the filling body and the key water-resisting layer of the aquiclude. Equations of the deflection-induced deformation, bending moment, and maximum tensile stress of the KAS are analyzed, formulae to calculate the allowable tensile stress and backfill materials’ compaction ratio (BMCR) to ensure structural stability are derived, and are used to provide the critical BMCR for their structural instability. The results of field measurements show that the subsidence of the roof was 600–700 mm with an average BMCR of 80.63%. Damage to the overlying strata was controlled to ensure safe mining and the disposal of solid waste from the aquifer. The research here is useful for ensuring safety during mining while protecting water resources.

Jul 12, 2022

By R. M. Powers

The Florida Institute of Phosphate Research (FIPR) has funded a four-year research project to develop a computer model &apos;which will predict the hydrologic impacts of phosphate mining on surface and groundwater systems. The core of the model is an analytical geographic information system (SPANS) which integrates EPA&apos;s Hydrology Simulation Program Fortran (HSPF) surface water model with the McDonald-Harbaugh groundwater model (MODFLOW). The hydrologic model conducts both event and continuous annual Simulations driven by variable precipitation and temperature data. The model is currently being calibrated and will be ready for distribution to the user community in mid-1991.

Jan 1, 1990

By G. V. Henderson

Large reserves of high calcium limestone have been outlined in the Redwall formation at Nelson, Arizona. Geologic mapping, core drilling and shallow seismic refraction studies have outlined more than 100 million tons of high quality, chemical and metallurgical grade limestone in the Mooney Falls member of the Mississippian Redwall Limestone. Well developed Karst zones in the Redwall were delineated by field mapping, seismic profiling and core drilling. Development of large reserves of high quality, thick beds of limestone near the present mine and rail facilities was the basis for the current mine and plant expansion. When completed in 1978 the planned 1800 Tpd production will represent the largest lime operation in the Western United States.

Jan 1, 1978

By Jianping Zuo, Chunlei Zhang, Yong Zhang, Shouyang Gao

To study the fracture evolution of overlying strata for ascending mining in a short-distance coal seam group, a two-dimensional physical simulation model was designed based on a specific geological condition. The fracture development zone was divided into the compaction zone and active zone by monitoring and analyzing the macro fracture evolution of the surrounding rock mass during the excavation of multiple coal seams. The secondary fracture development process of the overlying strata was demonstrated with a physical model. The quantity, length, and inclination of the fracture were calculated with MATLAB software, and the results were verified by geological radar. The total number of fractures between two coal seams increased with a “parabola” shape during the excavation of the lower coal seam, the crack angle was mainly vertical and horizontal, and the number of horizontal cracks first increased and subsequently decreased; the excavation of the upper coal seam caused the secondary fracture development process of the overlying strata, and the relief range and its extent increased. The mining-induced cracks from the lower and upper coal seams connected with each other, especially the permanent vertical fracture in the cutting room side and face side. Finally, the three-dimensional gas fissure was formed.

Nov 24, 2020