Search Documents

By Dominik Hofer

A broad spectrum of tantalum containing input materials can be processed for the production of synthetic tantalum concentrate (“SynCon”). The use of these low grade substances offers a secure alternative to mining of coltan in Central Africa. SynCon is produced in a multi-stage pyrometallurgical process, wherefore the melting behaviour of slags presents an important factor especially regarding the energy consumption and its optimisation. The characteristics of a slag comprising mostly Al2O3, CaO, SiO2 and MgO are influenced by the amount of other oxidic constituents which enfolds the main focus of this study. A hot stage microscope serves for the investigation of the slag behaviour in a temperature range from 1000 to 1600 °C under reducing atmosphere (CO/CO2 gas). The experimental results are compared with thermodynamic calculations (FactSage) to get a better understanding of the process.

By B. E. Davis

A problem that has continued to plague the Florida phosphate industry is the loss of coarse phosphate in the flotation circuit. Attempts to remedy this problem such as floating the coarse material (plus 425 µ m) in a separate circuit have resulted in limited success, but recovery is still not optimum. The Bureau of Mines is investigating ways to improve the recovery of coarse phosphate through improvements in the conditioning step. Studies to optimize conditioning parameters such as agitation energy, conditioning time, conditioner solids, and residual clay content have resulted in improved P2O5 recovery. Optimizing these and other conditioning parameters resulted in a rougher concentrate grading 30 pct P2O5 with a P2O5 recovery of 97 pct.

Jan 1, 1993

By R. C. Emmett

The industrial practice of concentration of solids and production of clear solution by gravity sedimentation is an old technology. Through the years, many devices have been designed and built to aid this process. One of the more significant developments was a revolving rake mechanism to convey settled material to a central discharge point of a circular tank, patented in 1907(1). In recent years, clarification systems employing parallel inclined plates have appeared on the market; the original device utilizing this principle was patented in 1886(2). Numerous other methods have been invented, tested, discarded and sometimes re-invented, all with the specific intention of improving the capacity of a particular settling area. Sedimentation theory, as expressed in Stokes' Law, shows that the rate of settling of a particle is directly proportional to the difference in density between the particle and the surrounding liquid and, more significantly, proportional to the square of the particle diameter. Anything that can increase the latter will greatly assist sedimentation and, as a result, flocculation always has been an integral part of sedimentation. Most materials suspended in aqueous media are naturally flocculent to some degree and, hence, are readily concentrated by sedimentation, although sometimes very slowly.

Jan 1, 1978

By Q Liu

Open stoping is one of the widely adopted methods in underground bulk mining. In this method, fanned or parallel holes are often drilled from a top sill down to a sublevel in the ore zone and blasted ring by ring into a stope for excavation. A mass stope blast may involve blasting rock from multi-level drift rounds and displacing the muck to specific locations in order to allow safe and easy access for ore removal. This paper presents a strategic mass stope blast that took place at a large lead and zinc underground mine in eastern Canada. The blast consisted of more than 800 holes drilled in six blocks from three different sublevels. The challenge lay in the control of ground vibration and muck movement using precise timing to complete the blasting within 6.5 seconds. During this time span, sufficient voids were created in each level to allow the muck to move from the upper to the lower levels in sequential order across the six mining blocks without bridging. This paper describes stope blast simulations using a discrete element computer code for modeling blast-induced rock displacement as well as the application of electronic detonators. These detonators provided the means to accomplish the desired firing sequence including a drop raise blast at the start of the mass blast. The modelling concept is also described in the paper.

Jan 1, 2005

By S. C. Torma

Sources of lead contaminated soils are numerous, i.e., the uses of leaded gasoline, lead-based paints, leaded pesticides, solders, smelting of lead concentrates, refining of lead products, automobile demolition, recycling of lead batteries, and so on. Conservative estimation by the US Environmental Protection Agency, EPA, indicated that several thousand lead contaminated sites are awaiting remediation. The current remediation technologies include immobilization, reclamation and soil washing. In this paper, the above remediation technologies will be reviewed, and where appropriate, the economics of processes discussed and future possibilities indicated.

Jan 1, 1996

By D. J. Buchanan

British Coal's mining research programme is directed towards the strategic objectives of reducing production costs, improving product quality and resolving health, safety and environmental issues. The strategy for R&D is described and selected parts of the programme are reviewed. Two major initiatives are directed towards reducing production costs: geotechnics and automation. Integrated exploration techniques are used to delineate geological structures as an aid to mine planning. Rockbolting is being rapidly introduced and the in situ stress field has been found to be of significant influence. Automation is the subject of a major programme. A strategy for coal quality has been devised. The health, safety and environmental programme concentrates on the traditional hazards together with surface environmental problems.

Jan 12, 1992

By Fulian He, Jianhang Chen, Dongdong Chen, Shoubao Zhang

"The Wangjialing Coal Mine is the main colliery of the China Coal Huajin Energy Limited Liability Company. The average thickness of the coal seam in District 201 is 6.21 m. Fully mechanized longwall mining was used in this district. The ventilation roadway of panel 20102 was influenced by the retreat mining of the adjacent panel 20104. Therefore, large deformation and severe roof falls occurred in this roadway, seriously influencing the safety production of this coal mine. To support the roadway, cable truss was proposed to strengthen the reinforcement of this ventilation roadway. First, numerical simulation was used to optimize the reinforcement parameters, including the cable installation angle, cable length, and eccentric distance. Based on numerical simulation results, in-situ tests were conducted in the ventilation roadway of panel 20102 with the cable truss technology. In-situ monitoring results showed that the roof-to-floor convergence and the convergence of roadway on two sides were within the safety range. Furthermore, no apparent separations occurred in the roof. These indicate that based on the designed parameters, the cable truss system can effectively maintain the roadway stability under the severe influence of the adjacent longwall mining.INTRODUCTIONCable bolts are flexible tendons composed of multi steel wires, which are wound into a strand (Chen, Hagan, and Saydam, 2018). They were initially introduced in the hard rock mining industry in the 1960s. Later, they found rapid application in coal mines to maintain the stability of excavations (Wang et al., 2015).The standard cable bolt is composed of seven steel wires with a diameter of 15.2 mm. Laboratory and in-situ tests showed that there is a low bonding capacity between the standard cable bolt and the grout (Craig and Holden, 2014; Chen, Hagan, and Saydam, 2018). Then, modified cable bolts are developed based on the standard cable bolts. They are improved by changing the surface geometry of standard cable bolts, such as birdcaged cable bolts (Hutchins et al., 1990) or nutcaged cable bolts (Hyett et al., 1993). Further tests proved that modified cable bolts have better mechanical interlock and friction between the cable bolt and grout, leading to larger load transfer capacity of cable bolts.Although cable bolts have been used for many years, failure of the cable bolting system still occurs. A common failure mode is the damage of surrounding confining medium while the cable bolt is still hanging in the roof, which is caused by the bond failure of the cable/grout interface (Hutchinson and Diederichs, 1996). To prevent the cable bolting system from failing, the cable truss system is more widely used in mining engineering."

Jan 1, 2019

By Jon C. Volkwein

The Bureau of Mines conducted a series of tests to evaluate the effectiveness of mixing a compressed-air-generated foam with dried whole-grain silica sand to suppress dust in minerals processing plants. Dust at downstream transfer points was monitored with personal gravimetric samplers and with Real-Time Aerosol Monitors (RAM's) that were connected to strip' chart recorders. Results showed dust reductions of 80 to 90 pct on three separate occasions at two different plants. The mechanism by which foam suppresses dust is discussed, as are the constraints on the use of foam, which may include incompatibility of the foam with the mineral product, difficulty in controlling the foam generator, and cost.

Jan 1, 1983

By Chris Strawson

Moranbah North is a modern longwall operation mining premium coking coal in the Northern Bowen Basin, Central Queensland. Australia Moranbah North Coal (MNC) is owned and operated by Anglo Coal Australia. Extracting approximately 4.5m of the Goonyella Middle seam using a single longwall, the mine produces 5 to 6 Mt per annum. The weak coal (4.5 MPa), low strength laminated immediate roof, and strong upper roof sandstones, make operation of the longwall at depths in excess of 250m geotechnically challenging. In the past, there have been a number of production delays due to geotechnical issues. Roof instability resulted in a long stoppage on Longwall 105, and the eventual relocation of the face further outbye in the block. (Figure 1). When mining commenced in LW106, there was a requirement for uninterrupted production, particularly in the more demanding inbye area of the panel. Following discussions with a number of Geotechnical experts, it was decided to narrow the face, and test the theories of reduced face weighting due to spanning of the goaf across the panel. A new on line chock monitoring system, and microseismic monitoring was installed in order to characterise the difference in the rockmass response, as the panel width changed from 175m, to 265m, and then 300m. The nature of the goaf formation and impacts on face loading and production are discussed, having the unique opportunity of three different face widths within the same area.

Jan 1, 2007

By Boyd Davis, Vladimiros Papangelakis, Joshua LaMarre, Jan de Bakker

"HCl leaching using molten salt hydrates has the potential to improve the extraction of nickel from laterite ores. However, as in other HCl leaching applications, recovery of HCl is key to process economics. Spray pyrohydrolysis, which is used in current chloride-based flowsheets, is associated with a high energy cost. The authors have developed a proposed laterite leach circuit using an alternative HCl recovery route. The leach circuit envisions a leach by concentrated (33%) HCl in an MgCl2 molten salt hydrate (MSH) or brine medium, followed by Ni/Co recovery and iron precipitation. Magnesium and chloride are precipitated from solution as magnesium hydroxychloride; this hydroxychloride is thermally decomposed to produce HCl gas. The proposed flowsheet employs a chloride leach circuit with simpler equipment and lower energy cost than in the conventional practice of pyrohydrolysis. Laboratory work investigated key aspects of the flowsheet, including precipitation of magnesium hydroxychlorides and their composition; magnesium hydroxychloride thermal decomposition; and iron control.Introduction As sulphide nickel ores become harder to mine and more complex to process, laterite ores will increase in importance. Laterite ore deposits can be divided into two main mineralogies. Limonite ores consist mostly of hydrated iron oxide, FeOOH, with 1-3% nickel substituting for the iron. Saprolite ores consist of iron-magnesium silicates, (Fe, Mg)2Si04, again with some nickel substituting for the metal ions. Limonite ores can be treated using the HP AL (High Pressure Acid Leach) process, in which the ore is reacted with sulphuric acid at high temperature in an autoclave. HP AL, however, cannot in general be used to treat saprolite ores because the magnesium enters solution and consumes sulphuric acid, which results in excessive spending on lixiviant. It is therefore desirable to find a hydrometallurgical process specifically for saprolite ores that can provide better results than the treatment options currently available."

Jan 1, 2011

By H. Tomlinson

This circular is one of a series of papers on coal mining methods and costs which being prepared by the United States Bureau of Mines for the purpose of making available to those interested in the industry a knowledge of the mining methods employed, the places here mechanical and hand loading are practiced, and coat data on the several operations pertaining to the removal of coal from the working faces and its transportation to the tipple for loading into railroad cars. Mining costs are governed by the relative efficiency of the mining method employed. The method is selected for Its adaptability to the local natural physical conditions such as the nature and thickness of the coal bed, its dip, the character of the coal, and the thickness of the overlying strata.

Jan 1, 1930

By Michael E. Karmis

New and developing communication systems en-able underground miners to, not only connect to the surface from an increased communication coverage area, but also to be discovered in the event of an emergency. Communication and tracking systems are required by the U.S. Mine Safety and Health Ad-ministration (MSHA) regulations, aiming to enhance health and safety and routine production in underground operations. Modeling a mine?s potential communication coverage area will increase overall coverage and efficiency of the communication network itself. Modeling the propagation of wireless communications enables ideal broadcast locations to be found when designing a communications network. Strategic placement of broad-cast devices results in a reliable communication network that can better withstand disruption in daily operation and during a time of emergencies. Research on wireless communication in mines has been ongoing since 1922, when the U.S. Bureau of Mines performed experiments in its experimental mine in Bruceton, PA (Schiffbauer & Brune, 2006a). Ac cording to Dobroski and Stolarczyk (1982), ?as early as 1922, Bureau of Mines experiments showed that radio propagation in mines was possible but not practical.? In 2006, the underground communication technologies available to the mining industry had inherent problems that limited communication capabilities. Because harsh underground mine environments significantly reduce line of sight and propagation range and introduce power and safety concerns, the overall effectiveness of underground communication technologies were limited. After several coal mining accidents in early 2006, the U.S. Congress responded with the Mine Improvement and New Emergency Response (MINER) Act, enacted

Jun 1, 2010

By A G. L Pratt

Change and its relationship with the introduction of new technology is a constant of human history. The mining industry has many examples of this relationship. This record contrasts with its present day struggles to move beyond a public perception of being just ‘dirty, dumb and dangerous’. The drivers for the introduction of new technology are frequently listed as the occupational health and safety of people working in the mines, reductions in direct operating costs, and increases in productivity.This paper discusses the issues that a mining business needs to deal with to implement new technology with the best possible conditions for success. It comments on how the strategic and tactical components of technology planning relate to and interact with change management. The central discussion is directed at the role that people play in the successful implementation of new technology. The introduction of autonomous underground haulage equipment provides a background for the discussion of this topic.The paper uses case study references, equipment supplier information and research findings. The aim is to offer a high-level view of the issues a mine operator needs to consider when approaching the introduction of new technologies for underground mining.CITATION:Pratt, A G L, 2017. Technology change in underground mining – things to consider, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 103–114 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By W. A. Smith, M. C. Bekker, C. Marnewick

Projects or project-orientated approaches have become a common form of work in nearly all sectors of economies. This has led to concepts such as ‘projectified’ and ‘project orientated’ organizations. By defining projectification of a company, industry, or economy as the share of project work in total work, one can reasonably determine the impact that project management, and by default projectification, has had on that company, industry, or economy in terms of staff optimization and allocation. This paper presents the results for such a projectification study of the South African mining industry. This sector has long been a significant contributor to the country’s economy from a gross value added (GVA) and employment point of view. Understanding the impact of projectification and the project management way of work on this industry may potentially add significant value to both the mining and project management knowledge areas. We show that although the mining industry is considered by some to operate in archaic ways, the level of projectification has increased over time, and now represents approximately one third of all work conducted.

May 1, 2021

By D. Bienstock

A high-B.t.u, gas can be synthesized by the catalytic methanation of a mixture of 2.5 to 3 parts of hydrogen to 1 part of carbon monoxide, obtained in the gasification of coal, using a steel catalyst followed by Raney nickel in a hot-gas-recycle system. Conversion of 99 percent of the H2+CO yields a fuel gas with a heating value of 983 to 1130 B.t.u. per cubic foot containing 78 to 96 percent methane, no carbon monoxide, and very small amounts of unsaturated hydrocarbons. With the steel catalyst alone, conversions were 85 to 90 percent, giving a fuel gas of 810 to 868 B.t.u, per cubic foot, or 847 to 975 B.t.u. on a C02-free basis. INTRODUCTION In 1948 the U.S, marketed production of natural gas was 5.15 trillion cubic feet; by 1958 it had reached 11.0 trillion cubic feet, a rate of growth of 8 percent annually. 4 5 Although demand is expected to increase less rapidly, by 1966 it may reach 16 trillion cubic feet, based on an estimated 4.7 percent annual increase.6

Jan 1, 1961

By K. Yoo

Cuprous oxide is one of the oldest antifouling agents and also acts as red pigment in these paints. In printed circuit board manufacturing industries, waste etchant contains a substantial amount of copper ion. In the present study, a process was suggested for recovering cuprous oxides from the waste etchant and optimum conditions were investigated to recover the cuprous oxides. The process consists of two steps: in first step, Cu powder is added into wastewater solution, and cupric ions re-duce into cuprous ions (Cu+Cu2+?2Cu+), where cuprous ions precipitate as cuprous chloride; In second step, cuprous oxide is synthesized by adding NaOH into cuprous chloride solution (2CuCl+2NaOH?Cu2O+NaCl+H2O). Optimum conditions were investigated to recover cuprous oxide in the processes. When copper powder was added into wastewater with copper ions, Cu concentration decreased from 15.6% to 2.6% and ORP decreased from 620 mV to -59.9 mV. This result shows that cupric ions reduced into cuprous ions. XRD data indicated that the precipitate was cuprous chloride powder. Using the cuprous chloride recovered and NaOH solution, cuprous oxide was synthesized. To investigate the optimum condition, various NaOH solutions were added into water with CuCl, and then pH, ORP, Cu concentration, Cu contents in precipitates were analysed. XRD data showed that main component of precipitates was cuprous oxide.

Jan 1, 2014

By J. H. Howard

The purposes of this report are to summarize the findings of the Committee on the Challenges of Modern Society Non-electrical Project (a working committee of the North Atlantic Treaty Organization) and also, thereby, to provide an introduction and review of the current situation regarding non-electrical applications to those who are interested in the subject.

Jan 1, 1975

By T. J. Close

The Silver Peak Range North Wilderness Study Area was deleted from the list of US Bureau of Land Management lands in Nevada to be considered for wilderness designation. This decision was based in part on the US Bureau of Mines mineral investigation of the wilderness study area which found indications of precious- and base-metal-resources. The study area lies between the Silver Peak and Dyer mining districts of west-central Nevada. The Bureau examined 13 mineralized sites, most of which were previously unknown and unclaimed. These sites are along two zones that cross the study area from the Silver Peak mining district to the Dyer mining district. The two zones transect a volcanic center of fractured and altered rocks that contain epithermal veins of quartz and calcite with gold, silver, and base-metals. At the surface, these veins are poorly defined. Exposures of the more than forty veins examined were as thick as 17 ft and as long as 1000 ft. Samples from these veins contained significant amounts of precious- and base-metals-as much as 0.02 oz per ton gold, 2.1 oz per ton silver, 1.0% copper, 2.6% lead and 0.4 % zinc. No vein large enough or of high enough grade to be classified a mineral resource was disclosed by the sample data. However, most do have indications of precious- and base-metal-resources at depth. Subsurface exploration of some of the veins is recommended.

Jan 1, 1995

By B. Friedrich, A. Weyhe, H. Heegn

"Nickel-metal hydride batteries (Ni-MH) are storers of electrochemical energy, which have a higher specific storage capacity than lead or nickel-cadmium batteries. The demand for Nickel-metal hydride batteries is increasing rapidly since their market launch in the early 1990’s. Today there is no suitable and sustainable recycling process to recover nickel, cobalt and rare-earth metals. The discarded batteries are used today in the steel industry as alloy material because they contain nickel. Cobalt and rare-earth metals (RE) are lost; they are non-recycleable.In a German governmental funded research project, IME Aachen, ACCUREC Mühlheim and UVR-FIA Freiberg are cooperating in processing as well as in creating a feasibility study. The target of this project is the development of a new recycling process for metal recovery from Ni-MH-batteries. The proposed process described in this paper consists of a combination of mechanical, pyrometallurgical and hydrometallurgical processing steps. This process is capable of treating all types of Ni-MH-batteries. After comminution steel and organics are separated. The separated Ni-MH is smelted in an electric arc furnace. The products are a nickel-cobalt alloy and a slag phase enriched with rare-earth oxides for further treatment to ‘mischmetal’. Both the Nickel-Cobalt alloy and the ‘mischmetal’ will be directly used in battery production."

Jan 1, 2003

By Robert S. Sanford

Intensive investigations of domestic manganese deposits were conducted by the Bureau of Mines and the Geological Survey during the earlier part of the war minerals investigations when there was doubt that the quantity of manganese needed to produce the greatly increased tonnage of steel demanded for war supplies could' to obtained from its customary sources. Domestic deposits of ores that contain sufficient manganese for direct production of ferromanganese essential in steel Manufacture are generally small, and the bulk of the supply is imported. One of the few large deposits of low-grade manganese ore known in the United States is in the Artillery Peale district in southern Mohave County, Ariz. Manganiforous sediments underlie a very large area. Several large groups of claims, covering the most of the manganese-bearing ground, wore assembled in 1929 and 1930. The greater part of this area was leased by the M. A. Hanna Co. in 1937. Investigations by engineers and geologists for this company revealed that the average content of manganese is very low; but that the Maggio Canyon area, about 180 acres, contains higher-grade material. The company put down 28 vertical diamond-drill holds to explore this ground, under the direction of B. N. Wobbor, geologist.

Jan 1, 1948