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By S. Middlemiss

The Indentation Fracture technique is being developed as a tool for use in comminution and mineral liberation analysis. Fracture toughness measurements for a number of mineralogical materials were made and comparisons were drawn between these and properties measured with the Ultrafast Load Cell drop weight apparatus. The technique has also been used as a probe to quantify differences in fracture properties at different areas in the microstructure of a material. In both a Utah limestone and a South African quartzite, material near a grain boundary fractures very differently to that in the bulk. Ongoing work is ultimately aimed at producing a comprehensive fracture model for a multi-mineral system based on its micro-fracture characteristics.

Jan 1, 1994

By A. A. Densmore

Telluric Current is that portion of the electric field observed at the surface of the earth which is of an alternating nature, and which is related to solar activity and events in the ionosphere. The primary electromotance which drives the telluric current is the result of the induction process associated with time variations in the earth's magnetic field. The relationship between the electric and magnetic components of this electromagnetic field depend upon the conductor. For our purposes, we are dealing with frequencies f in the range

Jan 1, 1972

By Y. Guo, C. Cao

"China is rich in tungsten resource, but they are mainly associated minerals. The similar flotability of scheelite, fluorite, and calcite resulted in the difficult separation by flotation. This work summarized the current situation and the development of flotation reagents, technological process, and mineral processing equipments in China. Fatty acid served as the collector and water glass was the depressant to expand the flotability differences in traditional flotation technology. However the water glass inevitably influenced the flotation of tungsten minerals to a large extend, and the suppressed fluorite was difficult to recover by flotation. Abundant water glass lead to the bad settleability of the tailings and the tail water was difficult to circulate, resulted in serious environmental problems. Recent study proved that the selectivity of benzene armour hydroxyl oxime acid (BAHA) salts was adequate for the separation of tungsten minerals from fluorite, calcite and most silicate minerals without any depressant. By this way, sodium silicate was canceled completely in tungsten flotation, greatly improving the recovery of tungsten and the environmental problems caused by tail water treatment would be solved fundamentally. TUNGSTEN RESOURCES AND DISTRIBUTION IN CHINA China is rich in tungsten resources and the proved reserves accounted for 60% of the world's reserves [1]. However the wolframite has been dried up and the scheelite resources had become the main resource of the tungsten metal. Table 1 showed the most large and superlarge scheelite deposits in China. China has more than 40 large and superlarge scheelite deposits and the total metallic deserves is more than 3 million ton [2]. But most of the deposits were low-grade and the associated relationship was complicated. For example, scheelite was usually associated with wolframite, molybonite, bismuthinite, pyrite, fluorite, and calcite in Shizhuyuan and Yaogangxian mine."

Jan 1, 2016

By M. Paventi, M. J. Scoble, B. B. Mohanty

There is no straightforward and systematic method for adequately measuring blast damage in on-going mining operations. This paper considers various techniques available for the measurement of blast damage, making particular reference to recent underground hardrock mine studies. This paper concludes by indicating the importance of understanding and accounting for geology and emphasizes the need for a robust damage-audit procedure.

Jan 1, 1998

By Emily Adelsohn, Robert Winn, Anthony Iannacchione

"Over 600 longwall panels have been mined in Pennsylvania in the last 50 years. Of those 600 panels, 25 panels undermined interstate highways. Despite this quantity of panels, much is still unknown regarding the detailed effects of undermining highways. The Gateway Mine, the Emerald Mine, and the Cumberland Mine undermined I-79 with 17 panels between 1982–1989 and 2003–2008, respectively; mine Eighty-Four undermined I-70 with 4 panels between 1987–2000.Through the examination of the panels that undermined I-70 and I-79, it is possible to determine which factors have most impacted the highway alignments. In some locations, the highway intersects with panels at angles ranging from 45 to 80 degrees, and at others, it runs between two panels, which simulates the effect of gateroads on the subsidence. The panels width to overburden ratio varies between 0.64 and 1.7, meaning that the interstates were influenced by both subcritical and supercritical subsidence basins. The face advance rates and overburden depths also vary between the panels.Unfortunately, specific information detailing highway impacts associated with unique characteristics of the subsidence basins are limited. However, using the profile function model and influence function model within the Surface Deformation Prediction System (SDPS), the effects of overburden, panel size, and orientation of the road to highway can be indirectly assessed by profile and influence models of subsidence basin formation.INTRODUCTIONCoal mining has been an integral part of Pennsylvania’s history. Room-and-pillar mines have been active since the late-1700s when coal was extracted from outcrops. By 1830, the city of Pittsburgh alone consumed more than 400 tons of bituminous coal each day for domestic and industrial use (PADEP, 2019). In the late 1960s, the face of mining in Pennsylvania changed with the development of full extraction longwall mines. Since that development, over 600 longwall panels have been mined in the Pittsburgh Coalbed in Pennsylvania alone (PADEP, 2019).As longwall mining and other forms of full extraction mining have increased in popularity, the amount of planned subsidence impacting the surface has also increased. The stresses and strains induced by longwall subsidence can cause damage to the surface as well any structures, water supplies, or water bodies that lie above the panel. Since the behavior of soils and structures vary, one way to study the surface effects of longwall mining is to analyze the impact on flat, rigid, pavement surfaces. Examining factors that vary the impact of subsidence with respect to highway alignment can demonstrate the favorable orientation of an alignment to avoid or mitigate damage and critical impact zones in a subsidence basin."

Jan 1, 2019

Industry and regulatory agencies have requested guidance on safe blasting near transmission pipelines. The U.S. Bureau of Mines and AMAX Coal Company have studied surface coal mine overburden blasting near four steel and one PVC pipe-line of 15 to 5l-cm diameter, monitoring vibration, strain, and pressure. Unlike tests simulating construction blasting, these were up to 1000 kg per delay in 3l-cm blastholes. Worst case comparisons showed that 12.7 cm/s blasting vibrations produced strains about 1/4 that of pressurization and 10-18 pct of the ultimate tensile strength. No failures occurred from blasting as close as 15 m which produced vibrations over 60 cm/s.

Jan 1, 1994

By D. R. McMullin

The purpose of this paper is to provide a method for mine planners and engineers to evaluate on a conceptual basis if a shaft or a ramp is most suited for their particular underground access requirements. Mine planners and engineers are often raced with the decision of choosing which method of underground access is best suited for their particular requirement. Underground access can be provided by a shaft, ramp, adit, or slope for either exploration and/or actual production operations. This paper will focus on the construction cost and schedule differences between sinking a shaft and excavating a ramp which are currently the most typical access alternatives used in the western United States. It would be wrong to state that one method is superior to the other in every case. There are many variables to be addressed, and the degree of sensitivity of each of them will eventually dictate which method is the most suited to the particular circumstances. This paper compares the construction cost and schedule or sinking a shaft to excavating a ramp at different depths given different ground and hydrological conditions. This comparison provides mine planners with "rules or thumb" that may be applied to the access selection process.

Jan 1, 1994

By G. A. Calboreanu

The deterioration rate of any metal or alloy is increased in a erosion-corrosion application because the passivated surface layer is removed by the solid particles contained in the pumping fluid and the material surface becomes corrosion active again. Numerous attempts were made to engineer a stainless steel with higher hardness and unaffected corrosion performance. Alloys of special interest in such an area are the duplex stainless steels particularly the CD4MCu material which has the capability of being hardened due to its ferrite-austenite microstructure. Unfortunately, the CD4MCu with higher hardness comprises different intermetallic compounds which will increase the corrosion rate. The paper is analyzing the erosion-corrosion performance of a new type CD4MCu with 32% higher hardness and superior wear performance. The corrosion performance of this new alloy is better than the corrosion performance of the common CD4MCu material which the industry could supply. The corrosion effectiveness was evaluated with the Huey test, the potentio-dynamic anodic polarization test and the weight loss test whereas the erosion resistance was established with a low stress ball-on-disk type apparatus. The Wilfley hard CD4MCu material had 39% lower weight loss and 32% smaller volume loss than the common CD4MCu alloy The hardness range of the centrifugal pump parts poured and processed with the Wilfley hard CD4MCu is 320-350 HBN versus 250-255 HBN hardness of the common CD4MCu. After approximately 18 months of experimentation and field testing it was clearly established that the life time of the Wilfley hard CD4MCu is higher than the common CD4MCu and consequently centrifugal pumps were supplied to different customers in North and South America. India and more recently Australia. Sincere thanks to all the A.R. Wlifley & Sons Inc. and Western Foundries Inc. employees who supported and help to implement this work. special thanks to George Wilfley. Dave Cobb. Bill Becker Sr. and Wayne Taylor

Jan 1, 1997

The paper describes a practical methodology based on numerical modelling for the prediction of progressive failure of underground mine stopes with cable bolt support. A case study of the 40-761 stope at Kidd Creek Mine, Timmins, Ontario is presented. The stope was mined by blasthole open stoping in 1986 as a lead stope within a mining block between 36-1 and 38-2 levels. Initially designed to peak at 38-2 level, the stope back caved upwards approximately 40m towards 36-1 level. Cable bolts were installed above the stope from 36-1 level after caving had begun. The stope eventually stopped to cave when the falling rock mass encountered a sufficiently high cable density. The paper provides details of the geomechanical data and modelling results of the case study. Numerical modelling is carried out using a finite element package known as e-z tools which has, among other things, a special cable/rockbolt simulation capability.

Jan 1, 1994

Interstate 70 running into the mountains west of Denver, CO is the main access to the state?s numerous ski areas and other tourist attractions. As such, the highway is a vital part of Colorado?s economy. Due to the mountainous terrain in which it winds, I-70 is limited to two lanes in either direction. And, during the past few decades, the volume of traffic has increased to the point where motorists encounter major delays, particularly on Friday evenings and Saturday mornings heading west from Denver, and then again on Sunday evenings heading east. In the past, those delays occurred mostly during the ski season. However, many of the mountain towns have been successful in turning their resorts into year-round vacation destinations. A good move economically, but the pressure added to I-70 has caused even greater traffic delays, sometimes to the point where some Front Range residents avoid trips to the mountains.

Jan 1, 2013

By Peter F. Howard

The lower Middle Cambrian phosphorite deposits of the Georgina Basin shown in Figure 1 were found in the period 1966-1968 by three companies, namely, International Minerals and Chemical Corporation, Continental Oil Corporation and Broken Hill South Limited. Of these deposits the significant ones are Duchess, Sherrin Creek, D Tree, Lady Annie, Lady Jane, and Wonarah which together aggregate several billion tons reserves of phosphate. Due to the economic factors of freight costs to the coast and softening of the world market price for rock phosphate, none of them is in production, nor is any in the development stage. This paper reviews the historical background to the discovery of these deposits and then deals principally with the discovery of non-outcropping phosphorites in the Barkly Tablelands of Northern Territory by the interpretation of gamma radiation logs of abandoned water bores.

Jan 1, 1971

By Donald E. Zipperian

It has been recognized that froth flotation of mineral particles utilizing rising flow of micro size air bubbles, counter-current to quiescent falling flow of particles in a column type cell, provides a unique mechanical atmosphere conducive to extension of froth flotation process to much coarser and finer particles sizes than possible with mechanically agitated and aerated cells. 1,2,3,4. This paper describes metallurgical results obtained at several plant installations of large capacity commercial size Deister FLOTAIRE® Column Flotation Cells. These cells utilize air aspiration into surface tension lowered water to generate micro size bubbles. Operating costs, power, wear, and scaling characteristics of rougher, cleaner, and scavenger units are compared with mechanical units. Problems encountered and scale up criteria developed when increasing from 0.20m(8inch) diameter pilot cells to 2.42m(96inch) commercial cells are discussed.

Jan 1, 1985

By T. S. Golosinski

This paper identifies the components of belt conveyor shifting force as a vertical force. Pv, horizontal force, Ph, and longitudinal force, P1. A method for estimation of these forces is proposed, which relates their value to the properties of the conveyor structure and rails, shifting operation parameters, and other site-specific conditions. The effect of this force on shifter behaviour is analysed and guidelines are developed for selection of a suitable shifter. Also discussed are the requirements of the shifting operation for other equipment.

Jan 1, 1986

Over the years, numerous studies have been conducted to characterize the floatability of coal pyrite. Unfortunately, many of the results obtained using isolated samples of coal pyrite are not directly applicable to actual coal flotation systems where liberation and entrainment may be the major factors affecting pyrite rejection. In this paper, the association of pyrite with other coal constituents is investigated, and the data are presented for feed and product streams obtained from release analysis tests. Release analysis is used to minimize the effects of entrainment. Particle distributions for each stream are presented as functions of size and composition in order to discern the behavior of free and composite particles.

Jan 1, 1992

By Lloyd E. Haight

After accepting the invitation to make this appearance today, it occurred to me that the subject matter which had been assigned to me, namely, the purpose and role of an advisor, was, contrary to what; some people might think, a controversial subject. In my brief lifetime, I have discovered that the world is full of advisors; that is to say, there are many people who undertake to render advice concerning subject matters upon which they may, or may not be qualified to speak. It shall be my purpose today to set forth what now appears to be the function of the members of the Advisory Council to the U. S. Public Land Law Review Commission; and, in so doing, I hope that I do not offend the Commission or any other-member of the Advisory Council with whom I serve. It has always been my personal conception of the role of an advisor that he should tender advice when it is requested, and then only if he has prepared himself concerning the matter upon which the advice is being given. I am sure it was the Congressional intent at the time the Public Land Law Review Commission was established indeed it was the hope. of Congress--that those of us who were to become members of the Advisory Council were informed upon certain particular subjects and then at the proper time express our opinions upon these subjects-and, by the same token, not attempt to enter opinions upon problems with which we have no experience in theory or in actuality. Some wag once said that if Columbus had had an advisory council, he would still be waiting at the dock in Spain, and there is more truth than fiction in that statement. With this problem in mind, let us examine the purpose of the Advisory Council itself.

Jan 1, 1967

By F. Calizaya

This study summarizes the results of various numerical and laboratory experiments per-formed to study the effect of airflow recirculation on gas concentration. The numerical exercises were carried out on a simulated mine ventilation net-work. The laboratory experiments were conducted at the Mackay School of Mines' airflow monitoring system in Reno, Nevada. In both cases, the airflow was recirculated through the system by means of a main fan and a set of booster fans. The booster fans were positioned to produce two types of recirculation: In line and Cross-cut. For each type, various recirculation conditions were generated by changing the booster fan pressure. During each test, the gas emission rate at the simulated working face was kept constant. The study illustrates the conditions under which controlled airflow recirculation may be used to solve a district ventilation problem.

Jan 1, 1991

By Douglas B. Silver

Study Parameters (Status as of February 1993) Time Period: 1989 -1991 151 North American Public Metal Mining Companies Fiscal not calendar year basis 85+% of Canadian and U.S. Metal Production Au, Ag, Cu, Pb, Zn, Mo, Ni, W Results are Preliminary and Research Continues Chicken Little is Alive and Well

Jan 1, 1993

By Dennis Greene

Real-time GPS position monitoring of mining equipment is becoming more and more commonplace. Digital mining plans can now be used onboard properly equipped earthmoving equipment and excavation status is available in real-time via high bandwidth data radio systems. These systems provide a closely integrated link between operations and planning. No longer must operations wait for or be hindered by insufficient survey marks, nor is engineering delayed by lack of timely mine status information. Unprecedented efficiency gains become feasible -from the engineering office, to drilling and mucking, to reclamation, as well as in mine construction projects. Direct economic benefits of these systems will be explored as will the less tangible, but very significant, indirect operational efficiency gains.

Jan 1, 1998

By G. X. Wang

The nonliving dried water hyacinth (E. crassipes (Mart.) Solms) roots were investigated for biosorption of cadmium and lead and other heavy metal ions in aqueous solutions. Dried water hyacinth roots, when suspended in solution, strongly and rapidly sorb several different metal ions. Factors such as reaction time, pH, initial concentration of metal ions, presence of other metal ions and biomass concentration were investigated. Metal ions, including Cd2+ and Pb2+, were bound to the root in a very pH-dependent manner, with the binding increasing after about pH 3. High levels of removal were obtained. The adsorption was shown to follow the generalized Langmuir adsorption equation. The relative affinity of the roots for lead is greater than for cadmium. The maximum sorptions of the roots were about 33 and 86 mg/g for cadmium and lead, respectively. Only 15-20 minutes were required for the process of uptake onto the biomass to occur. The batch sorption kinetics of the uptake of cadmium and lead can be described by an apparent first-order reversible reaction model. The roots could be regenerated after the metal ions were stripped. A solution of CaCl2 in acidic medium appeared to be the best eluant for desorbing the sequestered Cd and Pb completely at pH 3. The kinetics of the metal stripping process was quite rapid. Successful desorption of Cd and Pb from the biomass by acidic CaCl2 solutions revealed that the metal uptake phenomenon is reversible, implying physical sorption of Cd and Pb.

Jan 1, 1997

By Martin H. Stanczyk

In recent, years the demand and consumption of finely ground industrial minerals has substantially increased for such uses as fillers and chemically reactive components. The size, specifications for these types of industrial mineral materials vary to a great extent and depend on the particular end purpose' and on the physical properties of the mineral itself. Size reduction of industrial minerals usually is obtained by conventional crushing and grinding methods. However, some specialized milling techniques have been developed for producing these minerals in extremely fine particle size ranges. During recent years the Bureau of Mines has been investigating an attrition grinding method to produce ultrafine subsieve-size mineral particles. The Bureau developed process, which has been patented,2 comprises the intense agitation of a slurry composed of the material to be ground, a relatively fine granular grinding medium, and a suspending fluid. The process has been shown to be effective for the comminution of kaolin in the particle size range of 2 microns and finer on a batch3 and continuous basis.4,5 This report presents the results of batch tests made to determine the effectiveness of the attrition grinding process for comminuting commercial products of (1) mica, a tough lamellar material, (2) fluorite, a brittle intermediately hard material, and (3) barite, a relatively soft, massive material.

Jan 1, 1967