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By Peter Wells, Laxman M. Amaratuga, Todd M. Kanhai

"Certain mining methods (eg. Cut-and-fill) result in the contamination of run-of-mine ore with shotcrete. This shotcrete remains mixed with the ore throughout processing. Experimentation performed by Falconbridge Limited revealed that underground contamination of ore by shotcrete (eg. as little as 1% by weight) has led to ill-effects on the nickel recoveries from the flotation process in the mill. The nickel recoveries of contaminated samples were lower than tests without the shotcrete Contamination.To optimize flotation circuits it is important to know why the contamination has created these effects and also to find a method to abate or remove them. Laboratory testing showed that the age of the shotcrete was a factor in it’s effect on nickel recoveries. Younger aged shotcrete gave nickel recoveries lower than baseline nickel recoveries with no contamination. Older shotcrete gave nickel recoveries similar to the baseline.Literature on other cementitious material contaminations on ore revealed that a possible means of remediating this problem is the use of acid in the flotation. The initial pH in the flotation pulp was designed to be pH 9.2, but with the young shotcrete contamination the pH was in the neighbourhood of 10.5. Acid addition may act as a means of lowering the pH to the optimal operational value. Laboratory test work showed that acid addition brought nickel recoveries closer to the baseline."

Jan 1, 2000

By P Corbett, P Sheffield

Springvale Mine is an underground coal mine in the western coalfield of New South Wales which utilises retreat longwall mining technique. The mine encountered significant gateroad floor heave issues during retreat of LW415. Floor heave has subsequently impeded longwall advance as well as longwall bolt up and recovery to some extent during the extraction of the next five longwalls. Floor heave at Springvale Mine develops throughout the lifecycle of the mine roadways, and is most prevalent in longwall gateroads. Floor heave has been measured as early as 2 weeks after roadway development and continues to develop through the post-development phase, with a rapid increase in close proximity to the longwall face. This paper presents a case study of the evolution of understanding of floor heave behaviour at Springvale Mine based on geotechnical characterisation, an intensive convergence monitoring program (roof and floor movement) and spatial correlation of monitored locations with longwall face position. The analysis considers previously known factors contributing to floor heave including mining depth, geological and physical properties of the rock mass and mine design geometry. Investigation results indicate a strong correlation between floor heave magnitude and roof dilation magnitude, geophysically inferred faulting in underlying strata, areas of localised stress concentration and mine roadway dimensions. This paper also discusses the predictive model which was developed as a result of the study, which is now the basis of the floor heave removal program used to manage roadway convergence at the mine. Floor heave monitoring, prediction and management strategies (including floor reinforcement and removal) are also discussed. CITATION:Sheffield, P and Corbett, P, 2018. Managing floor heave in an underground longwall coal mine, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 78–94 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By C Reed

Titaniferous magnetite deposits are a significant source of vanadium for use in high strength steel alloying and other chemical applications. The mineralogy of the deposits varies markedly and the ore characteristics strongly influence the process route selected and the metallurgical outcomes. Characterisation of the ores reveals the presence of magnetite, ilmenite and other minerals such as spinel hematite and goethite with variable degrees of weathering along with weathered products of host rock. The standard processing route is to crush, grind and magnetically recover a concentrate for salt roasting to produce a soluble vanadate. Ore beneficiation is practised to generate an iron based mineral concentrate containing much of the vanadium with low silica levels of two per cent. Typical processing problems encountered are fine liberation size, over grinding of the magnetite and variable response to magnetic separation resulting from the weathering profile. Beneficiation options are restricted, and generally focused on producing a combined iron and titanium rich concentrate containing vanadium due to the fact that ilmenite and magnetite and their products of weathering are magnetic and have similar specific gravities making their separation difficult. The ilmenite usually contains low levels of vanadium making its separation highly desirable from the iron mineralisation containing higher levels of vanadium. Salt roasting of vanadium ores followed by water leaching has been the standard processing route for many years. The cost of suitable sodium salts, availability of capital and increasing energy costs and energy availability are critical factors in determining the viability of aspiring vanadium producers. To date, only Windimurra has acquired full capital funding, secured energy and sodium salt supplies at suitable cost that enable the construction of the project. Low overall recoveries of vanadium to concentrate roasting at up to 1200¦C are critical cost issues. In this paper, factors influencing the recovery of vanadium are reviewed and emerging processing trends explored. The important features of the processing of titaniferous magnetites have been condensed from the literature, published works, company websites, our own work and personal communication.

Jan 1, 2008

By Stefan K. Schwank

The paper describes the two foundation techniques - mini piles and postgrouted bored piles. The mini pile system is presented with its design and installation parameters, especially the drilling technique. Two case histories demonstrate the application under extremely limited space and traffic conditions and the required modifications of the equipment. After the description of the postgrouted bored piles and its grouting technique, the paper gives a comparison of postgrouted piles and standard piles on a large basic test in Germany. The Brooklyn Queen's Expressway, N.Y., case history shows the application of this technique after redesign of the original proposal. 1. General Increasing requirements to improve existing foundations to carry additional loads and to increase the bearing capacity of bored piles leads to two new piling techniques: the mini-pile and the post grouted bored pile.

Jan 1, 1991

By L. Wilfley, G. A. Calboreanu

"Wear resistant 25% Cr hard cast iron is a heterogeneous material containing 1,600 HV hard chromium carbides embedded into martensitic matrix. It is the most used cast alloy in wear operations of mining industry, chemical industry, fracking, etc. During the last decade the hard iron manufacturers increased wear resistance in the following ways: • Reduce / eliminate harmful retained austenite and chromium + carbon depleted areas especially within eutectic carbide cells. In Max5A the improved 25% Cr alloy brittle carbide eutectic cells are removed which increases toughness. • Delay delamination between chromium carbides and matrix particularly during sliding abrasion wear. Delamination commences at the weakest chromium carbide – matrix contact lines exposing chromium carbide to localized bending stresses which gradually chip carbides away. Once the chromium carbide base is removed accelerated wear degradation occurs. • Evenly randomize and avoid discontinuities in the chromium carbide network. When chromium carbides are perpendicularly positioned to the wear surface wear rate is minimized. On the contrary the highest wear rate takes place when 3D oriented chromium carbides are parallel with the wear surface. In this case chromium carbides cover top network discontinuities being just matrix supported which leads to rapid carbide cracking. The new hard iron discussed in this paper fulfils and exceeds the above requirements increasing the casting service life around 250% in various wear operations. Physical and mechanical properties of Max5A are compared with well manufactured Industry Standard 25% Cr hard iron. The paper presents practical accomplishments obtained in the USA, South America and India. INTRODUCTION The chemical composition of Max5A and Industry Standard 25% Cr are identical like specified by ASTM A532 Class III Type A requesting C = 2.0-3.3% and Cr = 23.0-30.0%. Manganese, silicon, nickel, molybdenum and copper contents are limited by maximum accepted quantities.[1] According to published data the eutectic chromium carbides chemical composition of 25% Cr hard iron is Cr = 54% and C = 8% which indicates strong depletion of chromium and carbon along chromium carbide - matrix interfaces. [2] The optimized Max5A microstructure has minimized retained austenite, is devoid of harmful carbide eutectic cells and has the most advantageous chromium carbide and secondary chromium carbide morphology. This favorable microstructure increases wear resistance, mechanical properties and corrosion resistance. The paper compares the Max5A microscopic features and mechanical – physical properties with similar properties of high quality Industry Standard 25% Cr."

Jan 1, 2017

By James J. Scott

Friction Rock Stabilizers, trade name II Sp 1 it Sets'" have been under research and development by the author and the Ingersoll-Rand Company since February of 1973. The United States Bureau of Mines and the Mines Enforcement and Safety Administration as well as many mining companies have cooperated in field testing the device. Split Set rock anchors are distinctively different from the widely used mechanical rock anchors or fully grouted rock anchors. They control ground movement internally in a manner that allows controlled deformation during the early phase of the ground reaction curve but then, as secondary creep develops, anchorage per unit length increases and they serve to strengthen and stabilize the opening for long periods of time. The history of research and development of the Scott Split Set rock anchor system with accompanying laboratory and field test data is presented in this paper.

Jan 1, 1977

By S. Kok, D. Delport, J. Calitz

Altering the microstructure in order to improve the tensile properties of bow shackles resulted in inconsistency in the fatigue performance. This raises the question whether the inconsistency in fatigue life can be attributed to microstructural changes along the profile of the shackle or to decarburization at the surface. Bow shackles forged from 080M40 (EN8) material were subjected to different heat treatments in order to alter the microstructure. The shackles were subjected to five different fatigue load cases, which represented typical loads experienced at termination points for an overhead power line with a span length of 400 m, with changes in conductor type, configuration, wind, and ice loading. Although the change in microstructure does improve both the tensile and fatigue performance, we found that the depth of the decarburization layer has a greater effect on the high cycle fatigue life of bow shackles than the non-homogeneous microstructure.

Oct 1, 2021

By R. W. Heins, N. Street

An investigation was made of the Rehbinder-Kuznetsov pendulum as an instrument to aid in the study of rock drillability and of the effect of surface active agents on rock drillability. The "critical weight", i.e., the pendulum weight at greatest sensitivity, was determined for several solids and it was shown that a change in surface environment changed the maximum value of the apparent hardness but not the critical weight, and the critical weight increased with increase of hardness of the solid used. Using silver halides as the solid material, and solutions of either silver nitrate or the appropriate alkali halide, it was shown that there is a hardness maximum at the zero point of charge of the particular silver halide. INTRODUCTION The development of relative hardness measurement by the method of damped oscillations, or what has been called the pendulum sclerometer, is due largely to the Russian workers P. A. Rehbinder and V. D. Kuznetsov and their co-workers.1,2 The apparent simplicity of the method has led to its use in a number of fields, particularly those where relative hardness has to be determined on a brittle solid. As will be shown, the simplicity of the method belies its complexities. THEORY OF THE PENDULUM SCLEROMETER The operation of the pendulum is quite simple. Make a sharp point such as a diamond, hardened steel or tungsten carbide, as the fulcrum of a pendulum, with the center of gravity of the system below the point of support. The attenuation of this pendulum is a function only of air friction, provided no fragmentation, breakage or other work is performed by the point. However, when the solid surface breaks or disintegrates under the point, and the latter penetrates the solid, part of the energy of oscillation is absorbed in the work of creating new surface, and the rate of attenuation increases. In the case of brittle solids, the point of the pendulum produces fragmentary particles, whereas the point produces plastic deformation in a plastic solid; but in both cases damping occurs. This pendulum damping is a function of the hardness or strength of the solid. Whereas a pendulum oscillating on a hard material attenuates primarily by air friction, in the case of a soft material, the points penetrate the surface of the solid, producing new surface, and the pendulum damps much faster. Thus the attenuation rate is a function of the hardness or strength of a material in both plastic and brittle substances. Russian workers initially used a single support for the pendulum, but this created many problems because of oscillation of the pendulum in more than one plane. A revised version used two points, or sometimes a prism as support, successfully confining oscillation to one plane. The version using two points was constructed and used throughout this investigation, making the recording of the attenuation as a function of time relatively easy. That both points should be in contact with the solid during the damping is implied. Rehbinder (c.f. Kuznetsov2) proposed that the hardness H as measured by this method could be expressed by a quantity which is inversely proportional to the relative initial rate of attenuation of amplitude. where H = hardness parameter (arbitrary units) a, = initial amplitude da/dt = rate of attenuation of amplitude with time. In the simplest case of damping with a constant logarithmic decrement, H can be regarded as a constant for the duration of the whole damped oscillation process. That is

Jan 1, 1966

By F. A. Patty

[Health and safety hazards from contamination of the atmosphere in places frequented by persons depend to a considerable extent on whether the contaminating agent possesses sense-perceptive properties which will give warning of its presence before it '.an create harmful conditions. If a distinct and easily recognized warning is given in advance of harmful conditions, hazards ace mitigated, but if warning properties are inadequate or absent, the hazards are augmented. When evaluating the hazard presented by a potentially harmful substance used under conditions of possible escape into the air of places frequented by persons, it is therefore necessary to consider the warning properties of the substance along with ether pertinent information such as toxicity, inflammability, physical properties, and mode of use. If the contaminating agent inherently lacks warning; properties it may be possible to impart them by adding to the hazardous substance a small quantity of a relatively harmless substance which has a high warning intensity.]

Jan 1, 1929

By Timothy P. Smirnoff, Tracy K. Lundin

INTRODUCTION The City of Phoenix, Arizona is located in the Phoenix Basin watershed which is prone to flash flooding several times each year. The runoff from these storms moves from the mountains in the north to the Salt River in the south. An extension of Interstate Highway 10 (1-10) will pass through the city east to west to form an Inner Loop through the downtown business district. PROJECT DESCRIPTION The I-10 Inner Loop extension will be a depressed roadway which would intercept the surface drainage of the Phoenix Basin and separate the watershed into two regions. To prevent flooding of the depressed roadway, runoff storm water collected from the northern half of the drainage area will be conveyed beneath the roadway to its natural outlet at the Salt River. A conveyance system composed of pressure tunnels beneath the city, shown in Figure 1, was proposed to achieve this goal . Table A presents the prominent features of each of the tunnels. This paper will describe geologic and engineering parameters specific to Phoenix which were used in the design of a series of tunnels to convey storm water from the I-10 Inner Loop to the Salt River. The design of tunnel initial and final support is described along with support and construction methods used by the Contractor.

Jan 1, 1985

By Wilbur I. Duvall, Thomas C. Atchison, Joseph M. Pugliese

Short cylindrical charges were detonated in drill holes in rock to determine the effect that decoupling ( defined as the ratio of the radius of the hole to the radius of the charge ) has on the strain - generating abilities of explosions in rock . The amplitude and period of the strain pulses produced in the rock were studied as a function of distance , size of charge , and decoupling . The main results of these studies were that , for a given distance and size of charge , the amplitude of the strain pulse decreases as decoupling increases and the period of the strain pulse decreases at first and then increases as decoupling increases . A simplified theory of decoupling is presented that satisfactorily explains the experimental results . The information presented makes it possible to predict the effect of decoupling on explosiongenerated strain pulses in rock and thus helps the explosives user evaluate the effect of decoupling on his blasting .

Jan 1, 1964

By J. W. Paul

[A study of mining methods and underground practices as they influence injury from falls of roof or coal reveals data as to the location in the mine where such injuries occur with the greatest frequency and as to some of the methods and practices which are in use for the prevention of injury. This paper, which presents statistics bearing on the frequency and place of occurrence of accidents and, discusses regulations and practices which have resulted in a low frequency rate from falls of roof and coal in a few representative mines takes its information from mine-accident reports and from the results of studies conducted in a group of 80 mines in the bituminous coal fields of western Pennsylvania, Ohio, and West Virginia. The statistics from this group of mines cover periods of one to four years but average 2 years and 7 months. During this time these mines produced over 110,400,000 tons of coal, equivalent to one-fifth of the annual production of all bituminous mines in the United States. The coal beds of the mines in the group studied are mostly flat, with local pitches of moderate degree. A number of mining plans are in use, each of which follows a general system of multiple entries, cross entries, and rooms. Room and pillar in panels either advancing, retreating, or half advance and half retreat and the block systems are employed. The methods of pillar extraction are by splitting, slabbing, pocket-and-stump, and open end. It is hoped that in presenting some of the details of the methods and practices at particular mines of this group which have commendable records in the prevention of injury some good may accrue to many other bituminous mines which 'nave similar natural conditions.]

Jan 1, 1933

By J. Bruce Gemmell

ODP Leg 158 drilled seventeen holes into the active TAG hydrothermal mound and underlying stockwork, 26°N, Mid-Atlantic Ridge. Drilling in five different areas, including a high-temperature black smoker complex and a lower-temperature white smoker vent field, revealed the multi-stage depositional history and character of sub-seafloor mineralization and alteration. The upper portion of the mound consist of massive pyrite and pyrite breccias which are underlain by pyrite-anhydrite breccias and then by quartz-pyrite breccias. Quartz-pyrite breccias grade down into silicified wallrock breccias. Chloritised basalt breccias occur at depths greater than 100 m. Several stages of quartz-pyrite±chalcopyrite veins occur in the stockwork zone and lower portions of the mound, whereas anhydrite±pyrite±chalcopyrite veins occur within the upper parts of the mound. Recovery of unaltered basalt near the edges of the mound has constrained the extent of the stockwork zone to a pipe-like feature 80 meters in diameter. A detailed sulfur isotope investigation of sulfides and sulfates within mound and the underlying stockwork zone has revealed the overall range of sulfide d34S analyses to be 0.35% to 10.27%. Anhydrite has a tight range of d34S values 20.55% to 21.56%. There are distinct differences in d34S values between the different textural types of pyrite (massive sulfide, breccia clasts, disseminations associated with alteration, and veins). The massive sulfide and breccia clasts have a similar distribution of d34S values (6%-8%), however the d34S values of the disseminated pyrite associated with the alteration are distinctly heavier (8%-10%). Vein sulfides have the lightest d34S values (5%-7%). Sulphur-isotope values at TAG are, in general, the heaviest reported for unsedimented mid-ocean ridge deposits.

Jan 1, 1998

By E. C. W. Perryman

The recovery of X-ray line broadening, hardness, and electrical resistivity from cold worked AI-Mg alloys has been investigated. The results, together with those from density measurements, suggest that magnesium atoms freeze in the excess vacancies formed by cold working, and that this affects the climb of dislocations during the recovery process. PREVIOUS work1, " has shown that while 1 pct Mg increases the activation energy for recrystalliza-tion, it decreases the activation energy for the recovery of mechanical properties and decreases the subgrain size both after cold working and annealing. A similar result has been reported by Varley2 for an A1-2 pct Mg alloy. With plastic deformation at high temperatures, McLean and Farmer' and Rachinger have found that magnesium appears to retard the motion of dislocations and, furthermore, they find little or no effect of magnesium on the size of subgrains formed during high temperature deformation. In view of the apparent contradictions as to the effect of magnesium on subgrain size, the recovery process in Al-Mg alloys has been investigated more thoroughly by studying the annealing out of X-ray line broadening, hardness, and electrical resistivity from alloys cold worked at room temperature. Material Used—The chemical analyses of the alloys are given in Table I. Fabrication—The material used was cold rolled 20 pct at room temperature, the grain size prior to the last cold rolling operation being similar to that used in previous work; i.e., 230. The experimental procedure for annealing, determination of X-rav half-veak breadth. hardness measurement, electEica1 resistivity, and density and metallographic examination was exactly the same as previously described." Variation of X-Ray Half-Peak Breadth with Annealing Time—Isothermal annealing curves at 100°, 200°, and 250°C were obtained for material cold worked 20 pct. The half-peak breadth of the (333) Ka, line directly after cold working is shown as a function of magnesium content in Fig. 1. Only with the 2.87 pct Mg alloy was overlapping of the a, and n.. reflections observed to any appreciable extent. To separate these, Rachinger's method' was used. Typical isothermal annealing curves are shown in Figs. 2 and 3 for 100" and 200°C, respectively. These curves are similar to those obtained previously for super-purity aluminum except that the

Jan 1, 1957

By R Hao

Uncertainties in large open pit geotechnical modelling has been a major concern for slope stability analysis. The level of confidence in the in-put assumptions, such as structural and rock mass model, dictates the modelling results to some extent. This article is to detail a case study of Kalgoorlie Consolidated Gold Mines (KCGM) regarding a predicted inter-ramp failure on an as-built pit walls by a 3D numerical modelling. Significant concerns were raised across site and multiple preventive plans were considered. After intense data collection work, it was confirmed that the risk of failure had been overestimated. The case study has improved the understanding of geotechnical data in-put and has enhanced the process of creating and updating geotechnical structural models at KCGM.

Jun 22, 2022

By Katie Schumacher, Greg Roset, Dayle Flynn

The Columbus Processing Complex of the Stillwater Mining Company began operations at Columbus, Montana in 1990 based on electric furnace smelting treating a precious metals concentrate from the nearby Stillwater mine and mill. Since that time, the smelter plant has been expanded in stages in order to treat recycled materials in addition to the concentrate. This paper describes a number of changes made at the plant to effectively handle recycled materials.

Jan 1, 2014

By A. Koning, P. Lauzon

Pressure hydrometallurgy operations require vessels to be lined with an impermeable membrane for corrosion protection and one or more courses of refractory or ceramic brick. Examples of unit operations that utilize composite lining systems include pressure oxidation autoclaves, sulphide precipitation autoclaves, chloride leach reactors, flash vessels, cyclone separators, and direct contact condensers (heater vessels and quench vessels). The refractory lining must satisfy multiple requirements: it must thermally insulate the membrane from process fluid, be structurally stable, provide erosion resistance, be chemically compatible with process fluid, and provide an economic service life. New hydrometallurgical processes are pushing the pressure, and temperature, with each new generation of plants. A fundamental understanding of all factors affecting the mechanical stability of the lining system is essential as lining designs move further away from the industry's experience base. The impact of irreversible chemical swell, operating factors, design factors, and installation factors are presented based on modifications to the traditional one-dimensional mechanical stress model. A new stability criterion - that the brick lining remain in contact with the steel shell membrane - is presented. This new stability criterion imposes new restrictions on the lining design.The effect of geometry and adding additional degrees of freedom to the analysis is explored using two-dimensional and three-dimensional Finite Element Analysis (FEA). The effect of these additional degrees of freedom on the results of the one-dimensional model are discussed.

Jan 1, 2004

By C. Vipulanandan

With the aging infrastructure, there is a need to maintain and extend the service life of steel structures in general and steel piles in particular. Steel piles support not only vertical loads but also dynamic horizontal loads in onshore and offshore applications. In order to select the appropriate methods to repair corroded steel piles used in onshore and offshore application, corrosion mechanisms were investigated with the rate of corrosion in various environments. The corrosion rate of steel in soil, water and soil-water interface varied from 2 to 500 µm/year. Based on literature review and analyses, the repair methods can be broadly characterized as protective coating, electro-chemical methods, wrapping and encasement and partial replacement of steel. Also, methods to evaluate the repair materials and the repair configuration have been documented.

By John R. Troxell

"INTRODUCTION The Ahles iron mine, also known as the Pequest mine, in Warren County, N. J., was operated continuously for 15 years and was still in ore when it closed in 1916.Tie property was examined by an engineer of the Bureau of Mines in March 1943. 3/ This examination led to an investigation of the deposits by the Bureau by diamond drilling two holes under the old workings to determine whether the extends downward.This report describes the work done at the Ahles mine by the Bureau and presents the data obtained.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. The Mining Division, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual investigative work, and prepares the final report.The Metallurgical Division, O. C. Ralston, chief, analyzes samples and performs beneficiation tests.The investigation was under the general supervision of J. B. Zadra, acting regional engineer, and under the immediate supervision of G. D. Jermain, district engineer for the States of Pennsylvania, New Jersey, Maryland, and Delaware. The author was in direct charge of the project.The chemical analyses for the project were performed at the College, Park, Md., laboratories of the Bureau of Mines under the direction of M. S. Sheftel. The ore-dressing tests were conducted at College Park under the direction of Frank Lamb. Preston E. Hotz, of the Federal Geological Survey, logged and interpreted the drill cores."

Apr 1, 1948

By Bidwell TJ, Servant S

Paste back-fill technology is gaining rapid acceptance in the Canadian mining industry. The authors were able to work on four different mining sites employing paste technology in their operation. In each site the paste hackfll is prepared with very fine tailings containing significant amounts of sulphur minerals. The research program involved laboratory testing on samples prepared in the laboratory, on control samples obtained at the hackfilll plant during pouring into the stopes and on core samples obtained from drilling in backfilled stopes. The laboratory testing provided detailed knowledge of the mechanical behavior of the paste backfill. The need for a means of measuring the in-situ mechanical properties of the backfill became clear. A review of various trials published in literature and an evaluation of available technology suggested the Cambridge Self-boring Pressuremeter. A first field campaign confirmed the efficiency and dependability of this instrument leading to the conclusion that it offers a very good method for the in-situ measurement of paste backfill properties.

Jan 1, 1998