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By P Khalkho, M Singh

Rock masses when subjected to uniaxial or triaxial cyclic loading (eg in hydraulic running tunnels, during retrieval and injection of oil and gas from storage underground caverns and haulage roads), the material has a tendency to fail in fatigue. In order to design safe and reliable underground structures, the determination of brittleness under such loading conditions becomes a pre-requisite. Brittleness influences strongly the failure process and makes the rock mass behaviour complex under different tunnelling and mining activities. Brittleness Index is a term to quantify the brittleness feature of a specimen. In the present study, an attempt has been made to quantify the brittleness of jointed specimens using different brittleness criteria. The joints of the model jointed specimens were oriented at an angle of θ=15° normal to the loading direction, each having three different JRC’s=2–4, 12–14 and 14–16. The specimens were tested under triaxial conditions in incremental complete cyclic test scheme performed at displacement-controlled mode. Different brittleness criteria were used ie stress-strain dependent brittleness index, Young Modulus approach and energy-balance based mechanism. It was observed that energy-balance based mechanism which consider the post failure behaviour is more descriptive to reflect the whole variation of brittleness from sheer brittleness to ductility.

Nov 29, 2022

By D. Caruso

The health and financial costs of cumulative injuries are plaguing the mining industry. Industry leaders are concentrating on reducing the risk of injury to their workers through design and redesign of work environments. While ergonomics is not a currently regulated field, many mines are realizing that the only way to tackle their most costly injuries, cumulative injuries, is to make the proactive choice to understand those injuries, their root causes and to make workplace changes to prevent them from occurring. Reduction of these injuries not only improves the health and morale of the workers but increases productivity and profit for the companies. Knowledge and reporting of ergonomic risk factors by employees and ergonomics committees is key to these changes and to the reduction of cumulative injuries. NIOSH is developing strong relationships with industry associations and equipment manufacturers to leverage their communication abilities to transfer knowledge to their customers and make a difference in the health and safety of U.S. miners. The benefits of a formalized approach to reducing these injuries along with examples will be presented.

By George C. Carter

It was just a little over three years ago that the "Go" button was pushed to start operations on the blending piles at Oro Grande. As is usual with any new installation, there were problems that had to be solved. This paper will concern itself with those problems directly related to quality control. To obtain a consistent outgoing quality level at the most economical level for a finished product requires two main points: 1. Measurement of variations in the process, 2. A method of making a predictable change to adjust for variations. The manufacture of cement requires a relatively high degree of accuracy if a consistent outgoing quality level is to be maintained. The blending piles were our solution to this problem.

Jan 1, 1962

By K. E. Stanfield

One of the initial projects under the oil-shale research and development phase of the Synthetic Liquid Fuels Act, Public- Law 290, 78th Congress, approved April 5, 1944, was a survey of oil shales of the United States for the selection of a site for an oil-shale demonstration plant. The oil shales were assayed by the conventional Bureau of Mines retort method proposed by Karrick and described by Guthrie in a more recent publication. From previous experience and that had in making these assays, it became evident that the assay method should be modified or replaced by a more satisfactory one. There are several outstanding objections to the Bureau of Mines oil-shale assay method: (1) the oil yields are frequently smaller than those obtained by other types of assay equipment and by commercial retorts; (2) the assayed oil yield represents only a portion of the organic matter in the shale, which under more favorable conditions, may, Jae converted, more completely into oil; (3) the retorting procedure is controlled mainly by trial-and-error methods; and (4) the assay requires approximately 6 hours for completion.

Jan 1, 1949

By B Murphy, N Strong, J Albrecht

Rio Tinto’s Argyle Diamond Mine has a history of underperformance with delivery of ore from the underground operation to the surface for processing with no real clarity in sources of loss and value. In order to increase underground production performance, the basic concepts of the Theory of Constraints model were applied to the Argyle underground production system. This prompted a revised view on bottlenecks and contributors to value loss and ultimately leading to record breaking mine performance. System loss reporting to demonstrate the best opportunity to drive value, departmental detail to develop tools to identify improvement opportunities and clarity across the team to ensure alignment and clear lines of communication were critical to the project success.

Mar 15, 2021

By E. Tarshizi

Research was conducted to develop a simulation and animation model for an aggregate (sand and gravel) mine operation. This model can assist the mine engineers to investigate and consider the various options of haulage systems which are critical for the mine operation productivity. Discrete-event system simulation studies can be used for the typical haulage issues that mining engineers are often faced with: using truck fleet haulage, conveyor belts, or a combination of both. The simulation has identified some strengths and weaknesses in the current loading and hauling fleet of the mine, and has resulted in some suggestions for improving the system. The simulation includes animation of the operation. Animation is needed to enhance the benefit of any mine simulation model. By combining the visual power of animation with a mine simulation, a complete picture of the mine system is obtained and displayed. The mine is modeled and animated using GPSS/H® and PROOF Professional®, both of which have shown great applicability in discrete mining simulation projects.

Feb 23, 2014

By Ayman Tawadrous, Hendrik Botha, Simon St J Tose

The early miners and their mules always had the challenge of transporting unstable dynamite underground. The modern pumpable explosives, whilst far safer, still present a major logistics challenge for the mobile charging units (MCU). The challenge today is the efficient explosive delivery into declines, ramps, and vertical shafts, often requiring the MCUs to travel excess distances up and down to surface to re-load. Alternatively, the management of cassettes or ISO containers is utilized to deliver the pumpable base emulsion to the MCUs at the working face. Additionally, local laws and regulations regarding shaft clearance further compound the task and result in pausing other operations in the shaft or decline or ramp until the completion of the explosive transport. This paper examines the research & development challenges of dropping base emulsion down a vertical pipe to depths in excess of 1000 m (3280 ft.), either to an underground storage or directly into the MCU, depending on the depth. The boreholes (with pipes) are drilled in close proximity to the underground work areas. The paper also discusses the rheology of the emulsion within these vertical pipes as well as the economic benefits of such an innovative system. The learnings gained from this work, along with examples demonstrating the significant reduction in MCU travel and the safety benefits, are presented for the industry to consider moving forward.

Jan 21, 2025

By J. C. Swartz

New measurements of graphite and cementite solubilities in ferrite have been obtained to resolve disagreements among previous data. To measure graphite solubility, specimens of iron were equilibrated with rarious carburizing atmospheres at temperatures be-twee~z 480" and 1435°C. The carbon activity of each atmosphere relative to graphite was taken from published data. After quenching from each equilibration treatment the concentration of carbon (typically 10 pprn by wt) was determined from the height of the Snoek peak in the internal friction spectrum. A few inclividual analyses by combustion support the reszdts of Smith on the solubility of graphite near the eutectoid temperature. Combination of these combustion and internal friction analyses determines In a, (at 0.01 wt pct) = 24,000/RT - 12.72, where a, is the activtity relative to graphite in ferrite at fixed cornposition. The same specimens were used to determine the solubility of self-stressed cementite precipitates. The results indicate solubilities of 6.3, 23.2, and 68 pprn carbon by wt at respectively 400°, 500". and 600°C. The once large discrepancy between the cementite solubility determined by internal frictiori and that calculated from flee energy data has been almost completely resolved. A recent study1 (hereafter designated I) on the solubility of cementite in a iron did not fully resolve the disagreement among previous data. The remaining disagreement is illustrated by the phase diagram in Fig. L The data of I are represented by the line labeled "stress-free" cementite. They determine a heat of solution of cementite of (14.8 * 0.2) kcal per mole which contrasts with the (20 * 1) kcal per mole derived from Smith's graphite solubility2 and the formation energy of cementite.3 Toward resolving this disagreement we have obtained new data on the solubilities of graphite and cementite. METHODS As in I the Snoek peak in the internal friction spectrum was used to measure the concentration of carbon dissolved in ferrite. This method relies on the relation C=kQ-1 [1] in which C is the concentration of dissolved carbon, Q-I is the Snoek peak height, and k is a proportionality factor which is a function of the peak temperature, polycrystalline texture, and other parameters characteristic of the ferrite lattice. To determine true heats of solution via Eq. [1], it is necessary to establish that k is independent of the temperature from which the specimen is quenched. Some evidence on this point is contained in a separate report.* Additional evidence is shown by the data points in Fig. 1. These represent the Snoek peaks of two specimens carburized to about 10 ppm C, copper plated, and quenched first from 888º then from 588°C. The copper plate was removed before each Snoek peak measurement. These data show that there is no detectable dependence of k on quenching temperature. The solubility of graphite was determined by repeatedly carburizing various specimens of iron wire with gas mixtures of known carbon activity relative to graphite. To cover a wide temperature range within the a phase boundaries it is desirable to use as low a carbon concentration as is compatible with reasonable precision. With the present internal friction apparatus the best compromise of these desires is a concentration near 10 wt ppm. The dashed line in Fig. 1 was used to approximate the activity of carbon* for

Jan 1, 1970

By Patrik Yrjas, Daniel Lindberg, Emil Vainio

Recovery of trace elements from different industrial waste streams is important in realizing the goals of the circular economy. Ash streams from waste combustion can contain high levels of both toxic and valuable trace elements. These elements can be separated during the combustion process based on volatilization and condensation, as well as being separated in post-combustion processes, through thermal or leaching treatment. In this study, an overview is given of the thermal methods for recovery of valuable elements from ash fractions derived from waste incineration. In addition, a case study is presented of the behaviour of ash-forming elements in combustion of MSW and demolition wood, with special focus on the elements Co, Cu, and Sb. In conclusion, it is shown that thermodynamic modeling of high temperature processes can be a useful tool to predict ash behavior both during combustion and in the post combustion treatment of the ash.

Mar 1, 2018

By Alberto Tremea

The eddy current system is universally recognized as a most suitable method to point out discontinuities or modifications on the roll surface. The automation of the controls through the implementation of sophisticated equipments on the grinding machine has favoured its employment in the roll shop. A big effort is still going on to clarify the best way to promptly identify situations that could be really unsafe for the roll life. The results presented in this paper have been obtained through an intensive activity conducted in field by Innse Cilindri on work rolls of finishing stands of hot strip mills. The correct interpretation of the eddy current signals and a good calibration of the automatic system have allowed, in many cases, a substantial optimisation of regrinding practices.

Aug 16, 2017

By D. E. Wolfson

This report presents 900° C BM-AGA carbonization and related data for coals from the principal beds of Nicholas, Randolph, and Webster Counties, W. Va. Thirty-three samples from nine coal beds in three counties were car-bonized at 900° C in the l8-inch-diameter BM-AGA retort, data from which have been correlated with industrial production. Host of the samples were chemically suitable for metallurgical use, and their coking properties were satisfactory. Except for four of the Lower Kit-tanning samples, the ranges of constituents in the coal seams were 1.8 to 9.0 percent ash and 0.4 to 1.1 percent sulfur, values within the range of accept-ability for metallurgical coals. Coke strength indexes were normal for Appalachian coals of similar rank, and the tumbler stability indexes of the coke ranged from 35 to 57.

Jan 1, 1969

By H. G. Linge

Pyrrhotite (FeS1+x ,0<x<0.15) is an iron sulfide which is considered to be a pest in carbon-in-pulp/ leach (CIP/L) gold processing [l].The perceived influence of pyrrhotite on gold processing by CIP/L is a competing consumption of 02 and CN­as the pyrrhotite dissolves by oxidation [1,2]. The few studies of the oxidation chemistry, kinetics and mechanism of the oxidation ofpyrrhotite are reviewed in detail elsewhere [3].There is broad agreement that the surface of pyrrhotite is very rapidly oxidized to form a thin (e.g. 10 nm) ferric hydroxy-oxide layer which overlays an iron-deficient sulfide lattice covering the original pyrrhotite. The reaction can be summarized thus:

Jan 1, 1995

By R. Hogg

Sintering is a process in which the pore structure of an agglomerated powder is modified. For many applications, it is desirable to be able to control the pore structure in order to optimize such properties as mechanical strength and reactivity (availability and accessibility of solid surfaces to reactant gases, for example). In general, these properties will be determined by the total porosity and the pore size distribution of the agglomerate. In the work described in this paper, a physically realistic mathematical model for the sintering process has been developed. The model is based on the usual assumption that the pore system in an agglomerate can be treated as a network of interconnecting, cylindrical pores of continuously varying size. It is further assumed that the total pore length is conserved during the course of the sintering process. Using standard expressions for the rate of shrinkage of an individual pore, the model can be used to predict the changes in total porosity and pore size distribution as sintering proceeds. Experimental pore size distributions, obtained by mercury intrusion porosimetry, for the sintering of oxides appear to be in general agreement with the predictions of the model.

Jan 1, 1977

By G. W. Neumann, J. R. Schnarr

The lead-zinc-copper-silver ores mined by Brunswick Mining and Smelting Corporation Limited at their No. 12 underground mine and No. 6 open-pit operation, and treated by distinct concentration processes in separate plants, present difficult metallurgical problems because of the extremely fine dissemination of the valuable minerals with pyrite and pyrrhotite. The problem of concentration is further complicated, in the No. 12 ore, by the presence of a varying content of graphitic carbon. This paper describes the milling of No. 12 ore and the production of copper, lead and zinc concentrates by differential flotation.

Jan 1, 1971

By B. Hart, D. J. Miller, J. T. Francis, M. C. Biesinger, Smart. R. St. C.

Diagnosis of the surface chemical factors playing a part in flotation separation of a valuable sulfide phase requires measurement of the hydrophobic and hydrophilic species that are statistically different between the concentrate and tail streams. Time of flight secondary ion mass spectrometry (ToF-SIMS) can be used to identify sufficient particles of a specific mineral phase for reliable statistics determining a mean value for each species with 95% confidence intervals (1). Using the region of interest (ROI) facility in the Tof-SIMS software, a mass spectrum from each particle, at 1-2 monolayer sensitivity, is recorded and stored. This analysis is reported for a chalcopyrite / pyrite / sphalerite mineral mixture conditioned at pH 9 for 20 minutes in order to study transfer of copper from chalcopyrite via solution to the other two mineral surfaces since this mechanism can be responsible for their inadvertent flotation in copper recovery. Analysis from mineral selection based on specific ToF-SIMS signals (eg. Pb, Zn, Cu, Fe, Fe/Cu) indicated no statistical difference in the copper intensities on pyrite and sphalerite after this conditioning. Principal component analysis (PCA) of the ToF-SIMS imaging data identifies combinations of factors strongly correlated (positively or negatively) in images or spectra from mass spectra recorded at each of 256x256 pixels in a selected area of particles. PCA is a better method of selecting minerals due to multi-variable recognition. It has clearly separated a statistical difference in copper intensities between the sphalerite and pyrite phases. The method has been extended to samples from an operating plant again with excellent phase recognition and diagnostic surface chemistry.

Jan 1, 2004

By M Erskine, R Mills

This paper approaches tailings dam risk management from the perspective of how other high hazard industries approach the management of their catastrophic event risks, with the aim to provide recommendations from these learnings for the industry to adopt.

Jul 1, 2021

By James L. Hendrix

This paper is intended to give the reader an update on the work being done at the Mackay School of Mines about the fate of cyanide on precious metals mill tailings waste. During the last two years several tailings impoundments have been sampled and analyzed for total and free cyanides. From our sampling program we are beginning to learn valuable information concerning the fate of cyanides in precious metals mill wastes. Included in this paper is a detailed description of our sampling and analytical techniques. Also, some of the data obtained from five sites are given.

Jan 1, 1986

By Sam H. Patterson

Fuller&apos;s earth and bentonite are two clay commodities that are interrelated either by mineral composition or use. Because of this interrelation and the sale of both for many different uses, some ambiguity in their classification has resulted. The term "fuller&apos;s earth" has no compositional or mineralogical meaning, and it is used more or less as a catchall for any clay or earthy material suitable for certain uses. Most, but not all, of these uses require absorbent properties. Bentonite by geologic definition must have formed from volcanic ash or tuff or the glassy material in volcanic rock; most bentonites consist chiefly of montmorillonite but other clay minerals may be present. In industrial usage the term "bentonite" is applied to any clay consisting chiefly of montmorillonite, irrespective of origin. Georgia and Florida have historically been the leading States in the production of fuller&apos;s earth; bentonite has been produced in Alabama on a small scale. The first major use of fuller&apos;s earth was in refining of oils. Other materials have replaced fuller&apos;s earth for this purpose to a major extent, but many new uses for fuller&apos;s earth have been found, and production has increased in recent years. The new uses include absorbent products, insecticide and pesticide carriers, drilling mud, and many others. The bentonite now produced in Alabama is of the "southern," "low selling," or "calcium" type and is used mainly as foundry-sand bond. Most of the fuller&apos;s earth mined now is in the Hawthorn Formation of Miocene age; a lesser amount is produced from the Twiggs Clay Member and other beds in the Barnwell Formation of Eocene age. Inactive pits from which fuller&apos;s-earth was produced from other formations occur at several localities. The bentonite now mined in Alabama is in beds of Cretaceous age; several years ago bentonite was produced from Eocene beds in this State.

Jan 1, 1972

By B. R. Richards, B. G. W. Robinson

"This paper shows how metal values can be profitably won from a comparatively small and remotely located but high-grade orebody. To do so is not uractical for a large mining company, with its necessarily high overhead of services and organization essential to a large producer.To evaluate, develop and profitably exploit a limited but defined ore deposit becomes only a problem of determining the dollars required to win the dollars available. This paper will record how this was carried out during 1965 and at the same time describe the history, development and production plant of this property."

Jan 1, 1966

After a five year period representing the strongest resource and commodity rally ever experienced, we are now faced with a subdued recovery following the global financial crisis. This renewed economic growth will be steady but eventually attain levels that reignite export demand out of China and other emerging nations, which are now reliant on increasing domestic demand to support their economies. This backdrop of weaker share prices and less available investment capital creates a greater imperative for company management to ensure that its share price is fully valued. The mining geologist plays an important role in achieving this outcome through direct estimation of asset value (resources) but also in strongly communicating the æupsideÆ value opportunity in both mine site and adjacent brownfields exploration and an efficient and technically sound mining operation. The contribution of mining geologists to assist in conducting analyst site visits should not be underestimated, particularly with reduced analyst coverage of the resources sector and some simplification in company analysis through ranking companies on Reserve and Resource positions.

Jan 1, 2009