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By Kenneth Gavin

The accurate prediction of the shaft capacity of drives piles in sand continues to present problems for foundation designers. Research in this field has been carried out for many years and has yielded a wide range of design approaches -some of which have been shown by recent experimental work to be based on questionable assumptions. This Paper reviews some of the current popular design methods for piles in sand in the context of recent information obtained from high quality field tests conducted by institutions such as Imperial College London. A database of driven piles in cohesionless soils has been compiled from well documented (and reliable) case histories that have been reported in the literature. The measured shaft capacities of the piles in this database are compared with predictions made by the various methods and an assessment is made of the predictive performance and reliability of each method

Jan 1, 1996

By The Staff

"IntroductionThis paper lists typical liner performance data for various grinding mills at the Noranda, Waite-Amulet, Pamour, and Hallnor mines, and concludes with a comparison of these data, based on wear per square foot of lined mill shell area. Flow-sheets for each of these plants will be found in the reference cited.General InformationTwenty-eight ball-mills and one rod-mill are used by the Noranda organization for grinding ore. These mills, which are shown in general outline in Plate IV, are all of the overflow type and have a cylindrical shell attached to dished heads.Most of them are serviced by hand-operated cranes and none by power cranes. During re-lining, portable tugger hoists are employed to lift the liners and, frequently, to install them in place.The mills vary in length and diameter and the ratio of end liner area to breast liner -area consequently ranges from 1. 6.75 in a 5 ft. by 14 ft. mill, to 1:2.28 in an 8 ft. by 8 ft. mill."

Jan 1, 1950

By Stephen C. Tadolini

The U.S. Bureau of Mines conducted a laboratory investigation designed to evaluate the stress and deformation characteristics of fully grouted roof bolts subjected to various magnitudes of end loadings. The experiment and subsequent analysis were completed, utilizing axial deformation data obtained -ultrasonically from forty-one 4-ft, grade 40 roof bolts, with a total of 132 measurement locations along the lengths of the bolts. The ultrasonic measurement instrumentation used in this investigation allowed for elongation measurements without requiring extensive bolt modifications. The results indicate that approximately 39 pct o{ the applied end load dissipated within the first 3.4 in of the bolts. However, only 3 pct of the applied load was realized beyond 28 in of the grout column. Data are presented individually for every 6-in increment of bolt length, and analysis was performed using statistical, nonlinear equations developed for 5,000 and 8,000 lb loading conditions.

Jan 1, 1990

By Morgan Schauerte, Laura Raimondi, Mariel Palomeque

Executives in the mining industry are facing dramatically changing market expectations on reporting and transparency regarding the environmental and social impacts of projects, supply chains and products. Companies increasingly need to disclose the governance procedures they have in place to ensure communities, investors, employees, and Indigenous partners are effectively managing social and environmental risks. These disclosure requirements begin during exploration and carry through to all stages along the project life cycle. This type of environmental, social and governance (ESG) disclosure is referred to as ESG performance by the investment community. ESG is not a new concept, and it builds on and is intertwined with many concepts such as corporate sustainability, corporate social responsibility, eco-efficiency, triple bottom line thinking, life cycle management and many others. This paper will explore how mining companies can develop a credible ESG governance approach and strategy that will reduce risk, open opportunities, and create value. This paper will summarise ESG trends and drivers, discuss the economics and investors’ perspective towards ESG, and outline leading ESG standards and guidelines of interest to investors, regulators, communities and other stakeholders. Linkage of ESG to global sustainability efforts such the United Nations Sustainable Development Goals and Global Compact will also be addressed.

Jan 1, 2023

THE Yallourn chimney has aroused interest, as it is, for the time being, the tallest structural erection in Australia. Its height was not decided on, however, with the object of breaking records, but is purely incidental to the purpose which it serves. Theboiler plant at the briquetting works (first instalment) consists of five Babcock and Wilcox land-type water-tube boilers, each of 4510 sq ft. heating su:r£ace and 225 sq. ft. grate area in the form of step grates. Four boilers will normally produce 73,000 lb. of steam per hour at a gauge pressure of 265 lb. and a temperature of 6500 F., the fifth boiler being a reserve. Each boiler will consume about 100 tons of Yallourn coal per 24 hours. Provision is made for future installation of economizers, should it be found desirable. Designing for this condition, and allowing for a waste gas temperature of 3500 F. and an air temperature exceeding 1000 it was found necessary to have a draft of about 1.3 in. (water gauge) at the base of the chimney, and to deal with about 2000 cub. ft. of gases per second. Estimates were made of the cost of providing the necessary draught by means of fans and by means of a tall chill).ney. The annual charges of the two methods differed only slightly, and the tall chimney wasselected as being the more general practice in briquetting factories.Estimates were prepared for brick and concrete chiIlllleys. Yallourn bricks at that time were hand-made, and, while very suitable for domestic work, were not capable of withstanding high compressive stresses. The chimney design to suit these bricks thus required to be on very ample lines, resulting in high cost. Machine-made bricks from Melbourne would cost about £5 10s. per thousand on the site, with extra for radials, so that high cost again resulted. On the score...

Jan 1, 1924

By J. H. Zietsman

It has previously been observed that industrial high-titania slags display a compositional invariance, remaining close to stoichio-metric M3O5. The present study focuses on this invariance and the phenomena which may cause it. The invariance was studied using thermochemical calculations and a mechanism is proposed for the observed behaviour. The mechanism suggests that a combination of thermochemical equilibrium and transient slag solidification and melting results in the observed compositional invariance. The proposed mechanism provides new insights and prompts questions about other mechanisms in the smelting process.

Jan 1, 2004

By Jean Cayouette, Paul Blatter, Paul Cousin

"The Laronde mill was commissioned in 1988 and has been treating the Laronde Penna ore since 2000. The Laronde plant, situated in the Abitibi region of Quebec, has experienced mill expansions to accommodate 7500 mtpd and to recover gold and silver as well as important amounts of base metals (Cu, Zn, Pb). Ten sequential metallurgical and environmental processes are responsible for metals recovery and process viability. Over 200,000 ounces of gold, 4,5 million ounces of silver, 7000 tonnes of copper, and 78,000 tonnes of zinc are produced annually.In 2008, the Goldex plant began trucking high grade (35-45 g/t Au) pyrite sulphide concentrate (TCGO) for gold extraction at a newly constructed treatment plant, increasing gold output at Laronde by 40,000 ounces. In 2009, the high gold grade Lapa ore processing facilities were annexed to the Laronde plant increasing output by 120,000 ounces of gold. TCGO and Lapa productions are forecasted until 2018 and 2015 respectively, with known reserves of each mine.Today, up to 140 permanent employees run and optimise the Laronde plant operation. As a result, Laronde has intricacies intrinsic to a large and varied operation. The paper will outline the metallurgical highlights, challenges, and future outlook related to the treatment of each ore type (Laronde, TCGO, and Lapa).INTRODUCTIONFollowing the 2000 to 2003 expansions, the Laronde plant evolved into a mature milling complex with developed processing, man power, and water treatment capabilities able to accommodate the complex Laronde ore. The ore requires a series of grinding, copper/lead flotation and separation, zinc flotation, zinc tails precious metals leaching, followed by a counter-current decantation circuit and Merrill Crowe precipitation. A paste backfill and SO2-air cyanide destruction operate intermittently. The tailings area has a dedicated cyanide destruction and metals precipitation plant prior to water recycling to the mill. A biological water treatment plant was put into service in 2004 to address the build-up of thiocyanate in the tailings ponds at Laronde. This was the result of the high sulphide content of the Laronde ore and 90% recirculation of the process water. The plant uses bacteria to oxidize and destroy thiocyanate, and removes phosphate from the water before it is released to the environment."

Jan 1, 2011

By S Hapugoda, J R. Manuel, M J. Peterson

Microindentation testing using the square–pyramid–shaped Vickers indenter is a well-established technique to determine the microhardness of minerals and materials. However there is a paucity of published microhardness data from Fe ore samples. It is acknowledged that an iron ore’s particle mineralogy and texture is critical to its processing properties, and it is therefore considered that the microhardness of different mineralogical/textural types may also relate to these properties. Mineral microhardness potentially provides inputs to the modelling of breakage characteristics during comminution, as well as the relationship between mineral chemistry and microhardness, and mineral microporosity and microhardness. Microhardness can be determined as single crystal microhardness, for more coarsely microcrystalline samples, or as ‘aggregate microhardness’ for cryptocrystalline or finely microcrystalline samples.Variations in the texture and mineral chemistry of common Fe ore minerals (eg martite and microplaty hematite, ochreous and vitreous goethite etc) are well established and this study provides microhardness data on different textural forms of Fe (oxyhydr)oxides from a variety of different Fe ore deposits. The data indicated that in general, the mineral grain size, microporosity and texture were the main influences on Fe (oxyhydr)oxide microhardness. There were no apparent systematic variations between microhardness and minor element mineral chemistry, with the possible exception of Al content in goethite (for goethites with Al content >0.5 wt per cent), and for goethite total element contents >90 wt per cent (determined by electron probe microanalysis, EPMA). Higher Al concentrations and lower total element concentrations in goethite EPMA analyses correlated with lower goethite microhardness. Microporosity and grain size were more important than texture to hematite microhardness. Different textural forms of dense hematite (eg martite, recrystallised interlocking hematite and specular hematite) with similar grain size exhibited comparable microhardness. Microhardness values for hematite and hydrohematite with little or no evident microporosity were also similar, whereas more porous forms of martite, microplaty hematite or hydrohematite exhibited lower microhardness.CITATION:Peterson, M J, Manuel, J R and Hapugoda, S, 2017. Microhardness testing of hematite-goethite Fe ores – implications for their textural characterisation and geometallurgy, in Proceedings Iron Ore 2017, pp 319–330 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By W. R. McDonald

Part of the U.S. Bureau of Mines mission is to supply the U.S. mineral industries with information that is useful in planning to meet the Nation's critical and strategic mineral needs if a national emergency occurs. The Bureau conducted laboratory research including operating a nominal 100 lblh pilot plant to demonstrate the recovery and concentration of chromite by gravity and flotation operations from three northern California mineral deposits. Gravity beneficiation test results show that concentrates contained as much as 52 pet chromic oxide (CrZ03) with recoveries of about 80 pet. Results from the bench-scale unit operations of mineral liberation, tabling, vanning, spiraling, pinch sluice, work index, and thickener area determination tests are presented in this report.

Jan 1, 1990

By S Taylor, B Lumsden, G Long

Statistical metallurgical plant trials are becoming more widespread, as a valuable tool for increasing plant profitability. Generally, a single parameter like metal recovery varies under the trial condition while all other variables such as average metal feed grade or average metal concentrate grade are equal for the two test conditions during the period of the test. Metal recovery is usually the measured variable because concentrate grade is fixed by smelter terms, and plants operate to maximise recovery at the required concentrate grade. However, in all flotation plants there is a relationship between concentrate grade and metal recovery, and under the same conditions increasing one results in a decrease in the other. At MMGÆs Rosebery Mine the zinc concentrate produced is generally above smelter specifications, so zinc concentrate grade can vary during a test. During trialling of magnetic conditioning in the Rosebery zinc circuit, the difference in both zinc recovery and zinc concentrate grade were analysed. The analysis of changes in zinc grade and recovery during the trial raised some interesting questions about the relationship between concentrate grade and recovery. A paired statistical method was developed and tested to combine in each pair the change in concentrate grade and recovery in a single result that could be analysed by a paired t test. This method was found to be very sensitive to combined, varying changes in concentrate grade and/or metal recovery. It was also evaluated on plant test results from another flotation plant to verify its applicability in other plants. CITATION:Long, G, Taylor, S and Lumsden, B, 2012. Statistical plant trials - Efficiently combining concentrate grade and metal recovery results, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 355-362 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By R. M. Goktan

Rock brittleness plays an important role in the cutting action of picks on rock surfaces. It controls the ease with which cracks can propagate through the rocks. Although rock brittleness is known as a property that contributes to the cuttability of rocks, despite considerable research effort, there is still much uncertainty about the relation between rock brittleness and rock cutting efficiency. This fact can be attributed to the lack of a universally accepted brittleness concept and a brittleness measurement method. The existing publications of some researchers have, in a way, tended to confuse the understanding of brittleness in the general field of rock excavation where it is expected that the energy consumption of cutting should decrease with increasing brittleness of rock, other conditions being equal. However, this sometimes conflicts with the brittleness concept commonly used in rock mechanics, where the more brittle the rock the higher its mechanical strength. The ratio of rock compressive strength to tensile strength is considered by many authors to give a valuable brittleness index for drag pick operations. Hence, in this contribution the ratio of uniaxial compressive strength to tensile strength BI is considered as an index of rock brittleness, and a new methodology is proposed for its use in rock cutting efficiency analyses of drag tool operations. Validation of the suggested approach is supported by available experimental data in the literature. Contrary to the conclusions reached previously by other authors, it is shown that an increase in rock brittleness is accompanied by an increase in the cutting efficiency, other conditions being equal. Keywords: brittleness index, rock brittleness, cutting efficiency, specific energy, rock excavation.

Jan 1, 2005

By J. P. Morris

"INTRODUCTION In the investigation being conducted by the Bureau of Mines concerning the production and utilization of sponge iron, it soon became evident that more information was needed regarding methods for determining the degree of reduction attained in the manufacturing process. Sponge irons made by different processes vary in physical characteristics and chemical composition, and a method of analysis that is suitable for one type is not necessarily applicable to all others. For example, the hydrogen-evolution method, which measures the volume of hydrogen evolved upon treating the sample with acid, accurately determines the oxygen content of some types of sponge iron. However, when the sponge iron contains combined carbon, hydrocarbon gases are also-evolved and large errors may result. Probably no single method will give accurate results in all instances, and for this reason it is desirable to have several reliable procedures available and to know the limitations of each.For measuring the degree of reduction, determination of either metallic iron or oxygen should suffice, although for practical application of sponge iron to the production of steel the oxygen content is more significant. After consideration of proposed methods of analysis in regard to their suitability for routine use and the probable influence of other substances, four procedures were chosen for investigation:(1) Mercuric chloride method.(2) Copper sulfate method.(3) Hydrogen-reduction method.(4) Hydrogen-evolution methods."

Sep 1, 1945

Recent data contributions to New Zealand Mesozoic terrane geology confirm the consensus interpretation thatNew Zealand grew by the progressive addition of material by plutonic and accretionary processes along the Gondwana margin. The data also: 1. emphasise the discontinuous but inter-related nature of these processes of continental growth, 2. better establish a direct Gondwana correlation of the Western Province and probable Gondwana provenance of at least some of the Eastern Province, 3. suggest specific times and places when passive or strike-slip rather than subduction regimes are recorded along the south Gondwana margin, and 4. potentially lead to interpretations emphasising parautochthonous rather than far travelled relationships between many New Zealand terranes.  

Jan 1, 1995

Minerals processing needs a step change in energy efficiency. While the search for new technology breakthroughs is important, huge gains are still available by better using existing research outcomes. This potential remains untapped due to a combination of organisational 'silos', inappropriate performance measurement, and poor science in some areas. It is time to see the elephant in the mill.

Sep 13, 2010

By A. R. Chambers

Malagash received its name from the Indians many years ago on acco.unt of its turbid (milky) waters, although,' the red men did not appreciate the significance of this turbidity, and were, of course, entirely ignorant of the crystal beds of pure salt that lay beneath their feet. The salt lake of the Mississippian, or Lower Carboniferous period, in which these beds occur, was apparently a large one, for there is evidence of its existence at intervals all the way from Sydney, Cape Breton, to St. John, New Brunswick, 300 miles as the crow flies, and there is no knowing what its other dimensions may have been, as much of this horizon is now buried on the one side beneath the waters of the Gulf of St. Lawrence, and on the other underneath the Atlantic ocean. About midway of the area and underlying the counties of Colchester and Cumberland, there occurs a synclinal basin of which the Malagash salt outcrop forms only a small portion of its northern limit. This basin has been described very fully by A. C. Hayes. (1) The operations carried on at Malagash since Hayes wrote his report have brought to light very little in the way of new geological data, except to confirm his pre-dictions as to the probable faulting of the salt strata, and the effect which these faults would have on mining operations.

Jan 1, 1924

By KENNETH W. GREENAWALT, William Greenawalt

THE patent system, through which an inventor is given exclusive right to his invention for a limited period as a reward for his industry and in reimbursement of his expenditures, originated in England in the famous "Statute of Monopolies," enacted in 1623. The first patent granted in America was to Samuel Winslow, in Massachusetts, in 1641. The basis of the patent system of the United States is a provision in the Constitution giving Congress the power to secure to inventors for a limited time the exclusive use of their discoveries. The first legislative enactment was the law of 1790, which was placed on the statute book after Washington had addressed Congress in its favor. Under this law, the Secretary of State, the Secretary of War, and the Attorney General constituted the board for the examination of patent applications and the granting of patents. The first Secretary of State, Thomas Jefferson, became the first administrator of the patent sys- tem in this country. He personally examined every application filed during his term of office.

Jan 1, 1930

By D. J. Burdon, Anthony Caplan

"(1) The radiological appearances of pneumokoniosis on the Kolar Gold Field is described in detail. The characteristic abnormality is the. presence of a diffuse, fine annular and punctate mottling. (2) The frequency of symptoms could not be determined with any degree of accuracy, but it is believed that symptoms are absent and there is no incapacity until profuse radiological mottling is present, i.e., after long exposure to dust. (3) There is an increased predisposition to tuberculosis, which, if it occurs, affects the prognosismost unfavourably.(4) Pathological examination shows that the radiological mottling is due to the presence inthe lung of numerous small dust-cdll aggregates (up to T5 mm. in dia.) deposited around the smaller bronchioles and blood-vessels.(5) The dust-cell aggregates are relatively acellular but when tuberculosis is superadded thereis an excessive cellular and fibrotic reaction.(6) The difficulties of defining the radiological and pathological appearances of early pneumokoniosisare discussed.(7) The incidence of pneumokoniosis in 7,653 workmen with 5 or more years’ undergroundservice was 43-75%, but it is suggested that in future the incidence will be appreciably lower.(8) The methods of- dust production and the chemistry of mine dust are described. It isshown that the free silica-content of air-borne mine -dust is relatively low.(9) The aetiology'of the pneumokoniotic lesion is discussed."

Jan 1, 1947

By A. B. Parsons

DOWN in Washington an army of individuals constituting the government of a so-called "'democratic" nation is trying to manage the conduct, in its rnultifold phases, of the greatest war in history for the country that is potentially, at least, the strongest in the world and on which, consequently, the major responsibility rests. The enterprise is one of unprecedented magnitude and complexity. That individuals and groups have made and are making serious blunders, both as to the establishment and execution of policy, is to be expected.

Jan 1, 1942

By John Dasher

The analyses reported on in this paper indicate that there are hydrometallurgical routes from sulphide concentrates to copper that are potentially competitive with smelters which are not permitted to emit sulphur oxides. The various hydrometallurgical processes, and their economics, are discussed.

Jan 1, 1973

By Mark R. Pettitt

The results of an extensive research and development program to reduce the noise generated during coal cutting are presented. The characteristics and magnitude of continuous miner coal cutting noise sources are defined. This work consisted of development of a simulated coal ,cam to facilitate above-ground coal cutting tests, noise measurements in a reverberant acoustic chamber during simulated mining operations of a continuous miner (cutting the simulated coal scam), and noise measurements in an underground coal mine during continuous miner operation. In-mine and laboratory test results were in excellent agreement for both A-weighted overall levels as well as A-weighted one-third octave band spectra. Methods to reduce coal cutting noise are presented. These methods take full advantage of the dynamic characteristics of the forces generated during coal cutting. Dynamic cutting force isolation was shown to be a very effective technique. Finally, a continuous miner was equipped with a cutter head that incorporated (among other design factors) cutting force isolation. Successful, lung term, in-mine use of the cutter head demonstrated coal cutting noise at the operator's station of less than 90 dBA and 50% coal, 50% rock cutting of less than 93 dBA.

Jan 1, 1985