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By N Weerasekara, M Powell, P Toor

The effect of liner wear on SAG mill performance has gained much attention in recent years. It is commonly observed that the three key performance criteria of SAG milling; throughput, power and product size all improve as the liner wears.The increase in throughput is generally ascribed to the increase in the grate apertures and the increase in mill volume due to the wear of these components. Whilst the decrease in product size is attributed to the reduction in lifter height and angle, resulting in more breakage by means of attrition and abrasion.Though it is widely acknowledged that the wearing of liner components such as Lifters, Plates and Grates have a significant impact on mill performance, their individual contribution to changes in mill performance has been unclear, and resultantly lead to questions like; what percentage of the throughput increase can be attributed to the increase in mill volume (plate wear)? and how much can be attributed to the increase in grate aperture (grate wear)?It has been found that through the use of grinding surveys, analysis of production data and JKSimMet it was possible to separate the effects of changing liner profile, increasing mill diameter and increasing grate aperture on the mill performance allowing for the quantification of each.The outlined methodology allows for both troubleshooting of problem liner components which reduce milling efficiency in their wear life as well as providing a basis for a more quantitative approach to liner design and reline scheduling.CITATION:Toor, P, Powell, M, Hilden, M and Weerasekara, N, 2015. Understanding the effects of liner wear on semi-autogenous grinding mill performance, in Proceedings MetPlant 2015, pp 150–161 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Roy Woodall

Successful mineral exploration is the lifeblood of the mining industry. Contrary to what the environmental lobby would have the world believe, the industry is replacing the metals it is extracting. The reserve base has not changed significantly in 20 years (Fig. 1.) Mineral exploration is a research activity. First there is the idea, the vision or the intuitive thought. The experiments follow. These involve repeated phases of data gathering, data interpretation and concept testing through drilling. For many companies, exploration is the main investment in scientific research. Each mineral exploration experiment may involve years of costly work. Despite the improving tools of science and technology, the investment remains high-risk. Only the promise of high rewards, or desire to survive as a mining company, will stimulate the necessary commitment and level of investment. Confidence that an economic return can be achieved, confidence in the science and technology being applied and confidence in the people involved are the foundations upon which successful mineral exploration is built (Woodall, 1984). The challenges facing the explorationist in the 1990s fall into two categories: - the challenge to make the activity economic; and - the challenge to make the activity socially and, therefore, politically acceptable.

Jan 1, 1992

By R. Farnfield, W. Birch

Arguably, some of the most restrictive statutory blast vibration requirements attached to mineral extraction operations can be found in the United Kingdom. Such limitations are, as a rule for the UK, stipulated together with a required statistical confidence that has to be observed in the blast design process in order to ensure total planning compliance. A key element in this procedure is the effect imparted by vibration data scatter from previous blasts as this becomes reflected in the site’s operational standard error statistic and in turn directly influences the maximum instantaneous charge weights that can be justifiably employed. The greater the scatter, the lower the compliant charge weights become.

Jan 1, 2006

The mineralisation consists principally of layered pyrite, phalerite and galena, situated conformably within a sequence of tuffaceous, bituminous shales and dolomitic sediments that include slump breccias. The sediments show little evidence of post sedimentary reconstitution. A volcanic-exhalative-sedimentary origin is postulated for the mineralisation. Attention is drawn to the similarity between the McArthur deposit and the lead-zinc-silver orebodies at Mount Isa. The primitive nature of the sulphides is reflected by their adverse metallurgical behaviour, and it seems that the best prospect for milling and flotation benefication may lie in the production of separate zinc and bulk concentrates

Jan 1, 1968

By Aminul Islam, Vinay M. Kumar

"About 100 Hectares of land reclamation over the very soft to soft marine clay at Uran Creek in Maharashtra is planned. The depth of marine clay varies from 10m to 24m as observed from the geotechnical investigation. The marine clay was treated with Pre-fabricated Vertical Drains (PVD’s) installed from the elevation of +5.5mCD (chart Datum) and preload/placement of surcharge. A Settlement of soft soil mud under the reclamation was monitored using magnetic extensometer (M) and ground settlement maker (S2). These instruments are installed after constructing working platform at around +5.5m CD. Based on the field instrumentation data, the consolidation parameters were adjusted to match the theoretical and actual settlement plot. The author called this approach as “Back analysis method”. The objective of this paper is to present a case study of instrumented preloading treatment for a thick marine clay deposit. The degree of consolidation in clay strata was determined from magnetic extensometer and ground settlement marker data. Authors also determined degree of consolidation as Asaoka method, Hyperbolic method and Back analysis method and compared the results.INTRODUCTIONExpansion of Container terminal with port buildings, rail container depot, roads and utility buildings at Jawaharlal Nehru Port Trust (JNPT) is planned over a reclaimed land of 100 hectares. Uran creek predominately consists of the estuarine deposit of very soft to soft marine clay. They are characterized by low shear strength, very low bearing capacity and exhibit large settlement when subjected to loading. The additional load causes the significant magnitude of consolidation settlement over a considerable period of time. Thus for development projects on top of soft soil, the postconstruction settlement would be of primary concern.To accelerate the consolidation pre-fabricated vertical drains (PVD) were used. Pre-loading procedure was adopted to minimize the post construction total and differential settlements. PVD’s were installed at 1.0m and 1.2m c/c triangular pattern. Locally available borrow material is used as a reclamation material. The reclamation material has been placed over the existing sea bed level by land based method/end tipping method and created the working platform. The level of working platform is decided based on the tide data and it has been selected such that work should be affected during highest high water level. The PVD has been installed from the working platform and subsequently all the field instruments have been installed from the same level. Five different types of field instruments are installed to monitor ground improvement works."

Jan 1, 2017

By T. Yalcin

In the Box-Wilson method, the correlation between dependent and independent variables is represented by a polynomial response function, whose constant and coefficients are determined by applying regression analysis to the experimental data collected. The five levels used for each variable consist of a minimum, a maximum and three intermediate values. A study was carried out using Ni-Cu ore from Sudbury, Ontario, in which 15 experiments designed according to the Box-Wilson method were carried out in random order and in duplicate. The two sets of replicate data showed close similarity, with an overall variance of 0.311 for the five parameters studied. The response functions were used to optimise frother dosage, collector concentration and air flow rate and an experiment was then carried out under the optimised conditions; the results agreed closely with those predicted by the response functions

Jun 21, 1905

By Ming Ju Liu

China has been suffering from the most serious coal and gas outburst accidents. The situation has become worse than ever with the mining of deeper coal seams at higher production rates in a more complex underground mining environment, in order to meet the huge national demand for coal-fuelled power plants. In the year 2007 alone, more than 30 outburst accidents occurred in underground coal mines with a death toll of 258, and in the year 2008, as of May 22, nine outbursts have already occurred in Henan, Hubei and Chongqing, killing 68 workers. At the same time, China also experienced new trends of coal and gas outburst accidents since its coal production boom in the year 2001. These trends are of great importance for government agencies, coal mine owners and operators to take initiative and effective measures to prevent and control the occurrence of coal and gas outbursts in China?s widely spread outburst prone mining areas. This paper presents outburst data of China coal mines since 2001 and describes new trends of outburst occurrence in recent years, which include outbursts coupled with shocks or rock bursts of competent roof, outbursts in mines under development, outbursts in new mines and mines that have never suffered outbursts before, outbursts in mines that are believed to be of low gas content as well as outbursts in more long-wall faces. Based on the observation of outburst occurrence in China in the period from 2001 to 2008 as well as mining and geological conditions, detailed analysis of the possible causes that led to those new trends of outburst accidents is conducted. The analysis helps shed light on possible future remedies and the necessary measures to alleviate or eliminate outburst accidents in underground coal mines. Suggestions are put forward on future studies that could be of interest to national and provincial government agencies regarding strategic policies, proper technical management practice, identification of outburst prone coal seams, online monitoring of impending outbursts as well as prevention and control measures.

Jan 1, 2008

By J. Kerr

The first stage of the development of a new modified 201-type low nickel austenitic stainless steel is described in this paper. The alloy is intended for use as a structural alloy, and so requires a yield strength >400MPa as well as acceptable weldability and toughness. The low nickel content will give a lower material cost in comparison to more conventional austenitic grades, and the processing route is required to be similar to that of Type 304 to keep the processing cost low. The base alloy was designed using empirical methods developed for stainless steel, and the properties of the base alloy were verified using a range of small-scale melts. The base alloy had a 0.2% proof strength of ~320-400MPa, and so it is planned to use V additions of ~0.15% to bring about precipitation strengthening in the hot rolled condition, so raising the alloy?s proof strength above the 400MPa minimum.

Jan 1, 2004

By Wallace W. Roepke

The Bureau of Mines conducted a series of experiments using Illinois No. 6 coal to determine the effect of asymmetric wear on airborne respirable dust (ARD), specific energy, cutting force, and normal force. Plumb-bob-type bits--one new bit and four ground with different sized flats--were used. Constant-depth linear cuts at 0.32, 0.64, 1.27, and 2.54-cm cut depths were made. Both cutting force and normal force increased as the flat area increased. Specific energy demonstrated a statistically significant increase with flat area at the 0.32-and 1.27-cm cut depth only. Specific ARD showed a statistically significant decrease with increasing flat area only at the 0.64-cm cut depth. Increasing cut depth increased cutting force but decreased specific energy and specific ARD. Normal force increased with increasing cut depth for the new bit but exhibited a maximum at 0.64 cm for the bits with flats.

Jan 1, 1983

By L. J. Leach

Quench and tempered Cr-Mo plate steel was found not to contain a fully martensitic structure as a result of either slow slack quenching or insufficient hardenability at the cooling rates used. The resulting microstructure contains bainite in combination with martensite. It is necessary to examine the implications of bainite for the toughness of the final product. Loss of toughness arises primarily from the inter-lath carbides that typically form in upper bainite. An investigation into the effect of upper bainite in a martensitic matrix of a steel grade containing 0.17% C, 0.1% Cr, 0.54% Mo, and 20 ppm Bindicated lower toughness than in a fully martensitic structure.

Jan 1, 2013

By Horace C. Porter

Much has been written of the changes undergone by coal in storage and the deterioration of coal through exposure to the weather. In order to obtain definite information for the benefit of the Government departments and of all who store coal in large quantities, a series of tests was begun in the fall of 1909 under the supervision of J. A. Holmes, then chief technologist of the United States Geological Survey, and was continued by the Bureau of Mines after its establishment in 1910. The tests were confined to determinations of the loss in heating value of the coals and did not include a study of other deterioration; for example, in coking quality or the yield of by-products in coking. The Bureau of Yards and Docks of the Navy Department cooperated in tests of New River (W. Va.) coal, a variety largely used by the Navy. A preliminary report presenting a brief account of the early results of these tests has been published by the Bureau of Mines as Technical Paper 16.a The detailed report is presented in this bulletin, which gives a full account of the tests and the analytical data covering a period of five years' storage. Data of somewhat similar experiments for shorter periods with gas coal from the Pittsburgh bed, with Pocahontas coal on the Isthmus of Panama, and with Sheridan, Wyo., subbituminous coal, which is used for railroad and other purposes in the West, are included.

Jan 1, 1917

By D. Z. Mraz, R. S. Jones

Unlike in coal mines where caving methods are used, the subsidence over potash mines in Saskatchewan, Canada, is a function of gradual mining convergence. Because of the presence of high pressure water aquifers over the evaporite salt formations, the mines have to be designed as regionally stable and no caving is allowed. The extracted area converges gradually and the convergence is mainly a function of the extraction and the mining method employed. Consequently, the subsidence rate is very slow and the bridging of the over-lying strata is a considerably more important phenomenon than elsewhere. The paper evaluates a case history of convergence and subsidence in a deep potash mine in Saskatchewan.

Jan 1, 1986

The Mining Foundation of the Southwest (MFSW)promotes public understanding and education related to the mining industry. Towards this goal, the Foundation has funded several projects from donations and fundraising activities. The MFSW was incorporated in 1993 by combining the Mining Club of the Southwest and the Mining Club of the Southwest Foundation. The Mining Club began in 1971 as a social organization. It provided members of the mining community an opportunity to meet. The club also provided a means for public education about mining. In the early 1990s, the club’s efforts were directed mainly toward educational activities. And in 1992, discussions began concerning incorporation into a non-profit foundation to further the public understanding of mining. In 1983, the American Mining Hall of Fame was inaugurated to honor significant contributors to the industry and profession. The Hall of Fame serves to educate people about prominent persons associated with the mining industry, present and past. The honorees number 75. Plaques commemorate their induction and are on display at the Arizona Historical Society’s Museum in Tucson, AZ. The combined honors ceremony and banquet have remained one of the fund raising activities.

Jan 1, 1999

By G. M. Steed, A. O. Oyinloye

The deposit lies in amphibolite-facies biotite granite-gneisses of Proterozoic age, 4 km east of a major crustal break known as the Ifewara-Zungeru fault. Gold mineralisation is contained in a zone of quartz-carbonate (mainly calcite) veins and hydrothermally altered gneisses with associated small-scale intrusions along a steeply dipping second-order fault zone that roughly parallels the main fault. Gold is present mainly at grain boundaries between quartz and carbonate as discrete particles up to 100 micrometres in size, in general association with sparse, scattered pyrite, pyrrhotite and some base metal sulphides. Adjacent to the gold-bearing zone the granite-gneisses have been hydrothermally altered with minor volume increase, most notable enrichment being in K2O, S, Pb and Cu (and Au). High concentrations of Th, Y, Ce and Zr in the granite-gneisses imply derivation from S-type granites. It is likely that their high heat production capacity maintained the high temperatures needed to transport gold in the hydrothermal systems. It is most probable that the mineralisation dates from the Pan-African orogeny (650-450 Ma)

Apr 1, 1996

By R. J. MacLeod

"INTRODUCTIONThe removal of water or liquid from slurries and solutions is a procedure generally present in many process industries. This has prompted the development of many mechanical and thermal devices with which, I have no doubt you are al1 familiar.In the mining industry, beneficiation of ores necessitates ' the removal of water or other 1iquid from the concentrate material. The most common method of accomplishing this is by means of thickeners, vacuum filters and rotary dryers, generally all three and in that order;The use of spray drying techniques to obtain the same end has many advantages and these will be outlined here.THE PRINCIPLE OF SPRAY DRYINGA Spray Dryer consists of a cyclone shaped chamber where hot air and atomized concentrate are introduced in the upper section. (Sec figure No. 1). Efficient mixing of these two streams produce dry concentrate and moist spent air, both of which are removed from the base of the chamber.Thermal dewatering involves the product ion of heat and spray drying has no special requirements in this area. Generally a direct fired air heater is used and the products of combustion whether they stem from the use of gas, oil or coal fuel go into the spray dryer along with quench or dilution air which is used to reduce the combustion gases to the desired temperature. This generally lies in the range of 1,000 to 1,600° F. In spite of these relatively high inlet temperatures, the spray drying process eliminates the need for refractory lining or indeed any special heat resistant metals except on the air inlet ducting. Waste heat may also be used even if a significant amount of contamination is present."

Jan 1, 1972

By Edwin M. Thomasson

HELIUM SHIPMENTS in 1964 exceeded the volume shipped during the previous year for the 15th successive time. Shipments from Bureau of Mines helium plants were 667.4 million cubic feet,2 about 6 percent more than in 1963. Production at Bureau of Mines plants totaled 784.5 million cubic feet. An additional 3,193.1 million cubic feet, which was produced by private companies participating in the helium conservation program, was purchased by the Bureau and stored underground for future use. The Bureau of Mines continued to sell helium at $35 a thousand cubic feet, the price established in 1961. Substantial railway freight rate reductions for tank car shipments of helium went into effect during the year, resulting in a lower delivered price for helium. As the Nation moved ahead in the space age, it became increasingly apparent that helium would continue to play an essential role in research, in technology, in defense, and in industry.

Jan 1, 1965

By J. Cooperman

THE INVESTIGATION was carried out in three stages, depending on the objectives of the work and the kind of equipment used. The first stage involved testing of 11 representative Alabama coals, the source of which is given in table 1. The objective was to find whether these coals could be gasified raw by the Lurgi method, and the equipment used was a 4-inch batch generator (to be described later). This generator proved too small and difficult to control to provide adequate amounts of products under continuous operating conditions for testing. For the second stage, a 6-inch batch generator was used, which was provided with facilities for superheating the steam-oxygen mixture and for synthesizing additional methane from the residual carbon monoxide and hydrogen in the primary Lurgi gas. Selected Alabama coals, Pittsburgh-bed coal from West Virginia, "Disco," and anthracite were used. For the third stage of the work, a continuous generator of 1 square foot grate area, following closely the design of the industrial generators operated in Germany, was provided. This generator was designed by 0. Hubmann, engineer for the Lurgi company, and was expected to give results closely simulating industrial-scale apparatus. The purpose of this equipment was to test prepared materials shown to operate smoothly in the 6-inch generator under conditions approximating as nearly as possible those prevailing in industrial practice. Work of the first stage showed that Alabama coals could not be used in the Lurgi process without first destroying the coking power.

Jan 1, 1951

By D. F. Strong, P. P. O'Neill

"The Isle aux Morts Prospect is the first polymetallic, sulphide mineralization reported from the Port aux Basques Complex of southwest Newfoundland. Zn-Pb-Cu-Ba-Ag mineralization hosted by quartz-muscovite semipelite, occurs at the contact between a quartz of eldspathic unit and pelitic unit with intercalated amphibolite are minerals comprise sphalerite-galenachalcopyrite, in order of decreasing abundance. The principal gangue minerals are quartz, muscovite, feldspar and barite. Three morphologic types of mineralization are present: massive with more than 50% sulphide, flanked on one or both sides by disseminated and/or banded types. The massive type of mineralization exhibits a :durchbewegung"" fabric of rounded silicate fragments in a sulphide matrix, characteristic of intensely deformed and metamorphosed sulphide bodies. Sulphide minerals have been mobilized and recrystallized and share the same metamorphic and deformational history as the host rocks. Quartz muscovite schist which hosts disseminated mineralization, displays a K2O enrichment and Na2O depletion, that is typical of alteration associated with sulphide bodies in volcano sedimentary sequences. Isotopic ratios of sulphur are comparable to those of volcanogenic massive sulphide deposits.Despite penetrative deformation and metamorphic recrystallization, features of the local geology and the mineralization suggest that the Isle aux Morts Prospect is volcanogenic in origin. IntroductionFollowing the release of a government lake sediment survey (Butler and Davenport, 1980), which indicated anomalous concentrations of metals in southwest Newfoundland, geologists with Utah Mines Ltd. discovered the Isle aux Morts Prospect, a Zn-Pb-Cu-Ba-Ag showing, located approximately 15 km northeast of Port aux Basques (Figs. I and 2). The mineralization occurs in quartz-muscovite schist and is the first significant basemetal discovery in the Port aux Basques Complex."

Jan 1, 1988

By J. Jonas, J. M. Harrington, K. Wangerud, S. D. Fundingsland, J. G. Harrington

EPA NRMRL Mine Waste Technology Program and Region VIII Superfund office are jointly conducting an in-situ technology demonstration at the Anchor Hill Pit Lake, Gilt Edge Mine Superfund site. The goal is to develop in-situ treatment cost/performance data for potential application in long-term water treatment/management at Gilt Edge and similar sites. The pit contained 77,000,000 gallons of pH 3water with elevated metals, sulfate, and nitrate. The Green World Science® patented process for in situ treatment was implemented to isolate and sequester metals; create stable long-term water quality and restore a sustainable ecosystem. COCs have decreased more than 99%, and dissolved discharge standards were attained.

Jan 1, 2004

By Robert H. Lambeth

There are no identified mineral resources in the Italian Peak RARE II areas, and there are no producing or developing mines within or adjacent to the study area. Several prospects are in RARE II area M-4945, Idaho, but none were found in the area I-1945, Montana. The Viola Mine (fig. 1, no. 15) vicinity and the Heart Mountain vicinity along the west and south borders, respectively, are being prospected. There has been no recorded production from mines within the study area, but between $2.5 million and $5.0 million worth of lead, silver, and zinc were produced in the adjacent Birch Creek district - dominantly from the Viola Mine - from 1882 to 1889 (Anderson and Wagner, 1944, p. 14). The Viola and other mines in that district are possibly, on basin-margin, carbonate-hosted, lead-silver-zinc deposits stratabound within the Devonian Jefferson Formation. Previous studies have considered them to be hydrothermal, replacement orebodies. Mineral occurrences in the Heart Mountain area are possibly black-shale hosted uranium-vanadium deposits in the Mississippian-Devonian McGowan Creek Formation or perhaps the underlying Devonian Three Forks Formation. The Jefferson and McGowan Creek Formations underlie many scattered segments of the study area. The deposits and occurrence; are not sufficiently exposed to determine tonnage and grade, but sampling indicated moderate resource potential at two properties just outside the study area, the Viola Mine and the Elkhorn Group (fig. 1, no. 33). Local residents indicated there are several thousand tons of zinc-bearing resource; at the Viola line. A 23-ft (70-m) drill hole intercept near Heart Mountain et the Elkhorn Group adjacent to the stuny area contained 0.15 percent uranium oxide

Jan 1, 1983