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By Ulrich Paschedag

The WESTFALIA group of companies developer and manufactures underground mining machinery for complete high-performance longwalls. WESTFALIA uses a state of the art electrohydraulic system as the most important component for the realisation of today's fully automated plow or shearer longwall. The shield control unit (SCU) allows maximum custom designed software flexiblity as well as maximum hardware reliability. The master control unit (MCU) monitors shield support data as well as the plow/shearer position. By using an industry standard PC in an explosion-proof box with an intransically safe keyboard nearly unlimited software capabilities can be obtained with inexpensive hardware. Among various other modes of operation this MCU allows the monitoring and recording of data which can be transmitted to a surface computer. Production and operational adjustments can be made by the mine management based on the MCU information. Statistical analysis of the distribution of roof pressure under various conditions is also possible. The WESTFALIA automation system PM-4 gives the operator maximum flexibility and helps the mine management to run their longwall more efficiently and safely.

Jan 1, 1994

The effect of microwave radiation on the processing of Palabora open pit ore has been investigated. Significant reductions in Bond work index are demonstrated for microwave treated samples. Reductions in work index were found to be sensitive to applied power level and method of application. After single stage magnetic separation tests, improvements in recovery of FeO were noted. However, these were curtailed by oxidation of the magnetite species as a result of continued heating. The effects of microwave radiation upon the recovery of copper after froth flotation were also quantified. Small initial increases in recovery of copper were note dafter microwave treatment. However, with prolonged exposure, recovery was found to decrease. Overall recovery of copper was not affected except for samples treated for extended duration. The influence of microwave treatment upon the conventional Palabora grinding circuit has been quantified with the use of USIMPAC software. Conclusions are made regarding the economics of microwave treatment for this ore. Keywords : Microwave; Grinding; Magnetic Separation; Flotation; Economic Analysis

Jan 1, 2000

By R L. Brathwaite

The gold-scheelite-quartz lodes of the Wakamarina valley were the most productive of the mesothermal gold-bearing areas in the Marlborough Schist. Most of the production came from the Empire City and Golden Bar mines which worked the Golden Bar lode. Only 134 m of its 1800 m strike length are accessible, in the No.2 level of the Golden Bar Mine. A fault has downthrown the Golden Bar Mine section by = 47 m and displaced it left-laterally by 18 m. The lode is a typical ribbon-banded mesothermal vein, averaging c. 1.75 m wide, and enclosing narrow horses of schist country rock. It is composed of bands of milky æbuckÆ quartz with thin laminae of schist. Scheelite occurs in short strings of grains within quartz on the footwall side of the lode and also in small quartz-carbonate veinlets in the foot wall and hanging wall schist. The lode quartz contains only localised traces of pyrite and arsenopyrite. They are more abundant in the wall-rock schist.   The Golden Bar lode lies within a steeply dipping normal fault, which, on its footwall side, is adjacent to a 40 m-wide, shallow-dipping mylonite shear zone. Within 1 m of the lode, the shear foliation has been dragged down to nearly parallel the lode footwall. Wall rock alteration is manifested by a marked increase in K and Rb, which correlate with abundant illite/muscovite and K-feldspar within 2 m of the footwall of the lode. Amphibole, stilpnomelane, and pumpellyite show a progressive decrease towards the lode. As and Sb increase close to the lode, but are at background levels within the lode itself. Enhanced Cr (150-430 ppm) in the quartz, relative to the schists (~40 ppm), suggests that the source hydrothermal fluids passed through and leached mafic rocks, such as the metabasites from the hanging wall of the lode (~400 ppm Cr).

Jan 1, 1995

By Reid K. J, Restarick C. J

The breakage and flow characteristics of quartz, ground as a minor constituent with calcite in a continuous wet ball mill, have been determined by carefully controlled grinding tests.A mathematical model, combining the simple functions which describe these characteristics, has been used to predict both steady state and non steady state results.The calculated results are compared with experimental data.

Jan 1, 1966

By B. W. Gandrud

[The Bureau of Mines is conducting an extensive investigation of coal preparation in the Alabama coal fields in cooperation with the University of Alabama and coal-mine operators. In this investigation the drainage characteristics of typical coals from the Warrior and Cahaba n fields were studied. Tire main purposes of this study has been to evaluate no nearly as possible relative influences of certain factors on rate of drainage and to determine whether the drainage characteristics of coals from different beds or from different mines on the soma bed differ materially. A further objective was the development of a laboratory drainage test that would predict approximately the rate at which any coal will drain after having been loaded into a railroad car in a saturated condition. The study has been confined to samples of slack coals - that is, coals from which none of the fine sizes have been removed. The samples ranged in upper size limits from 7/16 inch to 3 inches. It did not seem necessary to study nut and egg sizes, that is, sizes from which the fine coal has been removed by screening, as these lose water so rapidly by natural drainage that they present no serious problem in dewatering after treatment in a washer. The significance of drainage characteristics of Alabama coals is apparent in view of the fact that not less than 70 percent of Alabama?s total coal product is subjected to wet washing before being materials.]

Jan 1, 1941

The New Zealand microcontinent is relatively well endowed with gold deposits; its past gold production per unit area of 3.2 kg/km2 ranks high on a world scale. Total recorded production (1857 - 1986) is about 854 000 kg and most of this gold was mined between 1861 and 1920. There has been a strong revival in gold exploration and mining since 1979, with exploration expenditure of around $15 million per annum and a declared gold production in 1986 of 1265 kg (886 kg in 1985). In addition to numerous alluvial gold recovery plants working small to medium sized deposits (mainly in Westland and Otago), there are five medium to large projects that have started production (Martha Hill), or have reached advanced stages of construction (Grey River dredge), permitting (Golden Cross and Macraes) or exploration (Globe-Progress). This summary paper is taken from reviews by Brathwaite et al (1986) and Brathwaite (1988).

Jan 1, 1988

By E. H. Rose

This paper, describing the concentrator practice of the Moctezuma Copper Co., is one of a series being prepared by the Bureau of Mines. The Nacozari concentrator of the Moctezuma Copper Co. (the Mexican subsidiary of the Phelps Dodge Corporation) is located about 75 miles south of Douglas, Ariz., in the Moctezuma District of the State of Sonora. Nacozari is the southern terminus of the Nacozari Railroad, ever which all concentrate is transported to Douglas for smelting.

Jan 1, 1930

By D. Scott Scovira, Thomas Gustavsson

Exiting WW2, the potential of nitrates and hydrogen peroxide for application as industrial explosives both became known. The technology stream advanced the development and uptake of nitrate-based explosives to the point that they are the current global standard for blasting. Recently environmental issues are influencing the strategic agenda of extractive industries. The mid-2010s saw renewed interest in hydrogen peroxide explosives to eliminate NOx fume. Carbon reduction initiatives in the 2020s provided additional impetus to investigate hydrogen peroxide-based explosives. Hypex Bio is at the forefront of developing and delivering bulk gas sensitized Hydrogen Peroxide Emulsion (HPE) for blasting. HPE consists of hydrogen peroxide along with smaller amounts of fuel and emulsifier. The consistency of HPE is similar to industry- standard nitrate-based emulsions. It is compatible with existing priming and initiation systems. HPE does not contain nitrates and thereby does not produce post blast nitrous oxide fumes nor discharge of nitrates or ammonia to mine water. Importantly, HPE contributes to reduction in total carbon emissions as compared to nitrate-based explosives.

Feb 1, 2025

By D Thorburn

This paper reviews the history of environmental assessment in New Zealand with reference to mineral developments. Emphasis is given to larger more controversial projects particularly metal mines. The changing role and application of the Environmental Protection and Enhancement Procedures is examined in the context of changes in the government's environmental administration and the response of the Ministry of Energy's resource allocation group. Conclusions are drawn on the effectiveness of the present environmental assessment activities and on the allocation of administration of priorities in the Ministry. The Ministry of Energy has effectively ceased to exist.

Jan 1, 1990

By Chris Bennett, Glen Kosick

"Process modeling and equipment sizing procedures for SAG circuits has advanced significantly over the past two decades. However, no matter how exact the hardness tests, models and scale-up calculations, if the ore samples being used for design do not accurately represent the orebody then major design errors can be encountered. This paper will describe a hardness testing method for identiQing the power requirement profile of an orebody, to an extent that design errors due to poor sampling can be greatly reduced or avoided altogether. It will provide some insight into the magnitude of hardness variability that can be encountered in an orebody. Finally, the paper will preview how detailed hardness distribution data can be incorporated into mine block models, to optimize SAG circuit design for an orebody, both fi-om a capital investment and throughput point of view.INTRODUCTIONIt has long been known that many SAG/AG' circuits experience wide swings in throughput. These throughput variations are almost always of a magnitude not anticipated in the plant design; consequently, they are detrimental to the expected return on investment for the mining companies. It is clear that the throughput swings are mainly caused by changes in ore hardness. In 1993, in an attempt to address this problem, MinnovEX began investigating the possibility of using a small scale SAG test (2 kg charge) to predict SAG power requirements from drill core samples. The objectives of the small scale test were to enable mining companies to do many more SAG hardness tests than currently undertaken for a particular orebody. To make this possible, the SAG tests had to use a minimal amount of sample, be cost effective, and give acceptable accuracy in the prediction of SAG power. If this small scale SAG test proved accurate, then the high sampling frequency would yield results that approach the true hardness distribution of an orebody. This hardness distribution could then be used to derive the distribution and variability of specific energy required throughout the complete orebody. This specific energy (kWh/t) can be thought of as the power required to grind one tonne of ore per hour (kW/tph) to a specified size. Once the true distribution of power requirement throughout the whole orebody is understood, the grinding circuit design team can make an informed decision regarding the hardness value that is most appropriate for sizing the SAG equipment. Throughput losses due to hardness variation could be deliberately planned for or avoided altogether (a capital cost decision)."

Jan 1, 1999

By Wilbur I. Duvall

This report presents experimental data on crater formation in four rock types. From an analysis of these data a general theory of rock breakage by explosives is deduced. This theory accounts for most of the rock breakage and other phenomena that occur when a concentrated charge is detonated in a drill hole near a free surface. From instrumented crater tests and high-speed motion pictures of the explosions, various experimental checks on the deduced theory of rock breakage are made. The general mechanism of rock breakage by explosives as described in this report is outlined briefly below. The detonation of the explosive charge creates a high gas pressure in the charge hole, which in turn generates a compressive strain pulse in the surrounding rock. This compressive strain pulse travels outward in all directions from the charge hole. Near the charge hole the amplitude of this strain pulse is sufficient to cause crushing of the rock. However, as the strain pulse travels outward its amplitude decays rapidly until no further crushing of the rock is possible. The compressive strain pulse continues to travel outward until it is reflected by a free surface. Upon reflection the compressive strain pulse becomes a tensile strain pulse. As the strength of rock in tension is much less than in compression, the reflected tensile strain pulse is able to break the rock in tension, progressing from the free surface back toward the shot point. In other words, the rock is pulled apart, not pushed apart.

Jan 1, 1957

By F. A. Rutledge

[An a part of the United States Department of the interior program for the development and use of Alaska raw materials, the Bureau of Mines is conducting an investigation of deposits of nonmetallic minerals accessible to the Alaska Railroad for use in building; materials is In the Alaska Railroad-belt area. The results of the investigations, to date, indices that raw materials for the preduction of brick products are in plentiful supply as cloy in the Anchorage area, as fire clay at Sheep Mountain, and as shale in the Healy Creek coal formations near Healy, Alaska.]

Jan 1, 1953

By J. Koster

[Boron is an element whose metallurgical possibilities never have been investigated thoroughly, probably because of the difficulties experienced in the preparation of elemental boron and its intermetallic compounds. The southwestern United States contain the world's s largest deposits of boron minerals. In general, the mineral is readily available, and mining costs are not excessive. The most important boron mineral of commerce is borax (sodium tetraborate) however, there are large deposits of colemanite (a mineral having the composition represented by 2CaO 3B2O3 5H2O) in Clark County, Nov. This material was worked in times past by converting it to sodium tetraborate. In recent years the deposits have laid idle because of a mire readily available source of borax in the old lake beds of California.]

Jan 1, 1940

By J. G. Donaldson

Optimum conditions are given for chloridizing pyrite, marcasite, chalcopyrite, arsenopyrite, stibnite, and covellite with chlorine gas. The formation of metal chlorides is affected by the time and temperature of chloridizing, and by particle size of the sample. Chloridizing data also are given for chemically precipitated antimony (III) sulfide and copper (II) sulfide.

Jan 1, 1962

By Monique Pharand, Jeet Basi, Simon Hille

"High quality activated carbon is essential in the recovery of gold in Carbon-in-Leach (CIL), Carbon-in-Pulp (CIP), and Carbon-in-Column (CIC) circuits. Goldcorp’s Campbell complex at Red Lake Gold Mines (RLGM) experienced a period of low soluble gold (Au) recoveries during Q3 2013, during which time the processing plant saw higher than typical Au grades in the CIP tails solution stream. A technical review identified that the CIP circuit may be experiencing a carbon-fouling issue. To further understand the degree of fouling, and to troubleshoot the low recovery problem, samples of carbon were collected from the CIP, elution, acid wash, and regeneration circuits, and submitted for characterization test work. This paper summarizes the steps taken to remedy the carbon-fouling problem at RLGM resulting in increased overall Au recovery.Overview of Red Lake Gold MinesRed Lake Gold Mines is located approximately 450 kilometres northeast of Winnipeg, Manitoba, in Ontario’s western boundary region.All mining is carried out through underground operations, utilizing overhand cut and fill, underhand cut and fill, and long-hole mining methods. Ore types include: silica-replaced carbonate veins with free milling gold, siliceous replacement-type mineralization (rich with arsenopyrite) marginal to veins, broad disseminated sulphide mineralization along major shears, and some minor sulphidized chemical sediment-hosted ore. The operation is supported by two milling complexes: Red Lake, and Campbell.Process DescriptionThe Campbell processing plant's main unit operations consist of grinding, gravity concentrating, flotation, autoclaving, leaching, carbon-in-pulp (CIP), carbon elution and reactivation, electro-winning, bullion smelting/refining and cyanide destruction, and concentrate handling. A schematic of the plant flowsheet is shown in the figure below.BackgroundHigh quality activated carbon is essential in the recovery of gold at many CIP/CIL/CIC processing plants. At RLGM, gold-bearing ore is milled and cyanide is added to leach the gold from the solids into solution. The dissolved gold then comes into contact with activated carbon, and adsorbs onto its highly porous surfaces. Gold is then recovered by separating the activated carbon from the main slurry for further refining. As such, the characteristics and quality of the activated carbon have a significant and direct impact on overall gold recovery."

Jan 1, 2016

By C. J. Badenhorst

The scope of this project was to research, develop and eventually produce a personal occupational hygiene and safety exposure monitor system to assist in recording and analysing various stress factors that could affect the health, wellness and safety of employees, i.e. that could result in injury or ill health of workers, create stress build-up within individual workers that could negatively affect worker alertness and safety, and, may even result in permanent disability or death. Utilized systems at the time were all reactive, whereas the DOHEMS (Proactive Digital Occupational Hygiene and Safety Exposure Monitoring) System enabled the measurement of exposure (and associated risk) in a proactive manner via real-time exposure and digitized recordings. The idea of the development was to create a unit that is so cost effective, small and light that every worker can use a system on a daily basis. The development will eventually replace current, bulky and expensive monitoring equipment. The device must be a portable battery operated device and monitor the immediate working environment by periodic sampling for vibration, noise, toxic gasses (NO/NOX/CO/VOC, etc.), body temperature and heart rate. The samples must be time and date stamped, utilizing a real-time clock (RTC) synchronized with the closest regional secondary time source and related to synchronized real-time video captured samples. These samples are then recorded onto a rugged non volatile storage device with the capacity to store a vast number of samples covering the entire working shift of eight (8) hours plus. The system has been fitted with a clear visual local alarm indication system, indicating any excessive exposures or stresses, for the worker?s supervisor to respond to. This system allows for a pro-active approach. The system is also a wireless system (to the external environment) so as to not affect the mobility of an employee and flameproof to allow for use in explosive environments. Keywords: safety, digital, exposure, monitoring, proactive.

Jan 1, 2010

By H. E. Montgomery

Engineering trends for some years have been toward higher temperatures, both in process work and in steam generation. Progress in design has been dependent upon the development and evaluation of suitable alloys. Elementary knowledge of the limitations of copper-base alloys indicate their unsuitability for the higher ranges of operating temperatures; say, for steam to 950°F. Emphasis upon the more severe conditions perhaps is a reason why more complete evaluations have not been made for copper-base alloys over their range of suitability. However, the few studies made show clearly the need for more accurate evaluations. Some copper-base alloys long looked upon favorably because of superior room-temperature properties are not as desirable as some others perhaps not so "strong" and "hard," as measured by usual acceptance tests. Load-carrying capacity and structural stability arc two important factors. Structural stability as influenced by temperature, by presence of corrosive media, or by the effects of stress itself, frequently is a limiting factor. An early reference to creep properties of the cast copper-base alloys is that of Brown1 (Admiralty gun metal, Cu 87.5, Sn 10.1, Zn 2.3 and Pb 0.08). His tests were similar to present-day stress-rupture tests without measurement of creep elongrttion. Loading was in steps with usually 24 hr. between steps, and continued until failure. He advocated a "useful strength value" of 61/2 tons (I4,560 Ib.) per sq. in. at 572°F. (300°C.). A specimen broken in 1/2 hr. at 572°F. had a strength of 21 tons (26,880 Ib.) per sq. in. The strength values as determined by 1/2-hr. tests and those by the longer stress-rupturc start to differentiate at 392°F. (200°C). This is the temperature at which time at load began to play an important part. Bolton, Price and Hebemann2 give creep curves on 88-10-2 (A.S.T.M. B-60, CU 88, Sn 10, Zn 2) and steam or valve bronze (A.S.T.M. B-6I, Cu 87.50, Sn 6.00, Zn 3.75, Pb 1.70) at 500°F. Direct comparison of the two alloys under 7500 lb. per sq. in. stress showed the steam bronze (A.S.T.M. B-61) superior in creep strength to the 88-10-2 (A.S.T.M. B-60). The steam bronze shows no creep after 700 hr. (1540-hr. test). The 88-10-2 shows a rate of about 7.0 per cent in 100,000 hr. over the last 700 hr. of the test. Creep curves on the steam bronze are also given at the same temperature (500°F.) with loads of 6500 lb. per sq. in. and 8000 lb. per sq. in. These indicate "creep strengths" (creep rate within I per cent in 100,000 hr.) in excess of 8000 lb. per sq, in. for this alloy. It was found that higher percentages of tin are detrimental to creep resistance. This is caused by the presence of or formation during test of considerable alpha-delta eutectoid in the higher tin alloys. Bolton also states that the high

Jan 1, 1945

By J. D. Patsey, G. T. Lineberry

Introduction A computer program was developed for analyzing drum-type hoists before modifying an existing system or designing a new one. Its use permits the preliminary evaluation of a system before seeking technical assistance from mine hoist designers and manufacturers. The user-friendly program accepts a variety of data and analyzes hoisting systems for any balance state. The program can be used to calculate skip capacity to yield a desired production rate, solve for drum face width, select a permissible wire rope, estimate total horsepower of the hoist plant, and estimate annual power cost. Whether required for a large mining complex or for a relatively small operation, a hoisting system must be carefully designed to ensure the efficient, reliable, and safe flow of material. Because shaft sinking and hoist installation can total between 2.5% and 3% of the cost of opening a deep mine, proper hoist selection is critical. Today's mining engineer has at his disposal the most powerful design and analytical aid ever, the microcomputer. There is, unfortunately, limited software for the study of hoisting systems, unlike that for other materials handling equipment (Manula and Albert, 1980; Prelaz et al., 1964; Bucklen, 1969; Thompson, 1985). HOIST reduces a time-consuming set of calculations to a concise package of interrelated subprograms. A literature review revealed no common-user programs to analyze hoisting systems, although at least four major hoist designers/manufacturers/installers have their own in-house programs. To provide a tool with which the mining engineer could preliminarily analyze a materials hoisting system or could check the calculations of a hoist contractor, a computer program was developed. HOIST was written in BASIC for the IBM-PC for ease of program adaptation and to encourage field use on compatible systems. Details of program development are omitted, since the basic principles of hoisting analyses are relatively straightforward, simple, and readily accepted (Harmon, 1973; Nordberg, n.d.; Adler, 1957). Program features, intended usage, and benefits of the computerized solution are emphasized over theory development and mathematical rigor. Background The mine hoist system that is selected and installed at a mine is the "lifeline" of that mine, with installations lasting 20 years or more. Thorough study is warranted to ensure that productivity demands are met at a minimum cost per ton. The increased cost of a large, powerful, high-speed hoist must be offset by increased production to justify its selection. To optimize this tradeoff, an extensive hoisting analysis should be performed. The analyses to properly size the skip (or cage), the drum, and the hoist drive are conducive to computerization, permitting rapid evaluation of changeable operating and design parameters, such as velocity, acceleration, state of balance, and productivity demand. The program is particularly useful in conducting sensitivity trials, such as investigation into the effect of change of productivity on skip capacity and on horsepower of the hoist drive. HOIST is currently limited to the study of drum-type hoists with cylindrical drum(s). However, only minor changes to the program would permit analysis of friction hoists and conical drum configurations. Model development and testing The program is based on accepted equations and physical relationships. Examples of manual calculations formed the basis for decision points and program branching. Data is input in the order that it would be needed if the problems were solved manually. The choices are arranged likewise. HOIST was developed in sections, with manual solutions performed to check program logic. The testing became more rigorous as sections were completed. Output from one section becomes input for following sections, as appropriate. The simplified flow diagram of HOIST is given in Fig. 1.

Jan 2, 1987

By Y Xie, L O’Connor, S C. Dominy

Sheeted vein gold deposits are characterised by multiple subparallel veins and often free milling gold. Variability in gold grade and recovery parameters are enhanced by poorly designed sampling and test work protocols. Poor quality samples generally equate to an enhanced nugget effect. A sample can be described as being representative when it results in acceptable levels of bias and precision. Total sampling variability can be quantified by the relative sampling variance, which measures the total empirical sampling variance influenced by the heterogeneity of the lot being sampled under the current sampling / test work protocol. Effort should be made to minimise the relative sampling variance through Theory of Sampling (TOS) and quality assurance / quality control (QA/QC) application. This contribution reports on a case study that exemplifies how high-quality grade and recovery data can be gained from a well-designed and planned drilling, sampling and test work program, followed by bulk sampling. Results across historical resource drilling, geometallurgical drilling, laboratory assay / test work, geometallurgical modelling and a bulk sampling/pilot processing study are reconciled. A whole core, entire-sample test work protocol was used to acquire fit-for-purpose gold grade and recovery data for inclusion into a Pre Feasibility Study reported in accordance with the JORC Code.CITATION:Dominy, S C, O’Connor, L, Xie, Y and Glass, H J, 2017. Geometallurgical sampling protocol validation by bulk sampling in a sheeted vein gold deposit, in Proceedings Eighth World Conference on Sampling and Blending , pp 185–196 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

The project to reopen the Tasmania Mine has centred around efforts to reopen the Hart Shaft to access the high grade reef remaining below the old workings, which extend down to 457 in. Efforts in 1982 and 1987 were frustrated by unstable clay ground around the shaft, which resulted in significant subsidence of the shaft collar and lining. A successful program has since been implemented to solve the problems, stabilize the collar and recover the upper shaft which had collapsed down to 90 m.

Jan 1, 1989