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By Jennifer B. Leinart

Sixty percent of the mines responding to the sixth annual Mining Cost Service labor survey reported increases in wages averaging 3.4% over the preceding 12 months. Only one mine reported a decrease in wages and this was accompanied by initiation of a substantial profit-sharing plan. Thirty-nine percent reported no change in wages. Thirty-seven percent reported using some form of incentive bonus plan. Mining Cost Service annually surveys coal, metal, and industrial mineral mines throughout the United States. Information about wages, benefits, and incentive bonus plans is part of an extensive data collection program to monitor cost areas of significance to the mining industry. This year, 131 mines responded to the survey. The data is collected by sending questionnaires to personnel managers at active mining operations. The information included in this article was taken from the returned forms, from labor contracts provided by some of the mines, and from followup telephone calls. This year's data was collected between November 1988 and February 1989.

Jan 1, 1990

ALTHOUGH the development of the various flotation processes during the last 8 years has been so revolutionary, this development has been, until recently, entirely confined to the separation of the gangue from the mixed metalliferous sulphides.The desirability of finding some method of separating the independent sulphides from such a miXture, by means of flotation, has long been recognized. ThIS need was emphasized when the slimes resulting from the grinding of Broken Hill sulphide ores were for the first time successfully dealt with by the Mineral Separation Company's process on the Central mine. This process proved the practicability of separating the sulphides of lead and zinc as a mixed concentrate from the gangue present in slime. Although this was a very notable achievement, the process has not been generally used, owing to the mixed lead and zinc concentrates resulting from the treatment being acceptable neither to the zinc nor the lead smelters.Although the introduction of eucalyptus oil in minute quantities as an emulsifying agent has simplified the work of the subsequent tabling of mixed sulphide concentrates, rendering unnecessary the burning off or removal of the oil, there will always be a considerable quantity of slimy product too fine to settle on the moving surface of the concentrating machines, and therefore requiring other means for its division into lead and zinc concentrates.

Jan 1, 1912

By M. Gous

Keywords: Pyrometallurgy, Namakwa Sands, ilmenite, DC arc furnace, titania slag, pig iron Namakwa Sands is a heavy minerals mining and beneficiation business in the Anglo Base Metals Division, and operates along the West Coast of South Africa. The business encompasses mining, mineral concentration, separation, and smelting operations. The smelting process comprises the carbonaceous reduction of ilmenite to produce titania slag with a TiO2 content of 86%, and iron with a carbon content of 2.5%. The Namakwa Sands smelter, situated near the Saldanha Bay harbour, commenced smelting operations in 1994, when a 25 MW DC arc furnace was commissioned. The smelting operations were expanded in 1999, with the commissioning of a second 35 MW DC arc furnace. Despite the fact that ilmenite smelting poses a technical challenge in terms of the high temperatures required, the physical characteristics of the slag, the constraints placed on the feedstock, and the tight product specifications, Namakwa Sands has continually increased slag production since 1995. High furnace feed-on utilisation and furnace stability, complemented by continuous improvement drives, will be the vehicle to drive performance in the short term, with longer-term performance enhancements due to strategic process development.

Jan 1, 2006

By R. Cotton

"1. INTRODUCTIONTo say that the environment will be a dominant issue in the 1990' s is an understatement. A world-wide ""green revolution"" is taking place not only with the general public and politicians, but in the boardrooms and plant facilities of corporations around the world. There is probably not a plant manager who has not been requested by his corporation to assist in some way on environmental issues by providing advice and strategy, by dealing with customer or community concerns, by considering environmental matters in transactions, by developing new environmental compliance policies and requirements, and so on.There are, in the author's view, three main challenges for the mining industry in the environmental area in the 1990's. This paper will discuss each in turn. The first challenge is the concept of ""sustainable development"". Whatever the meaning of this much-debated phrase, we are rapidly moving beyond the buzzword, and into the specifics. It will clearly impact on the way we manage our companies, our communities and our personal lives.The second is the challenge of personal liability; particularly for officers, directors, supervisors and managers of the corporation. For example, in Ontario today, a good percentage of prosecutions for pollution offences are against individuals, usually managers and supervisors, in addition to the prosecutions against the corporation itself for the same offence. In all likelihood, prosecutions will increase in number and will increasingly be directed at individuals. A corporate president has already served a jail term for contempt of court related to his corporation's breach of a court order related to sewer by-law offences. Although the case is on appeal, another president has become the first officer in Canada to be sentenced to jail for violation of an environmental protection statute. Other corporate officers and directors have recently been charged with breach of their duty under Ontario's Environmental Protection Act."

Jan 1, 1991

By J Deen, P Sterk, W Forsyth

Homestake Mining Company has made a firm commitment to develop a functional and cost effective perimeter blasting program. The goal of the program is to develop smooth, sound walls in all development ends. A good perimeter blasting method will improve safety, reduce waste rock handling, allow easier support installation and reduce scaling time. All the benefits will contribute to an overall reduction in total development costs.

Jan 1, 1997

By J. Shang, P. Howarth, B. Morris

Tailings from the nickel refinery in Copper Cliff, Ontario, consist of fine silicates mixed with a variable amount of conductive and magnetic minerals mainly associated with sulphides and iron oxides. Subsequent oxidation of sulphide- rich phases within the tailings results in the formation of an acidic leachate that may contain significant concentrations of trace metals. Mapping the spatial distribution of regions of higher sulphide concentration therefore provides insight into the distribution of the acidgenerating potential within the tailings. Electrical conductivity is constrained by two parameters — the concentration of metallic sulphides and the ionic concentration of acid in groundwater. Magnetic susceptibility is directly related to the pyrrhotite and magnetite content. It is proposed that combining information derived from airborne electromagnetic and magnetic surveys can provide an indication of metallic sulphide distribution. Preliminary investigations of airborne electromagnetic and magnetic data acquired concurrently over the sulphide-rich Copper Cliff tailings site reveal that these parameters can provide information on mine tailing extent and permit separation of tailings with varying compositional and alteration levels. Airborne geophysical data provide information about the subsurface while a digital elevation model (DEM) and hyperspectral imagery record surface conditions. Integration of the two data sets can reduce ambiguity when interpreting mine tailing distributions and their subsequent alterations.

Jan 1, 2001

By William R. Yernberg

A conference on coalbed and coal mine methane was held March 27 and 28, 2000, in Denver, CO. The conference, organized by the Strategic Resource Institute, was attended by leaders in the coal mining and gas energy industry. The conference focused on the recovery of methane from coal beds as an energy resource and the removal and utilization of coal-mine methane (CMM) related to underground coal mining. The two-day conference discussed methane resources around the world, methods of recovery, methane markets, underground coal mining, health and safety issues and environmental issues related to methane. The consensus among the presenters is that the future looks promising for coal bed methane (CBM) and CMM.

Jan 1, 2000

By W. T. Malone, J. R. Williams, R. L. Tiner, J. M. Tinsley

Hydraulic fracturing methods for production stimulation have become a common procedure in the oil and gas industry. Fracturing treatments are performed on wells of various potentials to help increase the production rate. In addition to the desire for increased production is the need to predict what increase might be expected. This knowledge is useful in economical treatment planning to accomplish the desired production goals for the well. Theoretical production increases due to horizontal radial fractures may be calculated using equations developed from mathematical analyses and electrical models.1,2,6 It also is possible to predict theoretical production increases due to vertical fractures using curves developed from electrical3 and mathematical models.8 However, these studies assumed that the vertical fracture height and the formation height were equal, which may not be true." In addition, the final fracture height through which fluid is produced may not be equal to the created height. The development of vertical fracture proppant transport relationships has made unrealistic the assumption that propped fracture height is equal to created fracture height. Through the use of published proppant transport equations,4'12 it is possible to calculate the height of a bed of propping agent deposited in a fracture of a given height. Assuming that the fluid flowing in the fracture moves through only the propped portion of that fracture (i.e., that the un-propped part of the fracture heals) it becomes essential to know how production increase varies with the ratio of propped fracture height to formation height. It should be recognized that future investigation may determine that the fracture does not heal completely and that a highly permeable channel exists over the deposited bed of proppant. The effect of this channel was not considered for the present study. The following analysis of experimental data allowed development of curves to determine theoretical production increases considering fracture height as a variable. Discussion In designing a fracturing stimulation treatment a number of variables must be considered. The size of the treatment, type of proppant used, proppant concentration, treatment fluid properties and well conditions are all factors affecting the dimensions and permeability of the fracture. Production increase due to a vertical fracture is affected by propped length, height, width and permeability of the fracture for a given set of formation conditions. Production increase may be defined as the ratio of production rate after fracturing to the production rate before fracturing at the same pressure differential, pe — pw. The producing rate in an

Jan 1, 1970

By Jose R. Hernandez-Aguilar, Jeet Basi

"The study evaluated the impact on overall circuit metallurgy of improving the performance of the two flotation columns that make up the final Mo cleaning stage in the Cu/Mo separation circuit at Highland Valley Copper mine. The results showed that a key factor to improve the overall circuit metallurgy was to control the size of the bubbles generated in the columns. When a large proportion of small (< 1 mm) bubbles were generated, the production rate of solids-in-concentrate increased by a factor of 4-5 compared to typical production figures without compromising concentrate quality. This increase in concentrate production rate reduced the circulating load in the circuit causing a significant increase of Mo recovery. A statistical analysis of historical production data showed a strong relationship between final concentrate production rate and overall Mo recovery. This relationship along with the results from this study indicated an opportunity to increase the recovery of Mo from 90% (typical) to 94% without downgrading concentrate grade. This 4% increase represents about 14,000 lbs or $500,000 worth of Mo each month at current metal prices.To provide a rational interpretation of the results, this study also examined whether the model of Gorain et al. (1997; 1998; 1999) could explain the increase of Mo recovery seemingly resulting from the decrease of bubble size. The data showed that the model predictions did not agree with the experimental data, i.e., for a given change (decrease) of bubble size, the predictions underestimated significantly the observed recovery increase. An interpretation based on the fundamental analysis of Finch and Dobby (1990) and Hernandez-Aguilar et al. (2005) is proposed to explain the discrepancy between measurements and predictions obtained from Gorain et al.’s model.INTRODUCTIONIt is generally accepted that the size of the bubbles generated in a flotation cell – a concept usually referred to as “bubble size” – has a significant effect on metallurgical performance. However, a significant number of mineral processing practitioners often question, with valid reasons, the practical benefits of implementing process improvement strategies based on controlling bubble size. “Small” bubbles are often considered to be “favourable”, but how small they need to be for a particular case, or how to adjust operating conditions to control a target bubble size, or whether the bubbles need to be smaller in the first place are questions that usually remain unanswered. Two reasons explain this situation."

Jan 1, 2009

By Dennis Molvik, Roberto J. Guardia, Brad Cowles, Rick Andrews, Robert A. Robinson

A 220-meter (m) segment of the Henderson/ ML King Combined Sewer Overflow(CSO) consists of two 1.8-meter-inside diameter (I.D.) pipe-jacked tunnels that pass beneath Interstate-5 and the BNSF and UPRR railroads. A seismic tomography survey was conducted to develop a 3-dimensional profile of the tunnel zone and better define potential obstructions. The tomography was conducted through three 11 cm high-density polyethylene (HDPE) pipes installed in a triangular pattern around the future tunnel alignments using horizontal directional drilling methods. The pipe-jacked tunnels have been successfully completed, thus permitting a comparison between the predicted obstructions and those actually encountered. The top HDPE tomography pipe was also used to monitor settlements with an experimental horizontal profiler above the advancing tunnels during construction and located two areas of ground loss beneath I-5 that were subsequently grouted.

Jan 1, 2005

By Lawrence H. Van Vlack, Alfred S. Keh

The distribution of sulfur in iron was found to be dependent upon the time and temperature of the treatment as well as the chemical composition of the sulfide. With higher temperatures, the sulfide phase spreads more extensively between the iron grains. A complete network, however, does not form until approximately 1300°C (2372°F), ot which temperature the dihedral angle approaches zero. Silicon has little effect on this change. Aluminum, oxygen, and manganese all modify the temperature of sulfide network formation to a higher value. The microstructures which result and have significance in relation to hot-shortness are discussed. SULFIDE inclusions in steel were recognized by metallurgists before the turn of the century. Considerable attention has been paid to them, and numerous studies have been made on the working properties of steel as affected by them. It has been suggested that ho t-shortness of steel is due to the presence of an enveloping liquid sulfide film at the grain boundaries of the steel in the range of the hot-working temperatures. However, several facts have been observed in commercial steels which do not seem to be completely consistent with this explanation: 1) the frequent absence of continuous films of sulfide as observed under the microscope, 2) the absence of hot-shortness in some high sulfur and resulfurized steels, and 3) the limitation of hot-shortness to a definite temperature range. The role that manganese plays in steel to eliminate hot-shortness is well known, but the theory behind it is still under question. Moreover, the effect of de-oxidizers such as aluminum and silicon, and the effect of oxygen are still not clearly known. In this study, the effect of heat treatments and of additions of manganese, aluminum, silicon, and oxygen upon the distribution of sulfide inclusions in iron was investigated. Both the as-cast and the heat treated structures were studied, using microscopic and autoradiographic techniques. Part of the results were interpreted in terms of Smith&apos;s&apos; concept of microstructure. Review of Literature Metallurgists used to consider sulfide inclusions as suspended particles. It was Wohrman&apos; who first pointed out that sulfide inclusions are soluble in liquid iron. Many observed facts may be understood on the basis of this concept of solubility. Wohrman found that small castings contain small inclusions. and larger castings contain larger ones. Also, inclusion sizes are smaller near the chilled surface. For the same size ingot, the average inclusion size in a given heat of steel depends upon the rate of solidification. That is, with slow solidification, enough time for precipitation and agglomeration of these

Jan 1, 1957

By Jason Ryan, Stephen Harria

Q.E.D. (QED) is a blast design and evaluation model that allows full three-dimensional design specification including the development of unique “live” terrains and an unlimited variety of complex charge configurations. QED’s analysis package allows the examination of likely outcomes resulting from changing various design variables in terms of vibration, fragmentation, rock-mass damage and muck-pile profile. Especially applicable to use cautious blasting applications, QED’s damage model uses vibration to estimate rock damage beyond excavation boundaries. This relates directly to operations such as Yucca Mountain Nuclear Waste Repository in Nevada, where damage beyond the excavation perimeter must be tightly controlled. The U.S. Department of Energy (DOE) h as b een studying a site at Yucca Mountain, NV to determine its suitability for long term storage of nuclear waste. The main mechanism of waste isolation will be the natural barrier of the host rock Total Systems Performance Assessment (ISPA) is used to model the excavation design and its behavior over time. Of importance to TSPA is quantifying the condition of the rock-mass before and after excavation. Ideally, there should be no excavation-induced changes to the rock-mass’ structure (removing the requirement to model the effects). At the least it may be possible to keep excavation-induced damage far enough away from waste packages so that modeling of these effects will not be required. QED can calculate a prediction of the extents of blast induced damage to the rock-mass. By using this metric as a design parameter, it may be possible to complete excavation of the repository more rapidly and inexpensively than previously thought, without jeopardizing the structural integrity of the waste containment areas or requiring blast damage to be modeled by the TSPA. This paper will explain the structure of the QED blast modeling system and show the analysis of historical data from Yucca Mountain. Processing of the historical data and the subsequent results will demonstrate how blast modeling can be used on an ongoing basis to assist the excavation process at Yucca Mountain.

Jan 1, 2000

By Thomas Varley

During the past few years, since flotation has become the paramount treatment method for most all kinds of ores, the Bureau has gathered the data on consumption of reagents used in the flotation treatment. The first report was issued in 1916. A brief review of such reports snows the progress made in the art of flotation, and each year brings forth the development of new reagent a or combinations of reagents that seem sure to survive, but research and progress spell their defeat, if not by entire elimination, at least subjects them to considerable modification.

Jan 1, 1928

By P. Turcotte, E. Karampinos, F. Mercier-Langevin

In some underground hard-rock mines, squeezing compressive ground conditions are influenced by the presence of rock foliation and high stress. In these cases, the orientation of the foliation with respect to the drift direction has a considerable impact on the magnitude of the resulting deformation. Irrespective of the reinforcement and support strategy, keeping drives developed sub-parallel to the rock foliation operational is difficult, and often requires excessive rehabilitation during the lifetime of the excavation. This study uses field observations and convergence measurements at the LaRonde and Lapa mines of Agnico Eagle Mines Ltd to provide guidelines of the anticipated squeezing levels at these operations.

Jan 1, 2015

By Trevor Howie, Mal Edwards

"Thiess Contractors Pty Ltd. designed and operate the Mt Owen Mine in the Hunter Valley of NewSouth Wales, Australia on behalf of the owners of the mine, BHP Coal Pty Ltd. The mine is a multiseam open cut coal operation. Mining by Thiess commenced in September 1996 following thecompletion of the coal preparation plant. The location of the mine is shown below on Figure Al."

Jan 1, 1997

Because of its small interburden thickness, concentrated stress distributions, high coal seam metamorphism, and complex geological conditions, mining the five coal seams (Nos. 5, 7, 8, 9 and 12) of Kaiping coalfield is difficult. Kaiping coalfield is located within 80 m in the Kailuan Group. The overburden caving caused by mining the five coals seams was measured using ZTR12 geological penetration radar (GPR) survey combined with borehole observations. The development characteristics of full-cover rock fractures after mining were obtained from the GPR scan, which provides a measurement basis for the control of rock strata in close multiple-seam coal mining. For the first time, it was found that the overburden caving pattern shows a periodic triangular caved characteristic. Furthermore, it is proposed that an upright triangular collapsed rock pile and an inverted triangular area with larger fragments piled up alternately appear in the lower gob. The research results show that the roof structure formed in the gob area can support the key overlying strata, which is beneficial to ensure the integrity and stability of the upper coal seams in multiple-seam mining of close-coal seams.

Jan 7, 2020

By J Watt

The Hidden Valley Gold Project is located in a remote and mountainous area of the Morobe Province approximately 30 km south of the township of Bulolo and approximately 90 km south-southwest of the provincial capital, Lae. The Hidden Valley deposit was discovered in 1984 with the nearby Hamata and Kaveroi deposits discovered in 1987 and 1992 respectively. Reserves (Harmony, 2009) at these three deposits are 42.1 million tonnes of ore containing approximately 2.9 million ounces of gold and 45 million ounces of silver. A further 5.4 million ounces of gold and 84 million ounces of silver are in the resources category. The process plant is designed to treat 4.2 million tonnes per year of gold/silver ore extracted by open cut mining methods. Ore is classified into three ore types according to oxidation state: oxide, transition and primary. The silver to gold grade ratio is high for the Hidden Valley and Kaveroi ores, generally in the range 15 - 20:1, and much lower for Hamata, typically 1 - 2:1: Primary ore is the dominant ore type at Hidden Valley with sulfur grades up to about two per cent sulfur. Oxide and transition ores are more prevalent at the Hamata deposit, but its primary ore has up to five per cent sulfur grades. Variable ore types, particularly in the initial years of operation, high silver to gold ratios and limited plant site area, due to the challenging terrain, present the main processing challenges for this project. This paper describes the operating strategies and process development for the main areas of this circuit, highlighting selections of processes and equipment that achieve cost effective, yet flexible solutions to the treatment of ores from these deposits.

Jan 1, 2009

By Ingrid Hann

The Triple Bottom Line ? Economic Sustainability ? Creation of Joint Venture companies ? Planned evaluation of other kimberlites ? Social Sustainability ? Impact Benefit Agreement and Participation Agreements ? Education and training initiatives ? Environmental Sustainability ? Environmental management ? Mine closure planning

May 1, 2008

Validation and Simulation of Optimised Compressive Crushing Ores and aggregates are used in countless applications all around in the society. The frequent and escalating usage of these natural resources requires efforts aimed at not only making do with what is available, but also undertaking actions to improve the production yield and the processes involved. This strive to improve the performance and efficiency of existing crushers and crushing processes has brought about research concerning optimisation of crushing plants as well as theoretical optimisation of crushing. Previous work shows that different applications and different materials require different compressive crushing in order to accomplish a theoretically optimal size distribution. These optimisation results, obtained by genetic evolutionary algorithms and evaluated with so called fitness functions, convey the theoretically optimal number of compressions and their corresponding compression ratios. Presented in this paper are thus some laboratory crushing tests, which are conducted in order to validate a set of previously optimised crushing sequences. More specifically, interparticle crushing sequences are carried out in a Piston-die testing equipment, where samples are sieved between each compression. The subsequent analysis of these results shows good correlation with model predictions, which combined with a comparative study between presented optimisation results and measured data from a real crusher indicate a significant potential for improvement. However, before redesigning crushers according to what is theoretically optimal, the resulting impact as well as the effects on the outcome of a crushing plant must be examined. Crushing plant simulations using the software PlantDesigner« are consequently performed. Models of existing crushers are altered, resulting in changed particle size distributions from some of the crushers in a crushing plant. Thence, it is concluded that significant gains can be made in terms of capacity, process yield and energy consumption.

Sep 13, 2010

By Bruce Cavender

Historically, the processing function has been regarded as efficiently managed as long as production costs were kept low, recovery was adequate and sufficient plant capacity was avail-able. In this paradigm, processing is viewed as capable of making only a limited contribution to a company?s competitive advantage. However, the processing function can provide a primary vehicle for building critical competitive capabilities. Processing organizations should be encouraged to become so accomplished they generate new opportunities for other functional groups and thereby influence a company?s overall strategy. This requires a deep shift in processing?s role, in its self-image and in the expectations of it held by managers in other functions. Specific plant improvement techniques ? total productive maintenance (TPM), loss control, etc. ? should be viewed primarily as means for building strategically valuable processing capabilities. Different improvement strategies create different kinds of capabilities and present new strategic options. Broadly speaking, a mineral-producing company seeks competitive advantage through two principal activities: the development of new mineral production and reserves and the optimization of existing operations. These lead to increases in ore reserves, production levels and cash flows that are manifested in increased profitability and, hopefully, increases in the price of the firm?s stock. The profitability of a minerals company is a function of the overall profitability of the industry sector in which the company participates and the firm?s competitive position within that sector relative to those of its competitors. Competitive advantage within the industry comes from two sources: the ability to maintain lower prices than competitors for the same product (cost leadership), or from the sale of products with unique properties that justify higher prices (product differentiation; Porter, 1980). Most mineral companies produce fungible commodities that are sold to anonymous customers, and sustainable cost advantage is the only long-run strategy available to these companies to enhance profitability.

Jan 1, 2008