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By Y. C. Kim

The results from a retrospective study are described in this gaper in which she past development drilling activities were investigated using geostatistics. The purpose of the study was to determine the amount of savings in drilling cost that could have been realized through the optimal placement of sequential drill holes using geostatistics. Out of 144 DDH's that were in place within the study area, the results showed a possible elimination of 34 DDH's without any reduction on the confidence interval of the global reserve estimates. If the incremental savings from one drilling campaign to the next were considered, however, the amount of percentage savings were even greater. Other interesting results from this study were; 1) tangible demonstration of the importance of a proper geologic delineation within the study zone, and 2) the robustness of the obtained experimental variograms from the rather early stage in development drilling.

Jan 1, 1981

By Gary MacDonald

What is the primary function of an impact assessment? Many people at the International Association of Impact Assessment?s (IAIA) annual conference said that it is time to return to the fundamentals and consider the underlying drivers of impact assessments ? human health, safety and security. This fall, managers struggling with those fundamentals will receive extra support when a new course focusing on health and socially responsible security is launched online and in British Columbia, Canada, home to many of the world?s junior miners. Now in its 33rd year, the IAIA conference recently held in Calgary, Canada, typically brings together a range of professionals who work in the impact assessment field, including academics, as well as people conducting applied disciplines, such as social and environmental performance management. It is a chance for people grappling with how to assess impacts from projects (for example, dams, mining and other extractive projects), to compare notes and to talk about developments in how to measure, track and report on them. The comments about returning to fundamentals rose as participants talked about the ongoing and increasingly recognized divergence between three main impact assessment streams: environmental, social and health (EIA, SIA and HIA, respectively). Discussions in sessions and in the corridors included calls for streamlining, for integration, for improvement and sharing of practice ? particularly in the HIA stream, where those deeply engaged in the health discipline questioned how HIAs and their intended outcome of protecting human health can be better integrated into the EIAs or SIAs that dominate the impact assessment realm. EIAs and SIAs have become the main tool, particularly from a permitting perspective for large-scale mines, but seem to leave projects with little real information about what they need to do. Human health is not the only concern re-emerging. Although not reflected at the conference, there appears to be an emerging understanding of the need to link the determinants of health with socially responsible security practices. Companies conducting independent social performance assessments for international financial institutions based on the International Finance Corporation?s Environmental and Social Performance Standards increasingly wrestle with both community health and security issues as extractive companies encounter challenging social environments around the world. Once again, the intended outcome is to better protect human health, including avoiding health impacts from conflict, abuses and violence.

Aug 1, 2013

By Indranil Roy

Gua supergene enriched iron ore deposit from Jharkhand, India has been geostatistically modeled. Population modeling shows a negatively skewed 3-parameter log-normal fit for Fe and positively skewed 3-parameter log-normal fit for Al2O3 and SO2. Semi-variographic studies for Fe indicate spherical function fit using point kriging cross-validation technique with Co=4.06(%)2, C5.11 (%)2, Co+C=9.1 7(%)2 and 'a'=348m. Kriging with 50mx50mx 10m block size at 740mRL led to a global mean kriged estimate of 61.98% and kriging variance of 4.04(%)2 for Fe with central 90% geostatistical confidence limits at 61.39% and 62.24% for that level. This led to an ore inventory at 740mRL as 7.29 million tonnes of ore.

Jan 1, 2002

By H. B. Charmbury

The acid mine drainage problem in Pennsylvania is of continuing and growing interest to the coal mining industry, the state government and the citizenry at large. Approximately one-third of the total volume of mine drainage presently polluting the streams of the Commonwealth originates from active coal operations and two-thirds come from ?abandoned mine discharges.? For this reason the Pennsylvania Department of Mines and Mineral Industries has mounted a significant research and action program seeking solutions to this two-fold problem. The Coal Research Board of the Department has sponsored a wide variety of research projects in an effort to study the treatment of acidic and highly ferruginous mine waters. A review of the published literature on the treatment of mine waters indicated that many laboratory and theoretical studies had been undertaken on various aspects of the coal mine drainage problem, but little applied, developmental, or engineering study had been undertaken. In January of 1964 the Board commenced a rigorous program using state and industry funds in an effort to find a ?least cost? solution or solutions to this vexing problem.

Jan 1, 1967

By Donald G. Foot

The Bureau of Mines, U.S. Department of the Interior, devised a direct flotation method for treating low-grade carnallice (KC1.MgC12. 6H20) and sylvinite (a mixture of KC1 and NaC1) ores characterized by a high content of water-insoluble impurities. The procedure consists of (1) flocculation-depression of the insoluble slimes, (2) decomposition leach (carnallite only), (3) potash rougher, cleaner and recleaner flotation, and (4) final product leaching. The technique eliminates the necessity of removing the water-insoluble slimes by mechanical or flotation desliming. Laboratory results demonstrated that the direct flotation procedure, when compared with conventional techniques, yielded equivalent or improved flotation results with equal or less reagent consumptions. The direct flotation method recovered 81.6% of the solid-phase KC1 from carnallite ore and 79.7% of the KC1 from sylvinite ore in final products containing 60.5% and 60.9% K20, respectively. A flowsheet incorporating the described flotation procedure is presented.

Jan 1, 1981

By E. C. Wilson

The knowledge concerning the lubrication of open gearing for mining machinery has contained many unknowns and at its best has relied to a great degree on a "Rule of Thumb" procedure. It will be within the scope of this paper to explain what we have learned to date and what must be learned in the future. The results in the lubrication of open gearing have spanned the spectrum of unsatisfactory to satisfactory. With the advent of larger mining machinery, we are faced with the necessity of a more thorough knowledge of open gear lubrication. We have avail- able, better steels for the gearing, advanced technology and machinery for cutting proper tooth profiles, and better means of aligning the teeth in the gear train. This has made it possible to transmit more horsepower through the same size gear set than ever before, if we have the proper lubrication to complement the factors previously mentioned. We have set up computer programs which can calculate the data fox the tooth forms, the correct operating center distances, the contact stresses, the bending stresses, and the PVT factor of the gear teeth. This program does not, at the present, have sufficient data available to calculate the type of lubricant which should be used.

Jan 1, 1968

By R. K. Singhal

In an underground coal mining environment, a frictional ignition may be defined as the ignition of an explosive air/ methane/coal dust mixture by mining machinery. As the use of power loading equipment has become more widespread, frictional ignition incidents have increased. There have been many fatalities and injuries from this cause including the death of eleven miners in Sydney coalfield of Nova Scotia, Canada in 1979. This paper reports on the findings of a preliminary study carried out under the auspices of the Coal Research Laboratories, Department of Energy, Mines and Resources Canada. The objective of this study has been to identify a Longwall face cutting system that is inherently safer than the conventional shearer loaders used in Nova Scotia.

Jan 1, 1985

By Hiroyuki Abé

This paper is a review of research and development on geothermal energy extraction in Japan especially on hydraulic fracturing. First recent geothermal developments in Japan are outlined in Part I. An increase in the production rate of geothermal wells may be highly dependent on the geothermal well stimulation technology based on hydraulic fracturing. The hydraulic fracturing technique must be developed also for geothermal energy to be extracted from hot, dry rock masses. In Part II, the research on hydraulic fracturing and field application are reviewed.

Jan 1, 1982

By R. S. Kasper

This paper reviews the procedure used to quantify the conveyor frictional resistance on a 3.9 km (2.4 mile) long overland conveyor belt. Field torque measurements of the three drives were used to help fine tune a computer simulation of the conveyor. This enabled the prediction of the effect on various conveyor components that cold temperatures will have on increasing the throughput tonnage.

Jan 1, 1995

By Ralph L. Merklin

One of the most commonly employed set of calculations in mill design and research is the material balance, known in wet beneficiation plants, as an Ore and Water Balance. For mill designers, the balance is one of the principal requirements in determining the proper size of launders, pipelines, process equipment, etc. In process development, one of the major goals is the establishment of an optimum balance. The usual procedure for calculating a material balance involves a manual technique utilizing reference tables, pre -obtained data, and a slide rule or desk calculator. With these, the engineer must perform a series of calculations which are repetitious in nature and time consuming. Figure I is the flowsheet of the grinding and flotation circuits for a copper concentrator. The initial ore and water balance was calculated manually and required approximately 24 manhours. Later, a number of changes were made in the balance, each of which required an average of 8 manhours.

Jan 1, 1967

By M. J. Laurila

The concentration of low grade iron ores to pellets or sinter fines suitable for blast furnace feed or direct reduction is highly energy intensive and costly in terns of both size reduction and separatory processes. Large equipment with high throughputs are required to make the fine grinds and multi-stage separations economical. Control of these circuits is essential to producing a high grade product. As a result, iron ore concentrators possess some of the more sophisticated instrumentation for process control in the mineral dressing industry. These instruments must characterize flowstreams of up to 8,000 gpm where 80% of the particles are less than 50 µm. The past decade has been one where enormous strides have been made in automated control of iron ore plants. This paper reviews state-of- the-art control systems for crushing, grinding, magnetic separation, froth flotation and sizing/classifying circuits. Trends toward computerization and plant automation in response to a dismal outlook for North American steel production are also examined.

Jan 1, 1984

Australian underground coal mines predominately use the longwall method for coal extraction. In longwall mining at least two parallel roadways known as gateroads are mined to delineate the sides of the longwall block, a longwall installation face is then driven connecting the gateroads to enable the longwall mining equipment to be installed. Roadway development should ideally be ahead of the longwall so that the longwall equipment can be installed into the newly developed panel with minimal delay to coal production. A discrete event model of roadway development can help assess how a particular configuration may perform with high levels of variability and uncertainty in operations. One of the major delays associated with roadway development is caused by the shuttle car due to its cyclic stop-start nature. Shuttle car travelling paths and machine interactions are normally constraint by the mine?s roadway layout and mine safety issues. This paper presents simulations of shuttle car route options which can be considered at the design stage to minimize the cycle time of a shuttle car as part of a general roadway development simulation model developed using 3D Flexsim.

Feb 23, 2014

By Y. J. Wang

The Hardy Cross iterative method is the most popular technique for solving a ventilation network problem with natural air splitting. This method traditionally solves each mesh equation by an approximation during each iteration. Thus, it is interesting from both a theoretical and a computational viewpoint to be able to solve for an exact solution to the mesh equation. Presented in this paper is an algorithm for computing the exact solution to the mesh equation with a variable fan pressure. The algorithm uses signum functions for air quantities to generate an alternative mesh equation in the form of a quadratic equation that has two solutions defined by the well-known quadratic formula. The condition that the derivatives of the alternative and the original equations must be the same provides a basis for the correct choice between the solutions.

Jan 1, 1998

By A. R. Laplante

A test to determine the amount of gravity recoverable gold (GRG) in an ore is described. Typical GRG results are given; an error analysis is detailed; possible uses are discussed. Of the 38 samples tested, the lowest GRG content was found to be 25% (most below 25 11m, or 600 mesh), and the highest 94% (most above 300 11m, or 50 mesh). The average GRG content was 63%, with a standard deviation of 19%. Error analysis shows the test to be reproducible within 5 to 10%, depending on the size distribution and grade of GRG, and the sample extraction protocol. When using the same primary sample, reproducibility improves, 2 to 5%, depending on the amount of gold coarser than 850 11m (20 mesh) and sample weight. The test has been applied to greenfield project and retrofit applications, to determine the suitability of gravity recovery. For existing circuits, it has been coupled with a model of gravity recovery for optimization studies.

Jan 1, 1996

By H. M. Castrantas

Caro's (peroxymonosulfuric) acid has been reported to destroy WAD (weakly acid dissociable) CN-but, until recently, the technology has not been demonstrated in other than a laboratory setting. During the last two years, Caro's acid has been shown to successfully detoxify WAD CN-in tailings at two large North American gold mines. Using on-site FMC generators, Caro's acid reduced the WAD CN-from 40-55 ppm to below 20-35 ppm WAD CN-, the target range for the two mines. The detoxification costs using Caro's acid were less than 50% of the treatment cost of using hydrogen peroxide, the previous oxidant of choice. In addition to the considerable savings in CN-detoxification costs, lower WAD CN-values were achieved and the detoxification time with Caro's acid was greatly reduced compared to hydrogen peroxide.

Jan 1, 1995

By L. Lichty, R Bhappu, R. Rowan, G. Ramadorai

Treatment of refractory gold ores containing arsenic have always presented a major problem in their processing to recover the contained precious metal values. The major difficulties are concerned with lower recoveries, production of hazardous fumes, effluents and residues. Because of'these arsenic related problems, many otherwise economically attractive precious metal deposits and dumps all over the world are not exploited. In recent years, treatment processee for refractory gold ores and concentrates have been explored and a few commercial operations employing roasting or pressure leaching have resulted. Roasting has limitations due to environmental constraints related to off gases. Pressure leaching involving high temperatures (180% to 200%) and pressures (400 psi) is accompanied by high capital and operating costs. An alternate route to roasting for treating pyrite and arsenopyrite ores and concentrates ia the "lime-oxygen hydromet" process carried out at a moderate temperature (100%) and pressure (100 psi). A simplified process for treating such arsenic containing ores and concentrates utilizing low temperature and pressure oxidation is presented. This low cost treatment with compressed air and lime renders arsenic as an inert component in the residue, meeting all the requirements of the EPA Toxicity Test. The precious metal values are then extracted from the autoclaved residue by standard cyanidation. This paper discusses this new development.

Jan 1, 1990

By Y. J. Wang

The Hardy Cross iterative method is the most popular technique for solving a ventilation network problem with natural air splitting. This method tradition-ally solves each mesh equation by an approximation during each iteration. It is thus interesting from both theoretical and computational viewpoints to be able to solve for an exact solution to the mesh equation. Presented in this paper is an algorithm for computing the exact solution to the mesh equation with a variable fan pressure. The algorithm uses signum functions for air quantities to generate an alternative mesh equation in the form of a quadratic equation, which has two solutions defined by the well-known quadratic formula. The condition that the derivatives of the alternative and the original equations must be the same provides a basis for the correct choice between the two solutions.

Jan 1, 1997

By Richard M. Crowell

"As thorough sampling is usually expensive, the cost of a complete job is often unwarranted, and a cheaper approximation must be substituted. The engineer should, however, weigh the situation thoroughly before subscribing to an alternative other than an accurate assay basis on which to build his conclusion." Examination and Valuation of Mineral Property. R. Parks, 1949

Jan 1, 1994

By Roberto Pimentel de Souza

CURD started producing pellets in 1969, with one two-million ton straight grate plant. In the beginning of April '73, the second unit came on stream with an additional capacity of 3 million TPY of pellets. In January '77, the third unit started, bringing the annual capacity to 8 million TPY. For the present year 3 more units, 3 million each, are expected to begin production. CVRD's experience is given about the use of different binders and additives. Over the years several kinds of pellets have been produced to satisfy the market requirements. General quality information is given regarding each.

Jan 1, 1978

By Werner A. Ruemmele, Steven R. Wardwell

INTRODUCTION The first phase of the Los Angeles Metro Rail Project consists of 7.1 km (4.4 miles) of subway and stations running through downtown Los Angeles from Union Station to MacArthur Park. Shank-Ohbayashi has two of the tunnelling contracts on this initial phase: A-171 and A-146. Contract A-171, the Wilshire/Alvarado Line, involves tunnel construction beneath 7th Street from the 7th/Flower Station to the Wilshire/Alvarado Station. The project consists of the excavation and lining of 3000 m (9900 ft) of twin-bore, 6.7 m (22 ft) excavated diameter, 5.5 m (18 ft) finished diameter subway tunnels. Contract A-146, the 5th/Hill to 7th/Flower Tunnels, comprises 1220 m (4000 L.F.) of twin-bore tunnel identical in cross section to the tunnels in Contract A-171. The majority of the excavation on Contract A-171 is beneath city streets in a weak siltstone/claystone bedrock with cover varying between 10 m and 25 m (32 ft and 82 ft) to the street surface. Approaching the 7th/Flower Station some fine-grained alluvium is encountered. The tunnels on both contracts are excavated with an open face digger equipped shield. On Contract A-146 the tunnel alignment is a 305 m radius curve of approximately 550 m (1800 L.F.) length underneath several multi-storied buildings of various construction. Excavation is still ongoing on Contract A-146. The contractor's choice for initial tunnel support on both contracts is a system of precast concrete segments similar to what the contractor had used on 7 miles of tunnel in Phoenix, Arizona, for the Arizona Department of Highways.

Jan 1, 1989