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By Stacey Leichliter

The Cripple Creek and Victor (CC&V) Gold Mine (Cresson Project) (Fig. 1) is undergoing an expansion to extend production to the year 2025. This expansion involves building a high-grade ore mill, another valley leach facility (VLF) for heap leach operations and expanding the overburden storage areas. The current operating pits are progressing downward from the oxide ore into a more sulfide and telluride-rich orebody. There is still oxide ore present in the current pits and planned pits not yet mined. There is an increased need for two recovery processes for these two different types of ore. The key component to this expansion is the high-grade ore mill, which has gravity, flotation and carbon-in-pulp (CIP) circuits. The mill will be the main recovery process for the higher grade, more sulfide/telluride-rich ore. This ore type does not recover well on the heap leach pad due to its refractory nature. Geometallurgy is vital for ore characterization for the two recovery methods. Geometallurgy helps develop indices that are used to predict parameters that influence overall recovery and production, such as hardness, crushability, grindability, pH fluctuations, gravity (coarse) gold, flotability and cyanidability. Using geology and mineralogy along with other analytical data, geometallurgical models are constructed and applied to the resource block model for proper planning and extraction of the gold. Geometallurgy aims to analyze the variability in the different responses to the parameters to help reduce risk (costs) and optimize recovery (profit).

Jan 1, 2013

By MARK J. VANARELLI

Estimating ground-water inflows in rock deep tunnels is critical to the safety of personnel constructing the tunnel and the cost of construction. This paper presents two case studies, including the Chattahoochee and Nancy Creek tunnels, for estimating steady-state ground-water inflows into deep rock tunnels. Statistical methods were applied to packer test data obtained from exploratory borings during geotechnical site investigations, and a semiempirical procedure was used to estimate ground-water inflows. The Chattahoochee and Nancy Creek tunnels are deep rock tunnels that exhibit radial flow conditions. For the radial flow condition, a statistical analysis presented in this paper indicates that the semiempirical procedure works well; however, variations in the procedure and/or an insufficient amount of testing could lead to underestimations of the inflow quantities. Modeling using Monte Carlo simulations was observed to be an effective tool for removing data distribution irregularities and incorporating high-end permeability data to derive reasonable ground-water inflow estimates.

By R. L. Guerguerian

Hydrostatic trunnion bearings were recently provided on large Semi-Autogenous Grinding (SAG) mills driven by wraparound motors assembled on the head to shell flanges. A conventional SAG mill would have a ring gear driven through one or two pinions. The effects of the magnetic air gap forces from this new SAG mill drive arrangement on the performance of the bearing are discussed. A step-by-step systematic analytical de-sign of the hydrostatic trunnion bearing is presented, followed by a discussion of grinding mill erection requirements to conform with the design. A brief comparison with other bearing types and their response to the effects of magnetic air gap forces are also presented.

Jan 1, 1992

By Peter McKenna

Different reefs being extracted from a mine will, in all likelihood, have significantly different semi-variogram models - and these will probably vary from geozone to geozone. As errors of estimation are dependent on the semi- variogram parameters, it follows, if a mine samples all reefs in all sections using the same sampling grid pattern, that estimation errors (or limits of confidence) will not be the same throughout the mine. This may be an undesirable situation! A geostatistical study of the relative merits of alternative sampling arrangements has been carried out by considering different reefs in different sections of a South African gold mine.

Jan 1, 1989

By F. Ysla, M. Mendoza

This proposal, based on the CIEMAN Cajamarca - Hualgayoc initiative, focuses on “Transforming Abandoned Mine Lands’’ We aim to study and assess the feasibility of an innovative rehabilitation method. Contaminated soils will be moved from the upper to the lower site, encapsulated with geosynthetic barriers, and covered with topsoil. The decontaminated upper area will be used for planting trees and large-stemmed plants for hiking and tourism, while the lower encapsulated area will support livestock and short- stemmed crops. This study will evaluate the economic viability and multi-use potential of this technique, promoting sustainable land recovery in Cajamarca, Peru.

Feb 1, 2025

By Eugie Kabwe

The effective employment of a pretensioned bolt within support structures requires an appropriate installation tension as a result of sufficient bolt head/nut preload. In this paper, a load indicator washer (LIW) able to withstand an assigned static loading as well as provide an appropriate pretension is presented. The different LIW breadths are numerically analyzed with ABAQUS finite-element code to estimate deformation when a designated 60 kN preload is applied. The numerical simulation employs the bilinear isotropic hardening constitutive law governed by the von Mises yield criterion. The simulation also considers the nominal temperature of the nut-LIW-rock bolt connection. Therefore, long-term relaxation effect on bolt pretension as a result of stress relaxation is neglected. The compressive force required to achieve the LIW predetermined deformation is the bolt pretension. It is drawn from the simulation results that LIWs with thicknesses of 1.5, 2.0, 3.0, 3.5 and 4.0 mm are completely flattened when subjected to 28, 42.5, 65, 76 and 88 kN preloads, respectively.

By Rees D. Groves

Cement copper is ordinarily converted to marketable metal by processing in a conventional smelter and refinery. Because of rapidly increasing cement copper production and limited excess smelting capacity, other techniques were investigated for preparing marketable copper products. One route was to make copper powder for industrial use. The process scheme employed flotation for rejecting the bulk of the impurities, acid leaching to remove residual iron and aluminum, reduction sintering to eliminate oxygen, and grinding to obtain powder. Another route was to sinter the floated and leached copper into the form of anodes and electrolyze these to yield refined copper cathodes. At a current density of 30 amperes per square foot, power consumption for electrorefining was 185 kwhr per ton of copper. The feasibility of preparing commercial-size anodes by sintering is still to be assessed.

Jan 1, 1970

By Ryan Marsters, Adam Pring

The Rawah Ditch is a mountainous water supply diversion which supplies Larimer County, Colorado with water since 1903. The ditch includes two historic tunnels excavated by drill and blast through a gneissic rock buttress. Both rock tunnels were failing with annual convergence. After a snowshoe-accessed eld investigation, nite element modeling, and an alternatives analysis, a diameter DE pipe was inserted within each tunnel and the annulus lled. The proect was implemented in an Alternative Delivery contract lasting ve months from eld investigation through procurement and construction.

Jun 23, 2024

By Z. T. Bieniawski

The efficient and safe design of room-and-pillar coal mines still remains as one of the pressing problems facing the mining industry in the United States. Although much research has been directed to stability of mine roofs and coal pillars, no generally-accepted design method has been formulated. This paper presents a concise procedure for an improved design of room-and-pillar coal mines. Developed as a result of a three-year research effort, the methodology includes essentially three aspects: (i) determination of stable roof spans; (ii) determination of the strength of coal pillars; and (iii) determination of safety factors for room-and pillar coal mining in the United States. It is shown that the presented approach will lead to a greater recovery of coal by a more economical, yet safe, mining operation. Design charts and tables are presented and a step-by-step design procedure for practical mining engineers is explained. Several examples are included demonstrating the use of the proposed design procedure for room-and-pillar coal mines.

Jan 1, 1983

By Gino Vogt

In mechanized tunnelling operations performance, consumption and safety are main factors for jobsites. One of the most important components effecting these factors, especially in slurry TBM operations, are Slurry Treatment Plants (STPs). Inadequate/ suboptimally dimensioned and designed STPs create bottlenecks for tunnelling operation and jeopardize time schedules and performance. Inefficiently planned STPs could drastically increase consumption figures such as electrical power, bentonite, water and polymers, etc. Inaccurately selected and treated suspension properties can cause a high-risk potential for the whole job. This paper debates the relevant key parameters for STPs from start to finish of a project and its results in influencing factors from the manufacturer´s point of view.

Jun 13, 2021

By Barry D. Simmons

The Millenbach copper-zinc orebody is an ideal Canadian example of a stratabound base metal deposit in volcanic rocks. The mine, operated by Lake Dufault Divison, Falconbridge Copper Ltd. is located five miles north of the city of Noranda in northwestern Quebec. The deposit occurs within an Archean volcanic sequence which forms part of regional acidic volcanic center within the Abitibi greenstone belt. Preproduction ore reserves totalled 2,075,000 tons grading 3.5% copper, 3.6% zinc, 1.1 ounces per ton silver, and 0.02 ounces per ton gold. Stratabound lenses of massive sulphides together with underlying stringer sulphides are closely associated with a dome of quartz-feldspar porphyritic rhyolite approximately 3000 feet below surface. The paper describes the presently known geology of the deposit and includes documentation of sulphide mineralogy and textures as well as sulphide/ host rock relationships. The stratigraphy, petrography and chemistry of the volcanic host rocks are described with emphasis on the alteration intimately associated with the sulphide bodies. Although the volcanic stratigraphy is complex within the mine area, the presence of only low-grade metamorphism and the relative lack of structural deformation allow detailed interpretation of geological history. Presently recognized evidence strongly suggests that the sulphides were deposited at and near sea-floor, by hydrothermal solutions. The dome of porphyritic rhyolite appears to have been the most significant factor controlling sulphide localization.

Jan 1, 1975

By Robert W. Row

The run-of-mine coals in the U.S. being fed to coal cleaning plants have become increasingly finer due to the adoption of modern, mechanized mining methods, and economics are dictating that finer fractions, as well as the coarser fractions, be cleaned. Traditional dewatering methods (vacuum disc filters and centrifuges) are proving inadequate for preparing fine refuse for disposal or fine coal product for downstream handling. The Electric Power Research Institute has been supporting research into the nature and limitations of mechanical dewatering, and novel ways of improving it. The efficiency of various silicone-based chemicals at aiding dewatering was investigated, and it was shown that the final moisture content of hydrophilic coals after vacuum Filtration could be reduced by 1 to 5% with up to 40% increase in filtration rate by addition of one of several of these silicones. EPRI also has an on-going program at its Coal Cleaning Test Facility to investigate the performance of the Larox pressure filter in comparison with that of the disc filter and solid bowl centrifuge. While improvements to the dewatering performance currently being obtained in existing operating plants by such means are achieveable, a fundamental study has shown that, regardless of changes in operating conditions, there may be a limit to the lowest cake moisture content attainable by mechanical dewatering of a given sample of coal fines. Determination of this limit for a specific coal would be useful in designing facilities to dry and handle it.

Jan 1, 1984

By D. R. Nagaraj

Secondary Ion Mass Spectroscopy (SIMS) was used to study adsorption of sulfide collectors such as modified thionocarbamates and thioureas, xanthate, dithiophosphate, and dithiophosphinate, on galena, chalcocite, chalcopyrite, and quartz under flotation related conditions. In the case of the adsorption of modified thiourea on chalcopyrite, chalcocite and Cu-activated quartz, and of dithiophosphinate on galena, SIMS measurements have provided direct evidence for the presence of metal-collector (1:1) complexes on surfaces. In the other systems, only the collector molecular ion and its fragments were detected. The distribution of adsorbed species on the surfaces was obtained by using SIMS in the imaging mode. On chalcopyrite, only the copper-collector complex was found; there was no evidence for iron-collector complex. In the case of quartz, adsorption of selective collectors was observed only after activation by copper ions.

Jan 1, 1996

By Guillermo V. Borquez

The economics of open pit mine design are dictated by three basic elements: cut-off grade, stripping ratio and slope angle. Although these elements are functions of a number of independent parameters, they are interrelated through their influence on the overall economics. The optimum slope angle is the most uncertain element to determine, because rock mass properties are difficult to obtain. However, for preliminary estimation, the slope angle can be determined from the relationship between the probability of failure and the safety factor. The economics of the slope selected will depend on a profit versus risk judgment. In this paper, the author will present an actual case of application of this postulate.

Jan 1, 1977

By Bruce E. Kester

The concurrent observation of the phenomena of alkali-aggregate reaction and development of efficient dust collection systems on rotary kilns made mandatory the process modifications to produce low alkali cements. Such low alkali cements as were available prior to these recent changes were either the rare result of low alkali raw materials, the loss of alkalies with dust loss from the kiln stack, or in some instances by the use of CaC12 in the kiln feed to increase volitalization of the alkalies and their subsequent loss or discard with the normal dust emission from the kiln. The relative slowly soluble nature of natural occurring alkali minerals in cement raw materials as compared to the very soluble nature of the alkali salts as present in cement kiln reaction products, either in clinker or in dust emission led to the development of the water leaching system. Two distinctly different problems of leaching are created by the two major systems of portland cement production, the wet and dry processes. The wet process is characterized by moderate dust loads and concentration of soluble forms of alkali in the dust. Further the return of the leached dust slurry does not materially change the characteristics of kiln feed on reintroduction and subsequently does not materially influence kiln operation. The dry process differs in high levels of dust emission and the presence in the collected dust of large amounts of unreacted kiln feed with its sparingly soluble alkali minerals. In the dry process reintroduction of leached dust slurry changes the dry process to what may be classed as a damp process. This change results in some decrease in kiln capacity and creates conditions of operation which are uncommon to either the wet or dry process.

Jan 1, 1963

By Guoqing Li, Hao Wang, Nailian Hu, Victor Tenorio, Jie Hou

This paper presents an algorithm for optimizing the scheduling of trackless equipment in underground mines. With the shortest working interval and maximum productivity as goals, a genetic algorithm (GA) is used to solve the problem, and obtain the optimal working sequence with the most suitable equipment configuration possible. The input for the proposed method is the number of units and capacity of trackless equipment, the production process, ore amount in stopes, and the distance between stopes. The algorithmis verified using four setups of 5 stopes with 5 cycles, 5 stopes with 15 cycles, 10 stopes with 10 cycles, and 10 stopes with 30 cycles. The solution time of the algorithmis no more than 20 min, which is acceptable for practical applications. The results show that the setup of 10 stopes with 30 cycles is closer to the actual production of the mines, and the optimization model can effectively improve the operation efficiency. In this scenario, the robustness of the optimization is tested by simulating equipment failure events. Under the condition of 8% failure rate, the operation time is extended over 3.21–14.56% than expected, which represents strong robustness. The algorithm can quickly provide a feasible and effective solution for the production scheduling decision of trackless equipment in underground mines.

Aug 12, 2020

By P. O. Ripley

Into this tumultuous twentieth century, every second, two new babies are born. This is 5,412 per hour, and 130,000 per day. Relentlessly, consistently, alarmingly, they add to the more than three billion human beings who already inhabit the earth. Every tick of tier clock brings with it a problem child, the problem of another mouth to feed, another body to clothe, another human being for whom to provide. On the other hand, medical science has achieved a postponement of death, considerably past the period of a few years ago. Thus, life expectancy has been increased and world population has increased accordingly. Darwin (4) writing in 1962, suggests "It is curious how long the world is taking to perceive that we are living in what is a fantastically abnormal period of history, and one which must inevitably end soon, The first warning note of a possible population explosion was given by Malthus in 1799". He suggested that population increases geometrical while production increases only arithmetically and that soon we would not be able to feed the rapidly increasing population.

Jan 1, 1966

By E. Fidler

A recent headline in the Wall Street Journal declared, "trendy management schemes very often fail." Many of the management techniques addressed in the accompanying article are associated with quality management including reengineering, benchmarking, total quality management, and employee empowerment. The article made the point that executives, employees, and customers who are involved in such programs rate the effectiveness of these programs very low, and the programs often fail. Yet, we all know of companies that have made significant advances in their operations using these same quality management practices. Why do a few succeed while many fail? History has shown that the companies that successfully carry out quality management programs have two things in common: 1) Strong leadership committed to the success of the program. 2) A comprehensive plan for carrying out and maintaining the program. Stated another way -the reason many companies fail is the lack of committed leaders and inadequate planning. It is ironic that the title of the Wall Street Journal article is "The Best Laid Plans."

Jan 1, 1994

By L. C. Bartel

Geologic features such as structure (faults, folds, fractures, etc.), water bearing zones, aquifers, pemeability variations, and porosity variations are important for mine planning and in situ energy recovery processes. Features important for planning a mine will be important for planning the recovery of energy by in situ processes. Various geophysical techniques might be used to obtain the necessary geologic information. In this paper, case histories will be discussed of the use of electromagnetic geophysical surveys at a potential underground coal gasification site and a potential tar sand oil recovery site to obtain pertinent geologic information. Results show that the controlled source audio- frequency magnetotelluric technique shows promise for mapping faults and natural fracture systems when there is a sufficient resistivity contrast.

Jan 1, 1982

By David N. Hedges

This paper discusses the actual recovery and installation of a longwall in a bituminous coal mine in Western Pennsylvania. The coal bed mined is in the Lower Freeport seam which averages 42 inches (1.07m) in height locally. Drainage from the mine is approximately 3.5 million gallons of water per day (13.25 million liters per day). This water deteriorates the mines predominately fire clay bottom making it extremely difficult to move equipment. Support removal is accomplished by pulling the 6 ton (5443 kg) shields out under their own hydraulic power and transporting them by track over four miles (6437m) co the next longwall panel. This paper also discusses the changes that will be made to aid in the succeeding longwall recoveries and installations.

Jan 1, 1984