Search Documents

By S. B. Keith

Cerro de Pasco Corporation operates five large base metal mines in Peru having a combined production of some three million tons of ore a year. An integrated complex of concentrators, smelters and refineries produces annually about 25,600 short tons of copper, 48,100 short tons of lead, 60,500 short tons of zinc metal, 102,300 short tons of zinc concentrate, 8,272,000 ounces of silver and substantial amounts of bismuth, cadmium and selenium. Geology plays an important role in these operations. The organization of detail geologic work in and around the Cerro mines was set up by John M. Boutwell in 1918 and a geology department was established in 1920. Growing through the years, the department technical staff now numbers over thirty men and. their work covers all phases of geological investigations. Many outstanding geologists of the past and present, too numerous to name here, have studied and contributed to the knowledge of the deposits and the ever growing list of Cerro "alumni" must rival that of any other mining organization. Numerous papers on the geology of Cerro's mines can be found in the technical literature and several doctoral theses have been presented on Cerro subjects as indicated in the attached bibliography, Specimens of Cerro's ores can be found in museum, college and university collections throughout the world. Yet, as with all mines and mining districts, the geologic knowledge of Cerro's deposits in Peru is being revised and added to constantly. This presentation cannot hope to cover adequately all the phases of the geology and mineralization. For a more complete background and discussion of the mine you are referred to the bibliography. Here I shall outline only briefly the more important geologic features and describe some of the newer developments of recent years The credit for the data presented here belongs to the many geologists who have worked or are now working for Cerro de Pasco Corporation, but I must assume sole responsibility for any omissions or variations in the interpretation of their work.

Jan 1, 1965

By John Newby, Ulf Gwildis, Ken Massé, Guillaume Roux

How to connect an effluent conveyance tunnel to riser shaft and diffuser arms of an outfall system is dictated by the ground conditions, which ideally include rock or soil strata of low permeability. Where such favorable conditions are beyond reach, both the complexity of designing and the risk of constructing this crucial system connection increase disproportionally. This paper describes the considerations that went into the approach of connecting a 5-m-diameter TBM drive with the in-river riser shaft of the Annacis Island WWTP New Outfall System in the highly permeable Fraser River sands at hydrostatic pressures exceeding 3 bar.

Jun 23, 2024

By Wade W. Bristol

The Jerritt Canyon Joint Venture project is located about 80 km (50 miles) north of Elko, NV. It produces approximately 9.3 t/a (300,000 oz/year) of gold. The joint venture is 70% owned by Independence Mining and 30% by Meridian Gold. Independence Mining is the operator. The Jerritt Canyon Joint Venture started operations in 1980 by mining a series of open-pit mines. The discovery of deeper ores during early 1990s made it neccessary for the operation to mine a large portion of its annual production by underground mining methods. Underground production started in 1993 at the West Generator Mine. This was followed by the Murray Mine in late 1994. Two additional underground projects are being developed. Underground mining at Jerritt Canyon is scheduled to produce about 3.9 t (128,000 oz) in 1997.

Jan 1, 1997

By ANDREW HOBERT, Maoming Fan

Low-cost and environmentally friendly green froth flotation modifiers of plant origin, such as guar gum, carboxymethyl cellulose (CMC) and starch, have been used in the flotation of some sulfide and nonsulfide minerals. This paper discusses the fundamentals, current applications and potential new applications of guar gum, CMC and starch in minerals flotation. In this study, improved flotation performance was achieved using some green modifiers in flotation columns.

By T. W. Beck

Drilling into coal mine roof strata to install roof bolts has the potential to release substantial quantities of respirable dust. Due to the proximity of drill holes to the breathing zone of roof bolting personnel, dust escaping the holes and avoiding capture by the dust collection system pose a potential respiratory health risk. Controls are available to complement the typical dry vacuum collection system and minimize harmful exposures during the initial phase of drilling. This paper examines the use of a bit sleeve in combination with a dusthog- type bit to improve dust extraction during the critical initial phase of drilling. A twistedbody drill bit is also evaluated to determine the quantity of dust liberated in comparison with the dust-hog-type bit. Based on the results of our laboratory tests, the bit sleeve may reduce dust emissions by one-half during the initial phase of drilling before the drill bit is fully enclosed by the drill hole. Because collaring is responsible for the largest dust liberations, overall dust emission can also be substantially reduced. The use of a twistedbody bit has minimal improvement on dust capture compared with the commonly used dust-hog-type bit.

Jan 1, 2014

By Keith S. Liddell

he selection of mill design parameters to suit the applica­tion requirements can result in quite different operating parame­ters for each generic type of application, even though the basic mechanical layout of the mills may remain similar. The selection of the type and size of grinding media is very important to efficient and cost-effective operation, and to ensuring that the milled product achieves the required properties. Accordingly, the grinding media selection is seen as an integral part of the mill design. Consideration of the requirement for classification is important in order to achieve the optimum mill and circuit performance. This can lead to the circuit feed not being classified for a steady feed with minimal slimes and a low size reduction ratio. Feed containing on-size particles would be deslimed by open circuit classification. Closed circuit classification is performed where the feed fluctuates. The rheological characteris­tics of the circuit feed slurry can have an influence on mill performance, and needs to be allowed for. A common misconception frequently encountered is the belief that "a mill is just a mill". This is not the case with stirred types of mills, since the operating parameters selected for the mill can have a large effect on the product characteristics. For example, horizontal shaft high speed stirred mills have a com­pletely different grinding action to vertical shaft low to medium speed stirred mills, which results in large differences between the surface area produced at a given product size (Liddell, 1986). Hence, it can be misleading to apply test results or design procedures obtained from one type of mill to other types for scale-up. The Metprotech stirred mill, as applied in the mining and minerals industries, is a low to medium speed vertical shaft mill. The basic design has been discussed previously (Liddell, 1989). Currently, the largest mills that have been manufactured have an installed power of 400 kW. The largest chamber volume at this power is 6000 litres, containing IO t of grinding media. It is intended that the installed power will increase up to lMW as applications requiring larger sizes arise.

Jan 1, 1995

By H. A. von Schonfeldt, H. Douglas Dahl

INTRODUCTION During the past decade, significant pro¬gress has been made in applying rock mechanics principles to mine design problems by a great number of researchers. Some of these new techniques have found their way into the engineering and planning offices of the operating mine. In spite of these advances, however, the application of rock mechanics in the day-to-day mine planning and design of our domestic coal mines is rela¬tively rare. There are a number of reasons responsi¬ble for this relatively slow progress, not the least of which is the question of how to measure the success or cost effectiveness of a sizable rock mechanics effort in an opera¬ting mine. Firstly, the properties of geologic materials generally vary over a wide range and it is, therefore, difficult to assess whether an improvement in the mining conditions is due to a design change or due to a change in the geologic conditions. A second reason for the slow acceptance of rock mechanics in engineering thinking is the fact that some of the concepts are quite difficult and that physical evidence of their validity to mine design is still rare. Thirdly, com¬munication between research, engineering and applications oriented people appears to function only intermittently. In our view, however, the most important impediment lies in the "state-of-the-art." Exactly how much can rock mechanics help the mine operator? The best that rock mechanics can do at present is determine whether one approach is better than another when weighed against some design objective (stress, strain, deformation). We cannot determine the abso¬lute best ground control design -- only what is better. If ground control is lost, the statement that "it's the best one we looked at" means very little to the harried operator. While the "state-of-the art" has advanced a great deal, it has certainly not been reduced to an engineering matter in that design hand¬books are available -- they are not. The success of a rock mechanics program, there¬fore, can be determined only over a long period of time of continuous effort.

Jan 1, 1977

By M. J. Gula

In the solvent extraction -electrowinning recovery of copper from oxide or sulfide ores there is a continuous transfer of iron and other impurities from the primary leach solution to the copper electrowinning electrolyte via chemical transfer or mechanical entrainment. Iron is the principal impurity that has to be controlled in the electrolyte by a "bleeding" of the electrowinning solution. This bleeding transfers copper and sulfuric acid back to the primary leach circuit along with the iron. Copper is recovered via the solvent extraction process and generally the sulfuric acid is used as a reagent in leaching. Unfortunately, cobalt, which is added to the electrowinning solution to modify the anodic process, is irreversibly lost through the bleeding operation. This cobalt loss represents a significant operating cost to SX-EW copper producers. DiphonixTM ion exchange resin contains diphosphonic acid and sulfonic acid functional groups on a polystyrene-divinyl benzene matrix. This resin has been found to strongly and selectively extract ferric ion from copper sulfate -sulfuric acid solutions containing cobalt. Thus, an ion exchange process using DiphonixTM resin for the control of iron has been developed to replace the conventional bleed stream process. The new process minimizes the loss of cobalt from the electrowinning circuit and strips the iron into a sulfate based solution suitable for leach solution makeup. In addition, this process can effect a lowering of the total iron concentration in the electrolyte circuit with an associated increase in current efficiency. In this paper, data on the loading and elution of iron are presented. Laboratory and pilot scale data will be discussed along with information on process design and comparative economics.

Jan 1, 1996

By Irwan Halim, Bhoshaga Mitrran Ravi Chandran, Kevin Huynh

Tunnel segmental lining design constitutes a significant iterative process where modeling and numerical analysis are factors in deciding the number of segments, their dimensions, gasket placements, as well as the locations of dowels and bolts. Consequently, these modifications lead to revisions in the final drawing details. However, the current tunnel engineering practices lack systematic solutions that effectively bridge the gap between the iterative design process and efficient visualization of completed drawings due to the time- consuming nature of redrawing. This paper presents a pioneering application of AI-driven solutions including using Autodesk's API, for the Northside Interceptor Tunnel (NSIT) Project. It showcases the automation of drawing design and the real-time visualization of modifications, thereby streamlining the drawing process.

Jun 23, 2024

An open pit production planning method for stage mining is presented in this paper. The method brings solutions to the four most important parameters in stage mining : 1) the number of stages, 2) the size and geometry of each stage pit, 3) the mining sequence of the benches in the stage pits, and 4) the time of transition from one stage to the next. The method can also simultaneously optimize the ultimate pit, mine life, and production rate in each stage.

Jan 1, 1996

By Tamás Megyeri, Dániel Borbély, Vera Szánto, László Kovács

"Upon completion, the Bátaapáti deep underground radioactive waste repository complex (National Radioactive Waste Repository - NRWR) will provide safe final disposal for low and medium-level radioactive waste from the Paks Nuclear Power Plant in Hungary. The waste emplacement is in progress and one of the main concerns related to the development is ensuring a feasible plan is in place for permanent repository closure. Detailed hydrogeological observations and safety assessments revealed that the clay filled fault zones penetrated with the access tunnels play determinant role in the long-term confinement performance of NRWR, so they need to be plugged. Detailed mechanical analysis and numerical modelling of the tunnel constructed through a fault zone is presented here to gain a better understanding of the rock mass and rock support behavior. The effect of stress reflection is demonstrated and its consequences are described in detail. A recommendation is given for tunnel support design in such conditions. INTRODUCTION Crossing fault zones is a challenging task during tunnel construction and can lead to failure if not properly accounted for during design and construction. These failures are can be caused by high water inflow or stability loss of the rock mass surrounding of the tunnel (examples can be found in CEDD, 2015). The prediction of the magnitude and development of displacement has a considerable impact on issues during tunnel construction. Changes of rock mass stiffness or structure ahead of the face, to a great extent influencing stresses in the vicinity of the tunnel and thus deformations (Steindorfer, 1998). Further research with numerical simulations was carried out, and the qualitative and quantitative evaluation of displacement vector is presented in (Grossauer et al, 2005). The concern associated with crossing fault zones was considered during the design of the Bátaapáti deep underground radioactive waste repository complex (NRWR) in Hungary. In the case of NRWR project, the fault zones have an impact on maintaining the stability of the surrounding rock mass as well as the final sealing of the repository. As part of the final closure design, a complex numerical modelling program was completed to gain a better understanding of the mechanical behavior of the rock mass and the monitoring observations during construction. Even though the need for the presented study is closely related to the NRWR project, the results can be used in any project related to fault zone crossing. The methodology used to better understand the impact of crossing fault zones for the NRWR project is presented in this paper. First the project background is introduced including an overview of the underground facilities, the aim of the repository, and the construction experience gained from the first crossings of the fault zones. After that the in-situ and laboratory testing is summarized. The numerical modelling methodology is detailed in the next section. Not only the outcome of the model is presented, but the results are compared with the experience and observations made on site. Since a good agreement is found between the actual and the modelled behavior, the conclusions are based on the validated result. To fulfill the aim of the paper, the stress reflection concept is introduced to explain the mechanical behavior of the fault zone and the rock support; furthermore straightforward suggestions are made for rock support design."

Jan 1, 2016

By H. Burton

"The selection of the ultimate pit shell has a major impact on the overall value of a mining project. The size and shape of this pit drives the selection of pushbacks, equipment, and project strategy, each of which are significant in their own right. Optimization of the ultimate pit shape is typically done using the Lerchs-Grossman algorithm with inputs of production costs, commodity prices, and pit slope constraints. This method ensures that every tonne mined is profitable but does not take into consideration the timing of material release. This timing is essential when calculating the Net Present Value (NPV) of the project, which is one of the most popular metrics for valuing deposits. Often, when the mining schedule and discounting are applied, material that was considered profitable before discounting becomes sterilized. The objective of this paper is to show the methodology for improving ultimate pit selection by considering the production schedule. Application of this technique will generally produce a smaller and higher-value pit than using the Lerchs-Grossman algorithm alone. INTRODUCTION The Lerchs-Grossman Algorithm was developed in the 1960s and exists to produce a mathematically optimum shape for open pit mines (1). This algorithm is now an industry leading technique for producing the theoretical optimum shape for open pits and is used in many popular pit optimization and strategic planning software packages, such as GEOVIA’s Whittle. The Lerchs-Grossman (LG) Algorithm is based on graph theory and optimizes on the assumption of non-discounted cash flows. This produces a mathematically optimum shape, but does not consider the timing with which the material will be removed from the ground. This is an important consideration, given that one of the most popular metrics for evaluating mining projects is Net Present Value (NPV) (2), which relies on the timing of cash flows as a major differentiator between options. This paper will discuss issues inherent in the use of ultimate pit selection based on undiscounted economic factors and illustrate a simple technique in Whittle, a leading software package, which can be used to improve the NPV of projects."

Jan 1, 2015

By J. C. Harrison

Eldorado Gold Corporation of Vancouver, B.C. owns and operates three gold mines. The Sao Bento underground gold mine in Minas Gerais State, Brazil produced 105,907 ounces in 1997. The La Colorada and La Trinidad open pit, heap leach mines in Mexico produced over 83,000 ounces in 1997. With a deteriorating gold market plaguing the industry throughout 1997 Eldorado had to take critical measures at each mine to enhance gold production while lowering cash operating costs. Each mine had its own unique problems to confront. This case study will discuss three distinct courses of action taken at the three mine sites.

Jan 1, 1999

By Peter M. Fozzard

A review is made of the actual costs of recent foreign mineral exploration programmes in third world countries. Target identification leading to the selection of areas, or macro-targets, must follow a well planned and defined series of steps. Suggestions are made with respect to this inter-active project development work. Potential revenues in the broad sense will always determine the overall economics of exploration but clear objective philosophy, good planning and adequate financing are essential for exploration success. Considerable opportunities exist for making important foreign mineral discoveries and broad selected suggestions are made for the identification of exploration areas in relation to high-grade and precious metal mineralization.

Jan 1, 1984

By J. S. Hastings

Tertiary calc-alkalic to alkalic rocks of the Little Rocky Mountains in north-central Montana host low-grade heap-leachable gold-silver deposits being mined by Pegasus Gold Corporation. Total production from 1884 through 1985 is estimated at 22,625 kilograms (727,414 ounces) of gold. This includes 10,774 kilograms (346,400 ounces) recovered by Pegasus between 1980 to 1986 from 20,318,000 tonnes (22,396,000 tons) of ore grading 0.960 grams of gold per tonne (0.028 ounces per ton). Silver production during this latter period was 24,556 kilograms (789,500 ounces), but reliable silver statistics prior to 1980 are not available. Ore reserves as of January 1, 1986, were estimated to be 35,380,800 tonnes (39,000,000 tons) grading 0.720 grams per tonne (0.021 ounces per ton). Present ore production is 5,533,920 tonnes (6,100,000 tons) per year at a 0.45 to 1 waste to ore strip ratio. Current annual metal production is about 2,644 and 5,288 kilograms of gold and silver respectively (85,000 and 170,000 ounces of gold and silver respectively). The Little Rockies were formed by a calc-alkalic to alkalic magma penetrating through the Precambrian basement into the overlying Paleozoic and Mesozoic sedimentary rocks. This intrusive center is Dart of the Central Montana Alkalic Province, a region comprised of twelve separate intrusive centers aligned in a northeast trending belt measuring 200 by 400 kilometers (124 x 248 miles). The ore deposits are structurally controlled epithermal systems which vary from deeper narrow veins to shallow, wide, low-grade stockworks, breccias and intensely fractured "sheeted" zones. The shallow types are now being exploited. Primary mineralization consists principally of gold and silver associated with pyrite, native gold and silver, sylvanite, calaverite, and hessite. Alteration is broadly classified as weak argillic. Pyritization, kaolinization, silicification and feldspathization are the dominant forms of alteration. Fluorite is a common hydrothermal gangue mineral.

Jan 1, 1987

By T. P. Weldum, W. Conger

"The objective of the study conducted by the authors is to determine what media size(s) addition will maximize any given plant ball mill’s grinding efficiency (Fig. 1). The functional performance parameters “mill grinding rate through the size of interest,” and “cumulative mill grinding rates” from both plant and smallscale tests are applied to this task. A plant media sizing methodology, and industrial case studies, are provided.BackgroundA previous article (“Ball mill classification system optimization through functional performance modeling,” Nov. 17, McIvor et al., 2017, Mining Engineering) described circuit classification system efficiency (CSE), equal to the percentage of coarse (plus circuit P80 target size) material in the ball mill. It can be measured and then increased through pump and cyclone adjustments. By so transferring the application of ball mill power from fine (minus P80 product size) to coarse material, circuit efficiency is increased and overgrinding is decreased.The other factor that determines overall circuit efficiency is how well the power that is applied to the coarse material grinds it. This is affected by design and operating variables like the media sizing and mill percent solids. From circuit functional performance (McIvor et al., 1990):Circuit production rate of new fine material (t/h) = Power applied to coarse material (kW) x Mill grinding rate of coarse material (t/kWh) (1)The power applied to coarse material is the total mill power multiplied by the CSE. Therefore:Circuit production rate of new fine material (t/h) = Total mill power (kW) x CSE (%) x Mill grinding rate of coarse material (t/kWh) (2) Production rate, mill power and CSE can be measured during a plant circuit survey. The mill grinding rate of coarse material is then calculated. At the circuit target P80 size, this is the mill grinding rate (of coarse material) through the size of interest. The objective is to maximize this rate. The mill grinding efficiency can also be calculated by taking the ratio of the mill grinding rate over the material’s grindability as measured in the lab. Mill percent solids optimization has thusly been achieved (McIvor et al., 2000). For media sizing, maximizing the mill grinding rate on a given ore is equivalent to maximizing the mill grinding efficiency. Ores of different grindability will be part of the discussion."

Jan 11, 2018

By Douglas J. Kramm

This paper discusses the history and development of the Rotary Kiln in improved fuel economy. It discusses latest technology to optimize fuel economy in a long Rotary Kiln. It discusses the limestone preheater, the SF process for cement manufacture, and the flash calciner with suspension preheat and. suspension deheat for fine limestone.

Jan 1, 1977

By K. R. Miller

In recent years, surface mine equipment operators in the Campbell County region of the Wyoming Powder River Basin have found new ways to solve old problems. This paper will examine overburden stripping equipment and techniques by focusing on evolving applications for draglines, shovels, and dozers.

Jan 1, 1998

By K. Whiting

In October 1993, the first two of a series of full scale passive biological treatment cells were constructed to treat mine drainage from the Burleigh Mine (located approximately 48 km west of Denver, Colorado in the Clear Creek/Central City Superfund Site). The two cells are each 19-21 m long, 10.7 m wide and 1.2 m deep. Each cell contains approximately 216 cubic meters of substrate (composted manure) and is designed to treat 60 L/min of mine flow. One cell is designed as an upflow reactor and the other cell is designed as a downflow reactor. The differences in flow hydraulics and treatment efficiencies will be tested in these two cell for approximately nine months before the remaining cells are built to treat all the discharge. The substrate material was selected based on a series of bench scale tests. During the tests, the amount of metals removed was determined. The design flow rate was based on a sulfide generation rate of 400 nanomoles of sulfide generated per cubic centimeter of substrate per day. Metal removal results for the first three months of operation of the two cells will be presented and compared to results of bench and pilot studies at other sites.

Jan 1, 1994

By JA Vallejos

High stress underground mining poses a significant challenge to rock mechanics and rock engineering. To overcome theses challenges significative improvements in solutions and best practices of the design and operation of mines under high stress have been developed and implemented. This paper presents certain topics related to the management of high stress for sustainable underground mining. The topics include; the effect of preconditioning techniques (destress blasting and hydraulic fracturing) in the seismic rock mass response to underground mining and the dynamic behaviour of rock support systems. The opportunities associated with research in rock mechanics and practical rock engineering are discussed.

Apr 26, 2022