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By J. Duran

Mining at Phoenix is currently done by surface operation in the Fortitude and Bonanza Pits, at a combined rate of approximately 110,000 tons per day. A portion of the ore bodies targeted by these pits was mined previously by underground mining methods, dating back to the mid to late 1800?s. Most of the underground workings (voids) are located in the west central area of the Bonanza Pit. The surface operation requires excavation through voids, and there is a risk of pit floor subsidence that has to be addressed. This paper presents a review of the risk mitigation measures that were implemented to reduce risks to people and equipment working in the area.

Feb 23, 2014

By Ebelia Manda, Peter RK Chileshe, Sydney Chinyanta, Abdul Samson, Victor Mwango Bowa

Buttressing is a widely employed control measure for mitigating slope failure in various settings such as openpit mines, road sections, dams, and hilly or rocky terrains. This paper presents a study on the effects of buttressing, specifically concerning slide-head toppling failure. Drawing insights from a case study of slide-head toppling in Zambia, our investigation employs both analytical (limit equilibrium) and numerical (3DEC software) modeling techniques. The analytical and numerical models exhibit notable similarities in their schematics and overall results, revealing a subtle effect of buttressing in controlling slide-head toppling failure. This study contributes valuable insights into the nuanced role of buttressing in slope stability, with implications for optimizing buttress design parameters. While the overall findings suggest a modest influence of buttressing on slide-head toppling failure, further discussions delve into the specific implications and potential refinements for practical applications.

Jan 1, 2025

By Stanley A. Bunk, Desmond J. Bruyns

The purpose of roasting gold ores is to release for extraction, typically by cyanidation, the small particles of gold which are surrounded by refractory stone. The roasting simply opens up passages for the penetration of solution into the interior of the ore particles. This is accomplished by the removal by volatilization or formation of volatile oxides of certain constituents such as sulfur, arsenic or antimony. Temperature is an important parameter. High temperatures tend to form a dense iron particle rather than a "spongy" calcine. The dense iron particles result in lower gold recoveries. High temperature can cause melting of some components which also results in gold encapsulation. Roasting of refractory gold ore concentrates has been practiced for decades. Multiple hearth, rotary kiln and muffle reactors were first used for roasting. Fluid bed roasting provided a low capital cost, low maintenance technology with better process control and soon became the favored technology. The first fluid bed concentrate roasters were commissioned in the late 1940's. Early fluid beds were "bubbling" type. Environmental considerations did not significantly impact on the design. Feedstocks were highly exothermic and reaction rates were relatively rapid. Roasting today must compete with other technologies for treatment of refractory ores. Ore bodies which are not

Jan 1, 1993

By Ernesto Maldonado, Jesus Romero Benitez, Zach Agioutantis

Numerous researchers worldwide have investigated the prediction of ground movements due to underground coal mining utilizing different analytical, empirical, and numerical models. These studies have primarily focused on the development of prediction methodologies for either flat or gently dipping seams under variable topography, and only a few studies are available that have investigated the prediction of ground movements over inclined seams. Although most inclined coal seams are in China, India, and other countries worldwide, a few inclined coal seams (with a dip of 10 degrees or greater) are also present in the US. Currently, the prediction of ground movements for inclined coal seams using empirical methods utilizes the same methodology for horizontal seams. It consists of dividing the inclined seam into horizontal segments, calculating deformations due to each segment, and superimposing the calculation results. This paper presents a new tool that provides a methodology for modeling subsidence under inclined seam conditions. Examples based on subsidence measurements available in the literature are presented. The goal is to implement this methodology into the Surface Deformation Prediction System (SDPS).

Jun 25, 2024

By T. S. McGahey

The southeastern region of the United States has long been a major market area for coarse and medium particle size natural ground calcium carbonate fillers. The primary market for calcium carbonate in the southeast traditionally has been as fillers in building materials such as carpeting, joint cement and roof shingles. In these applications the economic value of the calcium carbonate in the final product is weighted more toward lessening the cost of the final product, as opposed to contributing any desirable physical characteristics. For example, in carpet backing applications the calcium carbonate filler does little more from a physical standpoint than add weight and body to the backing adhesive. The important factor in the use of calcium carbonate in carpet backing is that it can be used at high loading levels to replace the more expensive latex binder, thus lessening the cost of the final product. It is estimated that calcium carbonate producers in the southeast sell in excess of 200,000 tons (181,436,000 kg) annually for use in latex compounds for carpet backing applications.

Jan 1, 1986

By J. Raatikainen, I. Auranen

"INTRODUCTION Sorting technology has advanced rapidly recently. Of the two possibilities particle sorting has advanced especially in introducing new sensors and the use of multiple sensors. The analyzing and computing lead times have also shortened. This has made it a viable technology option for many applications but not for the most important sorting task at a mine; the run-of mine ore. Bulk sorting, however, has advanced in smaller steps, even if the technology has the capability to tackle the run-of-mine ore and offers a high potential to bring mines substantial economic benefits. The sensors, which are useful are restricted by the difficult operating conditions or by the ore characteristics. One of the important features of run-of-mine sorting technology is the major material handling infrastructure required. The capital expenditure can be substantial requiring good understanding of the sortability curve (grade-recovery curve) behavior of the ore. This paper discusses one industrial case, where substantial amount of data measured from the ore feed belt has been obtained. This data was then analyzed for the grade recovery curves obtainable from that ore with sorting. EXPERIMENTAL The XRF measurement used was the FCA device from IMA Engineering (Fig.1). It is a specially built version of XRF designed to operate with coarse material. The measurement was situated at the main belt conveyor taking ore from the primary crusher to the stockpile. The crushed ore was about 80% -300 mm at a capacity of 1100-1200 tph (Fig.2). Measurement times were varied from 30 seconds to a minute. Measurements were obtained over several months.As the XRF is a surface distribution measuring technique, the measurement was first tested upon accuracy and reproducibility against plant daily wet chemical assays and against on-line Courier feed analysis. As there is a varying delay in the ore stockpile, the delay time was used as a variant in the validation. Different measurement times were tested for accuracy. A one minute measurement time gave a total measurement relative standard error, which was both for Cu and Ni below 3%. The results showed also very robust correlations; for Cu, the correlation coefficient was R > 0,94 for one minute measurements over three months and R > 0,86 for Ni respectively. Fig 3. Shows a measurement period of two hours showing substantial feed grade variations (given as relative value; 1.0 represents the mean value during the measurement month)."

Jan 1, 2018

By E. Stone, R. Reagan

Risk of hand injury is very real for operators carrying out conventional bolting operations with power torque tools, reaction arms and backup wrenches. Bolting operations of this type are common today in the installation and maintenance of heavy mining machinery and equipment. Newer solutions have become available that have the potential to dramatically reduce the risk of hand injuries in mining applications. MINING APPLICATIONS Within the scope of mining operations, various types of equipment are used such as tunnel boring machines, bucket wheel excavators, draglines, material handlers, screens, pumps, crushers, continuous miners and longwall systems. Design of these machines typically includes larger diameter bolts for strength and durability. Due to rugged use all machines require frequent maintenance and service which requires the use of heavy industrial bolting tools and methods. Those engaged in bolting operations include technicians working for end-users, equipment manufacturers, general contractors and others who provide services in mining operations. Most all personnel involved with these activities are engaged with use of high power bolting tools and procedures. Training is essential to raise the awareness of bolting safety and to avoid accidents. However improved bolting tools and procedures can play an even more significant role in further improving the safety of all those engaged with bolting in the mining industry. SAFETY CONCERNS Professionals working in the mining industry are constantly looking for ways to further reduce risk to health and safety. Bolting operations which are fundamental to service and maintenance of mining equipment are often overlooked as a potential area for improvement. Several areas of bolting operations offer potential for improvement in safety and avoiding accidents during equipment maintenance. This paper addresses the safety concerns associated with reaction arms and backup wrenches in conventional bolting applications (Figure 1).

Jan 1, 2019

By Brian Hays, Victor Mwaba

Optimization of water use has become a top priority for virtually every mining operation. The mineral extraction process typically requires vast quantities of water, which can be particularly challenging when a mine is located in an arid location. Most mining permits have very strict limits on water usage, so tight control of water utilization and extensive recycling are critical to regulatory compliance and profitability. Water management is not only dependent for selecting the right flowmeter for different applications.

Apr 1, 2026

By G. J. Goldberg

Through the early 1980's, surveying at Bingham Canyon required a great deal of repetitive and manual work. The advent of total station surveying equipment provided an opportunity to improve the speed and accuracy of surveying work while reducing manpower needs. An evaluation of total station systems and their ability to meet the surveying requirements of Bingham Canyon culminated in the purchase of a total station system as the mine re-opened in 1986. This paper presents the procedure for evaluating, implementing and using the total station survey system at Bingham Canyon.

Jan 1, 1990

By A. P. Schissler

2013 has seen metals, industrial minerals, and coal all reduce in price due to market and geo-political factors. Many companies are taking write-downs to recalibrate their reserves and have enacted focused cost reduction programs. The public domain includes statements where companies have operating cost reduction goals in the $500 million range. Zero-base staffing & budget analysis is a means to achieve optimal employment and cost levels for a given level of production. The method involves measuring the work to be done similar to Lean. Lean is a method to review each step of production and remove anything that doesn?t add value or is necessary to complete finished goods. Zero-base methodology has been applied to mines worldwide producing realistic and sustainable levels of staffing and costs based on the quantity of work. The objective of this paper is to provide the framework of zero-basing with examples of application.

Feb 23, 2014

By M. S. Davis

The Tek Process can produce masonry products such as bricks, roof or wall tiles, and block from virtually any inorganic waste. In the process the aggregate raw materials, portland cement, water and common chemicals are first mixed together; then mechanically subjected to several thousand pound pressure per square inch. This causes a novel chemical reaction between the cement, chemicals and water; producing the "patented" Tek adhesive binder which holds the aggregate together in a stone-like mix. Simultaneously, the desired product shape is formed. The building modules can have strengths of 8000 p.s.i. (pounds per square inch) with completely sound aggregates utilizing air curing for a period of 28 days. With most aggregates, 3000 p.s.i. is achieved within 24 hours. Eventual strengths usually exceed 5000 p.s.i. with almost any raw material. Water absorption ranges from 5-7.5 percent. Both absorption and strength figures are superior to the most rigid of any and all A.S.T.M. specifications for the highest quality bricks. In most locations, the product (when brick shaped is called Tekbrik) can be produced significantly more economically than can comparable grades of clay or other bricks, be- cause almost any inorganic waste materials or pollutant can be used as a raw material. The process results in a lower manufacturing cost as compared to clay bricks; fuel cost to operate a clay kiln represents a substantial portion of the total cost. Capital expenditure for a Tek plant also is lower due to the large investment in clay kilns. Transportation savings also are important, clay brick factories must be very large because the kilns are uneconomical unless they are large. Most bricks are manufactured at the sites of clay deposits in relatively uninhabited areas. The cost of transportation to the job site represents a considerable percentage of the selling price.

Jan 1, 1974

From a gathering storm of climate change based legislation that could potentially overwhelm the mining industry, to the nuts and bolts of mineral processing and just about everything in between, about 100 mining and mineral processing professionals heard it at all at the 60th annual Colorado MPD Meeting April 22-24 at the Broadmoor in Colorado Springs, CO. With a sweeping agenda under the banner ?What in the world is new in mining and metallurgy? attendees were treated to four sessions and 21 presentations that covered the range of mining industry issues. Bill Reid, president, chief executive officer and director of Gold Resources Corp., spoke about his company?s El Aquila gold project in Mexico. With five projects in Mexico, Gold Resources Corps. is aiming to become a low-cost gold and silver producer. Its flagship property, the El Aguila gold project, is a high-grade gold and silver property with significant base metal credits of copper, lead and zinc. Production of the El Aguila project was targeted for mid-2009. Reid said that three high-grade deposits have been discovered at the El Aguila project. They include the high-grade ?manto? style El Aguila openpit deposit, the El Aire high-grade polyme-tallic vein system, which is underground, and the underground La Arista high-grade polymetallic vein system. The project is located 120 km (75 miles) south-east of the capital city of Oaxaca, Mexico. Reid said the property has yielded several exceptional gold and silver surface samples, including a 36-g/t (1.1 oz/st) gold sample and a 3,100-g/t (90 oz/st) silver sample. Other properties that Gold Resource Corp. has are:

Jul 1, 2010

By M. Gorman

The Mineral Park Mine is an open pit copper-molybdenum mine located in northwestern Arizona, approximately 74 miles southeast of Las Vegas, Nevada. The property has been owned by the Duval Corporation, Cyprus Mining Company and Equatorial Mining of Australia. Mercator purchased Mineral Park from Equatorial in 2003. Mineral Park commissioned a 25,000 tpd copper and molybdenum concentrator in November and December of 2008. The process includes two stage milling (SAG and Two Ball Mills) fed by primary crushed ore. Metals are recovered in a copper-molybdenum flotation circuit consisting of mechanically agitated roughers and cleaners. The copper- molybdenum flotation concentrate is thickened and further processed in the molybdenum flotation circuit which separates the copper and molybdenum minerals into salable concentrates. The molybdenum circuit also uses mechanically agitated cells. This paper describes the plant and some of the highlights of the commissioning process.

Jan 1, 2010

By Nasri Munfah, Raymond E. Sandiford

"Superstorm Sandy (Sandy) created a storm surge that inundating many of the tunnels that pass beneath the Hudson and East Rivers. The tunnels are vital infrastructure links for the economy of New York City and the northeast region. The sea water, which contains highly reactive salts, caused significant damage to electrical and mechanical systems. In addition, the salt water inundation left corrosive precipitants on the tunnel linings and on and within electrical duck banks. After the salt water was evacuated from the tunnels, condition assessments were performed using a state of the art approach involving high resolution laser scanning, digital imaging, and thermal imaging. These scans were performed prior to hands on inspections. The damage assessment concluded that, although the tunnel structural linings were not damaged, the interior elements of the tunnels needed major rehabilitation to arrest the continual deterioration of the structures. This paper details the state of the art approach used for these tunnel inspections. INTRODUCTION On October 29, 2012 Super Storm Sandy flooded a large number of both transit and vehicular tunnels in the New York Metropolitan area. The region’s transportation network was severely disrupted. The storm damage is estimated to have been in excess of $30 billion, and with the tunnels out of service, the local economy was losing hundreds of millions in economic activity. Restoration of these tunnels was a very high priority and the resulting expedited restoration process did not always provide adequate time for comprehensive condition surveys. This resulted in many of these surveys being conducted after service restoration. Inspecting highly trafficked transit tunnels is challenging and the logistics of working in short night outages led to a rethinking of the conventional inspection approach. Traditionally, visual and tactile methods are first used to inspect tunnels and then quite often followed by LiDAR (Light Detection and Ranging) scanning and perhaps infra-red scanning. For multi-mile tunnels, the time required to visually map tunnel features can be quite extensive. By performing the scanning first and then performing the visual and tactile inspections, one is able to use the scan data to identify the specific areas that need detailed inspections. This approach was used quite successfully for a number of the NYC tunnels."

Jan 1, 2016

By R. D. Hagni

Pyrometallurgical products from lime roasting of refractory gold ores, pyrite, and arsenopyrite have been examined for their mineralogy, porosity, permeability, retention of contaminant sulfur and arsenic, and potential effectiveness of gold extraction. Cathodoluminescence microscopy, supplemented by X-ray diffraction and scanning electron microscopy-energy dispersive analysis study, has shown that the products phases have characteristic cathodoluminescence properties as follows: anhydrite (CaS04), deep blue; unreacted portlandite (Ca(OH)2), deep purple; oldhamite (CaS), light yellow to rarely pink or orange; a sulfur-rich, arsenic-poor phase, violet; an arsenic-rich, sulfur-poor phase, non-CL. Within the temperature range examined (400-850°C), hematite exhibits greater porosity and permeability at the intermediate roast temperatures of 600-650°C.

Jan 1, 1993

By Howard W. Earnest

The Rio Blanco Oil Shale Company completed a modified in situ oil shale retorting demonstration at its Tract C-a Lease in the Piceance Creek Basin of northwestern Colorado during the spring of 1982. This demonstration was the first MIS project with shafts rather than adits for access to the mining operation, and it involved several potential hazards which required that particular attention be paid to mine ventilation. Methane was first encountered during shaft sinking and ultimately resulted in the mine being classified gassy by MSHA. Secondly, we encountered hydrogen sulfide in association with the ground water, and this proved to be a more persistent problem than did the methane. Thirdly, in order to burn the underground retorts, it was necessary to provide for potential leakage of retort gases and to obtain a modification to the MSHA standard which forbids fires under- ground. This modification had a significant effect on the ultimate ventilation procedures at Tract C-a. An extensive under- ground air monitoring program was included in the ventilation system.

Jan 1, 1983

By Bradley V. Nelson

A number of improvements in the ventilation system at the Henderson Mine have been made during the past several years. A key to these improvements was the installation of a computerized monitoring and control system. Employees can determine the status of any of hundreds of devices in seconds through the use of this monitoring system. Mine dewatering pumps, the water treatment system, the ore haulage system, electric power usage as well as other devices are controlled and/or monitored. Ventilation parameters which are monitored include air flow volumes and carbon monoxide as well as the status of main surface fans, mine doors, and ventilation raise doors. Main underground fans are also constantly monitored and can be controlled remotely. These underground fans can be programmed to automatically start and stop to follow work schedules, optimizing air quality while reducing power cost. Mine air heating costs have been reduced by replacing an electrical resistance heating system with a direct fired natural gas heating system at the portal of the ore haulage tunnel.

Jan 1, 1995

By T. Deschaines

Raman Spectroscopy has become increasingly popular as a method to rapidly identify and characterize minerals, gem stones and other inorganic materials. Raman spectroscopy provides valuable information about the chemical bonds and structure of materials. In fact, the peak locations and intensities observed in a Raman spectrum can often be used to confirm the presence or absence of particular species in a sample. Some modern Raman spectrometers have been designed to analyze samples less than a micron in size while others are designed to rapidly screen bulk material with no sample preparation. Recent advances in software and automated instrument control have greatly reduced the complexity of Raman spectral analysis and provide an easy-to-use tool for analyzing minerals. We will describe the application of several multivariate statistical analysis techniques that have been developed to make use of the spectral libraries. In these techniques the spectrum is treated as a vector and sophisticated mathematical techniques are used to determine which spectral representations in the reference library best match the spectrum from the sample. The DXR Raman microscope was used to 1) Identify minerals by spectral searching, 2) Identifying several species in a sample using multi-component analysis 3) Mapping different species in an aggregate sample and 4) identifying inclusions in a sample.

Jan 1, 2010

By D. Kelley

Due to pricing volatility and lack of availability of metals, the use of non-metallic materials of construction in metal extraction and refining processes has increased significantly in recent years Even though costs and availability of metals has improved recently, these factors are not expected to continue into the future as metal supplies once again fall short of global demand. One of the most common non-metallic materials of construction used in metal extraction and refining processes today is Fiberglass- Reinforced Plastic (FRP). These processes often require materials of construction that can resist acids and high concentrations of acid chloride salts. As shown in Table 1, FRP based on epoxy vinyl ester resin has the same chemical resistance to acid and better resistance to acid chloride salts than alloy C-276 and is superior to 2205 stainless steel in both cases.

Jan 1, 2010

By J. Pereyra, M. DeMarco

"INTRODUCTION It can be vital that bolted joints holding subassemblies together remain secure. Bolts should resist the loosening effects of vibrations and dynamic loads yet need to be easily removable during maintenance. When a threaded fastener is subjected to vibration, the rapid movement causes a lowering of friction against the threads and a subsequent loss of preload. The loss of preload allows the fastener to vibrate loose and possibly fall out. As the diameter of fasteners increase desired preload becomes increasingly more difficult to achieve. Input torque requirements for achieving proper bolt preload is exponentially related to any given fasteners diameter. This means that specialized tooling or bolting practices are usually required to attempt the tightening of fasteners to reach their required preload. Traditional methods can cause problems with joint integrity and do not provide consistent bolt load across the bolted surface. BOLTED CONNECTIONS A failed critical bolted joint can lead to high maintenance costs, machine downtime, and risk to worker safety. Control of the clamp load in a bolted joint is vital. However, when faced with a problem joint, it is not surprising that the design engineer will not have an answer if asked about the clamp load. Torque calculations must always be based on the existing conditions that often are vague. Unless all parameters are correct, the calculation will be unreliable. Examples of parameters are: • Thread condition of the fasteners • Hardness of contact surface • Material (steel, aluminium, copper, etc.) • Extra friction from a locking fastener • Extra friction from an adhesive • Lubricant on the thread • Type of bolt head (flanged, regular or serrated) • Surface coating of the bolt • New or reused fastener During tightening, bolts are subjected to both tensile and torsional stress. The total stress in a bolt can be calculated using the formula: Total stress = vsx2 + 3txy2 In order to maximize the desired tensile stress (sx) it is vital to minimize the torsional stress (txy). Tensile stress (clamp load) is achieved when the bolt is axially elongated. Unwanted torsional stress (twisting) in bolts arises during tightening due to thread friction. High thread friction increases torsional stress and causes yielding at lower clamp load levels than normal. A lubricant is necessary to minimize the malign torsional stress. However, many commonly used bolt-locking systems are based on increased thread friction (deformed nuts, adhesives, etc). To minimize thread friction and concurrently safely secure the joint has often incorrectly been considered impossible. The use of locking systems that increase thread friction is the single most common reason why the full capacity of bolted joints is not utilized. The following example illustrates the problem."

Jan 1, 2015