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By g. Caproni

The main constituent of the feed to the "Sulphide Section" (31 t/h), in the F. Sartori Plant (6000 tid) of the Miniere di Mon)eponi(Sardinia), is the ore of the Campo Pisano -Funtanaperda Mine (1 ? Difficulties have always been experienced in the treatment of this ore, owing to the extramely fine Pyrite-Sphalerite intergrowth and to the high Pyrite and soluble salts contents. The first mentioned difficulty was overcome with a rather complex flowsheet (see fig.1A and lB)(2); the others with a reagent combination that required a pH of 11 in a pulp loaded with soluble salts. This meant high consumption of alkalizer, and also of the other reagents; furthermore the alkalizer had to be mainly NaOH with only minor amounts of lime, because the latter tended to depress not only the pyrite but also the middlings, which were supposed to float. With dialchylditiophosphate alone as a collector, a lower pH could have been used, but a certain amount of amylxanthate was indispensable to promote flotation of the middlings. On the other hand, a bulk-flotation of sphalerite and pyrite at low pH could not be very advantageous on account of the high pyrite content in the feed(3).

Jan 1, 1971

By K. A. Lewandowski

Agglomeration techniques are widely used by industry to form fine particles into larger masses that are easier to handle and process. One area where agglomeration is potentially useful is in heap leaching operations. With-out agglomeration, fine particles travel through the heap, clogging the spaces between the larger particles and resulting in poor leach solution flow. Poor flow of leach solution will result in long leach rates and/or decreased metal recovery. Agglomeration immobilizes the fine particles and therefore improves heap permeability to fluid flow. Additional additives (binders) are needed to prevent agglomerates from breaking up as leaching solution percolates through the heap. Type II Portland cement and lime are two well-known binders used in gold and silver leaching, but these are limited to alkaline leaching environments. Various other products have been tested as binders, including polymers. This paper summarizes the benefits of agglomeration in heap leaching and the results obtained from the testing of several different agglomeration binders in heap leaching operations.

Jan 1, 2009

By M. Superfesky, P. Michael

Introduction The US Office of Surface Mining (OSM) is proposing changes to the Code of Federal Regulations in the interest of minimizing the adverse effects of excess-spoil-fill construction on the “prevailing hydrologic balance, fish, wildlife and other environmental values” (70 FR 35112). The proposed changes will require: (1) minimization the amount of excess spoil generated at a mine site; (2) minimization of the size of the fills constructed; (3) consideration of alternative configurations for disposal; and (4) development of a disposal plan that would minimize adverse impacts to the environment.1 To achieve those objectives, mining companies operating in steep-sloped Appalachia will likely build excess spoil fills (also called valley fills) that toe out at higher elevations in the hollows (i.e. to prevent or limit burial of streams). Consequently, the slopes of fill foundations will generally be steeper. Whereas the authors of this paper support these measures to protect the hydrologic balance and general environment, we wish to point out that placement of fills on steeper foundations can negatively impact the stability of the fills if proper care is not taken during their construction. It is important to note that in addition to impairing human safety, valley fill instability can negatively impact streams, the riparian habitat etc., and thus defeat the very purpose of the spoil minimization measures proposed. We do not, however, propose additional regulatory requirements pertaining to valley fill stability. Rather, we intend to emphasize the importance of engineering requirements already on the books, especially as they apply to the predominant type of valley fill constructed: the durable rock fill. We believe that the practice of restricting valley fills, to higher elevations in the watershed leaves less room for error in the design and construction of stable structures. This paper gives a quick review of the nature of excess spoil generation; methods and requirements of excess spoil fill construction, and the to-date stability record of the fills. The interest in excess spoil minimization and how it affects valley fill construction is also discussed. Most importantly, we will review long-standing issues pertaining to proper design and construction measures with respect to durable rock fills and discuss how they will become more critical as spoil minimization is practiced.

Jan 1, 2007

By Ashis Bhattacherjee, Rahul Upadhyay, Nearkasen Chau, Aditya Kumar Patra, Dhanjee Kumar Chaudhary

Heavy earth-moving machineries used in open-pit mines intensively expose the drill operators to whole-body vibration and shocks and thus to musculoskeletal disorders. The roles of an individual, machine, and rock-related factors in their exposure remain poorly understood. This cross-sectional study investigated their role among 39 drill operators from Indian iron ore mines. It shows that 70% of the operators were exposed to high levels of vibration, above the limit values recommended by ISO 2631-1. Multiple linear regression models showed that the whole-body vibration and shock exposures were strongly associated with operator’s age, drill machine model, rock’s hardness, uniaxial compressive strength, and density. The role of body mass index was close to significance (p = 0.08). Univariate analyses found that drill’s age, seat pad thickness, and seat backrest height were also strong predictors. These results help in identifying risky operators, materials and occupational situations, and in implementing appropriate prevention and intervention to reduce and monitor the exposures and health risk.

By J. Steenkamp, A. L. Hannaford, A. N. Jones

O’Okiep Copper Co. Ltd.’s 45-kt/month (49,600-stpm) concentrator at the Spektakel mine in South Africa is comprised largely of reconditioned equipment from the old O’Okiep mill, which operated from 1940-1975. When combined with modern approaches to layout, crushing, classification, and flotation, a simple-to-operate plant was constructed at a cost of only $3.2 million.

Jan 11, 1982

By Leon Maday, Dan L. Pecha, Jeremy Johnson, Daniel N. Adams

The Brightwater conveyance system includes 26 km of tunnels, a 130 mgd pump station, 2 km of micro tunnels, and a 2.4 km outfall. The tunnels extend from Woodinville to Puget Sound through varying soils in 1 to 7 bars of hydrostatic pressure and depths to 185 m. The tunnel diameters range from 4 to 6 m and include numerous lining systems. This paper highlights major shaft and tunnel design, including dual cellshafts, multiple pipe configuration tunnels, polymer concrete segments, and the use of a one pass lining designed to convey high pressure effluent.

Jan 1, 2005

By Karoly (Charles) Kocsis, Jeff Johnson, Felipe Calizaya, Tulio Dias, Natanna Nunes

Two pressure balancing chambers were constructed at a Colorado coal mine to reduce the risk of spontaneous combustion. Each chamber was established by installing a Kennedy stopping at about 10 ft (3 m) in front of an isolation seal, and equipped with two safety doors, a nitrogen injection system, and a set of environmental monitors. Several pressure balancing tests for different ventilation conditions were conducted in these chambers. During each test, pressurized nitrogen was injected into the chamber and the pressure differentials across the stoppings and seals monitored. This study presents a summary of the results achieved, lessons learned, and the basic requirements to operate a pressure chamber effectively.

Feb 1, 2024

By Simón Díaz-Quezada, HUMBERTO ESTAY

The heap leaching process has been widely used for recovering different metals since its first application at the end of the 1960s. In Chile, copper production via heap leaching has accounted for between 30 and 40% of annual copper production over the past 10 years. This level of production has been achieved through and supported by the use of a mathematical relation, known as the leaching ratio (LR) or irrigation ratio (IR), which relates operational parameters with metal extraction in a heap leaching operation. This ratio has been used to develop leaching column tests, to scale up results from the laboratory to industrial operations, to design new heap leaching plants, and in metallurgical control and production estimation. In spite of the widespread industrial use of this relation, few scientific studies mention it. This is due to its simplicity and basic theoretical foundations. This disparity between industrial practice and scientific research could lead to operational decisions which lack substantial theoretical support, and to scientific studies which have limited industrial impact. Against this background, several questions arise about the use of the LR: What are the constraints on the use of the LR? Are there practical advantages with respect to reported kinetic models? What is the main reason that industry prefers the use of the LR over kinetic models, which enjoy greater theoretical support? In order to guide its future use, this paper describes the leaching ratio and its current uses and limitations, through a literature review and case studies.

May 2, 2020

By James F. Reynolds

Introduction There are 1.4 Gt (1.5 billion st) of recoverable coal under less than 914 m (3,000 ft) of cover in Colorado in pitching seams. Snowmass Coal Co., in cooperation with the US Department of Energy, introduced the longwall mining method in pitching seams to North America. This venture is a coal mining research program directed toward the profitable production of coal under difficult mining conditions as found in pitching seams of the western US. Snowmass Coal classifies pitching seams into the following categories for longwall on the strike in seams 3 m (10 ft) or less thick: • Flat = 0 to 10°: Normal continuous mines and shuttle cars work efficiently. • Slight = 10° to 22°: The maximum pitch that rubber tired equipment will function. • Moderate = 22° to 40°: The angle of repose of mined coal. • Steep = 40° to 60°: The limit of safe use of this roof support. • Vertical = over 60°. The longwall roof support covered here will work in all pitches except vertical. The shearer and conveyor will work in flat through moderate conditions. Longwalling across strike with this equipment in seam pitch over 60° could be accomplished with an inclined face. Development of the first longwall panel began in 1979 and was completed in 1981. The longwall equipment was installed and mining began on Aug. 11, 1981. Mine Planning and Development The original mine plan took advantage of old works abandoned in the 1960s. The gates were developed on a two-entry system with the entries rising 2° to the strike, allowing water to drain from the face. The mining method was by Alpine F6A road header continuous miners with bridge conveyor type coal transport into 5.4-t (6-st) bottom dump coal cars hauled on 1.1-m (42-in.) gauge track by 7.2-t (8-st) battery locomotives. The initial concept was to haul coal from the longwall by battery locomotive. Lack of discipline, however, was shown in the irregular direction of the gate entries, and local rolls in the coal seams severely limited the capacity of battery locomotives. Current mining law prohibits using an intake escapeway for belts or trolley locomotives. A two-entry system is the simplest method of panel development in a pitching seam. A continuous miner cannot be trammed from one entry to another because of steep "X" cuts. Thus, the development requires a continuous miner in each entry. The configuration of the old mine works resulted in a first panel longwall block of three 108 m x 1.6 km (355 ft x 5,400 ft). In panel development, the use of battery locomotives for coal hauling became evermore costly. When the panels were completed and the setup room finished, the lower gate entry was changed to a belt entry and battery locomotives were abandoned. A new slope was driven and the mine supply system was converted to rubber tire diesel supply. The latest generation of roadheader and standard high powered shuttle car-to-belt system is now used for development. Selection of Longwall Equipment Longwall mining across the strike on pitching seams is currently practiced in many nations. Equipment similar to that used by flat seam longwalls is available for pitching seam use in Great Britian and Germany. Face equipment includes a twin outboard armored face conveyor. It was selected to give maximum retention of coal on the conveyor due to flight rigidity and to prevent coal from sliding down the face and jamming the lower belt gate. Also selected was a 22-mm (0.9-in.) Dowty twin-outboard face conveyor for a 106-m (350-ft) face with a single 112-kw (150-hp) drive

Jan 12, 1983

By Mark Rybak

On August, 31, 2006, Tropical Storm Ernesto hit the City of Richmond, Virginia. The Battery Park area was hit particularly hard, as flooding forced an evacuation of the area. A large sinkhole collapsed a sewer line in the Battery Park area, blocking the pipe and causing more serious flooding. This case history describes the fast track design, bidding, and construction of an emergency tunnel to bypass the collapsed sewer. Innovative value engineering, tunneling and shaft sinking methods, and final lining design all contributed to the success of this project. The storm inundated Richmond, Virginia with up to twelve inches of rain in some areas causing widespread flooding and damage. One of the hardest hit areas of Richmond was Battery Park. A major trunk sewer in the Battery Park area collapsed causing local combined sewer and storm-water flooding. The collapsed sewer was an 8'-3" wide by 9'-6" high arch sewer that was constructed in the nineteen twenties and later filled over with municipal solid waste and a soil fill cap to current elevations. A sinkhole was created in the area of collapse approximately sixty feet deep and one hundred feet in diameter causing the existing arch sewer to become blocked. As a result of this blockage contaminated flood waters reached depths in low lying areas in excess of twenty five feet. [ ]

Jan 1, 2008

By Gui DeReamer

Located on the Wabash River in the central portion of the state, the city of Lafayette, IN is relatively small compared to most cit-ies that incorporate tunnels into their combined sewer overflow (CSO) systems. The original CSO plan for the city was to replace two aging lift stations that were built in the 1950s. The original con-cept was to build a new sewer using conventional cut-and-cover construction to eliminate one of the lift stations ? the Parking Lot Lift Station ? and build a new regionalized one at the location of the Pearl River Lift Station. The initial sewer design was sized just to handle the flow that would eliminate the Parking Lot Lift Station. The planning for this project was being developed as part of the city?s CSO long-term control plan (LTCP) that focused on reducing the overflows from the city?s 14 overflow points. However, during the development of the CSO LTCP, a major industrial user indicated it would be increasing its flows to the system, which required additional conveyance capacity to meet the city?s CSO LTCP. After reviewing the design concepts with city representatives during the planning phase of the project, the mayor indicated that he wanted to minimize impacts to downtown businesses; therefore, trenchless alternatives were considered. The last piece of the puzzle that drove the project away from a small diameter pipeline was discovered during a flow monitoring program to collect flow data for the CSO LTCP project. This study revealed a major restriction in the 100-year-old Pearl River Trunk Sewer, located beneath four active railroad tracks. To eliminate this flow restriction, provide more overflow storage and reduce the impact to local businesses, a new 2.7- to 3.6-m- (9- to 12-ft-) diameter tunnel sewer became the most viable solution.

Jan 1, 2011

By Y. K. Yen, J. D. Miller, C. L. Lin

The image-based On-line Particle Size Analyzer (OPSA)system has been developed at the University of Utah to measure particle size distributions under plant conditions where overlapped and segregated particles are being transported on a moving belt conveyor. Evaluation of the OPSA system at several plant sites has been completed. The results show a consistent agreement between the particle size distributions obtained from the OPSA system and those obtained from laboratory screen analysis of belt samples. These results and the stable performance of the OPSA system during the field tests suggest that continuous quality control of crushed products is possible using the OPSA system.

Jan 1, 1999

By Harry R. Price, Bharat Doshi, Awni Qaqish, Abdul-Ghani Mekkaoui, Thaddeus Znoy, Ramesh Shukla

In 1992, a detailed inspection of the Southfield Sewer revealed a reach of approximately 0.8 kilometers in length, located directly below the freeway lanes, which was severely distressed. Failure of this section of the sewer would result in the closing of the busiest roadway in the state as well as the potential backup of sewage into homes and spilling into nearby surface waters. As such, repair of the distressed section required development of a procedure that would not jeopardize the conveyance of flow through the existing sewer nor impede travel on the overlying freeway. Based on these constraints, the DWSD and NTH team developed a repair concept that entailed the mining of a new, 3.05-meter (10-foot) diameter bypass away from the traffic lanes. The new bypass section was connected to the existing sewer, up stream and down stream of the distressed area, using a “top down” construction approach, that required only minimal freeway closures during weekend periods. This paper, prepared jointly by the Owner, Consultant and Contractor will describe existing conditions, design considerations and construction methods.

Jan 1, 2001

By K. V. Raj, VASU GANGRADE

Airflow in large-opening stone mines is largely dependent on the natural ventilation due to the large cross- section area of the opening. The openings of such stone mines are typically twice or thrice the size of typical underground coal or metal/nonmetal mines. Due to the influence of natural ventilation, air velocities as well as the static pressure drop in the mines are low. Mines rely on auxiliary fans to ventilate active faces to reduce contaminant exposure to mine workers. The National Institute for Occupational Safety and Health (NIOSH) is conducting research on ventilation of large-opening stone mines to reduce worker exposure to dust and other contaminants such as diesel particulate matter (DPM). In order to reduce worker exposure to dust and DPM, an understanding of the airflow pattern due to auxiliary fans in the mine is needed. Under this research, NIOSH researchers are exploring the computational fluid dynamics (CFD) modeling to understand the airflow behavior in large-opening mines. In this paper, the team is presenting the results from three-dimensional CFD modeling of airflow in a large-opening stone mine and investigating the effect of a fan placement with the movement of trucks.

Feb 1, 2025

By Bill Dershowitz

Consider a deep gold orebody with grade of 4 g/t (0.11 oz/st). At the time of this writing, with gold prices at historic highs, it could be a good, but not great, prospect. But if it is a vein deposit, and those veins are 200 g/t (5.8 oz/st), it would be significantly more attractive if there was a way to produce directly from those veins, leaving the rest of the rock in place. [Figure 1 The red around each of the four injector wells shows areas of high pressure, where the lixiviant fluid is pumped into the rock mass, with orange and yellow indicating dissipated pressure. The black lines indicate some of the fracture pathways through which the lixiviant, with absorbed metal, flows toward the central recovery well where low pressure is indicated in blue. Lixiviant is pumped out through the recovery well. Image courtesy of Golder Associates.] There is a way to do this, in situ leach (ISL) or solution mining. It has been a viable commercial technology for more than five decades.

Jan 1, 2011

By R. Heiser, J. Vendetti, B. P. Connor, E. J. Haas

"DISCLAIMER The findings and conclusions in this paper are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health. ABSTRACT Health and safety indicators help mine sites predict the likelihood of an event, advance initiatives to control risks, and track progress. Although useful to encourage organizations to work together, executing such risk assessments comes with challenges. This paper focuses on one trona mine’s experience in the development and implementation of a field level risk assessment program to help its entire organization understand and manage risk to an acceptable level. Through a transformational process of ongoing support and communication, Solvay Green River fostered a culture of trust and safety grounded in risk assessment, safety interactions, and hazard correction. The application of consistent risk assessment (RA) tools was critical to create a participatory workforce that not only talks about safety, but actively identifies energies that contribute to hazards and potential incidents. In this paper, reflecting on the mine’s process of RA implementation provides examples of likely barriers that sites may encounter when trying to document and manage risks. As discussed, consistent efforts to establish a participatory risk management program are worth the initial struggle to ultimately reduce incidents. INTRODUCTION Work-related health and safety (H&S) incidents often account for lost days on the job, contributing to organizational/financial and personal/social burdens [1-2]. Accompanying research demonstrates that risk and ambiguity around risk contribute to almost every decision that individuals make throughout the day [3-4]. In response, understanding individual attitudes toward risk has been unquestionably linked to predicting H&S behavior [5]. Although an obvious need exists to identify more comprehensive methods to assess and mitigate potential hazards, some argue that risk management is not given adequate attention in occupational H&S [6]. Additionally, research suggests that a current lack of knowledge, skills, and motivation are primary barriers to mitigating workplace risks [3-6]. Therefore, enhancing knowledge and awareness around risk-based decisions, including individuals’ abilities to understand, measure, and assign levels of risk to determine an appropriate response, is increasingly important in hazardous environments to predict and prevent incidents. This paper focuses on tailored approaches to field level risk assessment (FLRA), measurement, and common barriers to participating in such activities. The authors use a trona mine in Green River, Wyoming, as a case study to illustrate how the organization overcame widespread and site-specific challenges to implement a proactive risk management program. By discussing the mine’s tailored FLRA program, this case study contributes to the literature by first, providing examples of critical components that need to be in place to ensure successful risk management and second, context for continuous quality improvement that can foster a higher level of trust and empowerment on site."

Jan 1, 2017

By Robin Burgess-Limerick

The introduction of automation to mining has great potential to reduce safety and health risks by removing people from hazardous situations. However, automation changes the tasks performed by people and may introduce new tasks. For the system to function optimally, these tasks must be designed taking human abilities and limitations into account. Humansystems integration refers to systems engineering processes that ensure that human-related issues are adequately considered during system planning, design, development, and evaluation. During procurement of automated systems, a human-systems integration program plan should be prepared that describes the human-systems integration activities that will be performed to address each of the six core domains of human-systems integration: staffing, personnel, training, human factors engineering, safety, and health.

Jun 16, 2020

By James J. Brady

The basic story at Bear Swamp was how to excavate an underground chamber 79 feet wide by 227 feet long and 150 feet high, along with the related access, tarbrace, leads, power tunnels and shafts, do it under cost and ahead of schedule and still have just about everybody love you. The isometric sketch of the overall project follows. I won't go into any of the details of the physical scope at this point. Instead, we'll bring out the sizes, grades, particular problems of the different areas as we cover them. First of all, let's establish that Bear Swamp was a Target Estimate - Fee with Incentives type of contract. Gates and Fox's contract was with the project's general contractor, J. A. Jones. We were one of three contractors who submitted proposals and estimates to Jones. After much negotiation and many submittals, Gates and Fox was notified we had been selected to do the underground excavation on April 12, 1971. We had our first people back on site in two days, set up a temporary office, made our first steel order for jumbo erection, pacing our jumbo construction to meet the date when J. A. Jones would have the access portal ready for us. The shops, yards, dry house, compressor building were all erected as sites were designated for our use. At last, on Thursday, June 3, we trimmed the face and moved our 9-machine Euclid jumbo up a hastily constructed haul road and started our portal preparation of the access tunnel.

Jan 1, 1974

ITEC Environmental Colorado has begun reprocessing the tailings from old mining sites near Boulder, CO. And if the technology behind ITEC's pilot project at Gold Hill proves successful and profitable, the company plans to launch similar reprocessing operations in other parts of the state. The pilot project is under the watchful eye of state and federal authorities. They hope the technology becomes the answer to cleaning up old mining sites throughout the West. Remining and environmental cleanup on an economic basis, then, are ITEC's hopes in one the most environmentally conscious counties in the state. Clean up the mine dump sites and recycle the land, for a profit. In June 1998, ITEC Mineral Inc., ITEC Environmental Colorado's Canadian parent, acquired the Gold [ ] Hill Mill facility in Boulder County. Included in the acquisition was 4.4 hm2 (11 acres) containing the Gold Hill Mill and 283 hm2 (700 acres) of additional properties adjacent to the facility. ITEC estimates that there are about 910 kt (1 million st) of dump rock in the area. That is enough to make the operation viable. ITEC will sell the metals recovered through its reprocessing operations. However, due to low metals prices, ITEC is not expecting to make much money on the recovery of precious and base metals. Instead, the company plans to resell the reclaimed land for residential and commercial development or open space. The Gold Hill Mill site is the first of 17 sites in Colorado that ITEC Mineral hopes to clean up and recycle the land. Most notable among the sites is the historic Central City/Black Hawk mining district, which ITEC believes holds considerable potential. The Gold Hill Mill is located 14 km (9 miles) west of the city of Boulder and less than a half mile from the small town of Gold Hill. The mill was. last operated in 1992. The operation was forced to close that year due to environmental and cash flow problems. Gold Hill is in the middle of a region with more than 32 Mt (35 million st) of mine tailings. Independent geologists have' established the average grade of the Gold Hill mine tailings to be 4.5 to 5.3 g/t (0.13 to 0.155 oz/st) of gold and 28 to 44 g/t (0.83 to 1.29 oz/st) of silver. According to these studies, the Gold Hill mine tailings are five times richer in precious metals than the tailings of the Norebec Manitou property in Canada that ITEC is also remining, reclaiming and restoring. Upon acquiring the mill, ITEC undertook a refurbishing program that included adding a second ball mill. This increased the Gold Hill Mill's capacity to 180 t/d (200 stpd). The operation employs 15 people. "The Gold Hill Mill site will demonstrate the efficiency of our integrated remining, reclaiming and restoration process," said Maxine Stewart, president of Denver, CO -based ITEC Environmental. "The abundance of similar mine sites in Colorado presents a number of opportunities to bring the benefits of the ITEC system to other communities around the state." Holly Huyck is technical advisor to the Clear Creek Watershed Advisory Group. She said: "ITEC is cleaning up an orphan mine site that otherwise would continue to contaminate the Boulder Creek watershed with acid and excess metals. This is a win-win situation: ITEC gains marketable minerals while it reclaims mined land and helps to improve the watershed."

Jan 1, 1998

Bortech’s BoreClad corrosion protection system will be displayed at MINExpo. BoreClad is an innovative system for inside diameter cladding of nozzles, tubes and other circumferential devices. Pressure vessels, mud pumps and other mining equipment must be protected from corrosive caustic chemicals. Usually manufactured from mild steel, they can be clad with a protective material, such as stainless steel, to provide corrosion resistance. However, most welding processes leave voids where corrosion can damage the base metal. BoreClad provides void-free welds by combining gas metal arc welding with automated feed and rotation of chuckable parts. Workpieces of up to 915-mm- (36-in.-) long with a 460-mm- (18-in.-)swing can be clad with stainless steel, Iconel or other exotic metals. In addition to eliminating the voids associated with hand welds, BoreCladcan lay more than 2.2 kg/h (5 lbs/hour) of metal. That is a significant reduction in weld time. Web sitewww.bortech.com.

Jan 1, 2004