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By Louis M. Perlman

Quantitative methods are, by now, a standard tool of the mining industry, and are commonly used by Research Departments in their evaluation of production methods and schedules, and their associated costs. Indeed, much sophisticated computer work has been devoted to such evaluation of controllable costs and capital requirements. These data are an important input into the project evaluation formula, which is probably the most important single calculation per formed by a mining company, since the result decides whether a particular project is viable. It is instructive to summarize the broad principles of project evaluation, since they are crucial to the remaining sections of this paper. PROJECT EVALUATION The most widely used method of appraising projects is known as Discounted Cash Flow (DCF) method. Two main variants are used; they are known as the 'not present value' (NPV) approach and the 'internal rate of return' (IRR) approach respectively. The difference between the two is that the former takes the firm's interest rate as given and uses this knowledge to calculate the present value of the project; whereas the latter calculates the highest interest rate the project could tolerate and still just breaks even. The technique is more simply discussed in terms of the first method (NPV).

Jan 1, 1972

By C. Vass, A. Noble

"The chemical treatment of mine-influenced waters is a longstanding environmental challenge for many coal operators, particularly in Central Appalachia. Mining conditions in this region present several unique obstacles to meeting NPDES effluent limits. Outlets are often located in remote areas with challenging terrain where conditions do not facilitate the implementation of large-scale commercial treatment systems. Furthermore, maintenance of these systems is often laborious, expensive, and time consuming. Many large mining complexes discharge water from numerous outlets, while using environmental technicians to assess the water quality and treatment regime multiple times per day. As an alternative solution, this paper describes the ongoing research and development of automated chemical treatment systems for mine water discharges. The current work explains the development of a bench-scale prototype that has been used to evaluate various monitoring, notification, and control strategies. Results from this testing are compared to present day practices to show the costs and benefits of implementing an automated treatment and monitoring program. INTRODUCTION Background The National Pollution Discharge Elimination System (NPDES), per Section 402 of the Clean Water Act, requires permitting of all point source discharges from coal mines. This program dictates that all water leaving a permitted boundary, whether it be process water or storm water, must leave through a monitored NPDES outlet. These permitted NPDES discharge points, also denoted outlets, outfalls or monitoring points, must meet a rigorous set of effluent limits to maintain compliance. Common effluent limits monitored by coal companies include but are not limited to iron, manganese, aluminum, total suspended solids (TSS), and pH. Raw mine water is often deficient in meeting these effluent limits, and as a result, various treatment processes are required to bring the water into compliance prior to environmental release. Depending on the mining and geologic conditions, water monitoring and treatment programs can constitute a significant operating cost for the mine operator. In Appalachia, acid mine drainage (AMD) constitutes one of the most significant and widespread water quality challenges that must be treated per NPDES guidelines. AMD is a general lowering of water pH that occurs when water and sulfide minerals interact within oxidizing conditions in coal and metal mining. Acid Rock Drainage (ARD) is a similar term that applies more generally to non-mining causes such as highway construction and other large-scale excavations. Today, mine influenced waters (MIW) is becoming more popular as the general term referring to all types of mining-induced water issues. AMD has been researched substantially over the last 30 years, with investigators studying various causal mechanisms and treatment strategies (e.g. Gazea, 1996; Ziemkiewicz, 1998; Skousen, 2000; Kleinmann, 2001; Johnson, 2003; Akcil, 2006; Kalin, 2006). This research has produced several pragmatic results, which provide numerous methods to predict, prevent, and treat AMD."

Jan 1, 2016

By Manchao He, Xiaoding Xu, Yubing Gao

Based on the geological conditions of the 15,600 working face in Pingba Mine, this paper establishes the mechanical model of the stress distribution in the pre-working face under the influence of mining pressure based on a hemispherical stress distribution theory. The analytical formula for the stress distribution is determined. A numerical model for the mining pressure under the influence of key layer is also constructed, and dynamic stress interruptions under various roof-cutting relief schemes in different horizontal positions are simulated. The stress distribution of the stope under different pressure relief schemes is analyzed and compared with the theoretical results. Results show that blasting roof cutting blocks the transmission of the abutment pressure to the working surface to the coal and rock mass in front of the working face, reducing the significant working face mining pressure influence range, which decreases as blasting pressure relief position moves toward the working face. Stress accumulation in the coal in front of the working face also increases as the blasting pressure relief position moves toward the working surface. Engineering practice results show that blasting cutting can effectively block the propagation of mining pressure, and the stress impact range is shortened by approximately 1/3.

Jul 31, 2021

By M. Deutsch

A common casualty of modern open pit mine optimization is the assurance that the resulting design is actually achievable. Optimized mine plans that consider value and a bare minimum of precedence constraints do not, in general, translate into practical, operational mine designs that can really be used in the field. Ultimate pits may come to a sharp point at the bottom. Schedules may require taking small parcels of material from many disparate areas of the pit in a single period. And grade control polygons may be ragged, narrow, and not minable with realistic equipment. In this paper all of these problems are addressed by encoding these three fundamental open pit mine optimization problems as maximum satisfiability problems. Maximum satisfiability provides a useful framework for problems that are non-linear and may guarantee the optimality that metaheuristics cannot. INTRODUCTION Open pit mines are large and complicated operations, which require significant initial and ongoing investment. A single mine may employ hundreds or thousands of people and creates substantial benefits for both the surrounding and global communities. Planning an operation of this magnitude requires a lot of effort and cannot be done optimally by hand. Mining engineers today rely on many techniques from operations research to guide decision making, and to maximize the value of the mine. Techniques including linear programming, metaheuristics, and network algorithms are all used to solve different problems throughout mine design and optimization. However, techniques based on Boolean satisfiability, including the optimization extension of maximum satisfiability, have not seen much use in mining despite being used in many other fields including electronics design, scheduling, and artificial intelligence. We claim that maximum satisfiability is a useful and meaningful way of expressing and solving optimization problems in mine planning. However, this technique does not come without challenges; the problem is NP-hard, and modern techniques for solving these problems can struggle with the number of variables and clauses that a typical mining problem requires. Also, some of the constraints that mining must contend with do not fit nicely into the satisfiability paradigm. Despite these challenges, we believe that maximum satisfiability provides a useful framework for considering operational constraints and expressing some problems that other techniques can't easily express. Maximum satisfiability can be solved exactly, yielding the true optimal answer which metaheuristics cannot guarantee. In this paper we show the applicability of maximum satisfiability to mining by specifying three fundamental problems in open pit mine optimization. We show how these fundamental problems can be formulated and how they can be extended within the framework of maximum satisfiability. For the remainder of the paper we first give a brief background on common elements between the three problems and an introduction to satisfiability. Then we tackle the three problems; the Ultimate Pit Problem, the Block Scheduling Problem, and the Grade Control Polygon Problem. In the Ultimate Pit Problem we specifically show how to extend the problem to support a minimum mining width – a coveted result for many mining engineers. We then discuss some of the complexities and shortcomings of this framework and possible research directions.

Jan 1, 2019

By J. L. Kohler

Control circuit failures contribute significantly to continuous miner downtime. The time required to put the machine back into production is a function of the time required to diagnose the problem, obtain parts, and make the repair; of these, the diagnostic time is often the largest. A microprocessor-based system with the ability to diagnose all of the common control circuit failures was designed, installed on a continuous miner, and tested. This paper summarizes the development of the diagnostic system, and provides examples of the system's diagnostic capabilities. Implementation issues and the hardware used for the prototype are briefly described. Finally, comments on the system's performance are presented.

Jan 1, 1993

By A. Durnan

Barrick Goldstrike Mines Inc. (Goldstrike) operates a six circuit (train) pressure oxidation plant for the pretreatment of gold bearing sulfide ores. The property is located 27 miles north of Carlin, Nevada. Since the commissioning and start-up of the first circuit in 1990 until the present total plant availabilities have exceeded 90%. The discussion that follows will detail the maintenance practices employed to consistently achieve this goal.

Jan 1, 1994

By X. Song, Q. Zhang

"The development of fracture zones in surrounding rock mass has significant impact on the stability of underground mine roadways. Detection of the fracture zones is of compelling importance for maintaining roadway stability as well as for safe and speedy excavation of the roadways. This paper presents a study conducted at Dong Bao Wei underground coal mine, where the roadways were developed in diabase rock mass. The roadways suffered severe damages, including sloughing and excessive floor heaving. The borehole imaging technique was applied in the study to observe and detect fracture zone development surrounding the roadway openings. Based on the borehole imaging studies, new roadway support systems were proposed to improve the stability. INTRODUCTION At the Dong Bao Wei Coal Mine three main roadways of the west wing were excavated. The three roadways had semicircle arch cross sections and were at a depth of 650 meters, each being about 750 meters in length. The roadways were driven through a section of thick diabase intrusion, which was softened by water with reduced strength and may turn into powder form under weathering. Site investigation indicated that the roadways in diabase intrusion zone were badly damaged due to severe deformation, and very serious roadway sidewall sloughing and spalling accompanied by severe floor heave often occurred.(Figures 1 and 2) In order to ensure the normal use of the roadway, undercuts were excavated. However, this operation seriously affected the roadway construction progress and increased the amount of roadway support operations as well as the roadway maintenance costs. Furthermore, a roof fall accident occurred in nearby drilling site. The investigation indicated insufficient support provided for the roadways which imposed significant safety hazards and would have serious impact to mining production and subsequent mining activities.The support of the main roadways is a critical task and is the focus of the underground opening excavation work at the mine, since more than 40 years of service life is required from these main roadways. For these roadways, large cross sections with high degree of stability and minimal amount of deformation should be maintained. Therefore, providing sufficient and appropriate roadway supports is of significant importance to the coal mine. In this paper, in order to optimize the roadway supporting system, studies were carried out on the geological structures, lithological characters, roof bolt anchoring features and suitable anchoring layers. The studies were aimed at ensuring the stability of mine roadways, reducing the roadway maintenance costs and providing a safe mine passageway for orderly production and progressive development of the mine"

Jan 1, 2016

By Grażyna Dzik, Adam Mirek, Krzysztof Król

The Upper Silesian Coal Basin is located in the area of the Upper Silesian Syncline and belongs to one of the most complex tectonic units in Europe. It occupies 5,650 km2. In 2020, there were 20 hard coal mines operating in the area. Seismological research in this area consists of observation of precursors/symptoms of shock generation and understanding of their effects. Studies (Teisseyre R. 1972, Mutke G. & Stec K. 1997, Stec K. 2007, Dubiński J. & other 2010, Idziak A. 2010) of complex impacts of rock mass provided a background for determining the conditions for the formation of exploitation and regional seismic shocks. Issues related to tectonic and exploitation stresses, successive extraction of coal seams at higher depths, operation in the vicinity of fault zones, often complex geological and organic conditions result in the activation of a discontinuity surface due to stress caused by deformation of rock layers, which, as a result, causes the emergence of strong shocks above 107 J. The article was based on analyses of extraction value, high-energy shocks, both of mining and tectonic-mining (so-called regional shocks) origin, against the background of changing operating conditions, which, as a result, creates an image of periodically changing seismic activity and location of strong shocks. Observation results show that, with an increase in exploitation depth and declining extraction, the number of strong shocks caused by tectonic stress (107 - 109 J) and exploitation stress (≥105 J) has been steadily increasing over the last 25 years.

Apr 26, 2022

By Trenton Cohen, Joseph McDivitt, Shimi Tzobery, Joseph Sinacori, Scott Zylstra

The 2-mile Beach Interceptor Sewer Tunnel was constructed in 1954 to then-current mining and construction standards. Due to its lifespan and deteriorating condition it is now being stabilized and rehabilitated using conventional excavation and ground support. At its southern end, below the prestigious Three Arch Bay community, the original tunnel alignment passes under a historic landslide where the tunnel was sand-backfilled and capped by bulkheads in 1957 due to severe and caving ground conditions. Video footage of the existing 21- inch clay pipe showed that the pipe is severely damaged, which could potentially cause a catastrophic pipeline failure and sewage spill into the Pacific Ocean. This paper summarizes the thorough investigation and design process, tunnel realignment construction and monitoring, and the notable cooperation between all parties to overcome the project risks.

Dec 1, 2022

By Jeff Fontana, Daniel Ebin, Eric Westergren, William Currier

The PMott MacDonaldlane Train Tunnel West Extension (PTTWE) Project at HartsfieldJackson Atlanta International Airport includes the extension of the existing automated people mover system and terminal renovations at the baggage claim station. To assist with design, pricing, and assessment of risk on this progressive design-build project, 3D design models were prepared to increase visibility into realities of construction. This paper will focus on the original intent of the models and explore the additional, unforeseen value they provided throughout the design and construction process.

Dec 1, 2022

By V. E. Housman

EPA's Office of Solid Waste (OSW) is developing a program, under Subtitle D of the Resource Conservation and Recovery Act (RCRA) to regulate the management of non-coal mining wastes. In May 1988. OSW produced a "Strawman", which is a working document that is precursor to a proposed rule. OSW has been working closely with environmental groups, industry, and States to solicit comments and feedback on the mining waste program. OSW currently plans to release a second "Strawman" in early 1990. A proposed rule is tentatively scheduled to be published in the spring of 1991.

Jan 1, 1990

By Yiming Sun, John Stolz, Jakob Walter, Drew Mason

The Courthouse Commons SEM Tunnel was excavated within 6 feet of cover beneath two buildings in downtown San Diego utilizing high-precision geotechnical instrumentation. The excavated dimensions are approximately 25 feet in diameter and 328 feet in length connecting two in-service detentionlevel security buildings. Presupport includes large-diameter grouted canopy pipes and smaller pipe spiles. Initial support consists of fiber-reinforced shotcrete with lattice girders. This paper presents observed ground and structure behavior and lessons learned. During construction an unanticipated brick structure was encountered, and methods were developed to improve adhesion of shotcrete to sandy soil and to reduce rebound

Dec 1, 2022

By M. Trim, Y. Sun, D. Tepavac, A. Kumar

Configuration of Rozelle Interchange Project’s ventilation system required design and construction of some of the largest and tallest underground civil caverns attempted in Australia. The paper focuses on the technical challenges of designing these caverns within a heterogeneous, generally weak sandstone under highstress conditions while providing a construction sequence that would align with the contractor’s preferred techniques and schedule. Various construction techniques were investigated, but ultimately an observational approach relying on a construction sequence and specialized instrumentation met both the designer’s and contractor’s requirements. Relevant data obtained from excavations and the construction monitoring program are presented within.

Dec 1, 2022

By V. O. Tenorio, K. W. B. Requist

As the mining industry begins efforts to examine the feasibility of extraterrestrial resource utilization, the extraction and processing of icy regolith containing water and other volatile materials will be the initial focus for future expansion of capabilities. Pure water is essential for human consumption, and a source of oxygen and hydrogen. The latter, along with the volatile materials, lend themselves to the creation of fuels that may be used for further space exploration at distances not currently feasible. For any extraterrestrial scoping project, the transport of materials to geoscientists remains virtually impossible. Therefore, analysis must be done in-situ, possibly millions of miles away from the nearest human. To address the need for geologic resource estimation in the absence of geoscientists, an infrared framework has been developed for the analysis of water ice content in simulants of permanently shaded lunar regolith. This framework relies on a convolutional neural network model for the rapid analysis of percent water ice content in samples, at which point standard geostatistical methods may be employed.

Feb 1, 2023

By Theodore Feldsher, Seung Han Kim, Mourad Attalla, John Roadifer, Chu-Chieh Jay Lin

Lifelines in seismic regions of the world seldom can escape crossing active faults. Cities in California have been mitigating this risk by constructing improved fault crossings. This paper discusses the analyses and design of the lining for a tunnel carrying a water conveyance pipeline through a fault that can potentially displace during a major earthquake event. The paper presents expected fault displacement, fault width and orientation respective to the tunnel, characterization of the ground surrounding the tunnel and its interaction with the lining, and performance required of the lining. Several other fault crossings will also be presented and discussed

Dec 1, 2022

By J. Pancher

"Stainless steel castings are used in abundance in the mineral processing industry. In rotary kiln-based processes, these castings are typically exposed to high loads, corrosive elements, mechanical abrasion and cyclical temperature exposure. In the processing of iron ore pellets, it is typical to use a traveling grate preheater or a straight grate furnace to heat the pellets. Both machines have a conveyor that is mainly comprised of high temperature stainless steel castings. It is these castings which are the focus of this study. The expected life of these castings can be quite short, their cost quite high and the effort to replace them very labor intensive. The goal of this study was to gain a better understanding of the failure modes of these castings. With that basic understanding, modifications to the alloy content could be made to achieve a new operational paradigm. That paradigm could be a cheaper casting, a longer lasting casting or a casting tailored to special operating conditions (for example, highly corrosive gases or sudden temperature shocks). Over the past 4 years, Metso Minerals has sought to achieve a better understanding of the failure modes through modeling, laboratory testing and sampling of used castings from various end-users. In addition, we have tested new alloys in a laboratory setting and also in the field to see how they would perform compared to the existing ""standard casting"". Our testing has revealed interesting data concerning the impact toughness, sigma phase content and formation, chloride attack and other performance attributes of various grades of stainless steel when exposed to cyclical temperatures. Interesting results were also obtained concerning the addition of rare earth elements (Niobium, Boron, etc), nitrogen and manganese to a typical ASTM A297 grade of stainless steel. To date, a few hundred test castings have been installed in iron ore pellet plants worldwide. Many of these test castings have already experienced a year or more of operation with good results.INTRODUCTION Cast stainless steels (ASTM A297 and similar) are a main constituent used in the construction of iron ore pelletizing equipment. A typical straight grate pelletizing machine would contain upwards of 160,000lbs of ASTM A297 Grade HH castings. With a typical casting lasting only two to four years, and a casting costing around $35USD, it is easy to see that the castings are a main contributor to the overall cost of producing the pellets. Grade HH and HI (see chemical composition listed below) became the “go to” materials in the 1960’s and very few changes have been made to this day (the exception being plants that switched to flux pellet production in the 1980’s)."

Jan 1, 2015

By Rainer Antretter

The city of Garmisch-Partenkirchen in southern Germany is located at a main transit road to Tyrol in Austria and suffers of a very heavy traffic load. Therefore, the Kramertunnel as a by-pass tunnel is built to release/mitigate the traffic through the city centre. The 3,600 m long single tube road tunnel is designed with a parallel but smaller emergency tunnel and with cross passages, fitted with single- and doublesided emergency bays, a vent shaft, and an intermediate ceiling to separate fresh air supply from the road traffic. The tunnel, concrete lined along its entire length provided the challenge to find smart formwork solutions for quick set-up, repositioning, setup and pouring. Three particularly specific sections are discussed in this paper.

Jun 13, 2023

By S. Khoshjavan

Separation of refractory rock phosphate (P2O5 = 11.5%) from the Dalir area, Iran, containing quartz, calcite and other impurities, by calcination and flotation processes has been successfully used to upgrade the phosphate values. Petrographic studies of this ore showed that collophanite was the major phosphate mineral and the main gangue minerals were calcite, dolomite and quartz. The results of characterization studies showed that the liberation degree of apatite occurred below the average grain size of 140 µm. Preliminary flotation tests were used to process the phosphate samples. Results of preliminary flotation tests showed that they don?t contain any desirable efficiency (grade or recovery) of P2O5. Calcination was the best process for preconcentration of this ore. In the desliming stage, about 14.4% of total P2O5 was removed. Encouraging concentrate grades were obtained after flotation with anionic and cationic flotation, successively. The reagent schemes that have been used in this study consisted of COCO-amine acetate and fatty acid as silicate and apatite collectors, respectively, as well as fuel oil and anionic poly acryl amid as promoter collectors. The optimum pH values for direct and reverse flotations of phosphate were 11 and 6, respectively. Experiments conducted using d80=140 µm deslimed fractions has yielded an acceptable grade of more than 30% P2O5 with a recovery of more than 62%. Finally, a laboratory flowsheet for the processing of Dalir refractory phosphate ore has been proposed.

Jan 1, 2011

By Christopher Mark

Area wide pillar failures, or “squeezes,” were once fairly common in underground coal mines. While rare today, they do occur. This paper describes seven case histories that were investigated by MSHA Technical Support. They occurred across the range of US coalfields, in both longwall and room-and-pillar mines, and involved development mining, pillar recovery, longwall panel extraction, and multiple seam interactions. Significant lessons from each are discussed.

Jun 25, 2024

By Lana Alagha, Keitumetse Cathrine Monyake

The abstract discusses the synthesis and investigation of polyacrylamide functionalized chitosan polymers (CS-PAMs) as selective depressants for pyrite in the flotation of galena and chalcopyrite from complex sulfide ore. The study employed response surface methodology (RSM) to model and optimize the flotation process, varying parameters like the degree of deacetylation of chitosan, weight ratio of chitosan to acrylamide, and CS-PAM dosage. The developed RSM models effectively predicted iron and lead grades and recoveries, while optimization showed optimal pyrite separation from galena and chalcopyrite using CS-PAM synthesized from chitosan with a high degree of deacetylation and a specific chitosan:acrylamide weight ratio.

Apr 9, 2022