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By Jiachen Wang, Nan Wang, Yang Li

The close-multiple coal seam is an important component of China’s coal resources and plays a key role in total coal reserves. However, the overburden movement in the mining process of close-multiple coal seams is usually extensive, which is seriously affected by overmining. It is therefore essential to study the mechanism of roof breakage, the relationship between the shield and the surrounding rock, and the mechanism of overburden movement to ensure the safe operation and the efficient exploitation of close-multiple coal seams. This work first proposes a technical route for intelligent ground control. Second, the principle of cooperative control between the shield and overburden roof is revealed, and the shield support capacity calculation method is summarized. Third, the quantitative criterion for disturbance degree of key stratum (KSDD) is proposed based on the key strata theory. Finally, several intelligent evaluation and analysis systems have been developed in terms of overburden breakage and shield support capacity, multi-information analysis of ground control, and disturbance degree of overburden. The research results may provide an essential reference for the development of intelligent ground control in the mining process of close-multiple coal seams

Jul 1, 2023

By Jun Li, Marc Le Vier, Rong Yu Wan, Jan D. Miller

The hydrometallurgical treatment of gold and silver ores by ammoniacal thiosulfate solutions in the presence of a copper catalyst has been actively studied in recent years. Such a process strategy is very attractive due to the low toxicity of the lixiviant and the efficient recovery of the precious metals from difficult-to-treat ores. Important features of the ammoniacal thiosulfate system for the recovery of precious metals from various sources are reviewed in this paper, including leaching, metal recovery, and system stability.

Jan 1, 1995

By Pedro Pablo Vasquez Coronado, Victor Octavio Tenorio

"Productivity in openpit mines depends on the observation and adjustment of critical phases of operation. As one of the most expensive activities in openpit production, optimization of the load-haul-dump cycle becomes a critical aspect to address. Using simulation techniques and an ad hoc methodology for analyzing the key performance indicators (KPIs) involved in the production cycle, it is possible to compare actual performance and ideal operating conditions and develop an alert system when operating conditions are subpar with the expected production standards.Study objectivesThe purpose of this work is to implement a methodology for optimizing the haulage cycle by identifying and adjusting the factors that affect the cycle time performance. The methodology includes the implementation of an alert system emitting warning messages when one or several trucks are idle, or when the time of completing production tasks is falling outside a predefined value. This alert is compared with predefined KPIs and is used to determine corrective actions.The alert will:• Demonstrate the benefits of time analysis and how this affects the productivity results in the mining process.• Demonstrate the utility of KPIs in the extraction of ore and waste and how they help to identify equipment performance.• Develop software interfaces to visualize the alert system in order to increase awareness in the operations supervisor.• Make recommendations for future applications that can help improve the productive process of an openpit mine.Problem statementTransporting material in openpit mines may require the utilization of high capacity equipment, which also represents an elevated cost per hour. A supervisory system that controls the adequate distribution of trucks and shovels by providing the operational status of each unit shall contribute to increase productivity while subsequently reducing operational costs. Nevertheless, there is an issue with certain dead times such as queue trucks for loading, trucks waiting to be loaded and other delays. This creates inefficiencies in fuel consumption and energy utilization.For the identification of delays, a contextbased system could be required in order to help optimize the haulage cycle time by controlling delays in loading, haulage and dumping. After applying this methodology, efforts were focused in correcting out-of-standard performance values."

Jan 1, 2015

By Deepak Malhotra

Is operator training necessary for optimization of flotation plants? The answer is obvious-Yes. The author suggests a three-phase program for operators when new plants are built or new crews are hired in existing operations. Case examples are discussed to illustrate the benefits of operator training.

Jan 1, 1999

By Harold D. Stevenson, Gerald G. Carlson

The Flow-Through Shares Program was set up by the Canadian Federal Government in 1978. While initial annual expenditures in flow-through shares was small, recognition of flow-through as a significant tax advantage combined with exploration successes, particularly in the gold sector, soon resulted in the majority of exploration dollars raised in Canada utilizing the flow-through share mechanism. What Are Flow-Through Shares As many exploration companies are non-taxable, they are not in a position to benefit from the tax deductions arising out of their exploration activities. Flow-through financing provides a mechanism for the exploration company to transfer these deductions to an investor. In addition to the deductions which an investor can apply against his personal income, the investor receives common shares in the exploration company (flow-through shares). To add to the attraction, the Federal government provides a 33 1/3 percent mark-up on qualifying expenses incurred by the exploration company, giving the investor a deduction of up to $1.33 for every $1.00 invested. By providing the investor with tax deductions in addition to the flow-through shares, flow through shares can often be sold at a premium to market which makes-the mechanism attractive to the exploration company as well. These shares are often sold through private placements and therefore have to be held for one year. The tax cost of the share is deemed to be ril, so the entire proceeds on disposal are

Jan 1, 1987

By K. H. Al-Rawahy

Appreciation and awareness of the unique nature of mineral investment and ultimate development of a mine are crucial in promoting sustainable development. Special characteristics of mineral development include high capital intensive, long pre-production period, high risk, and the unavoidable ?economic? depletion. This paper examines ways to integrate these unique attributes of the mineral industry into the educational process, so that a properly advised and knowledgeable culture in terms of a sustainable mineral industry can be developed. Specific approaches are investigated in order to achieve this objective. These include a stochastic evaluation of a mineral investment proposal, adding a premium to the cost of capital that is used for valuation process, and internalizing incidental costs to the private cost function, thereby realizing the true (vs. apparent) marginal social cost of the proposed development. Undoubtedly, a total evaluation of any mineral project that accounts for both tangible and intangible parameters will contribute to sustainable development objectives. By incorporating the practical application of apparent theoretical topics such as risk, probability, and externality, and their relevance and impact on mineral lifecycle (prospecting, exploration, development, exploitation, use, and ultimate disposal) into the educational process, it is hoped that a generation of technocrats and decision makers that are familiar with and concerned about sustainable development will emerge.

Jan 1, 2007

By D. W. Rierson

Svedala has a ported kiln process, designed specifically for the direct reduction of pelletized or natural lump iron ores. The process is called ACCAR. This ported kiln technology has been coupled with Svedala's GRATE-KILN System, for iron ore pelletizing, into the GRATE-CAR System for the reduction of fine grained ore concentrates through the steps of agglomeration, induration and reduction in a single production line. Additional applications of the GRATE-CAR System include: the recovery, agglomeration and reduction of steelmill waste oxide fines and the use of minus 6mm size natural lump ores to produce a highly metallized pellet agglomerate. Svedala conducts tests to confirm certain operating parameters through process simulations of the GRATE-CAR process. These tests are conducted at Svedala's Process Research and Test Center, Oak Creek, Wisconsin. Svedala also assesses issues of process variables, heat transfer, equipment sizing, retention time and endothermic demand associated with iron ore reduction using natural gas or coal as the reductant. The purpose of this paper is to present the GRATE-CAR processing concepts, the commercial production line and the testing procedures associated with investigating potential raw materials.

Jan 1, 1997

By Yong-ping Wu

Based on the rules of strata behavior and the characteristics of rock movement, the elementary problems of using fully mechanized coal mining techniques in steeply dipping coal seams are described. A model of the "surrounding-support-rock" relationship is made. The support systems stability during fully mechanized mining of steeply dipping coal seams is studied. Then, a practical engineering example of the fully mechanized mining of a steeply dipping seam is presented. The seam used in the example is in the Lushuidong colliery, which is administrated by Huaying Mining Bureau, Sichuan Province.

Jan 1, 2003

By Tim Lundquist

Disa Technologies Inc. provides innovative, sustainable solutions for mineral processing and remediation through its patented High-Pressure Slurry Ablation (HPSA) technology. HPSA processes solid feed material in slurry form, propelled by high pressure pumps through opposing nozzles that generate impinging jets within a collision housing. This process induces particle-to-particle collisions in a high energy zone, creating intergranular fractures along grain boundaries. In our batch scale and continuous operating testing, we have found that controlling key processing variables such as nozzle velocity, slurry solids percentage, and the number of passes can allow for controlled size reduction and maximum mineral liberation. Since 2018, Disa Technologies has demonstrated the versatility of HPSA by testing it on diverse materials, including phosphate, copper, uranium, vanadium, zinc, rare earth elements, lithium, nickel, mineral sands, gold tailings, and more. The intent of this paper is to present an overview of our test results describing in detail impacts on size reduction, recovery, and grade with a focus on HPSA's adaptability across ore types. Looking forward, it explores the potential to process materials such as DR-grade iron, clay, PGMs, bauxite, and various tailings. Additionally, it examines planned advancements in HPSA technology, including optimized nozzle spacing, higher capacity models, improved tonnage-to-footprint ratios, enhanced maintenance features, and expanded nozzle configurations.

Jan 1, 2025

By J. W. Rinard

This paper is intended to introduce "non engineers" to one of the more misunderstood pump performance parameters, NPSH (Net Positive Suction Head). This basic presentation and resultant review should provide a practical understanding of NPSH and what its importance is to pump operation and reliability.

Jan 1, 1996

By Jake Coibion, Elmira Riahi, Dominic Reda, Walter Klary, Vojtech Gall

Progressive Design-Build is becoming a more common delivery method in the tunneling industry. This approach allows the Owner to select a design-builder primarily based on qualification instead of lowest price. The delivery method promotes flexibility and collaboration at all levels from the initial design stage through construction. Using the example of the Atlanta Airport Plane Train Tunnel West Extension, value-added risk management was added during the initial design phase with an independent reviewer. This paper presents the independent reviewer transitioning from constructability review in the very early stages of design to independent design verification to on-site supervision during construction.

Jun 13, 2023

By Jack G. Pippenger

This report focuses on the procedures required to review, prepare specifications, bid, and purchase a fully integrated computer system for utilization by engineering personnel in all phases of mine engineering. The presentation is based on the experiences encountered in 1984 in procuring an engineering computer system at The North American Coal Corporation's Western Divi- sion. A two-phase report detailing the purchasing process and subsequent utilization of the engineering computer system will be given. Special detail is also provided on the final system hardware and software setup.

Jan 1, 1989

By Gerhard Lang

"Slurry Microtunneling is a well-established technology building on over 20 years of experience in successful tunnel installations under all kinds of soil conditions across the U.S. and Canada. Recent microtunnel installations prove that initial hesitation, e.g. curved drives, is fading and long-distance pipe jacking projects as well as lake outfalls are being considered. One of the younger technologies is Direct Pipe®, which combines the benefits of HDD and Slurry Microtunneling. It fits exactly into the area where HDD is not feasible or too risky to apply. The paper points out the benefits of the Direct Pipe® technology for owners, engineers and contractors and discusses the latest developments of Slurry Microtunneling for long-distance, curved drives and sea/lake outfalls with wet recovery of the equipment such as on the ‘Keswick Outfall Project’ in Ontario. The first Direct Pipe® installation in the US was executed in August 2010. Since then, another 22 crossings have been carried out amongst a total of more than 60 Direct Pipe® crossings worldwide. INTRODUCTION Pipelines installed underground are indispensable for supplying the growing world population with water, oil, gas and electricity, for removing wastewater and for providing functioning telephone and communications networks. During recent years the limits of trenchless applications have been permanently shifted, leading to higher and more stringent project requirements and consequently new technologies, either as further development of existing methods, or through the development of new methods by incorporating elements of proven technologies. MICROTUNNELING TRENDS IN NORTH AMERICA Slurry Microtunneling has a wider geological application range in comparison to EPB and hard rock Microtunneling. The Slurry MTBM can be equipped with specific cutting wheels to cope with different soil conditions. The most flexible and most often employed type is the mixed soil cutting wheel, which contains a mixture of disc cutters as well as scrapers for varying soil conditions from cohesive soils (clay, silts) to highly permeable soils including sands, gravels and cobbles and even hard ground formations such as rock and boulders. A detailed geotechnical report provides the appropriate data to configure the MTBM and its features to the ground conditions expected. Mixshield or hydroshield (AVN/AVND) MTBMs in particular, can be safely operated with little overburden (~ 3-5 x machine diameter) and minimum risk of frac-out or settlement on the surface. This is especially beneficial in urban areas with sensitive buildings or for river crossings with protected fish habitats."

Jan 1, 2016

By W. H. Langer

The U.S. Geological Survey (USGS) in cooperation with the New Mexico Bureau of Mines is conducting an assessment of mineral resources in the 36,800 km2 Mimbres Resource Area, southwestern New Mexico. Included in the assessment is a literature-based evaluation of sand and gravel that utilizes third party geologic information. The USGS has developed a method based on existing 1:500,000 scale geologic maps supplemented by remote sensing, statistical models, and point data such as test hole or pit records. The method defines the areal extent, quality, and quantity of aggregate.

Jan 1, 1996

By D. M. Fritz

Environmental experts face large and rapidly-increasing volumes of raw data obtained from environmental monitoring stations. These professionals must compile and analyze the data in a systematic manner to cost-effectively understand and minimize the impacts of mining. The shift toward desktop computing, combined with the downsizing of company staffs, has now more than ever created a demand for a modern, PC-based application for the storage, retrieval, analysis and presentation of environmental data. This paper discusses the general requirements of such a system, and points out specific ways in which such industry-specific software can provide convenient and useful access to the data. The software used to illustrate these features is the HydroDat program, developed by Western Water Consultants, Inc.

Jan 1, 1996

By James O. Mawyer

Fuel is a major .cost for power generating utilities. Virginia Power is completing one of the nation's largest coal reconversion programs. As a result, 10 million tons of coal will now be used at six generating stations. Four of these stations are located on naviagable waterways. They consume over half of Virginia Power's coal. Historically, railroads have exclusively served these plants. In an effort to substantially reduce fuel cost, Virginia Power has reexamined transportation logistics and is proceeding with barge delivery. A phased approach was used by Virginia Power for the transportation program. Plant requirements were first identified. Coal sourcing issues were then examined. The concept of intermodal transportation was investigated. The bottom line cost savings was used as the criteria for continuing the project. The results thus far have been gratifying. Virginia Power has begun to implement barge transportation.

Jan 1, 1986

By T. J. Harvey, W. van der Merwe, J. Joubert

GeoBiotics, LLC and Kumba Resources (Pty) Ltd are jointly developing the GEOCOAT® heap bioleaching technology and downstream processing technology for recovery of zinc from tailings at the Rosh Pinah Mine in Namibia. This paper outlines the development of a computer simulation for the bioleaching of sphalerite and the downstream processing. Computer modeling has shortened the product development cycle by allowing many flowsheet scenarios to be analyzed negating much of the expensive and time consuming laboratory testing. A model was developed using the Limn® system which is an Excel® Add-In flowsheet drawing and solution engine. Given that most engineers are familiar with Excel® this software is extremely easy to use and has less hidden calculations making model verification much easier.

Jan 1, 2003

By J. L. Weeks

Discussion by J.L. Weeks Discussion I wish to comment on Kissell and Sacks's paper "Inaccuracy of area sampling for measuring the dust exposure of mining machine operators in coal mines." It is well established in industrial hygiene that area sampling is not an accurate measure of personal exposure. To measure personal exposure, one must use a personal sampler. Kissell and Sacks, using data from coal mining, reached the same conclusion. This is the right answer but it is the wrong question. This issue arises because the machine-mounted respirable dust continuous monitor (MMRDCM) is being considered to monitor coal-miners' exposure to respirable dust. This device may be mounted on a continuous mining machine, and it would take a modified area sample. I refer to it as "modified" because a mining machine is not really a fixed location, as is the typical area sample. The concern with whether this machine would provide an accurate estimate of the machine-operator's exposure, however, overlooks important features of the MMRDCM. Specifically, it displays dust concentration as it occurs and at the place where it is needed, not 10 days later, as is the case with the current system. Used in this way, it allows for timely intervention to control exposure to dust and it leads to greater first-hand knowledge of specific conditions and mining practices that result in excess exposure. If one knows the dust level is excessive at the time the dust is being generated, it is possible to use known and effective methods of dust control to reduce exposure. By measuring again, one can determine whether control methods have worked. This is a generic procedure followed in any industrial process: measure, adjust and measure again. It leads to more effective and more efficient dust control and is preferred to taking a sample, waiting 10 days for the results and then trying to apply that information to a situation that no longer exists. The MMRDCM also records the dust level automatically, and it runs continuously, making it harder to tamper with. Dust monitoring in underground coal mines has been corrupted by some operators having submitted fraudulent samples (and being convicted on criminal charges because of it), weakening the credibility of the current system. The MMRDCM is, in part, a response to this corruption, and an effort to focus attention on dust levels and dust controls rather than on the perpetrators of fraud. Use of the MMRDCM is an evolutionary change from the current system. With the current system, one takes a personal sample of exposure of the "designated occupation" (DO, defined at 30 CFR 70.2 (f)), the occupation regularly exposed to the highest level of dust on a section. Typically, on sections using continuous mining machines, this is the mining-machine operator. The rationale behind DO sampling rests on some of the findings that Kissell and Sacks report. They reviewed several studies that showed that dust concentration varies with location on a mining section and that there is a concentration gradient with the highest concentration occurring closest to the face. The logic behind DO sampling strategy is that if the dust concentration at the place where it is highest is below the exposure limit, then concentration elsewhere on the section is also below the limit. In this way, one will have achieved the objective or keeping dust concentration below the exposure limit for all miners on the section by measuring the exposure of only one miner. The

Jan 1, 2003

By O. J. R. Baena

Mining activity in the Segovia region in NE Colombia is the main source of employment in the local economy. This has created major problems of illegality and informality mining associated with a high social and environmental impact, as inefficient technologies are used and high consumption of toxic substances required in the process of gold recovery by amalgamation and cyanidation. In this work is presented mineralogical characterization of six local mills and studied beneficiation processes developed in them. With the results presented a proposed plant design that eliminates the use of mercury by replacing gravity concentration processes taking advantage of the characteristics of the treated material. Significant results were obtained regarding the recovery of precious metals and present a methodology that can be replicated in other mineral beneficiation plants that use gold amalgamation processes. This implies a significant reduction in mercury use and decreased risk of human contamination associated with this.

Feb 23, 2014

By D. L. Moellenberg

Under various state laws enacted mostly within the last 20 years, reclamation requirements and standards for hard-rock mining operations have been established virtually everywhere in the western United States. Unlike the uniform and detailed coal mine reclamation requirements under the federal Surface Mining Control and Reclamation Act ( "SMCRA" ) and state programs mode led after SMCRA, the various state law hard-rock mine reclamation requirements are based upon a variety of objectives, and therefore are subject to varying standards from state to state. While the diversity of reclamation requirements complicates the determination of what reclamation measures will be required at any particular mine, there are valid reasons for this diversity. There are dozens of different commodities mined in the United States, and mining methods are different for each commodity. Local natural conditions such as climate, precipitation, geology, hydrology, and biology vary widely across the county. Site-specific conditions also affect mining and reclamation methods. Also, factors such as economics, land use, and environmental protection issues receive different priorities in different states and communities within those states. State reclamation requirements in general provide the flexibility to consider site-specific circumstances, allowing operators to design and engineer the best reclamation measures for each mining site. To the mine developer or manager, reclamation requirements must be translated into design, operational, and closure measures for mine planning. Each of these measures must then be assigned additional costs to be factored into the economic decisions for a particular mining operation. On a broader level, reclamation costs must be factored into decisions such as where to invest in exploration and mine development. The purpose of this paper is to provide a summary of the state non-coal mine reclamation requirements in twelve western states. This summary comparison may be useful as a starting point in considering how local reclamation requirements will impact potential mining costs.

Jan 1, 1994