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By Dae Young Kim, Sim Bo Kyung, Ebrahim Farrokh, Ki Chang Hyun

"TBM cutter life evaluation in abrasive granitic rocks is a very important issue, especially in pressurized face tunneling with mixshield TBM for which the planning of costly interventions becomes crucial. This paper presents an overview of methodologies for cutter life evaluation in rock. A comparative study is performed to indicate the predictability of cutter life evaluation methods based on detail data from the NS3 tunnel project in Singapore. A new model is developed based upon the cutter wear information of eight TBM tunnels from around the world. New methods are proposed to evaluate the optimum intervention interval length and the number of worn-out disc cutters for a tunnel project. Finally, two new laboratory tests in the evaluation of disc cutter abrasion, including a full-scale and a small-scale test, are introduced, and their test results are discussed. INTRODUCTION The issue of wear evaluation for hard rocks has been extensively studied in drilling and pavement industry. In this regard, several tests and evaluation methods have been proposed to estimate or evaluate the state of tool life (e.g. bit life for drilling). In the case of TBM tunneling, tool wear may depend on several factors such as mineral composition, strength, or type of cutting, but as the abrasion is usually the major mechanism for the tool wear in hard rock, the developed methods for cutter wear or cutter life evaluation are mostly based on the abrasion indices such as Cerchar Abrasivity Index (CAI). This paper attempts to review the major methodologies for disc cutter wear and life evaluation and to propose new methods to evaluate cutter life and intervention interval evaluation based on detail information of a mixshield tunnel project in Singapore as well as general information of some other projects from Iran, Italy, South Africa, and France. As the laboratory tests are crucial in the process of evaluation, two new lab tests are developed and used to inspect suitability of the new proposed model for disc cutter wear evaluation."

Jan 1, 2016

By G. L. Mowrey

A new coal interface detection (CID) method is under investigation by the U.S. Bureau of Mines. This novel concept is based on utilizing a passive infrared system (FIR) to measure temperature changes associated with the cutting of coal and adjacent strata. For this method to work successfully, a definite mechanical/hardness contrast must exist between coal and rock. Advantages include that FIR responds instantaneously at the coal-rock interface and it is minimally affected by dust and/or water sprays. Based on preliminary tests, results indicate that the PIR method can be applied successfully in mines having a hard immediate roof.

Jan 1, 1990

By R. Benemelis

The existence of resins in some coal deposits in various parts of the world has been known for many years. These resins vary considerably in chemical structure and properties. The resin that is found in Utah coal, however, is rather unique, and has properties particularly attractive for the manufacture of printing ink mastics and adhesives. This resin is a rather dark, very high melting point, low molecular weight hydrocarbon resin. Its typical properties are shown in Table I. Its largest use by far, has been in the printing ink industry. The history of Utah coal resin is interesting, but unfortunately one of disappointment and failure.

Jan 1, 1990

By Yongsik Jeong, Kwangmin Kim

Conventional tailings slurry contains a significant amount of water, and water management is key to ensuring the stability of a tailings storage facility (TSF). Simply reducing the water content in the slurry before discharging it from the mill could be an effective way to improve TSF water management. This study investigated the potential for using an environmentally friendly polymer as a new drag reduction agent (DRA) to reduce frictional pressure loss and also conserve water. It entailed conducting pipe loop tests to assess the polymer’s effect on pressure loss in tailings flow and then applying the test results to validate a numerical model using computational fluid dynamics (CFD). The model was also used to determine the polymer’s optimal concentrations at given solid concentrations and flow rates, its effect on energy efficiency for tailings transportation, and its potential for saving water. A case study for a mid-sized, hard-rock mine with a throughput of 50,000 t/day found that the solid concentration could be increased from 30 to 45% with no pressure loss by applying 1996 m3 of the polymer per day. Adding the polymer also resulted in water savings of 57,552 m3/day. The results of this study demonstrated the potential for using the new DRA not only to improve TSF stability but also to save water.

Jun 29, 2020

By İsmail İnce

The purpose of this study is to investigate the index-mechanical properties of igneous rocks by using the electrical resistivity method. Electrical resistivity, index (P-wave velocity, dry density, and porosity), and uniaxial compressive strength values of 48 different igneous rock samples were measured in the laboratory. Simple regression analysis was performed between index-mechanical properties and electrical resistivity values. Strong exponential and logarithmic correlations were found between electrical resistivity and the index-mechanical properties of the igneous rock samples.

Jan 21, 2022

By Donald G. Rogich

The concept of initiating a large action-oriented contract, directed toward inherently safe mining systems, was conceived by the U. S. Bureau of Mines in January 1970. At that time we were in the process of establishing research contracts and grants, about 100 of which were let in FY 71 to deal individually with fairly specific technological areas. These projects in the aggregate covered a wide spectrum of health and safety problems. What appeared to be necessary was the creation of a project or program that would provide a focal point for the demonstration of many of the results of this research and also in the action sense culminate with working hardware and systems that could be tested and demonstrated over a fairly long teen. The concept of working demonstrable systems, rather than just a conceptual study, was, felt to be necessary for two significant reasons. In the development of any new system, the translation from concept to working hardware is usually a costly and time consuming process which acts as a deterrent to implementation. Secondly, many decisions in the mining community to change equipment or systems ,are based on first hand observation of the new system, in operational practice, an attitude which is certainly understandable in view of the high capital costs of equipment. The decision was made to procure a single R&D contract which would be aimed at developing underground coal mining systems which

Jan 1, 1972

By R. J. Roman

The "mass balance" is unquestionably the most common class of problems for the process engineer'. Closely related, mathematically, is the "heat balance". Every laboratory test requires a mass balance to describe the results. Mass balance calculations can be subdivided into several sub-categories based on whether the results are time dependant or not and depending on whether the input data are measurements that contain errors or are hypothetical values with no errors. Time dependent mass balances are dynamic process simulations and in addition to the conservation of mass constraints require kinetic data input. They are one step beyond simple mass balances.

Jan 1, 1992

By Thomas F. Joyce

N L Industries, Inc., MacIntyre Development produces ilmenite and magnetite concentrates from its own open pit operation at Tahawus in New York's Adirondack Mountain region. The ilmenite concentrate is used within the company for the production of titanium dioxide pigments and the magnetite concentrate is sold to heavy media processors. Current production is from South Extension mine, loading by by six-yard Marion electric shovels into 85 ton Lectra Haul trucks. Bench heights are 44' and are drilled with a Robbins Rotary 9 7/8" diameter hole on 25' spacing for a yearly production of 3.4 million total tons of rock. The ore deposit occurs in veins dipping on the average at 40 degrees to the west. The ore body, which is divided into three zones, outcrops at surface and continues to depths of 800'. Zone 1 is a high grade band of thickness 150-200' with an Fe/Tio2 ratio of 2. Below this band is Zone 2, a low grade band of thickness 50-100' with an Fe/Tio2 ratio of 2 and beneath that seperated by a band of anorthosite is Zone 3, a high grade band of irregular thickness 50-450' with an Fe/Tio2 ratio of 1.6.

Jan 1, 1973

By M. S. Moats, W. C. Hartzell

The stable domestic supply of gallium, indium, and germanium has been identified as a critical need for the United States. Electric arc furnace dusts, processed to recover zinc, produce a residue that could be a potential source of these critical materials. An industrial zinc leach residue was characterized to determine its particle size, chemical composition, and predominant mineral phases. Heated, atmospheric, agitated leaching using sulfuric acid and hydrochloric acid was examined to determine the extractions of gallium, indium, and germanium as a function of concentration and temperature. Extractions of gallium were found to be similar to iron in all experiments. The maximum percentage of Ga, Ge, and In leached into solution were 71%, 63%, and 48%, respectively.

Feb 1, 2023

By Y. H. Zhan

A new P(MAAA) latex was developed and used in separation of ultrafine apatite from calcite and silica by means of selective flocculation. The latex was found to flocculate selectively apatite from apatite/calcite and apatite/silica mixtures in the presence of sodium tripolyphosphate and sodium silicate over a pH range from 9.1 to 9.4. The separation of apatite from calcite was more selective with sodium tripolyphosphate, while the results of the separation of apatite from silica were better when sodium silicate was used. In the apatite/calcite system, 90% apatite recoveries into a concentrate containing 34% P2O5 were possible in the presence of 4 mg/l of sodium tripolyphosphate at a latex dosage of 2.2 kg/t. In the apatite/silica system, 80% of apatite could be recovered into a concentrate containing 33% P2O5 in the presence of 20 mg/l of sodium silicate at a latex dosage of 1.1 kg/t. Deposition tests were used to study the interaction between the latex and the mineral surfaces. The results revealed that deposition density of the latex on apatite was higher than on calcite; the differences between the deposition onto these two minerals were higher at pH 9.2 than at 7.2. The results point to the stronger interaction between the latex and apatite surface when compared with the latex-calcite interactions.

Jan 1, 1998

By Michael A. Redfearn

The use of nitrogen in molybdenite flotation circuits is a relatively new concept utilized by only a few mines around the world. This paper briefly discusses circuit chemistry and the reason for its success. It follows the entire testing process which resulted in a sodium hydro-sulphide dosage reduction from 18.5 to 4.4 lbs/ ton (9250 to 2200 g/t) through to the final installation of an inert gas generator which will produce reagent savings in excess of one million dollars annually. A description of the various types of nitrogen generators commercially available is included.

Jan 1, 1983

By J. A. Domenico

A safe and precise mineral separation alternative to heavy liquids is being used for mineral sands exploration on large scale orebodies. The separation process, Magstream®, uses ferro-fluids and magnetic and centrifugal forces to produce precise split points over a range of specific gravities from 1.5 to 18.0 g/cc. This paper describes a commercial scale exploration program treating, roughly, 90 samples per day in Senegal (West Africa). Separation results comparing Magstream® and conventional heavy-liquid separation are presented.

Jan 1, 1994

By Juan L. Yarmuch, Gonzalo Sepulveda

This article presents a novel approach to address the mining width-constrained open pit mine production scheduling problem in the context of medium-term planning. A mathematical formulation is proposed to incorporate mining width constraints into the production scheduling process, aiming to maximize the NPV of the schedule while ensuring enough room for the operation of mining equipment. To tackle the computational challenges posed by large-scale instances of the problem, we propose a method based on variable fixing and horizontal precedence generation. In this study, we apply the developed model to real-world scenarios from Radomiro Tomic short-term mine planning problems such as optimizing the timing of major truck maintenance and the impact of external factors, like the delay in the production of the Chuquicamata underground project. Remarkable improvements are observed with the mining width-constrained model. Specifically, the mining width satisfiability is enhanced from 2 to 60% compared to the traditional open pit mine production scheduling model, underscoring the significance of incorporating these constraints. The proposed method showed good results reaching optimality gaps within 5%.

Mar 28, 2024

By J. G. Groppo

The Andritz Ruthner Inc. hyperbaric filter was evaluated at a pilot scale for dewatering fine coal cleaned by froth flotation. The pilot scale dewatering testing was conducted at a solid feed rate ranging from 100 lbs to 200 lbs/hr-ft2. Effect of hyperbaric operating parameters and addition of various surfactants and flocculants were evaluated on dewatering of fine coal. The tests data indicated that for the minus 100 mesh and minus 28 mesh clean coal product, the Andritz hyperbaric unit provided filter cake containing 23 percent and 14 percent moisture, respectively.

Jan 1, 1996

By Vas P. Srinivasa

A comminution circuit is an important integral part of a mineral processing plant. Nearly 40% of the capital cost and 30 to 40% of the operating cost are taken up by the crushing and grinding circuit. Therefore, considerable care should be given to the design and selection of this circuit. Several factors affect the selection of a comminution circuit--energy consumption, avail- ability of the equipment, the remoteness of location, and availability of trained personnel, to mention a few. Each of these factors influences the choice. Selecting a comminution circuit strictly on lower capital cost may not be optimal. Crushing and grinding circuits are usually site specific and should be selected - only after careful analysis of all the factors involved. The objective of this paper is to show the effect of these factors, which are extranious to capital cost. Usually, the capital cost of a semiautogenous grinding circuit is lower than that of an equivalent conventional circuit. However, due to lower equipment availability and high power costs in certain locations, the economic advantage of lower capital cost is lost. Analysis indicates that a break even point occurs at a power cost of 5¢/kWh. This paper describes the procedure utilized for selecting the most economic comminution circuit and states the conditions applicable for each cominution circuit.

Jan 1, 1983

By B. A. Ashley

In 2007, Rosebud Mining Company (RMC) opted to extend the reserve base of Tracy Lynne Mine by developing through a sandstone channel. The extension provided access to approximately 6 million additional recoverable tons (approximately 8 years of mining) which originally had been deemed inaccessible. An evaluation of the mine?s existing ventilation system, which was designed to meet the needs of the original limited reserve, concluded that two ventilation shafts would likely be required to adequately ventilate the projected workings in the expanded reserve. To assist in the evaluation, a ventilation model of the mine was developed using Ohio Automation?s ?ICAMPS MineVent? software based on field data from Tracy Lynne Mine, prior ventilation survey experience at similar RMC mines, and relevant published sources. Model results suggested that the most economical shafts would be an 8-ft diameter return and a 4-ft diameter intake. Unfortunately, issues related to property leasing and shaft site permitting caused construction delays. Therefore, the model was also used and proved to be effective in prioritizing interim ventilation upgrades which could be implemented in order to maintain coal production. Model results indicated that the best interim upgrades included rehabilitating restricted entries and damaged stoppings and replacing the main fan with a higher pressure fan. From late 2010 to mid-2012, all interim upgrades and shafts were implemented. Current models and mine experience indicate that ventilation will not be the limiting factor for mining the additional reserve.

Feb 23, 2014

By D. R. Nagaraj

Secondary Ion Mass Spectroscopy (SIMS) was used to study copper ion adsorption, and its effect on subsequent sulfide collector adsorption, on pyrite and pyroxene minerals under flotation related conditions. Copper was found to adsorb on both of these minerals and cause enhanced sulfide collector adsorption. The distribution and depth profile of copper and collector on these mineral surfaces were obtained by using SIMS in the imaging mode. The results of this study have provided a valuable insight to understanding pyrite and gangue flotation observed frequently in operating plants.

Jan 1, 1995

By L. Xu

Since the establishment of the standard dust concentration of 2 mg/m3, a strong effort has been made by mining engineers and researchers to provide better dust control equipment and procedures for underground coal mines. Particular areas of success have been control of dust generation by better coal-cutting strategy, better design of water sprays for dust suppression and air movement, use of scrubbers, and improved design of face ventilation systems. A drastic improvement occurred over time such that the average dust concentrations for continuous miner operators dropped from 6.5 mg/m3 in 1968 to 1.3 mg/m3 in 1980 and for auger, cutter, longwall, and roof bolter occupations from 2.7 mg/m3 in 1973 to 1.6 mg/m3 in 1980 (Niewiadomsky, 1983).

Jan 1, 1990

By Steven J. Schatzel, James Addis, K. Vaibhav Raj, Berk Tulu

The National Institute for Occupational Safety and Health (NIOSH) is conducting research to enhance methane control and mine ventilation practices at coal mines, as a method to mitigate hazardous work conditions. NIOSH researchers conducted case studies to investigate the effectiveness of existing systems and improve performance to decrease the potential for unplanned or excessive methane emissions. At one mine, drainage was influenced by hydrofracking inefficiencies where two of the six wells showed good frack development. Methane content was variable, from 300 ft3/t to 600 ft3/t. This paper also summarizes overburden movement during undermining and the estimated quantities of gas transported to the mine using FLAC3D and CFD modeling. The findings from this research effort highlight considerations based on specific mine conditions that may also be applicable to most longwall mines utilizing methane control systems.

Feb 1, 2025

By J. A. Organiscak

Enclosed cab filtration systems are typically used on mobile mining equipment to reduce miners? exposure to airborne dusts and diesel particulates generated during mining operations. Various filter configurations can be used within the heating, ventilation, and air conditioning (HVAC) systems of cabs to remove the airborne contaminants. The air cleaning performance of cab filtration systems is highly dependent on the efficiency of the air filters, the number of filters used, and their placement within the HVAC system. This paper shows how to mathematically model cab filtration systems and illustrates a methodology for developing other cab filtration system design models. Node diagrams of several filtration system circuits are illustrated with their mathematical models at steady state airflow and concentration conditions. Laboratory and field data are presented to demonstrate the validity and utility of modeling enclosed cab air cleaning performance. The paper concludes that incorporating multiple filters throughout the HVAC system improves the air cleaning performance and robustness of the cab filtration system design.

Feb 23, 2014