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By Jian Deng, Hehua Zhu, Lianyang Zhang

Rockburst is defined as a sudden and violent explosion of rock on the surface of a rock excavation. Rockburst has been regarded as the least understood and most feared hazard problem for underground rock excavations. Traditionally, rockbursts were classified into the strain, pillar, and fault-slip categories. However, rockbursts are also known to occur at stress levels well below the rock yield strength, in mines where the rock is far from brittle, or without the presence of geological discontinuities. A plausible explanation of rockbursts is buckling, which has been identified as one of the main mechanisms for rockbursts. It is observed that rockbursts are often induced by dynamic loadings (pulses) from adjacent blasting. Therefore, the present paper studies the effect of pulse shape and amplitude on pillar rockbursts induced by dynamic loadings from blasting using the method of numerical analysis. The governing equation of a pillar’s motion is set up and the mechanism of pillar rockbursts is investigated through a practical example. The results show that it is not the shape of a pulse but the impact energy to decide the occurrence of pillar rockbursts. If all other parameters remain the same, pillar rockbursts are more likely to occur when the pulse duration is longer. The parametric resonance and the perturbation of dynamic loadings are also found to play an important role in the occurrence of rockbursts. These insights would provide invaluable clues about the mechanism and for better control of pillar rockbursts.

Apr 26, 2022

By Ilmar J. Martens

The statistical information and cost data used in this report has been made available by NICKDATA INC. Since 1982, NICKDATA INC. of Toronto, Canada, has produced an annual comprehensive nickel industry cost study. Up to date information on 22 mines, 21 smelters, and 16 nickel refineries representing 30 nickel production operations in 17 countries are included in the computerized cost analysis. The report is compiled from information obtained through regular annual visits to major nickel operations and continuous monitoring of information on all nickel producers. The 1984 report which was completed this summer, reveals drastic changes in the nickel industry cost structures.

Jan 1, 1984

By Omar A. Muhtadi

Brohm Mining Corporation, in conjunction with Geobiotics, Inc. has nearly completed a pilot heap biooxidation test on sulfidic ore from the Gilt Edge Mine near Rapid City, South Dakota. Some results from the pilot testing have shown the correlation between the extent of biooxidation and the increase in cyanide gold recovery seen in the laboratory. Bench scale testing showed approximately a 1: 1 correspondence between percent biooxidation and percentage increase in gold recovery. The economics of large scale biooxidation were also evaluated in terms of increased gold recovery versus the time and cost of biooxidation. In the pilot test, the rate of biooxidation became limited by the acid water neutralization system. Later in the test, measures were taken to overcome this problem. Results from bench scale column bioleach testing showed that the Gilt Edge sulfide ore is quite amenable to biooxidation with a substantial increase in gold recovery with just partial biooxidation. Direct cyanide gold recovery of 51 % on ore crushed to -3/8" was enhanced to 82-85% after oxidation of37% of the sulfide as measured by iron. Laboratory experiments also showed that the slow rate of biooxidation of this ore could be accelerated by removal of metal sulfate build up from the leach liquor. The combination of these normally non-toxic metals became inhibitory to biooxidation if not removed by the neutralization circuit.

Jan 1, 1995

By Klaus Grebe

Recent investigations by Mannesmann Research have shown that disintegration of sinter with widely varying quality levels is subject to a much more complex set of influences than was previously assumed. It was confirmed that disintegration at temperatures between 300 and 600 °C is triggered by the degradation of hematite. The specific tendency of hematite to disintegrate is, however, not constant: sinters containing the same amount of hematite can show widely differing disintegration tendencies depending upon structural homogeneity, porosity and gangue quantity. Especially sinters with heterogeneous structures transmit stress to the hematite phase and this favours disintegration. Another factor is the brittleness of the glassy silicate phase, which can be influenced even by small modifications of minor gangue constituents.

Jan 1, 1981

By Gerd L. Klinkenborg

Throughout the history of the development of mechanical conveyor systems, it has always been an established condition that loads are received at one end of a single-belt conveyor and discharged at the other end, in a point-to-point, manner. In systems designed for the continuous transport of granular materials, vertical or horizontal changes in; direction have always necessitated two or mope single-belt conveyor units, with a corresponding number of motors, assemblies and attendant mechanical and human or electronic controls. Besides these high-cost factors, every change in the system's direction also calls for a transfer point that involves a drop-back of the material from one level to another with some loss of the material and, in many cases, unwanted additional granulation. Where changes in the location of the discharge point are wanted, the conventional single-belt conveyor must either be replaced by a shorter or longer unit or additional units purchased and installed, or existing units rearranged. This can take days or weeks, and involve special expenditures as well as loss of valuable production time.

Jan 1, 1962

By D. R. Schmitt, B. L. Jensen, T. J. Ahrens, C. L. Smither

The in situ elastic moduli of rock are measured holographically by a borehole instrument in marble and oil shale. A point force induced displacement field is recorded with double expo- sure holography. Data consists of a fringe pat- tern on the viewed hologram. The elastic moduli are determined by modelling of the fringe pattern. Only Young's inodulus is fairly constrained by the present data reduction. For an applied force of 520 [ ] 50 Newtons, a marble was found to have a Young's modulus of 56 [ ] 8 GPa, near an ultrasonically determined value of 48 [ ] 6 GPa. In an oil shale, an applied force of [ ]

Jan 1, 1986

By Graham Jones

During 1982 Ash Grove Cement Company contracted with Wagester, Walker, Thornton & Company to convert a Calcimatic rotating hearth kiln at its Portland, Oregon lime plant from gas/oil to coal firing. Increasing costs of natural gas and No. 6 fuel oil made this conversion mandatory if the plant was to remain competitive. Unique features of this project are 1) the distributors of pulverized coal to eighteen small burners around the inner and outer perimeters of the doughnut-shaped kiln, and 2) the attrition-dryer-pulverizer mill. Ash Grove, a century-old lime and cement producer headquartered in Overland Park, Kansas (Kansas City area), looked at various schemes for multiple burner firing before employing Wagester, Walker, Thornton & Company. W.W.T. of Pitts- burgh, Pennsylvania was formed in 1980 by acquiring the Solid Fuels Division of the Pullman Swindell Corporation. This division had been active in developing solid fuel firing for brick tunnel kilns, principally in the Southeast. They continue to supply such systems firing wood waste as well as coal to the brick industry and have also converted two Calcimatic lime kilns for Dixie Lime, Sumterville, Florida, a fluid bed calciner for Texas Gulf in Aurora, North Carolina, and a chrome concentrate kiln for Diamond Chemicals at Castle Hayne, North Carolina. Testing and a proposal have been made for INMETCO, Elwood City, Pennsylvania, on an annular hearth furnace for direct reduction of iron ore to metallic iron.

Jan 1, 1984

By E. Ben-Awuah, H. Askari-Nasab, N. Al Habib

Open pit mines are getting deeper with time and transportation expenses are increasing because of the increasing haulage distance. In-pit crushing and conveying (IPCC) is getting popular in deeper open pit mines as a suitable alternative to truck haulage because it offers a lower operating cost due to shorter haulage distance and less truck requirement. Semi-mobile in-pit crusher, currently the most popular IPCC system, is relocated every two to five years and the short-term plan needs to be updated accordingly. Short-term planning with IPCC is an area of research that has not been explored extensively yet and hardly any model can generate short-term extraction sequence considering an IPCC in place. This research work proposes a mixed integer programming model to generate short-term production plan within a time horizon of 12 months. The objective of the model is to optimally allocate shovels to minimize cost of material handling and maximize revenue subject to meeting plant requirement, maximum allowable tonnage variation and IPCC location constraints to achieve production and NPV targets set by strategic plan. The proposed model has been implemented in a hypothetical case study for verification. The comparison of results between scenarios with and without IPCC is expected to justify the use of IPCC in large open pit mines from a short to medium term perspective. A semi-mobile IPCC system with one relocation is considered in the case study.

Feb 1, 2023

By R. A. Matuszak

Historically most mine management teams have been forced to operate in a more or less subjective manner. The objectives of mine management are simple and clear. Like other operational managements, mine management teams have the traditional well defined goals of improving efficiency and production while decreasing costs. Unlike other operational managements however, mining teams deal regularly with a vast assortment of uncertainties caused by: - Key production tools being mobile and widely dispersed, and - Non-uniform mining conditions At best in most operations these conditions cause obstacles to productivity and at the same time cause long delay in managment awareness of the obstacles. Planning with delayed feedback of information about necessary deviations is incomplete planning. For these reasons increased operational efficiency remains a constant though somewhat elusive goal.

Jan 1, 1985

By C. Bazin

The fundamental error associated to the sampling of heterogeneous ore particles is unavoidable and can only be minimized by an adequate selection of the sample mass and/or size reduction of the sample before division into sub samples for testing or assaying. The preparation of ore batches to carry out the mineral processing evaluation of an ore is a sampling process. The fundamental error associated with the division of the ore into batches is responsible for the differences in the composition of the batches. This paper attempts by various means to assess the reproducibility of the gold content of test batches prepared from a gold ore sample. The results of the investigation shows that for fine gold grain sizes the variability in the composition of the batches is less than that predicted by Gy?s formula and that the gold grain size is a strategic information in the assessment of the gold content variability of test batches.

Feb 23, 2014

By David A. Zegeer

It's a pleasure to be here, and an honor to be invited to address this distinguished group of professionals. Today, I'd like to begin with an overview of progress in coal mine safety and health. I'll discuss some current areas of concern. And I'll make some suggestions as to where we may be headed in the future. This year marks the coal industry's 15th anniversary under the Coal Mine Safety and Health Act, which took effect in 1970. We have come a long way in those 15 years. As a coal mining man from way back, I remember the era when the Coal Mine Safety and Health Act first was passed. Some of you may remember it, too. At that time, the safety and health of coal miners was in the public eye even more than it is at present. One reason was a mine explosion that killed 78 miners when it occurred in a large underground coal mine in November 1968. That disaster raised tremendous public concern about protecting the safety of miners.

Jan 1, 1985

By A. T. Yu

Technology and economies of scale have, in the past decade, brought about the emergence of giant vessels. Meanwhile, to answer the need for rapid dispatch, as a means of combating the proportionately far greater demurrage charges, shiploading and unloading speeds have soared (Ref. 1, 2, 3). As the loading and unloading rates have dramatically increased, so has the cloud of dust grown in unbearable proportions. It not only has threatened to be a real menace to machinery and men, but in certain instances has also seriously jeopardized fish and marine life (Ref. 4). In an era when ecology is king, dust in shiploading and unloading can no longer be shrugged off as a mere public nuisance, and its control is now duly recognized as of grave concern to all. Even if public outcry were not a problem, from the operator's own parochial point of view, dust can adversely affect productivity and the well-being of the operating personnel. Without adequate control, it can also result in costly equipment maintenance, particularly when the dust is micronic in size, and abrasive. The Hierarchy of Control Techniques Given the great fortune of not yet having to deal with gas and odors, in the jargon of pollution control, our problem is confined to having to control "particulates" only. To deal with "particulates", the myriad of dust control techniques can be utterly confusing to those who are not entirely well versed in the methodology. Our analysis of what is available to date results in the following hierarchy of logical preferences: 1. Prevention 2. Removal 3. Suppression 4. Containment 5. Dilution Since it deals with the root cause, prevention always outranks the cure. Once the dust is generated, removal nips it in the bud. Only when dust removal is

Jan 1, 1972

By Victor M. Mercado, Jay B. Shah

Spalding DeDecker Associates, Inc. (SDA) designed a tunnel project that fulfilled the Sustainability Objectives of Social Equity, Environment, and Economics. The project translated the principles of Sustainable Development into actions that lessened the impacts of construction on environment, lives of residents, businesses, traffic, and other social systems (i.e., shopping, recreational, and educational). The project involved the construction of a 16,108 feet of 84 inch diameter sanitary sewer interceptor by tunneling 40 feet beneath the ground surface through difficult geological and hydrogeological settings. An effective public information and stakeholders relationship program was developed to achieve the stated objectives of sustainability.

Jan 1, 2003

By Kenneth J. Miller

A novel two-stage froth flotation process to remove pyritic sulfur from fine- size coal is described. The process consists of a first-stage, standard coal flotation step in which high-ash refuse and some of the pyrite are removed as tailings. The first-stage clean coal froth concentrate is then repulped in fresh water, and a coal depressant, a pyrite collector, and a frother are added to float the remaining pyritic material. Laboratory and pilot plant flotation results with coals from the Lower Freeport and Pittsburgh beds are given. The pilot plant test results show that up to 80 percent pyritic sulfur reduction was achieved with the Lower Freeport bed coal and up to 50 percent with the Pittsburgh bed coal. Laboratory and pilot plant results were in excellent agreement, indicating that the process is a viable means of removing much of the sulfur from some coals.

Jan 1, 1974

By Key Rosebrook, Jennifer Laggan, Ashley Rivera

Significant quantities of waste rock at abandoned uranium mine (AUM) sites in the western United States require removal from steep slopes exceeding 45 degrees in remote locations. This prevents the use of traditional excavation equipment and poses significant challenges for safe, effective material removal. A pilot study was conducted using a spider excavator to demonstrate the feasibility of removing waste rock and transporting it to areas where conventional equipment could be employed. The spider excavator was evaluated for its effectiveness in excavation, material movement and control, container usage, dust mitigation, and ensuring human health and environmental safety. The study established constructability and engineering parameters for implementing spider excavators in these challenging environments. Key outcomes include the preservation of existing vegetation, improved waste movement control, and enhanced safety measures for workers, nearby residents, and the environment.

Feb 1, 2025

By Roberto Pimentel de Souza

Since 1976 CVRD is carrying out tests to develop a type of pellet made with organic binder. One binder that showed good possibility to be used in industrial plants is Peridur. An extensive framework of tests was run in CVRD's pilot plant. The results are presented in this paper. Finally, the decision was taken to carry out an industrial production of 50.000 t of pellets. It was scheduled for March '81. The results are shown in this pager. It was not observed any detrimental effect of the peridur neither in the process nor in the product quality.

Jan 1, 1981

By Shawn T. Sorrell

Phillips Coal Company (PCC) submitted the first surface mine permit application under the Office of Surface &lining approved regulatory program of the State of Louisiana. This application for the Oxbow Lignite Surface Mine which is located approximately 64 kilometers (40 miles) southeast of Shreveport, Louisiana was submitted in March 1981. The State of Louisiana Office of Conservation, Surface Mining Division, assigned this application number LSM-1, indicating it is the first one submitted in Louisiana history. The permit area for the Oxbow Mine encompasses 6,251 hectares (15,627 acres). Of this total permit area, 5,862 hectares (14,656 acres) were classified by soil type as prime farmland by the U.S. Soil Conservation Service (SCS). Prime farmland acreage in the permit area became a major central issue in our early planning stages and throughout the permitting process of the Oxbow Mine, due to the magnitude of acreage involved.

Jan 1, 1982

By J. C. Agarwal

A significant portion of the, coal mined by U. S. Steel is beneficiated to upgrade the quality of the resultant coke to meet blast-furnace requirements. Primarily because of degradation from modern mechanized mining methods, a considerable quantity of the coal to be beneficiated is in the 1/4-inch by 100-mesh size range. In the cleaning plants, this coal is usually cleaned on concentrating tables and then mechanically dewatered in solid-bowl centrifuges to 9 to 14 percent water. At some plants, to further decrease the amount of water shipped with coal, and to improve the coking characteristics of the coal at its destination, mechanical dewatering is followed by thermal drying. At U. S. Steel's-Alpheus preparation plant at Gary, West Virginia, approximately 50 percent of the total coal produced is in this fine size range, and two fluidized-bed dryers are used for the thermal drying step. The two fluidized-bed dryers are 14 feet in diameter and were designed by the Dorr-Oliver Company. Although the original design called for a rate of drying equivalent to 37 tons, of moisture per hour, presently they are removing twice that amount. This paper describes, the major problems encountered' in operating these dryers at the present, high capacities and how they were overcome.

Jan 1, 1963

By William Gleason

"What will the mine of the future look like? Will it resemble the current operations that supply the world with the products it needs to function, or will it be something totally different? How will the demands from the communities that are most affected by mining operations shape the mine of the future? How will technology and innovation be used to help miners reach deposits that are getting harder to access, and what are the dangers of this new world? Who will work at the mine of the future, and what will that work look like?These are questions that do not yet have definitive answers, but they are questions that need to be asked for the mining industry to move into a future that is as filled with uncertainty and challenge as it is with promise and opportunity.On Feb. 16, the 2015 SME Annual Conference and Expo and the 117th CMA National Western Mining Association conference began with a keynote address, "The mine of the future: Forecasting opportunities and challenges for the global mining industry." Panelists from five sectors of the mining industry participated in the session, which was followed by the conference and expo, that in large part, were also trying to answer the question of what the mine of the future will look like.In coming months, Mining Engineering will continue the discussions and answer some of the questions submitted by members of the 2,000-person audience during the keynote address in a monthly feature called, "Predicting the Mine of the Future," and in Thought Leaders Podcasts with the panelists and other industry experts."

Jan 1, 2014

By Alain A. Sonntag

The MBS Solvent Extraction System utilises a unique design of mixer- settler having very high capacity per unit area and great flexibility. The development of the mixer-settler is traced through its various stages wherein the independence of mixing and pumping, reduction in settler area requirements and simplicity of plant layout were achieved. The laboratory, pilot plant and full scale tests contributing to the development of the machine are described. The existing KREBS SX plants in Europe and Africa are described as well as the plants presently under design. Results of recent testwork are also given.

Jan 1, 1981