Search Documents

By C. A. Rowland

When studying the feasibility of using autogenous or semi-autogenous grinding, operating and engineering companies frequently request assistance from the mill manufacturers in three areas - 1. Recommendations for studying the suitability of autogenous or semi-autogenous grinding for the specific ore. 2. Mill sizing, to accomplish required grind. 3. Recommendations on mill design and operation. Rod mills and ball mills are selected by the use of bench scale standard grindability tests and established calculation procedures, of which the most frequently used are the Bond Grindability tests and the Bond Work Index equation(1). The accuracy of these have been reviewed by C. A. Rowland in his papers, showing the correlation of work indices calculated from plant operating data and laboratory grindability tests(2)(3). The selection of autogenous and semi-autogenous primary mills has not reached the stage where mill size selection can be made from bench scale tests. Considerably more extensive testing will be necessary than required for selecting rod mills and ball mills.

Jan 1, 1974

By Jr. Foot

EIMCO Process Equipment Company has introduced the new SmartCell series of conventional flotation cells. The flagship of this new development is the 5000 ft3 cell that is the largest available in industry. This new series of cells includes a cylindrical tank design, a conical draft tube and froth crowder. Optional air control, wash water addition and embedded expert control are available. A discussion of the design parameters, energy efficiency, testing, and commercial plant results are presented.

Jan 1, 1997

By Chao Zhang, Wenhao Xia, Jianxin Fu, Ling Yu, Weidong Song, Yang Li

Sanshandao Gold Mine is the only undersea metal mine in China. To deal with the collapse and pumping of stopes and roadways caused by complex ore-rock occurrence conditions, the mine conducts filling and sealing of some areas, and the remaining ore reserves will be mined after treatment. Therefore, it is urgent to evaluate the stability of rock masses, fault fracture zones, and aquicludes during the secondary mining process. In this study, displacement and microseismic methods are employed to monitor rock deformation and fractures. Additionally, FLAC3D was used to simulate the process of secondary mining, reproducing the evolution of stress fields, displacement fields, seepage fields, and plastic zones at different mining stages. The combination of numerical simulation and on-site monitoring verification demonstrates that the deformation of surrounding rock presents a rapid growth at the initial stage of mining, followed by a gradual decrease in the growth rate, and finally tends to stabilize; the fracture zone area at the 151–159 exploration line on the − 320 m level (near the 7# and 8# stopes) exhibits poor stability, and monitoring measures should be strengthened; the deformation value of the aquiclude is less than the deformation value of I protection level in the Code for Design, the impact of secondary mining on the aquiclude is limited; fault and fracture zone deteriorate rock mass stability, and their impact is related to their spatial locations. Hanging wall fault has a more significant impact on the settlement of the aquiclude, while the footwall fracture zone has a greater impact on the development of the plastic zone.

Feb 21, 2024

The Kinross DeLamar Mine has been operated for more than 17 years producing precious metals dore' from ores, principally silver bearing with associated gold co-products. In late 1995 a new orebody was commissioned, the Stone Cabin orebody, and the site began a phased shift from silver dominance to gold dominance in terms of precious metals revenue. The Knelson Concentrator was selected to remove gold from a portion of the cyclone underflow stream in the grinding circuit. This paper describes the development of the flow sheet, specific mineralogical impacts on Knelson product and downstream materials, and impacts on mine/mill grade reconciliation.

Jan 1, 1997

By P. R. Thomas

This paper addresses the relative long-term cost and resource position of new and existing ferrochromium production in selected Market Economy Countries (MEC'S). The market impact of new ferrochromium production in nations such as India and the Philippines and the continuing change in international trading patterns are also evaluated. This paper draws upon the data and analyses of a recent Bureau of Mines, Department of Interior, Minerals Availability Program appraisal that evaluated the cost and availability of chromite and ferrochromium production from the demonstrated resources of 80 producing or potential mining operations in 10 market economy countries.

Jan 1, 1984

By F. Milton Lewis

Several alternatives are available for treating lover grade gold ores averaging 0.04 to 0.10 ounce per ton. These include heap, vat and agitation leaching and may involve conventional zinc precipitation or carbon adsorption-electrowinning systems. Each of these processes have their inherent economic and operating advantages and disadvantages and the selection of the optimum method for a given gold ore is solely based on economic evaluation of the applicable processes. In this paper an effort is made to provide engineering feasibility estimates for the above processes under varying operational conditions such as ore grade and price of gold.

Jan 1, 1974

By Frank Cook

As in other areas of the country, surface coal mine productivity in the Central Coal Province--primarily Illinois, Indiana, and west Kentucky--has declined steadily since 1969 (figure 1). Productivity, as measured in tons of clean coal produced per man-shift, dropped 35 percent during the period 1969-1975. Unwelcome at any time, this phenomenon is particularly untimely now, when increased coal production is a national goal. The U.S. Bureau of Mines has been working with the coal industry to develop new operating methods and equipment to enable increased productivity and improved reclamation performance in surface coal mining. Several projects have involved identification and evaluation of existing overburden handling and reclamation practices, and development of means to improve operational procedures. Some results of one of those projects, as they apply to the Central Coal Province, are summarized in this paper.

Jan 1, 1977

By A. Juganda, F. WILSON, G.E. BOGIN, H. PINHEIRO, N. SANDOVAL, J.F. BRUNE

To evaluate methane explosion hazards in underground longwall coal mines, researchers at the Colorado School of Mines developed a computational fluid dynamics (CFD) model along with a 1/40th-scale, optically accessible, physical model of a longwall mining section. In this project, CFD models assisted in the design of the physical model to ensure specifications were met to accurately represent the scaling physics as well as to assist in narrowing the experimental matrix and identifying key locations for sensor placement to measure velocity, pressure and gas concentrations. This research will help develop strategies for methane monitoring to prevent methane ignitions and explosions in longwall coal operations.

Dec 1, 2022

By C. H. Stephenson, Z. White

This paper presents the design approach case study for incorporating a Technogrid® conveyance End-of-wind arresting system within the new South32 Hermosa headframe. Focus is placed on energy absorption requirements, structural integration, and mounting details tailored to the geometry and operational constraints of the headframe. Key considerations include arresting forces, load path continuity, and connection design to ensure reliability and maintainability. The paper also discusses coordination with other headframe systems and the iterative design process used to meet safety standards and client objectives.

Feb 22, 2026

By V. G. Medina

The 15 000 t/d La Coipa mine initiated operation in July of 1991. The complex consists of a conventional, open-pit mining operation and a mill employing cyanide leaching with Merrill-Crowe gold and silver recovery. The process plant includes a primary crushing circuit, a 15,000 t (live) covered stockpile, a semi-autogenous mill/ball mill/crusher or SABC grinding circuit, a leach circuit, a belt filtration/washing circuit, a zinc precipitation circuit and a "dry" tailing disposal system. The process plant is described in detail with major design considerations used in the selection of the processes and equipment. The unique methodology employed in the disposal of the filtered tailings is also described.

Jan 1, 1992

By Alireza Kamrani, Yashar Pourrahimian, Hooman Askari-Nasab

In-pit crushing and conveying (IPCC) is an option to decrease the enormous operating costs that a truck shovel can introduce in an open-pit mine. Finding the best locations for the IPCC over the mine life will impose a new set of requirements for the mine planning. Through a two-step mathematical programming model alongside the road network, this method finds the optimal in-pit crusher locations and relocation times first and then optimizes the long-term mine schedule. The model is verified by a real mine. The results show that the truck travel time could be reduced by 500% and the discounted cash flow increased by 8% with an optimized schedule considering the crusher placement.

Jun 25, 2023

By D. J. Turk

Faced with decreasing production from the gold heap leach operation, Robinson implemented a drilling and blasting program on the leach pads in 1993. This program offset some of the negative effects of low ore permeability and short circuiting of leach solution that resulted in lower than optimum recoveries. The drilling and blasting program created new solution flow paths and increased gold recovery. Production and pulp assays at depth intervals, prior to and following drilling and blasting, reveal the degree of short circuiting and benefits of the program.

Jan 1, 1995

By Donivan L. Gordon

One of the several problems facing society today is that of disposing of its solid waste. Each year this nation spends approximately 4.5 billion dollars to collect, transport and dispose of some 360 million tons of domestic and industrial solid waste. Although considerable sums of time and money have been spent in researching various techniques for solid waste disposal, it is presently agreed that sanitary landfilling represents the most economic and universally adaptable solution to the problem of solid waste disposal. However, regardless of the factors favoring sanitary landfilling as the waste disposal method of choice, it should be recognized as carrying with it a potential for the degradation of ground- and surfacewater resources. Through an interdisciplinary effort regulations were promulgated during 1971 in the State of Iowa to govern sanitary disposal projects. Consistent with a set of rationales developed to preserve environmental quality, these regulations set forth hydrologic and geologic standards designed to protect Iowa's water resources. Minimum requirements have been outlined in the regulations through which the natural favorability of potential landfill sites may be evaluated. Natural favorability is primarily defined in terms of the hydrologic and geologic relationships between a proposed landfill site and those in the locality of the site. The regulations specify that leakage from a landfill to a subcropping aquifer must be less than 0.04 cu ft/day/sq ft at the base of the landfill. This factor is offered to quantify the maximum allowable leakage for all sites in unconsolidated sequences underlain by subcropping bedrock aquifers, Based on groundwater research in Iowa, the assumption is made that 50 feet of till will be sufficient to inhibit the downward flow of liquids from a landfill into bedrock aquifers. This assumes a difference of no greater than 40 feet in hydrostatic head between the water table in the unconsolidated sequence and that in the bedrock aquifer. Owing to the fact that bedrock aquifers in many areas of the state are mantled by less than 50 feet of till the regulations provide for site modification, through engineering, to meet the specified leakage standard, In such instances the leakage factor is evaluated by means of the generalized Darcy's Law Q = PIA where:

Jan 1, 1974

Small-scale flotation tests have been conducted to examine the effect of froth stability on the column flotation of finely pulverized coal. The results of this study demonstrate that the upgrading of coal in a column flotation cell can be significantly improved when froth stability is properly controlled through the manipulation of appropriate operating variables. Several important correlations have been established from the test data. These relationships should prove useful for the design and ore ration of column flotation cells for fine coal processing.

Jan 1, 1991

By Lauren M. Roberts, Ralph R. Sacrison

Pipeline or borehole free-fall transfer of material has long been done in support of underground mining. This paper addresses some characteristics and design elements in selecting systems suitable to the transferred media and the mine requirements. Though aspects of overall systems are discussed, principal attention is directed to the slickline/dropline/transfer line and the discharge diverter/rockbox/energy dissipator/boot. These terms are common to these systems, often used interchangeably, and will be used as appropriate to the material, equipment and construction. Following several design sections, fabrication and construction, and system operating and maintenance procedures are discussed.

Feb 1, 2025

By Robert L. Frantz

The U.S. Bureau of Mines (USBM) established on August 15, 1983, a Generic Mineral f Technology Center (GTC) for Respirable Dust within the Mining and Mineral Resources Research Institutes (MRIs) at The Pennsylvania State University (PSU) and West Virginia University (WW) in association with participating MRIs at Massachusetts Institute of Technology (MIT) and the University of Minnesota (UMN). The primary goal of the Center is to reduce the incidence and severity of respirable dust disease through researching and advancing the fundamental under- standing of all aspects of respirable dust associated with mining and milling and the interaction of dust and lungs. Other Center activities include the training of engineers and scientists, graduate students and undergraduate students through their respective institutions, and the technology transfer to the industry. The Center also serves as the reference center for publications in the respirable dust area.

Jan 1, 1986

By T. Panhorst

Evaluation of through-deck blasthole sample reliability at the Lone Tree gold mine revealed a non-systematic bias in the sampling system. Ore is primarily hosted within the Powerline fault zone. Clay gouge, present in the fault zone and typically enriched in gold content, forms agglomerates during blasthole drilling leading to a segregation error during sampling. Replicated samples split from blasthole cuttings piles show through-deck samples to be either significantly enriched or depleted by 1.5 standard deviations or more from the mean gold content of their respective cuttings pile quality of through-deck samples correlates strongly with quantity of clay present.

Jan 1, 1999

By N. Nemeth

The filter is an apparatus designed to hold the filter medium. At such a medium takes place the entire liquid-solid or gas-solid separation process. Hence, the medium is really the essence of filtration. Yet, the medium, an originally clean porous substance with trapped solids in it, is perhaps the most neglected part of filtration research. Basically three problems prevail at the medium: 1) Penetration of solids and their blinding of the medium and the influence of such blinding on the resistance to flow. ii) The behavior of the medium in long term repetitive filtration. iii) The filter effect phenomenon whereby the flow rate on filtering an apparently clear liquid through a medium decreases with time. This study undertakes to investigate these fundamental processes.

Jan 1, 1968

By CHENCHEN SUN, GUOPING LUO, GUOCHENG ZHANG

Preparation of briquettes by adding CaF2 reagent into the Australian iron ore powder. The structure and morphology of iron ore briquettes during various reduction stages (i.e., Fe2O3→Fe3O4, Fe3O4→FeO, and FeO→Fe) were observed via an ore microscope and scanning electron microscopy. The results showed that CaF2 reacted with SiO2 to form CaO and SiF4 gas during the roasting process. The reduction swelling index decreased from 12.36 to 8.83% when the CaF2 content in the briquettes increased due to CaF2-mediated refinement of the hematite grains during the first stage of the reduction process. Lattice distortion resulting from the presence of Ca2+ in the FeO lattice during the second stage of the reduction process, coupled with an increase in the porosity of the iron ore briquettes and the formation of a low-melting-point slag phase, promoted the anisotropic growth of FeO lamellar crystals, which resulted in an increase in the reduction swelling index from 4.27 to 7.36%. During the third stage of the reduction process, the growth of iron whiskers was promoted by wüstite (FeO) lattice distortion caused by a solid solution of Ca2+ in the FeO lattice; the reduction swelling index increased from 15.61 to 24.72%, resulting in the catastrophic swelling of the iron ore briquettes.

May 27, 2021

By A. Bergmann

Location The Meggen Mine and the concentrator plant of the "Sachtleben Bergbau G.m.b.H." are located in the southern part of the Ruhr-district of the Federal Republic of Germany. The mine has been in operation for more than 100 years, but the concentrator described in this paper was built in 1962 and started up in January 1963. Goelogy and Mining The Meggen ore-body is of sedimentary origin and occurs in a zone of limestones, graywacke and shales of Devonion age. The average thickness of the deposit is 3 meters and, due to an intense folding of the area, the mineralized zone dips very steeply at 800 toward the north. The ore consists of 85 percent of sulfides and 15 percent gangue that mainly contains silicates from the host rocks. The principal ore minerals are pyrite (67 percent), sphalerite (16 percent) and galena (2 percent) with minor amounts of marcasite and only traces of chalcopyrite. As shown in Fig. 1, the sphalerite and galena are very finely disseminated in the massive pyrite of the Meggen ore, and a very fine grinding combined with a special flotation technique are required to liberate the valuable sulfides and to produce separate concentrates of lead, zinc and pyrite. Mining is performed by the sub-level stoping method and employs trackless equipment. Present operations provide ore from the 600 meter level. Annual ore production is 870,000 metric tons.

Jan 1, 1972