Search Documents

By M. N. Plis

This report describes the initial results of long-range research on bit life conducted by the Bureau of Mines. Three commercial bit designs -a round-nose radial, 60° conical, and 90° conical with tungsten carbide (WC) inserts -and five experimental bits were tested. Four of the experimental bits were radial designs using polycrystalline diamond compact (PDC) inserts. The fifth was a 90° conical with an oversize WC insert. Bits were worn on a high-silica sandstone typical of coal mine roofs. The bits were mounted on a 34-in-diam drum section that provided a bit speed of 565 ft/min. Cutting forces were measured on a modified vertical slotter using a three-axis force dynamometer and recorded on an FM magnetic tape recorder. Changes in cutting forces, bit weight, and airborne dust due to gradual abrasive wear and catastrophic insert failure are presented. Tabulated and graphed data, photographs of the progression of bit wear, and selected qualitative visual and auditory observations of the bits taken throughout the experiment are found in the appendixes. The results show that bit life ranged from approximately 16,000 ft for the WC round-nose radial bit to over 125,000 ft for a PDC round-nose radial. Performance, in terms of bit life, cutting forces, wear rate, frictional sparking, machine vibration, and noise was in general best with the PDC bits, followed by the rotating WC bits, with the nonrotating WC bits (round-nose radial and locked 60° conical) being the worst. The results show variations in the included tip angles of new conical bits have an insignificant influence on bit performance when the effects are averaged over the life of the bit. In addition, new bits were generally found to entrain more primary respirable dust for a given cutting distance than worn-out bits. It is hypothesized that this is due to the difference in frictional behavior between new and worn bits. The results from these tests are being used in the Bureau's cutting system model (CSM).

Jan 1, 1988

By T. P. Meloy

A methodology is presented for the spreadsheet solution of processing networks performing separations with the methodology developed here a spreadsheet grid is used to represent networks with and without recycle loops. In this manner, network solutions are numerically approximated by spreadsheet grid solutions. The methodology was used to explore the ramification networks developed by the Chinese for tungsten and molybdenum processing. Non-linear stage transfer functions for two-component sharp separations can be used.

Jan 1, 1994

Asgco’s design of the Arrowhead Ceramic Lagging provides solutions to problems experienced with conveyor belt slippage around the drive pulley and severe wear problems on snub and bend pulleys. Asgco has developed a range of pulley lagging from ceramic, drive rubber and non-drive rubber lagging that is available in abrasion-resistant SBR and MSHA grade rubber for conveyor pulleys from slow belts all the way through to high-speed, high load belts. There is a growing need for a maintenance-free and reliable pulley lagging to ensure conveyor belts run to their highest efficiency.

Jan 1, 2006

By D. D. Munro

Finsch Mine is a Kimberlite diamond mine located at Lime Acres in the Northern Cape of South Africa. The mine was founded in 1961 and started surface-mining in 1964. Underground production commenced in 1990 using a Modified Blast Hole Open Stoping method for the mining of Blocks 1,2 and 3. Block 4 is currently being mined as a Block Cave. The process of identifying and optimizing a mining method to mine the Block 5 ore body started in 1991 and in 2006 Inclined Caving was identified as being a technically feasible method. This report aims to document the process employed in developing this method by the Block 5 Pre-Feasibility Team as well as discussing the technical challenges encountered during this process.

Jan 1, 2010

By Ali Jaberi Zamharir, Abolfazl Shoghian‐Alanaghi, Hossein Aghajani, Arvin Taghizadeh Tabrizi

In this study, the leaching rate of molybdenite concentrate was evaluated in sulfuric medium, and the influence of the diverse oxidants including hydrogen peroxide, manganese oxide, copper sulfate on the leaching rate was studied. Also, the effect of the addition of the ethylene glycol to the hydrogen peroxide was studied and results showed that with the addition of ethylene glycol, the leaching rate is increased 55% from 41% up to 80.3%. The optimum condition is achieved as 0.7 M of H2SO4, 4.4 M of H2O2, and 3.5 M of EG at 30 °C within 4 h of leaching time and 500 rpm. Also, inserting the oxygen with the pressure of 6 bar to the leaching autoclave, the leaching rate is increased more up to 86.4%. Finally, the leaching process was studied kinetically and the determined mode of controlling factor was specified based on the activation energy which equals 46.252 kJ/mole indicating the chemical reaction mode.

Jun 5, 2022

By Calvin J. Konya

Overloaded blastholes and insufficient stemming are major factors in flyrock accidents at surface metal and non-metal mines, Accurate measurement of blasthole depth, stemming height, and water depth would reduce the overload and the probability of blow-out, flyrock, excessive ground vibration, and airblast. Problems result because current measuring systems are inaccurate and often difficult to used A literature survey determined measurement techniques and blasting parameters prior to 1970. Similar data were gathered for current practices in 11 iron mines, 30 copper mines, and 92 quarries. Most operations used a cloth tape to measure borehole depth and stemming height; approximately 10% of the operations had dry blastholes. Alternate measurement techniques were evaluated and discussed. Candidate measuring techniques with best potential for improvement over the present weighted tape method are disposable tapes or string chains, automated readout tapes, modified sludge level indicators and acoustic resonance methods.

Jan 1, 1981

The Sixty-Second Regular Meeting of the Rocky Mountain Coal Mining Institute convening at the Stanley Hotel in Estes Park, Colorado, was declared in session at 10 a.m. by Past President Oren F. Bridwell, Secretary, Northern Colorado Coals, Inc, Denver, Colorado. Mr. Bridwell thanked the Joy Manufacturing Company fer the very fine party of the previous evening. He also paid tribute to a very fine Committee - the Program Committee: O. F. Lewis, Chairman, Oren Bridwell, Edward G. Fox, Glen E. Sorensen, Joseph E. Ward, R. R. Williams, Jr., and John Peperakis. Mr. Bridwell then introduced George A. Nugent, Vice President and General Manager, Big Horn Coal Company, Sheridan, Wyoming, as follows: "It is my privilege and duty to call this 62nd Regular Meeting of the Rocky Mountain Coal Mining Institute to order and to extend to you all a cordial welcome.

Jan 1, 1966

By Berglin IK

Since 1962, ferro alloy production in Australia has been concentrated at Bell Bay, Tasmania with a major expansion occurring in 1976. This concentration was based originally on the perceived requirements of the expanding Australian steel industry, but recent stagnation within this industry has seen Temco become progressively more export oriented.In 1984, approval was given for a $47 million uprating of facilities which will allow for the introduction of the latest technology to ensure high quality, low cost production in a highly competitive export market.

Jan 1, 1985

By R Schmitt, Y Ghorbani, I McElroy, N J. Bolin, M Parian

Aitik is a large copper porphyry type deposit located in northern Sweden, currently exploited at an annual rate of approximately 45 Mt. The ore’s exceptionally low head grade of 0.25 per cent Cu and varying degrees of hardness across the entire deposit pose challenges to the two fully autogenous grinding lines, each of which comprises a primary autogenous mill in series with a pebble mill. The variability in ore grindability frequently leads to fluctuations in mill throughput. Within the framework of a geometallurgical approach, the present study investigated the relationships between ore grindability and modal mineralogy. For this purpose, drill core samples from different lithologies were subjected to Boliden AB’s in-house grindability tests. This fully autogenous laboratory-scale test generates a grindability index mainly related to abrasion breakage, which is a significant breakage mechanism within autogenous mills. The test results suggested divergent degrees of grindability within and across the selected rock types. A combination of scanning electron microscopy, X-ray powder diffraction, and X-ray fluorescence analyses was performed for the grinding products and bulk mineral samples. The resulting mineralogical and elemental properties were subsequently correlated to the parameters from the grindability tests. It was shown that the main mineral phases, such as plagioclase, quartz, and micas, correlate well with the grindability indices. Similar correlations were found regarding the sample’s chemical composition, attributable to the main mineral phases. A further inverse correlation was established between the sample’s calculated average Mohs hardness and the grindability indices. Moreover, mineral liberation information provided by scanning electron microscopy was associated with the parameters mentioned earlier. The identified relationships between grindability, modal mineralogy, and element grades may help Boliden develop a predictive throughput model for Aitik based on the mine’s block model.

Aug 24, 2022

By Hector O. Romero, Paulo C. Fernández A, Christian Rees Prado, Claudio C. Gajardo

In open-pit mining, estimating post blasting displacement and spillage accurately is essential to guarantee operational efficiency, ensure alignment with production plans and their associated key performance indicators. The absence of predictive modeling tools on blasting operations results in several critical challenges, including operational reworks due to deviations in material displacement, significant discrepancies between mine and plant (ore grade dilution included), misalignment with the reported production plan, and increased operational costs due to inefficient use of resources. This study, conducted at Los Bronces Mine operated by Angloamerican, Chile, addresses the application of a three-dimensional simulation tool that, through numerical modeling, is capable of predicting post blast rock displacement. The implementation was carried out in a pit phase characterized by blasts near the pit boundaries, with a high risk of material spillage and potential blockage of the only access ramp to the extraction levels. By the integration of key design parameters, such as blast pattern geometry, detonating time, explosive charge distribution and pre and post blast survey, an optimal calibration was achieved and validated in seven blasting events to date, reaching an accuracy greater than 80% in estimating post-blast rock displacement and spillage volumes. Furthermore, this study allowed the evaluation of different pattern alternatives with and without spillage mitigation measures (use of air decks near the free face), obtaining a high correlation and accuracy exceeding 95% in predicting the selected design outcome, supporting optimal design selections. The result highlights the usefulness of the model as a decision-support tool for blasting engineers and short-term planning, by reducing the need for unnecessary operational reworks, improving geological and operational reconciliation, and ensuring the alignment of the extracting plan with production targets. The current average deviation is 15%, with higher deviations observed in blasts with smaller volumes of spill or where the simulated sequence was changed before blasting. The use of this type of three-dimensional numerical modeling represents a significant advancement for blast engineering and the optimization of key performance indicators in open-pit mining operations.

Jan 26, 2026

By Charles S. Allbright, Frank G. Schwartz, Marvin L. Whisman

Radioactive tracer techniques were used to gain a better knowledge of the types of compounds that cause gum formation in gasoline during storage . A selected organic compound was labeled with tritium and purified . An unstable gasoline was tagged by adding a small amount of the labeled compound . After storage of the gasoline at 110 ° F for 16 weeks , the gum that had formed was recovered . The amount of the test compound converted to gum was determined by liquid scintillation counting . About 70 compounds , including several classes and types , were studied . The compounds , listed in order of descending reactivity in the test fuel , were sulfur compounds , nitrogen compounds , polycyclic hydrocarbons , olefins , alkylbenzenes , and saturates . In the order of decreasing percentage of each in the gum , the compounds were monoolefins , alkylbenzenes , sulfur compounds , polycyclic hydrocarbons , nitrogen compounds , and diolefins . This type of information should be helpful in developing a method for predicting the storage stability of gasoline .

Jan 1, 1964

By G. Bitsianes

An experimental procedure was developed for studying magnetic roasting on a accurately-controlled laboratory scale. The loss-in-weight method was used and the course of reduction could be followed under a reducing gas atmosphere containing as many as five different components. Some important variables of the operation were checked on a marginal Mesabi iron ore containing porous and dense varieties of hematite as well as pure goethite. The conditions simulated were those for the grate roasting of a coarsely-sized ore burden. Temperature was maintained at 600°C; gas composition at 4.25% CO, 4.25% H2, 17.0% CO2, 15.0% H20, and 59.5% N2,, and gas flow rate at about 1,5 lineal feet per minute. The ore charge was composed of quarter-inch cubes. Under these conditions, the ore porosity was found to be one of the governing variables of the operation. Results showed that an ore size limitation existed as a function of this ore porosity. For efficient magnetic conversion, the size limit was 3/8 inch for very porous ores and about 65 mesh for very dense ores. An anomaly was noted in the weight losses incurred during actual magnetic conversion. For goethitic ores, these were generally about 13 per cent higher than could be accounted for theoretically. The effect was attributed to possible non-stoichiometric structures forming during the reduction process.

Jan 1, 1960

By Earle S. Burnett

This report outlines the experimental procedures for using a Burnett apparatus to obtain compressibility coefficients for multiphase, multicomponent fluid mixtures. The conventional Burnett method is described briefly whereby multiphase compressibility data can be obtained by first determining the compressibility factor, Z, as an isothermal function of pressure alone. Then starting at conditions of temperature and pressure where Z is known, the fluid is cooled at constant volume to some lower temperature at which the resulting pressure is measured, and a corresponding value of Z is obtained from a fundamental relationship between compressibility factors, pressures, and temperatures at constant volume. The isochoric treatment of the fluid, extended to still lower temperatures and along other isochors, eventually results in compressibility determinations for the whole two-phase system thus covered experimentally.

Jan 1, 1963

By Deborah A. Kopsick

Several minerals were observed and collected in a small gully originating from a weathered coal processing waste (gob) pile in Barton County, Missouri. The rapid alteration of these various minerals after collection suggested that they might represent a dehydration sequence. X-ray diffraction of the dehydrated and rehydrated minerals deposited on the gob pile indicated the presence of the monohydrate and heptahydrate forms of ferrous sulfate, szomolnokite and melanterite respectively. The occurrence of melanterite (FeSO4.7H2O), was limited to isolated areas of ponded water while szomolnokite (FeSO4.H2O), was associated with the outwash areas of the pile. Laboratory dehydration of melanterite collected at the gob pile revealed the formation of rozenite (FeSO4.4H2O), an intermediate form of ferrous sulfate. Szomolnokite was shown to be the stable form of these ferrous sulfates during these experiments while melanterite and rozenite were shown to alter readily. Chemical analysis of szomolnokite revealed enrichment in Fe, Mg, Zn, Cd, Cu and Mn relative to the chemical composition of the gob ad the lechate generated from the gob wastes. Although this gob pile had been weathering for more than 35 years, significant concentrations of trace metals were still being released from the pile through the generation of leachate and the formation of various soluble metal enriched ferrous sulfate minerals.

Jan 1, 1982

By T. L. Joseph

"IntroductionThe efficiency of ore reduction in the blast furnace and fuel requirements depend upon the degree of uniformity with which reducing gases can be distributed through the stock column and upon the permeability of individual pieces of ore and sinter. If the ore is fine, the major problem in reduction is to get the ascending gas stream to the surface of the ore-Hard, dense ores of low permeability, mined in coarse sizes, tend to improve the permeability of the bed, but unless they are crushed to the proper size they reach the hearth unreduced.Surveys by the Bureau of Mines have shown conclusively that the gas distribution in the upper three fourths of the furnace is far from ideal. Furnace lines, top design, and methods of charging are important, but more thorough size preparation of the ore is necessary to eliminate size segregation at the stock line, which inevitably leads to non-uniformities in gas distribution.Because of the quantity of sinter now produced close study of the characteristics which determine its behavior in smelting is warranted. As the use of concentrates increases agglomeration will become more of a necessity. Improvements in the physical character of the ore burden are particularly important to plants using coke of poor physical quality. In addition to aiding reduction, improved physical properties of the ore burden will permit the use of higher blast heats, which is equally important.Reduction Tests on Fine Sizes of SinterPrevious reduction tests on minus 0.742— plus 0.525--inch pieces of commercial sinters revealed large differences in porosity and reducibility. The results have been published in a former report. 3 Although the physical properties of the sinter, particularly porosity, were found to be of major importance in determining the rate of deoxidization, it appeared that certain chemical properties of the sinter appreciably retarded the reduction of sinters high in silica. This was attributed to the presence of fayalite, which has been identified by Schwartz and by Luyken and Kraeber4 as an important constituent of sinter. Although furnace operators and metallurgists have assumed that iron silicate is more difficult to reduce than hematite or magnetite, definite data on the reduction characteristics of this material were not available. Tests were undertaken, therefore, to develop a method for de-termining the amount of iron silicate present in sinters so that its effect upon reduction could be observed."

Jun 1, 1934

By James J. Olson

Most of the projects summarized in this paper are funded under the Bureau's Advancing Metal-Nonmetal Mining Technology program and are part of the in situ mining subprogram coordinated at the Twin Cities Mining Research Center. The borehole mining equipment development, are funded under the Bureau's Advancing Coal Mining Technology program, is essential to accelerated progress in the in situ mining subprogram, and some background information on this concept is included. The initial in situ research projects started in 1971-72 evaluated some of the critical blast design parameters for in situ copper leaching. The present program totals about $1 million per year and includes in-house research projects, cooperative (cost-sharing) projects with the mining industry, and research and development contracts. Two different extraction schemes are under investigation: inplace leaching and borehole (or slurry) mining. The principal commodity targets for the Bureau's improved in situ mining technologies include copper, uranium, coal, and potash. The principal purpose of this paper is to inform the mining industry of the in situ mining research recently completed or being conducted by the Bureau of Mines. In addition the Bureau encourages companies to comment on the program accomplishments as well as offer suggestions on top priority research needs for improving the in situ mining methods described in this paper.

Jan 1, 1977

By M. Bryson, J. Taguta

The Prieska deposit, mined between 1971 and 1991, is one of the world’s top thirty volcanogenic massive sulphide (VMS) base metal deposits. The Prieska Copper Mine in the Northern Cape Province was closed by Anglovaal when underground mining had extended to depths which did not allow for safe and economic extraction of the deposit at the time. The mine has a recorded historical production of over 1 Mt of zinc and 430 k tonnes of copper from 46.8 Mt of milled sulphide ore, achieving life-ofmine metal recoveries of 85% for copper and 84% for zinc into high quality concentrates (refer ORN ASX release 15 Nov 2019). Orion Minerals Ltd is currently investigating the feasibility of developing a new mine in the footprint of the historical Prieska Copper Mine, using the extensive remaining infrastructure, with the intent of extracting the unmined zinc-copper mineralisation from the Prieska deposit. This paper reports results on the flowsheet development philosophy on the hypogene ore, and challenges encountered in the process. This study initially failed to replicate historic copper and zinc recoveries employing the historic production flowsheet and reagent conditions unmodified on bench scale, as the copper and zinc were co-floating. Flowsheet modifications were therefore made to improve differential flotation and recovery, resulting in achieving comparable saleable products and recoveries from processing the hypogene ore on bench scale. Flotation variability test work on the hypogene ore focused on the use of the original flotation procedure and reagent suite using a sodium cyanide-zinc sulphate depressant system on the copper circuit, and it generated a saleable copper product of 20-26% Cu grade at 80-86% recovery. The zinc circuit generated a saleable zinc product grading at 48-55% Zn at 80-94% recoveries. Some zinc losses were due to the deportment of some zinc in sauconite. It is recommended that further test work may further improve the copper grades and recoveries. Keywords: Prieska, flotation, hypogene ore, flowsheet development, sulphide flotation, reagents

Jan 1, 2020

By T. G. Davies

The paper presents design equations for singly laterally loaded piles embedded in sand. These equations were obtained from a comprehensive nonlinear analysis of free and fixed head piles subjected to horizontal loads. The sand is modelled as an elastic-perfectly plastic material whose strength and stiffness are proportional to depth below ground level. The soil's response is described by means of a boundary element representation of the continuum while the pile itself is created as an elastic beam. Equations for the latter are derived directly from the Bernoulli-Euler theory and are coupled with those describing the non-linear soil response. The effects of bearing failure along the front, face of the pile, shear failure along its sides and tension failure at the back face are accounted for in the analysis. Simple equations are presented to describe both the elastic and inelastic responses. The only sol parameters required to use these equations are the angle of internal friction of the sand and a parameter characterizing the rate of increase of the sand's modulus with depth. The latter can be taken as equivalent to the modulus of subgrade reaction. The results of this analysis show that soil yielding is very significant at working load levels, resulting in substantial increase in bending moments and lateral deflection.

Jan 1, 2010

By D. Spitty

There are enormous complexities with mine planning and the problem itself presents a huge challenge to the existing mine planners performing this activity. Mine planning optimization supports planners to determine ?What are the best increment excavation sequence and the best material blending combination such that throughput, quality, cost, utilization and Net Present Value (NPV) targets are met?? It is achieved through using an advanced scientific approach that has been specifically adapted to address the mine planning dilemma.

Feb 23, 2014

By Guojun Qi

This work relates to wafer bumping technologies for flip chip packaging applications in the electronics industry. Nickel and its alloys are alternative under bump metallization (UBM) materials because of their slower reaction rates with Sn-based solder as compared to Cu-based UBMs. In this study, we compared the morphologies of the intermetallic compounds (IMC) formed between Sn-bearing solders (Sn3.5Ag and eutectie Sn-Pb) and two types of nickel- based UBMs, electro less Ni-P (EN) and sputtered nickel. Both chunky-type and needle-type of intermetallics were observed between the EN UBM and the solders. In the case 'of sputtered Ni UBM, there is only a layer of scallop-type intermetallics formed, The morphology change and growth kinetics of the IMC in thermal aging process were analysed. Kirkendall voids were noticed from samples ofSn3.5Ag solder vs Ni-P UBM that have undergone prolonged thermal aging at high temperature.

Jan 1, 2003