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By D. A. J. Swinkels

The problem of determining oxygen levels in liquid steel to aid in deoxidation control has received general attention for a number of years. Work in this direction started at the B.H.P. Central Research Laboratories early in 1967 with an evaluation of sampling techniques followed by vacuum fusion analysis to determine the oxygen content of the samples (1). It was found that these techniques had a number of drawbacks if they were to be used for deoxidation control. The method of analysis was rather too slow to allow effective control and measured total oxygen level rather than dissolved oxygen. Furthermore, the results were found to be very variable due to slag entrainment in the samples. Attention therefore turned to the galvanic cell method using a solid oxygen ion conductive electrolyte such as cubic stabilised zirconia. The ionic conductivity properties of electrolytes such as (ZrO2) 85 (CaO).15 had been studied by a number of investigators and had already been applied to the measurement of oxygen activity in gases, in lower melting metals such as copper, lead, tin, silver, alkali metals and indeed the first studies in steel had been made (2,3). Since then the results of a number of studies in the development of an expendable oxygen probe for steel have been reported (4-9).

Jan 1, 1972

By Paul T. Allsman

THE THREE words, research, mechanization, and automation are keynote words for mining technology during 1962. Basically interrelated, they not only express the major technologic developments in mining but are the signposts pointing out the road ahead. The process represented by each of these words is evolutionary rather than revolutionary, but developments during the past year indicate a climactical stage has been reached in the process of evolution. Mining research has progressed beyond the stage of academic discussion and is a programed activity within the Federal Government,3 the mining colleges,4 and many of the large mining companies.5 Research was a major agenda item at various national and international mining meetings in 1962. A list of these meetings would include such diverse locales as the Workshop and Symposium on Computers and Computer Applications in Mining and Exploration at the University of Arizona in March; and the 5th Rock Mechanics Symposium at the University of Minnesota, in May; the Rock Mechanics Symposium at McGill University, Montreal, Canada, in September; and the Colloquium XIII, International Society for Rock Mechanics, at Salzburg, Austria, in November.

Jan 1, 1963

By Mckenzie CK, Scott A

The injection of coal as an auxiliary fuel in ironmaking blast furnaces has been introduced on many furnaces worldwide. This paper examines the present practice of coal injection and discusses future directions for the technology. This has been undertaken through the use of a heat and mass balance model which predicts the replacement rates of coke by coal and the effect of coal injection on blast furnace productivity. The results indicate that future pulverised coal injection could replace substantial quantities of metallurgical coke, but that the energy balance economics of individual steel plants will have a dominating influence on the future of the technology.

Jan 1, 1987

By D Ziaja, W Jaspers

A brief history of the development of pneumatic flotation cells from early in the 20th century to the present day and a comparison to conventional cells demonstrates the efficiency and simplicity of design and operation of the ænew generationÆ of pneumatic cells. Recent successful testwork on phosphate minerals in the USA and a variety of coal types in Australia confirm the utility and efficiency of the design. The key aspects of this technology are improved recovery and selectivity with lower capital expenditure and operating costs.

Jan 1, 2005

By Y. Miyabayashi, K. Nishikawa, H. Nagai

JX Nippon Mining & Metals Group recovers valuable metals from end-of-life electronic products in an economical and environmentally-benign way, based on technologies that have been acquired in mining, smelting, and refining operations over time. End-of-life electronic products contain halogens and hydrocarbons. When such materials are treated in the copper smelting process, corrosion of equipment and discoloration of sulfuric acid occur. As a countermeasure to these problems, we have developed pretreatment processes that include an incinerator, exhaust gas washing towers, and a defluorination facility. By implementing these improvements, we have been able to treat a large volume of end-of-life electronic products efficiently in the copper smelting process.

Jan 1, 2014

By Li-min Liu

The Semi-Analytical method can be used to solve a variety of problems in geomechanics and civil engineering. When it comes to layered rock strata and rock masses, it is superior to all other analytical methods. This paper presents the application of a 3-D semi- analytical method to 3-D surface subsidence and stress analysis caused by mining. In this semi-analytical method the layered elements and triangular elements ate used alternatively. Their displacement pattern, strain mahix, elastic matrix, stiffiness matrix, load matrix and stress matrix are presented. A numerical simulation program based on the semi-analytical method bas been developed using Fortran 90. This program is suitable for subsidence prediction and stress analysis of mom and pillar mining, strip longwall and mechanized longwall mining methods. It is applicable to all geological conditions and mining methods. Comparing with the finite method, this method reduces significantly the number of simultaneous equations to be solved and the amount of data preparation. It not only reduces the computer memory, but also runs faster and cost less. Key Words Semi-analytical method, surface subsidence, stress analysis, layered element, triangular prism element

Jan 1, 2002

By H. J. Freyn

The American iron and settl manufacturer finds himself to-day barely at the threshold of enormous possibilities for practicing rational economy in the use of fuels.

Jan 1, 1915

By Ernesto Villaescusa, Andres Brzovic

Rock masses of the primary copper ore at the El Teniente Mine are very competent and massive. The rock mass contains almost no open discontinuities. Nevertheless, there is a high frequency network of small discontinuities coupled with widely spaced faults. A data collection campaign designed to characterize the rock structure was recently implemented. The results show that conventional analysis in terms of discontinuity frequency does not predict differences between two studied sectors. However, when an empirical definition of a weak discontinuity is applied, appreciable differences between the two sectors appear in terms of discontinuity frequency and predicted in situ block size distributions. These differences are in accordance with actual observations at the mine site. Due to the geological features of the primary copper ore, rock mass classification schemes cannot be readily applied to characterize these rock masses.

Jan 5, 2007

By David Sainsbury, Bevan Thompson, Yuejun Cai

The practice of placing loose rockfill as passive support in open stoping voids, of narrow vein mineral deposits, lends itself to the sterilisation of substantial mining reserves in the requirement for regional crown/sill pillars. Significant benefits are to be gained by the Australian mining industry via the development of improved guidelines for the extraction of such sterilised mine pillars. The application of selectively injecting specifically developed ettringite (calcium sulphoaluminate hydrate) type cement grout into loose rockfill, enables an artificial pillar to stabilise the surrounding rockmass and prevent the caving of loose rockfill from the previously backfilled void during extraction of remnant crowdsill pillars. This paper presents the results of laboratory testing used to reduce the technical risks associated with the design of cemented rockfill pillars. A laboratory testing program was devised to investigate the critical parameters influencing the performance of a stabilised rockfill matrix, along with the critical parameters influencing the interpretation of laboratory test samples. The factors investigated include; sample size and shape, particle size distribution, curing time, water quality, cement : water ratio and the confinement effect.

Jan 1, 2001

By Rais SA

In June, 1986, Freeport Indonesia, Inc., in conjunction with Out- okumpu USA, laboratory tested the Flash flotation concept on Primary ball mill underflow. These laboratory results indicated a possible 10% increase in precious metal recovery and 0.6% increase in copper recov- ery were available over conventional methods. By October of the same year two Outokumpu Skim Air SK-240 units were operational on one mill circuit and were achieving 5 to 10% increased recovery in precious metals with equal copper recovery at one percent higher final concentrate grade. Two more cells were purchased and installed on the remaining grinding circuit in July, 1987. As part of the installation of the Skim Air cells, an existing cluster of six 508mm Krebs cyclones were replaced by four 660mm Krebs cyclones. To reduce high circulating loads, these new cyclones were made horizontal at 45 degrees. This arrangement succeeded in reducing the mill circulat- ing load by 100% and has allowed for a 10% increase in throughput at the same grind.

Jan 1, 1988

By S. Özgen

In this study, the possibility of beneficiation of chromite tailings in the Uckopru/Fethiye-Turkey region by a combination of hydrocyclone and multigravity separator (MGS) was investigated. The two significant operational parameters of hydrocyclone, which were diameter of the apex and diameter of the vortex, and the three significant operational parameters of the MGS, which were drum speed, tilt angle, and wash water, were varied and the results were evaluated with the central composite rotatable design. In order to produce a chromite concentrate by hydrocyclone and MGS, mathematical model equations were derived by computer simulation programming, applying the least-squares method using Minitab 15. Second-order response functions were produced for the grade and recovery of chromite concentrates.

Jan 1, 2012

Develop a reliable, portable device for non-destructively testing the support integrity of a friction rock support (commonly referred to as a Split Set ). Approach The friction rock support, used to support mine roof and ribs, is a slotted tube driven into a drilled hole of smaller diameter. Upon installation, the tube is compressed radially. The amount of compression is a function of the hole diameter, the strength of the host rock, and the properties of the split set itself. A simple lightweight self-contained device was developed to determine the pull-out resistance of the friction rock supports in-situ, based on measurements of the tube's deformation. The tester measures the com-pressed internal volume of the slotted tube, which has been found to provide an estimate of the support's resistance to pull out. How It Works The tester consists of a pump and expander sections. The expander sections are made from an elastomer membrane which is stretched over two cores, each one inch in diameter and twelve inches long. The expanders are connected by a flexible coupler so that they can fit any alignment of the support.

Jan 1, 1984

By James M. Tennant

In the mid 1970's, American Electric Power significantly expanded its internal coal production. This involved opening several large mines in seams that had never been mined on a large commercial scale before. One of the mines opened was the Martinka No. 1 Mine which is located approximately five miles southeast of Fairmont. The mine was originally designed for room and pillar mining with continuous miners but was later modified to permit the utilization of longwalls and continuous miners for entry development. The coal seam to be mined was the Lower Kittanning which averages fifty-six inches. In order to successfully mine this seam, it required that the mine design recognize the effect caused by the dip of the seam which averages four percent to the Northwest with a maximum of sixteen percent for short distances and a relatively low cover. In fact, seventy-four percent of the reserves have cover of less than four hundred feet. Also, the core hole data indicated that the immediate roof varied from zero to eighteen feet of shale with two to forty-five feet of sandstone overlying the shale.

Jan 1, 1982

By Douglas J. Uhren, Gary W. Gilbert

This paper describes the risk elements associated with difficult glacial geology, including boulders, heavy groundwater inflow, and potential running soils all coupled with a potentially corrosive service environment. The matrix workshop for the 168-inchfinished diameter sanitary sewer interceptor tunnel in Columbus, Ohio is assembled with the Design Team and the Owner’s design, operations, and fiscal staff. Corrosion protection alternatives are compared against cost and non-cost parameters with relative risk and weighting factors assigned. The Owner working in cooperation with the Design Team uses the matrix workshop to se

Jan 1, 2001

By Venkata S. Vutukuri

Compressive strength of cylindrical specimens of a model material and sandstone with various diameter/height (d/h) ratios was determined in unconfined compression tests. It was observed that the compressive strength increases with increase in d/h ratio. Triaxial compression tests were also conducted on the specimens of the same materials with a d/h ratio of about 0.47. It was observed that the axial stress at failure increases with increase in confining pressure. A very interesting correlation was found between the effect of d/h ratio on compressive strength in unconfined compression tests and the effect of confining pressure on axial stress at failure in triaxial tests. The relationships between d/h ratio and confining pressure, s3 in MPa are:- For model material - s3 = -0.95 + 1.7957*(d/h) 0.7883. For sandstone - s- (-0.4554 + 0.9888* (d/h) 1.0355. The correlation coefficients for these equations are 0.9997 and 1. These equations are valid for d/h ratios of up to 10.

Jan 1, 1993

By Randy Sandrik

Sampling has evolved at two large underground limestone mines as conditions and product requirements have grown tougher over 100 years of mine life, requiring innovative techniques to insure delivery of high purity limestone. Sampling insures delivery of consistent product to customers at the lowest possible cost. Statistical considerations have evolved from simple data collection to predictive and process capability analysis. Sample methods include borehole samples, face (using a proprietary face-sampling device), and total plant feed automatic, process, and final product sampling. Lessons learned, while keeping costs at historically low numbers, include the importance of geological models, exploration drilling density, face sampling, and blending of ore.

Jan 1, 2005

By D Giles

We present plate tectonic reconstructions, showing that porphyry-type ore deposits are spatially and temporally linked to ridge subduction. A reconstruction of the Peruvian subduction system reveals an immediate metallogenic response to the arrival of the Nazca Ridge at the subduction trench, followed by southward migration of the zone of metallogenic activity due to the lateral migration of the zone of ridge subduction. A similar pattern is recognised in central Chile , where the spatio-temporal distribution of giant ore deposits coincides with the arrival of the Juan Fernandez hotspot chain at the subduction zone. We conclude that there is a spatial and temporal link between ridge subduction and ore deposit formation, with high metal fluxes concentrated in zones of ridge subduction. Thus, the recognition of tectonic patterns associated with ridge subduction can provide insights into predictive mineral discovery by enhancing our ability to predict the position of large mineral deposits in other modern and ancient orogens. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By C Philander

The West Coast of South Africa is well known for its placer gem quality diamond deposits and also associated with these hosts of Cenozoic unconsolidated marine and aeolian sand and gravel are significant concentrations of heavy minerals. Exploration for economic concentrations of zircon, ilmenite and rutile along the coast started in the mid-1980s. This resulted in the discovery of an inferred 1.6 billion tonne resource with a grade of ten per cent total heavy minerals (THM), which developed into the Namakwa Sands Mine, a world-class producer of heavy minerals. Several other resources, including satellite deposits proximal and distal to the mine area, extensive diamond mine dumps and present day beach placers, demonstrate the vast heavy mineral potential along the West Coast. The favourable gangue to economic mineral ratio, a higher zircon content compared to other similar deposits, relatively lower U+TH content of zircon, low slimes content and effectively pristine low chromium-manganese ilmenite of these deposits, render them attractive exploration targets. Negative factors that will affect conventional mineral beneficiation and liberation include secondary mineral coatings and the regional coastal development of several layers of superimposed duricrust. The economically attractive heavy mineral assemblage along the West Coast is the result of erosion of the proximal, gneissic Namaqualand Metamorphic Province and mature Table Mountain Group sandstone, concentration by marine and aeolian processes and preservation under arid climatological conditions over a period of more than 100 Ma.

Jan 1, 2008

By Maxwell HW

Pacific Coal Pty Limited (a wholly owned subsidiary of CRA Limited) managed the interests of six members of a joint venture formed to mine and export eight million tonnes of export quality steaming coal from a mine developed at Blair Athol in the Bowen Basin of the Central Queensland coal fields. The mine is now operated by Blair Athol Coal Pty Ltd. Crooks Michell Peacock Stewart Pty Limited (CMPS) was awarded a project management and engineering contract for the total mine portion. Following a feasibility study, CMPS carried out an Optimisation Study which produced changes to the design of the project, thus resulting in the project budget being reduced by some A$13 million. In spite of a number of late additions to the scope of work, the project was completed at a final cost of A$148 million, many millions below the reduced project budget. The project was also completed several months ahead of schedule. Total services were provided to take the project from feasibility stage through to the establishment of an operational facility and included project management, planning and control, accounting and financial control, as well as the organisation of engineering, procurement, construction, industrial plant commissioning, and technical training matters.

Jan 1, 1986

By David Hersey

The Paseo Bridge was located at the I-29/I-35/US-71 Missouri River Highway Crossing. It was built between 1952 and 1954 by Massman Construction Company. The 1,232 foot long, self-anchored suspension bridge was the longest of its type when built. On Jan. 22, 2003, a connector pin designed to allow the bridge to expand and contract during temperature cycles seized and caused a portion of the bridge deck to raise up and block traffic. This marked the beginning of the end for the old Paseo Bridge.

Jan 1, 2013