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By S. Doombos

To convert the railway-bridge across the Oude Maas between Dordrecht and Zwijndrecht into a vertical lifting bridge, a drastic adaptation of the existing piers is necessary. Extra piles have to be placed quite close to the present piers to bear the extra weight of lift-towers and bridge-sections. This article describes the special technology applied to drive steel tubular piles l800 mm. in diameter and 36 m. in length vibration-free into position. At the same time a method of pile-point-reinforcement has been applied to minimize the settlements.

Jan 1, 1989

The primary use of coal in the US is for electric generation. The problems associated with the use of this vast amount of coal is the central theme of these sessions. The problems discussed include: production capacity, mining problems, coal cleaning, transportation, combustion, and various environmental problems, such as health effects of coal combustion, water and air pollution, and solid waste disposal.

Jan 1, 1979

By Joseph N. Bakambu

It is currently recognized by mining society that autonomously guided underground mining vehicles may greatly increase the efficiency of mining production and improve human safety. Recent results in mobile robotics, data fusion and sensor development provide a solid basis for solving the problems related to autonomous underground navigation. Recently developed commercial systems mostly rely on the infrastructure that is expensive and difficult to maintain. Guideless navigation in unstructured and harsh environment of underground mines is still a challenging task. In this paper, we describe an autonomous navigation system for an underground mining vehicle equipped with on-board dead reckoning, inertial and optical sensors. This system does not require any artificial infrastructure and is capable to guide the vehicle along the complex environment of interconnected underground drifts; it also ensures the detection of obstacles on the vehicle path. The user interface for monitoring and control is described and the results of laboratory tests and on-site experiments are presented. Work in progress addresses the system integration for real equipment, and the system upgrade, adding map-building and selflocalization capabilities .

May 1, 2002

By Lixun Kang

Bedded structure is the characteristics of coal measures strata. Bedding planes, coal streaks and soft rock bands existing in roof strata destroyed its continuity in the direction perpendicular to the coal seams. The statistics from a large number of long wall faces in which serious roof fall accidents occurred in Datong coal mining area suggest that beddings planes, coal streaks, soft rock bands, especially the first layer thickness of immediate roof have a great influence on its stability. As the first layer thickness increases, the probability of serious roof fall accidents decreases. Based on the investigations finite element method is used to analyze stress and displacement in the first layer of immediate roof. The results indicate that the thicker the first layer is, the less the roof convergence in the unsupported area is. Stress and strain features in stratified immediate roof are quite different f7om those in non- bedded immediate roof. In stratified immediate roof, every stratum has each own tensile zone in the upper portion and compressive zone in the lower portion, while tensile zone in the first layer is less, the tensile stress is the greatest.

Jan 1, 2005

By Konstantinos Komnitsas, Evangelos Petrakis, Emmanouil Varouchakis

During the modeling of grinding systems, population balance modeling (PBM) which considers a constant breakage rate has been widely used over the past years. However, in some cases, PBM exhibited some limitations, and time-dependent approaches have been developed. Recently, a non-linear framework which considers the traditional linear theory of the PBM as a partial case was introduced, thus allowing the estimation of product particle size distribution in relation to grinding time or the specific energy input to the mill. In the proposed model the simplified form of the fundamental batch grinding equation was transformed into the well-known Rosin–Rammler (RR) distribution. Besides, the adaptability and reliability of the prediction model are among others dependent upon the operating conditions of the mill and the adjustment of the RR distribution to the experimental data. In this study, a series of grinding tests were performed using marble as test material, and the adaptability of the non-linear model was investigated using three loads of single size media, i.e., 40, 25.4, and 12.7 mm. The results indicate that the proposed model enables a more accurate analysis of grinding, compared to PBM, for different operating conditions.

Jun 24, 2023

By Fred W. Snow

This paper describing the mining practices at the Magma mine, Superior, Ariz., is one of a series being prepared by the Bureau of Mines on mining prac¬tices, methods, and costs in the various mining districts in the United States. At present (1929) practically all the mineral production in the Superior district is from the Magma mine of the Magma Cooper Co. The ore is mined for its copper but contains associated silver and gold. Both direct smelting ore and ore of concentrating grade are produced. The mining methods now in use at the Magma mine were adopted or developed as knowledge was gained of the physical condition of the ore bodies and the inclosing formations; the wall rock is soft and crushed and the ore is relatively hard. In general, existing methods have been adapted to fit local conditions, but some of the mining practices used were originated at this mine. Most of the ore is mined by a combination of rill stopes and pillar stopes. The pillars are extracted by underhand mining.

Jan 1, 1929

By A. M. Milev

A simulated rockburst was conducted underground at Kopanang Mine, previously called Vaal Reefs No. 9 Shaft. The rockburst was simulated by means of a large blast detonated in solid rock close to a crosscut sidewall. The simulated rockburst involved the design of the seismic source, seismic observations in the near and far field, high-speed video filming, a study of rock mass conditions such as fractures, joints, rock strength etc. Knowledge of the site conditions before and after the simulated rockburst was also gained. Some of the important findings are listed below: ?Two areas of damage were identified on the blasting wall: (i) an area of high-intensity damage in which ground velocities of 3.3 m/s were recorded by an accelerometer, which was subsequently ejected in a block of rock, (ii) an area of low-intensity damage where ground velocities of 1.6 m/s were recorded by an accelerometer which remained on the tunnel wall. ?High-speed filming revealed rock fragments being ejected from the wall at velocities in the range of 0.6 m/s to 2.5 m/s. The measurements were taken in the area of low-intensity damage. As planned, no gas pressure was directly involved in damaging the wall of the tunnel. ?The attenuation of peak particle velocities for the main blast in the near field (6 m to 30 m), as a function of distance R, was found to be proportional to R-1.7. ?The simulated rockburst was recorded as a local magnitude ML= 1.3 by the Klerksdorp regional seismic network. ?Peak particle velocities from nearby blasting, recorded on the tunnel wall after the simulated rockburst, were about six times greater then peak particle velocities recorded from the same source area before the simulated rockburst.

Jan 1, 2001

By Hal T. Morris

The main Tintic mining district in central Utah has produced approximately 13,500,000 tons of ore, containing silver, lead, gold, copper, zinc, and other metals, valued at more than $315,000,000. More than 90 per cent of this ore has come from large, irregular ore bodies that have replaced folded and faulted limestone and dolomite strata. Of lesser importance are replacement veins that chiefly cut contact-pyrometasomatized carbonate rocks and fissure veins that cut altered intrμsive bodies and volcanic rocks. The district is in the west-central part of the East Tintic Mountains, a north-trending fault-block range near the eastern margin of the Great Basin. The consolidated sedimentary rocks exposed at the surface and in mine workings are miogeosynclinal deposits more than 10,000 feet thick that range in age from late Precambrian to Late Mississippian. They are folded and strongly faulted and are partly overlain by volcanic tuffs and agglomerates and by extensive flows of porphyritic and vitrophyric quartz latite, latite, and trachyandesite of Eocene age. All of these rocks are locally concealed beneath thick alluvial deposits of Pliocene and Quaternary age. The Eocene and older rocks are cut by dikes, sills, and small stocks of porphyritic quartz monzonite, monzonite, and latite, which are genetically related to the ore deposits. The district is inactive except for the production of halloysite clay and for minor leasing activity and exploration ventures. Several exploration targets remain untested.

Jan 1, 1968

By David H. Tang

Massive pillar failures were observed at two underground coal mines. The results of stability analysis using traditional pillar design formulae did not agree with the underground observations. Finite element models were used to analyze the causes and mechanisms of the pillar failures. The results were confirmed by the underground observations. Finally, the improved mine plan for each case was derived to ensure the stability of the underground structure.

Jan 1, 1990

By A. R. Barnes, N. O. Lotter

Recoverable economic copper sulphide minerals such as chalcopyrite, bornite, chalcocite and covellite often occur together in varying proportions in the major copper-bearing ores, and have individual flotation requirements and characteristics. Pyrite also occurs in these ores to varying extents as the sulphide gangue, and is problematic because of its natural tendency to float quickly and easily. In a bulk sulphide float, selectivity against pyrite is desirable, particularly if it does not host other paymetals such as gold or silver. At the same time it is a requirement to float all of the copper sulphides despite their electrochemical differences. The electrochemistry and semiconductor properties of these minerals are reviewed, together with implications for flotation with and without collector addition. Mixed collector systems for the improved flotation of these sulphides are proposed as a solution. The use of xanthate and dithiophosphate in the collector suite allows the co-existence of dixanthogen and free dithiophosphate radical because the latter has a higher redox potential requirement than xanthate to oxidise to the dithiolate. Because some of these minerals require dixanthogen, and others, free thiolate, to generate surface hydrophobicity, a bulk flotation of all the species becomes possible in the overlapping area of Eh and pH between the two dithiolate equilibrium lines on the Pourbaix diagram. The arsenic-signature copper minerals are added to the study, since many copper operations encounter arsenic as a penalty element in the saleable concentrate. It is shown that the addition of arsenic to the copper and iron sulphides alters the semiconductor and electrochemistry properties, and in turn, its flotation characteristics. The degree of mineral association and liberation between these minerals can be a complicating factor due to textural associations, and should also be considered in the process as a next step.

Jan 1, 2016

By Guy Ervin, Delwin D. Blue, John E. Conley

"INTRODUCTION Extraction of alumina from various materials, such as low-grade bauxite and clay, by means of a lime-soda sinter has been the subject of a number ofinvestigations (1, 2, 3, 4, 5, 7, 9, 10, 11, 12, 13, 16, 17). 5/ in recent years, Although many of the details of these investigations are lacking, it is believed that there is one difficultly that frequently develops under certain conditions, namely, that of thickening or gelation of the slurry formed during extraction of the sinter. If gelation occurs even to a slight extent* Serious mechanical difficulties result, very low liquor recoveries are obtained, and the extraction step becomes virlually inoperable. Under 'favorable conditions, a solid gel is formed which can only be removed from the equipment with great difficulty. At the Eastern Experiment. Station of the Bureau of Mines in College Park, Md., a study of lime-soda processes was begun in November 1941. This work has included studies on low-grade bauxites, kaolin clay, and nodular diasporic clay. Gelation was most serous with kaolin clay and least with diasporic clay. As a part of the Bureau's investigation, a study was made of the effect of the pertinent variables on gelation. The results permit the selection of various sets of conditions at which gelation will not occur. These data are essential to the final selection of optimum conditions for the over-all process."

Aug 1, 1946

By B B. Du, Y N. Lu, L X. Wang, S L. Wu

The cohesive zone in the blast furnace is largely affected by the softening and melting behaviour of ferrous burden because of its vital role in the blast furnace process. The Visual High Temperature Methodology (VHTM) has been given to study the softening and melting behaviour of sinter, two kinds of lump ores and acid pellet intuitively. Before softening, both two kinds of lump ore swelled and more serious for lump ore B because of its denser structure than lump ore A. The softening and melting temperature intervals are different from one another and this phenomenon contributed to the gas permeability of ore layer in the cohesive zone since the ‘ore window’ has formed. Besides, the softening and melting behaviour of mixed burdens have been studied, where it has been found that the softening and melting characteristics of mixed burden A (consisting of sinter and lump ore A) is better than mixed burden B (consisting of sinter and lump ore B) and mixed burden C (consisting of sinter and acid pellet) despite the poorest characteristics of lump ore A. The reason is that the high temperature interactivity between lump ore A and sinter is much better than lump ore B and acid pellet. The high temperature interactivity is mainly influenced by the chemical compositions, porosity and contact condition. This paper provides a new research method for the softening and melting behaviour of iron ore and an important technical basis for the optimisation of blast furnace burden.CITATION:Wang, L X, Wu, S L, Lu, Y N and Du, B B, 2017. The softening and melting behaviour of single and mixed iron ore burdens, in Proceedings Iron Ore 2017, pp 605–610 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By William M. Camp

An extensive design phase testing program in which 10 piles and 2 drilled shafts were instrumented and statically load tested to failure, was undertaken to establish relevant foundation design parameters for two bridges in Charleston, South Carolina, USA. The bearing strata at both test sites was a calcareous, overconsolidated, firm to very stiff, slightly sandy, clayey silt (locally known as Cooper Marl). Confirmation dynamic and static loading tests on production piles indicated only 50 to 60% of anticipated pile capacities; including consideration of time effects. Supplemental subsurface explorations did not reveal any significant variations in marl properties. Ultimately, 22 static and 75 dynamic tests were performed on production piles for a 2 mile section of the project. Pore water pressures in the marl were also monitored during and after pile driving. A study of unit skin friction in the marl as a function of time revealed two distinct trends: piles driven in areas with a sand overlaying the marl gained more capacity significantly faster than those driven through a clay or silt. Although the insitu marl properties are apparently similar across the site, the material immediately above the marl evidently has a large effect on pile capacity. This effect of overburden on pile capacity was verified by testing piles over a period of two years.

Jan 1, 1993

By Alfred W. G. Wilson

In this paper is presented a review of the changes that have taken place in certain Canadian non-metallic mineral industries since 1909. The fifteen-year period 1909 to 1923, inclusive, has been selected for two reasons. In the first place, statistical treatment of the subject under review has been nearly uniform throughout the period. In the second place, this decade and a half is itself further subdivisible into three well marked quinquennial periods, the middle one covering the period of the great war when industrial conditions were greatly disturbed. It then becomes possible to institute certain comparisons between equal periods before and after the war disturbances. The items selected for inclusion in this review are certain of the more important members of that class of minerals usually grouped together under the heading of non-metallics. They are all minerals of which Canada is known to possess important resources, and which are indispensable to many of our greatest manufacturing industries.

Jan 1, 1925

Gullies are the vital in-stope excavations that provide access for mining personnel and material to, and mined ore from, the producing faces in the tabular hard rock mines. They pose a serious problem in most mines because they induce stress orientations, which, combined with blast damage, produce adverse rock fracture patterns that contribute to the loss of hangingwall and sidewall integrity. Rock-related injury statistics confirm this by highlighting gullies as the second-highest risk area in South African hard rock mines. Inappropriate gully geometries, poor blasting practice, and non-adherence to accepted standards worsen the problem. The aim of this work is, firstly, to provide guidelines to select the correct gully geometry and appropriate support for a particular geotechnical environment and, secondly, to review the practical issues behind gully safety and stability. In order to meet these aims, this paper reviews the available literature on gullies and their history, and reports on an industry-wide survey of practices and opinions. Then it covers observations from underground visits to 107 gullies situated in the respective geotechnical environments of the Basal Reef, Beatrix Reef, Vaal Reef, Carbon Leader Reef, Ventersdorp Contact Reef, Kimberley Reef, Kalkoenkrans Reef, Merensky Reef, and UG2 Reef. Despite the differing geotechnical conditions and gully geometries, common problems are experienced with geological structure, stress, and fracturing. Results from numerical modelling are also presented to help analyse the underground observations and to quantify the merits of the different gully layouts. It is concluded that there are no new techniques available to improve gully stability, but that significant improvements in safety are attainable by employing the correct gully geometry for the geotechnical environment, good blasting practice, and appropriate support.

Jan 1, 2002

By Y. Paul Chugh

NIOSH and the Illinois Clean Coal Institute are funding studies on characterization of coal and quartz dust in Interior Basin mines since 2009. Coal dust characteristics vary significantly and, are vital for the development of the engineering controls. This paper presents wettability characteristics of coal dust with respect to its chemical and physical properties, since wettability is considered to be a primary dust control technique. Particle size distribution, inter-particle interactions during wetting and quartz associations with organic and inorganic matter in coal seams is critical for understanding wetting phenomena. Silica content in the un-wetted fractions was found to be very high during wetting tests. Wetting of quartz may be limited by its association to hydrophobic materials as well as buoyancy forces resulting from particle size characteristics and particle-particle interaction in the wetting agent. Temperature of the wetting solution and effective contact time between dust particles and water droplets are found to be two important variables affecting the wettability. The characterization data obtained from this study can be utilized to develop engineering controls.

Jan 1, 2011

THE object that the writer has mainly in view in presenting this paper is to draw the attention of those connected with the technical side of the industry to the unsatisfactory and by no means up-to-date methods employed in estimating the tin contents of an ore. At the same time, what is regarded, from the writer's personal experience, as a satisfactory and reliable method is explained in detail. It is a curious fact that for the last 25 years tin·assay methods have made little or no advance, while those now in general use ill connection with copper and lead ores can scarcely be compared with those then obtaining, so greatly have they been improved upon. Though it. is not altogether expected that the method herein advocated will at once meet with general approval, the writer hopes the resultant discussion may bring out points that have hitherto escaped detection.FIRE METHODSThe old Cornish method of smelting with anthracite is now obsolete. The cyanide assay, although unreliable, is still much used because of its simplicity. In the Malaya many buyers of tin ores use the cyanide assay, the smelting being carried out generally in a benzine furnace. It is essential that the smelting with cyanide be performed at a low temperature. Even then, impurities, such as Sb2S3 and...

Jan 1, 1912

The following paper deals with a method for the" Proximate Analysis" of Chloridized Ores, which are free from arsenic, antimony and lime. When these are present the analysis is rendered far more complicated, and many of the methods which I am about to describe could not be applied. Sufficient scope is therefore offered for discussing the analysis, when these metals are present, in a separate paper, which I hope to contribute at a future date.I am fully aware that this method is far from being perfect. No doubt many, modifications and improvements will suggest themselves to my readers, and I trust that this paper will be the means of giving a certain impetus to the study of Proximate Analysis which at the present time is practically dormant. For the benefit of my readers who are not initiated into the details of ordinary estimations, I have briefly described well known methods, which, however, will be found fully described in most text-books of analysis. Assuming that the ore contains. sulphates and chlorides of soda and magnesia, sulphates, sulphides, chlorides and oxides of copper, lead, iron, zinc, manganese and silver chloride, the analysis would be conducted as follows. The first compounds to estimate are the chlorides and sulphates of soda and magnesia.

Jan 1, 1901

By Richard P. Graff

Author?s note: Diversity in practice exists in the application of Generally Accepted Accounting Principles (GAAP) for purchase price allocations with respect to the recognition of Value Beyond Proven and Probable Reserves or VBPP, as defined by the Emerging Issues Task Force (EITF) in EITF 04-3: ?Mining Assets: Impairment and Business Combinations?. This diversity appears to arise from differing interpretations of what constitutes sufficient information to value components of VBPP in business combinations. Concerned with this diversity in practice, respected members of the mining community formed a working group which prepared an issues paper that discussed this diversity and provided recommendations for recognition and valuation of VBPP in business combinations. The working group then submitted this paper to the EITF, requesting further guidance be issued on the concept of VBPP. In conjunction with the submission to the EITF, the working group also provided this paper to the United States Securities and Exchange Commission (SEC) for review and comment. The EITF discussed this issue at its May, 2008 agenda committee meeting. However, it declined to add this topic to the EITF agenda for further consideration. Absent additional guidance on VBPP from the EITF, the working group submitted a proposed definition of VBPP to the U.S. Securities and Exchange Commission for its consideration. The following article, which is consistent with the issues paper that was submitted to the EITF and the SEC, discusses the components of and valuation techniques for VBPP. The correspondence with the U.S. Securities and Exchange Commission, which includes the proposed definition of VBPP by the working group, is attached as Appendix 1 to this article.

Jan 1, 2008

By K. G. Kebkal, R. Bannasch

"Because the operation of tethered underwater vehicles in the deep ocean or under drifting ice areas is very complicated or impossible, the application of autonomous underwater vehicles (AUV) is preferred or even the only possible solution. However, this implies the possibility of a direct and real-time control over all AUV functions, which is only achievable with the availability of accurate positioning/navigation and a high-speed communication link. This paper presents a flexible bottom- or surface-based solution enabling high positioning accuracy of underwater objects (harvester, AUVs, bottom nodes); specifically, a multifunctional system that combines Ultra Short Baseline (USBL) transceivers and Long BaseLine (LBL) stations deployed at a large depth. Moreover, each baseline transponder is equipped with a high-speed communication device to provide the means for real-time AUV control based on the information about its current position, e.g. navigate it with direct commands and operating its actuators and other mechanisms. Moreover a communication link with a high data rate can provide valuable visual information from the operation area.Depending on how many nodes the LBL grid comprise has, target transponder positions can be estimated with an accuracy of several to tens of centimetres. The purpose of the paper is to present the experiments with all key elements of the multifunctional Hydro-Acoustic USBL-aided LBL Positioning and Communication System."

Sep 1, 2014