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By O`Donnell. P. J.

THE modern coal cutter is a highly developed, and to a certain extent a somewhat complicated, machine. The requisite power to cope with conditions as found must be generated by the motor with due regard to limitations in the matter of dimensions and weight. This imposes the necessity of relatively high speeds of rotation. Any factor external to the machine proper which tends to reduce the load on the motor and gearing is most important. Experience has proved that close attention to the question of cutter-chain details undoubtedly results, in practically every coal-cutting operation, in increased efficiency and reduction of power and maintenance costs. The chain is the unit of the coal cutter which most greatly affects the economical operation of the machine, and only by due consideration of conditions and by the proper selection of the right chain can best results be expected; also, intelligent care of the chain while in operation is essential if it is to give its best service. The chain is the part of the machine that carries the pick boxes or blocks, which are connected to each other by a pair of chain links. The power to drive the chain is trans-mitted by a sprocket. The chain runs in guides supported by a rigid member called a 'jib'. Figure 1 shows the various parts mentioned. The first requirement of a chain is that it cut the coal as fast as possible. The second is that it do so economically. Economy of cutting can conveniently be divided as follows: (1) Economy in power used. (2) Economy in pick life. (3) Economy ' in chain life. ( 4) Economy in jib life. (5) Economy in labour for maintenance.

Jan 1, 1936

By D. M. Muir

The mineralogy of residues formed during the pressure acid leaching of arid region nickel laterite ore varies according to the salinity of the process water, alkali cation additives and the overall acid loading. In fresh water, hematite is the main iron-bearing leach residue component, together with amorphous silica and hydronium or sodium alunite/jarosite [(H3O,Na)(Fe,Al)3(SO4)2(OH)6]. As the process water salinity increases, or as NH4+ or K salts are added, alunite/jarosite is the kinetically favoured iron-bearing phase accompanied by an increase in acid consumption. The alunite/jarosite appears as two XRD distinct phases with different Fe:Al molar ratios. In weakly saline water, iron-rich alunite/jarosite slowly transforms to hematite and an aluminium-rich alunite/jarosite together with the release of acid. The addition of potassium salts forms a more stable alunite/jarosite whilst the addition of ammonium salts leads to greater transformation of alunite/jarosite at 250°C. Weakly saline process water gives enhanced nickel recoveries, whilst strongly saline process water gives lower nickel recoveries but higher soluble iron because of chloro-complexation. SEM and microprobe analysis shows very little nickel is associated with the alunite/jarosite and hematite phases. Nickel losses to the residues are attributed to adsorption on amorphous silica and to a lesser extent on alunite/jarosite.

Jan 1, 2006

By W. F. Baker

Location and History God's lake is in the northeastern part of Manitoba, about 400 miles northeast of Winnipeg, or about 250 miles due north of Red lake, Ontario. The lake is quite large, having an overall length of 54 miles and a maximum width of 18 miles. There are numerous islands in the lake, the largest of these, known as Elk island, being about 15 miles long and 3 miles wide in the widest part. The accompanying map (Figure 1) shows the location of God's lake and of the mine. The God's Lake area has long been regarded as promising country for the prospector, but, due to its inaccessibility, practically no prospecting was done prior to 1927. In the years 1927-1931, inclusive, a few prospectors visited the area, but no discoveries were made. In 1932, Bob Jowsey and Archie McDonald entered the area from Island lake. They first prospected in the vicinity of Knife lake, which is immediately south of the main part of God's lake, and then moved on to the latter lake, heading for the north shore of Elk island. The first afternoon on God's Lake, when looking for a place to camp on the north shore of what is now known as Jowsey island, Jowsey discovered a quartz porphyry dyke which was cut by a number of gold-bearing bluish quartz stringers. On the strength of this discovery, he and McDonald began at once to stake the Reno group of claims. Rumours of the discovery brought in other prospectors, and other groups of claims were staked to the east, along the north shore of Elk island. A second discovery was soon made by Dan McCrea on his Gold Standard claims, three and a half miles to the east of the original discovery. Staking still continued to the east, along the north shore of Elk island, and Bob Brown and Harvey McKenzie staked the Akers group on a discovery approximately two miles east of McCrea's discovery. Through the efforts of Jowsey, the Reno, Rand, Elk, and Cona groups, belonging to the original syndicate for which Jowsey and McDonald staked, were combined with the Gold Standard, Greenstone, and Akers groups, and the Company known as God's Lake Gold Mines, Limited, was formed. Several additional groups of claims were later taken over by the Company and a considerable area of adjoining ground was staked to round-out the property.

Jan 1, 1935

By Gheorghe Marin, Franco Chiesa, David Levasseur, Bernard Duchesne

Over the past 20 years, pressure die casting has evolved to a point where structural parts can now be produced by this process. This has been made possible by the development of vacuum die casting and by the development of die-castable, low iron content alloys. This resulted in the production of low porosity, weldable die-cast parts on which heat treatment may be applied. In the present paper, the influence porosities on the tensile properties of as-cast A360 tensile test bars was evaluated. This was done by casting 24 clusters, comprising three 6mm diameter test bars each, in a 280T cold chamber pressure die casting machine after a steady dynamic equilibrium had been reached. Modeling of filling allowed to explain the differences in porosity observed in the 3 samples of a same cluster while the results of solidification modeling were related to the microstructure. Tensile samples were radiographed on a real time X-cube apparatus and separated into 2 lots: samples where no porosity defect were visible and samples with visible defects. By measuring the tensile properties of the 2 lots it was possible to quantify the drop in tensile properties brought about by porosity, which is the most common defect observed in pressure die-cast parts.

Jan 1, 2015

Accurate hematite solubility data are required to construct predictive solution chemistry models for complex hydrometallurgical solutions. These data are useful in understanding Fe(III) speciation and precipitation in a variety of hydrometallurgical processes. Hematite solubility data were generated in 10 to 70 g/L H2SO4 solutions and at temperatures from 130 to 270°C, using specially modified titanium autoclaves. These measurements represent an improvement over previous experimental data because of better in-situ filtration of the sample aliquots, the approach to equilibrium via hematite dissolution, and the inhibition of Fe(III) reduction on titanium surfaces. Fe(III) reduction was particularly studied to evaluate the inflationary effect of Fe(II) on hematite solubility measurements. Chromate was found to reliably inhibit Fe(III) reduction on titanium. Finally, the generated hematite solubility data were used to construct a solution chemistry model using the OLI software.

Jan 1, 2006

By A. Brian Hawkins

"When pyrite oxidizes in dark grey/black, calcareous, mudrocks or in argillaceous limestones, ferrous sulfate is formed and sulfuric acid is released. The sulfuric acid combines with the calcite present in the rock and calcium sulfate (gypsum) develops. When this occurs on the outer edges of aggregate particles, the gypsum forms in the matrix hence there may be little expansion of the general material. However, when the chemical reactions occur within the rock fragments, particularly on microscopic, clayrich, laminae, the developing crystals exert a significant pressure on the host material. If the rock is medium strong to strong, the force of crystallization splits the rock along the weaker planes, facilitating the ingress of the oxidizing agents and the continuation of the chemical reactions. In addition to causing dilation/heave, some of the engineering properties of the material are changed, including the strength, Los Angeles value, water absorption etc. As a consequence material, which at the time of quarrying would be acceptable for use beneath floors or hardstandings, would no longer be considered suitable.INTRODUCTIONMudrocks accreting in aerobic environments are frequently disturbed by organisms and as a consequence there is often little sign of bedding. In contrast, sediments which have formed in anoxic environments commonly have distinct bedding planes which, because of the grain size of the accreting material, are often smooth and planar. These rocks are frequently referred to as shales, which O’Brien and Slatt (1990) define as “characterised by a finely laminated structure, which imparts a fissility approximately parallel to the bedding.” This should not be confused with rhythmic bedding where the variation in grain size results in lithological laminations or colour changes.Early geologists, in the stratigraphic naming of rocks, often used the term shale for material which is now more likely to be described as mudstone or mudrock (Hawkins and Pinches, 1992). In many contexts, the width of the bedding is an important factor, not only in determining the rock name but also in indicating the potential engineering characteristics. Until recently a shale was considered to have bedding separations of less than 20mm, i.e. the bedding was described as laminated. However, in an engineering context, EN 14689: 2003, Annex A, defines shale by specifying a bedding thickness of < 6mm; such a material would be described as thinly laminated in BS 5930:1999. Ideally the term shale should be abandoned and be replaced by fissile mudstone or fissile mudrock."

Jan 1, 2015

By N. Shi, T. G. Joseph

ABSTRACTA series of algorithms were developed to perform geometric and kinematic analyses of cable shovel dipper-ground interactions for a given set of mining face conditions. The routines examine and analyze (a) the position of the dipper in relation to the shovel; (b) the dipper in relation to the face conditions; (c) the dipper position in relation to possible interference or collision with crawler tracks during digging cycles; and (d) kinematic and geometric considerations with respect to any point on the dip-per as it conducts a duty cycle. In all cases, field measurement verifcation provided good agreement(within 4% variance).

Jan 1, 2011

By Fazel G. Jahromi, Ahmad Ghahremaninezhad

Enargite (Cu3AsS4) is a major complex copper mineral and often is a carrier of invisible gold particles. Pyrometallurgical treatment of enargite is challenging due to the arsenic release to the environment. Hydrometallurgical treatment, on the other hand, appears to be a promising alternative for enargite processing. In an atmospheric enargite leaching process both the copper and arsenic from the mineral can be leached into a sulphuric acid solution and the arsenic can be simultaneously precipitated as ferric arsenate. The unlocked gold in the residue then can be recovered in a subsequent cyanidation circuit. The downside of the atmospheric enargite leaching in sulphate solutions is the slow leaching kinetics. In this study the effective parameters of the atmospheric enargite leaching process in ferric chloride media were investigated. All the experiments were carried out at temperatures below 100 °C. The process parameters that were investigated in this study included ferric, chloride, sulphate and cuprous concentrations, temperature, mixing rate and leaching slurry pulp density. It was found that the copper recovery rate increases with the addition of cupric chloride and also with raising the temperature. The highest leaching kinetics and the highest overall copper recoveries were achieved when cupric was initially added to the leach solution and at 90 ºC.

Jan 1, 2015

By G. S. Hume

In the transformation of carbonaceous materials, such as peat, to coals of various grades, the changes are known to be both physical and chemical and the grade of coal finally produced depends on the stage to which alteration proceeded. Those changes, which are frequently spoken of as the results of metamorphism, are due to pressure with accompanying heat and, according to the amount of metamorphism to which the sediments with the included carbonaceous beds have been subjected, there is a gradation from peat to anthracite coal, and even to graphite. The improvement in the quality of the coal as a result of metamorphism is due to an increase of the carbon content of the coal and a corresponding loss of the volatile materials. This rise in the quality of the coal according to the degree of metamorphism is well illustrated by the coals of western Canada. In the Plains area, where the deformation and the attendant metamorphism of the sediments is comparatively small, the coals are lignites, whereas in the mountains, where deformation has been severe, the coals are semi-anthracites. Sub-bituminous and bituminous coals occur in the intervening areas. The same general relationship between the quality of the coal and the degree of metamorphism holds true for the Appalachian basin of the United States, where there is a progressive improvement in the quality of the coals from west to east, that is, from an area of comparatively slight metamorphism to an area of marked deformation in the Appalachian Mountain region. But while it is true that this relationship holds in a general way, it has been found that the improvement in the quality of the coal is not always uniformly progressive, and there may be local variations such that an area containing coal with a carbon content indicating low or medium metamorphism may be surrounded by areas in which the coals are of higher grade. These local variations in many cases can be explained, and they in no way detract from the general rule that, in a region exhibiting a progressive betterment in the quality of the coal from an area of low metamorphism to one of more marked deformation, the quality of the coal, i.e., the amount of fixed carbon in the coal, may be taken as an index of the degree of metamorphism of the coal as well as of the sediments in which it occurs, It has been pointed out (&apos;) that certain coals, such as cannels, are unreliable indicators of the varying degree of metamorphism because of the nature of the material from which such coal was derived. Such coals, however, are not known in western Canada and their behaviour need not here be discussed.

Jan 1, 1927

By D. L. Morgan, J. A. Butterfield

"Geological data, production trends and current projects underway suggest that enough molybdenum will be available from more diversified sources to meet the world's growing demands. The growth in molybdenum consumption has been primarily related to its beneficial effects as an alloying agent in steel. This rapid growth has been deliberately fostered by stable prices, adequate supply and application research. The molybdenum industry is now in a process of change which has been seen in several other metals, such as aluminum and nickel. As supply sources have become more diversified, the market has become more competitive. The recent drop in consumption has led to excess production capacity, accumulation of substantial producer inventories and increased market uncertainties. While consumption is expected to increase in the next two to three years, it will take some time to absorb the excess capacity and inventory. The increased proportion of by-product capacity indicates that prices may become more variable. Producer discipline will be required to prevent serious price erosion in times of surplus. Future prices may not continue to increase with inflation. For the longer term, several factors favour the increased consumption of molybdenum. Engineering requirements are becoming more severe and molybdenum alloys can help to meet these changing needs. In addition, consumers can rely on a large and increasing supply of molybdenum. A 7 per cent growth rate in consumption can probably be sustained through the next decade, but new applications and reasonably stable prices will be needed to make this possible."

Jan 1, 1972

By C. J. Hartley

"Scandium oxide can be recovered as a by-product from process streams in a number of chemical and metallurgical plants including TiO2 sulphate pigment, Ni/Co laterite, zirconium oxychloride and uranium operations. The feed materials available for processing can be either mid or end of process streams containing many species in solution. This paper describes the strategies available to limit coextraction of elements into scandium containing streams from TiO2 pigment production and the removal of these elements to deliver high purity scandium oxide.A critical part of process development is to work within the constraints of the main process in terms of introducing new unit processes and producing minimal additional process intermediates and residues. This requires flexibility in designing flowsheets and plants to find novel process routes that avoid production of intermediates and/or the introduction of reagents that can compromise the main process operations.Bloom Energy has developed novel solvent extraction processes for the extraction and refining of scandium oxide that minimise impacts on core process streams within TiO2 pigment plants. The additional unit processes are designed to have minimal contact with pigment plant process streams to produce a concentrate that is refined to nominal 3N purity scandium oxide in a simple, small scale commercial plant."

Jan 1, 2016

By N. F. Faria, F. Monteiro, B. O. Taiwo, A. Palangio, D. Fonseca, J. Manuel

This paper explores the interpretation and application of Particle Size Distribution (PSD) curves in optimizing blast design and enhancing downstream operations. The study looks at important factors like D50, D80, fines content, and the uniformity index to show how PSD curves affect the efficiency of different mining processes. The first section of this paper discusses the impact of blast design parameters such as burden, spacing, and explosive energy on the resulting PSD, highlighting their significance for downstream operations like crushing, and material handling. The section concluded that proper alignment of PSD with downstream size classes, like primary crusher inlet sizes, among others, can result in substantial cost reductions and productivity gains. The second part presents a case study from dstgroup aggregate quarry in northern Portugal, utilizing fragmentation analysis to evaluate blast performance and promote continuous improvement. The section specifically examines the effect of stemming material size on blast fragmentation, comparing the impact of using aggregate with a D80 of 12.32 mm versus a D80 of 21.94 mm. The D80 value represents the particle size at which 80% of the stemming material is smaller, making it a critical parameter in evaluating the stemming's effectiveness in confining explosive energy. The drilling and blasting designs were meticulously planned using O-PitDev and O-PitSurface software to ensure accuracy in blast parameters and layout. To assess the fragmentation resulting from these different stemming material sizes, the study utilized WipFrag 4 software. The software allowed for precise measurement of particle size distribution after the blast, as well as a detailed comparison between the two stemming sizes. Results from the analysis indicate that using bigger-sized stemming material led to improved blast confinement, which in turn resulted in better fragmentation compared to the smaller-sized material. The reviewed blast videos demonstrate that the larger aggregate effectively contained the explosive energy within the borehole, thereby reducing premature venting and directing more energy towards breaking the surrounding rock mass. This led to finer fragmentation with D80 = 1240.1 mm, D50 = 685.9, and Dmax = 2580 mm, which is advantageous in downstream operations like crushing and milling. On the other hand, the smaller stemming material (D80 = 21.94 mm) did not confine the explosive energy as efficiently, resulting in coarser fragmentation (D80 = 1327.37 mm, D50 = 750.76, and Dmax = 2370 mm) and reduced overall blast efficiency. These findings highlight the significant influence of stemming material size on blast performance and fragmentation outcomes. 

May 4, 2025

By O. C. Rojas, J. Sanhueza, J. C. Vargas

Empresa Nacional de Minería (ENAMI) is dedicated to the promotion of small and mid scale Chilean mining industry. Paipote, ENAMI Copper Smelter, processes a variety of mineral products as the result of this promotion. The mineral products characterize a wide variation of copper, iron, sulfur and precious metals content as well as the significant dispersion in the content of impurities, such as arsenic, antimony and bismuth. The Smelter Modernization Program, initiated in1997, introduced a series of technological and operational changes. The development of operational planning and control strategies was necessary to optimize the blending of a wide variety of concentrates and the control of metallurgical processes in order to ensure the stable operation, fulfillment of environmental regulations and the quality of produced copper anodes. A permanent optimization process carried out in the last decade led to the permanent increase of the smelting capacity and the production of anodes and sulfuric acid. Additionally, introduced improvements affected the smelter efficiency and metallurgical recovery, demonstrating the possibilities of the optimization of a small smelting facility reflected in good metallurgical and economic results. This paper presents the smelter evolution, introduced technological and process control changes as well as incorporated new reactors and equipment as a continuous process of optimization.

Jan 1, 2007

By Richard J. Wardle, Ambrose F. Howse

The industrial minerals industry in Newfoundland and Labrador is a significant contributor to the provincial economy. The variety ofcommodities produced reflects the diverse geological environment from which they come. A highlight of the past decade has been the continuing development of dimension stone quarries, with producers now active in anorthosite, gabbro, granite and sandstone. Other dimension stone prospects have been identified and are in various stages of assessment and development. Western Newfoundland hosts a large resource of limestone, dolomite and marble. It provides raw material for industries that produce Portland cement, agricultural limestone and aggregate, as well as chemical-grade limestone and dolomite products. In western Labrador, dolomitic marble is quarried for use in the production of self-fluxing iron ore pellets. The recent opening of a new gypsum quarry at Fischells Brook signalled the beginning of a new era in the commercial production ofgypsum, a commodity which the province has produced since the 1950s. Hopefully it will emulate the nearby Flat Bay Quarry (now closed) which was a long-time exporter to markets along the U.S. eastern seaboard, in addition to supplying local demands. Oil production and continuing exploration in the Newfoundland offshore has renewed interest in local barite deposits for potential use in drilling fluids. Already there has been some production from the Collier Point deposit, and at Buchans, an existing plant is being refurbished to recover barite from a large tailings pond. Emerging new industries include the development of an antimony mine in central Newfoundland, the development of silica deposits near Labrador City for silicon metal production, and reactivation of the St. Lawrence fluorspar mine. The province has many deposits with development potential such as rare metals at Strange Lake, white marble at Roddickton and salt deposits near St. George's Bay region.

Jan 1, 2001

By P. D. Barrette

This paper deals with the flow of granular materials in bins. A hybrid Lagrangian-Eulerian numerical model is introduced. The model is based on Particle-In-Cell (PIC) advection, and continuum equations describing a Mohr-Coulomb criterion. Experiments were conducted to test and verify the performance of the numerical model. Tests were done using three types of particles. Measurements of material properties and flow rates were carried out. Video records were also obtained and used to examine flow patterns. The results indicate that the numerical simulations produce deformation patterns and flow rates which are in good agreement with the experimental observations.

May 1, 2007

By Trevor R. Ellis

"The valuation of mineral properties in the U.S. is only partially regulated. The regulations which have jurisdiction or impact appear to have such mainly as a consequence of unintended fallout, since the regulations were designed for other purposes. Court case history can also be important. The combined results are a mixture of bad and good, with important lessons to be learned.Since 1981, the Securities and Exchange Commission has prohibited U.S. listed companies from reporting quantitative estimates of mineralization and the value of mineralization, other than proven and probable reserves. This results in the minerals appraiser (valuator) working with a shortage of data in his everyday work, both on the subject property and in sales analysis.Between 1989 and 1995, all 50 states and essentially all Federal agencies adopted the Uniform Standards of Professional Appraisal Practice (USPAP) for real property appraisals (valuations). The major national appraisal societies also require their members to abide by USPAP. A significant portion of minerals appraisals must now follow these standards. This paper will discuss the content of USPAP. It provides a very good framework for the valuation of a minerals property or a mine, both as real property and as a business. However, the credentialing standards for real property appraisers are now prohibitive for minerals appraisers."

Jan 1, 2003

By Dave Ecobichon, Éric Côté, Simon Nickson, Michel Leclerc

The feasibility assessment of a mineral deposit requires the construction of a geo mechanical model of rock mass properties, for the purpose of preliminary mine design. The Noranda Technology Centre has been involved in the development of geomechanical models for several mineral deposits at the feasibility stage. Each model is constructed through intact rock testing, geotechnical core logging, geotechnical mapping and rock mass classification. Rock mechanics principles are used to develop conceptual stope designs and propose possible mining sequences. This methodology is applicable to both new mining projects and to the development of new areas within anoperating mine. This paper explains how the geomechanical model is developed and reviews its application to several case studies.

Jan 1, 1996

By R. W. Culley

"In many areas of Saskatchewan, known gravel deposits have been depleted or are diminishing rapidly; in other areas, particularly in the north, demands for all-weather highways and access roads are far exceeding the supply of gravel sources with which to surface them. These two problems have made conventional methods of air-photo and ground surveys insufficient for gravel location. In the first case, hauling costs on construction now warrant searching for buried deposits and for smaller, less obvious surficial deposits that may be closer to the project. In the second case, search and access conditions are so difficult and costly that the ratio of successes to failures must be kept very high. The Department of Highways has long been aware of the oncoming scarcity of quality gravel deposits and is continually investigating ways of forestalling it. One of these ways is the use of airborne geophysical methods that permit rapid coverage of large areas and that sense and discriminate between earth properties to a significant depth below ground surface. In 1967, the Department began an investigation of an airborne conductivity survey method called INPUT*, or ""Induced Pulse Transient'', leading to a trial in 1968 and data analysis in 1969. The results of this trial initiated• modifications to the technique to improve its sensitivity for mapping shallow deposits. Part way through this modification in 1970, a decision was made to change to an airborne resistivity survey method called EPHASE*. Trials with this technique were conducted and analysed in 1971. This paper is an explanation of the E-PHASE system and a summary of the results from one of three areas mapped in 1971."

Jan 1, 1973

By P. D. S. St. Pierre

IN REGENT YEARS, blast furnace operators have found it necessary to improve their technology in order to handle increasingly low-grade feed and yet satisfy the demands for greater tonnages of metal. Studies have been made covering several aspects of the problem, and in this connection the slags produced in the iron-making process have been critically examined with a view to discovering the slag with the optimum properties for a given operation. A good slag should combine, as far as possible, the properties listed in Table I. Unfortunately, some of these desirable properties are incompatible. For example, the advantage of the small ?bulk of a low-flux slag is offset by its low desulphurization potential and high viscosity. Similarly, a very fluid slag increases refractory wear. It will be seen, then, that a balance must he struck between these conflicting requirements. In the .present paper only the melting relationships of blast furnace slag ?compositions will be considered in detail. In interpreting the data herein presented, the optimum property requirements listed in Table 1 must strictly be borne in mind. It should also be noted that the discussion presented here always relates to calcined fluxes, since this facilitates reference to the final slag composition. Thus, in making calculations pertaining to the ?burdening of the furnace, due allowance should ?be made for the fact that the fluxes are added as carbonates.

Jan 1, 1956

By F. A. Auld

"Traditionally deep shaft sinking from the ground surface was carried out using drill and blast methods. Although large diameter blind shaft drilling has been carried out successfully on numerous occasions previously, including as early as 1852 in Germany (Auld, 1995), little attempt has been made until more recently to mechanise the shaft sinking excavation process using down-the-hole machines. This paper reviews the development of deep shaft sinking machines from the early 1970’s up to the present day. INTRODUCTION Mechanical excavation methods can significantly improve excavation performance, in order to access natural resources faster, and labour safety is increased compared to drill and blast operations. However, shaft sinking machines need to be capable of accommodating all the basic requirements for deep shaft sinking, namely: 1. Excavation and muck removal 2. Ground stability control 3. Groundwater ingress control 4. Temporary lining installation 5. Permanent lining installation and watertight sealing 6. Ventilation 7. Secondary means of egress for personnel In addition, how the machine operates in the shaft is an important factor, either slung on ropes from a surface headgear or on its own in the bottom of the shaft. An all-embracing machine which can deal with all of the above conditions is impossible but many of these requirements can be incorporated into a single machine. Deep shaft sinking also differs greatly from normal tunnel construction which employs the use of either a roadheader arm installed within a shield or a full-face tunnelling machine for excavation. Hydrostatic pressure and ground stability problems increase with depth, whereas in tunnelling the depth is normally relatively shallow and the aforementioned factors remain approximately constant along the tunnel length. DEEP SHAFT SINKING MACHINES All the shaft sinking carried out previously in the UK was by the traditional method of drill and blast. Elsewhere, in other parts of the world, attempts have been made to mechanise the process."

Jan 1, 2019