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By Christoph Schulte-Schrepping, Bou-Young Youn, Rolf Breitenbücher

"The main requirements of two-component grouts are a high workability and sufficient stability against sedimentation with a retention time of more than 72 hours, as well as a rapid strength development im-mediately after grouting. Component A usually consists of OPC, water, bentonite, and retarding agent. Component B, a liquid accelerator, is added to Component A during grouting at the end of the shield tail. Current investigations on different compositions of Component A showed a high workability lasting for at least 72 hours. The workability could be extended with increasing amount of the retarding agent to a certain degree. An increase of the bentonite content improved the stability of the mix, but had a negative impact on the flowability respectively the workability of Component A. High compressive strengths could be rather achieved by an adapted mixing ratio of Component A and B than by increasing the amount of the accelerator. Thereby, the interactions and compatibility of the selected constituents play an essential role. INTRODUCTION In mechanized tunneling with segment linings, the annular gap between segment ring and soil must be filled instantaneously with an adequate grouting mortar. The main functions of the annular gap grouting are to stabilize the tunnel lining and to minimize settlements of the ground surface at the same time. Thereby, two contradictory requirements are demanded on annular gap grouts: On the one hand a high workability and sufficient stability against sedimentation, on the other hand a rapid strength develop-ment immediately after grouting. Besides single-component grouts, which achieve the necessary stiffen-ing by dewatering into the surrounding soil, two-component grouts are used, especially in cohesive soils with a very low permeability. Basically, annular gap grouts are almost exclusively defined on empirical basis. Fundamental studies about the constituents and composition of the grout as well as the related achievable properties are still missing so far. Therefore, it is necessary to investigate the material-specific correlations regarding the relevant parameters of annular gap grouts – workability and flowability, stability of the mix as well as strength development – in comprehensive experiments. Based on the knowledge gained from the investigations, it should also be possible, to perform the grouting material according to a real design concept and thus, to ensure an adequate grouting in prac-tice considering the geological and hydro-geological conditions."

Jan 1, 2016

By Walter D. Holland

LFE Environmental performed an Industrial Hygiene survey of the Paraho Oil Shale Mining and Processing facility in Anvil Points near Rifle, Colorado, on August 6 and 7, 1975. This survey consisted of an investigation of the underground operations for diesel emission contaminants and of the above ground work areas for all inhalation contaminants other than silica dust. Samples were collected to investigate the following contaminants: respirable dust, total dust, NO2, NO, H2SO4, formaldehyde, CO2, S02 and CO. None of the determinations of contaminants in the underground operations indicate air concentrations exceeding their standards. The results for the samples collected above ground indicate only one operation where the employee's exposure exceeds the standards. It is a welding operation where the standards for total dust and lead are exceeded. Since the survey the employer has installed an exhaust ventilation system which has significantly reduced the welder's exposure.

Jan 1, 1976

By C. M. K. Boldt

The Bureau of Mines surveyed waste disposal sites at 18 metal and non-metal mines and conducted laboratory and full-scale field tests to de-termine the effects of tailings deposition techniques on physical properties of tailings pond beaches. Survey data included measurements of beach slopes, descriptions of deposition techniques, and measurements of beach physical properties taken at various distances from the point of discharge. Laboratory tests involved depositing two types of tailings, each with different grain-size distributions, into a settling trough and determining the resultant physical properties of settled materials along the length of the beach. Side confinement and the closeness of the water pool to the point of deposition caused the laboratory results to be inconclusive. Full-scale field deposition tests conducted at the tailings pond of a cooperating mine showed that there were similarities in relationships between exit velocities of tailings slurry and physical properties of the settled tailings on the beach.

Jan 1, 1988

By Harpal Parmar

This paper evaluates dynamic methods of pile capacity prediction by comparing their results to static load test results. Dynamic and static pile load test data were assembled from four southeastern states of the U.S. End-of-drive and restrike capacities were evaluated using the Pile Driving Analyzer (PDA) and by wave equation (WEAP) analyses. These were compared to static (Davisson criterion) loads. The best comparison was obtained for restrike PDA results; restrike wave equation analyses values also compared well. The end-of-drive results for both methods-showed relatively poor comparisons. The PDA was recognized as an important tool to measure energy transferred to the pile; this transferred energy was recognized as an uncertainty when conducting wave equation analyses. A statistical analysis showed restrike capacity results to be associated with higher precision and accuracy as compared to end-of-drive methods. The authors believe that restrike dynamic testing is essential to establish long term static soil strength and that it will lead to accurate and cost-effective design of piles.

Jan 1, 1996

By Lutz Rolf, Halit Z. Kuyumcu, Salas Cazón. Milton A.

Aim of experimental investigations was the mathematical description of the abrasion process running with a single particle stress. This is on the one hand the basis for the physical interpretation of the process, on the other hand the base for the simulation of abrasion processes carried out in technical scale. With this investigation for the first time the influence of the particle shape changing with increasing abrasion progress was quantitatively described. This influence affects itself particularly strongly on break-fresh particles up to an abrasion degree of approximately 10 to 20%. This is for the description of technical processes the most interesting area.

Jan 1, 2003

By J A. Rowland

When executing a ventilation change the mine ventilation circuit is in a state of flux throughout the entire change period with discrete mine areas both under ventilated and/or over ventilated during the change process. Whilst routine risk reduction strategies such as removing electrical power and people from the mine are commonly deployed it is wise to complete the change in the shortest practical time frame. This not only minimises the chance of unacceptable concentrations of contaminants accumulating around the mine but reduces the impedance on production activities which are routinely suspended during these change periods. This paper firstly highlights the importance of the maintenance of an accurate ventilation model and discusses issues which should be considered to assist to maintain in it a suitable state of health. Further it provides some tips on how to monitor that your model is in an acceptable state of tune so that it can be confidently deployed in the change process. Finally, it details the sequential process how a finely tuned and accurate ventilation model can be utilised to carry out major ventilation changes according to appliance pressure adjustments only and without the need to constantly measure and check resultant branch flows throughout the whole change process. Also discussed are some simple practical tips which will help ensure that the ventilation change process will go according to the devised plan on the day and in the most appropriate order including checking the efficiency and accuracy of the change, after it is completed.

Oct 12, 2022

By Rick Piovesan, Pramod Rao, Nihal Bohra, Mark Wahler

"This paper discusses the approach followed for the geotechnical design of 355 mm and 457 mm diameter driven open-ended steel pipe piles used for a gas plant at a green field site in Pilbara region in Australia. The principal bearing layer at the site comprises of calcareous Red Bed soils and weak rock, which is the typical geology along a significant length of the northern Western Australian coastline with carbonate content up to 70%. The uncertainty associated with the mechanical behavior of the calcareous soils and cemented soils (weak rocks) presented design challenges in the selection of appropriate pile design method and design parameters for pile capacity estimation during Front End Engineering Design (FEED). The American Petroleum Institute (API)-based design methodology was adopted. The representative design parameters for the Red Bed weak rock were established by treating the weak rock as clay with undrained shear strength as one-half of the characteristic unconfined compressive strength (UCS) value. Both statically load tested and CAPWAP (Case Pile Analysis Wave Program) estimated ultimate axial pile capacities on 25 early pre-production indicator piles demonstrated that the API design methodology for siliceous soils provides reasonable prediction of axial pile capacity in the red bed soils/weak rock and no reduction to API computed axial capacity due to carbonate content is warranted. The results also demonstrated that penalizing axial pile capacity solely based on carbonate content is not appropriate.IntroductionA gas processing facility was proposed to commercialize the gas reserves located 130 km offshore from the north-west coast of Western Australia (WA). The project site is a green field site located in the Pilbara region along the northwest coast of WA. Specific information regarding the site has been withheld due to confidentiality reasons. The site layout is shown in Figure 1.The site comprises low-lying tidal flats, clay pans and sand dunes covered with low scrub. The onshore site levels vary from elevation 1 m to 10 m AHD (Australian Height Datum), with the largest proportion of the area (excluding sand dunes) between elevations of 1 m and 3 m.The onshore facilities are to comprise a liquefied natural gas (LNG) plant site, a construction camp, the land-based portion of the materials offloading facility (MOF), roadways, and borrow pit areas.The existing ground levels within the process train area, where pile load testing was performed, vary from over 7 m AHD where the summits and peaks of the central dune exist to typically 1 m to 2 m AHD towards the east and west edges of the dune. The proposed finished grade for the process train is set at 7 m AHD."

Jan 1, 2015

By J. P. Smith

Permian salt measures carry extensive lenses of soluble potash salts in north central Germany. Potash deposits of Oligocene age are found in the Upper Rhine Graben of Alsace (France), and in the Catalonian Basin of Spain. These deposits are found in a wide range of structural settings. Reserves are large, and the production of potash salts is an important phase in the economy of each of these countries.

Jan 1, 1950

By K. A. Natarajan, S. C. Riemer, I. Iwasaki

The relative significance of corrosive and erosive wear in magnetic taconite grinding is examined. The influence of different types of aeration (nitrogen, air, and oxygen) on ball wear was established for mild steel and high carbon low alloy steel balls. Ball wear data from dry and wet grinding tests are compared with those obtained in the presence of an organic solvent that does not promote electrochemical corrosion. Marked ball grinding tests and electrochemical measurements involving ball material and magnetite electrodes indicate that contribution from oxygen toward wear (corrosive wear) is relatively small, and abrasive wear appears to be significant. Rheological properties of the slurry appear to have an important bearing on the abrasive wear of grinding balls.

Jan 1, 1985

By Vladimir Grujic, Milorad Grujic, Ivan Djurkovic, William Riggs

"In this paper, we have studied efficiency of different chemical structures of frothers on copper ore Majdanpek. The goal was to find out the best suitable chemical structure, which allows good bubble formation, size and interaction, forces on mineral surface. The particle size distribution was between 10 and 100 µm. Our research was oriented on three groups of frothers: alcohols, poly glycol ethers and poly glycols.We also used different collectors based on similar or less similar alcohol group in chemical structure as in frothers, expecting higher stability of air bubble in contact with copper minerals. Minimal potential energy was determinate in the hydrodynamic conditions for different particle sizes. It was founded that it is proportional to air bubble volume on 0.88° and contra proportional to the kinematics viscosity of pulp.Analyzing the results, we find out that poly glycols decreased surface tension the most. Also, it increased amount of coarser particles to the top of pulp. This group is less sensitive to pH value compared to the others too.From the class of frothers with higher efficiency in flotation process, we pointed OrePrep X-75 and X-133 as frothers with expressive frothing characteristic in the alkaline and low alkaline circuits. Special suitability of those frothers for floating copper minerals makes their hetero polar molecules with more than one hydrocarbon radicals connected to one polar group. However, those froters have no nether high or low solubility and are non-ionization. Those froters indicate some small collecting characteristics too. In dispersion systems, those two frothers make two types of bubbles: smaller di < 1.2 mm; V = 0.0008 cm3 and middle di < 16 mm; V = 2.2 cm3 (di – Bubble diameter, V – Bubble volume). Transportation speed of air bubbles it is possible to calculate based on equation: ?s = 27.5 * di 1.4 cm/s. Distribution of free surfaces for chalcopyrite is average 80% in the class –74µm +10µm and 20% in the class -10µm. If we get all class sizes, we find that recovery (R) depends from the time by equation:"

Jan 1, 2003

By J .. A. Nemes, I. Ragai

This paper discusses one of the common problems associated with sheet metal forming processes, which is spring back. The materials presented here, stainless steel 410 and Inconel 718, are commonly used in aerospace applications for their superior material properties. Standard tensile tests were performed to determine their tensile properties, as well as material anisotropy. In addition, the effect of anisotropy on springback was assessed experimentally through simple multiple-bending experiments in different directions to the rolling direction. Finally, draw-bending experiments were carried out to study the effect of forming conditions, such as blank holding force, on the final springback angles of the formed parts. For both materials, it was found that the R-values measured for different sheets exhibited variation. However, the specimen orientation does not have a large effect on material tensile behavior or springback angle for simple bending. For the Inconel 718 specimens, the springback angle slightly increases with each stage of deformation during multiple bend experiments. The effect of the blank holding force on springback angles was also examined and found to have a significant effect on thin specimens.

Jan 1, 2006

By Carlandrea Albonico, Salvatore Miranda

The paper describes an innovative geotechnical engineering solution that has been provided within the scope of the Galataport Project, in Istanbul, Turkey. Among all interesting geotechnical works included in the Project, this paper presents the design principle, adopted technologies and performance controls related to the Multi- Purpose Bottom Plug (MPBP). This original geotechnical engineering solution has been employed for the deep basement excavation in Karaköy and consists of a combination of seepage control, ground improvement, and load bearing elements, which have been executed with double-fluid jet grouting, pseudo-elliptical jet grouting and permanent micropiles, respectively. The paper highlights the importance of employing cutting-edge technologies within the foundation engineering field and state-of-the-art electronic control devices, in parallel with the essential human expertise, in order to obtain the desired results in this high-profile Project.

Nov 1, 2022

By M Carr, C Wheeler, M Lurie, B Chen

The demand for steel products in modern society is prompting the iron ore industry to optimise their operations to ensure sustainability of fines and lump products. One of the key components in the iron ore transportation chain are belt conveyors. The energy consumption of modern belt conveyor systems has reduced considerably over the past few decades, however, there is still significant scope for further reductions, especially when heavily loaded long overland belt conveyors are considered. A new rail based continuous bulk material transportation system has been developed by researchers at the University of Newcastle to reduce the energy consumption of heavily loaded and long overland conveyors. The Rail-Running Belt Conveyor technology is a state-of-the-art continuous belt conveying technology which provides an innovative and novel departure from conventional continuous bulk material transportation systems with significant energy and economic benefits. This paper presents an overview of a Rail-Running Belt Conveyor variant which considers an enclosed belt. Enclosed belt conveying has the benefits of encapsulating the bulk material, and thereby reducing dust emissions and moisture ingress, in addition to being able to negotiate smaller radius horizontal and vertical curves leading to greater flexibility. To quantify the primary differences between conventional conveying technologies, the Denver office of thyssenkrupp Industrial Solutions (USA) developed a case study for an 11 km long conveyor. The conveyor design throughput was 2750 t/h and included a small net elevation loss of 10 m. When considering CAPEX the Rail-Running Pipe Conveyor equipment supply cost is approximately 45 per cent of the cost of a conventional pipe conveyor, while savings upwards of US$50M emerge for CAPEX combined with five years of OPEX. The savings vary with the topography and density of the bulk commodity, with iron ore generally showing increased savings because the high bulk density increases rubber losses in conventional conveyors.

Nov 8, 2021

By Leland A. Yerkes

Refining aluminum from crude aluminum alloys by the subhalide reaction was investigated to develop a method of producing aluminum by means other than electrolysis of its oxide. The best materials and design for the apparatus and also optimum operating conditions, including temperature, pressure, vapor flow rate, and composition of alloy charge were studied. In the subhalide process, aluminum-trihalide vapor reacts with aluminum in the alloy under high temperature and low pressure, forming volatile aluminum monohalide which reverts to aluminum metal and aluminum trihalide on cooling. The only halide used in this investigation was aluminum trichloride. The crude aluminum-silicon alloys used as the principal raw material contained from 21.9 to 36 percent aluminum, and significant quantities of iron and titanium. These alloys were produced by direct electric smelting of clays. Graphite tubing that was heated by an induction coil proved to be satisfactory material for the laboratory reactor chamber, Enclosed in an insulated glass or quartz pipe, the reactor was used in both vertical and horizontal positions with various baffle and tray arrangements for directing the trihalide vapor both over and through the alloy. Aluminum trichloride vapor was generated in the sublimer at one end of the glass pipe, passed into the reactor where contact was made with the crude alloy, and aluminum monochloride gas was formed. When the gaseous mixture of aluminum monochloride and unreacted tri-chloride passed out of the reactor and entered the condenser, the gases were cooled to 900° C. or less, causing the monochloride to disproportionate into aluminum and aluminum trichloride vapor. The aluminum was deposited on the condenser walls while the aluminum trichloride vapor was carried out of the condenser and into the opposite end of the glass pipe where it solidified on the cooled copper coils.

Jan 1, 1961

By A. J. Naldrett

Over the past six or seven years important new ideas have been developed concerning the origin of nickel sulfide deposits. To a large extent these have been stimulated by the major nickel discoveries of the Eastern Goldfields area of Western Australia (Woodall and Travis, 1969; Ewers and Hudson, 1972). Prior to these finds, the most important nickel camps were regarded as being associated exclusively with intrusive rocks such as the Nickel Irruptive at Sudbury or the intrusive peridotites at Thompson, rocks that were thought to have no close association with volcanism. Study of the Australian discoveries, coupled with work in South Africa (Viljoen and Viljoen, 1969) and Canada (Naldrett and Mason, 1968; Pyke, Naldrett and Eckstrand, 1973), has shown that volcanic rocks with true ultramafic compositions and extrusion temperatures of 1400 to 1600°C were a common feature during the Archean. Under certain circumstances economic concentrations of nickel sulfides have formed from these rocks, either settling to the base of their associated flows or accumulating in shallow intrusive feeders to the flows. The aim of this article is to show how these ultramafic rocks can be recognized, how the nickel deposits, if present, are likely to occur within them, and what special features characterize ore-bearing examples of the rocks.

Jan 1, 1975

By E. Morgan Massey

Located in virgin coal acreage near Gilbert, W. Va., Massey Coal Mining Co.&apos;s Ben Creek No. 2 mine afforded the company&apos;s engineers the opportunity of designing and laying out the entire mining operation from the mine faces to the railroading loading site. However, the topography of this region posed difficult problems in haulage of coal for, in this extremely rugged terrain the uppermost coal seams lay in the mountain-top ridges, approximately 1400 ft above the valley floor. The decision for mining equipment naturally leaned to the new high-capacity continuous miners where seam conditions permitted: otherwise, to the new super-high capacity conventional cutting and loading machines. Since the coal seams lay in ridges and points of considerable outcropping, the decision was to keep the transportation on the surface and mine the coal with multiple entries into the outcrop. This way, the major problems of underground haulage, drainage, and ventilation are eliminated, and the opportunity to take advantage of a-c underground power becomes a much simpler proposition.

Jan 10, 1960

By Ramiro da Conceição do Nascimento Júnior

O uso de minérios lateríticos na metalurgia extrativa do níquel tem demandado investimentos em pesquisa e acordos de cooperação técnica para o desenvolvimento de tecnologias mais econômicas e produtivas. Devido às características de difícil processamento do minério e pelo decréscimo da sua quantidade e qualidade, ressalta-se a necessidade de se determinar técnicas efetivas de concentração, que possibilitem o aproveitamento de minérios marginais finos. Estabelece-se então, dentro de uma rota de processamento proposta, a estratégia de se produzir aglomerados (pelotas e/ou briquetes) a partir de concentrado de níquel. Além da fabricação dos aglomerados, faz-se necessária a sua caracterização em uma série de ensaios, para servir de base para a certificação desse produto e sua aplicação em processos de obtenção de ferro níquel ou gusa enriquecido com níquel. Um dos ensaios realizados envolve a caracterização física desses aglomerados. O ensaio foi realizado em máquina universal de ensaios, observando-se a resistência à compressão de amostras de aglomerados que passaram por diferentes tipos de rotas de processamento, e de diferentes etapas do processo de pelotização. Os resultados mostram que os aglomerados submetidos ao ensaio possuem resistência à compressão de pelotas verdes e secas de minério de ferro, conforme o esperado.

Aug 17, 2017

By Q. G. Reynolds, R. T. Jones

"Residence time distributions are well defined for batch and continuously stirred reactors. However, there exist many smelting furnaces that do not fit either of these classifications. A mathematical description is presented for the case of a furnace that is fed continuously, but where the liquid slag and metallic products are tapped intermittently. The effects of slag and metal tapping intervals and the fraction of liquid retained in the furnace, are shown to have a significant effect on the residence time distribution.INTRODUCTIONThere are some processes in which the time spent by the feed material in a smelting furnace plays a significant role in determining the extent of the reactions between metal and slag and influences the degree of settling of metal droplets from a molten slag.Residence time distributions are well defined for batch and continuously stirred reactors. However, there exist many smelting furnaces that do not fit either of these classifications. Here we will focus on producing a mathematical description for the case of a furnace that is fed continuously, but where the liquid slag and metallic products are tapped intermittently. The effects of slag and metal tapping intervals and the fraction of liquid retained in the furnace, are studied.Previous work (Jones, la Grange and Assis, 1997) has studied the effect of retention time on the degree of cobalt recovery achieved in a slag reduction process. In that work, a method was proposed for the calculation of the mean residence time of the contents of a pilot-plant furnace. That approach is to be extended here for the purposes of providing a more general design or scale-up tool.The maximum allowable depth of molten material in a given furnace is affected by such factors as the desired batch size (or the size of the ladles) and the pressure of the molten material that the tap-hole and surrounding system can withstand. Within these constraints, there might be some scope for choice of taphole position. The effects of this choice need to be understood mathematically."

Jan 1, 2012

By Andreas Munko

A Outotec está desenvolvendo em escala piloto o queimador de baixa emissão de NOx desde 2012, resultados expressivos foram atingidos (o pedido de Patente já foi depositado). Em 2014 utilizando simulações CFD, os resultados atingidos em escala piloto foram reproduzidos com boa aderência e os resultados em escala industrial se mostram com os mesmos comportamentos em tendências dos resultados da escala piloto, se mostrando promissores também. O presente trabalho apresenta os passos de desenvolvimento, os promissores resultados e o próximo passo deste desenvolvimento é realizar um teste em escala industrial com o queimador desenvolvido.

Aug 17, 2017

By R. Barbaroux, J. -M. Lalancette, D. Lemieux, K. Nasrallah, G. Garcia Curiel

"Arsenic released from the lithosphere by mining and metallurgical activities is a growing global environmental concern. Dundee sustainable technologies (“DST”) has developed a processing technology to sequester arsenic by means of vitrification. This method can effectively sequester arsenic trioxide without the need to oxidize from As (III) to As (V). Arsenic oxide is incorporated within a silica glass matrix that is stable as per the Toxicity Leaching Characteristic Procedure (“TCLP”) or EPA Method 1311. In this paper, the conventional treatment of arsenopyrite, commonly referred to as “two-stage roasting”, is discussed along with the options traditionally available for the remediation of the arsenic trioxide by-product. The drawbacks limiting the adoption of this processing flowsheet are discussed and a new processing route is presented for the treatment of arsenopyrite. This new flowsheet outputs an auriferous aluminosilicate highly amenable to gold extraction (> 96%) while eliminating the sulfur dioxide production associated with the second-stage roasting of pyrrhotite and ultimately uses vitrification as a definitive sequestration solution to arsenic trioxide.INTRODUCTION Faced with the depletion of conventional gold ores, the gold industry has witnessed a trend towards the exploitation of arsenical deposits. Arsenic is a naturally occurring metalloid often found in mineralogical association with gold. Many northern Canadian regions, from the Northwest Territories to Northern Manitoba, Northern Ontario and the Abitibi region are facing significant arsenic challenges. Projects are deemed uneconomic or prevented from going into operations due to the costs associated with handling arsenic material and there are penalties imposed to complex concentrates by smelters. In addition, Canadian mining operations have left an environmental legacy of gold tailings with grades typically of up to 9 grams per tonne with no processing solution as they also contain significant arsenic contamination at grades of up to 20%. Table 1 presents a list of Canadian deposits known to contain arsenic."

Jan 1, 2017