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By Allen Garrison

IT is the purpose of this article to present. the results of an investiga-tion of certain clay and shale suspensions having viscosities that are materially influenced by fluid motion, and to discuss the bearing of these results, upon the choice of policy in the control of drilling fluids. A previous article described the design and the characteristics of an instru-ment adapted to measure the viscosity of plastic suspensions during continuous uniform motion and at a variety of speeds.1 It has long been recognized that the viscosity of a clay suspension depends on the past history of the fluid motion. Since an abundance of literature is available on this phenomenon,2 it is not necessary to describe it in more than general terms. It is usually observed that rapid motion reduces the viscosity of a clay suspension, and that some time is required for the viscosity to fall to its equilibrium value after the steady motion is started. On reducing the speed of motion to some lower value, the viscosity again rises, but it also requires some time to attain a steady viscosity value at the slower rate of motion. Thus clay suspensions are usually observed to be increasing in viscosity as time passes when the measurement has been immediately preceded by fluid motion that was more rapid than that employed in the measurement. And it is usually observed that the viscosity falls as time passes when the measurement has been preceded by more quiescent conditions. Reed,3 and Broughton and Hand4 have reported a condition of observa-tion of clay suspensions in which the viscosity was observed to fall during the first few moments of steady motion, and rise thereafter. The characteristics of the new instrument are particularly well adapted to studies of this kind. With it we have been able to observe all of the phenomena described above, and it is important to understand their nature because they all occur at some time during normal drill-

Jan 1, 1939

By Robert F. Conley

In the mining, manufacturing and application of inorganic pigments, dispersion contributes significantly. This is especially true with mineral pigments because of the variety, in slurry operations required for their processing. Such operations include any of the following: (1) mine-transport (2) wet grinding (3) flotation/beneficiation (4) wet magnetic separation (5) selective floculation (6) size classification (7) chemical processing (8) spray drying Dosage levels and general economics of dispersant use are broadly variant, being dependant upon the agents employed, from the simplist, i.e., sodium silicate or sodium carbonate, to the more complex, as polyacrylates and organo-phosphates. In certain unit processes the dispersant must exhibit unusual chemical stability and persistence, e.g., in protracted pigment slurry shipments. In others, the agent should be fugitive to prevent secondary reactions from occurring, e.g., with high temperature calcination where alkali salts can act as aggregation fluxing agents.

Jan 1, 1985

By D. M. Evans, D. L. Buchanan

Paper presented at the IAGOD international symposium on mineralisation related to mafic and ultramafic rocks, held in Orleans, France, 1-3 September 1993. The Zinca area was chosen as a suitable location for an investigation of the weathering and secondary dispersion of platinum group metals from the Zone. It was concluded that platinum is immobile while within weathered rock, its mineral phases tending to alter from primary sulphides and tellurides to secondary Pt-Fe alloys. Palladium is variably mobile in weathered rock. In stream sediments Pt occurs mainly as small, dense, discrete particles, giving rise to a nugget effect, whereas Pd probably occurs as much finer particles or chemically adsorbed on to a suitable substrate. Pt shows a rapid decrease in sediments downstream from mineralisation, whereas Pd has a much slower downstream decay

Apr 1, 1994

By Percival T. J

Precious metal deposits containing fine-grained disseminated or dispersed gold-silver form by reactions between metal-bearing hydrothermal fluids and sedimentary host rocks. Host rock permeability and chemical composition exert a primary influence on the fluid movement necessary for any primary dispersion halos to form around ore bodies, and determine whether a disseminated style orebody itself will even form. Where the mineralized rocks are relatively unfractured the margins of the orebodies exhibit abrupt decreases in gold content, and strong corresponding decreases in the contents of other metals. Primary dispersion patterns of this type are difficult to recognize and commonly are only a few meters (or less) in width. If the host rocks were well shattered and broken before mineralization, remnant amounts of the hydrothermal fluids may be dissipated in fractures lateral to or above the ore zones. This causes geochemical anomalies to form with clays and silt- size silica within the fractures over distances of up to at least 30-50 meters away from the main orebodies. The tendency for large primary dispersion halos not to form around these deposits explains the disappointing results from so many drilling programs where no multi-gram gold-grade material was even found: if large areas and apparent large volumes of rock contain one gram or less gold that likely is the "orebody" and not a halo effect around high grade mineralization.

Jan 1, 1988

By Jhon Silva-Castro, Russell Lamont

Understanding the behavior of materials subjected to high strain rate conditions is of fundamental importance to the mining industry. Several stages of the mining process involve high speed loading rates including blasting, scraping, comminution, etc. Technical comprehension of how rocks deform, fracture, and fail under these loads is a fundamental first step required prior to any serious attempts at optimization of the energy utilized for pertinent activities in the mining process. A Split-Hopkinson Pressure Bar (SHPB) was designed and constructed at the University of Kentucky to study the dynamic properties of various types of rocks.

Jan 1, 2017

By J. A. Finch, A. R. Laplante, R. Espinosa-Gomez

"The Niobec concentrator rejects up to /5% of the Nb as slimes (-10u.m). The recovery of Nb from these slimes by column flotation is being studied. An essential condition for selective flotation is slimes dispersion. A particle size analyzer, the Sedigraph 5000D, was used to monitor dispersion in plant waters with combinations of organic and inorganic dispersants and flotation reagents. Flotation reagents were particularly detrimental to dispersion with sodium silicate. The best dispersion conditions were selected for column flotation tests. These tests revealed that reagent combination had a pronounced effect on froth stability. Careful frother selection achieved good froth stability under conditions of good dispersion. Plant water increased the required dispersant concentration causing mineral depression.IntroductionSlimes (-10 u.m) rejected at Niobec contain up to 15070 of the over-all Nb content . Recovery of Nb from these slimes would significantly increase over-all recovery. A suggested recovery route involves two phases: (1) carbonate flotation (to remove most of the carbonates) depressing silicates and pyrochlore (as currently done at Niobec); and (2) selective (direct) pyrochlore flotation from the silicates. Phase 2 has been addressed and several routes to achieve selective flotation are available. Phase I was attempted with the selective reagent scheme used at Niobec but a considerable amount of pyrochlore floated with the carbonates due to poor slimes dispersion."

Jan 1, 1987

[The following notations will be used: O an ore body. z a point in O. z' another point in O. w0 (z) a point support of infinitely small dimensions w0 centred in z. w (z) a sample (or block) of finite dimensions kv centred in z. W (z) a block of size W greater than or equal to w. W'(z) a block of size W' greater than or equal to W. W" (z) a block of size W" greater than or equal to W'. x (z) value of the regionalized variable x with support wO at point z. p (z) average value of x in w (z). pw WZ) = E[x(z')l zt in w(z) pw (z) average value of x in W (z). pwl (z) average value of x in W' (z). pwU (z) average value of x in W" (z). Note that pW (z), pw (z), pwf (z) and pw,, (z) are (regular- ized) regionalized variables with support w, W, W' and W" respectively. The relative sizes of wO, w, W', W" and O are represented schematically in Fig. 7.1. The variance of pw (z) when w (z) takes all possible positions in O is known as the dispersion variance of w in O and is denoted by a? (w in O) or a\: 0; = a2(w in a = Ew,z, inn {[p~ (z) - p121. (7.1) For convenience, the following simpler notation will be used: a> Ew in n [(p w - pl21. Consider now a large block W (z) in O with average value p~(z), and all the possible smaller blocks (or samples) w (z') of size w in W (z). We can calculate the variance of the blocks w (z') in the block W(z), which is the dispersion vaciance of w in W (z), from the relationship a2 [w in W(z)l = Ewcz,, in W(Z) {[PW (z') -pw (z)l21. (7.2) Provided the intrinsic hypothesis is satisfied (§3.4.4), this variance is a function only of the dimensions of the supports w and W, and is independent of the position z of the block W (z). We can therefore define the dispersion variance of w in W, as follows: u2 (win W) = Ew in w [(ptti - PW)~]. (7.3) In cases where the intrinsic hypothesis is not satisfied, the variance of samples w in blocks W may vary only slightly from block to block, so that the average dispersion variance of w in W (z) for all possible W (z) in O can be used: ayw in W) = Ew(,, ~n n {a2 [W in W (z)]}. (7.4) The following example will help to illustrate the importance of the variance of dispersion. Assume that we plan to develop a bedded coal deposit Q. We consider mining the ore body with only one giant dragline, which will extract each day a block of coal of size W'. The total area mined in a year will have a size W". We want to know whether this scheme is acceptable, given that the daily variation in ash content must not exceed a given percentage specified in the sales contract, which is renewable on a yearly basis. On a given day, if we mine the block W' (z), the ash content will average pwT (z). In a period of one year, the expected daily variation in ash content is measured by the expected variance of pwf (z) in W", i.e. by a2 (W'in W"). An alternative mining method might be to use two smaller draglines, each one mining W'/2 of ore per day, and Wn/2 per year. If the draglines are used to mine two distinct sections of the deposit, the expected daily variation in ash content will be u2 (W'/2 in Wj1/2)/2 Other situations, where economic decisions cannot be made without knowledge of the dispersion variance, are illustrated in § 7.4 and 7.5 below. Remark: The notation a2 (w in W) is used in this publication because of its clarity. An alternative notation, which is increasingly accepted in the literature, is s2w/W. ]

Jan 1, 1978

By M. C. Fuerstenau, J. J. Fitzgerald

Aluminum silicate hydrosol synthesis and characterization are discussed. Plausible polymeric aluminosilicate species are presented together with their effect on electrokinetics of selected minerals and flotation response of various ores. The addition of aluminosilicate hydrosol to porphyry and oxide copper ores and to a tungsten ore resulted in enhanced flotation recoveries ranging from about 1.5 to 5 percent. A significant portion of the nation's mineral resources are presently lost in the form of particles with very fine grain size. In the case of copper, for example, approximately 225 million tons of ore are concentrated by flotation per year in the United States. Total losses from porphyry ores are generally 15 to 20 percent with half of these losses being finely-divided copper sulfide minerals which do not respond to flotation. The additional 5 to 10 percent loss is the result of copper oxide minerals which are not floated. The losses of copper sulfide minerals are thought to be due in part to the lack of appropriate dispersion of the finely-divided solids less than 20 microns in size. To effect dispersion in flotation systems, sodium silicate is commonly added. Enhanced dispersion effectiveness is achieved when polyvalent metal salts are combined with sodium silicate. Since originally described by Patek (1), numerous workers have explored the utility of metal silicates. Makrousov (2), Belash et al. (3), and Eigeles (1950) (4) showed the applicability of these reagents to calcite/apatite and fluorite/calcite ores. Mercade (5, 6) reported depression of calcite in the presence of 3.33/1 mole ratio Al/Si hydrosols prepared from Type N sodium silicate (Si02/Na20 ratio 3.22/1) and 1% A12(SO4) 3•18H20 solutions. He importantly observed that the colloidal precipitates did not play a significant role in dispersion and depression but that the soluble species were responsible for this action. Patented work by this author described metal silicates used to depress calcite in scheelite flotation using 1% metal salt (FeSO4•7H2O, CoSO4•7H2O, etc.) and 5% Type N sodium silicate solutions to produce hydrosols with Si/Fe or Si/Co ratios of 8.79/1. Aluminum (III) ion systems were less effective as depressants than the iron and cobalt systems. Yang (8, 9) has studied metal silicate sols for use in the flotation of lithium and ultra-fine hematite ores. Using 10/1 Si/Fe mole ratio hydrosols prepared from 2% ferric nitrate, Fe(NO3)3.9H20, and 5% Type N sodium silicate solutions, solutions, he showed that the hydrosols either modify the slime particle surfaces or are adsorbed on the slime particles preventing anionic collector adsorption. In a subsequent patent, Yang also reported the use of these hydrosols as dispersants for beneficiation of lithium ores. Recent studies of aluminum silicate hydrosols in the flotation of chalcocite, chalcopyrite and scheelite have been reported using Si/Al dispersants prepared from 5% Type N sodium silicate and 0.1 M aluminum chloride (A1C13.6H20) solutions. Dispersant properties were shown to be dependent upon the method of synthesis, supernatant pH, and the hydrosol Si/Al mole ratio. Polymeric soluble species in these hydrosolsupernatants have been proposed as the active dispersant species. Aluminosilicate hydrosols are synthesized by the general reaction scheme presented in Figure 1. Commercial sodium silicates are available with ratios of SiO2 to Na20 of 1.60-3.25. The sample which is most frequently employed is Type N whose ratio of Si02/Na20 is 3.22/1.00. Gel filtration chromatography and NMR studies have shown that these sodium silicates contain numerous species of molecular weight from 325-2,000 gm/mole. Monomeric, oligomeric and higher molecular weight linear polymeric arrangements of these structures are found in these solutions.

Jan 1, 1989

By Éverton Rafael Breitenbach

A liga MA2024, reconhecida pelas aplicações em componentes aeronáuticos e automobilísticos, foi obtida por moagem em moinho atritor. Com o objetivo de melhorar as propriedades mecânicas, adições de 2,5%; 5%; 10% e 20% de reforço com tamanho de partícula inicial menor que 45 µm foi realizada em moinho planetário, com relação de carga:bolas de 3:1 e 15 minutos de moagem a 250 RPM. A consolidação dos corpos de prova cilíndricos foi realizada pela técnica de forjamento de precisão, em matriz fechada em forno tubular na temperatura de 490oC. A microestrutura foi avaliada por microscopia óptica e eletrônica, enquanto que a resistência mecânica foi avaliada por ensaio de microdureza. Os resultados de microscopia revelaram a formação de intermetálicos que influenciam de forma positiva e significativa no comportamento mecânico dos compósitos.

Aug 7, 2018

By Stephen Chung, John Carpenter, Scott Gosch, James Breedlove

While controlling fly rock and ground vibration in quarrying in the neighborhood of a residential area, producing good fragmentation and keeping different grades of material separated in a muckpile are important in maintaining the productivity of quality aggregates. This paper describes a single row production blast for the study of fragmentation and displacement in the grade control carried out at a quarry of Barrett Paving Materials Inc. in Sylvania, Ohio. Digital video imaging was used to monitor the blast-induced motion of the bench face as input to the DMC_Blast (Distinct Motion Code), for the analysis of the formation of the muckpile. The actual digitized blast video and the DMC_Blast simulation are compared. The displacement and mixing of all the inter-bedded limestone layers are made visible in the simulated cross-section of the muckpile. The apparent fragmentation analysed with PowerSieve is also discussed.

Jan 1, 2001

By Lisa M. Splitter

Drilled displacement piles were constructed as the foundation for a proposed 10-story building in San Francisco, California. At the study location, the stratigraphy consists of 14 to 21 feet of fill and 13 to 23 feet of weak, compressible clay (?Bay Mud?), underlain by dense sand, stiff clay, and bedrock. A sensitive critical public utility is located within approximately 20 feet of the constructed piles along one side of the building. The utility pipeline is entirely within the Bay Mud where it is adjacent to the project site. The San Francisco Public Utilities Commission (SFPUC) developed limits on the allowable total and differential movement of the utility pipeline. As requested by the SFPUC, inclinometers and piezometers were installed to monitor the soil movement and pore pressure increases in the Bay Mud caused by the installation of drilled displacement piles. Action levels were set such that if displacement and/or pore pressures reached an action level, the installation methodology would be reevaluated and additional measures to reduce these effects would be implemented. This paper will present the sequence of pile installation near the pipeline and monitoring points, and the data collected from inclinometers and piezometers at variable depths and distances from the piles. The data will highlight the build-up and dissipation of pore pressures over time and the displacement of Bay Mud caused by the pile installation. The conclusions of the study are useful in determining sequencing, spacing, predrilling, and other measures that can be implemented to decrease the displacement potential and pore pressure build-up in soft clays.

Jan 1, 2009

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

In open-pit mining operations, the presence of remnants from past underground labors represents a significant operational challenge, especially if they are in the surroundings of high-grade zones. The existence of uncrushable elements, such as metallic support fragments of abandoned equipment, can trigger critical operational issues if they reach conveyor belts systems or primary crushers, jeopardizing the mine to plant operational continuity. These kinds of incidents lead to expensive unplanned shutdowns, the increasing of corrective maintenance events costs, and risk to meeting expected production results. This work demonstrates the application of a three-dimensional numerical modeling tool for simulating rock displacement post-blasting (by integrating key design parameters, such as blast pattern design, detonating times, charge distribution and pre and post blast surveying). The study was conducted at Andina Mine, operated by Codelco, Chile, and enabled the identification and zoning of areas with potential presence of underground hazards in displaced rock mass, using historical data from previous workings and geotechnical mapping. The displacement results were compared to the actual post-blast surveying, ensuring an acceptability level above 80%, considering both fully confined (bank opening) and free-face blasts. Additionally, this approach allows the determination of an optimal safety offset, initially set at 10 meters and currently under validation for potential reduction. The results supported the determination of safe extraction zones and the design of excavation, loading, and haulage strategies from mine to plant or stockpile, ensuring 100% reliability in the segregation of high risk materials. Implementing displacement simulations underscores their relevance in operational risk prevention and mitigation, adding value to short-term mine planning and strengthening the safety, efficiency and profitability of the open-pit mining production process.

Jan 26, 2026

By Shamsher Prakash

Equivalent spring constants for analysis of footings is a function of Young's modulus of pile material (Ep), shear modulus of soil (Gs), and geometry of the footing and/or piles. Shear modulus is strongly strain dependent in soils. Therefore, the spring constants are strain dependent, which is acceptable to the Geotechnical engineers. However, structural engineers prefer to use spring constants as a function of displacement, rather than strain. In order to develop these relationships, appropriate relationships between strain and displacement are needed. Also, modulus degradation with strain needs be built into these relationships. Description of spring constants kx , ky, and kz in x, y, and z direction and k?, k?, k?, about x, y, and z directions are relatively simple. However, description of kxø and ky?, the cross-coupling spring constants depend on 2 - components of displacement and rotation. Thus, there are 8 spring constants and likewise there are 8 damping constants. Approximate strain-displacement relationships on which displacement dependant k's and c's are based are presented with appropriate equations, and a numerical example is included illustrating k's and c's as functions of displacement.

Jan 1, 2002

By Leigh J. Wardle

SUMMARY This paper describes a numerical method for calculating the three- dimensional stresses and displacements induced by tabular excavations in a rock mass consisting of parallel layers of distinct material properties. The method is based on the superposition of numerical solutions for elementary displacement discontinuities in a parallel layered rock mass. The method can be used to analyse complicated excavation layouts such as those encountered in room-and-pillar or longwall mining. The method can automatically take into account the effect of the earth's surface. The method offers an economic and efficient solution to stress analysis problems which cannot be adequately modelled using two- dimensional methods and for which the expense of three-dimensional finite element or general boundary element analysis cannot be justified. INTRODUCTION Underground mining often takes place in tabular or lenticular orebodies. In many cases, for example room-and-pillar and longwall mining, the excavation geometry cannot be adequately modelled by two- dimensional methods of analysis. In these cases resort must be made to three-dimensional methods of analysis. Although in principle three-dimensional finite element models can be used for these geometries, cost limitations have restricted their application to a small number of cases. For example, room-and-pillar systems of regular pattern have been analysed by numerically modelling

Jan 1, 1984

By Leigh J. Wardle

This paper describes a numerical method for calculating the three¬-dimensional stresses and displacements induced by tabular excavations in a rock mass consisting of parallel layers of distinct material properties. The method is based on the superposition of numerical solutions for elementary displacement discontinuities in a parallel layered rock mass. The method can be used to analyse complicated excavation layouts such as those encountered in room-and-pillar or longwall mining. The method can automatically take into account the effect of the earth's surface. The method offers an economic and efficient solution to stress analysis problems which cannot be adequately modelled using two¬-dimensional methods and for which the expense of three-dimensional finite element or general boundary element analysis cannot be justified.

Jan 1, 1984

By André Luiz Monteiro Martins

O objetivo do projeto foi otimizar a disponibilidade e o tempo de utilização do equipamento responsável pelo refino secundário de aço líquido da CSN, o Desgaseificador a vácuo RH. Esta otimização ocorreu através da monitoração de eventos gerados por sensores instalados no equipamento para verificar quando o mesmo iniciou a operação e qual foi o tempo necessário para completar o processo. O Disponibilidade do Desgaseificador a Vácuo RH se trata de uma ferramenta gerencial que realiza o mapeamento completo da produção no Desgaseificador durante vinte e quatro horas por dia, capaz de mapear o tempo do processo com base no tempo padrão do grau de aço e tempo de parada do equipamento, apontando todos os problemas que afetam a produção.

Aug 16, 2017

By Richard W. Patton

With the advent of the Clean Air Act and the installation of flue gas desulfurization (FGD) equipment (scrubbers) on coal fired power plants, the management of solid wastes has taken on added importance. Aside from the large amounts of fly ash and bottom ash usually generated, large quantities of liquids in the form of scrubber sludge are also produced. These wastes must be disposed of within the constraints of land and water quality regulations. This paper describes the practices adopted by the electric utility industry in denting with this problem, including methods of generation and treatment, quantities and characteristics of the materials, and transportation and disposal practices. The paper also briefly describes final product characteristics and several applications for commercial utilization and land reclamation.

Jan 1, 1983

By Paul F. Ph. D. Ziemkiewicz, Courtney D. Black

According to the American Coal Ash Association, 105 million tons of coal combustion products (CCP) were produced by the power generating utilities in 1997. Of that total, 1.68 million tons were used in mining applications (ACAA, 1997). Results have ranged from the environmentally beneficial to neutral and, in some cases, detrimental. Twenty years ago coal ashes: bottom and fly ashes constituted nearly all CCPs. With the shift to new emission control technologies at power plants, however, large volumes of new products are being generated. Many do not lend themselves to traditional ash applications such as cement formulation. Many CCP disposal sites are not documented with reliable pre and post application monitoring. In this report we discuss types of CCP, their relevant characteristics and the mining environment. We have attempted to identify a range of documented applications and to draw conclusions about their environmental effects including benefits and adverse impacts.

Jan 1, 2000

By R. J. Wesely

Non-ferrous smelters traditionally have a hot gas handling system. In these systems, the dust is captured as a dry material which is often recycled to the process. Some smelters use wet gas cleaning methods with the recovery of the dust as a wet sludge. Although this sludge can be recycled to the process, in some cases it is preferable to dispose of the sludge. This paper will discuss the disposal methods available and specifically will deal with one type of sludge which has a high arsenic and high lead content. Problems with this sludge were investigated and methods were tested with the aim of stabilizing the sludge so that it passes the EPA TCLP test. Results of the laboratory tests are given.

Jan 1, 2000

By L. John Minnick

Current developments in using lime and limestone slurries to remove sulfur oxide gases from the stacks of coal- and oil-burning furnaces have established an important need for treatment systems which include adequate disposal of resulting waste materials. The paper briefly outlines the classes of scrubbers which are using lime and limestone and describes the characteristics of the by-product material being produced. Some discussion is also included relating to methods of disposal of the scrubber underflow. Since coal-burning plants also produce fly ash as a waste material, one system developed by the author's company combines this material with the sulfur oxide by-products. The mixture is processed in a manner which converts the waste products into usable materials with acceptable structural and environmental properties. Recent interest in protection of ground waters from heavy-metal leachates has made the fly ash-sulfur oxide system an acceptable means of disposal, because the conversion products have very low permeability and adequately encapsulate soluble salts within the hardened mass. Although only limited information is available on the types and chemical requirements of limestone used in these processes, a few guidelines are presented to indicate the range of materials that can be used with good results.

Jan 1, 1974