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By D. J. Wall, T. D. Johnson, M. T. Parry, G. R. Heath

In coal-fired power stations coal is ground to a fine powder and then transported pneumatically at 25-30 m/s velocity to remote burners. Wear of the conveying pipework is a well recognised problem and traditional lining materials are Nihard and basalt. In many cases these are being replaced by alumina tiles in order to improve life and reduce the frequency of replacement. A programme of laboratory testing of candidate aluminas with AIO, contents between 85% and 99-5% has been undertaken and the results compared with field experience. This gives confidence in the erosion tests, which were designed to replicate most of the field conditions. However, it has not proved possible to draw correlations between the laboratory erosion rates and any of the materials’ bulk properties. SEM, TEM and microanalysis studies have therefore been made in order to look for microstructural aspects that could be influencing erosion rates and it has been shown that intercrystalline cohesion, the matrix phase and porosity appear to have most influence on wear performance. It is necessary to quantify these microstructural parameters if reliable erosion performance is to be obtained. This paper was read at the Institute of Ceramics Annual Convention at the University of Durham, April 1988.

Jun 12, 1905

By P. Danson, D. A. White, S. Bashir

Composite ion exchange materials made of SnO2, TiO2 and MnO2 can be used to remove radioactive contaminants from nuclear waste streams. In several cases their selectivity and capacity are enhanced by mixing hydrous silica into the matrix. MnO2-SiO2 materials are especially useful for a number of reasons, such as their selection of heavy elements over caesium. Distribution constants and determinations of exchange capacities show that in many instances the properties of the composites are better than those of the oxides alone, while the presence of a chelating agent has been found to reduce the uptake of nuclides considerably. Methods are being developed for the bulk manufacture of the materials. Further work on sorption mechanisms is required to explain anomalous results, particularly the variation in exchange capacity for different elements and the ability of the oxides to sorb colloidal material in alkaline solution.

Jan 8, 1992

By J A. Hacked

This paper explores the potential to exploit controls over the outputs of the primary blasting operation, arising from the performance consistency benefits gained in using modern bulk emulsion explosives technology. The former, allied with the latest powerful blast predictive software and measuring tools, offers the user the opportunity to apply control over both cost and performance, which has not been possible in the past.

Jan 12, 1997

By G. I. D. Roach

The leaching, with hydrochloric, sulphuric and perchloric acids, of suspensions and massive specimens of different haematite and goethite samples has been studied. Both accelerating and constant types of leaching curves have been observed. It is concluded that the grain to particle size ratio of the oxide being leached determines which type of leaching curve is obtained, particles containing a large number of individual grains producing the accelerating type of curve

Dec 1, 1971

By A. B. Holland-Batt

Deposition velocities play an important role in many fields of engineering and an impressive range of measured data has accumulated in the literature. Numerous workers have addressed the problems that are associated with the prediction of deposition velocity because of its particular relevance to the design of pipelines and pumping stations. However, despite this extensive effort, the calculation of friction heads still requires reference to experimentally based graphs to determine Durand factors and there is still scope for improvement in the prediction of the deposition velocity at different solids concentrations. Equations to characterise the relationship between the Durand factor and the volume concentrations of solids in the slurry are presented. A correlation for the prediction of the deposition velocity is also developed and tested against some of the classical experimental data. The application of predicted values of deposition velocity in assessing the potential for the sanding-up of spiral separators is then described and a case study is presented.

Jan 12, 1992

By Gibson J.

The writer hopes to prove that the economical tram is of even greater importance than, say, the economical engine, and as no difficult and involved calculations are required, and all the governing facts are simple and well known, the former is more easily attainable than the latter. In the first section of this paper the factors that determine the size and the construction of the tram are examined; whilst in the second section the road on which it runs is dealt with

Dec 1, 1916

By H. B. Bell, L. C. Smith

Measurements have been made of the activity of 'FeO' in 'Fe0'-Mn0-Ti02 melts at 1475 degrees C. The results obtained are discussed in terms of ideal mixing of titanates and in terms of a regular solution model. On the basis of the regular solution model activities of Ti02 and MnO in the Fe0-Mn0-Ti02 and Mn0-Ti02 systems have been derived. The data have been shown to be consistent with the liquidus lines in the phase systems. Examples are given of the application of the data to slag-metal equilibria, being used to derive slag-metal data between liquid iron and Fe0-Mn0-Ti02 slags

Dec 1, 1971

By T. J. White, R. A. Farnfield

Early computerised blast monitoring equipment consisted of a digital version of the existing analogue machines with, perhaps, a few enhancements. Many additional facilities have since been developed to enable the efficient collection of high quality data. These developments are examined with reference to digital sampling, triggering systems, the storage of complete recordings and signal processing. Recent advances have been made in the use of blast monitoring systems that comprise multiple blast monitoring locations with centralised control and data collection. Software has been developed to help record blast parameters and assess environmental effects. Computer databases have many advantages over their paper counterparts. Data can be easily retrieved and processed. The scaled distances used in the prediction and control of peak particle velocities can be calculated rapidly when the data are obtained directly from a database. Since the whole vibration signal can now be recorded, signal processing can be used to provide information such as signal length, dominant frequency and response spectra.

Jan 4, 1993

By T R. Marrero, J W. Wilson

This paper presents costs for a coal log pipeline that can transport coal over distances from 50 km to 1500 km. The coal log pipeline (CLP) concept is a new technology in w hich coal is compacted into water impermeable circular cylinders that can be suspended in water flowing through an underground pipe. CLP includes processes to prepare the run-of-mine coal for compaction, the injection of coal logs into a pressurised water-lilled pipeline, the conveyance of the coal through a pipe including special pumping stations, and the treatment of the coal logs and water at the pipeline outlet. An 8 inch (203 mm) pipeline can transport more than 2 Ml of coal per year. CLP components have been extensively tested in bench-scale facilities where these tests have included start up/shutdown steady state flow behaviour, end of pipeline treatment of water and coal log handling, water hammer effects, abrasion of logs and pipeline, coal log manufacture, and other engineering operations. Several sites are being considered in the United States (US) for the first commercial demonstration that will probably take place in 1998. The cost calculations are based on realistic values for all the components of a CLP. including a return on investment. For pipelines of different diameter, values for coal transportation are presented in terms of $(USVtonne as a function of distance.

Jan 10, 1996

By C G. Wall, T S. Daltaban

Three quarters of recent increases in world oil reserve estimates since 1990 have been attributed lo ‘better reservoir management' rather than to new discoveries. For the United Kingdom Continental Shelf (IJKCS), the Department of Trade and Industry (DTI) has on 2.2 bn barrels of extra oil protection through effective reservoir management of existing producing reservoirs. Past practise has been to manage petroleum exploitation on a departmental basis, with exploration assessing and ranking prospects, reservoir engineering assessing development plans and production facilities implementing plans. Any reservations necessary might involve restarting the project evaluation from scratch. Current practice is to manage an operation through asset management teams involving all disciplines. It is hoped that this approach will not only eliminate fruitless directions of effort, but the quality of work in each discipline will benefit from interaction. That is, the result of a team effort is greater than the sum of individual efforts. To date, this is most apparent with the interaction between geology, reservoir geophysics and reservoir engineering through reservoir characterization. This is the current area of greatest effort, with improved geophysical technology and computer power leading to more and more detailed and complex simulation models. The equally important interaction of reservoir engineering and production and facilities engineering applied to fields in decline has not yet achieved the prominence that it deserves. Establishing priorities in reservoir management requires the very critical evaluation of the relative value of objectives. The fact that something can be done (3-D seismic, 4-D seismic, multilateral wells, or three phase multi-layer well test analyses etc) is not a good reason for doing it. Reservoir management should he a study of value added versus cost for any activity possible or proposed. Both in the areas of reservoir data acquisition and of assessing opportunities in the period of production decline, it is likely that expert systems will need to be developed with the associated base of experience, understanding and know ledge. A n other area for the future is the elusive target of ‘enhanced ’ oil recovery, as distinct from ‘improved’ oil recovery. The most likely route forward here is the incessant scrutiny of reservoir regions and units within fields for their suitability for pilot schemes for advanced recovery techniques implemented at a favourable time. Finally, the reduction of costs, the maintenance of low. but viable rates of production and the threat of abandonment costs will increase reserves. An increase which may have appeared insignificant in the past is now more valuable.

Jan 11, 1996

By P. Rama Krishna, B. Narasimha Rao, P. Ali i Peera

Induced polarisation (IP) surveys are commonly used in uranium exploration programmes in India. The IP method is effective in detecting the disseminated metallic sulphides that are often associated with uranium minerals. However, conductive and polarisable host rock or overburden often introduces inductive or electromagnetic (EM) coupling into time domain IP measurements. This makes it difficult to distinguish between responses due to such coupling and those that might indicate economic mineralisation. Attempts must be made to remove the EM effects before the IP technique is used in drilling programmes. Transient decay curves which were recorded during field surveys at Pisnari were factorised using the Marquardt algorithm. Dispersion plots of the amplitudes and relaxation times of the composite exponential function enable a clear distinction to be made between the effects of EM coupling and those of mineralisation.

Jan 4, 1993

By R. W. Ruddle

"Besides copper, iron, silicon, and oxygen, a large number of elements may be present in copper ores, the more important of which are zinc, lead, arsenic, antimony, bismuth, selenium, tellurium, nickel, cobalt and the precious metals; impurities of less importance are calcium, magnesium, aluminium, barium, sodium, potassium, manganese, lithium, fluorine, titanium, uranium, vanadium, tin and molybdenum. All of these elements are eliminated to some degree in the subsequent roasting, smelting and converting operations.Information on the elimination of impurities during the smelting of copper is surprisingly meagre, however, rather more information is available on impurity removal during the smelting of the ore in reverberatory or blast furnaces."

Jan 1, 1953

By J. A. Franklin, E. Broch, G. Walton

To make the best use of rock core, the mechanical character of the rock should be evaluated concurrently with conventional geological observations. The advent of simple techniques, such as the point load 'nutcracker' test, makes field logging of mechanical properties competitive with sampling and testing in the laboratory

Dec 1, 1971

By G. Mellgren, O. Mellgren

The conductivity of a solution is often used industrially to control the salt concentrations of reacting systems, normally using electrodes made of glass fitted with platinised platinum electrodes. When a standard platinum conductivity electrode was used to control the acid fed to the leaching circuit for an ilmenite flotation concentrate at Titania, Norway, a deposit of calcium sulphate (containing some calcium phosphate) covered both the platinum electrode and the external glass fitting, rendering the electrode inefficient in the course of a few minutes. A new electrode consisting of a casing, two measuring tubes and an electrode stem is described and illustrated. A significant advantage of its design is that the useful range of conductivity measurement can be adjusted by adjusting the concentration of the electrolyte in the electrode. It has been in use at Titania for about four years with an electrolyte consisting of 0-1 n HCI. It is robust and demands little maintenance.

Dec 1, 1971

By C. C. Harris

The use of Alyavdin's equation Y(x,t) = 1-e(-bt) for describing the effect of grinding time on size distribution is discussed. The equation transforms into linear form by expressing it as log-log reciprocal (1 - Y) versus log t. For plotting, specially divided grids are available; Rosin-Rammler or Weibull charts may be used. The data of Herbst and Fuerstenau are especially useful for illustrating the Alyavdin-Weibull chart in two applications: (1) presenting data (which are relatively unaffected by experimental scatter) and comparing them with theoretical predictions, and (2) as a test for the zero-order kinetics production hypothesis. The chart based on the Alyavdin-Weibull equation is suggested as a useful aid in the analysis of kinetic data (/ versus f), though not as a procedure in its own right. Proposed applications are (1) displaying data with excellent clarity, since it avoids the kind of congestion inherent in some other plotting methods, and (2) as a test for assumed kinetic relationships. Sometimes, equation 1 describes the data quite closely, and in these cases the parameter values appear to be related to certain operating conditions.

Dec 1, 1971

By M. Thompson, B. Coles, M. Hale

The use in regional geochemical reconnaissance of replicate analysis of natural coatings of iron and manganese oxides on the surface of pebbles in stream sediment is described. Pebble coatings were selectively analysed for their relative contents of absorbed trace elements by ablating a small quantity of the coating with a laser beam and sweeping the aerosol obtained into an inductively coupled plasma atomic emission spectrometer. Using this procedure, a geochemical survey in northwest Wales revealed anomalous concentrations of Cu, Mo, As, Zn, Cd, Pb and Co in the pebble coatings of streams draining the mineralised Coed-y-Brenin diorite and the Dolgellau gold belt.

Jan 4, 1992

For the convenience of those who are unfamilar with thermodynamics, the following brief description and explanation is given of the thermodynamical terms and methods used in this book. It must, however, be strongly emphasized that the account given below is not an introduction to chemical thermodynamics; its sole purpose is to give the reader a rough understanding of the methods used in the earlier chapters. For further information, reference must be made to the standard textbooks on chemical thermodynamics by Glasstone.

Jan 1, 1953

By C. E. Dunn

Paper presented at the 28th International Geological Congress held in Washington DC, July 1989 (International geochemical mapping sessions). Evidence is accumulating that reconnaissance-level biogeochemical sampling can provide valuable insight into the chemistry of the substrate. Problems such as seasonal variations in plant chemistry and the lack of a universal biogeochemical sample medium may be circumvented by adopting normalising procedures. The planet can be divided into a few climatic zones, each of which is characterised by one or two common plant genera. If it can be demonstrated that the chemical differences between certain species of a single genus are small - as is suggested by studies of boreal forests - it would seem feasible to apply biogeochemistry as a low-density geochemical mapping tool. The technique could prove particularly useful for assessing the substrate chemistry of areas of dense forest, rugged terrain and difficult access by employing airborne sampling of trees from helicopters

Jul 1, 1991

By A. Hemami

In order to automate the operation of mechanical loaders it is essential to have a knowledge of the forces that act on the bucket and of the trajectory that the bucket should follow. A trajectory for the cutting edge of a bucket is derived from studies of the forces acting during the scooping phase. The proposed trajectory has a minimum energy consumption and is simple to automate. It is determined initially by setting to zero certain components of the resistive forces to the bucket motion which would otherwise result in unnecessary work and consequent energy wastage. The method for finding the appropriate trajectory is discussed on the basis of the properties of the material to be loaded and the loader size.

Jan 4, 1993

By B. H. Smith

"Most of the discoveries of nickel sulphide deposits in Western Australia have followed the search for gossans. The chances of further discoveries depend on improving our understanding of the cover of strongly leached and transported materials that obscure approximately 85% of the area of the Yilgarn Block that has nickel sulphide mineralization potential. The lateritic profiles that are observed on the Yilgarn Block today were formed over a period of more than 100 m.y. of warm and humid climates. This lateritized land surface has been preserved by induration during subsequent arid climates as well as by the structural stability of the Yilgarn Block.In geochemical surveys of lateritied terrain samples have to be taken from at least the saprolite zone usually by drilling so that confident predictions can be made of the significance of analytical data. Account must be taken of the mineralogy of samples, as well as the nature of the horizon of a laterite profile that is being sampled, owing to the concentrating effects on trace elements of Fe and Mn oxides.Multivariate techniques have been applied successfully to analytical data in gossan recognition when textural evidence is ambiguous. Pathfinder geochemistry has also been used in gossan recognition and the most significant recent advance has come from studies of platinum group metals in nickel sulphides and their dispersion during weathering."

Jan 1, 1984