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By B Crossley

Self-cleaning fluidised bed heat exchangers have demonstrated unparalleled performance internationally for the implementation of indirect heat transfer in severely fouling fluid environments. Recent advances in equipment design have increased the scope of application to include indirect heat transfer in slurry environments, including fouling, scaling and viscous slurries. The ingenious configuration of recirculated cleaning particles through the tubes of vertical shell and tube heat exchangers provides the ability to solve heat transfer problems that arise as a consequence of tube-side fouling during indirect heat transfer to process fluids or slurries. In most cases, the cleaning particles consist of chopped metal wire, however other process-specific materials may be used.

Jan 1, 2004

By Sidney Katell

This report is the fourth in the series, Bibliography of Investment and Operating Costs for Chemical and Petroleum Plants. The initial work, Bureau of Mines In- formation Circular 7516, was published in October 1949 in conjunction with the synthetic liquid fuels program authorized by Public Law 290, 78th Congress. It included references to and abstracts of publications appearing from 1930 to September 1948 on all processes in general use in the petroleum refining and chemical industries. A supplemental bibliography, Bureau of Mines Information Circular 7705, was published in January 1955 to cover the period September 1948 through June 1952; and Supplement 2, Information Circular 7751, published in September 1956, covered the period June 1952 through June 1954. The present supplement covers the period July 1954 through December 1956.21 The information in this paper was obtained from the following sources: 1. Bureau of Mines Information Circulars. 2. Bureau of Mines Reports of Investigations. 3. Chemical Engineering. 4. Chemical Engineering Progress. 5. Chemical Engineering Costs Quarterly (Cost Engineering).

Jan 1, 1958

By M. M. Botz

There are currently more that 460 mines worldwide that utilize cyanide for gold and silver extraction. Despite this large number of cyanide-related mining operations, there have been no published accounts during the previous 25 years of the death of humans due to cyanide as a direct consequence of major mining-related environmental incidents. All published accounts of human deaths due to mining-related environmental incidents have been the result of physical inundation with tailings or waste rock materials. It appears that major mining-related environmental incidents have not been concentrated in any geographic location, are likely to occur regardless of the size of the mining company and do not occur more frequently with a specific type of mining activity. Several cyanide treatment and recovery technologies have been widely demonstrated to reliably control cyanide levels in mining solutions. With proper use of these technologies, tailings cyanide concentrations can be maintained at levels protective of wildlife while reducing the potential for adverse environmental incidents. The development of an international cyanide code of practice or management plan is recommended and should take into consideration the adoption of a weak-acid-dissociable (WAD) cyanide standard that maintains the levels entering a tailings impoundment below 50 mg/L.

Jan 1, 2001

By Tuck M. A

The increasing depth, mechanisation and distance of working areas from surface connections places an ever greater contaminant burden on ventilation airflows. Some British Coal mines are already experiencing significant problems in providing adequate climatic conditions in the working areas and have had to introduce air conditioning. Previous work has shown that in mines of low to moderate virgin strata temperature the application of controlled district recirculation could serve to improve climatic conditions at the working area.

Jan 1, 1988

By Carl Pinches

Underground or surface mining is only the first stage in the ore mining process. Once the ore is mined, it is transported to the surface for further processing. Generally, this is done to extract the particular metal or other component of the ore that has commercial value in its purified form. In its raw state, there are typically between 4 and 7 g/t (0.12 and 0.2 oz/st) of valuable material from rock mined. Once on the surface, the ore is crushed and milled in order to obtain smaller rock particles and to expose the minerals that contain the desired metal or component. Mixing the milled ore with water, a process known as ?froth flotation,? can be employed. This technique consists of a series of tanks, or ?cells? through which the process liquid flows. To obtain the maximum recovery, the milling and flotation process will often be repeated a second time. An increase between 100 and 1,000 g/t (2.9 and 29 oz/st) of rock following this stage of the process is typical. Efficient recovery is key to maintaining a profitable mining operation. The measurement and control of the froth flotation process is vital.

Jan 1, 2010

By L. Obert, D. E. Stephenson

The objectives of this investigation were to develop a laboratory procedure in which core discing could be produced under known (and variable) stress conditions, and to study the discing characteristics of several fypes of rock. Discing of rock cores refers to the formation of discs or wafers of relatively uniform thickness which fracture or rupture on surfaces approximately *Fracture is a type of failure in which there is a complete loss of cohesion and fresh surfaces are created. Rupture is a type of failure in which there Is only a partial loss of cohesion. normal to the axis to the core (see Fig. 1). Usually the surfaces of the discs are concave-convex with the concave side toward the collar of the hole. The surface of the fractured discs are like those created by a tension failure (or possibly a shear failure with virtually no normal compressive stress). This phenomenon has been observed by a number of investigators1-5 in the course of diamond drilling in underground mines, especially in areas suspected of being under high stress. The state of stress in the core required to produce discing is not exactly known. Tranter and craggs6 theoretically investigated the stress distribution in an infinite cylinder, subjected to hydrostatic pressure, minus p, from z = 0 to z = 8 and unloaded from z = 0 to z = 8, Fig. 2. The exact solution to this problem shows that a tensile stress develops in the loaded region near z = 0 with the greatest tensile stress on the axis of the cylinder. A tensile stress also developed on the surface of the cylinder at a point just outside of the loaded zone. Jaeger and Cook3 experimentally investigated the discing mechanism by biaxially loading cores in a pressure jacket sealed at the ends by O-rings. According to the Tranter and Craggs theory it would be expected that failure should occur at the pressure discontinuity at the O-rings. The experimental results showed that if the specimen was unjacketed it broke at random points within the pressurized zone and at a pressure somewhat greater than the tensile strength of the specimen, presumably due to the development of a

Jan 1, 1965

By R. G. Tarr

During an intense and accurate study of initiation systems used on an AngloGold mine, Mine A, poor drilling practices were revealed. Graphic results of all actual measurements taken are shown below. [ ] Accurate drilling of shot holes will determine whether a mining operation is payable or not and at what pay limit mining can take place. Losing 30 cm of a potential 120 cm-hole length will result in a number of consequences, i.e.: ?Higher stoping costs ?Drilling of one shot hole twice in every five shifts ?Increased explosive cost as a result ?Excess stress on hangingwall and footwall due to bad face shape ?Excessive blast damage before the area is worked out. No wonder we have such a high-risk operation. Drilling accuracy is crucial to the profitability on any mine as profits are directly related to the quality and utilization of the drilled shot holes.

Jan 1, 2000

In recent years, Computational Fluid Dynamics, CFD, has been commonly utilized in the mining industry to model the fluid flow behavior in underground mine workings. This paper uses CFD modeling to simulate the airflow behavior in underground crosscut regions, where brattice sails are used to direct the airflow into these regions. Brattice sails are cost effective ventilation control devices for temporary or permanent use in underground mining. They can be used to deflect air into the unventilated areas such as crosscut regions. Their design and installation is a fundamental issue for maintaining a sufficient supply of fresh air and achieving effective air circulation and contaminant removal. At the same time, they should have little impact on the mine ventilation system. This paper presents the results of a two-dimensional CFD model, which examines the effects of brattice length on fluid flow behavior in the crosscut regions. The results of this study will assist in understanding the ventilation air behavior and in determining the optimum size of brattice curtain (sails), which provide a highly effective contaminant removal from the unventilated mine areas. This, in turn, helps the mine ventilation designers to meet the mine safety requirements.

Jan 1, 2009

Council for 2004/2005 President F.M.G. Egerton President-elect W.H. van Niekerk Vice-presidents Senior R.P.H. Willis Junior R.G.B. Pickering Immediate Past-president T.R. Stacey Honorary Treasurer J.A. Cruise

Jan 1, 2005

By Martti Hagfors

Underwater explosions have been used as a test method for the determination of energy content of explosives for several decades. This is the only test method by which shock, gas heave and total energy values can be measured separately. The experimental data can be measured from the pressure-time curves measured by the pressure-recording unit. The shock energy is integrated from the shock peak area and the gas heave energy is calculated from the time interval between the primary shock wave front and the shock wave caused by the first bubble implosion. tb. Bubble period, tb, is the time of first bubble oscillation, the time which passes after the shock peak front to the first bubble peak. The total energy value is the sum of these two partial energies.

Jan 1, 2009

By Dave Bulled

"This paper describes the design of a molybdenite flotation circuit using FLEET technology applied to kinetics data produced from laboratory flotation testing and distributed across the blocks of a mine plan using a geostatistical approach. The geostatistics assigned the statistical error that arises from having a limited amount of sample testing data to the kinetics estimates of each block of ore in the mine plan. The final design then included a quantification of risk based on the accuracy of the block flotation kinetics and model fitting. The design made reference to the extensive technical reports describing earlier metallurgical test work including some pilot plant work over thirty years ago.The testing involved conducting MinnovEX Flotation Tests (MFT) to determine the rougher flotation kinetics at the specified reagent conditions and rougher-cleaner tests to determine the change in kinetics resulting from regrind. These flotation kinetics were used within FLEET simulations to create a full-scale flowsheet and plant design including recommended equipment sizes and the forecast of operating results. Measurement of detailed flotation kinetics for a wide range of samples allowed the effect of size of grind and efficiency of classification (i.e. width of size distribution) to be predicted for the whole ore body.INTRODUCTIONAdanac Moly Corp. proposed to develop a 20,000 ton per day mill to produce high quality molybdenite concentrate from its Ruby Creek resource in north-western British Columbia. It is a relatively clean low grade porphyry-monzonite occurrence containing minimal quantities of other sulphides such as chalcopyrite, pyrite, sphalerite and galena. Molybdenite occurs mainly as coarse flakes with lesser amounts of finer sized values. An optimum plant design was required to can achieve the predicted operating results, at a known level of risk, while treating the variability inherent in the ore body."

Jan 1, 2007

By A. Lane

The socio economic risks of mining in South Africa have been emerging for some time now, and have been brought into sharp relief by recent events in the platinum sector. The slow pace of social upliftment in the country has lead to widespread social unrest with consequent calls for different forms of resource nationalism. Fundamentally, the key stakeholders are not fully aligned, and are not engaging productively. This poses significant above-the-ground risk to mining companies. Measuring social impact, deploying inclusive solutions and engaging effectively with stakeholders are three ways in which mining companies can mitigate this risk. Keywords platinum, mining, community, socio-economic impact, stakeholders, conflict, labour unrest, social licence to operate, investment, Africa.

Mar 1, 2013

By Arild Palmström, Castro Fresno

El presente trabajo se enfoca en la información recolectada a partir de testigos de perforación diamantina, dejando de lado cualquier otra fuente de información como serían los afloramientos rocosos, laboreos subterráneos, estudios geofísicos, ensayos de laboratorio o de campo, etc. Cuando consideramos un formato de logueo geotécnico de perforaciones diamantinas, primeramente debemos evitar la utilización de formatos extremadamente grandes y complejos, no se necesita recolectar una gran cantidad de información, se necesita recolectar la información necesaria.

Sep 1, 2017

By M P. Cipold, J F. Bachmann, C C. Bachmann, J Ha

Knowledge of fuel qualities is of ultimate importance for the efficiency of chemical plants or power stations. Although most blending yards are equipped with automatic samplers and the derived samples are processed in the laboratory, the quality variation of the blended product may still be strong. This is caused by several reasons. First of all the process of sampling, crushing, dividing and analysis is time consuming. Results are available only with a delay of two to 24 hours. During this time blending is operated without knowledge of the main parameters. Conveyors with high throughput require expensive sampling systems capable of handling samples which are representative. The frequency of sampling needs also to be high in order to be representative. This results in high maintenance costs and also downtime of the sampling system.Online analysis of bulk materials has matured over time and today it can supplement but not replace laboratory analysis. As an example, J&C Bachmann has realised a coal quality monitoring system on the coal supply of a South African coal processing plant. The plant consumes ~42 Mt of coal per annum. The blending yard consists of two sets of three heaps where coal of six different mines is blended according to the factory’s requirement. From there, the blended coal is fed to the factory on two different belts.In 2010 the plant installed a TEXAS X-ray fluorescence analyser as a trial. It was tested under different conditions on several belts before the customer decided to install six TEXAS analysers on the feed belts to the stackers and two more analysers on the reclaimer belts. All analysers are installed directly on the belt and not on a substream.During the test period blending strategies were developed in close cooperation between the customer and J&C Bachmann. The use of the analysers in conjunction with the blending model has proven that the variation of the reclaimed coal quality was decreased significantly, which results in increased process performance and significant cost savings.CITATION:Bachmann, C C, Bachmann, J F, Cipold, M P and Ha, J, 2017. Online quality control of a coal blending yard, in Proceedings Eighth World Conference on Sampling and Blending , pp 125–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By K. A. Clark

SEPARATION of the oil from the bituminons sands of the Athabaska area of Alberta has been a subject of study by the Research Council of Alberta. The results of the study have been published in the Annual Reports of the Council. However, the last Annual Report in which there is mention of bituminons sand separation is that for 1934. The attention that is being directed toward the bituminons sands at the present time calls for an up-to-date summary of the work of the Research Council of Alberta on the hot-water separation process. STATEMENT OF FUNDAMENTALS OF HOT-WATER PROCESS Studies of the hot-water separation process have been largely empirical in nature. The objective sought has been a complete recovery of oil from the sand in the form of a separated oil which, itself, is free from mineral matter. Various procedures have been tried in the hope of attaining this objective and a very considerable mass of observations and background of experience have been acquired. lt is rime that a theory for hot-water separation should commence to emerge. As a start toward the formulation of such a theory, the statements which follow regarding the constitution of bituminons sand and its reactions with water and air are presented. It is not pretended that they are entirely correct, but it is believed that they lie not far from the truth. (1) Bituminons sand is an aggregate of sand, clay, oil, and water. The sand consists mainly of quartz particles of 100 ta 200 mesh size and smaller, but also of particles of other minerais including mica, rutile, ilmenite, tour-maline, zircon, spinel, garnet, pyrite, and lignite. Clay occurs interbedded with the bituminons sand, of which, also, it is a constituent. lronstone nodules of all sizes up to eight inches in diameter are likely to be present in the bituminons sand beds. The oil is viscous, naphthenic, and of a specific gravity slightly greater than that of water. The oil content ranges up to, and sometimes even exceeds, 17 per cent by weight. Rich bituminons sand from beds not invaded by water has a water content of 3 to 5 per cent by weight. The water is probably present as a film around the sand particles. The oil surrounds the moist sand grains as an envelope. (2) Water wets quartz and other siliceous minerals more readily than does mineral oil. Consequently, water tends to displace the oil film surrounding the quartz and other siliceous particles when the bituminons sand is mixed with water. Whether the oil is completely displaced depends on the properties of the water. That is to say, the materials dissolved or suspended in the water modify its wetting properties.

Jan 1, 1944

By Balu E. George, Subhadeep Banerjee, Shailesh R. Gandhi

"A three-dimensional analysis of laterally loaded helical piles installed in cohesionless soil is presented. Finite Element Analysis was conducted using commercially available Plaxis 3D AE version, assuming Mohr-Coulomb failure for soil. Pile is modelled as plate elements with a single helical blade attached to a hollow shaft. The ultimate load for various configurations is examined considering deformation criteria. The Bending Moment distribution and maximum lateral deflection are also discussed. It was observed that the ultimate lateral load carrying capacity increased by presence of helical blade and the maximum deflection also got reduced. The diameter of the helical blade was found to have significant effect on the lateral deflection, maximum bending moment and the ultimate load. However, the observations from the study suggest that the presence of helical blade seizes to produce considerable effect after a certain depth. Difference in failure pattern with regard to the distribution of soil resistance observed for different geometries considered for numerical analysis are also touched upon.INTRODUCTIONHelical piles or screw anchor piles have gained popularity due to fast installation, instant use, and other advantages over the traditional piles. They are usually used to support structures like solar panels, light houses, and other light structures which are subjected to uplift loads. However, such structures are often subjected to significant lateral loads as well. Under lateral loads, the response of helical piles can be different from that of a conventional pile due to the presence of the bearing provided by the helical blade. However, the proper design remains a concern due to lack of work carried out on the lateral capacity of helical piles.The lateral performance of helical piles is significant because they can act as efficient alternative to conventional piling systems in many applications.The lateral load capacity of screw anchor piles with different number of helices were examined by Mittal et al. (2010) by experiments in sand. They found that the lateral load capacity of piles increases with addition of helical blades. Prasad and Rao (1996) examined the lateral capacity of helical piles in clay by experiments on model piles and found that the lateral capacity of helical piles were more than that of the straight shaft piles. It was observed that the lateral capacity increase with embedment depth and shear strength of soil. Sakr (2009) studied lateral performance of two section helical piles in soft soil. The investigation by Prasad and Chari (1999) reported that the pressure distribution across the diameter is not uniform for circular piles, but it is maximum at the centre and almost zero at the two edges.Puri et al. (1984) after conducting model tests on single-helix, two-helix, and three-helix anchors installed in sand, proposed a mathematical model that was fashioned after Matlock and Reese’s elastic theory model. Elkasabgy and Naggar (2015) investigated he lateral performance of full scale large capacity helical piles in structured cohesive soils and reported the modulus of sub-grade reaction to be non linear."

Jan 1, 2017

By Kjell Karlsrud

"Abstract New semi-empirical design procedures for the determination of ultimate shaft friction and load-displacement response of axially loaded piles in clay are proposed. Hereunder also prediction of how the capacity will build up with time following the pile installation, primarily as result of reconsolidation. A main basis for developing the new procedures was detailed review and re-assessment of results from a series pile load test programs published over the past 30 years on piles well instrumented to monitor soil- and pore pressures as well as load distribution along the pile shafts. Two new alternative procedures are proposed for predicting the ultimate shaft friction; a-approach using the normalised undrained strength based on direct simple shear tests as a main correlation parameter, and ß-approach using the overconsolidation ratio, OCR. Both approaches include the effects of the plasticity index of the clay, Ip, which is shown to have an especially large impact on the correlations when Ip<25. It is recommended to use both methods in design practice, and select design values for the ultimate shaft friction that represents an average for the two methods. Pile diameter, length or stiffness, or whether the pile is open- or closed-ended seem to have little impact on the shaft friction. However, a moderate effect of pile length or flexibility on the total ultimate pile capacity comes out of the proposed t-z curves, which include some post-peak reduction. The proposed procedure for predicting the time for set-up is based on linear radial consolidation theory. The main input parameters are the insitu permeability and virgin modulus number (or virgin compression index) of the undisturbed clay. The same basic formula and correlations are applicable to both open and closed-ended or partially plugging piles.IntroductionThe design procedures presented herein are primarily based on observations and data collected in connection with “fully instrumented” pile testing programs that the author has been responsible for or has become involved with over the past 40 years, or that have been found in the literature.It was a pre-requisite for the test programs included that there were sufficient high quality soil data available to give a reliable determination of the true in-situ strength and compressibility characteristics of the clay deposits. The soil conditions range from soft NC clays with undrained shear strength down to about 15 kPa, to very stiff clays with undrained shear strength up to about 500 kPa and OCR up to 25. The plasticity index of the clays mostly lies in range 12 to 60 %."

Jan 1, 2014

By Antonio Marinucci, Robin Mao

The new Hangzhou West Railway Station, which is currently in the early stages of construction, will be located in the city of Hangzhou, China. To accomplish the ambitious goals of the project, the construction work and station building was divided into three project areas. The original design utilizes 1,580 drilled shafts with diameters of either 800 mm or 1000 mm (32 or 40 inch) to support the new Station and its various ancillary structures. The drilled shafts will be tipped into the moderately weathered argillaceous siltstone a distance between 5 and 15 m (16.5 and 49 ft), resulting in an effective pile length ranging from 35 to 43 m (115 to 141 ft), respectively. For the first phase, approximately 550 production drilled shafts will be installed. Eight (8) sacrificial drilled shafts each with a diameter of 1000 mm (40 inch) were installed to a depth ranging from 50 to 57 m (164 to 187 ft), and were tested to confirm the design parameters used for the first phase, to evaluate the contractor’s installation means-and-methods, and to provide guidance whether redesign is warranted for the subsequent two phases. Bi-directional static load testing was performed using a donut-shaped Super Cell to apply unidirectional axial loads up to 13,200 kN (2,970 kip). This paper will describe the bi-directional testing and select results obtained therefrom. The axial compressive and uplift resistances determined from the testing verified that the available axial resistance of a single drilled shaft exceeded the minimum design requirements.

By G. Hangone

Paper written on project work carried out in partial fulfilment of MSc thesis This paper investigates the effects of thiol collectors: xanthates, dithiophosphates, dithiocarbamates and mixtures of these on the froth flotation performance obtained with a bornite-rich copper sulphide ore from Okiep Copper Mine with a feed grade of 1.8%copper. Batch flotation tests were used to assess the performance in terms of mass-water recovery, sulphur grade-recovery and copper grade-recovery relationships and the Klimpel rate constant for copper recovery. The results showed that the di-ethyl-dithiocar-bamate (di C2-DTC) was the weakest collector of copper sulphide minerals. Highest copper recoveries were obtained with the di-ethyl-dithiophosphate (di C2-DTP), which were accompanied with more watery froths and lower copper grades demonstrating frothing properties in addition to collector action. Superior copper recoveries were obtained with the 90% ethyl xanthate (C2-X):10% di-ethyl-dithiophosphate (di C2-DTP) and 90% ethyl xanthate (C2-X):10%di-ethyl-dithiocarbamate (di C2-DTC) collector mixtures compared to that obtained with ethyl xanthate at an equivalent collector dosage of 0.139 mol/ton ore (a dosage equivalent to 20 g sodium ethyl xanthate per ton ore). A superior copper grade was obtained with the 90% ethyl xanthate: 10% di-ethyl-dithiocarbamate collector mixture at a dosage of 0.0695 mol/ton ore compared to that obtained with ethyl xanthate at the same equivalent dosage. Keywords: flotation, collector mixtures, copper sulphide ore

Jan 1, 2005

By A. Garassino

A pile design was performed for a thermal power station in Egypt and more than 4000 piles were to be driven. Technical economical reasons suggested the choice of driven composite LACOR piles designed for very high specific loads. Some uncertainties on the behaviour of the pile soil system suggested to perform a test on an instrumented pile. Scope of the test was to verify the possibility of developping the required bearing capacity within the range of the allowable pile settlements values and the effect of the pile joint enlargement on that portion of skin friction to be developped by the upper pile section.

Jan 1, 1991