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By Gene Mattila, Ron Boyd

Introduction Rock bolting is a general term that encompasses pinning, roof bolting, rib bolting, and cable bolting. Rock bolting contributes the highest nonproductive cost and is the most significant safety risk in mining today. Total installed bolt costs are now more than $20 per bolt. Rebolting or repair work doubles this. And bolting accidents account for about 30% of all fatal and nonfatal lost time accidents. It is only logical, then, for the mine operator to install the highest quality anchors possible. Every bolt on the market - tensioned, untensioned, full contact, or point anchor - has designed capabilities in axial, shear, and fluctuating ground conditions. Bolts will provide a designed support if material specifications and installation procedures fall within the manufacturer's recommendations. This also assumes that there are no unexpected geological or operational changes. Proper material specifications and installation procedures should guarantee the mine operator a quality anchor. To help assure this, the Mine Safety and Health Administration (MSHA), the US Bureau of Mines (USBM), and the AMC Manufacturers group developed stringent ASTM materials standards. These govern mechanical point anchor bolts and bolts using threaded and nonthreaded rebar. There are also minimum standards that suppliers must comply with in the manufacture of frictional bolts. However, most frictional bolt standards are based on the manufacturer's own specifications. It would be impossible to set uniform regulations on frictional bolts. Each bolt provides support in a slightly different manner and thereby requires different material needs. Quality Control In any case, material quality can generally be assured through tight order specifications and periodic quality control checks. The problem with installing quality anchors does not solely lie with the material. It includes all the events that occur from the time a bolt leaves a manufacturer to the time it is installed. The anchoring ability of any major type bolt can be affected by transportation, storage, mechanical performance of installation equipment, installation demands of the operator, proper drilling accessories, and local geology. Table 1 and Fig. 1 document the negative events that can affect each bolt and the degree to which it can be affected. Drilling a hole of oversized diameter, for example, is an operator controlled factor. It will adversely affect most bolts. An over-sized diameter reduces, or even eliminates, the anchorage capability of a mechanical shell. It will reduce the support capacity of a split set to nearly nothing. And it will cause a partial or incomplete grouting around the resin bolt. Frequently, due to bit wear, holes are drilled undersized in diameter and may not be properly cleaned out. In this case, it will be difficult for the operator to push the mechanical shell into the hole, thereby causing him to drill another hole. In cases where the bolt is obviously not providing anchorage, operators will probably drill another hole and place another bolt. Rock Bolt Regulations It is the situations where a bolt is improperly installed in the hole, but gives the appearance of a good bolt, that are frightening. In fact, some safety officials and engineers believe that only 50% to 60% of installed bolts are working. These bolts cause irregular ground load transfers in other bolts and overload them. This causes hazardous situations and overstressing. It is these bolts that fail prematurely 200 to 255 mm (8 to 10 in.) behind the face and possibly contribute to the high accident rate. The government and several manufacturers recognized the need to check the integrity of rock bolts. These programs are in different stages today. Tight torque regulations have been established for mechanical

Jan 4, 1985

By Jianjun Tang, Wenjuan Bai

This paper presents a new method of formulation design for multi-component composite explosives. Based on the thermochemistry of the detonation process, the mathematic model of formulation design is established by optimization mathematics. Using the heat of detonation as target functions and taking the constraint conditions such as oxygen balance and costs etc into consideration, this model can provide an optimal solution quickly by means of personal computer. Using this method, the calculation and the simulation tests for a series of constituent sets and various constraint conditions can be conducted easily. In this way, the optimal formulation for the explosive can be determined, on the basis of the maximum heat of detonation and the lower cost.

Jan 1, 1997

By J. Miettunen

"The lining of a grinding mill has an important role in creating the conditions for the grinding process. The main purpose of the lining is to transfer the energy taken by the mill motor to the contents of a mill. The power draw curve of the mill, if measured with sufficiently short intervals, describes how well the lining works in lifting and mixing the material to be ground.The power draw curve can also be used for determining the volumetric filling of a mill. This new measuring technique was developed at the Pyhasalmi concentrator in 1989-90. The measuring device with its PC-connections offers an excellent tool for controlling volumetric mill filling, for maximizing throughput and for research purpose (e.g. process studies, mill linings design).The paper describes the new method and the results achieved at Outokumpu's concentrators.INTRODUCTIONVarious methods have been developed for measuring mill load; weighing, noise, etc. Weighing is one of the most reliable methods but installing the sensor to existing mills is often difficult. Besides the load measurement does not indicate the volumetric filling if the specific gravity of the mill feed fluctuates. Noise measurement has often failed with its sensitivity to various disturbance sources.As known, the power draw measurement is one of the most accurate measurements in grinding circuits and therefore it has been utilized in sophisticated control, e.g. in power peak seeking algorithms for maintaining maximum grinding efficiency.About 10 years ago power oscillation measurement was developed at Pyhasalmi concentrator. In this method the amplitude of the oscillation caused by the lifters was measured. The oscillation amplitude and the mill filling has quite a good correlation and together with the power draw measurement it could be used for maximizing mill throughput (Koivistoinen and Miettunen, 1989). The main difficulties in this method were that the dependence between mill filling and the amplitude is unlinear and that the dependence also is individual for each mill.The method developed during 1989-90 is also based on the power oscillation but on its phase shift. In principle level of the material in a mill is measured. The method has been successfully used for maximizing throughput at Pyhasalmi and Enonkoski concentrators and at Harjavalta slag concentrator."

Jan 1, 1991

By G. J. Borbely, E. A. Devuyst, V. A. Ettel

"A new method for oxidative destruction of cyanide in industrial waste waters and slurries, such as gold mill barren liquors, tailing slurries and flotation tailings has been developed at the Inca research laboratories. Rapid decomposition of cyanide and related species is attained by treating the waste waters with a mixture of S02 and air at controlled pH and in the presence of a small amount of copper which acts as a catalyst. The approach selectively oxidizes cyanide and metal cyanide complexes, and also removes iron cyano complexes which are not removed by alkaline chlorination.The new method is shown to be less reagent intensive and therefore more economical than alkaline chlorination for treating gold mill and flotation waste waters. INTRODUCTIONOver 90% of the gold mined in Canada is extracted from the ore by ""cyanidation"". Wastes from the process consist of tailings which contain free cyanide, cyanide combined with heavy metals, thiosalts and thiocyanates. Because of the concern over the effect of toxic cyanides on the environment, all cyanide containing effluents will have to be treated in the future to meet certain government set concentration limits."

Jan 1, 1982

By David A. Lee

It was estimated in Chemical Week1 that the uranium fuel requirements for the U.S. Electric Utility Industry by the mid 1980's would be about four times that-of what it is today. This corresponds to approximately 45,000 tons per year of 'yellow cake' - of which a good portion is represented by ammonium diuranate - vs. the 11,700 ton total estimated for 1975. Perhaps just as significant is the 40-fold increase in thirty years projected for the entire world since 1970. Thus by the year 2000. 'yellow cake' production could be in the order of [3]50.000 short tons annually.2 'Yellow cake', so named because of its inherently bright yellow color, is a finely divided precipitate that can be formed after the leaching step when refining uranium ores. Feed solids enhancement then occurs to at least 50% by weight using filters or centrifuges This is followed normally by drying and then calcining with the conversion of ammonium diuranate to triuranium octoxide represented by the following equation: [9 (NH4)2 U2 07 heat 14 NH3 7 + 15 H2O7 + 2N2/ + 6 U308 4] Theoretically, assuming 100% conversion every 100 kgs. or 100 lbs. of ammonium diuranate will result in 90 kgs. or 90 lbs. of triuranium octoxide.

Jan 1, 1976

By Larsson Lars-Erik, Rani Isa, Martin Jönsson, Håkan Bredenberg, Mats Larsson

"IntroductionSteel Core Piles are used extensively in Scandinavian countries, where hard rock is found within reasonable depths. A steel core is cast into a drilled steel tube casing and a rock hole is extended below the casing. This pile type is considered a very reliable type of pile, and for urban environment it has several advantages compared to other types of piles. One critical phase of the installation is the drilling of the casing. Usually a DTH (Down The Hole) hammer is used. Drilling in fine grained soils, e g silt, below the ground water level, may give rise to an excessive volume of soil material flushed up from the point of the casing, resulting in unacceptable settlements around the pile installation area.Using a new method for drilling of the casings, the ELEMEX-method has proven to significantly reduce the risk for such problems. In the paper a case record from a ground improvement project in central Stockholm is described. Ground settlements around the drilling area were carefully monitored over a longer period. Both the new drilling method and the conventional DTH casing drilling method where used, so that the corresponding ground settlements could be compared. Settlement records and comments are included in the paper.The paper also gives a description of the project. The installation of new piles and foundation constructions cover a whole city block in Stockholm downtown. The reason for the replacement of the old, damaged wooden piles were due to their destruction caused by a long time lowering of the ground water table. The paper gives a description of the new drilling method as well as an overview of usual urban foundation issues and their solution in Sweden, Finland and Norway.Drilled Foundation MethodDrilled Foundation, using drilling methods originally developed for drilling of large diameter rock holes, is today a standard method for the installation of piles, tiebacks, drilled pile walls and other foundation components, especially in urban built up areas where other techniques as drop hammers, augers, vibratory hammers and other equipment fail to meet the requirement, se ref(1). Drilled foundation is for example used for"

Jan 1, 2014

By Catalin Florin Petre, Elahe Ghasemian Langeroudi, Abdelaaziz Azizi, Éric Proulx, Caroline Olsen, Paul Blatter, Faïçal Larachi, Claude Gagnon

"The recovery of gold from ores is often accompanied by the release of other species in the leach solution. This state of affairs leads to depleted free cyanide levels in the slurry. Therefore, separation and quantification of these cyanicides and free cyanide at different stages of the cyanidation process as well as in waste solutions is crucial to provide mitigation tools by preventing leaching of deleterious metals for environmental considerations.COREM and the research group of Prof. Larachi have been working together on the control of gold passivation and cyanicides during cyanidation for several years. Previously, a first capillary electrophoresis (CE) protocol for the speciation of sulfur and cyanicides (SCN-, Cu, Fe) during cyanidation of gold complex sulfide ores was developed and validated for assessing industrial process water.The separation of zinc cyanide complexes used to be confronted with a number of difficulties due to the weak and/or undetectable cyanocomplexes in formally available CE protocols. Moreover, according to our knowledge, no direct CE protocol exists to separate free cyanide. Therefore, a new study aimed at developing a second CE protocol for the detection and quantification of cyanide complexes of zinc and nickel as well as of free cyanide in the cyanidation process water.To achieve this goal, six common carrier electrolytes such as pyridine, trimellitic acid, 4-methylbenzylamine, sodium chromate, phthalic acid and tris base were studied, using an indirect UV detection method. The best results were obtained using sodium chromate for which all ions were successfully separated and quantified. In addition, the effect of electric field strength, injection volume, electro-osmotic flow (EOF) modifier and background electrolyte (BGE) concentration were examined, while peak height, peak area and noise were considered for optimization.As a result, the new protocol is expected to complete the initial CE protocol by detecting cyanide complexes of zinc and nickel as well as free cyanide. Moreover, analytical determination of free cyanide in the presence of weak cyanide complexes achieved by the new protocol was also compared to conventional titration using silver nitrate solution. This new CE protocol will contribute to applied research and help plants to better understand and eventually control the behaviour of cyanidation circuits."

Jan 1, 2011

By P. James

"INTRODUCTION High sulfate (SO4-2) levels often occur in MIW (mining influenced water) either as the result of oxidation of sulfide minerals exposed by mining activity or by deliberate addition – commonly by sulfuric acid (H2SO4) use in hydrometallurgical leaching activities. Increasing regulation of sulfate discharge is creating new pressure to treat or mitigate sulfate release to prevent its entry into the environment. Current treatments include precipitating as gypsum during lime treatment, filtration separation using membranes such as reverse osmosis and nanofiltration technology, and biological elimination via methods like constructed bioreactors. Blue Planet Strategies (BPS) focuses on improved resource utilization targeting electrolytic treatment and waste conversion into resources and has now demonstrated that its proprietary DEMET™ (Dynamic Electrolytic Metal Effluent Treatment) platform can also remove sulfate from target streams as a byproduct of its usual primary treatment focus points of metal species elimination and/or pH adjustment.[1-6] This powerful new capability can mitigate sulfate contamination and recover the sulfate in a useful and potentially saleable form as a byproduct of improved primary treatments focused on enhancing production or treating waste. This provides a new treatment opportunity and value proposition for lowering overall sulfate consumption/addition or creating new revenue to defray conventional treatment costs. The DEMET Alternative DEMET utilizes a patented electrolytic technology platform employing proprietary dynamic high surface area electrodes in innovative configurations to achieve a variety of novel selective chemistries. DEMET‘s unique elements can yield higher processing rates at practical efficiencies, lower energy consumption, plus improved processing stability and lower maintenance requirements due to enhanced resistance to cell fouling and shorting; while also thwarting cross stream (catholyte vs. anolyte) contamination. Consequently, DEMET can provide a superior, extremely versatile, and cost-effective electrolytic treatment option where a multitude of FEED and PRODUCT stream combinations might be employed in comparison to traditional tankhouse electrolytic cells. Secondary reactions (Figure 1A) which could also occur at the cathode (plating/electrowinning, precipitation/scale formation, etc.) are controlled through process tailoring and operation parameter selection. Additionally, DEMET‘s innovative dynamic system mitigates potential fouling and electrode occlusion or shorting challenges which could occur when process particulars demand some of these secondary side reactions occur."

Jan 1, 2015

By Leonard Grimshaw

THE idea of bonding two dissimilar ferrous metals, and making use of both, is an old one. Tips have been brazed onto tool shanks for many years. The bonding of larger pieces to form whole bars and sheets has also been accomplished, but has received little attention in the technical literature, although a number of patents have been issued covering various methods for its accomplishment. There are three main motives behind the manufacture of composite steels. One is that the physical properties of one steel may supplement those of another; a useful, but at the same time, hard, brittle steel may be backed by a soft ductile one, or a stainless steel may be backed by a steel possessing greater strength. Another motive is direct lowering of cost; an expensive steel may be backed by a less expensive one, bringing down the cost of the piece as a whole. The third motive is an indirect lowering of cost, as when a useful steel is backed by a steel that is easier to machine, so that machining cost on a finished product is lowered considerably. Often more than one of these motives lead to a decision to use a com-posite steel.

Jan 1, 1936

By Tracy L. Atherton

THE mapping of slant-hole oil fields is complicated by the fact that relationships between wells are subject to variations in three dimensions and are not readily adaptable to representation on a plane surface. Formalized perspectives usually expand into an undecipherable maze of lines and peg models with the necessary supporting dividers serve only to awe the beholder with their perplexity. The usual compromise arrived at is a plotting of the projection of the courses of all of the wells in the field onto a horizontal plane (Fig. I). These complicated plots, when used in conjunction with the individual vertical projections of the wells, heretofore have been the most practical foundation for the study of general field problems. This method has many shortcomings, however, which are not found in the recently developed straight-hole equivalent projection method. The new method supplies a series of maps similar to the type now in common use in straight-hole fields. It is remarkably simple to use and supplies a ready check on clearances between wells. Perhaps the method can best be understood if the steps that led to its development are described. Common practice of oil-well surveyors is to supply the owner with a tabling of the survey and a plan view plotted against the true meridian. If a vertical projection is plotted, it is usually plotted separately and shows vertical depths against the projection of the stations along a section line joining the top and bottom of the hole on the plan view. A more practical method would be to plot the section line of the plan parallel to the abscissa of the vertical projection (Fig. 2). If this is done, any line parallel to the "base line" will pass through the points on each projection that represent a single point in the hole. Another very useful graph, which the well surveyor could provide, would be plotting of vertical depths against measured depths. Fig. 3 illustrates the next step facilitated by this form of plotting. The lines designated "well A" represent the proposed course of a hole to be drilled. Superimposed on the drawing, in its proper relative position, is the plan view and a portion of the vertical projection of a present producer, "well B." From an inspection of the plan view we arrive at the correct conclusion that the only indicated possibility of collision is at the point of crossing of the wells on the plan view. Referring to the vertical projection, note that the vertical depths of stations on B, in the vicinity of the crossing, are plotted on the same plane of projection as A. The clearance is the indicated distance between the two vertical sections measured along the parallel to the "base line," which passes through the point of intersection of the plan view. Repeat this process for the other wells crossing the proposed course of A on the plan view and you have a preliminary check of clearance for the proposed course. A similar comparison of crossings on the vertical projections of all

Jan 1, 1941

By B. Cousins

Flotation reagents are critical to the optimum performance of flotation circuits. How a flotation reagent performs within the first few cells of a flotation train is a key indicator of how well it will perform throughout the entire circuit. A method to compare reagent performance was recently developed by Ashland Water Technologies. The procedure involves collecting a timed sample of concentrate from each cell and then measuring the volume of the settled solids. An estimate of the percentage of concentrate collected from each cell can then be mathematically determined, providing an understanding of the recovery changes in each cell. Data from trials at a coal flotation circuit are used to demonstrate the method's validity.

Feb 27, 2013

By Jorge Cárdenas, José Luis Hurtado

The critical distance determination test through direct recording for the mine in Phase 03 was carried out in January 2024, and in it the vibration and pressure models were obtained for the Sedimentary breccia unit. The method of obtaining the records is based on the capture of individual pressure waves generated by distant loads, sequenced in periods of 600 ms for easy identification. The test set up corresponds to a variation of that used to obtain the vibration model, and uses 08 wells for loads and 04 for instrumentation. The results apply a safety factor of 1.2 and 1.5, being 16,000 PSI and 13,250 PSI respectively. The values are valid for any distance greater than 5.5 m, this being the minimum established between wells for loads according to the configuration defined in the field, also considering that in 5.0 m of instrumentation the section of the drill hole with the sensor called S1 collapsed. The results of the analysis of the test, generated with Heavy Anfo 82 explosive, with a final density of 1.15 g/cc, are presented. The results of the modeling and generation of the graphs and tables presented show behavior in line with the concept of scaled distance. It is important to consider that in water conditions there is a high impact by the condition, which causes the records to be higher than those expected in dry conditions and present less variability. It is for the above reason that the row corresponding to distance with safety factor 1.5 is declared valid. The results are only valid for the rock analyzed, whose medium is homogeneous and constant in terms of lithological composition and that present similar resistance characteristics, fracture frequency and water table levels. As future steps, the objective is to quantify the increase in pressure generated between wells by analyzing time and sequence factors. This analysis aims to explain the occurrence of dynamic pressure events in areas where critical safety distances are observed.

Jan 21, 2025

By Guillermo Lazcano Ríos, Jorge Parvez Aguirre, Alejandro G. Díaz Berríos, Felipe Rodriguez Alveal

Codelco's Chuquicamata Underground Division (DCHS) faces issues due to collapses in its subsidence streets, which hinders the advancement of the subsidence front and leads to the loss of areas and reserves. To address these issues, DCHS and Orica have developed a new excavation methodology based on pre-loading explosives in high drawbell. This methodology involves creating a high drawbell extending from the floor of the production level to the ceiling of the subsidence level, divided into two phases: upper and lower. A resin stemming is used to separate these phases. The excavation strategy adjusts to variables such as reception volume, fluffing, and excavation geometry, involving vertical pre-loading of the explosive and the use of a separating element between the phases. The test aims to validate the new excavation methodology and the retaining element in the rock mass, evaluating aspects such as drawbell geometry, impact on the rock mass, damage to the retaining element, and fragmentation. Wireless electronic detonators are used in the upper phase to improve safety by eliminating the need for physical connections, while traditional electronic detonators are employed in the lower phase. Low-density bulk emulsion is applied to minimize the impact on the Crown pillar and extraction point, and higher-density explosives are used above the subsidence level to ensure good caving. Results showed that the blast achieved 86% conformity with the theoretical design. Resin stemming allowed for 100% effective detonation in the upper columns, and the fragmentation obtained was 5.44 inches, which was less than expected. No damage to the Crown pillar was observed, and the explosive quality met standards. This technique has proven to be effective and viable, suggesting the possibility of eliminating the subsidence level in future levels, resulting in savings, and providing greater stability to the rock mass.

Jan 21, 2025

By José Aparecido Pereira

The innovative methodology developed by the author allows the elaboration of an Angle Roll Pass Design based on the practical observations of the rolling process and applies mathematical criteria, using the Ekelund´s formula supported by Advanced Excel tools (Reach Goal, PROCV-PROCH, Macros) and AutoCad. The first step is the definition of the number of stands, roll dimensions, gear boxes reduction, initial stock, average reductions, spread factors, finishing speed and type of grooves. For each pass are calculated: bite angle, spread, section reduction, lost and gain of temperature, separating force, speed, torque and motor power. After these calculations and checking of the parameters, the program calculates the dimensions of the passes transforming the flat passes into shaped ones. With these dimensions it is possible to draw the grooves using AutoCad and check section reductions. This methodology was already used for the development of a new project and also to check the parameters of existing ones, with comparison of the results and has shown to be reliable in real and tested projects. It is an innovative process that is not available in known literature.

Oct 1, 2019

By Mats Keisu, Bengt Niklasson

The Sofia project has increased the level of knowledge and technique within tunnelling, drifting and contour blasting.

Jan 1, 1992

By H Han, W Wang, E Zhou, D Duan

"In this study, physical, chemical and microscopic characteristics of high phosphorus oolitic hematite were studied firstly. Based on which, the new methods of high phosphorus hematite used in the æsolid state reduction by rotary hearth furnace - magnetic separationÆ and iron nugget by rotary hearth furnace direct reduction processes were discussed. The results showed that high temperature, low basicity and high carbon content is conducive for the apatite in iron ore to reduce into molten iron, but not conducive to the removal of phosphorus. Through optimisation of process parameters, dephosphorisation rate of high phosphorus hematite is more than 60 per cent by æsolid state reduction roasting-magnetic separationÆ process while that is up to 80 per cent by iron nugget process. This study can provide theoretical and technical basis on economical and rational use of high phosphorus oolitic hematite.CITATION:Han, H, Duan, D, Zhou, E and Wang, W, 2013. New methods for high phosphorus oolitic hematite dephosphorisation by direct reduction process, in Proceedings Iron Ore 2013, pp 391-396 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 12, 2013

By H. Kempton

New methods for remediating metals-contaminated groundwater include in-situ emplacement of highly adsorptive substrates to permanently retard solutes. Substrates are introduced by sequential injection of soluble components that precipitate in the aquifer, forming a permanent high-retardation zone. This method overcomes the factors that limit pump-and-treat remediation; i.e, long-term source loading and slow desorption. Column tests demonstrated efficient substrate emplacement, increasing retardation coefficients of Cr(VI) by 20 and As(V) by 40. Similar effectiveness is expected for other heavy metals. Simulations using a coupled advective-geochemical model accurately matched substrate emplacement and arsenic attenuation, allowing extrapolation to other constituents and larger-scale applications.

Jan 1, 1999

Remote sensing techniques can be used to map joint sets in a rock mass for the estimation of in situ block size distribution and improved optimisation of blasting. This paper reviews remote sensing using photogrammetry and laser mapping for mapping rock masses and presents elements of the analyses applied to data acquired with these mapping technologies. These techniques enable a user to map areas of hundreds of square metres rapidly with high precision. Using this data computer programs such as Sirojoint can provide estimates of joint position and orientation with orientation measurement accuracies better than one degree. The paper describes the use of remote mapping and provides potential users with a description of some of the advantages and limitations of the mapping techniques and the data they produce. Mapping of lithology and structure of rock masses is an important task required in many areas of mining and construction. It is a complex task routinely performed using established techniques developed to provide consistent results under a wide range of conditions. The techniques for data acquisition and analysis described in this paper enable more accurate mapping to be performed rapidly and enable mapping of inaccessible sections of a rock mass. These techniques will provide geologists and geotechnical engineers with more detailed, accurate data than previously available.

Jan 1, 2001

By D FitzGerald

A critical component of any new tunnel design in a complex geological setting is the development of an integrated three-dimensional (3D) geology model with a full set of geotechnical properties of the rocks present. A novel means of predicting the geology based upon sparse observations of structural geology at the surface and from drill holes has been developed and used in several major tunnel studies in Europe.An example of this is the Lyons-Turin twin rail tunnel which is still in a development phase. This tunnel has been in planning and development for over 15 years already. An important aspect of this work is to characterise geological uncertainty along various possible tunnel paths as an input into early design optimisations for time, cost and risk avoidance strategies. Once the tunnel works commence and more detailed geological data is collected by daily mapping, progressive refi nement of the geological model is desirable; geological conditions still to be encountered can be more accurately predicted. Faults and their offsets, dykes, geological unconformities, folding, as well as standard sedimentary processes are all correctly modelled in the software. It is important to allow for seamless interchange of geological models at various scales with CAD workflows so that sufficient detail can be readily accessed at the required scale. Also, the proposed tunnel in its correct geometry can become a ‘section’ in its own right. Progressive detailed local geology models in the vicinity of the advancing head are created from the regional scale work by cutting and pasting a starting model, then adding all the extra detail for the required engineering geology work.For all rocks, most standard geotechnical quantities such as sonic velocities, Young’s modulus and Poisson’s ratio are handled. These and any other phenomena from borehole observations can have variograms calculated and stratigraphically constrained estimations made in a least biased geostatistical manner, in advance of the tunnel. RQD, or a prediction of rock fractures, is handled by the faulting and folding modelling facilities. This is probably the more interesting issue to pursue, as the fractal nature from small scale fractures and joints, to large-scale faults, can now be characterised more convincingly.

Mar 8, 2011

By Jamsa-Jouneia SL, Lahteenmaki S

Sophisticated control systems require sufficient and reliable information from the process to be controlled. At the Pyhasalmi concentrator two novel measurements, a particle size indicator (PSI) and a mill level monitor (MLM), have led to significant progress in the control of the grinding circuit. The PSI and the MLM measurements have brought additional information from the process. The PSI has been an absolute prerequisite for determining the overall grinding circuit efficiency and the design of the integrated grinding and flotation control system. The MLM measurement has enabled studies on the volumetric filling of a mill to be utilised for maximising the mill throughput. The paper describes the operation principles of the PSI and MLM devices and the additional process information received. The results of a metallurgical pre-control audit are discussed and finally the design of the integrated control system is outlined.

Jan 1, 1993