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By The Mill Staff

"IntroductionCOMMENCEMENT of operations at the new No. 7 shaft and 10,000-ton mill at Creighton mine was a major step in the programme of conversion to all-underground mining by the International Nickel Company of Canada, Limited. Planned ten years ago, the orderly transition has been greatly speeded-up to offset the heavy drain on production imposed by World War II and also to meet the increased demand for nickel caused by the current international situation. Development of new mining methods, and process changes in the reduction plants, have made possible the economic recovery and utilization of ore of lower grade than formerly used and of varying metallurgical characteristics. By 1953, when the Company's open-pit mining operations are scheduled for completion, the hoisting capacity of its five underground mines in the Sudbury district will have been increased to 13,000,000 tons per year, compared with 5,700,000 tons of underground ore hoisted in 1950.Two types of ore occur at Creighton. One is a breccia and stringer type that contains a high percent-age of massive sulphides and is located in sheets along shears and in large and small pockets on the underside of the main norite mass; the other type, forming the main part of the ore zone, is mineralized norite that occurs as a •sheet up to 400 feet thick overlying tl1e breccia ore. In both types of ore the minerals of economic interest are pentlandite, which is intimately associated with pyrrhotite, and chalcopyrite. Early mining was confined to the breccia ore; this ore was mined by open stoping methods. The hanging-wall was later allowed to cave, with the result that the old stopes are now filled with caved low-grade ore."

Jan 1, 1952

By Julian Boldy

"A review of lI5 significant volcanogenic massive sulphide discoveries in the Canadian Precambrian during the past 65 years reveals that only 7% resulted from surface exploration methods aimed at depths below the effective reach of current geotechnical systems. This has been due to the relative ease of shallow discovery, resulting in the harvesting of ore deposits within 100 m of surface. This surficial layer has been more or less effectively supersaturated by routine exploration. In view of the fact that a mining district's metal content is not likely to be confined to a surficial layer, the time has come to explore the vertical dimension, prospecting for ore at depths in excess of 150 m in productive districts.Essential to this task is an understanding of the Precambrian volcanogenic ore deposit model. The deposits generally have .a tendency to be associated with the terminal phases of felsic volcanism, and to be located along certain time-stratigraphic horizons, marked by the products of volcanic exhalation. The significant massive sulphide deposits are discrete entities, ranging from the top 5% of deposits greater than 45 million tonnes in size, with a surface area of 0.30 km2, to median-sized deposits greater than 1.2 million tonnes in size with a surface area of 0.02 km2. These significant economic ore deposits range in value from $5.5 billion for the top 5% of deposits to $125 million for median-sized deposits. In terms of their frequency of occurrence, the former group has a 4% distribution and the median-sized deposits have a 15% distribution.An historical review of many of the principal Precambrian mining districts, such as Noranda and Flin Flon, shows that major tonnages are usually discovered during the initial phase of application of each new geotechnical search system, until carried to its ultimate limit of effective depth penetration. With the exception of the Noranda district, the mean depth of ore discovery in the other districts is still generally confined to within 50 m of surface.Targeting deep ore is difficult. One effective prospecting method is the detection of fracture-controlled mercury leakage haloes in outcrop (or core) above and peripheral to blind deposits. This technique has proved to be a useful pathfinder, and focuses attention on deposits buried at depths in excess of 700 m in some instances. Down-hole EM systems also promise to be effective in locating deposits previously bypassed by drilling. In addition, trend surface analysis programs of trace element geochemistry should be used as an aid to targeting ore by directing exploratory drilling along the plane of ore-hosting stratigraphy.By definition, mining districts have a proven ""favourability"" for the occurrence of ore. Discovery probabilities in these districts will be considerably enhanced if future search efforts are concentrated below a depth of 150 m, and more use is made of ""deep"" ore search systems coupled with sound geological reasoning. Deep drilling programs to a depth of800 m should initially be designed to search for the top 25% of deposits greater than 3.3 million tonnes in size, with a surface area of0.05 kmt. :a value of$310 million and a 12% frequency of occurrence; This can be accomplished for an over-all cost approximating $40,000 per drill hole. If the search depth is limited to 400 m, the over-all cost of each drill hole is $20,000, equivalent to expenditures routinely allocated to grassroots exploration drilling in the remote greenstone belts of the Precambrian. Depending on a company's objective, prospecting for deep ore offers a stimulating challange - though risky, it has its rewards."

Jan 1, 1981

By J. Guha, R. Kanwar, G. Archambault, A. Tremblay

The Copper Rand Cu-Au deposit lies within a shear zone which strikes N50-60W and dips steeply southward (50°-55°) and extends over 1. 5 km with a thickness which varies form 350 to 425 metres. Mineralization, inside the shear zone, is structurally controlled by a dilation mechanism which can be explained by a fracture dilatancy model. The principle of this model involves the mechanics of overriding of irregular planes and surfaces of faults and schistosities, These structures are characteristic features of the Copper Rand shear zone. A structural analysis of the shear zone has been carried out to establish relations between the different structures within the shear zone and their evolution with the development of the shear zone. A geomechanical interpretation of the Copper Rand shear zone explains the formation of internal structures such as faults, schistosities and microstructure during the shearing. This interpretation confirms Ramsay's theoretical model on the geomechanical evolutuion of shear zone development, and the experimental work of Morgenstern-Tchalenko on the simulation of shear zones in clay models. The geomechanical interpretation of the shear zone demonstrates that at the onset, subsidiary fracture patterns are developed in second order faults in the following sequence. At peak strength Riedel shears ( R and R') are formed which propagate outside the strength, restraint (P) shears are developed in the thrust attitude within the shear zones. Principal displacement shears (D) develop toward residual strength in the direction of movement. Shear lenses are formed by the interaction of these shear discontinuities and these facilitate the formation of schis tosi ties with the continuation of the shear displacement within the main shear zone. While the main shear zone and the P and D shears within the main shear zone were in continual movement, the Rand R' structures, once formed, retained a simple fracture pattern and moved little outside the shear limits in comparison to the main shear zone. Parts of these structures inside the shear zone were reactivated by subsequent movements and deformed into folds to account for the present attitudes of the HW-1 and HW-2 and HW-3 structures. This geomechanical model for the shear zone with its subsidiary structures (R, R', P and D shears) is also applied on a larger scale to the Dore Lake shear belt and explains the different structures accompanying it. The initial development of the WNW shears (most are ore deposits) was followed by the subsidiary structures of the Dore Lake shear in a north-south stress field and is well defined by the movements characteristic of the different structures. It is concluded that the Dore Lake shear cannot be the prolongation of the McKenzie Narrows shear but it seems that this prolongation relates to the Henderson-Portage shear zone.

Jan 1, 1984

By L. T. Pasiechnyk

After a brief review of the various hydrocarbon storage methods currently being utilized and statistics on underground hydrocarbon storage, this paper will briefly describe the technology involved in solution mining salt to create caverns of engineered shape and size and briefly discuss the economical and environmental advantages of hydrocarbon storage in solution-mined salt caverns. Other possible uses of salt caverns will be mentioned.

Jan 1, 1978

By H. M. Woodrooffe

This paper deals with the laboratory facilities at the Mines Branch for carrying out research in the industrial minerals field, and also reviews current programs in ceramics and construction materials, in non-metallic minerals and in the milling of industrial minerals. It then discusses the application of these pro-grams to industrial problems.

Jan 1, 1967

By J. A. MacLellan

"CONSTRUCI'ION OF SHERRITT'S CONCENTRATORSSherritt Gordon is operating two mills north of the 56th parallel, and is presently engaged in building a third. The author was closely involved in the design and construction of all three of these concentrators.The Lynn mill is the oldest of these three concentrators-it is a 4,000 ton per day nickel-copper plant built in 1953. The Fox mill is a 3,000 ton per day copper-zinc concentrator built in 1970. The Ruttan mill will be a 10,000 ton per day copper-zinc plant scheduled to go on line in July 1973.LYNN MILL The Lynn mill including the crushing, concentrating, drying and load out plant is about 69,700 square feet or 17.4 square feet per ton per day. '!his plant was originally built in 1927 at Sherridon, 150 miles south of Lynn Lake, as a 2,000 ton per day copper-zinc plant. In 1952 the plant was moved by tractor train to Lynn Lake. The whole plant was re-oriented within the original perimeter walls as a 2,000 ton per day nickel-copper plant. This plant was expanded to 4,000 tons per day by the addition of t1-Jo rod mills and a 5-1/2 short head crusher in 1959.The Sherridon mill processed its last ore in Sherridon in September 1951 and the first load of nickel concentrate was loaded at Lynn Lake on November 9, 1953 when the railroad arrived at Lynn Lake.The site for the Lynn Lake mill was cleared of overburden in the summer of 1952 and foundations for structural steel and SO!l8 equipment foundations were poured the late summer and fall of 1952 • Steel was erected from January to June 1953. Most of the equipment came in from January to March of 1953 by tractor sleighs. Sane sleighs upset but no equipment was lest through the ice."

Jan 1, 1972

By The Staff

"THE Wabana iron ore mines, owned and operated by the Dominion Steel and Coal Corporation, Limited, .are on Bell Island in Conception bay, on the east coast of Newfoundland. Mining began on surface in 1895 and, although open-pit work is still done on a small scale, the entire output may be considered to•be derived from extensive submarine workings. In 1958 the average daily production of hematite ore was close to 12,000 tons, almost all of which was concentrated in a heavy-media plant. SUMMARYThe character, occurrence, and extent of the submarine bedded deposits enabled early operators to meet prevailing market demands with the minimum attention paid to exploration. Mechanization of the mine and the pressure for sustained high tonnages since 1955 have emphasized the importance of an expanded exploration and development programme.A serious handicap has been the impossibility of utilizing normal diamond drilling methods to explore ore conditions in advance of mining faces. Drilling between tl1e bedded zones has been done but the major difficulty has been to delineate ore reserves in the lower bed, which has the greatest ore potential of the three mineable seams."

Jan 1, 1960

By P. C. McLeod

THE GECO OREBODY, located north of lake Superior in the Thunder Bay district of northern' Ontario, was discovered in 1953. Diamond drilling in the following year indicated a 15,000,000-ton ore-body, and production plans were made for the shipment of copper and zinc concentrates in three years. To accomplish this, the Geco Project was initiated. The property was in an undevdoped, inaccessible area, and the project involved the conversion and extension of a logging road to the property, the construction of two railways and seventy miles of hydro transmission line, the erection of a municipality, the building of a plant, and the development of an underground mine to produce 3,300 tons per day. This paper describes some of the methods used in the underground development phase of the Geco Project.

Jan 1, 1958

In this study, flotation of fine galena, chalcopyrite and pyrite was performed after grinding with different extent of oxidation-reduction condition adjusted by grinding media. Sodium dithionite and iron ions were added in mill to simulate pulp potentials and iron oxidation species produced by grinding media, respectively. The types and quantities of the metal oxidation species on mineral surfaces were determined by EDTA extractions, while the surface electrical properties of minerals and interaction of different types of metal oxidation species were studied by zeta potential measurements. It was found that the nature and concentration of the absorbed metal oxidation species were dependent on oxidation atmosphere controlled by the iron amount of grinding media. These species interacted with each other and had an important role in determining flotation of fine galena and chalcopyrite as well as activation of fine pyrite by lead and copper.

Jan 1, 2006

By Thomas C. Poulter

Abstract The Poulter seismic method of geophysical exploration is an attempt to obtain an increased efficiency in the conversion of the energy of an m~pl06ion into useful energy which has directive properties and which contains a minimum of random frequency and random phase relations. Very little effort has been made in the past to simplify OT even control the uniformity of the seismic energy being introduced into the ground. The Poulter seismic method is also an attempt to improve the signal-to-noise ratio not merely by trying to complete the impartial filtering done by the earth on ,the continuous spectrum of primarily high-frequency energy radiated from a shot point but by applying a frequency control at the point of origin of the seismic wave. The energy from a shot-hole charge is peaked in a frequency which is much higher than will be transmitted through the ground, and its absorption introduces background interference. Only 10 to 20 per cent of the seismic energy of a shot-hole charge .is directed downward in a 90-degree vertical cone, whereas, from a pattern of charges detonated above the surface of the ground, 85 per cent of the seismic energy is included in a 90-degree cone and in some cases it is even confined to as small as a 30-degree cone. This greatly reduces the horizontally distributed energy, thereby producing a marked improvement in the signal-to-noise ratio. The frequency of the signal energy may be peaked in a rather narrow range by the proper application of two or more impulses upon the surface of the ground controlled as to direction, magnitude, and timing. These impulses may be controlled by the reflection shock wave technique, the pressure pulse technique, and the sequence firing technique, using the primary controls as outlined. The information obtained from the study of directivity of seismic energy in a high velocity, uniform material such as the ice on Taku glacier, in the Juneau ice field in Alaska, has been of great assistance in the application of the method to oilfield and mining problems.

Jan 1, 1950

By P. Dent

"Rare earth permanent magnets (REPM) have become virtually indispensible in hundreds of applications including aerospace, automotive, electronics, energy, medical and military. An understanding of REPMs is important since they are key drivers of demand for the overall rare earth sector. Rare earth permanent magnets stand out due to their superior magnetic properties of high induction and coercive force. We will discuss the past, current and future of the permanent magnet market and supply chain. We will summarize present and potential new nanocomposite and lower content or non rare earth magnet technologies and customer options which may mitigate rare earth usage.INTRODUCTIONRare earth permanent magnets are ubiquitous and often unseen critical components in many civilian, green energy and military technologies. They have become imbedded in applications such as hybrid electric vehicles, computer hard drives, direct-drive high power wind generators, audio speakers, motors, energy conversion systems, most weapons systems and hundreds of other uses. Several rare earth elements including neodymium, samarium, dysprosium, praseodymium, terbium and gadolinium are essential ingredients in production of the highest performance magnets available in the world today. They have enabled vast miniaturization and the significant increase in power density in hundreds of applications.China has become the dominant source of rare earth elements over the last two decades. Today, nearly 100 percent of the world’s rare earth metals and more than 95 percent of the rare earth oxides come from China. China’s near worldwide monopoly on the production of downstream materials such as rare earth oxides, metals and magnets severely impacts the supply chain in this growing global market. The past decade has seen an unmistakable trend toward increased dominance in raw material production and manufacturing by China, and a steep decline in U.S. production capabilities, most notably in the neodymium iron boron (Nd-Fe-B) market where there is currently no domestic production. This Chinese dominance is further demonstrated with over 65 percent of hard ferrite and roughly half of aluminum nickel cobalt (Alnico) and samarium cobalt (Sm-Co) production in that nation (Figure 1). In addition, China has imposed export quotas and export taxes of up to 25 percent for rare earth elements, arguably in violation of their covenants made with their protocol of accession to the Word Trade Organization. These export quotas have been decreasing steadily over the last several years in spite of rising global demand and were slashed by 72 percent in July 2010 (Bradsher, 2010) causing many recent news stories."

Jan 1, 2012

By Candido Bariáin

A new vapochromic material of formula [Au2Ag2(C6F5)4(bipy)2]n (bipy = 2,2´ bipyridine) has been developed and used for the detection of some volatile organic compounds as acetone either in vapour or in water solution. The material is presented in the form of powders which colour changes with acetone vapours turning from bright yellow in the absence of vapour to white in the presence of vapour. By using the sol-gel technique, the powder ? dispersed in tetraethyl orthosilicate- was easily deposited on optical fibres. In order to study experimentally the behaviour of this material for construction practical optical fibre sensors, a sol-gel material doped with the vapochromic material is deposited onto an extreme of a monomode fibre connected to a coupler. The behaviour of the material was studied for different wavelengths and concentrations of acetone vapours and acetone/water solutions. Changes up to 4dB in the reflected optical power were detected. Optical fibre sensors have many advantages over conventional ones, such as electromagnetic interference immunity, passivity behaviour, possibility of using multiplexation techniques, low weigh and little size, etc. Actually, there is an increasing interest in developing optical fibre sensor for vapour detection in the chemical industry and in fact many sensor had been developed [1]. Some are based on the deposition of a sol-gel-based material either over the core of an optical fibre [1] or onto the thinner zone of a biconically tapered optical fibre [2]. Others are based on Fabry-Perot interferometers [3]. Also there are sensors based on the reflection of the light on films, on the fluorescence of dye-doped polymer cladding in fibre, on colorimetric reagents in the core of a silica fibre or on surface plasmon [4]. The possible materials for the construction of such sensor should be colorimetric reagents able to change the colour or refractive index in the presence of same organic vapours. There are not many metallic complexes with these properties, although same interesting examples have been reported in the chemistry of palladium and platinum as [Pt(p-R-C6H4NC)4][Pd(CN)4] described by Nagel [5] and Mann [6], which reported the construction of some LEDs. We recently reported the preparation of a novel vapochromic material (Fig 1) [7] which can be used for the construction of optical fibre tapered environmental sensors [8,9] of vapour organic compounds (VOC´s). Also we reported other nickel and palladium derivatives which present this type of behaviour [10]

Oct 1, 2003

By C. A. Ingram

The Cigar Lake ore body is a high-grade uranium deposit situated within water-saturated sandstone. In order to extract the uranium ore remotely, ensuring minimal radiation dose to workers, and also to access the ore from stable ground, the Jet Boring System (JBS) was developed. This method of mining involves drilling a pilot hole up through a frozen ore body and utilizing a high-powered water jet to mine out cavities. During the mining process an ultrasonic sensor will be used to provide feedback to the operator, who is located beneath the ore body, as to the dimensions of the cavity. However, more precise data is required to determine final shape, volume, and location of the cavity for mine planning purposes. Selecting a device that will provide sufficient range data in the challenging environment will be vital to optimizing the mining process. Major issues include fog build up and flying debris during mining, and an environment that is wet, dark, and cold A test cavity has been designed and constructed at the Saskatchewan Research Council (SRC) so that a study comparing three different technologies, as prospective candidates for the survey system, can be conducted. The devices being evaluated include a Senix ultrasonic sensor, an MDL Cavity Auto-Scanning Laser System (C-ALS), and a MESA Time of Flight (ToF) camera. The ultrasonic sensor is known to provide range data in foggy conditions but has low accuracy. The C-ALS has been developed for surveying remote cavities but is expensive and does not provide reliable data in fog. The ToF camera provides a high volume of data in a short time period, with potential to provide accurate information in extreme conditions, but has not been tested in a mine cavity application. Iterative closest point (ICP) registration is applied in an attempt to create a 3D point cloud from the scan data and to also compute rotation and translation of the ToF camera. This paper presents an overview of the challenges involved in conducting a survey within a JBS mined cavity, the analysis used to determine the suitability of each device, and the data collected from the test cavity.

Aug 1, 2013

By D. Moronkeji, R. Maharidge, D. A. Curry, B. J. Davis, U. Prasad, J. Franquet

"Proper shale characterization is crucial in shale gas drilling, exploration, completion and production. Unlike porous sandstone and carbonate reservoirs, the challenge with shales comes from their micro- to nano-darcy permeability ranges and the anisotropy of their mechanical and hydraulic properties. Most porosity-dependent logs are not sensitive enough to capture the true behavior of shales. Consequently, mineralogy and other strength and stiffness-related properties must be determined to characterize magnitudes and variances in shale mechanical and flow properties. In addition, these properties must pass quality assurance/quality control (QA/QC) practices to give confidence in their use in subsequent log calibrations, during geomechanical modeling, or in fracture design models. This paper presents a technique to integrate shale properties that are measured by various methods, and a methodology to perform QA/QC on the data before application.Shale properties originate from various sources, including downhole and laboratory measurements. Physical samples for laboratory testing are usually limited to a few depths. Lab tests are often costly, and replicating in-situ conditions can be difficult or impossible. In addition, results frequently show wide scatter, reflecting inherent depth variability and lateral heterogeneity. Wireline logs provide nearcontinuous data, but rarely yield direct measurements of rock strength properties. Although geomechanical and fracture models use log data, calibrating it with reliable and previously verified lab-measured properties is important. This paper presents a process to perform QA/QC on lab-measured data using various crossplots.Ten mechanical, microstructural and physical properties are graphically displayed to visually characterize shale strength behavior in ambient and in-situ conditions, whether measured or modeled statically or dynamically. These properties are often sourced from different departments. The properties are integrated but are individually subject to the previously mentioned uncertainties. Pairs of property values are crossplotted and compared with correlations from the literature or previously established with qualified data from related formations. Conformance with these correlations gives confidence in the data, whereas outliers are flagged as questionable. Repeating the process with questionable data crossplotted against other parameters for the same depth highlights the property with the greatest uncertainty. The determination of its value is investigated to locate the source of the inconsistency and establish a more reliable value. Where this is not possible, the user has a rational basis for rejecting that property value."

Jan 1, 2015

By D. F. Coates

Slope problems arise on mining properties from cuts for roads and railroads and from open pits. When it is 'realized that 1,000,000 extra tons of waste may have to be mined as a result of an average slope being reduced by 1 ° it is easy to appreciate that the slope problems connected with open pits are of far greater importance than the others. The type of slope failure that can occur can be classified in different ways. The most useful classification would be one that separates the causes in such a way as to provide a basis for studies to deal with problems of prevention and control. Using this criterion the types of slope failures are classified into four groups. Having classified the problems in this way an understanding can be gained of the various mechanisms involved in failure ..

Jan 1, 1961

By Knud Sinding

Many industries have established their own systems for self-regulation. They often do so when companies operate in countries where financial, technical, environmental and social regulation is weak and when the industry is challenged by legitimacy issues related to behaviour in one of these areas. Mining is one industry that has progressed unevenly down the road of self-regulation in these areas. This paper examines how the development of self-regulation for mines and mining companies involves difficult questions of scope, rules, membership, assessment criteria and performance evaluation. Using a range of theoretical and empirical results from research on self-regulation, performance rating and corporate strategy, this paper analyses the strategic and operational issues related to the idea of self-regulation in the mining industry. The analysis indicates that while self-regulation may bring benefits to members, they are likely to take a long time coming; but when they do arrive they may be substantial. Using the fact that in relation to technical and financial issues the industry is quite experienced in self-regulation ? not least as it is more reluctant in areas such as environmental and social performance ? the case is made for a comprehensive and innovative approach, that draws on the areas where the industry is experienced and develops new institutional solutions in the areas where the industry is more reluctant.

Aug 1, 2013

By M. A. T. Cocquerel, J. G. Eacott

"Simulation techniques may be used to optimize existing processes and plant operations, and in plant design at the engineering study stage of a project . This paper describes the latter application, using a computer, to optimize the concentrate stockpile requirements of a modern copper smelter.A large open-pit mining operation is envisaged and it is assumed that copper concentrate is smelted in two flash furnaces. The proposed mining plan gives rise to metaffurgical considerations in smelting which dictate that concentrate blending is carried out in the early years of operation in order to eliminate wide variations in the grade of concentrate charged to the furnaces . Stockpiling facilities are therefore necessary for blending purposes and also to provide a strategic reserve of concentrate to ensure continuity of concentrator and smelting operations.The objective of the study is to determine the optimum size of concentrate stockpile required to take account of both metaffurgical and strategic considerations. Two separate simulation models are developed to achieve this objective. The first model is used to determine the minimum size of stockpile necessary for blending purposes to smooth out variations in concentrate grade between 15 - 60% Cu, with associated 34 6% Fe, respectively, and ensure that the concentrate fed to the furnaces does not faff below 12% Fe, which is considered a minimum for good smeltability.The second simulation model covers a projected three-year operating period and indicates the maximum size of stockpile which is likely to develop during scheduled and unscheduled shutdown periods in the concentrator and smelter.Covered storage volume and conveying facilities for the optimum size of concentrate stockpile can be designed based on the results generated by the simulation models."

Jan 1, 1980

By W. G. Brissenden

"ALTHOUGH I SHOULD FIRST REVIEW the state of the mining art as it is today, because of the shortness of time I will confine myself to a re-view of the more important advances in that art which have been made in the past two to three decades. Then, a look at the opportunities and the challenges which now present themselves will be more meaningfulFirst, some of the more impor-tant developments in underground mining:(1) The recognition that good ventilation, visibility and working conditions are essential preliminaries to efficient production has resulted in their incorporation as a matter of practice in modern mine planning. (2) The introduction of the car-bide bit and the re-introduction of the airleg drill, and the resulting sharp rise in productivity, were early postwar developments. (3) The recovery of the coarser fraction of mill tailings for use as mine backfill also is an important cost-reducing development of recent years -and this has led to cemented backfill, which, al-though more expensive, meets certain specific needs and has tremendous potential. (4) Great strides have been made in improving explosives' materials and explosives' accessories. Millisecond-delay electric blasting caps, which improve fragmentation and reduce the seismic effect of blasting, and the development and •application for underground use of explosives are but two among many such improvements. (5) Trackless mining methods, using quarry-type equipment in some instances and specially de-signed low-headroom trucks, loaders and carrier-mounted drills in others have been successfully applied. (6) Dual-purpose load-haul units are now in use loading and hauling from open stope drawpoints, and smaller versions of this type of unit are in use in cut-and-fill and other types of stopes."

Jan 1, 1968

By G. E. Murray

Introduction The development of the method for recovering zinc from lead blast-furnace slags at Trail is interesting and important in the history of both lead and zinc metallurgy. Many efforts have been made in the past, particularly in Germany, to make economic recovery of zinc from slag. The Pape process on Oker slags was successful and is being worked at the present time. More recently the Waelz process has come to the fore. One effort at Cockle Creek, Australia is of special interest in view of subsequent developments. This was re-ported in detail by Guy Courtney in 1920(1). It deserves mention as it shows how, as in many other instances in the metallurgy of lead and zinc, important pioneering work has been done in Australia. These experiments, started over 25 years ago, comprised reduction with coke, powdered coal, and eletrothermically in carbon-lined furnaces. The so-called slag eye furnace, which volatilised the metals from a blast furnace running with a hot top, was also investigated.

Jan 1, 1933

By J. Kramer, T. Hartmann

In the Hydrometallurgical processes, the presence of the so-called “crud” is a constant challenge in solvent extraction. Crud is a stable emulsion which forms along the interface between the aqueous and organic phase. The spread is influenced by the following parameters: first, wind blows the dust and impurities into the open sedimentation tanks. Second, the undissolved solids such as sand transported in the PLS causing problems in conjunction with incorrect agitator design. The crud fraction can decisively impact the efficiency of the hydrometallurgical extraction because the phase interface can constitute a large fraction and the sedimentation tanks cannot react flexibly to it. In the downstream process of the seriesconnected sedimentation tanks, they are thus all contaminated with crud. At the same time, the necessary mass transport is significantly impeded at the phase boundary between organic phase and aqueous phase due to the crud formation. The transfer of the organic phase into the electrolysis cell can result in a “burnout” of the cathode. The carry-over of this electrolyte into the extraction can cause problems with the pH regulation. The carry-over of the organic components into the raffinate also leads to contamination of the leaching circuit. The continuous treatment of the crud with a 3-phase decanter centrifuge is extremely effective in combating this problem. This technology splits all three phases from each other and they are consequently continuously separated. All subsequent process steps exhibit a stable, uniform effectiveness. The main advantage for the customer is that fluctuations in the process are eliminated and the organic phase can be recirculated back to the extraction. The recycling of the solvent alone justifies the investment in less than 6 months as examples from South Africa and Chile show. To operate solvent recovery in daily operation fully automated online at the optimum limit, the decanter centrifuge is equipped with a concentration-dependent pond adjustment called DControl®. By this means, we can guarantee our customers the maximum possible solvent recovery and minimise the solvent costs in this process step. This system is presented in detail in this paper.

Jan 1, 2012