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By T. Kalliomäki, A. T. Aji, M. Lundström, J. Aromaa

The settling properties of anode slime in copper electrorefining have crucial effect on copper cathode quality. Anode slime settling is affected by electrolyte composition and temperature, electrolyte circulation, and the sizes and density of the slime particles and agglomerates. Typically, the industrial copper electrolytes contain 40–60 g/dm3 Cu2+, 130–220 g/dm3 H2SO4, 0.04–25 g/dm3 Ni2+, 0.005–30 g/dm3 As, and have operating temperature of 55–70°C. In optimal electrorefining process, the settling rate of anode slime is sufficiently high to avoid the risk of getting the slime entrapped in copper cathodes. In this research the settling properties of copper electrorefining bottom slimes, mainly consisting of Cu, Ni, Ag, Se, Pb, As, Bi, Sb and Ba compounds, were studied by settling rate tests. The tests were conducted in water and synthetic electrolytes with known viscosities and densities. In addition, the effect of agglomeration was taken into account – it was observed that breaking the agglomerates which existed in the as-received slimes decreased the particle sizes on average 56–73%, which decreased the settling rate. The results of this study provide detailed information of anode slime settling and thus clarify the conditions causing cathode contamination risks in copper electrorefining. INTRODUCTION Settling rates of Cu-ER anode slimes affect the purity of cathode copper and faster settling rate decreases the contamination risk (Davenport et al., 2002; Shi & Ye, 2013). The settling rates are affected by the properties of anode slime particles (Wills & Napier-Munn, 2011; Aaltonen, 2014; Kiviluoma, Aaltonen, Aromaa, Lundström & Forsén, 2016) as well as viscosity and density of the electrolyte (Davenport, King, Schlesinger, Biswas, & Robinson, 2002; Shi & Ye, 2013). Thus, it is crucial to find out how the viscosity and density affect the settling rates. Small spherical particles with diameter below approximately 50 µm obey Stokes’ law (Equation 1) (Wills & Napier-Munn, 2011). v = gd 2 (ρS – ρF) (18η) -1 (1) where v is terminal velocity (m/s), g acceleration due to gravity (m/s2), d diameter of particle (m), ρS density of particle (kg/m3), ρF density of fluid (kg/m3), and η dynamic viscosity (Pa∙s). The approximate effects of kinematic viscosity (ν = η / ρS), density (ρS) and particle sizes on settling rates defined for small anode slime particles based on Stokes’ law are presented in Figure 1. However, Stokes’ law does not take into account other than spherical shapes, and it is only applicable for small particles. Consequently, the real settling rates of the particles are lower than these (Wills & Napier-Munn, 2011). Moreover, some of the anode slime particles are larger than 50 µm (Aaltonen, 2014).

Jan 1, 2019

By S. Surapunt, C. M. Nyamai, K. Itagaki

"The use of liquid copper as a medium for zinc extraction has been used in the Warner Process as a method of processing zinc-lead sulphide ore. The recovery of zinc metal is based on the reaction:ZnS(s) + 2Cu(l) = Zn(g) + Cu2S(l)In this method, thermodynamic and phase equilibria investigations of the Cu2S-FeS-ZnS and Cu2S-PbS-ZnS systems are of importance and form the basis for the liquid sulphide phase which appears as a product and is used as a solvent in the Warner Process. Phase relations in the Cu2S-FeS-ZnS and Cu2S-PbS-ZnS ternary systems were determined experimentally at 1473°K to provide a fundamental basis for the new zinc smelting process. The results show that the solid solubility of ZnS in the two systems is very small (2 wt% to 3 wt% ZnS in FeS, 4 wt% ZnS in Cu2S for the Cu2S-FeS-ZnS system; less than 0.5 wt% ZnS in both PbS and Cu2S for the Cu2S-PbS-ZnS system). The Raoultian Activity Coefficient of ZnS in the liquid mixtures and the vapour pressure of zinc over the matte in both systems is relatively large (?° = 7.7 – 15.8, Pzn(atm) = 0.088 – 1.026 for the Cu2S-FeS-ZnS system; ?° = 8.9 – 12.9, PZn(atm) = 0.075 – 0.214 for the Cu2S-PbS-ZnS system). On the FeS-ZnS join, the only phases detected are FeS and iron-rich sphalerite (Zn, Fe)S. The binary join mixture occurs at about 92 wt% FeS-8 wt% ZnS at 1473°K. Electron microprobe examination of the quenched samples indicate about 47 wt% to 48 wt% FeS in sphalerite and about 2 wt% to 3 wt% ZnS in the iron sulphide phase. On the Cu2S-ZnS join, microprobe analysis reveals that the maximum solubility is 4 wt% Zn in liquid Cu2S and 3.6 wt% Cu in solid ZnS. In the Cu2S-PbS-ZnS ternary system, microprobe analysis of the quenched samples indicate on average, 5 wt% ZnS in the liquid phase region. The only phases detected on the PbS- ZnS join are ZnS and PbS. The eutectic phase contains, on average, 13 wt% ZnS. The phase relationships, very low solid solubilities of zinc sulphide in the liquid mixtures of both Cu2S-FeS-ZnS and Cu2S-PbS-ZnS systems, coupled with the high Raoultian Activity Coefficient of ZnS as well as the high vapour pressure of zinc over matte all favour the partitioning of zinc metal into the vapour phase. This new process is cost effective and bypassesthe expensive and tedious conventionaltechnique of zinc production involving oxidationof the sulphide ore by roasting followed bya reduction process to extract the zinc. Theresults indicate that a new zinc smelting technologyusing the Warner Process would bemore efficient and preferable over the traditionalmethods of zinc extraction."

Jan 1, 2002

By John J. Deutsch

"1T is a great pleasure for me to be present at the Annual Dinner of the C.I.M.; a pleasure which is combined with a mutual opportunity that I value highly. First of all, this occasion gives me a chance to meet again many Members of your Institute and to become more fully informed of the special problems of the mining industry. This alone is ample reason for me to welcome the invitation to join you tonight. In addition, this occasion provides me with an opportunity to tell you something about the work of the Economic Council which might be of particular interest to your industry.In the mining industry, keen competition and constant change are basic facts of life. The continuing prosperity of the Canadian mining industry depends fundamentally on how successfully it is able to adapt both to the changing conditions within the industry and to major trends which operate throughout the world.First of all, the scale and organization of the industry are evolving to new and different dimensions. As one authority has put it, ""The cream of the small high-grade, easy-to-mine ore deposits of this world have been consumed and mining is becoming more and more an industry of very large scale, complex operations. It has already become in most countries a capital intensive industry and its problems, scientific, technical and economic, are growing in difficulty."""

Jan 1, 1966

By T. Salman

Most authorities agree that the dissolution of gold from an ore takes place according to the Elsner equation first stated in 1846. The main requirements for the dissolution reaction to proceed are:(1) that the gold be clean.(2) that the gold be exposed to the solution.(3) that the cyanide solution be active, i.e., not over loaded with impurities which could retard or inhibit the reaction.(4) that an adequate supply of oxygen be available (from air).When the above conditions are met, cyanidation becomes basically a mechanical operation.Minerals such as quartz, calcium carbonate are relatively inert to cyanide though they may give rise to mechanical troubles. Most ores present an assortment of chemical problems, depending upon the constituent present, which react to the solution to varying degrees. It should be borne in mind that minerals which are disturbing to the operation, though present in small amounts, usually exceed the weight of the gold by several hundred times. In addition, the application of flotation and other forms of concentration to gold ores, previous to cyanidation, concentrates not only the gold, but also the other heavy minerals and these complicate the chemistry of the process.

Jan 1, 1975

By Michel Brissette

"To recover more valuable ore and considering the complexity of minerals, the needs to grind finer is increasing. To reach the desired fine grinding targets, using the existing grinding media size, the energy consumption is increasing exponentially. As already proved at this conference, small grinding media represents the best potential to improve grinding efficiency. How do the small grinding media perform in industrial grinding mills?The use of small grinding media in regrind mills proved that finer grinding can be achieved at lower energy consumption. In ball mills, smaller grinding media versus 25 mm media generate a power saving from 10% to 44%. In vertical stirred mills, the power saving increases from 20% to 60%. More potential savings have been identified.For the same operating conditions, how a vertical stirred mill is performing compared to ball milling? In regrind application, a vertical stirred mill with small media (5-12 mm Millpebs) will require at least 62% less energy than a ball mill charged with 25 mm grinding media.INTRODUCTIONIn some mining applications, fine grinding is needed to liberate further the valuable ore. The purpose of regrind mills is to achieve the last stage of grinding before final flotation stage: the cleaners. In part because of high prices of small grinding media as well as availability, the most widely used size of grinding media is 25 mm.When calculating the recommended ball top size from Bond’s formula (Bond, 1961), the size for regrind applications is much lower than 25 mm. Today, the barrier for small grinding media is broken. They are best suited in regrind application. The size of grinding media is one of the most important variables affecting the mill efficiency (McIvor, R., 1997; Nesset, J.E., Radziszewski, P., Hardie, C. & Leroux, D.P., 2006).Conventional ball milling was discarded for fine grinding because of its very poor energy efficiency (Zheng, J., Harris, C.C. & Somasundaran, P., 1994; Yan, D.S., Freeman, M. & Dunne, R., 1995). Therefore, new technologies as stirred mills were developed to grind finer more effectively. Three fundamental questions should be asked. What is the best fine grinding technology? What should be the best media size to use? Is it possible to grind finer by using less energy with the existing regrind equipment?"

Jan 1, 2009

By G. S. Barry

INVESTIGATIONS to date have shown that, should there be the need or the appropriate economic stimulus, Canada's mineral resources are sufficiently extensive to allow considerable expansion of its non-fuel mineral industry, during the remaining part of this century and possibly beyond (1, 2). The availability of sufficient capital will be one of the critical factors which will determine whether this potential will be fulfilled. The following analysis centers on the capital requirements of the Canadian non-fuel mineral industry under one set of basic assumptions of capacity growth, cost of new and replacement capacity, rates of depletion and depreciation of mines and plant, and the cost of exploration and infrastructure. Mindful of the fact that exploration and development will not thrive in Canada unless a very positive approach is taken, the writers make no apologies for being "optimistic" about long-term production prospects. Furthermore, in the event that world demand does escalate as anticipated and the forecast realistically attainable levels of Canadian production are not reached, then Canada will not have reaped the full range of economic benefits available, and opportunities will have been lost. Projections for Canadian production between 1976 and 2000 are essentially based on the forecast published in the 1974 paper, "Towards a Mineral Policy for Canada - Opportunities for Choice (3), with some updating on the basis of recent developments.

Jan 1, 1977

By John Loop, W. A. Gibbins, Donald D. Hogarth

"Introduction Background The Frobisher voyages of 1577 and 1578 were organized by the Cathay Company for the express purpose of finding and mining gold ore. Since publication of the Baffm expedition of Charles Francis Hallill, the location of Kodlunarn or Countess of Warwick Island, the headquarters of Frobisher's third (1578) voyage, and focal point of the largest Arctic voyage of all time, has been known to the world. Through Hall we also know the location of the Countess of Warwick Mine on Kodlunarn Island. However, the exact locations of the other mines are not known. Of the ""ore"" we know little. Pieces of the original ""black stone"", once as large as ""a half-penny loaf' have now disappeared altogether. Specimens collected at random from the repository of shipments in England and from loose rock on Kodlunarn Island were termed, respectively, ""hornblende pyroxenite"" and ""amphibolite"" and from a locale about 200 yards from Kodlunarn as (hornblende) ""pyroxenite""121. However, it is uncertain whether these specimens are representative of Kodlunarn or of the other mines, although Blackadar131 notes that, in the northern trench of Kodlunarn, biotite gneiss contains lenses and bands of amphibolite. The ""gold"" itself is even less well defined. It has long been accepted that gold was virtually absent in Frobisher's ore. The ""gold"" has been termed pyrite, biotite and both biotite and pyrite together. Even t h e word "" marquesset"" , which appears and reappears in contemporary descriptions, is nebulous and is defined as ""a stone participating in the nature of some metal, yet in so small quantity, that the metal cannot be melted from it"" (0.E.D., definition of 1616)."

Jan 1, 1999

By Hyung Sup Choi

The preparation of high-purity zirconyl compounds was studied in order to develop an economical process for obtaining pure zirconium via the caustic fritting of zircon sand. The direct dissolution of caustic frits with concentrated hydrochloric or nitric acid at 80c. followed by the addition of a small amount of acidified gelatin, gave high-purity zirconyl chloride or nitrate. The addition of a small amount of gelatin caused a mutual flocculation between colloidal silica and gelatin. The precipitation of this silica floc markedly lowered the content of silica in the product. The silica content of the compounds (or solution) so produced, generally less than 100 ppm., was sufficiently low for tributyl phosphate extraction for nitrate solutions. It was found that the degree of purification de-pends not only on the procedures employed but also on the nature of the frit itself. Silica was more effectively eliminated from the fritted product produced at higher temperatures, and less silica was present in the com-pound prepared from the frit produced in a shorter heating time. In order to ascertain the nature of the

Jan 1, 1965

By J. Petit

"In July 2004 workers at the ABI Smelter in Bécancour (Quebec, Canada) went on strike. Contingency plan were ready to face the situation and plan was done to operate one potline out of three. Two lines were stopped; keeping in mind the restart on cold metal after the strike was over. The subject to be presented and shared includes a summary of work organization including training, schedule of restart, pot cleaning, pot preparation, crash start method, follow up after crash start, safety and environment. This major project has been a very big challenge. It shows that people involvement is a must and the key success. It is then true to say : ""People who believe in success will work and act in order to get there"" and ""People who don't believe in success will act in such a way to fail"" Then both will prove they were right to think their own way ! Sharing such experience can be interesting because it's a true story and people like true stories."

Jan 1, 2006

By Paul Billingsley

NICKEL Plate mountain coincides closely with that portion of the Hedley mining district which is of economic interest. From it has come almost the entire past production, and the active mines of the present epoch, Nickel Plate-Sunnyside and Hedley Mascot, lie in a compact group near its summit. The Hedley district, which is 210 miles due east of Vancouver, is situated in the Okanagan range of southern British Columbia, where this rather gentle uplift is deeply dissected by the canyons of the Similkameen and its tributaries. The region is essentially part of the Interior Plateau of the Province (Figure 1), but is adjacent to easterly elements of the Coast Range. The Similkameen canyon, 4,000 feet in depth and frequently less than 4 miles from rim to rim, traverses the district from northwest to southeast. The deepest and narrowest portion of the canyon lies between Hedley and Keremeos, 18 miles to the southeast. At Hedley, an important tributary, Twenty Mile creek, enters from the north in a bold canyon, making a focus of unusually rugged topography. Nickel Plate mountain occupies the sector to the east of this junction (see Figure 2) and its flanks are ringed by the cliffs of Twenty Mile canyon on the west and by those of the Similkameen canyon on the south. On the east, it slopes gently to the hanging valley of Eighteen Mile creek, and on the north, with only slight loss of elevation, it merges into the moderately hilly surface of the plateau.

Jan 1, 1941

By J. Chlan

"Dryer DescriptionProctor and Schwartz Continuous Conveyor DryerThe Proctor and Schwartz Continuous Conveyor Dryer has been in operation since July 1958, and comprises six unit• - an 8• wide single conveyor with roller extruder, insulated housing, type 304 stainless steel circulating and exhaust fall system, steam heating coils, temperature controls and discharge crusher rolls. Entire dryer dimensions are 52’ x 12'0""weighing 53,000 lbs,Extruder rolls - setting is 1/8"" (Drive 3 HP 1800 RPM) clearance off the extruder screen.Conveyor - consists of 151 interlocking pans, measuring 8"" x 8' (2 HP 1200 RPM) One Exhaust Fan (5HP - 900 RPM)Steam Coils -- l"" steel pipe - with steel fins -- each coil measures 16' 2’’- 64 coils in the No, 1 Compartment- 64 coils in the No, 2 CompartmentDryer OperationThe yellowcake slurry at 28% solids is pumped to an 81 x 8' Peterson Filter. The filter media presently being used is a Neotex 4372 blanket, being 100% staple fibre nylon, 12 oz per square yard with air porosity of 9 CFM's. The cake discharge at 45 - 50% moisture falls into the roller extruder. Extrusions are formed by forcing the material by rolls through a perforated plate moving back and forth and depositing the spaghetti-like extrusion on onto the dryer-conveyor.The conveyor now carries the extruded material through the heating chamber•, The feed end of the dryer will be referred to as No. 1 Compartment, with temperature control set at 280""F. The circulating fans take the hot air off the coils and circulate the heated air through the perforated openings in the dryer conveyor pane, After passing through the set of steam coils and circulating fan in No, 1 Compartment, the material then goes through No, 2 Compartment where the temperature is set at 305'F, Final material then discharges through a set of crusher rolls set at ~"". Moisture of final dried product runs at less than 2%.The dryer conveyor load is usually run to a 3"" - 4"" depth load. Conveyor speed at approximately 90 minutes for load to pass through. Load onto the conveyor is controlled by boot level and speed of the 8' x 8' filter. The dryer steam coils are water-washed twice a month."

Jan 1, 1972

By Douglas E. Wolfe, Jogender Singh, Robert Miller, Dong-Ming Zhu, Jeff Eldridge

This paper discusses microstructural changes produced by two novel approaches using electron beam physical vapor deposition (EB-PVD) in which periodic strain fields/microporosity was incorporated within the large columnar grains of Zr02- 8wt.%Y2O3 (8YSZ). The traditional columnar microstructure of partially stabilized zirconia has been slightly modified to produce a lower thermal conductive thermal barrier coating (TBC) by periodically interrupting the condensing vapor resulting in microstructural modifications with diffuse or sharp interfaces and morphological changes on the sub-micron scale without changing the composition of the TBC. These microstructural modifications resulted in a 20-30% reduction in the thermal conductivity, 28-56% increase in hemispherical reflectance, improved oxidation cyclic life (over 100%), and better strain tolerance as compared to standard ZrO2-8wt.%Y2O3 deposited on platinum-nickel-aluminide and CoNiCrA1Y bond-coated MAR-M-247 test samples. The TBC with tailored microstructures were examined by various techniques including scanning electron microscopy (SEM), x-ray diffraction (XRD), steady-state laser heat flux technique, and hemispherical reflectance.

Jan 1, 2004

By Eugene (Gene) Bounds

The Mining industry faces many challenges, one of which is the demand to communicate over a variety of media, be it visual, sound, voice, data or any combination. Over the years multiple infrastructures have been put in place to overcome environmental obstacles and address these communication needs. A mine is an aggressive environment for electronic equipment and as such only the best quality equipment can perform under those special conditions of e.g. temperature, dust and humidity. Siemens Canada and its partner LComm will discuss a mining solution using a unique combination of technologies based on fibre optics, standard communication interfaces, passive antenna infrastructure and wireless services. The presentation looks at maximizing the use of infrastructure, reducing costs, addressing difficulty of communications coverage above and below the surface and the capability to future proof the capital investment as new requirements and applications are identified. Discussion will address: Wireless voice, high speed data Data acquisition for process control from sensors Video for remote control and security Miner safety and location Timely receipt of large volumes of information

Apr 1, 2005

By C. Desmeules

"Carbon addition in the oxide pelletizing process is a big concern at the Sidbec-Normines pelletizing plant since 1976.Laboratory pot-grate testing carried out before the initial start-up of the Port-Cartier plant indicated that the nominal pelletizing grate capacity could be increased by fifteen per cent with a suitable carbon addition. Also an improved induration cycle offered the possibility of a significant energy reduction within the process with no adverse effect on pellet quality. A one-month plant scale program duplicated the lab test results and confirmed the anticipated cost saving by using these techniques. Since March 1980, Sidbec-Normines used coke addition as a current operation.This paper reviews briefly earlier laboratory and in-plant test work carried out to investigate the effects of adding carbon materials to the Fire Lake hematite concentrate, and presents operation techniques and plant results of carbon addition in the Port -Cattier pellet plant.IntroductionThe Sidbec-Normines pelletizing plant at Port-Cartier, Quebec, is designed to produce six million ton s per year of oxide pellet s. It is a Dravo-built two-line plant; one line to produce three million s tons per year of blast furnace grade pellets averaging 5.5 per cent silica, and another line of three million ton s to produce direct reduction grade pellets of about 2.0 percent silica.The laboratory pot-grate test program was conducted in 1977 at the British Steel Corporation Research Laboratories in England, with the assistance of J .E. Appleby, consultant to British Steel Corporation (overseas services) Limited.The purpose of that test program was to determine the optimum energy saving cycle and to study the physical and metallurgical effects on blast furnace and direct reduction pellets."

Jan 1, 1983

By Ana Adé

The use of gold compounds in homogeneous catalysed organic reactions has been undervalued for many years due to the preconceived opinion that gold is an expensive and extremely chemically inert metal. However, recent reports have changed this assessment and gold salts in small amounts are known to display high catalytic activity.[1] Thus, it has been reported recently that anhydrous AuCl3 catalyses the formation of C-C and C-O bonds (usually mediated by hydrochloric and other protonic and Lewis acids).[2] Some examples include Michael type additions, selective cross cycloisomerisation/dimerisation of propargyl or allenyl ketones, benzannulation between o-alkynylbenzaldehides and alkynes or cyclisation of alkenyl furans. It is noteworthy that some of these reactions[2a] can be also catalysed by silver salts but with much lower yields. The 1,3-dipolar cycloaddition of nitrones to alkenes is a powerful synthetic method that has found numerous applications in the synthesis of a variety of carbon frameworks.[3] Several laboratories have focused on the development of Lewis acidic reagents to modulate the selectivity of the reaction.[4] Despite the extensive study performed, there are not many examples in which a metallic complex catalyses the dipolar cycloaddition. Most of these reactions require the presence of a metallic complex and nitrone in a 1:1 molar ratio. Recently, we have carried out stoichiometric reactions of the N-benzil-C(2-pyridil)nitrone, 1, with different dipolarophiles in the presence of zinc and silver compounds.[5] Apart from an increase of the reaction rate and the selective formation of one of the possible isomers, we have shown the formation of zinc and silver-nitrone complexes during the reaction, which behave as the intermediates in the cycloaddition process. As suggested by the results obtained with silver complexes, we decided to test gold derivatives (in the oxidation states of I and III). Interestingly, we have found that they can be used not only as stoichiometric reagents but they can also mediate these cycloadditions in catalytic amounts (5 to 10 mol % respect to the nitrone). Here we present the results on the 1,3-dipolar cycloaddition reaction of the N-benzil-C(2-pyridil)nitrone (2-PyBN), 1, and methylacrilate, 2, (Eq. 1) catalysed by gold(III) derivatives.

Oct 1, 2003

By Nelson Hogg

"THE NOR-ACME gold mine is located close to the north shore of Snow Lake, at 54°53' north latitude and 100°03' west longitude. It is about 75 air miles east of Flin Flon, and 36 miles by road from Wekusko at Mile 81 from The Pas on the Hudson Bay Railway.The claims which contain the Nor-Acme orebodies were staked in 1927 by C. R. Parres, who, with his sons, held the ground until 1938 when Nor-Acme Mines Limited was incorporated. In 194 l, on the recommendation of F. Ebbutt (1), this property was optioned by the Howe Sound Exploration Company, Ltd. A program of 50,000 feet of diamond drilling resulted in the outlining of two orebodies containing an estimated 5,000,000 tons with an average grade of 0.15 ounces per ton to a depth of 1,000 feet.A period of inactivity during the war years was followed by the construction of a mining plant capable of treating 2,000 tons of ore per day. Milling started in March 1949, and to the end of 1954 has resulted in the production of 383,793 ounces of gold and 32,906 ounces of silver from 3,331,403 tons of ore.General GeologyThe general geology of the Snow Lake area is described by J. M. Harrison (2), and will not be discussed here except insofar as it affects the Nor-Acme orebodies. The orebodies occur in rocks of Precambrian age that have been classified by Harrison as the Snow group, comprising meta-morphosed sediments interbedded with acid and basic volcanic rocks. The volcanic rocks include pyroclastic types which are unique in the region, a fact which led to their classification in the Snow group rather than the more widespread Missi group that generally occupies the same stratigraphic position above the Amisk group (Figure 1)."

Jan 1, 1949

By Simon C. Dominy, Alwyn E. Annels, Mark A. Noppé

Abstract - Mineral Resources and their subsequent conversion to Ore Reserves are of key importance to mining companies. Their reliable estimation is critical to both the confidence in a feasibility study, and also to the day-to-day operation of a mine. Together with sampling, assaying, geological and other errors introduced during interpretation and estimation, additional errors are likely to be introduced during the application of technical and economic parameters used for conversion of resources to reserves. There is thus a requirement for high-quality interpretation and estimation to be supported by high-quality data. Any company expecting to make sound investment or operational decisions must base this on both relevant and reliable information. An Ore Reserve statement generally contains a single set of grade and tonnage figures without a discussion of the potential inherent errors in these estimates. Some sensitivity studies may be run, but confidence limits are rarely quoted and, if they are, often do not take into account many of the factors that cause uncertainty in the grade and tonnage estimates. Mineral Resource and Ore Reserve estimates thus carry certain errors leading to uncertainty and risk; some of these are unquantifiable for various reasons, for which the operator should be aware. This paper presents a review of the potential sources of error that might occur during a resource estimation program, which are carried through into the reserve estimate. A number of methods are discussed that allow the estimator to be more transparent about the inherent risks in his/her estimate. Emphasis is placed on data quality, and the requirement for strong quality management to be linked to continuous improvement.

Jan 1, 2002

By Desmond M. Levins, Reginald K. Ryan

"Removal of radium from uranium tailings would substantially lessen their environmental impact because it would eliminate, or greatly reduce, the hazards arising from radon emanation, leaching of radium, dust dispersal and gamma radiation. A process is described to extract radium from tailings by leaching in 3M Nael solution. The radium can be rapidly leached at ambient temperatures by either multi-stage contact in agitated vessels or washing on a tailings filter cake. Extraction efficiencies ranging from 80 to 94% have been measured for tailings derived from a number of Australian ores.Methods for radium recovery from the leach solution by precipitation, ion exchange and adsorption have been examined. Precipitation as barium/radium sulphate appears to be the most suitable approach. A possible flow diagram for the process is proposed which involves recycle of the saline leach liquor.IntroductionDisposal of mill tailings is the most contentious environmental issue facing the uranium mining industry. The conventional approach to managing tailings is to store them in a dam above ground. Attempts have been made to stabilize some tailings piles by physical or chemical methods. In a few cases, the tailings have been covered with earth and revegetated. However, most tailings piles from abandoned mills are in a neglected state and subject to the erosive and dispersive forces of nature. The cost of remedial action is high. The United States Department of Energy (DOE) has estimated that it will cost up to $130 million to rehabilitate abandoned mill sites in the U.S .A..Environmental authorities are now insisting that uranium mining companies improve their methods of tailings disposal. In the United States, the preferred approach is burial, either in mines or in specially excavated pits. Tailings retention systems as operated in Canada are regarded as storage facilities until an acceptable method of disposal is found. In Australia, the Fox Commission recommended that tailings from the Ranger project should be returned to the open-cut mine. Returning tailings to the mine has considerable merit, but it is not always a viable option. In many underground operations, it is not physically possible to fit all the tailings in the worked-out mine. In other cases, the groundwater hydrology of the mine may be unfavourable."

Jan 1, 1980

By Kevin Azocar, Jim Hazzard

"Slope stability analysis is performed most commonly using limit equilibrium calculations or numerical models assuming a two-dimensional slice through an infinitely long slope surface. In areas such as open pit mining, where most slope surfaces are not planar, the importance of curvature becomes important due to the economic gains associated with creating a steeper slope. With advances in computing capabilities within the last decade, three-dimensional slope analysis can be performed within reasonable time frames. Some work has been done on the potential importance of curvature on slope stability, mainly assuming homogenous materials with a circular shear-failure mechanism. However, many open pit mines are excavated in jointed rock mass where a completely different set of failure mechanisms can be seen. Depending on the geometry and radius of the pit, the curved geometry may influence the factor of safety and failure behaviour compared to a two-dimensional slice.A series of numerical analyses were performed to investigate the effect of curvature on jointed rock slope stability compared to an equivalent two-dimensional slope analysis. By using discrete element method models, the influence of joint planes and interaction between distinct blocks can be seen. With a three-dimensional model, the effect of curvature can be combined with multiple joint sets at any orientation, which cannot be seen in a single slice. Numerous three-dimensional models are created, along with an equivalent unit-thick slice. The effect of curvature on a variety of different types of failure mechanisms is observed, and graphical relationships are created to quantify the difference between the three-dimensional factor of safety and the two-dimensional factor of safety based on the degree of curvature."

Jan 1, 2015

By J. F. Archibald

A research effort has been undertaken, under Workplace Safety and Insurance Board of Ontario (WSIB) sponsorship, to characterize the support capabilities of conventional and innovative spray-on lining materials for mitigating dynamic failure effects created by simulated rockbursts. Conventional spray support media, such as shotcrete and fibrecrete linings, and a variety of new spray-on lining materials [thin, spray-on liners (TSLs)], typically polymer-type thin coatings, were subjected to simulated rockburst influence. For baseline comparison, conventional rockbolt and bolt-and-mesh support products were also evaluated. Observation of lining performance was undertaken through completion of field-scale support and rock detonation trials. Controlled blasting tests were conducted at the Queen’s University Explosives Laboratory to examine the effectiveness of the variety of surface coating agents for modifying dynamic rock spalling processes. All tests were performed upon largely undisturbed and homogeneous rock materials in highly repeatable fashion. All blasts were observed seismically and photographically to provide detailed information concerning rock motion, surface fracturing, ejected fragment motion and support liner survivability characteristics. These material comparison trials were performed to assess the relative effectiveness of a wide range of currently available area support techniques for suppressing hazards associated with dynamic rock ejection. The results of this study validate that thin, spray-on linings may be equally as effective, and often better, than conventional support materials at mitigating rockburst or like damage in highly stressed mine environments.

Jan 1, 2004