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By Nabeel Khan

Annual oil production from the Canadian Oil Sands in Northern Alberta has been rising for several decades, and more ore and overburden are excavated each year from an increasing number of open pit mines. Overburden meeting certain specifications will be used to dam tailings and fill open pits, but the remaining material must be stored in overburden storage structures (OBSS). Well-designed overburden storage structures are more stable and cost less in the short- and long-term. The purpose of this paper is to explore OBSS designs that will be stable yet economical in the short- and long-term. The geological background of the site is briefly discussed, including the effect of each of the main geologic layers (recently deposited till and muskeg, Clearwater Formation clay shales, McMurray Formation oil sands, and the Devonian limestone) on the slope stability of the OBSS. Cost is considered in the analysis when balancing between minimizing costs (steeper slopes) and acceptable factors of safety (flatter slopes), all the while considering the financial consequences of failure. Potential failure planes are identified and probabilistic analysis is conducted on the critical failure surface. The variations in the factor of safety caused by varying pore water pressure, friction angle, and cohesion, are plotted and discussed.

Jun 1, 2012

By H. Aaltonen, T. G. Robinson, M. Morimitsu

"The energy required to plate pure zinc can be the most significant operating cost for an operator in the production of electrolytic zinc. This paper reports on developments on low energy Outotec coated titanium anode process technology with fully amorphous coatings, MSA®, and its application to brownfield zinc electrowinning operations around the world. This technology aims to reduce the operating cost and increase productivity for zinc producers.INTRODUCTIONZinc electrowinning is an energy-intensive process using more than 3,000 kWh/t of electric energy [1-4], and the reduction of the energy consumption is one of the key issues. The high energy consumption is due to a high cell voltage during electrolysis, which is mainly caused by a high overpotential of oxygen evolution reaction on lead alloy anodes which have been widely used in commercial zinc electrowinning processes. The overpotential of oxygen evolution is 0.6 V or more and which is approximately 4 times higher on average than that of the cathodic reaction (zinc deposition) [3,4]. Therefore, the reduction of oxygen overpotential is significant to reduce the electric energy consumption, and this will become more significant with increasing demand in metal production and rising energy costs.Oxide coated titanium anodes have been widely investigated for the oxygen evolution anodes in order to replace the lead alloy anodes [5-9], because it is known that the oxygen overpotential strongly depends on the material and structure of the anode. The most typical example of such anodes is an IrO2-Ta2O5 coated titanium anode, which is usually prepared at thermal decomposition of a precursor solution containing metal salts at 450 oC or more and obtained mixed oxide coating consists of crystalline IrO2 and amorphous Ta2O5. On the other hand, one of the authors of this paper, Professor Morimitsu, Doshisha University in Japan, has developed a novel oxide coated titanium anode, MSA® [10-25]. The most specialized point of MSA® is that the catalytic coatings are prepared at low thermal decomposition temperature and amorphous IrO2 or RuO2 is contained as the components in the coatings. Such amorphous coatings have high catalytic activity for oxygen evolution compared to lead alloy or crystalline coatings. Outotec acquired the international specialized MSA® patent licensing rights from Doshisha University and has produced and commercialized the amorphous oxide coated titanium anodes. These anodes have already been utilized mainly in copper electrowinning plants worldwide and have demonstrated a significant voltage reduction, a cost-efficiency, and a long lifetime. This novel technology is also effective to zinc electrowinning process, thus this paper presents the characterization and performance of amorphous IrO2-Ta2O5 coated titanium anodes and amorphous RuO2-Ta2O5 coated titanium anodes for oxygen evolution in zinc electrowinning."

Jan 1, 2016

By J. A. Herbst

It is widely recognized that Semiautogenous Grinding (SAG) circuits require the use of effective process control techniques to achieve their full processing potential and to protect them from the harmful effects of overloads and grind-outs. This requirement is even more essential as the variability of the ore being processed increases. The new Chino Mines Company concentrator located near Santa Rita, New Mexico started operation in June of 1982. At least eight major rock types are mined and milled. Ore hardness, feed size, and specific gravity are quite variable. Typical feed rates per grinding line are 850-900 tph but extremes of 260-1200 tph have been encountered. Normal feed rate variations of between 400 and 1100 tph are encountered on a weekly and sometimes daily basis. Feed size varies with rock type from a maximum of eight inches for the harder ores to two inches for the softer ores. One somewhat unique characteristic of the Santa Rita ore body among major copper mines is the wide variation in ore specific gravity. Specific gravities of the major rock types range between 2.7 and 3.6. The specific gravity variations are due to large changes in magnetite concentration throughout the pit. The result of this is large variations in SAG mill throughput which can have a harmful effect on downstream ball milling and flotation performance. Due to these wide fluctuations in ore characteristics, it was recognized soon after startup that successful operation of the grinding circuit and the plant at large was dependent upon the development of an effective automatic grinding control strategy. Research at the University of Utah has suggested that control based upon critical but difficult or costly to measure variables would improve automatic control performance. A project team made up of the Chino process control staff, Kennecott's Process Control department and the University of Utah Metallurgy Department was established to assess these concepts at Chino. This paper describes the development and on-line plant implementation of an Extended Kalman Filter that uses simple models of the SAG milling process, to predict the volumetric loading, the rock mass, the water mass, and the ball mass within the SAG mills at Chino. The on-line estimation of these parameters is the first step in the development of an integrated SAG mill/ball mill control strategy which is hoped to L eventually maintain the grinding circuit at its maximum capacity, while balancing the grinding load between the SAG and ball mills. Examples of long term estimation with the models and filter are shown for typical operating conditions as well as a SAG mill overload and grind-out.

Jan 1, 1983

By F. Rosenblum, K. E. Water, J. A. Finch, S. Moon, Y. H. Tan

Previous work has shown that sulphide self-heating occurs in three distinct stages referred to as Stage A, Stage B and Stage C. In this paper the focus is on the transition from Stage A to Stage B, which occurs at ca. 100OC. Background literature hints that the transition corresponds to the transformation of the rhombic form of elemental sulphur to the more reactive monoclinic form that occurs at 96OC. A test apparatus is modified for adiabatic heating to track the transition. The results support this transformation of sulphur as being key to the transition, and the transition temperature is thus modified to 96OC. Variations in a sample’s response under adiabatic conditions are observed and possible reasons are discussed. Testing in adiabatic mode provides new insights into the sulphide self-heating process that complement the test designed to identify propensity to self-heat. Keywords: Self-heating; Stage A/Stage B; transition; rhombic/monoclinic elemental sulphur; adiabatic heating

Jan 1, 2020

By SUHAINA ISMAIL, NORLIA BAHARUN, SHAIK ABDUL RAHMAN, WAN NUR SYAFIQAH ANUAR, MOHAMMAD REZAEI ARDANI

Hypochlorite leaching system is a strong oxidizing solution for metal sulfides, which are naturally associated with gold extraction. This study evaluated the hypochlorite leaching of refractory gold ore by using the response surface method–central composite design (RSM-CCD) as a statistical approach in determining the optimum condition of gold extraction from refractory gold ore. The studied parameters for the gold recovery were pH (4 to 6), concentrations of Ca(OCl)2 (0.5 to 1.5 M) and NaCl (2.5 to 3.5 M) in the solution. It was found that the maximum gold extraction of 82.46% (13.85 g/t) was achieved at a pH of 4.0 with NaCl and Ca(OCl)2 concentrations of 2.93 M and 1.08 M, respectively. The statistical analysis also revealed that the amount of gold recovery in chloride solution was significantly depended on pH as the main factor, followed by concentrations of Ca(OCl)2 and NaCl.

Jan 8, 2021

By William Hissem

The topics in the title line of this article are desirable and applicable to entire industries that exist outside the realm of the ISEE’s readership. But the issues I will discuss herein are specific to those who drill, blast, and excavate rock as part of their business. Civil and site construction projects, mines, and quarries specifically comprise the group who will benefit from this discussion.

Jan 1, 2014

By S. Tshikhudo

This paper outlines an investigation into the recovery of saleable fractions of coal from ?as-arising? South Export Plant effluent streams, using Baleen microscreening technology. South Export Plant, a subdivision of BHP Billiton Energy Coal SA (BECSA) Coal Processing, is a two-module plant treating 2000 t/h. The nominally -150 µm coal is untreated and is therefore passed from classifying cyclones to the thickeners for process water recovery. The thickened underflow is pumped into a series of slurry cells for further settling and recovery of supernatant water. The marginal quality, moisture content, and handlebility of this settled material renders it unsuitable for inclusion into saleable products and it is thus stockpiled and trucked to designated pits for disposal. Over the years, stockpiling and trucking has become an overly expensive exercise. In an effort to recover some of this cost, a task team was assigned to investigate less costly options to process slurry across BECSA plants. Various technologies such as froth flotation, sieve bends, and Reflux Classifier were considered, although the results were generally not beneficial ? this could be attributed to weathered/oxidized coal. A decision was made to pursue an alternative approach by testing the suitability of the new ?Baleen Filter?. The concept is to screen out the higher-grade fraction (+50 µm) as saleable product and reject the finer fractions to the slurry ponds. The Baleen Filter was found to effectively screen at an acceptable efficiency between 94% and 99.99%, with a very sharp cut-point (d50 and Ep). The actual yields from the screening results were better than the predicted yields in terms of both mass and energy as predicted from feedstock analysis.

Jan 1, 2014

By A. A. Hejja

The effect of composition on electrical conductivity, viscosity and liquidus temperature of the slags was investigated in the temperature range of 1300" to 1450°C. The synthetic slags containing CaO, MgO, SiO,, A1,0, and FeO were similar to those employed in the electric furnace smelting of sulphide Cu-Ni concentrates containing PGM (Platinum Group Metals) from the Merensky Reef of South Africa. FeO and SiO, were found to affect the viscosity and conductivity the most while liquidus temperature depended on MgO content in addition to these. The activation energy for electrical conduction was found to vary from 67 to 159 kJ/mol and that for viscosity from 125 to 209 kJ/mol. Optimization of the slag composition was attempted on the basis of opposite trend of the viscosity-electrical conductivity relationship with slag composition.

Jan 1, 1994

By P. M. Pettit

Hydrologic investigations at Gold Quarry began in 1989 and continued through 1991. Hydro-stratigraphic units include Tertiary sedimentary rocks, Paleozoic siltstones and carbonates. These units display complex and variable aquifer parameters as a function of faulting and hydrothermal alteration, creating compartmentalized hydrologic domains. Testing has included step-tests, spinner production logs and constant discharge tests. Two Three-Dimensional Finite Element Models have been developed, one for optimizing the pit dewatering system and the second for predicting regional impacts of dewatering. Aquifer testing and long term pumping have been used to calibrate both Finite Element Models.

Jan 1, 1992

By James K. Gowans

The Red Dog Operation is located in northwestern Alaska at Latitude 68°, 100 miles north of the Arctic Circle and 50 miles inland from the Chukchi Sea. The orebody was acquired by the NANA Regional Corporation, (an Alaska Native Corporation established by the Alaska Native Claims Settlement Act of 1971), in 1980 in their land selection. In 1982 Cominco American and the NANA Corporation signed a development agreement and Cominco Alaska Inc., a wholly owned subsidiary of Cominco American, was formed to manage the Red Dog Project. An extensive exploration program in 1980 -1982 outlined a mineral inventory of 85 million tons, at a grade of 5.2% Pb, 17.1 % Zn, and 2.4 oz/ton Ag, which makes the Red Dog the second largest deposit ever discovered. Broken Hill, in Australia, is the only zinc orebody which was originally larger than Red Dog. The design of the facilities is to process 2.1 million tons of ore annually, which will produce 560,000 tons of zinc concentrate, 100,000 tons of lead concentrate and 50,000 tons of bulk lead/zinc concentrate.

Jan 1, 1991

By Robert McClure, Carlton Lehman

Rendering safe explosives in an urban environment presents a unique challenge due to the safety concerns and disruption to the general public. Potential damage to the surrounding homes, businesses, utilities and transportation infrastructure are some of the major concerns when planning the render-safe operation. Engineering controls to mitigate blast effects, such as damaging air over pressure levels, material ejection and ground borne vibration, need to be implemented as part of the operation. Monitoring of seismic and air overpressure during these operations are needed to protect against potential claims when controlled or unplanned detonations occur. Two recent render-safe operations conducted in and around urban environments dealt with deteriorated, sensitive dynamite and damaged blasting caps. Utilizing innovative neutralization chemicals and processes to render-safe the deteriorated dynamite, while protecting the general public, proved to be the safest, most environmentally responsible and cost-effective way to approach the problem. In both cases, the explosives, old dynamite and detonators were found in abandoned, unlocked magazines. The dynamite was in a significantly deteriorated state, which was evident due to the nitroglycerine found leaking in,around and under the dynamite cartridges. Iron wire permissible electric blasting caps were also found in a corroded condition with exposed explosives and un-shunted lead wires. With occupied buildings within 180 feet (54.86 meters) of the magazines, any procedure (e.g. transporting, countercharging, burning) that could potentially cause a detonation was not an option. In the event of an unplanned detonation during neutralization operations, several blast mitigation methods were employed to safeguard the site. This operation and a similar one with over 1,000 pounds of crushed and buried leaky dynamite were unique since all the explosives were rendered-safe and neutralized on site. The use of advanced neutralization products and filtering processes allowed for a safer, more environmentally responsible way to resolve the problem. The magazines and all residual solids and fluids were tested and confirmed by independent labs to have no explosives residues. The effluents were treated on site, tested and met safe levels, so they were disposed of at a local municipal wastewater facility.

By D Caffrey

To demonstrate the advantages of using electronic delay detonators over pyrotechnic detonators, a trial using the DNES Dynatronic System was conducted at the KCGM Mount Charlotte operation in 1998. The trial clearly demonstrated that accurate control over the firing delay time between blastholes can lead to fragmentation improvement and ground vibration energy control which are two important issues for the Mt Charlotte underground operation. Excellent fragmentation was achieved by employing a 12 ms delay sequence. Detailed fragmentation analysis has shown a 10 to 20 per cent passing increase for the rock fragment size from 0.1 to 0.4 m compared with the pyrotechnic detonator firing. There was no increase in ground vibration level on the surface with the electronic detonator firing even though the electronic detonator firing had a much shorter blast duration than the pyrotechnic detonator firing. In fact, our energy calculation has clearly shown that much less energy had been propagated to the surface from the blast using electronic detonator firing.

Jan 1, 1999

By V. F. Kozyrev, L. B. Tsymbulov, L. Sh. Tsemekhman, A. N. Golov

Gipronickel Institute, JS has developed a new process and equipment for melting copper raw material in a two-zone Vaniukov furnace resulting in the production of white matte and low-grade slag in terms of copper content. Tests on processing copper nickelcontaining ore from Norilsk (Cu - 17 %), Ni - 3 %) were conducted in Vaniukov pilot furnace (total area 11.4m2) of Severonickel Combine. The amount of the processed material was about 11 thousand tons. Principal results of pilot testing are presented.

Jan 1, 2007

By Francis X. Cannaday

The Bureau of Mines developed equipment to measure the sonic velocity of pulses transmitted through rock samples varying in size from laboratory specimens to mine pillars in place. Pulses are produced by electronically excited piezoelectric ceramic transducers. Special equipment components were developed by Bureau facilities; other components are commercially available. The technique permits a nondestructive, repetitive, stable, shaped pulse to be used in place of explosive caps or hammer blows. Longitudinal wave travel time measurements were taken on an oscilloscope screen; transverse wave measurements were taken under special field conditions. Results were consistently repeatable within the accuracy of the oscilloscopes utilized.

Jan 1, 1966

By W. E. Howlett, R. L. Slobod

Jan 1, 1965

By Liyuan Chai

The corrosion mechanism of A3 steel induced by chloride ions in the purified water had been investigated with the A C Impedance technique. The results showed that there were another two factors which determined its electrochemical corrosive rate: the electrode potential and coverage ratio of chloride ions on the surface of A3 Steel. The corrosion mechanism of A3 steel in the solution with chloride ions emendation was two steps of electrode process with the rate-determining step of 0,32kFeClFeCle+--¾¾®++.

Jan 1, 2009

By T. Shi, Q. Yuan, S. P. Vanka, B. G. Thomas

"The quality of continuous cast steel is greatly affected by fluid flow in the mold region, especially involving transient phenomena. Mathematical models are being applied to investigate many different aspects of these phenomena, but their accuracy must be validated before they can be applied with confidence. As part of a long-term effort to develop and apply comprehensive models of the continuous casting process, this work evaluates the relative accuracy of models of three different fluid flow phenomena in continuous casting through comparison with measurements.Firstly, transient flow simulations of velocities in the mold region are compared with digital particle image velocimetry (PIV) measurements in a single phase water model. Large-eddy simulations (LES) are found to reasonably match the flow measurements, including transient flow variations, except at long time scales, which could not be modeled owing to the excessive computation costs. The standard K-e model produced very good agreement with time-averaged velocities for relatively little computation time, although it is inaccurate at predicting the transient variations. Secondly, particle trajectory calculations are compared with water model measurements to study the distribution and flotation removal of inclusion particles. The LES model was able to match the measurements both qualitatively and quantitatively. Thirdly, steady, multi phase flow computations are compared with flow patterns observed in both a water model and an operating steel caster with argon gas injection. For the same conditions, the water model and steel caster produced very different flow behavior. The computational model was able to match the measured flow patterns in both cases.This work suggests that computational flow modeling has the potential to match real processes as well or better than water models, especially when complex related phenomena such as particle motion and multiphase flow are involved. Much work is still needed to further improve the models and to apply them in parametric studies."

Jan 1, 2001

By C. Takano

The integrated iron and steelmaking industry generates large amounts and many types of solid dusts and sludge, at different phases of the production. Within these are: sludge of the Blast Furnace; coke fines; fine and coarse fractions from oxygen converters; sludge from water treatment at rolling mill unit; and others. In this paper the above dusts and sludge were physically and chemically characterized. The obtained results allowed defining self-reducing pellets using these materials. The high temperature behavior of the pellets were evaluated. Good results, with no decrepitation and swelling, and high yield of reduction, show that it is feasible to recycle them, as self-reducing pellets, in oxygen steelmaking converter.

Jan 1, 2001

By T. M. Yegulalp

A short review of the current practice and recent developments is followed by a description of a newly developed approach for the solution of the optimum ultimate pit limit problem. The new approach utilizes the network modeling of the problem for solution by maximum flow algorithm. The latest developments in the implementation of maximum flow algorithm present significant time and memory savings as compared to initial development due to Ford and Fulkerson. Results of a series of computational tests are presented to demonstrate how this approach performs as compared to the well-known Lerchs Grossman algorithm. It is also shown that the solution by the new method will automatically include several optimal solutions based on predetermined number of benches to be included in the analysis.

Jan 1, 1993

By Brendan Demich, Linda L. Chasko, Brendan Macdonald, Timothy J. Orr, Jessie J. Mechling, Cassandra Hoebbel, Jason Navoyski, William Helfrich, Jessica Cohen, Paul E. Schmidt, Jennica L. Bellanca

The National Institute for Occupational Safety and Health (NIOSH) in partnership with the Mine Safety and Health Administration (MSHA) developed VR Mine Rescue Training (VR-MRT). It is a training platform that allows mine rescue team members to explore virtual emergency scenarios collaboratively. Team members use a head-mounted display to visualize and interact together with equipment, hazards, and dynamic ventilation. All player actions are recorded and displayed for debriefing. Researchers at NIOSH demonstrated the training platform at various mine rescue competitions, including the International Mine Rescue Competition, and collected feedback. Participants’ responses were overwhelmingly positive. This paper describes the development of the software platform and the results of the usability surveys and interviews.

Jun 25, 2023