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By K. Ihara, R. Akiyoshi, Y. Takaki, S. Kang, H. Shishido

"Tensile tests and scanning electron microscopy-electron backscattered diffraction (SEM-EBSD) analysis were performed in an Al-Mg-Si alloy to clarify the effect of annealing and cold-rolling reduction on the texture formation. The hot-rolled specimens were cold-rolled with the reduction of 58-75%(CR1), followed by annealing at 773 K for 5 min(IA). The secondary cold-rolling(CR2)for the IA specimens with the reduction of 33–66%, followed by the solution heat treatment(ST), were performed. Focusing on the CR1 and CR2 specimens, the average r-values increased with higher primary and lower secondary cold-rolling reduction, respectively. This was considered to be due to the increase of r-values measured in the direction of 45 degree with respect to rolling direction, caused by the formation of the ß-fiber components (Brass {011}<211>, Copper {112}<111> and S {123}<634>) with high density. Based on the texture analysis of annealed specimens it was suggested that the high density of the ß-fiber components after IA and the small amount of stored strain energy of CR2 introduced by the lower cold-rolling reduction remained the ?-fiber components even after solution treatment.INTRODUCTION Al-Mg-Si alloys have been applied to automobile body applications, due to their excellent paint-bake hardening (age-hardening) and corrosion resistance compared to other aluminum alloy. On the other hand, the mechanical properties and deep drawability of Al-Mg-Si alloys are inferior to those of steels. Thus, it is important to improve the mechanical properties and deep drawability in order to expand the application components. One of the best methods to improve the deep drawability is to increase the Lankford coefficient (r-value). Previous studies reported that the increase of the average r-value ( ) improves the deep drawability. The relationship between the r-value and texture of the alloy is also well known. Inoue et al. reported that the ß-fiber components, such as Brass ({011}<211>), Copper ({112}<111>) and S ({123}<634>), increase the r-value measured in the direction of 45o with respect to the rolling direction. r"

Jan 1, 2018

By J. Bardinas

"The use of autogenous mills has become widespread, owing to their capacity and favorable capital and operating costs. Optimal operation of these systems is critical, given their high energy consumption and effect on downstream processing. A considerable effort has been spent over the years in the development of advanced control systems to achieve a better performance in this regard. However, despite significant advances, the problem still remains challenging, owing to the nonlinear behaviour of the system with respect to the mill variables, and, the unmeasured ore variability come from the mine.The mill load, in particular, can be seen as a state variable of the mill, which could be important for; modelling and control, and, important insights into the mill behaviour. In this investigation, time series cluster analysis was performed using online mill load measurements in order to identify the different control states of the mill. More specifically, this time series was divided into short non-overlapping segments. A distance matrix was set up for each segment and the information was captured by means of textural features, similar to that used in multivariate image analysis. These wavelet and grey level cooccurrence matrix features could subsequently be used to rapidly identify the normal operating conditions from the feed disturbances in the mill.In principle, the methods and models presented here, once suitably validated and calibrated, could be used in online process monitoring of autogenous mills. They also could serve as a foundation for developing more advanced process control models."

Jan 1, 2016

By Z. Manafi

Bioleaching of a copper sulfide ore containing "activated pyrite", using a mixed culture of mesophilic bacteria, was studied. This type of copper ore had been found unsuitable for flotation because it produces a concentrate containing relatively high iron concentrations and, therefore, a low copper grade. Microscopic observations showed that pyrite particles had been activated by the formation of a thin film of chalcocite. Hence, a bioleaching process was considered as an alternative to treat this ore. Following shake flask and acid consumption tests, column tests of the crushed ore (75% -12.5 mm) were initiated and the effects of culture medium, agglomeration, and irrigation type on copper recovery were studied. The results showed that all the columns containing bacteria had copper recoveries around 90% compared to the abiotic control column with a recovery of 50%. It was concluded that bioleaching could be successfully utilized to process copper ores containing activated pyrite.

Jan 1, 2007

By Shin-Kun Ryi

The world nowadays faces many challenges associated with excessive utilization of fossil, fuels, such as poor air quality and greenhouse gas emissions. Hydrogen appears to be an attractive alternative to the conventional, fossil, fuels with better energy efficiency and less environmental, impact. Pd and Pd-based alloy are the most often used membranes for hydrogen separation due to their superiority over other membranes. However, the stability of the commonly-used thin Pd-based composite membranes at high temperatures still, remains a big challenge. In this presentation, we will, report our progress on thin Pd-Ru alloy composite membrane by electroless plating high temperature applications.

Jan 1, 2010

By J. A. Finch, A. M. Elmahdy

Blending frothers is becoming common in flotation practice apparently enhancing performance. However, there have been no studies to understand the blend mechanism. In this paper, the effect of two frother blends ofF150 (polyglycol) with MIBC or pentanol (both alcohols) on bubble size, gas holdup and froth height is reported. The blends focused on a small addition of the polyglycol to the alcohols as base frother. The tests showed that the bubble size at blend concentration below the critical coalescence concentration (CCC) of the base frother was decreased but was significantly larger above the base CCC. Froth build-up showed a strong synergistic effect.

Jan 1, 2009

By C. A. Pickles, K. Mackowiak

Black Thor chromite ore from the Ring of Fire deposit in Northern Ontario was carbothermically reduced in a microwave system to produce a ferrochromium alloy. The as-received ore contained 43.0% Cr2O3, 19.9% Fe2O3, 14.5% MgO, 13.4% Al2O3, and 7.0% SiO2. Activated charcoal was utilized as the reducing agent. Firstly, TGA/DTA and permittivity studies were carried out in order to determine the relationship between the reduction process and the microwave susceptibility. Secondly, microwave reduction experiments were performed on the chromite ore. The variables investigated were; the amount of carbon, processing time, input power and type of atmosphere. A maximum chromium grade of 76.1% and a chromium metallization of 82.7% were obtained for a processing time of 20 minutes, a power input of 800 W, and a carbon addition of 15% in an argon atmosphere.

Jan 1, 2017

By J. H. . MORGAN

Talc-soapstone deposits exist in Patton Township of Quebec and have been mined by Bakertalc Inc. or its predecessors since 1938. The company produces products ranging from purified and micronized talc through to soapstone lumps. The deposits are found within serpentinite dykes and are zoned. Zoning grades from a serpentine core through zones of talcmagnesite, schistose talc and talc-chlorite schist be/ ore reaching the wall rock of quartz-sericite-chlorite schist. Talcmagnesite zones generally comprise 80 to 90% of the mined rock. The serpentinite dykes containing the talc probably were originally post-Ordovician peridotite of the same series that hosts the Eastern Townships asbestos deposits. Alteration of serpentine to talc-soapstone and magnesite apparently resulted through addition of silica and carbon dioxide along shears and fractures. Talc concentrations occur also at the intrusive contact between dykes and wall rock. The present Bakertalc Inc. operation at the Van Reel Mine is being worked from an inclined shaft 200 m below surface. The talc rock undergoes a variety of milling processes, depending on its particular market, be/ ore being bagged and shipped.

Jan 1, 1984

By S. Jordanov

The nature of processes that take place on top of copper bearing grains during the suppression of copper acid drainage from mine tailings was studied on a grain model. Cyclic voltammetry (C.V.) was employed as an experimental technique suitable for indirect measuring of copper leaching. Experiments were done in sulfuric acid (pH=2) at electrodes that progressively approach the real situation during acid main drainage, starting with Cu-metal, then with CuO and finally with CuO covered with CaSO4. Oxidation was found to be the only process that takes place on metallic copper electrode anodically polarized up to 2 V vs. Cu/CuSO4 reference electrode. Dissolution is intensive and reaches up to 50 mA.cm-2. When the same was repeated, but on CuO electrode, anodic currents were some 4 times lower than on the bare metallic surface. This indicates that the electrode material is not completely oxidized to copper(II)oxide and the Cu(O) or Cu(I) residues are oxidized during the anodic polarization. This explains the diminished dissolution. Dissolution is further restricted at electrodes covered with CaSO4. It is some 20 times lower than on the bare oxide electrode. When the second layer of CaSO4 was applied, anodic currents were another 15 times lower. Total decrease of anodic currents when transition is made from Cu-metal to CuO covered with 2 layers of CaSO4 reaches up to 7.500 times. C.V. measurements produced a proof that mechanical blockage is the way how lime prevents leaching of copper bearing grains in immobilization experiments referred elsewhere.

Jan 1, 2007

By Guadalupe Sanchez, Roel Cruz, Sergio Castro, Claudia Beltrán, Isabel Lázaro

The recovery of zinc in refineries is strongly affected by the formation of zinc ferrites during the roasting of zinc concentrates. To achieve the highest zinc recovery most of these plants operate under high acidity and high temperature conditions in their leaching circuits. However, under these conditions high iron dissolution occurs. For iron control the common practice is to precipitate it as jarosite, and calcine is normally used as neutralizing agent. This practice causes a significant loss of metal values associated with the calcine, such as zinc ferrites and silver insoluble phases. These metal values are carried by the jarosite into confined waste in many plants. In order to diminish such losses, it is necessary to use a neutralizing agent that could substitute the use of calcine. An alternative neutralizing could be the basic zinc sulfate (BZnS). This work presents the results of a laboratory analysis on the required conditions for the BZnS production from process streams of a zinc refinery plant. Neutralizing behavior of BZnS was evaluated in iron precipitation as jarosite, in order to establish the feasibility of replacing the calcine and decrease the loss of zinc and other metals values during the iron removing step of the hydrometallurgical circuit of the zinc refinery under study.

Jan 1, 2014

By C. T. Wiliams, John B. Bush, John Lamb

"THE TOWN OF HEDLEY is in the valley of the Similkameen River, about 200 miles east of Vancouver and 25 miles north of the International Boundary between British Columbia and the State of Washington. The main ore deposits are located on Nickel Plate Mountain, northeast of the town.The outcrop of the Nickel Plate system of orebodies is at an elevation of 5,900 feet. It was discovered in 1898 by prospectors and sold in the following year to the Marcus Daly interests of Butte, Montana. Production commenced in 1904 under the name of Daly Reduction Company. In 1909 control passed into the hands of the Hedley Gold Mining Company. Operation of the mine continued until 1930, when exhaustion of known ore reserves forced it to close. Upon the recommendation of Paul Billingsley (3) the mine was optioned by the 1. W. Mercer Exploration Company in 1932. Production began once more in 1934 under the name of Kelowna Exploration Company Limited, and was practically continuous until August 1955, when the mine was again shut down. The name of the latter company was changed in 1951 to Kelowna Mines Hedley Limited.The Mascot Fraction, a small wedge-shaped claim lying astride the Nickel Plate orebodies, was mined by Hedley Mascot Gold Mines Limited between 1935 and 1949. The geological setting and structural control of ore are essentially the same as in the adjoining Nickel Plate Mine.Total production from all operations on Nickel Plate Mountain to the end of 1954 was approximately 3,800,000 tons of gold ore, with a gross value in excess of $48,000,000.General GeologyNickel Plate Mountain occupies the gentle westerly dipping limb of an asymmetrical anticline, the axis of which trends northeasterly. The rocks are composed of a thick pile of Triassic limestone, limy argillite, and quartzite, -resting on a flattish floor of granodiorite near the base of the mountain. Associated with these sediments is a host of porphyritic sills and dykes of gabbro-diorite composition. In the mine area east-west brown soda-rhyolite dykes and north-south black andesite dykes crosscut all the other formations and the ore, probably following steep later fractures."

Jan 1, 1949

By J. Ellis Thomson

For many years the value of qualitative microscopic investigation has been recognized in both of the fields of pure and applied science. In particular, its aid has been invoked in the determination of rock specimens in thin section, and some at least of the interrelations of minerals present in any one section have been observed and, to a limited extent, applied for the solution of different problems. During the past decade this form of research has also been diverted to the determination of ore minerals in polished section, with some observation of their structural relations. Microscopic research of a quantitative character, on the other hand, while started nearly one hundred years ago, has found but a limited application in petrography and has scarcely been used at all in the more modern science of mineragraphy. This is very largely due to the methods employed, since most of them consumed too much time and were, in addition, too laborious to encourage many workers in their use. The details of procedure for these earlier methods will be found in another paper by the writer, and will be omitted from this discussion as being of small interest to practical mining men.

Jan 1, 1930

By M. J. Baker

Energy and Minerals Australia Ltd are undertaking a study of the recovery of uranium from the Mulga Rock Deposits in Western Australia. Approximately 80-90% of uranium identified to date is present as tabular layer up to 5 m thick within a lignite seam 30 m to 50 m below surface. Other metals are also present. Metallurgical studies at ANSTO Minerals laboratories in Sydney have focused on identifying a suitable uranium leaching process and assessing the possible downstream impacts of the organic material in the ore. The extraction of other metals has also been examined. This paper provides the results of testwork performed at ANSTO to date.

Aug 1, 2010

The dissolution of chalcopyrite has received a significant amount of attention. The predominant paradigm of investigation is that its rate of dissolution is limited or passivated by a surface coating or film of material. The common candidates for such a passivating coating are numerous: polysulfide coating, metal deficient layers, copper sulfide coating, bornite layers, jarosite precipitates, and elemental sulfur films. While this line of explanation, that is, the explanation based on passivation, seems to have won some form of consensus with researchers, there is another explanation for the results that can account for all the results observed. Crundwell (1988) proposed that the solid state properties of chalcopyrite, in particular, the semiconducting properties, are responsible for the observed behaviour of chalcopyrite. The purpose of this paper is to outline the semiconductor mechanism of dissolution, and to show how this mechanism accounts for all the observed phenomena recently reported in the literature. The paper outlines the semiconductor mechanism of dissolution, shows how this mechanism accounts for the dissolution

Jan 1, 2014

By Adrianus (Adrian) Halim, Tomas Bolsöy, Stina Klemo

"This paper describes the ventilation system used in underground hard rock mines in Sweden and Finland, which is very different than the system used in other major mining countries such as Australia, Canada, South Africa, and USA. The system utilizes auxiliary fans with Variable Speed Drive to distribute primary airflow to working levels instead of regulators that are commonly used in other countries. Descriptions about Ventilation on Demand in this system and ventilation regulations in Sweden and Finland are presented in this paper. This paper also quantifies a comparison between the Nordic and the system used in other countries. KEYWORDS Auxiliary fan, Regulation, Ventilation on demand (VOD), Variable speed drive (VSD) INTRODUCTION The primary objective of an underground mine ventilation system is to provide sufficient airflow to dilute atmospheric contaminants that are produced by mining activities. Typically, a mine ventilation system consists of one to four primary fans, regulators to control primary airflow distribution to levels or panels, and auxiliary fans that distribute airflow to dead-end workings via ducts. Depending on circuit geometry, underground booster fans are sometimes used. This system is widely employed in many countries such as Australia, Canada, USA, United Kingdom, and South Africa. However, mines in Nordic countries such as in Sweden and Finland employ a different system, in which auxiliary fans instead of regulators are used to control primary airflow distribution, as well as distributing airflow to dead-end workings. This paper describes the general layout of Nordic ventilation system, its VOD and heating system, its comparison with the system that is widely used in other countries which is referred as “Non-Nordic ventilation system” in this paper, and the current ventilation regulations in Sweden and Finland. The comparison was quantified by doing simulations using Ventsim Design 5 software. DESCRIPTION OF NORDIC VENTILATION SYSTEM General System Layout Figure 1 shows a schematic of typical ventilation system used in Swedish and Finnish mines. The schematic was drawn by Franzen, Myran, Larsson, and Rustan from Stiftelsen bergteknik forskning (Swedish Rock Engineering Research Foundation) and the English translation is written next to the Swedish terminologies. The system is generally a push-pull system. None of Swedish and Finnish mines use exhaust system. As shown in Figure 1, the primary airflow is distributed to levels by auxiliary fans that are bolted to a bulkhead located in the access to intake raise/shaft. These intake fans are attached to ventilation ducts that distribute airflow to all working faces. The exhaust auxiliary fans, which are not attached to any ducts and also are bolted to a bulkhead located in the access to exhaust raise/shaft, then flow the exhaust airflow into the exhaust shaft. A small quantity of this exhaust air is directed into the ramp, which acts as another main exhaust airway. The deepest level is also equipped with booster fan(s) that draw air from the intake shaft/raise and direct it into the ramp to provide fresh air in the ramp. There is no free split in this system. Figure 2 shows a schematic of a level ventilation layout in the Nordic system. Figure 3 shows a photo of these auxiliary fans."

Jan 1, 2019

By R. L. Christie

"THE ISLANDS lying north of the Canadian mainland, and the large Boothia and Melville peninsulas, form one of the great archipelagos of the world; this sparsely vegetated and nearly unpeopled region extends about 1,500 miles east to west and 1,200 miles from the mainland to the northern tip of the northern-most island. Sea access to most of the islands is restricted by ice to the summer season, and the 'polar pack' ice of the Arctic Ocean presses the year round against the northwest margin of the archipelago. Although the region is remote, the accessibility has greatly increased through a network of weather stations, airfields and air routes connecting with southern centres.The area considered in this paper is that part of the island region underlain mainly by sedimentary rocks. In broad terms, this includes the land and sea areas of the archipelago and the adjacent continental shelf, but excludes the dominantly 'Shield' terrain of Baffin Island, and of Melville and Boothia peninsulas. An impression of the size and potential of this sedimentary region may be gained by comparing some areas: the land area of islands underlain mainly by sedimentary rocks is over 300,000 square miles or about 50,000 square miles greater than the area of Alberta. The total area of the region, including the continental shelf and the inter-island areas, may be double this figure, and may approximate one-seventh of the land area of Canada."

Jan 1, 1970

By P. G. West-Sells

At Barrick&apos;s Zaldivar Copper Mine in Chile, the addition of sulfuric acid to the ore going to heap leaching is a major expense. A process in which a portion of this acid is replaced by elemental sulfur added to the heap has been developed by Barrick and Westcoast Biotech that has the potential for significant cost savings. Initial shake flask tests with plant raffinate solution indicated that oxidation of elemental sulfur by a culture of sulfur-oxidizing bacteria, some indigenous to the Zaldivar heap, showed a significant lag period. This lag period could be reduced by dilution of the raffinate, but dilution would not be economical to implement at Zaldivar. Short (0.75 m) column tests indicated that after the initial lag period, sulfur biooxidation occurred steadily and the acid requirement for obtaining the same copper recovery as the control without sulfur was reduced by as much as 13 kg/t. These tests were followed by taller (5.1 m) column tests that confirmed the reduction in acid consumption, with no negative effect on copper extraction.

Jan 1, 2007

By C. Feng, D. W. M. Arrigan

Arsenic is often associated with gold mining operations and poses a significant health and environmental hazard. While a number of technologies are available for removing arsenic, none of them is effective under all conditions. Although adsorption is a promising approach, most methods focus on the purification of water under neutral or acidic conditions and tend to be less effective in gold mining process waters, operating under alkaline conditions. In this study, the removal of As (III) and As (V) from both arsenic-only solutions and simulated process waters using composite magnetic nanoparticles was investigated. The nanoparticles consisted of magnetite (Fe3O4) or maghemite (?-Fe2O3) cores covered by various metal oxides with Langmuir adsorption capacities of As (III) and As (V) ranging from 31.4 to 79.1 mg/g and 10.2 to 25.5 mg/g, respectively, in arsenic-only solutions at pH 9. Their adsorption capacities were further recognised by the adsorption tests conducted in simulated process waters. The ability to remove As (III) is of particular importance as it is harder to remove it from alkaline solutions. The magnetic cores allow simple and efficient magnetic recovery of the As-loaded nanoparticles.

Jan 1, 2017

By A. G. Pathan

Rock and soil mechanics investigations were carried out in block VIII at Thar Coalfield, Pakistan. Most of the strata were mainly composed of sand, with an average content of 67.68 %. Laboratory studies of rock and soil samples from drill hole GT-01 revealed that the strata in block VIII are very weak with an average uniaxial compressive strength of 3.59 MPa, an average tensile strength of 0.68 MPa, an average Young?s Modulus value of 0.234 GPa, an average cohesion of 129.19 KPa, and an average friction angle of 55.47°. Slope stability analysis, based on a probabilistic approach, was carried out using Slide-V software. Monte Carlo simulations have been applied to investigate the probability of failure in the slopes of an open pit lignite mine in block-VIII. From the slope stability investigation, it was found that the probability of failure is 0 % at a slope angle of 16°.

Aug 1, 2013

By Hajime Miki, Gde Pandhe Wisnu Suyantara, Shigeto Kuroiwa, Eri Takida, Tsuyoshi Hirajima, Masashi Yamane, Yuji Imaizumi, Mitsuru Sawada, Keiko Sasaki

Selective flotation of molybdenite and chalcopyrite using various oxidation treatments (i.e., ozone treatment, hydrogen peroxide, and Fenton-like reagent) was studied in this work. It was found that ozone treatment produced a depressing effect on both minerals, resulting in a lower separation of both minerals. On the other hand, oxidation treatment using hydrogen peroxide (H2O2) and Fenton-like reagent could deliver selective oxidation on chalcopyrite surface and depress its floatability. However, bench-scale copper- molybdenum (Cu-Mo) flotation tests show that oxidation treatment using H2O2 required a higher dosage of H2O2 and a longer treatment time in order to deliver comparable flotation results to that of conventional Cu- Mo flotation using NaHS treatment. On the contrary, Fenton-like reagent could deliver selective Cu-Mo flotation results comparable to that of NaHS treatment at a lower dosage of H2O2 and a shorter conditioning time. Contact angle measurements and X-ray photoelectron spectroscopy (XPS) analysis were employed to understand the depressing mechanism of these oxidation treatments. It was found that the chalcopyrite surface covered by various oxidation products that render the surface hydrophilic. Meanwhile, the surface of molybdenite was slightly oxidized, making the surface remained hydrophobic. INTRODUCTION Molybdenite (MoS2), the main source of molybdenum, is associated with copper sulfide minerals, mainly chalcopyrite (CuFeS2), as a trace mineral. Molybdenite is a valuable mineral and plays an important role in making the copper-molybdenum (Cu-Mo) processing plant economically viable (Laskowski, Castro, & Ramos, 2013). Therefore, it is important to recover molybdenite efficiently and effectively and separate it from copper minerals. Conventional separation of copper and molybdenum minerals is usually carried out in selective Cu- Mo flotation process using a copper depressant (i.e., sodium hydrosulfide (NaHS), Noke’s reagent, or cyanides) (Ansari & Pawlik, 2007; Bulatovic, 2007). However, this process still suffers due to imperfect molybdenum recovery. Moreover, the copper depressants use in this process are toxic and harmful to the environment. As alternative, various methods have been developed to replace these toxic and hazardous depressants, for example, by synthesizing new non-toxic or low-toxic depressants or by using various oxidation methods such as sodium hypochlorite in an alkaline medium, manganese dioxide, oxygen, and plasma pre-treatment (United States Patent Office Patent No. US 2559104 A, 1951; Patent No. US2238250 A, 1941; Barzyk, Malysa, & Pomianowski, 1981; Hirajima et al., 2014). However, the oxidation phenomenon and mechanisms are still not clear since detailed surface analyses have not done and the plasma pre-treatment method is facing technical issues for industrial scale application.

Jan 1, 2019

By Jeonghwan Kim

Intelligent Excavation System (IES) has been considered to be one of the desirable solutions to improve the productivity, quality and safety of the current earthwork processes. IES is composed of various hardware and software modules including task planner (work command generator), local and global work environment sensors, GPS and other sensors to acquire the excavator?s status, robotic controller and electronic valves, and the manipulator (excavator). A data communication manager was required to coordinate the signal or data-flow in between these modules considering the operational status of IES such as; excavation start/completion, truck detection, terrain model update, emergency stop, local sensing, GPS/motion sensor data handling, and so on. This paper presents the role and functions of this data communication manager. After every possible operational status of IES operation was identified, a protocol of each communication process in the form of string-type was made. The components of IES are connected with either wired or wireless network. Therefore, they can communicate with the manager using socket (TCP/IP) communication. The data communication manager is also capable of accessing a web-based project management information system, which constantly updates the performance of excavation robot to online database.

Aug 1, 2013