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By J. Groppo, W. Zhang, R. Honaker

"The flotation of monazite is depressed when using hydroxamic acid as a collector in the presence of calcium ions which may exist due to the dissolution of minerals such as calcite. Minor dosages of sodium hexametaphosphate (SHMP) were found to effectively depress calcite, whereas the flotation of monazite was not impaired in single mineral flotation tests. However, in a mixed mineral flotation system, monazite flotation was depressed significantly. The mechanism of hydroxamate adsorption on monazite and calcite, the depression mechanism of calcite on monazite, as well as the depression mechanism of SHMP on calcite and monazite were studied using micro-flotation, electro-kinetic, and adsorption tests. Findings indicate that the adsorption of hydroxamate on monazite was due to chemisorption while adsorption on calcite was a result of physical interaction. SHMP significantly increased the negative charges of calcite surfaces which depressed the adsorption of the hydroxamate anions on the calcite surfaces due to an elevated electrostatic repulsion force. When calcium-rich minerals such as calcite are mixed with monazite, the calcium ions dissolved from the mineral surfaces specifically adsorb onto the phosphate oxygen sites on the monazite mineral surfaces thereby causing depressing effects. The addition of SHMP to suppress collector adsorption on the calcite surfaces interacts with the calcium species that were specifically adsorbed onto the monazite surface, which prevents hydroxamic acid adsorption onto the rare earth oxygen sites due steric hindrance and results in the flotation depression of monazite. INTRODUCTIONAs one of the commercial rare earth ores, monazite has been widely exploited to produce additives for catalysts, batteries, alloys, etc. Because of the complexity and the fine nature of some monazite ores, methods such as gravity, magnetic, and electrostatic separation to treat beach sand monazite fail to produce satisfactory concentrates, suggesting the use of floatation is warranted (Cheng, Holtham, & Tran, 1993). The primary associated minerals of monazite ores include ilmenite, quartz, zircon, rutile, sillimanite (Dixit & Biswas, 1969; Pavez a& Peres, 1994, 1993). Using sodium oleate as collector for monazite has been reported in many studies (Cheng et al., 1993; Dixit & Biswas, 1969; Pavez & Peres, 1994, 1993). Several investigations have reported maximum floatability of monazite occurring at pH values between 8 and 9 (Cheng et al., 1993; Dixit & Biswas, 1969). A study conducted by Pavez and Peres (1994) compared the use of hydroxamate and sodium oleate for the treatment of a monazite ore and found that hydroxamate significantly improved the grade of rougher concentrate."

Jan 1, 2016

By Liangtian Liu, Tie Ou, Guangqiang Li, Chenghuan Yu

For stabilizing the production of containing nitrogen steels, a study on nitrogen absorption behavior of killed molten steel has been carried out by means of the RH vacuum device in which nitrogen was used as a driving gas. The results showed that there was an increase of nitrogen content in molten steel under vacuum processing but the rate of nitrogen absorption was slowed down by the surface active elements. Therefore, a kinetic equation for nitrogen absorption of molten steel with apparent first order reaction was derived by constructing a modified model in which the adsorption of closed surface site was taken into account. The experimental results confiimed that the calculated values agreed with the observed ones. This model is suitable for the prediction of nitrogen adsorption operation for containing nitrogen steels.

Jan 1, 2004

By F. Hassani, J. Peck, D. J. Lucifora

The performance of a rotary blasthole drill is heavily dependent on the material being drilled. This material is a microcosm of the in-situ geology that makes up the surface mine in which the rotary blasthole drill is deployed. The performance metrics that are influenced by the in-situ geology are penetration rate (distance drilled per unit time), rotary torque and to a lesser extent rotary speed and vibration. For simulation and testing purposes it is useful to have a validated plant model based upon the application of study. Once validated, a plant model can be used to perform simulation based testing as a supplement and possibly in place of more expensive and logistically complex field testing. Previous studies in the field of rock mechanics have supplied proven models that relate the performance of a rotary blasthole drill to the material being drilled for a given rock type with a given drill bit. In this study, field based experiments were conducted in an active surface mine on a working rotary blasthole drill and the corresponding monitoring while drilling (MWD) data was recorded. Data analysis was then performed on the collected field data. The techniques used successfully fit the collected MWD data to the previously proven rock mechanic models. This paper explores the theory relating rotary blasthole drill performance to the material being drilled, illustrates the required data collection and data analysis techniques, and demonstrates the ability of these techniques and the known rock mechanic models to provide a simulated plant model for the drilling process that can then be validated. This validation is also discussed.

Jan 1, 2015

By M. Sukhram

This paper presents a technique to determine the direction of velocity in liquid aluminum (Al) by measuring the temperature distribution within a cylindrical rod while it is inserted into the flow. The heating pattern of the rod is a result of the interaction of the thermal fields of the rod with the liquid Al. This interaction freezes aluminum onto the cylinder in a characteristic pattern and as a result the temperature response within the rod also follows a distinctive heating pattern. Monitoring the temperature within the cylindrical rod as a function of spatial and temporal coordinates, the direction of velocity can be inferred. Experimental research work involving liquid Al was conducted at the University of Toronto using the Revolving Liquid Metal Tank (RLMT). The RLMT is a resistance furnace which can hold up to 50kg of liquid Al. In this RLMT tangential velocities up to 0.35m1s can be generated. Experimental data for different superheat and magnitude of velocity demonstrate that the sensor records different heating patterns under different fluid flow conditions. Using the transient temperature information, the direction of velocity of the molten Al flow field can be detected.

Jan 1, 2011

By Huan-Qiang Zhang, Gang-Hai Huang, Yu-Yong Jiao, Fei Zheng, Zhang. Xiu-Li

An efficient and accurate three-dimensional (3-D) contact detection algorithm is of vital importance in large-scale computing of discontinuous deformation analysis. The contact detection algorithm takes up a large proportion of the whole calculation time because of the increasing calculation number in three-dimensional case. For block systems which consist of convex polyhedrons, the efficiency and accuracy of the contact detection algorithm is a great challenge. The presented contact detection algorithm in discontinuous deformation analysis (DDA) method is carried out in three phases: the global neighbour searching, the local contact type searching and the contact transferring. A contact detection algorithm for 3-D DDA is presented with some improvements on the three phases. A grid-based global neighbour searching algorithm is used to eliminate unnecessary neighbour blocks to the exact number. The local contact type searching includes two steps. In the first step, the common plane method is used to determine the contact type between convex polyhedrons. In the second step, the contact pairs detected by the common plane method are divided into four basic types. In the third phase, the four contact types are transferred into two basic contact types, vertex-to-face contact type and edge-to-edge contact type, which are managed in a uniform procedure. Three verification examples are calculated, the results show that the proposed algorithm based on the three contact detection phases is robust and efficient.

Jan 1, 2015

By Fathi Habashi, Ahmet Deniz Bas

"The mechanism of leaching of semiconducting minerals such as PbS, ZnS, UO2, etc., has been the subject of intensive speculation by hydrometallurgy researchers in the early 1950s who assumed the formation of intermediate surface complexes that could be neither separated nor identified by physicochemical techniques. The electrochemical theory of leaching introduced in the late 1960s resolved this problem by comparing the leaching process to a corrosion phenomenon similar to the corrosion of metals. Few years later, experimental evidence showed that anodic and cathodic zones are formed on the dissolving mineral although no electric current is imposed on the mineral during dissolution. A discussion of these findings is outlined.INTRODUCTIONIn the early 1950s researchers realized that kinetic studies for leaching ores are as important as thermodynamic calculations. It was also during this period that the concept of species adsorption on mineral surfaces has dominated the interpretation of the mechanisms of most reactions. This may have been due to the fact that many researchers of this period came from the mineral dressing sector and were influenced by flotation theories. However, when the knowledge of lattice defects and the semiconductivity of minerals became known and their importance in extractive metallurgy was realized, there was a need to explain the leaching reactions in light of these modern theories (Habashi, 1969, 1970). Semiconducting minerals of importance in metallurgy are two categories: the sulfides such as those of copper, lead, zinc, and the oxides such as those of uranium."

Jan 1, 2016

By Farzad Mohammadi, Patrick Littlejohn, David Sanguinetti

Arsenic levels in metal concentrates are increasing as mining companies turn to developing low grade and complex ores. When arsenic bearing minerals are smelted, arsenic deports as gases which must be neutralized by a scrubber system. The resulting scrubber effluent is high in dissolved arsenic and requires treatment before the wastewater can be discharged or re-used. Conventional arsenic removal relies on lime addition followed by calcium arsenate formation and precipitation as hydroxides. As an alternative, arsenic removal with sulphide precipitation is receiving more attention due to potential advantages of the technology. Process streams high in arsenic often contain concentrations of dissolved metals that may be selectively recovered during sulphidization, producing a product that can be reprocessed and reducing waste generation. This paper will review laboratory testing completed for arsenic removal through sulphide addition and precipitation of arsenic (III) sulphide in combination with metals recovery to offset arsenic removal costs.

Jan 1, 2014

By H. J. Ni, M. Y. Huang, S. W. Chen

The effects of several fluxes on purification, microstructures and properties of A00 aluminium have been studied. The experimental results and analyses indicate that many cracks and large porosities exist in the surface film above the melt purified by C2Cl6 and that the film is floe and mostly composed of AhO3 and pure aluminum, which carries many carbon particles and AlCh not fully volatilized. And then over 50% of the all-melting residue is pure aluminum, which is one of the major reasons for high melting loss. Moreover, because of a mass of gas bubbles and a state of seethe, there exist many inclusions which size is under l0µm in the microstructure of A00 aluminum purified with C2Cl6 or fluxes containing C2Cl6- With this purifying method, the aluminum crystal grains are extended along the radius that was observed firstly and the average crystal size of A00 aluminum are about 100µm~150µm. In addition, small size inclusions have little affected on tensile strength and micro inclusions under l0µm have little affected on elongation.

Jan 1, 2006

By Chen Feng

Compared to widespread successful deployment of robotic manipulators for repetitive and hazardous tasks in related industries such as manufacturing, the construction industry has achieved relatively limited benefits from robotics and soft automation. Unlike manufacturing, where robotic solutions benefit from the structured layout of the environment (e.g., factory assembly line), construction robots face unique challenges that arise from the rugged, dynamic, and unstructured environment of the work site, as well as the uncertainty and evolving sequence of occurring on-site events. This challenges any intended construction robots to not only replicate basic human motion, but also be capable of sensing and adapting to environmental changes, and making decisions based on the evolving state of the environment. Building upon recent advancements in robotic mapping, computer vision, and object recognition, the authors propose to introduce autonomous behavior at the basic task level for on-site construction robots to address these challenges in a flexible and extensible manner. This paper reports the outcome of the first phase of this research - a structured methodology for improved design and development of basic task automations - and focuses on algorithms developed for mobile robot navigation and relative pose estimation. The algorithms are implemented on a prototype mobile robotic platform, and evaluated in several experimental scenarios.

Aug 1, 2013

Agenda ? Introduction ? Inmet?s Operations and Closed Properties ? Inmet?s SECA Philosophy ? Inmet?s SECA Framework ? The Business Case for TSM ? Inmet?s TSM Reporting ? Inmet?s 2004 TSM Performance ? Opportunities for Improvement ? What Have We Learned From The TSM Process So Far? ? Summary Introduction ? Inmet has evolved into a strong TSM supporter ? Inmet is confident that TSM can be successfully and cost effectively implemented by smaller companies ? Inmet?s reporting on economic, environmental and social performance was raised significantly in our 2003 Annual Report ? a signal our commitment to good performance and improvement in these areas ? Our 2004 Annual Report has been further enhanced with the inclusion of our TSM performance

Apr 1, 2005

By J. Sugai

Formability of extruded round AZ31 magnesium alloy tubes with different manganese concentrations was evaluated by performing bending tests and measuring strain along the length of the tubes during the bending process. It was found that an increase in the manganese content from 0.3 % to 0.7% did not exert any significant effect on the values of yield stress, elongation, or compression to fracture. However the hardness tended to increase and the UTS decreased. The compressive ductility was significantly lower than tensile ductility for all manganese concentrations. Consequently, the formability of tubes decreased, causing cracks in areas where compression strain occurred during bending. It was also found that a larger strain occurred in the latter half of the region along the length of tube between the clamp-end and the tube-positioning block. Within this region, alloy tubes with higher manganese concentrations, 0.5 and 0.7 %, there was a clear strain peak within the strain profile, while for the 0.3 % Mn alloy, a more uniform strain profile was exhibited, indicating a more uniform deformation. This was confirmed by microstructural analysis of the specimens.

Jan 1, 2006

By L. Xia, B. Hart, K. Douglas

In the flotation of Rare Earth Element (REE) bearing minerals, oxalic acid is reportedly acting both as a depressant and pH modifier. Testing has established the significance of oxalic acid in the flotation process however its specific role in either the recovery or selectivity of REE over their gangue minerals is not well understood. Pulp pH reduction trials with alternative acids have not shown the same effect on the REE mineral recovery or the depression of gangue phases. This work examines the effect of oxalic acid on the surface of gangue minerals (quartz and carbonates (dolomite and calcite)) in a series of conditioning tests. Gangue surface analyses by TOF-SIMS indicate that oxalic acid inhibits the transfer of secondary ions generated during the conditioning process from one mineral phase to another. In this regard, the oxalate anion acts to fix ions in solution through chelation, limiting their participation in surface adsorption.

Jan 1, 2014

By Waldbillig. D.

A baseline of the poisoning effect of hydrogen sulfide (H2S) fuel impurities on solid oxide fuel cell (SOFC) anodes was developed using polarization testing. After the baseline behaviour was characterized, tests to study the effect of various H2S concentrations on the rate and amount of cell voltage degradation and recovery were performed. Attempts were made to improve the rate and amount of recovery by various methods. Testing was very reproducible, but significant electrochemical performance degradation was seen after all H2S poisoning tests even at an H2S concentration of 0.1 ppm. Degradation is initially quite rapid, but after a period of time the rate of degradation levels off. After poisoning was complete, the H2S flow was stopped and the cells were allowed to recover. Some recovery was seen after poisoning, but cell performance was never fully recovered.

Jan 1, 2005

By M. Takebayashi, M. Shingu, H. Nagai, T. Nakai, S. Asano

The Toyo Smelter and Refinery, owned by Sumitomo Metal Mining Co., Ltd. (SMM) is located in the coastal zone of Saijo City and Niihama City, Ehime Prefecture, Japan. The refinery has been producing copper, sulfuric acid, and precious metals such as gold, silver, and PGMs. Previously, the process of precious metals recovery was a combination of pyrometallurgy and an electro-refining process with the conventional cupellation for around 400 years. However, this process had some major problems such as non-efficient recovery of valuable metals, high environmental risk by pyrometallurgy, high cost for maintenance of equipment and so on. In order to solve these problems, a thorough hydrometallurgical process for precious metals refining using chlorine leaching technology was originated and developed by Sumitomo and thereafter commercialized in 2004 at Toyo Copper Smelter and Refinery. This new process enabled shorter-term recovery of gold and manpower saving, and occupational safety and working conditions have also been improved. Superiority over the existing hydrometallurgical processes was also confirmed, for example by the achievement of 99.99% pure silver production without an electro-refining process. This paper summarizes the hydrometallurgical technologies for precious metals recovery such as chlorine leaching of copper anode slime for silver recovery, solvent extraction (SX) for gold recovery, and ion exchange (IX) for PGMs recovery. It also presents a unique silver purification process. INTRODUCTION Sumitomo Metal Mining Co., Ltd. (SMM) produces copper, precious metals and rare metals as by-products at the Toyo Copper Smelter and Refinery, and nickel and cobalt at the Niihama Nickel Refinery. Precious metals contained in nickel ore are also separated and refined at the Toyo Refinery after concentration. SMM has been refining precious metals using the pyrometallurgical method. In recent years, we have revamped the separation and refining process of precious metals dramatically by making use of advanced hydrometallurgical and engineering technology developed in the company. In this paper, we introduce the history of development and techniques of this process, and also introduce in detail the technologies of gold refining, PGMs recovery, selenium recovery, and silver refining which have been particularly difficult to achieve.

Jan 1, 2019

By M. Moghadami

Design and construction of underground openings are associated with many uncertainties with regard to input data. In the construction process of underground openings various levels of risks exist and these affect the safety and profitability of the project. The development of underground openings can be broadly categorized into three major phases of data collection, design, and construction. A significant level of uncertainty is associated with some of the key parameters involved in the aforementioned development phases. Moreover, it is very difficult to evaluate and quantify the effects of uncertainties on the underground project construction process. Additionally, the interactions between important risk elements are typically not well understood. The intention of this study is to develop a general risk model for underground opening projects located in soils and weak rock masses. The goal of the research is to identify and quantify important geotechnical risk elements. Moreover, a weighting procedure will be proposed for the identified risk elements. Finally, all important risk elements will be assembled into a general model with emphasis on geotechnical parameters. The final objective of this study is to apply the proposed model to a real underground project scenario and verify it for actual field conditions. The proposed model, once calibrated properly, will provide a useful support tool for the decision making process.

Aug 1, 2013

By Ben Cottrell

In this paper technical drilling is referred to as the process of collecting engineering and metallurgical parameters for subsequent mine design considerations. Throughout the development of a mineral exploration property there are various opportunities to ?piggy-back? technical drilling onto the routine exploration drilling process, helping to reduce future costs and delays associated with re-drilling and missing information. This article is written from the engineers and metallurgists point of view, to outline some best practices for exploration borehole planning and technical data collection requirements.

Aug 1, 2013

By Baisheng Nie, Longlong Yang, Tao Yang, Wenjie Jia

"Gas adsorption in coal is an exothermic and physical process. Temperature might change during the dynamical process. In order to get the temperature variation of gas adsorption process, the experiment system which can test the temperature variation and analyze the thermal effect was established. Gas adsorption experiments under different conditions were done by using the test system. The results show that temperature increases during the adsorption process. It is an exothermic reaction process. Also, the temperature variation and the variation gradient increase with the increasing of equilibrium pressure. The temperature variation value is smaller if the experiment temperature is higher. The paper will provide basic experimental data for explaining gas adsorption mechanism better.INTRODUCTIONChina is the largest coal producer in the world while it also has the most serious coal mine disasters. According to the statistics, there are nearly a thousand coal mines in China including more than 110 the key state-owned mines risking to happen coal and gas outburst. Hundreds of coal and gas outburst occur each year which often causes serious casualties and economic losses (State Administration of Work Safety, 2007). With the continuing exploitation of the coal resources, the depth of the Chinese coal mines increases about 100 meters every year which causes the situation of gas accident becoming more and more serious (Xie et al., 2006).At present, the real mechanism of gas adsorption, desorption and the diffusion process in coal and the influence factor of it are not so clear. And because of the limit of prediction method and the technological level caused gas accident prevention theory and technology not so valid."

Jan 1, 2015

By A. Poor Zaeif Doost

With columns being installed in rougher section at Miduk Copper Complex, the rougher feed mainly reports to rougher-scavenger cells. To evaluate the efficiency of regrinding circuit, we conducted flotation experiments on samples of the feed and the products of the regrinding circuit. The grade difference of these products at 85% recovery was considered as the efficiency index. Results show that, with weight recovery of the rougher-scavengers the efficiency of the circuit increases. Exclusion of the rougher-scavenger concentrate from the feed to the regrinding circuit, resulted in an increase in the efficiency index from 10.12 to 17.6%.

Jan 1, 2012

By K. Nikkhah, N. Dhadli, G. Freeman

Ammoniacal pressure leaching operations have been in commercial use at the Fort Saskatchewan refinery of Sherritt International Corporation since 1954. Recent improvements have significantly increased the capacity of this circuit. The computer modeling of this process has proved to be a valuable tool in facilitating the evaluation of different operating scenarios in an effective manner. Reagent response in the ammonia leach of nickel and cobalt sulphides is examined using the dynamic process simulation capabilities of IDEAS(TM) software. The dynamic simulation enables accurate measurement of the sensitivity of the process to variables such as temperature, feed rate and ammonia concentration as well as compartmental analysis of metals concentration, pulp density, vent gas composition, and the formation of specific complexes. The complexity of the ammonia leach process makes it a logical choice for evaluation by computational analysis. The methodology for dynamic modeling of a pressure leach process is presented.

Jan 1, 2005

By Yan Jie

The oxygen-enriched bottom-blowing continuous converting process for copper matte was recently developed by the China-ENFI Engineering Corporation. The first commercial plant based on this technology was successfully commissioned at the Yuguang smelter in China in March 2014. The present paper describes this new continuous converting process and compares technical characteristics with other continuous converting processes including: Kennecott-Outokumpu flash converting, the Mitsubishi Process, the Noranda Converter and TSL continuous converting. The bottom-blowing oxygenated continuous converter with competitive capex and opex costs is seen as an attractive alternative to the Peirce-Smith converter.

Jan 1, 2014