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By BTrubT M

In the roast-leach-electrolysis process for the production of zinc, iron contained in zinc concentrates is converted to zinc ferrite during roasting. At Canadian Electrolytic Zinc (CEZinc), the Outokumpu Conversion process is used to simultaneously leach zinc ferrite and precipitate the iron as jarosite. These simultaneous reactions, while providing good process stability, require a compromise between optimum conditions for maximum zinc extraction and efficient iron precipitation. An improved conversion process has been identified which can achieve >99 per cent zinc extraction and more efficient jarosite precipitation to residual iron concentrations of

Jan 1, 1993

By J. R. Cobble

The Bureau of Mines has developed a process to improve the leaching kinetics of diffusion controlled systems. The system features the Bureau-developed turbomill, an attrition grinder which scrubs the reaction product coating away from the unreacted mineral grains during leaching. The system can be continuously operated at any temperature up to the boiling point of the leaching agent. This paper describes the research on the dissolution of chalcopyrite with acidified ferric sulfate which forms a sulfur product on the unreacted chalcopyrite surface. This method is a hydrometallurgical alternative to chalcopyrite smelter technology which eliminates S)2 emission problems with its associated costs. Batch testing at 90? C with the chalcopyrite/ferric sulfate system resulted in better than 99-pct extraction of copper. At an optimal energy consumption of 1,520 kW h/st, 95 pct of the copper was extracted. Recent work has been directed to development of a continuous system and SX/EW treatment of the resulting pregnant liquor from the chalcopyrite/ferric sulfate leach.

Jan 1, 1991

By J. Kang

To obtain microbial cultures with the ability to efficiently leach copper ion from chalcopyrite, microbial samples from acid mine drainage sites were mixed and then subjected to mutation using sodium nitrite (NaNO2), diethyl sulfate (DES), ultraviolet light (UV) and their combinations. Mixed cultures with a much stronger ability to leach copper ion (identified as mixed cultures A, B, C, D and E) were obtained by screening on leaching media. Leaching tests showed that mixed culture E had the best leaching performance and increased the Cu2+ content by 120.5% in 20 days, compared to a control without mutation treatment. Mixed culture E grows well on Leathen leaching medium supplemented with Cu2+ (at a final concentration of 32 g/L), reaching 3.2 × 107 cells/L after 15 days, while the unmutated control culture cannot survive beyond 15 days, indicating that mixed culture E is more tolerant of high concentrations of Cu2+. In addition, continuous leaching by mixed culture E is very effective at a pulp density of 1%. These results suggest that it has the potential for industrial applications.

Jan 1, 2008

By M. Saghaeian, R. Hejazi, R. Barreiro, M. Tavousi, M. Ahadi, O. Asghari

"Banded iron formations are the major iron source for producing high grade concentrate. BIF are generally lower grade and more difficult to extract. In order to know how best to process BIF ore, it require comprehensive knowledge on ore bodies even in the early stages of the mining process. Geometallurgy combines geological and mineral processing information and allows for higher flexibility in response to changes in the plant feed when mining different parts of the ore. This can lead to economic benefits, owing to improved plant operation, yet is time consuming and correspondingly costly. The main focus of this paper work has been to develop a comprehensive geometallurgical testing framework for developing Yogi BIF low grade magnetite deposit located at Western Australia. In order to provide successful geometallurgical mapping, was collected data from several different disciplines (geology, chemistry, mineralogy) and parameters (physical properties, metallurgical response and geotechnical measurements) during drilling activities and test work. The investigation shown magnetic separation behavior of material had high variation and is most important element in the proper design of ore beneficiation plant. This paper provides an improved and efficient magnetic separation test methods used for the investigation of separation behavior and variability of the Yogi Ore deposit and evaluates their applicability and potential in the geometallurgical context. In this paper a small-scale magnetic separation has been developed that allows estimating from single pass separation test using small amounts of sample material. Verification of the evaluation method and validation was done with different mineral systems."

Jan 1, 2018

By Junhyun Choi, Allan Gomez-Flores, Chonbuk National University, Siyoung Q. Choi, Gahee Kim, Seungkon Kim

In this study, to confirm the effect of depletion attraction on the flotation, we theoretically and experimentally investigate the effect of the depletion attraction force on flotation. While varying the concentration of the depletion agent (polyethylene glycol), three different systems are studied: pure malachite, pure silica, and a 1:1 mass ratio of malachite and silica binary system. We find that recovery increases significantly as the concentration of the depletion agents increases for all three systems, as the depletion agent facilitates the adsorption of the particle on the bubble surface. However, the recovery suddenly decreases in a certain concentration range, which corresponds to the onset of the decreased surface tension when high concentrations of the depletion agent are used. This non-monotonic overall recovery trend implies the surface adsorption of the depletant on a surface. The decreased surface tension of the air/water interface suggests that the recovery rate is lowered due to the adsorption of the depletion agent to the bubble surface, acting as a polymer brush. Based on our observations, we conclude that the depletion force can greatly improve particle adsorption, as predicted in the accompanying theory paper, while simultaneously the adsorption of the depletion agent on the bubble surface plays an important role because it hinders particle adsorption. We also perform experiments in the presence of a small amount of a collector, sodium oleate. An extremely small amount of the collector leads to the increase in the overall recovery, which eventually reaches nearly 100 percent. Nevertheless, the grade worsens as the depletant provides the force to silica particles as well as target malachite particles.

Jan 1, 2016

By Roberto C. G. Oliveira, Scott C. Brown, Brij M. Moudgil

"The wettability or surface energy of particle surfaces dictates a number of multiphase ensemble interactions that have a significant impact in mineral processing. Dispersion, bulk powder handling and flotation are just a few of the processes that are largely influenced by the degree of hydrophillicity or hydrophobicity on particulate surfaces. Because of the importance of surface wettability, a number of simple, precise and accurate techniques for accessing surface wettability or contact angle on macroscopic flat surfaces have been developed. However, these techniques cannot be directly applied to the particulate surfaces that are often in query. Though a number of techniques are available for accessing the wettability of particulate surfaces, these methods are either relative, application specific or prohibitively tedious. In the present study, key features of existing techniques are combined to formulate an improved method to delineate particle wettability that is simple, versatile and capable of providing reproducible measurements in an industrial environment.Through the use of an inert adhesive and an inert macroscopic surface as a support, it is illustrated that precise measurements of particle wettability are obtainable under suboptimal or ‘shop floor’ conditions. The measurement of the maximum external meniscus height formed between a test liquid and a particlecoated rod is employed to estimate phenomenological contact angles on particles ranging form a few nanometers to several hundred microns in size."

Jan 1, 2003

By J. Drelich, M. Pawlik

An improved experimental procedure to measure contact angle has been consolidated with coal surface preparation involving polishing with abrasive paper, alumina powder, and a cloth, followed by ultrasonic and mechanical cleaning. Specifically, the captive-bubble measuring technique has been compared with the sessile-drop technique and the former has been recommended for the examination of the hydrophobic properties of coal surfaces. Results of the research program, which is currently under way, on the examination of the effect of the nature, amount, size, and distribution of mineral inclusions in coal, on its wettability are briefly reviewed.

Jan 1, 1999

By J. Drelich

An improved experimental procedure to measure contact angle has been consolidated with coal surface preparation involving polishing with abrasive paper, alumina powder, and a cloth, followed by ultrasonic and mechanical cleaning. Specifically, the captive-bubble measuring technique has been compared with the sessile-drop technique and the former has been recommended for the examination of the hydrophobic properties of coal surfaces. Results of the research program, which is currently under way, on the examination of the effect of the nature, amount, size and distribution of mineral inclusions in coal on its wettability are briefly reviewed.

Jan 1, 1999

By Soumitry J. Ray

Poor visibility of powered industrial vehicles, such as forklifts, used in industry is often the cause of accidents that include pedestrians. Current standards allow up to 20 % non-visible regions for forklifts where measurement of these regions is performed by using lamps. A collaboration of research organizations, including National Institute of Standards and Technology, Georgia Institute of Technology (NIST), and Direct Dimensions, has been evaluating advanced methods for measuring a forklift operator?s visibility. These methods can potentially improve visibility standards. They can also help forklift and sensor manufacturers to determine (1) how visibility-assist sensors and algorithms can be designed and (2) where sensors can be mounted on forklifts. This paper includes explanation of visibility measurement experiments performed and results, associated language suggested to standards organizations, and a prototype design for measuring the visibility of forklifts automatically.

Aug 1, 2013

By W. L. Dalke

The Minntac complex is a facility for production of iron ore pellets located on the Mesabi Range at mountain iron, Minnesota. It consists basically of a mine, crushing plant, concentrator, and a pelletizer producing twelve and one-half million tons of pellets annually. This paper deals with some of the aspects of the grinding circuits; but prior to that discussion, it might be well to briefly describe the flow of material in the operation. The crude ore, containing from 20% to 25% magnetic iron, is mined by 14-yard electric shovels. .the blasted ore is loaded directly into 50-yard side dump railroad cars and hauled to the crushing plant. Crushing is done in three stages, originally, two 60" primary crushers; four 7-foot standard secondary crushers; and six 7-foot short head tertiary crushers were installed, when the plant was expanded to double its capacity, five secondary and ten tertiary crushers were added. These were duplicates of the original 7-foot standard and short head crushers used in the original construction, there was no expansion of the primary crushers but a one-half-million-ton surge pile of tertiary crusher feed was added.

Jan 1, 1976

By R. Dawson Hall

LONG regarded as nearly worked out, the anthracite region still shows promise of a hundred years of life, for means are being found to get bottom, top, pillar, and other coal that earlier generations disregarded as too expensive to mine. Rock drivages and, still more, machinery are making it possible to get such coal. Mechanical methods enable the owner of thin beds to mine these with profit, and the miner recognizes that he must permit the use of machinery or the inexorable laws of economics will deny him opportunity to work. E. L. Dana, Jr., well outlines this situation, which in the past year became definitely established. Stripping also is recovering, safely and inexpensively, coal that past generations regarded as too hazardous and costly for mining.

Jan 1, 1935

By Albert J. Shohet

The increasing scarcity of bentonite coupled with the potential of improved pellet strength have created a need for understanding the effects of thorough bentonite dispersion in taconite concentrate. It has been known for more than a decade that under certain conditions substantial savings of bentonite are realizable by using thorough mixing of bentonite as compared to poor mixing. Extensive work done by J. O. Zetterstrom l at the Univer¬sity of Minnesota indicated the effect of thorough bentonite mixing in a controlled laboratory testing. Commercial hardware was not available at the time Zetterstrom1 paper was published and not much work was done until R. L. Stone, J. M. Karpinsky2, did work with Muller mixing. Nabush 3 worked with the pugmill principle, and Hoogovens 4 and Robe River 5 used the fluidized bed principle. It was very hard to convince iron ore industries to improve the mixing of Bentonite and taconite for the following reasons: A. The initial capital investment for improved mixing equipment; B. The relatively low bentonite cost a few years back, which was not enough to justify new equip¬ment investment;

Jan 1, 1976

By B. Qiu

The large surface ground movements induced by underground mining could threaten the safety of the pipelines laid across the subsidence-prone area. Existing analytical methods for the stress analysis of buried pipeline over mine subsidence area were based on the assumption of ?thin? pipeline, which limited their applicability. This paper presents the improved model with the capability to determine the stress distribution of the ?thick? pipeline. The pipe-soil interaction in this model was also updated to adapt various pipe soil contact conditions. In addition, the time-dependent effects of dynamic subsidence effects were also added to the model. A case of protecting a long section of a buried large-diameter pipeline over two longwall panels in a shallow mine is shown. The stress distribution along the pipeline is determined and the overstressed sections are identified. A partial uncovering plan was developed based on the predicted stress and complicated terrain at the site.

Aug 1, 2013

By Wei Luo

Nickeliferous laterites were characterized by particle size analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX), Fourier transform infrared (FTIR) spectroscopy and thermal analysis. Results showed that the laterites consist mainly of nickel-substituted lizardite with cobble-like morphology and traces amounts of magnetite and phlogopite. As fluoride ions can react with silicon in the lizardite crystal structure and form metal-fluoride complexes, as well as increase the equilibrium constant of the lizardite dissolution in acid solution dramatically, the addition of minor fluoride salts (0.2wt.% NaF) gave a markedly enhanced metal extraction rate (Ni 81.7% and Co 52.3%) under the experi-mental conditions of particle size d50= 25 µm, 10% (v/v) H2SO4, reaction time 2 h, reaction temperature 90°C, liquid-to-solid ratio 3 mL g-1 and stirring at 500 rpm compared with H2SO4 alone (Ni 69.6% and Co 30.8%).

Jan 1, 2010

To be able to continuously monitor the noise to which underground workers are exposed as a better way to help prevent hearing damage. The Approach: The Bureau of Mines has developed a Time-Resolved Audio Dosimeter which can be worn by miners to record noise level every 30 seconds and store It in a miniature solid state memory. Figure 1 is a photo of the dosimeter. [ ] How It Works: Acoustical noise is picked up by a micro-phone and fed to a sound level meter which produces a d-c voltage proportional to the A-weighted sound pressure level. (As specified by federal regulations, the A-weighted sound pres-sure level approximates the response of the ear by discounting the higher and lower frequency components of the noise.) This d-c voltage controls an oscillator which, together with related circuitry, produces a pulse train having a frequency that's proportional to the noise level.

Jan 1, 1975

By Jeff Smith

Agenda About NORTHPARKES The NEED The INITIATIVE The SEARCH The PRODUCTS The SOLUTION The RESULTS The Northparkes copper-gold mine in Central Western NSW commenced operations in 1994. Copper concentrate is produced and shipped to smelters in Japan, China & India under long term contracts with spot sales to other Asian countries.

May 1, 2006

By Scott, Turner

IN 1933, the monetary metals were produced in a ratio of 6.7 oz. of silver to 1 oz. of gold, the lowest relatively for silver since the period from 1851 to 1865. At the beginning of that period, the virgin placers of California -and Australia began producing almost simultaneously; in consequence, there was an abrupt fall in the high silver side of the ratio that had prevailed through the centuries after America was discovered. The output from the Comstock and other silver-bearing lodes, located a decade after this influx of new gold began, soon restored the production ratio to its former proportion, that is, a relatively large weight of silver compared to gold.

Jan 1, 1934

By Colleagues from Process and Operation departments, Guy Chevalier

"QCM's pellet plant, located in Port-Cartier, Quebec, produces up to 8.6 million tons of iron ore pellets annually. Four different types are produced: three for blast furnace operations and one for direct reduction furnaces. The paper presents the scientific approach that led to the installation of new process equipment to improve the reducibility of direct reduction pellets (DR pellet). The findings, the equipment selection and some post start-up modifications are presented.This low silica DR pellet is used in Midrex and HyL shaft furnaces. A good DR pellet has to meet strict chemical, physical and metallurgical specifications. An important metallurgical property is its ability to release oxygen when exposed to reducing gases. Considering that the market for DR pellets is expanding and being aware that reducibility is critical for our clients, a program to improve the latter was undertaken. Test work showed that one factor which has a negative effect on reducibility is the proportion of particles larger than 75 microns. Knowing that the best way to reduce the amount of coarse particles was to close our open grinding circuits, we began evaluating the most suitable classification equipment applicable to our process operations. We settled on hydro-classifiers based on their very sharp cut and their low operating costs. In light of the hydro-classifiers performance it was also decided to replace the hydro-cyclones of an already closed circuit.INTRODUCTIONAt the Québec Cartier Mining pellet plant, continuous improvement programs are aimed at increasing levels of consistency and improved chemical, physical and metallurgical properties. This is being accomplished while still maintaining pellet plant production volumes to satisfy market demands.QCM produces three types of pellets for blast furnace use: acid pellets, designated as ""BHF"", fluxed pellets, designated as ""BAF"", and low silica fluxed pellets, designated as ""BSA"". For direct reduction, a low silica acid pellet or DR pellet, designated as ""BBS"" is produced. This low silica DR pellet is used in Midrex and HyL shaft furnaces.The demand for DR pellets has been increasing during the last few years and is believed to continue so in the future. Wanting to be present in this growing market QCM found that it would be essential to work at improving its DR pellets quality. Efforts have been focused on improvements in three areas: SiO2 reduction, elimination of sticking and increasing reducibility. Improvement programs have begun with laboratory research followed by plant trials and full-scale implementation as a cooperative effort among QCM, COREM, and key customers."

Jan 1, 2002

By J. G. Schofield, C. G. Tan, R. J. Ord

"Most electric furnaces in the nickel and copper smelting industries are still fitted with conventional electrode holders which consist of water-cooled electrical contact clamps and a pressure ring. The water cooling exerts a significant cooling effect on the electrode column. The importance of controlling the temperature of the Soderberg electrode paste at the contact clamp area is examined, using in-plant experience and computer simulation of the paste melting and baking process. In addition to the effect of water-cooling, the effect of other variables, including the mantle air temperature, the electrode current, the furnace freeboard temperature and the electrode slipping rate are discussed. Ways in which the variable heating conditions in the paste melting zone can be controlled are outlined.IntroductionIn most non-ferrous electric smelting operations, the breakage of Soderberg electrodes is an infrequent, isolated occurrence. Occasionally, however, a rash of breakages may be experienced on a particular furnace for what appears to be no obvious reasons. The extent of the breaks may not exhibit a uniform pattern; sometimes the break may be less than half a metre above the electrode tip; at other times it may be at or just below the roof level. The latter type of break is, of course, the most dangerous since it is closest to the non-baked, weak portion of the electrode paste column. No matter where the breaks occur, they result in abnormal furnace power, charging and tapping conditions and loss of production while the new electrode section is slipped and baked. On a six-electrode furnace, breakage on one electrode has the immediate effect of reducing the total furnace power by one-third. On a three-electrode furnace, the effect is more drastic, one half of the power being lost."

Jan 1, 1995

By Jim Frazier

Tradition has often dictated low design load stresses on piles. Such traditions often developed prior to modern static or dynamic pile testing methods and perhaps result from a few limiting situations. These low stress limits were then broadly applied, even in cases where the piles could carry substantially higher loads. With sufficient testing to prove the design, higher design loads may present significant overall savings to the project owner. The cost of the testing then becomes an insignificant cost compared to the potentially great benefit of increased pile loadings. To confirm higher load possibilities for driven piles, the pile is tested either statically or dynamically. Further savings and increased testing efficiency result from remote dynamic pile testing. This paper presents a project where design stresses were considerably increased as a result of additional testing and use of remote dynamic pile testing equipment.

Jan 1, 2002