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By A. L. Engel

[This report describes preliminary tests of samples from six deposits of oxidized copper ores .in Nevada. The tests for the most part were confined to laboratory-scale acid leaching to extract the copper.'The exceptions consisted of flotation tests to demons' ate the possibilities of treating the ore by that method. The samples tested were representative of oxidized copper ores from six counties in all parts of Nevada. The results obtained by the preliminary tests described were indicative of the extractions of copper to be expected, In the five leaching experiments, the approximate consumption of acid was also indicated.]

Jan 1, 1953

By Fuqiang Guo

Scorodite (FeAsO4, 2H2O) is suitable mineral carrier for immobilization of arsenic-rich wastes. Its stability is, however, highly pH dependent (typically at 4 ≤ pH ≤ 7) and satisfactory only under oxic disposal conditions. In thiswork an encapsulation process using mineralized gels of aluminum hydroxy-oxides is developed to enhance the stability of scorodite under wider pH and redox potential range conditions. The encapsulation involves blending and ageing of synthetic scorodite produced by McGill’s atmospheric scorodite process with aluminum hydroxyl gels derived from controlled hydrolysis of aluminum salts. The amorphous hydrolyzed Al-gel encapsulates the scorodite particles,which upon short-term aging transforms into crystalline Al (OH)3/AlOOH mineral phases providing a robust protection microscopic barrier. Long-termstability testing demonstrates the encapsulation systemto be highly effective in suppressing arsenic release under either oxic or anoxic (100 mV < Eh < 600 mV) potential and neutral-alkaline pH (7 ≤ pH ≤ 9) ranges.

By B. A. Filas

Stabilizing fine coal refuse ponds for reclamation at Monterey Coal Company&apos;s No. 1 Mine has been difficult. Entrained water in the stored refuse causes liquefaction as reclamation caps are placed, resulting in additional material requirements than originally projected to stabilize the pond surface. Laboratory results indicate that in-place refuse densities may be substantially improved at No. I Mine by converting from a single-point to a managed slurry distribution system. Increased densities result in improved storage efficiency, less entrained moisture and a more stable refuse mass, thereby providing an improved working surface for reclamation and improved post-closure cover stability.

Jan 1, 1993

By T. C. Bibb

Longwalls using shearers in seam heights of less than 1.2 m (48 inches) are relatively rare in the U.S. Westmoreland Coal Company is currently operating a shearer-equipped longwall at a cutting height of 1.17 m (46 inches) in its Bullitt Mine. This face has averaged 2795 metric tons/day of operation since its startup on April 3, 1984. Longwall productivity in thin seams is substantially impacted by equipment reliability and availability of useable working room for travel and access. This paper addresses the design criteria used in selecting this face equipment, with the goal of maximizing these two parameters. Equipment discussed includes shearers. face conveyor, shields, stageloader, and emulsion system.

Jan 1, 1985

By Sirish L. Shah

It is now common to have archival history of thousands of sensors sampled every second over long time. Yet we frequently have process engineers complain:??.We are drowning in data but starving for information??. How can these rich data sets be put to use? This paper addresses the issue of information and knowledge extraction from data with emphasis on process and performance monitoring including fault detection and isolation. Most of the major plant, factory, process, equipment and tool disruptions are avoidable, and yet preventable fault detection and diagnosis strategies are not the norm in most industries. It is not uncommon to see simple and preventable faults disrupt the operation of an entire integrated manufacturing facility. For example, faults such as malfunctioning sensors or actuators, inoperative alarm systems, poor controller tuning or configuration can render the most sophisticated control systems useless. Such disruptions can cost in the excess of $1 million per day and on the average they rob the plant of 7% of its annual capacity. Over the last decade the fields of multivariate statistics and data visualization and analysis methods have merged to develop powerful sensing and condition-based monitoring systems for predictive fault detection and diagnosis.These methods rely on the notion of sensor fusion whereby data from many sensors or units are combined with process information, such as physical connectivity of process units, to give a holistic picture of health of an integrated plant. Such methods are at a stage where these strategies are being implemented for off-line and on-line deployment. This article attempts to outline the field of sensor fusion - the application of signal processing methods, in the temporal as well as spectral domains, on a multitude and NOT singular sensor signals to detect incipient process abnormality before a catastrophic breakdown is likely to occur Keywords: Process analytics, process and performance monitoring, multivariate statistical analysis, sensor-fusion

Sep 1, 2012

By M. C. Mound

A recent development using XRD techniques, a unique fixed detector, specifically permitting full mineralogical information simultaneously for the first time, specially designed sample preparation and presentation system and Rietveld codes provide a continuous real- time analysis on the true contained mineral polymorphic composition of powder streams such as ore materials, cement, ground clinker or any other mineral stream conducive to XRD analysis. There are several COSMA systems currently operating in the US, Canada, Italy and Australia, proving service and reliability of this concept. The mineralogical information generated continuously in real time is used for automated efficiency, product quality and reduces costs. Quantitative Phase Analysis information is transmitted to the plant DCS via Modbus over RS422 or ethernet. Some limited information is stored in the on-board computers for optional future use at the operator?s option.

Jan 1, 2010

By Leopoldo Gutierrez, Esau Arinaitwe, Marek Pawlik

"The effect of various polymers, including: anionic carboxymethyl cellulose (CMC), polystyrene sulfonate (PSS), humic acids (HA) and non-ionic hydroxypropyl cellulose, on the wettability of Athabasca bitumen was evaluated through dynamic contact angle measurements using the captive bubble technique. The tests were carried out as a function of pH at a constant ionic strength (0.01 mol/L sodium chloride). The evolution of the three-phase contact angle between the solution, bitumen and an air bubble was followed as a function of time over a period of ~6 minutes. The contact angle data were modelled using a first-order kinetic equation. The results were analyzed in terms of the initial contact angle, the evolution rate constant, and the steady-state contact angle value. In the case of anionic polymers, a pronounced decrease in the initial contact angle value was observed at pH 3. Under acidic conditions, there was no significant effect of CMC observed on the steady-state contact angle value but PSS and HA significantly decreased the steady-state contact angle value. At pH 8.5. the anionic polymers did not affect the wettability of the bitumen surface but they significantly decreased the contact angle evolution rate. These results suggested that CMC is not capable of permanently lowering the hydrophobicity of bitumen, and the polymer only slowed down the evolution of the contact angle to the steady-state value. The results also showed that polystyrene sulfonate and humic acids were capable of making bitumen hydrophilic but only under acidic conditions. Only hydroxypropyl cellulose (HPC) produced a large decrease in the steady-state contact angle under alkaline conditions (pH 8.5). The kinetics of contact angle evolution in the presence of HPC was also drastically lowered. The results were discussed in terms of the chemical composition of the polymers and their different affinities towards the bitumen surface."

Jan 1, 2014

By Roméo Roussin

"The yearly production from the Asbestos Hill pit is 1,550,000 tons of asbestos ore, with a yield varying between 18 and 20 % . The orebody was exposed at the top of a hill, and initial production started without having to remove any overburden. The projected ratio of barren rock to ore, based on the present orebody, was 2 to 1. However, as it was necessary to push back the upper benches, this ratio has changed to 3 to 1. The final pit will be 2,300 feet long by 1,000 feet at the longest and widest points. The final depth will be 680 ft. A pit slope stability study was carried out and an average wall angle of 60-70 degrees must be maintained. Preshearing of final pit limits will produce good wall stability. Permanent access ramps will be 60 ft wide, with an 8 % maximum grade. Geological conditions and the low rock temperature are the major causes of the operation's drilling and blasting problems."

Jan 1, 1976

By B. Nanthakumar

The impact of stockpile oxidation on chalcopyrite was studied through collectorless and collector-induced flotation conditions. In both cases, the Cu grade-recovery performance of stockpiled ore showed relatively poor concentrate grades with respect to that of a fresh sample. However, the oxidation had a minor effect on chalcopyrite recovery itself. The poor concentrate grades resulted from dilution effect primarily by excessive flotation of pyrrhotite. Size-by-size analyses indicated that for the collectorless flotation, the recoveries in the coarse and fine particle-size regions, were higher for fresh ore than for stockpile sample. A greater impact was seen in the coarse size regions for both types of sample, compared to the collector-induced case. The Cu recoveries showed a remarkable increase in the coarse size range for both samples when a collector was used. However, the case for stockpile sample was a marginally higher compared to the fresh sample. This difference has been offset by an opposite trend that was observed between these two samples in the fine size region. It is concluded that in contrast to the case with nickel-bearing sulphides, stockpiling conditions do not show a significant adverse effect on behaviour of chalcopyrite due to its strong floatability, regardless of oxidation.

Jan 1, 2007

The Boliden Aitik concentrator in Sweden processes 2,000 tph of low grade copper ore. The plant consists of five grinding lines feeding four bulk flotation banks with a scavenger concentrate regrind mill, and a column cleaner circuit with a regrind mill. The authors installed a model-based expert, optimizing control system to maximize copper recovery in the bulk flotation circuit while maintaining an appropriate copper grade in the cleaner feed. The optimizing control system uses on-line assays and calculates and implements set points for cell pulp levels, air rates and reagent addition rates. It combines the power of a dynamic population balance model which estimates mineral liberation in each stream, an optimizer which computes appropriate set points and a rule-based module which implements the strategy. The benefits have been evaluated over three months. The model-based expert, optimizing control system generates a measurable increase in copper recovery, around 0.5 per cent and an optimized bulk concentrate grade. The need to maintain the optimizing control system and other practical aspects are discussed.

Jan 1, 1998

By Lawrence A. Roe

This paper describes research and development efforts leading to a wet process for the beneficiation of Western talc ores in which the values are primarily present as soft, platy talc mineral. The mineralogy of the ore, as it relates to the logic of utilizing an uncomplicated, attrition-scrubbing sedimentation process is described. Bench-scale laboratory testwork and a pilot-plant test program are described. The pilot-plant program included production of several tons of products. The thickened talc slurries were very difficult to dewater prior to the drying step. Dewatering difficulties were overcome by use of a high-speed centrifuge. The centrifuge cake was dried either by tray, flash or spray drying. The successful use of one high-grade talc product as titanium dioxide extender in paper is discussed. The talc product has extremely low abrasion values, an important characteristic for minerals used in paper manufacture. It is concluded that this wet process for soft talc ores is capable of producing high-purity talc products for paint, paper, cosmetics and other industrial uses re-quiring very pure soft talc.

Jan 1, 1972

By C. D. M. Chisholm

IN discussing stope filling, or backfilling, at the Sullivan mine, at Kimberley, B.C., a brief description of the problem will first be presented. The Sullivan orebody is a replacement in quartzite, with the ore con-forming, for the most part, with the bedding. The dip of the vein, apart from local irregularities, averages about 15 degrees near the outcrop in the southwest section of the mine, and steepens to almost 40 degrees at the northeast end of the mine. The thickness varies from a few feet to over 200 feet at the widest sections. The mineable length along the strike has averaged about 4,000 feet between the 4,600 and 3,900 levels-the section under discussion in this paper. To date, 28,000,000 tons of ore have been mined by the room-and-pillar method. Prior to 1930, all ground opened up had been supported by ore pillars, left during mining operations. From that time, the recovery of the ore from these pillars has been given serious consideration. Backfilling, as being carried on today, is the result of this study and is being done for two reasons: (1) to allow extraction of the ore pillars, and (2) to minimize subsidence of the hanging-wall rock, except where forced caving is found desirable. PRELIMINARY DEVELOPMENTS LEADING TO BACKFILLING When the Sullivan orebody was first opened up, early in the century, there appeared to be low-grade sections of the vein sufficient in extent to serve as permanent support for the roof. However, as mining extended into sections of the vein that showed continuous ore over greater areas, wooden cribs, filled with waste and low-grade ore, were erected. In some stopes, these cribs were as large as 40 ft. by 100 ft. in plan and from 50 ft. to 60 ft. in height, but it was soon realized that this method of support was inadequate. As mining progressed, it was found necessary to leave ore pillars, which eventually became the sole system of support. At first, these pillars were left at irregular intervals, but later they were laid out at definite locations on the mine plans, and these locations were adhered to as closely as mining would permit.

Jan 1, 1941

By R. Phillips

The low concentration of diamond in workable deposits requires very large samples for grade estimation, and results, even then, may be erratic and difficult to interpret. Although the Poisson probability distribution cannot accurately describe the occurrence of diamond, it is suggested that it gives a better estimate of grade than conventional methods, even from single samples. Examples illustrate the simple calculation required.

Dec 1, 1971

By Lucia Kuizon

The Antimony RARE II area is underlain principally by Mesozoic igneous rocks associated with the Sierra Nevada batholith. The San Andreas fault zone is near the southern boundary. Metallic mineral deposits are associated with the fault zone. These deposits were formed from magmatic solutions, and tend to be along shears and fractures within the country rock. Marble and dolomitic marble deposits occur in Paleozoic roof pendants or inclusions in the Mesozoic intrusive rocks in the area (Troxel and Morton, 1962, p. 52).

Jan 1, 1982

By F. F. Hintze

In the group of minerals used in making this study, the cyanite is associated with quartz, mica, and feldspar in the schist. The amount of quartz is variable, but it is always an abundant mineral. Both large and small crystals of quartz occur in irregular masses, rarely ever showing crystal outline. Mica is of the clear and dark varieties, the larger crystals being dark as a rule, and the finer crystals of light color. The present mineralogical composition of the mina is rather variable, as most of the original biotite and muscovite have suffered alteration, and much secondary mioa is present as a result of alteration of the original mica and other minerals present, especially the larger cyanite crystals. A large part of the mica now found in the ore is chlorite, with varying amounts of Jefferisite and others, especially sericite. These are in the form of aggregates, or felt-like intergrowths filling the spaces between the quartz, cyanite, and feldspar.

Jan 1, 1931

By John O. Marsden

"This article is an attempt to capture a presentation given at the 2016 SME Mineral & Metallurgical Processing Division (MPD) Luncheon held on Feb. 24, 2016, in Phoenix, AZ. It was presented as a tongue-in-cheek, lighthearted view of several of the issues facing our industry, while identifying some of the challenges and opportunities available to new engineers entering the industry today.Disclaimer• What you are about to read includes personal preferences, biases and occasionally arbitrary opinions.• Some readers may have dissimilar opinions on the contents and/or the rank order of the lists.There are eight top ten lists offered in this article: (1) Industry realities (2) Things a metallurgical or mineral process engineering graduate should do (3) Books every metallurgist should have on their shelf (4) Things I wish I had known (5) Legends of metallurgy (posthumous, with highlights) (6) Things we’ve forgotten (7) Mineral processing innovations of the past 20 years and, finally, (8) The future? For some items, additional context or clarification is provided after the item, while for other items no further explanation is warranted and none is offered. Top 10 industry realities1. Metal price cycles.2. Bigger is better (except when it isn’t).3. Ore grades declining across the board of metals/commodities.4. Ores becoming more complex.5. Three-fold increase in capital costs between 2004 and 2015.6. Three-fold increase in operating costs between 2004 and 2015.7. Less capital availability/challenging financial markets.8. Environmental constraints increasing.9. Socio-political constraints increasing.10. The mine manager is always impossible to work with.As Table 1 shows, there was more than a three-fold increase in gold operating costs between 2004 and 2014. The increases for copper, iron ore and other commodities were similar."

Aug 1, 2016

The mining of high-grade narrow vein deposits is a predominant field of activity in the precious metal sector. These types of deposits are located throughout the globe and have a significant presence in mining operations. The principle factor that has undermined the profitability and effectiveness of mining such ore zones is the substantial dilution that occurs when blasting with explosives during extraction. In order to minimise ore dilution, the thermal fragmentation mining method enables the operator to extract a narrow mineralised corridor, 30 cm to 1 m wide (according to the true width of the ore vein). By inserting a strong burner powered by diesel fuel and air into a pilot hole previously drilled directly into the vein, a thermal reaction occurs spalling the rock and enlarging the hole to 30 - 100 cm in diameter. This patented method produces highly concentrated ore, resulting in 400 - 500 per cent less dilution when compared to conventional mining methods. The mining method was conceived with the aim of mining ounces, not tonnes. This method of extraction, reduces the environmental impact of mining operations since much smaller quantities of rock are displaced, stockpiled, and treated using chemical agents. The fully mechanised equipment operated by a two-person team, maximises the effectiveness of skilled personnel, increases productivity, and reduces risks of injuries. Important economic benefits are generated for large- and small-scale mining operations alike. For large-scale operations, the mining method increases mining reserves, lowers the cost per ounce, and increases the total profitability of existing mine operations. The method also significantly lowers costs and risks of developing and mining small-scale deposits, requiring less investment capital, shortening the payback period, thus reducing the lending risk.&nbsp; Combined with a small modular processing unit able to process between 100 - 300 tons per day, the method substantially lowers the financial break-even point for small-scale mining operations in a narrow vein environment. The company has been working with the technology at its Rocmec 1 mining site; results achieved and future developments are discussed.

Jan 1, 2008

By D Maconochie, S Pradhan, M Reed

The Waterview Connection will provide a high-quality strategic alternative to State Highway One and complete Auckland’s Western Ring Route connecting State Highways 20 and 16. The project includes twin three-lane motorway tunnels 2.4 km long and 13.1 m internal diameter (ID). The tunnel construction started in November 2013 using the tenth largest earth pressure balance (EPB) tunnel boring machine (TBM) in the world. The tunnels will pass beneath urban and greenfield areas as well as a major local arterial road. The project is being delivered by an alliance of constructors, designers and the New Zealand Transport Agency. This paper describes some of the key innovative and cost saving design solutions that have been achieved through collaboration in the alliance environment with the construction team, owner’s verifier, the segmental lining precast suballiance and the M&amp;E suballiance for the underground works. The key design elements of the tunnel comprise a three-lane roadway, invert culvert and backfill, precast segmental lining, sixteen mined cross passages including a low point sump cross passage and steel segments for opening to the cross passages. This paper reviews interdisciplinary design integration and the economies achieved in the permanent works tunnel lining design, including reduction in lining thickness and optimising reinforcement, cross passage separation of 150 m, efficient design of the invert culvert and backfill design, main drainage pipe and low point sump. The paper also describes the attributes of the TBM and the invert culvert construction methodology.CITATION:Pradhan, S, Maconochie, D and Reed, M, 2014. Tunnel design in an alliance for Waterview Connection, New Zealand, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 425–430 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By D. Tao

Reverse cationic flotation is the most widely utilized flotation method for concentrating iron ore. In this process, quartz is often floated with ether amines (R?(OCH2)3?NH2) partially neutralized with acetic acid. However, it is well known that the cationic flotation of quartz does not work well if a certain amount of slime is present in the ore slurry. To improve flotation performance, starch is often added to the flotation feed to selectively flocculate and depress the iron minerals and sodium silicate is used to disperse the silica gangue. The present study was conducted to improve the efficiency of iron ore flotation by the use of a new type of depressant for clay and iron minerals, Georgia Pacific (GP) clay binder. The GP clay binder minimizes slime adsorption on quartz and hematite particles by agglomerating clay particles to reduce their surface area. It also helps depress hematite flotation due to its unique chelating action on iron ions. The results from this study show that the GP clay binder is an effective depressant in iron ore flotation. When it was used as a substitute for corn starch, it increased concentrate grade from 60.78% to 67.67% and increased iron recovery from 71.96% to 72.90%. The combined use of GP clay binder with corn starch produced even better flotation performance, increasing iron recovery to 78.15%, while the concentrate grade remained stable at 67.08%. Keywords: Georgia Pacific clay binder, Iron ore flotation, Flotation efficiency

Jan 1, 2010

By Homero Delboni, Mauricio Guimarães Bergerman

"At the regrind or secondary grinding stages of metal ores, usually the concern about the energy efficiency is extremely important. In general, the specific energy consumption at this stage is higher than in the primary stages of grinding. In addition, it has been observed a tendency of finer grinding in the new projects of metallic ores, due to the finer mineral liberation, which leads to an increasing capital and operational costs. In Brazil, during the last 10 years, regrind P80 sizes of approximately 40 to 20 ?m have been necessary in all new iron and copper plants. The use of conventional ball mills, adequate for primary grinding, can result in low energy efficiency with products below a P80 of 50 ?m. This paper presents an overview of the regrind circuits in Brazil that operate with vertical mills and the results of industrial surveys at selected vertical mill circuits. Where possible, comparison is made between the plant results and the design criteria and laboratory regrind tests used for the mill sizing."

Jan 1, 2014