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By J. E. Sallee

An experimental study has been conducted on the level of arsenic contamination in samples of zinc oxide when the zinc oxide is contacted with gas mixtures containing As4O6(g). This contamination has been determined as a function of A4O6 saturation pressure, temperature, zinc oxide sample surface area, impurities, and oxygen level in the gas mixture. The results indicated a rather clean separation can be achieved between condensed zinc oxide and gaseous arsenic oxide as long as attention is given to temperature control, and the final zinc oxide surface area. For a 300°C operation temperature and an AqOg saturation pressure of 0.38 TORR (or 0.05% As406 by volume), the contamination level is expected to be approximately 100 ppm. This suggests that arsenical dusts can be treated in the HRD flame reactor process and a reasonable purity zinc oxideproduct produced. The results also show no evidence of zinc arsenite or zinc arsenate formation.

Jan 1, 1994

By D. A. Norrgran

The recent development of rare earth permanent magnets has revolutionized the field of magnetic separation. The advent of rare earth permanent magnets in the 1980's provided a magnetic energy product an order of magnitude greater than that of conventional ferrite magnets. This has allowed the design of high-intensity magnetic circuits operating energy free and surpassing the strength and effectiveness of electromagnets. New applications and design concepts focused on the mineral and metal processing industries have evolved. This technology also led to the development of various magnetic separators specifically designed for mineral processing applications. Applications which were not previously considered are now being applied to primary mineral upgrading and recycling and secondary recovery.

Jan 1, 1993

By D. U. Gustafsson

After half a million meters drilled with Wassara we are now confident that ITH hammers powered with simple water will become an established product for production drilling. Today four drill rigs in LKAB Malmberget equipped with Wassara drill about 25 000 m per month of 4 1/2" holes. In Kidd Creek, Canada, Was sara is used for production drilling in stopes with good results. The first Wassara 6" hammer has drilled a 36 meter long, completely straight horizontal cut hole for drifting in the LKAB Malmberget Mine. Main advantages are about doubled penetration rate, very good air quality and improved hole cleaning which facilitates stabilized drilling. Disadvantages are resistance to new technology and, in some cases, the increased use of water.

Jan 1, 1995

By Frank C. Smith

THE following article covers the history of a metallurgical campaign, commenced in March, 1905, at the mines of the Socorro Gold Co., in the so-called desert region of Yuma county, Arizona. The results obtained were simply a function of necessity, as will be seen from the description of the local economic conditions and the character of the ores treated. The mines and mill of the Socorro Gold Co. are located near the small village of Harrisburg, about 60 miles from Congress Junction, Arizona, which, at the time this work was undertaken, was the nearest railroad station, and from which all supplies were brought by wagon through the desert, at a cost varying from $10 to $15 per ton in addition to the railroad freights. Wood, the only available fuel, cost $7 per cord. Water for all purposes was pumped to the plant from a well in the valley about 4 miles away. Under the Arizona law, a working-shift is 8 hr. Wages were $6 per day for foremen and mill-men, $4 per day for blacksmiths and engineers, $3.50 per day for miners, and $3 per day for shovelers and trammers. The ore consisted of quartz, in which, above the 250-ft. level, the iron-minerals were largely oxidized and some free gold was visible; below that level few traces of oxidation occurred, and pyrite constituted the principal mineralizer in the quartz, together with occasional pockets of galena and a few eccentric specks of covellite. The 20-stamp mill was equipped with plates for amalgamation, and three Standard tables for concentration. The tails from the tables were elevated by a centrifugal pump to a launder, by which they were conveyed to a 60-ton cyanide-mill for further treatment. The cyanide-mill was erected at so great a distance from the stamp-mill that a separate crew of workers and a separate power-plant were necessary. No arrangement had been made for the treatment of the concen-

Jan 1, 1907

By F. H. Gibson

An investigation was made by the Federal Bureau of Mines of methods for determining phosphorus in coal, coal ash, and coke ash. Several of these methods are being considered for international standardization. As might be expected, methods and proposals from other countries for determining phosphorus differ considerably from those accepted an standard in the United States. Some of the methods differ fundamentally in principle from the American Society for Testing Materials (ASTM) standard used in the United States; others differ only in details of procedure. Because the Bureau considered that certain of the proposed methods might offer advantages in obtaining increased accuracy and precision or in decreasing the time required for making analyses, these methods were investigated, and the results compared with those obtained by the ASTM method. The methods investigated may be grouped into three types--volumetric, colorimetric, and gravimetric. All were about equally accurate and may be used alternatively. From a practical viewpoint, when only a limited number of analyses are made intermittently, the gravimetric procedure probably is the most suitable because no special apparatus or standard solutions are required. The volumetric methods are more rapid when more analyses are made. For mass production, the colorimetric methods, although requiring a suitable photometer or spectrophotometer, are more suitable because a large throughput should be feasible.

Jan 1, 1961

By Mark Colwell

This paper summarizes the results of a research project whose goal was to provide the Australian coal industry with a chain pillar design methodology readily usable by colliery staff. The project was primarily funded by the Australian Coal Association Research Program and further supported by several Australian longwall operations. The starting point or basis of the project was the Analysis of Longwall Pillar Stability (ALPS) methodology. ALPS was chosen because of its operational focus; it uses tailgate performance as the determining chain pillar design criterion rather than simply pillar stability. Furthermore, ALPS recognizes that several geotechnical and design factors, including (but not limited to) chain pillar stability, affect that performance. There are some geotechnical and mine layout differences between United States and Australian coalfields that required investigation and, therefore, calibration before the full benefits offered by the ALPS methodology could be realized in Australia. Ultimately, case history data were collected from 19 longwall mines representing approximately 60% of all Australian longwall operations. In addition, six monitoring sites incorporated an array of hydraulic stress cells to measure the change in vertical stress throughout the various phases of the longwall extraction cycle. The sites also incorporated extensometers to monitor roof and rib performance in response to the retreating longwall face. The study found strong relationships between the tailgate stability factor, the Coal Mine Roof Rating, and the installed level of primary support. The final outcome of the project is a chain pillar design methodology called Analysis of Longwall Tailgate Serviceability (ALTS). Guidelines for using ALTS are provided.

Jan 1, 1999

By Madgwick J. C

A new strain of Thiobacil/us ferrooxidans (SPK I) has been isolated which has a higher copper to iron release ratio (2.04) than the standard T ferrooxidans (CPBI) (1.12). The diminished iron oxidizing ability enables almost quantitative release of copper (93 per cent) from a chalcopyrite-rich concentrate without interference by iron reprecipitation. In a single batch leach, Bougainville copper concentrate yielded 9.3 grams/litre soluble copper from a 4 per cent w/v suspension in 100 days at 32°C.Solvent extraction recovery of soluble copper is recommended as a final step in a leaching process.

Jan 1, 1983

By N Clarke, J Hunt, A Barros, L Keeney

The Gramalote orebody is a large low-grade gold deposit situated in the San Roque municipality, 124 km north-east of Medellin in Antioquia, Colombia. It is jointly owned by AngloGold Ashanti (AGA) and B2Gold and is currently in Feasibility Study phase. In 2013 AGA requested CRCORE to undertake a preliminary study of the potential application at Gramalote of pre-concentration by screening, part of the Grade Engineering suite. 160 samples of coarse assay rejects (-3 mm) were tested and showed one of the strongest responses seen worldwide to that time, suggesting that about 70% of the gold could be recovered into 40% of the mass. This was seen as potentially markedly improving the Gramalote economics. A large-scale testing program was implemented on site to follow up these results. A total of 18 samples of 17 t each were mined along a pre-existing exploration adit. A complex test flowsheet allowed size fractions to be generated from the as-received material as well as after crushing to 53, 23 and 3 mm, all from the same head sample. The procedures were designed after carrying out a heterogeneity study to measure sampling errors. The coarser size fractions were designed to study the effect of crushing on upgrade response and predict the response on open-pit run-of-mine ore. The finer size fractions were designed to investigate means of predicting the upgrade response across the orebody. The large-scale testing closely confirmed the average upgrade response as predicted from drill core assay rejects but found that only the -53 mm crushed material accurately predicted the upgrade response of individual samples. Ore geochemistry was able to usefully distinguish samples with good and poor response. A small study on drill core suggested that, for Gramalote, fine crushed material distinguishes vein associated and disseminated values but not other factors that control actual outcomes.

Nov 10, 2020

By E. C. Harder

The situation in the United States, at the present time, regarding the supply of manganese ores and alloys of manganese is one of great seriousness and is likely to become increasingly so while the European war continues. The two principal iron-manganese alloys, ferromanganese and splegel-eisen, are indispensable in steel manufacture, being used extensively in the Bessemer and open-hearth processes. Spiegeleisen, the lower alloy, contains between 15 and 25 per cent., and ferromanganese, the higher alloy, between 60 and 80 per cent., of manganese. Besides manganese the alloys contain iron and carbon. On the market ferromanganese is usually quoted on the basis of 80 per cent. manganese, and spiegeleisen on the basis of 20 per cent. manganese. The consumption of ferromanganese has been increasing during recent years at the expense of spiegeleisen, because larger quantities of the latter must be used to accomplish the same purpose with the result that the amount of carbon introduced with it into the molten metal is frequently injuriously great. Manganese ore proper, in the form of manganese dioxide, is used extensively in many chemical industries, especially for oxidizing purposes. It is also used for the manufacture of both wet and dry electric cells and in the manufacture of paints and dyes. The manganese ore used in this country has been derived hitherto from three principal sources: Southern Russia, Southern British India and East Central Brazil. The following tables show the quantity of manganese ore imported from these countries, and (for comparison) the domestic production, during 1912, 1913 and 1914. The imported manganese ore has been used largely in the manufacture of iron-manganese alloys and in addition large quantities of the alloys themselves have been imported, chiefly from Great Britain, Germany and other European countries.

Jan 1, 1917

By D. K. Steele

The domestic primary copper industry generates in excess of 600 million t of mining and mineral-processing waste annually. Most of the waste poses negligible environmental threat, but a small fraction, because of toxic or corrosive characteristics, may be subject to regulation under Subtitle C of the Resource Conservation and Recovery Act (RCRA) or other pertinent regulations. Among the wastes generated by various copper producers are flue dusts, slags, refinery-bleed solutions, and. acid-plant wastes. The U.S. Bureau of Mines (USBM) has researched methods to mitigate the environmental threat posed by copper-processing wastes while recovering valuable metals from these materials. Acid-leach processing of flue dusts has been demonstrated feasible along with sulfide treatment of liquid refinery wastes and acid-plant-bleed and gas-cleaning solutions to precipitate dissolved metals. In, addition, the feasibility of removing copper and molybdenum from slag, as well as stabilization of precipitated sulfide wastes by vitrification, have been investigated.

Jan 1, 2010

By A E. Petts

Record iron ore prices and a renaissance of infrastructure in the Pilbara have Flinders Mines poised to move from explorer/developer to an iron ore producer. The potential of the company’s Pilbara Iron Ore Project was first highlighted by the announcement of Rio Tinto’s Caliwingina North deposit to the north and the Fortescue Metals group’s Serenity deposit in the southeast. The success of Flinders Mines’ exploration has been based on incorporating landscape studies into an existing geological framework, and using this to understand the iron-rich materials that were emplaced during the Tertiary. The development of the Delta and Eagle deposit resource models highlights this process. There are three main mineralisation styles at the project; detrital iron, channel iron and bedded iron deposits. They have textural and mineralogical similarities with comparative deposits in the region. Gaining an insight into the geological processes unique to detrital iron deposits and more distal channel iron deposits has been important to understanding the geometallurgy of the mineralisation. The model sits comfortably with other regional oregenesis models and allows a contextual framework to be developed around the timing of deposition of the Fe-rich detritus and pisolitic nodules that dominate the deposits. The exploration model also allows Flinders to explore more effectively for bedded iron mineralisation developed prior to, and since the development of the Tertiary weathering landscape.

Jul 11, 2011

By Gordon C. Petersen, Gary A. Almeraris

This paper describes the controlled blasting techniques required to mine a rock tunnel section of a main interceptor located in the Boston Metropolitan area. The 3m (10 ft) x 2.8m (9.25 ft) horseshoe shaped tunnel was driven 490m (1600 ft) by conventional drill and blast methods. The geology varied round by round and consisted of five highly faulted and jointed igneous rock types. The tunnel intersected numerous slickenslides and open mud seams which hampered both drilling and loading operations. Smooth blasting wee critical in order to keep overbreak tc a minimum in this extremely hard but blocky ground.

Jan 1, 1991

By Z. Q. Zhou

It is the first worke in design of pile foundation to determine the carring capacity of single pile, and a static loading on site is considered to be the lost derect and reliable way. All values P and settlements S induced can be plotted as a broken-line. Since soil is a kind of elasto-plastic and cohesive material, the increasing of settlements is generally greater than that of loads. Different value Pu nay be given by different tester on his P-S diagram, because of erroys in the test and complicated, characteristics of soil. The analytical method of exponential equation shown in this paper derives a specified solution. After using an exponential curve to regress values of loads P and corresponding settlements S from on-site test, coeficients A and B of exponential equation can be obtained. With this curve an ultimate carrying capacity of single pile can be determined. The resistant forces of pile shaft and pile tip can also be defined by the tangent of the calculated knee point, as it is called (tangent method). At last, an example is given to show how the ultimate carrying capacity of f 500mm bored pile is obtained with this method for a project in Kunming.

Jan 1, 2010

By Jorge Alberto Soares Tenório, Amilton Barbosa Botelho Jr, Denise Crocce Romano Espinosa, Mónica M. Jiménez Correa

Wastewater from nickel lateritic process still has valuable metals that could be recovered. Using an ion exchange to recovery these metals, the iron becomes a problem due to the fact that it precipitate at pH 2. The aim of this research was to make iron soluble by reducing Fe+3 to Fe+2. A synthetic solution was prepared with sulfate ferric. The reducing agent sodium dithionite was used and the potential was varied (initial potential: 700, 600, 500, 450 e 400 mV) using as a reference the Pourbaix diagram for iron created by HydroMedusa software. The pH was ranged between 0.5 and 2.5, the reducing agent’s concentration was 0.5 M and the reaction time ranged between 30 and 120 min at room temperature. The ferric iron and total iron concentration were verified using a spectrophotometer with 5-sulfosalicylic acid (SSA) to determine Fe(III) and ammonia to determine Fe(II) and Fe(III) in 500 and 425 nm, respectively. The results indicated that total reduction was at 400 mV in any pH between 0.5 and 2, but less than 40% in pH 2.5 at this potential value.

Mar 1, 2017

By Stephan Jefferis

It is my understanding that the Scandinavians have done some fundamental work on durability. I have seen a study published whereby the author, Helen Anderson, comments on the durability of polyurethane grouts and there was -if I am not mistaken- a reference made to another Scandinavian testing institute comparing durability of the polyurethane to cement grout under the same type of circumstances. Circumstances are important so we should actually ask the gentleman to shed some light on this particular method because apparently Scandinavia is the place where durability has been taken very seriously and has been well researched.

Feb 10, 2003

By Navid Bahrani

The grain-based model (GBM) has resolved the difficulty of matching both the directtension (sc) and unconfined-compressive (st strengths of typical brittle rock by providing a synthetic material that mimics deformable, breakable polygonal grains cemented along their adjoining sides with deformable, breakable interfaces modeled as smooth-joint contacts. In this paper, a GBM utilizing a parallel-bonded base material is calibrated to match both st and sc of Lac du Bonnet granite and then used to simulate a Brazilian test. The Brazilian strength (sB) is slightly overestimated and the failure mode includes ductile post-peak response that is not representative of what occurs in laboratory Brazilian tests. By reducing the grain tensile strength, grain failure occurs during the Brazilian test and a more realistic failure mode that includes brittle post-peak response is obtained. However, the unconfinedcompressive strength of the modified material is too low. Sensitivity analysis on the grain and grainboundary strength properties demonstrates that the grain tensile strength controls the sB/sc ratio. Because the grain strength is controlled by the parallel-bond properties and the lowest achievable st/sc ratio in a parallel-bonded material is ~0.25, it is concluded thatsc, st and sB for a typical brittle rock cannot be matched with a GBM that utilizes a parallel-bonded base material.

Jun 1, 2012

By R Piper

The Yabulu Nickel Refinery commissioned in 1974, processes lateritic ore via a modified Caron process to produce high quality nickel and cobalt products. The Greenvale orebody provided the sole source of feed to the plant until 1990 and with well-blended mineralogy, it resulted in stable and predictable plant performance, allowing the operating focus to be on reducing energy consumption and increasing ore throughput. This approach provided better economics than pursuing increased reduction efficiency. From 1990, increasing quantities of lateritic ore were imported from Indonesia, Philippines and New Caledonia. This introduced considerable variation in ore blends and instability in plant operation but also provided the opportunity to treat higher grade ore blends which yielded higher reduction efficiencies. Ore reduction is conducted using 12 Herreshoff multiple hearth reduction furnaces, using heavy fuel oil as reductant. The æROASTERÆ Project was approved in November 2000 with the primary objective of improving Nickel reduction efficiency by: Stabilising Roaster Operation via a structured program including focused maintenance efforts, capital equipment upgrades, new process measurements, process re-design and improvements to operating skills and process troubleshooting. A structured technical program including laboratory and plant studies using one plant furnace as a pilot unit to develop improved knowledge of how the reduction process proceeds in the Herreshoff furnace. Armed with this knowledge, optimised process conditions and a reduction process model were developed contributing to a significant demonstrated reduction efficiency improvement. Technical input to the project was provided by QNI with Hatch providing the engineering and project management for the $8.5 M capital work. Execution of the work included extensive consultation with the plant operators and close cooperation between the Hatch project team and QNI operations personnel ensuring installations were completed with minimal production disruption. A strong focus on safety management resulted in a number of brownfields project relevant safety initiatives being implemented resulting in project completion without a serious injury.

Jan 1, 2002

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.  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 R. Carter, C. S. Samis

"SummaryThe results of this investigation indicate that the gold in the cyanide tailing of refractory gold cyanides is occluded in fused •particles formed during roasting. This conclusion was reached following microscopic examination of calcines produced at various furnace temperatures with different atmospheres, and a •comparison with calcines produced by decomposing samples of completely sulphated concentrate under conditions such that the maximum particle temperature varied between 6•50°C. and 1,100°C. This comparison showed that the particle temperature during a normal roast may be several hundred degrees higher than the furnace atmosphere, or that the fusion is associated with a low melting (950°C.) eutectic mixture of FeO and FeS.Because of the unavoidable particle fusion during a furnace roast, and because low particle temperatures are essential for gold extraction by cyanidation, aqueous medium oxidation under high oxygen pressures was studied. Gold recovery from calcines produced by this means was over 98 •per cent •compared with a maximum of 80 per cent from furnace calcines.IntroductionMANY arsenical gold ores are called 'refractory' because much ' of the gold cannot be satisfactorily extracted by cyaniding the raw ore or concentrate. Even when such ores are roasted to oxidize .the iron and arsenic and 'release' the gold, often 10 to 25 per cent of the gold present is lost in the cyanide residues."

Jan 1, 1952

By M Nehring, M Kizil, P Knights, A Mousavi, F Sotoudeh

A cut-off grade is used to distinguish an economically viable block of ore from non-economical ones in mining operations. In order to obtain a high Net Present Value (NPV), a strategic and precise determination of cut-off grades (mill feed/marginal, marginal/waste) is required. In recent years, the significant depletion of feed grades and increasing mining operating costs have affected the viability of new and existing mining operations. Hence, the introduction of a pre-concentration system to process ore before sending it the main processing plant has gained increasing attention for its potential improvements in resource exploitation processes, mineral processing, energy consumption and environmental impacts. The primary potential advantage of implementing a pre-concentration system is the improvement of resource utilisation and increased reserves as a result of a reduction in cut-off grade. The objective of this paper is to present a new cut-off grade method, which can be used in the presence of a pre-concentration system for underground metalliferous mining operations. The results of this study illustrate the potential economic benefits of using a pre-concertation system prior to a mineral processing operation as a result of the reduced cut-off grade and increased NPV.

Nov 10, 2020