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By Gordon E. Agar

Several correlations have been proposed to relate energy consumption and size reduction in comminution, and although these are arrived at from different starting points, it is postulated that they are all statements of the same basic concept. To test this postulate, the dry ball mill grindability of langbeinite was determined, and the results were analyzed according to the various methods. An examination ' of the energy-particle size relationships proposed in the recent past revealed that they had much in common. In fact, the conclusion was tentatively drawn that these expressions were essentially the same, even though they were arrived at from quite different basic premises. The equations attributed to Charles2 and Holmes3 were shown to re- duce to the same single equation, W - A K-3, and the simulated continuous test used by Maxson et al.4 was shown to give the best experimental value of the required empirical parameter, ß. Furthermore, the size distribution parameter a in the Schuhmann equation, y - (x/K)2, was shown to be equal to ß in many cases. The kinetic approach used by Arbiter and Bhrany5 should give the same results as the Maxson test procedure; however, the batch operation used by Arbiter and Bhrany could not produce data that would be as precise as the simulated continuous technique. To test the validity of these conclusions, the simulated continuous method was used to obtain data on the dry grinding of langbeinite. The results are discussed in terms of the various equations and approaches. APPARATUS AND MATERIAL A ball mill with internal dimensions of 17.5 cm (6 7/8 in.) in length by 19.4 cm (7 5/8 in.) in diam was loaded to 50% of its volume with balls 3.2 cm in

Jan 1, 1969

Jan 1, 1913

By Lawson J. Taylor, Paul N. Worsey

Recent reputable evidence conclusively indicates that conventional chemical delay elements in delay detonators are notoriously inaccurate and can thus seriously affect blasting efficiency.

Jan 1, 1983

By C. W. Price, G. A. Wheeler

BERYLLIUM has always been a difficult material to prepare for metallographic examination. Severe surface deformation occurs during mechanical grinding and polishing, and a suitable bright-field etchant has not been developed. Certain electrolytic techniques produce satisfactory polishes, but these techniques have not yielded entirely consistent results. Furthermore, they have not provided satisfactory bright-field etches. The purpose of this paper is to describe an electrolytic polishing technique that can also provide an excellent bright-field etch. In addition to the bright-field etch, other advantages of this technique are excellent reproducibility, rapidity, and ease of polishing and etching. Experimental Technique. Specimen Preparation. Beryllium specimens may be either mounted or unmounted for the use of this technique, and the size of the specimens is not important. Specimens with surface areas up to 4 sq cm have been electrolytically polished and etched successfully with this technique. The most important requirement is to provide a good electrical contact to the specimens, preferably on the back of the specimens. When specimens are mounted, a hole is drilled through the back of the mount so that the specimen can be contacted with a probe. Conventional metallographic grinding techniques are used to prepare the specimens for electrolytic polishing. The specimens are ground on silicon carbide papers. Grinding through the usual series of papers down to the 600-grit paper is recommended to minimize the electropolishing time, although successful electrolytic polishes and etches have been obtained by grinding only through the coarser papers. A continuous flow of water is used during grinding to provide lubrication and to minimize contamination. Mechanical polishing is not required because high rates of material removal are achieved with the electrolytic polishing. Polishing. Most of the results reported in this paper were obtained with a "Disa-Electropol", manufactured by Struers Scientific Instruments of Copenhagen, Denmark. Satisfactory results have also been obtained with the conventional beaker technique of electrolytic polishing, however, the conditions applicable to both the Disa unit and the beaker technique will be described. Stainless-steel cathodes are used in both techniques. In the beaker technique, a flat cathode, with an area at least twice that of the specimen, is used, and the specimen is held parallel to the cathode. The distance between the specimen and the cathode affects the quality of the electropolish. This distance is set at about 7 mm in the Disa unit; the same distance produces the best results in the beaker technique. Specimen-cathode distances greater than about 20 mm produce considerable relief, while distances less than 7 mm cause high current densities that are difficult to control. An electrolyte of 2 pct HC1, 2 pct HNO3, and 2 pct HCIOl in ethylene glycol gives the most satisfactory results for both electrolytic polishing and etching. This electrolyte was developed by altering the composition of a similar electrolyte used for electrolytic lapping1 and adding HClOl to improve the etching characteristics of the electrolyte. Variations of from 0.25 pct to as much as 5 pct of each of the acids do not significantly affect the results, but the greatest amount of control and reproducibility can be obtained with the composition of 2 pct of each acid. Generally, lesser amounts of the acids produce lower polishing and etching rates, while greater amounts of acids cause high current densities that are difficult to control.

Jan 1, 1968

Longwall minim; is a highly mechanized, high productivity mining method that is finding increasing applications in coal. Although the method would be highly advantageous in certain hard rock mining applications it cannot be applied in hard rock because no suitable cutterhead exists for such materials. The wedge longwall cutterhead is a, roller cutter device that is wedge-shaped, with cutters arranged to eliminate the very large normal force ordinarily required to cause such cutters to penetrate hard rock. However, the wedge geometry cannot be extended to a point: special nose cutters are needed to open a narrow slot for the wedge. This report describes the design, fabrication, and successful field testing of these critical nose cutters.

Jan 1, 1974

By Xuejing Xie, Tianxiang Ren

Paper presented at the 28th International Geological Congress held in Washington DC, July 1989 (International geochemical mapping sessions). Standardised stream-sediment sampling procedures have been used in mountainous and hilly terrains. Special sampling procedures were developed for application in remote environments, such as high mountains, desert, semi-desert, karst and loess-covered regions. The diversified analytical methods used in more than 20 analytical laboratories participating in the project have been unified into two multi-element, multi-method analytical systems. A unified data monitoring procedure was developed based on primary and secondary standard samples. To date the project has covered about 4 000 000 km2 and the aim is to complete the coverage within the present decade

May 1, 1991

By J. K. Richmond

Early research on coal dust explosions by the Federal Bureau of Mines and in other countries is reviewed to examine the effect of a single inhibitor, rock dust, on the explosion limits of coal dust. The parameters studied in this research included coal dust fineness, volatile content, and type of initiation. This research resulted in appropriate safety regulations in the respective countries. Also reported are the results of recent research in the Experimental Mine of the Bureau of Mines to investigate in detail the limits of coal dust explosions; the research used three types of coal with rock dust added as the independent variable. New experimental techniques and new criteria for defining propagation/nonpropagation were applied to the experiments. Also, a limit explosion propagation model is proposed based on the assumption of rapid devolatilization of the coal particles, with the subsequent combustion of the evolved volatile products contributing primarily to the propagation of the explosions. The model assumes also that the resultant char acts mainly as an inert diluent similar to the rock dust. The model also suggests that the function of stronger initiation is mostly to lift more dust from the mine surfaces.

Jan 1, 1975

Every automatic citizen is an automatic recipient of a miner's right under the present Mining Act (Chapter 195), but this alone does not entitle any automatic citizen to mine for minerals on any land, even his customary group's land. Without complying with requirements of the Mining Act, any automatic citizen who engages in mining solely on the basis of a miner's right would be mining illegally. He would also be engaged in illegal mining if he mines on customary or other non-government land. Even if mining is legally pursued by an automatic citizen, he does not acquire ownership of minerals without first making the required royalty payments to the State.

Jan 1, 1991

"A long-term mine production schedule optimization based on stochastic integer programming is presented that manages the risk due to geological variability and uncertainty while jointly considering mine profitability, truck fleet requirements and waste management. The evolution of the pit is controlled so that space within the mined-out pit is continuously provided to allow for tailings and waste rock to be replaced, thus minimizing the project’s environmental footprint. The method is applied at a taconite iron ore deposit and has a project net present value that is 16.9 percent higher than that of a conventional schedule and has a higher chance of meeting production forecasts. The stochastic schedule reduces equipment requirements by delaying waste mining and by mining selectively in order to meet plant ore feed requirements without stockpiling material, resulting in 23.7 and 26.2 percent lower mining capital and operating costs, respectively. IntroductionThe LabMag iron ore deposit is part of the Millennium Iron Range, a 210-km (130-mile) belt of taconite in northern Quebec and Labrador, Canada. LabMag has significant economic potential. It contains more than 3.3 Gt (3.6 billion st) of proven reserves at an average total iron content of 29.8 percent and is very low in impurities. However, on a project basis of 23 Mt/a (25 million stpy) of product, the required capital expenditure is estimated at more than $5 billion (SNC-Lavalin, 2014), which necessitates careful evaluation of all sources of risk. Resource estimation is one of the main sources of risk in a mining project as knowledge of the orebody is primarily based on drilling, which is often sparse because it is expensive. If the expected ore tonnages and qualities are not obtained when mining, the project cash flows are directly affected. The expected quantities and qualities of ore and waste are defined by the mine production schedule, which specifies the sequence of extraction and is dependent on the resource estimation. The goal of mine production scheduling is thus to maximize the expected profit, while also meeting all production targets and constraints, by creating an extraction schedule that is robust in the face of geological risk and has the highest chance possible of actually being realized."

Jan 10, 2017

By Robert Thomas

DURING the past 20 years the advantages of reinforced concrete as a substitute for timbering in so-called permanent mine openings have been fully recognized, and its use has become almost general practice in the larger mines. The term "permanent mine openings" is used advisedly and is assumed to embrace such openings as ventilation shafts, material shafts and main hoisting shafts, with their adjacent stations, ore pockets, etc. In the concreting of such openings, the actual cost as compared with that of timbering has been of secondary consideration, the support of large openings, elimination of fire hazards, and prevention of inter-ruptions to production being the primary objectives. The ultimate economy, however, of lining such openings with concrete when they are to remain in use during the entire life of the mine, and especially when they are in bad ground, will seldom be questioned. During this 20-year period there have appeared in engineering publi-cations a number of interesting articles on the use of concrete in mines, nearly always describing some specific project of major proportions, such as the concreting of ore pockets, large stations or main hoisting shafts. Such articles are unquestionably of interest, since the projects require considerable engineering thought, not only in the method of excavating large openings, but in their engineering design as well. Concreting of main hoisting shafts, particularly when this is done with the least possible interruption to production, provides some interesting problems. The concreting of haulage drifts of the dimensions commonly found in mines, on the other hand, soon develops into a routine operation, there-fore it is with some hesitancy that the author attempts to prepare an article on this subject. The writer can recall only one article on the concreting of mine haulageways, although several articles have been written concerning the concreting of tunnels considerably larger in dimensions than those required in general mine practice.

Jan 1, 1936

By Jack Curran

KANSAS CITY, MO - Performing one of the most impressive urban building-implosion projects in recent memory, Tulsa, Oklahoma-based Dykon Explosive Demolition Corp. and Omaha, Nebraska-based Anderson Excavating recently felled the landmark Columbia Bank Building in downtown Kansas City, Missouri, USA. Although every structural blasting project presents special challenges, this undertaking was most notable for its unusually unique structural design, tight clearances, and high risk to adjacent structures.

Jan 1, 2003

By A J. Rorke, U Chhika

"A series of tests was carried out on a dry blend of PPAN and LAN prills (LANFO). The objective of thetests was to determine detonation stability and VOD performance compared to ANFO. Heave andfragmentation results in the field were also evaluated visually. A number of factors were behind for.mulating this blend. A lower cost is combined with higher in-hole energies, but at slower reactionrates and lower peak borehole pressures. The resultant effect is improved heave characteristics andlower energy losses caused by inefficient crushing of the rock immediately around the borehole.The test results indicate that IANFO is ideally suited to blasting in softer midburden and overburdenrock types often encountered in coal strip mines."

Jan 1, 1995

By Harvey S

After considerable experience in connection with the magnetic iron-ores at the South, especially in the Cranberry district of western North Carolina and eastern Tennessee, the writer was led into a thorough investigation of the magnetic separation of iron-ores, and, from this investigation, has gradually been developed a separating machine which it is the purpose of this paper to explain. Numerous United States patents have been issued upon machines for magnetic separation. Since the original patents date back to 1849, it is not possible to-day to establish broad claims upon the principles of electro-magnets as applied in such machines. Among these inventions there are certain types of separators which have very marked practical advantages over the others; and these successful machines, while varying radically from each other in their proportions and arrangements, are all based upon a principle originally explained in a patent which was granted in 1870, and which has now expired by limitation. The problem of practically separating iron-ores, as found in the mines, is very different from the separation of a purely magnetic substance from a purely non-magnetic one, since the crystals of magnetite, scattered through the ore-bearing rock, and sometimes collected in masses, are of very different sizes. The average size of the particles may be definitely ascertained for each mine, and the crushing- and screening-machinery may be adapted thereto, but there will still be a large percentage of very fine crystals which, in the crushing for the average, will not be broken apart from the gangue. If these mixed particles are thrown into the heads they carry gangue with them, and if thrown into the tails they occasion a loss of ironore. There are two methods for preventing such loss. One is, to crush all the material to the size of the finest particles, which means, of course, a large crushing-plant, heavy wear and tear, and excessive cost for repairs, and the production of only a very fine-grained concentrate which our blast-furnace managers, to say the least, do not

Jan 1, 1893

By Liu Jie

Refractory iron ore deposits in China have various genesis and complicated types, the nature of which is poor, fine-disseminated and complex. Therefore, refractory iron ore could scarcely be separated and utilized by traditional mineral processing technology at present. It is necessary to explore deep reduction technology to change the characteristics of refractory iron ore and to use effectively the iron resource. And deep reduction technology is that on the condition of higher reduction temperature than that of magnetic roasting and stronger reducing atmosphere, the iron oxides from iron ore was reduced to metallic iron particle that is easy to dissociate. And then production from deep reduction is easily separated by magnetic separation and iron powder production was obtained finally. Deep reduction technology for Lingyang iron ore from Jilin, China, as the refractory iron ore, was studied in this paper. The influences of such main factors as reduction temperature, time and coal content were investigated. The results showed that the Metallization rate of reduction product was up to more than 90% under optimum conditions, and then higher iron grade and recovery of reduction iron powder were obtained from subsequent magnetic separation. Furthermore, the deep reduction mechanism in the system was studied by the means of XRD and SEM analysis for reduction production and Physical Chemistry of Metallurgy. Analytical results indicated that during deep reduction, the size of iron particle from deep reduction materials was increasing as reduction temperature rising and reduction time extending. The growth of metallic iron particle from deep reduction production was divided into such three stages as reduction nucleation, deep reduction and growth of metallic iron particle.

Sep 1, 2012

By K. Terhaar, K. Prisbrey

The objective was to determine operating protocols for a lead and silver column flotation cleaner, being considered for installation at Sunshine Mining & Refining Co.’s Kellogg mill in Northern Idaho. In this column, tetrahedrite and galena were floated, and pyrite and other gangue minerals, including siderite and silica, were depressed. The procedure was to develop a dynamic simulation using a linear transfer function approach. The transfer function related cause and effect variables such as the influence of collector and depressant dosages on recovery and grades. Bench-scale flotation tests followed by pilot column testing provided the data used to develop a linear transfer function. The transfer function was derived using a spreadsheet. This model was applied to simulate how the flotation column could be made to respond to disturbances in feedgrade. The results were that xanthate, zinc sulfate, and sodium cyanide were found to be suitable controls for grade and recovery. Simulations showed the best sequence of manipulations of these reagents, and these sequences were useful for future operator training. The conclusion was that linear transfer functions were able to simulate lead and silver recovery, develop scenarios for operator training, and provide a foundation for future on-line control.

Jan 1, 1999

By O. Celep, H. Deveci, Ersin Y. Yazici, F. Ahlatci

"There are increasingly stricter environmental regulations imposed for use of cyanide leaching for the extraction of gold from ores. Alternative lixiviants to cyanide, preferably with low toxicity, have been extensively studied. Thiosulphate has emerged as one of the most suitable alternative leaching agent in place of cyanide due to its low toxicity and technical attributes e.g. fast leaching kinetics, high gold extractions from carbonaceous ores in particular. High solubility of most copper minerals in cyanide solutions results in low gold extractions due to excessively high consumption of cyanide. In contrast, low reactivity of copper minerals in thiosulphate solutions makes thiosulphate leaching potentially suitable alternative for treatment Cu-bearing gold ores. The extraction of gold/silver from a copper-bearing pyritic gold concentrate (62 g/t Au, 110 g/t Ag and 0.3% Cu) in thiosulphate solutions was investigated in this study. The concentrate is composed of predominantly quartz (25%) and pyrite (32.7%) as well as sphalerite (5.37%), galena (2.12%) and anglesite (1.13%). Other minor minerals are arsenopyrite, chalcopyrite, covellite and bournonite. Previous studies by the authors indicated that the concentrate did not respond well to cyanide leaching (i.e. 45-46% Au/Ag at 1 g/L NaCN). The effects of concentration of ammonia (0.2-1.5 M NH3), thiosulphate (0.1-0.75 M S2O3) and copper (0-20 mM CuSO4) on the extraction of gold and silver over 8 h. was investigated. Increasing the concentration of thiosulphate and ammonia substantially improved the rate and extent of gold leaching while high copper levels produced an adverse effect particularly at low concentration of thiosulphate (i.e. 0.1 M). Complete extraction of gold was achieved under suitable conditions. In contrast to gold, silver extractions remained consistently at low levels (i.e. 28%). These findings demonstrated that thiosulphate leaching could be used to achieve acceptable levels of gold extraction from the copper-bearing pyritic gold concentrate."

Jan 1, 2018

By Ralph W. Barbaro

In the mineral industry, the objective of a mining venture is to extract, process, and market a mineral commodity in such a manner that the profit of the venture is maximized. In a mining venture, a company normally has control over mine production scheduling, the selection and location of processing facilities (mineral beneficiation plants, smelting plants, refineries, or blending facilities), processed ore blending, and the selection of markets. The flexibility of the above factors provides many alternatives to satisfy the needs of each market with regard to quantity and quality of ore. The purpose of this paper is to present a mathematical model for determining the alternative that yields the maximum profit. Production planning is generally concerned with the best utilization of fixed resources, more specifically, with the determination of production and inventory levels to meet fluctuating demand requirements. A mine can be any source of ore such as an entire mine, a production unit within a mine, or an independent supplier. The objective of production scheduling is to determine the times at which each mine will be used and to allocate a required level of production. Production planning and scheduling problems are intimately associated with the location of new and existing mines and processing facilities. Although the location of the mines is usually fixed, there can be considerable flexibility in locating new processing facilities, in the selection of the processing plant, and in blending the ore before and after processing.

Jan 1, 1983

By Pramila Misra, Jibardhan Meher, Debadutta Das

The concentrated coal-water slurry has been receiving considerable attention recently due its ability to replace fossil fuels. Attainment of stable and concentrated slurry has been succeeded so far through several physical and chemical techniques. The present article reports the formulation and stabilization of a highly concentrated coal-water slurry formed from five varieties of non-coking coals with variable ash contents obtained from Eastern part of India, employing three varieties of starch esters, such as starch benzoate, starch formate, and starch carbamate as dispersant. The apparent viscosity of the modified coal-water slurry has been measured by varying coal loading, dispersant percentage, pH, temperature, etc. The apparent viscosity of the slurry has been found to be decreased substantially on addition of 0.8% of adsorbate in the slurry. The particle-particle interaction has been considerably decreased and stable concentrated coal-water slurry containing high weight fraction of coal (61.5-63.5%) has been achieved in each case. The slurries stay in a non-settling form for about a month with viscosity in a permissible low range. The coal-water slurry has been found to behave as a non-Newtonian liquid. Comparison of the zeta potentials of the naked and modified coals evidences that adsorption of the dispersants at coal-water interface results in inhibition of the agglomeration of coal particles through mostly steric repulsions.

Jan 1, 2014

Financial theory often takes some time to penetrate industry and when it does it can result in a paradigm shift in valuations and mental models. The Black Scholes option valuation was first published in 1973, although the authors were only awarded a Nobel Prize in 1997. The valuation of real options has been applied to the oil and gas industry for some time, however it has only recently been more widely applied to the non-oil, mineral resource sector. The use of real option valuation (ROV) for the valuation of marginal and short mine life resource projects is a more useful valuation tool than the conventional DCF, NPV valuation tool. The application of ROV has major implications for corporate strategy. It generally favours equity over debt funding and non-hedging over hedging. A retrospective assessment of the successful development of the Lennard Shelf Operations demonstrates the concepts of implementing real options and the value destruction of limiting operational flexibility through debt and hedging activities.

Jan 1, 2003

By L. C. Bird, N. T. L. Landgren, M. W. Mikhail

"Through funds made available in 1972 by the Nova Scotia Department of Mines and Energy (DME) and the federal Department of Regional Economic Expansion, a program was initiated to recover saleable coal from mine waste dumps adjacent to the existing Acadia wash plant in Stellarton, Nova Scotia.Following evaluation of these dumps in 1972, the Acadia wash plant was modified to treat high-ash material. The first production was recorded in late 1974. By the end of 1979, a total of 738,202 t of dump material had been processed, yielding a total of 205,212 t of thermal-quality coal.The successful Stellarton operation led to considering the possibility of recovering thermal coal from other dumps. Evaluation of the Westville dumps indicated total recoverable reserves of 1,346,617 t averaging 53.8OJo ash.Parameters for plant design were defined from the washability characteristics of the dump material and the results of a bulk test. Two options were proposed; one was to use the existing plant with some modifications, the other was to build a modular mobile plant that could be used at future dump sites in the province after Westville. At the 25% ash level, the potential recovery of coal from the dump was estimated at 41% yield (by weight) or 549,679 t."

Jan 1, 1981