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By AUDLEY H. STOW

I. INTRODUCTION. THE general drift of the discussion as to the relative merits of pressure- and exhaust-fans has resulted, if we may judge from the prevailing practice, largely in favor of the latter. The subject has been hitherto treated, however, with special reference to highly gaseous mines, the effect of the form of ventilation upon dust-explosions having been too little considered. Even in mines containing practically no gas, dust-explosions may occur; and if, as I believe, pressure-fans are to be preferred for their effect upon dust, it may be worth while to reopen the debate, and to challenge the advisability of exhaust-ventilation under certain conditions. There are several forms of colliery-ventilation, which may be described as follows: Plain or simple pressure-ventilation, in which the fan acts as a pressure-fan, and the movement of coal is unobstructed at the surface by doors or equivalent devices in drifts or shafts, the traveling and haulage thus being in the return-current. Plain exhaust-ventilation, in which the fan acts as an exhaust-fan, the movement of coal being likewise unobstructed at the surface, and the traveling and haulage being in the intake. Obstructed pressure-ventilation, in which the movement of coal is obstructed at the surface, in order that the traveling and haulage may be in the intake. Obstructed exhaust-ventilation, in which the movement of coal is obstructed at the surface, in order that the traveling and haulage may be in the return. The apparent advantages in running a fan "pressure" during working-hours, and " exhaust" between shifts, seem to justify the recognition of this combination as a standard form of ven-

Feb 1, 1909

By John Durkin

Electromagnetic narrow-band signals were transmitted through the earth at 27 coal mines located throughout the United States. From those Bureau of Mines tests, apparent earth conductivity values were derived based upon a homogeneous half-space model of the earth. The derived conductivity values were found to be inversely proportional to the transmitted frequency and mine depth. A linear regression model relating the logarithm of the conductivity to the mine depth was formulated, and the results indicate that the mine depth can be an adequate predictor of the apparent earth conductivity above coal mines. Apparent earth conductivity was found to decrease with mine depth.

Jan 1, 1984

By T. J. Otto, G. C. Lindeque

Productivity is improved by increasing the ratio of output to input. In an operating open-pit mine, improving the productivity of heavy mining equipment (HME) enables the unit cost of production to be reduced. To optimize HME productivity, the Kolomela open-pit iron ore mine transitioned to an enhanced short-term mine planning (STMP) process that supports the application of a manufacturing-type operating model. At the core of the enhanced STMP process is a focus on integration across the open-pit mining value chain. The interdependencies between mining activities are highlighted and emphasized, thus ensuring that mining activities are synchronized. The improvements related to HME productivity were monitored from 2019 to 2020. The utilization of mining area in the Leeuwfontein pit improved from 71% to 90%, and the blasting frequency reduced by 14% while the average blast size increased by 17%. The distance travelled during shovel relocations between mining phases reduced by 16%, and the lost time associated with drills relocating reduced by 53%. These productivity improvements resulted in an 11% increase in the loading rate of the main waste shovel at Kolomela from 0.9 Mt/month in 2019 to 1.0 Mt/month in 2020. The enhanced STMP process can be adapted to other open-pit mining operations.

Nov 1, 2021

By M Bloss, B Roberts

BHP Billiton Olympic Dam required a well-tested software product suitable for strategic optimisation and scheduling of options for a potential underground mining project. The company has a standard software package called Blasor® that is used for open pit optimisation of complex deposits such as iron ore, copper-gold-uranium and silver-lead-zinc. It applies a mixed integer programming formulation (MIP) to produce conceptual pushback designs and an optimised pushback sequence. Schedules can then be run on the resulting mine designs. Existing pushback designs can also be imported into the model and an optimum schedule generated. One of the key advantages of Blasor is that multiple strategic mine schedules can be quickly generated according to the various scenarios, options and constraints that are being investigated.It was realised that Blasor, if carefully configured, could be adapted for use in underground planning. The concept of using Blasor as an optimiser for underground strategic scenarios is to represent the underground stope and development data in the form and structure of an open pit mine. In simple terms, underground stoping areas are modelled in the form of pushbacks (phases) with vertical walls. The phase dependency tools in Blasor are used to link mine blocks and their access development drives. These underground phases are imported into the optimiser. Artificial block models are constructed using stope design tonnage and grade data at various fixed cut-offs. A variable cut-off grade model has also been developed using a method of parcels to represent each cut-off grade increment.So far, this approach has been successfully used to investigate the optimum stope design cut-off for various strategic options, the economic potential of a series of mining and processing configurations and to provide guidance on the optimum sequence for developing and mining the various stoping blocks in the resource. Examination of the results has highlighted the most suitable development paths for more detailed study.CITATION:Roberts, B and Bloss, M, 2014. Adaptation of an open pit optimiser for underground strategic planning, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 249–256 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

The paper considers Aboriginal responses to large-scale mining, including Indigenous attitudes towards land access for exploration and project development. The core question, in which I have been interested for some time (Trigger 1997a; 2000; 2001), is: what are the significant factors affecting responses among Indigenous communities to mining exploration and development project proposals?

Jan 1, 2002

By Hillary W. St. Clair

The effective coefficient for rate of reduction of a sample of granular iron ore may be determined by passing the reducing gas through a bed of the are at constant flow rate and periodically analyzing the effluent gas, The method of analyzing the data is based on a mathematical model that takes into account the variation in composition of the gas and solids with time and position in the bed. A method is described for determining the value of the rate coefficient that gives best agreement between the observed and calculated analyses of the effluent gas.

Jan 1, 1967

By W. H. Zieman

"THIS IS THE THIRD of the consecutive Annual Forums on Grinding that were instituted by Mr. L. E. Djingheuzian in 1957. The first was on the subject of Ball Milling (Transactions, Volume LX, 1957) and the second on The N on-Cataracting Ball Mill (Trans-actions, Volume LXI, 1958). From the discussions at these forums it was evident that one of the most important factors affecting the efficiency of grinding is the shape of the liners. In order to make a study of liners in use, it was •decided to seek the co-operation of operators across the country by sending out questionnaires requesting basic information. Additionally, these operators were urged to set down briefly any pertinent information on the subject acquired through experience and experiments at their own particular plants. A compilation and analysis of these data were to form a basis for discussion at the Forum on Liners at the Annual Meeting in Montreal, April, 1959. The response of the milling fraternity to this solicitation was most gratifying, and clearly indicated the importance attached by the operators to the effect of liner design upon overall grinding performance."

Jan 1, 1959

By C. H. Jr. Herty

IRON oxide .(Fe0) plays an extremely important part in the manufacture of steel. In the open-hearth furnace and the Bessemer converter it is the chemically predominant compound and controls to a large extent both the operation of the furnaces and the composition and quality of their products. Almost all of the refining action is carried out through the medium of FeO, which oxidizes carbon, manganese, silicon, and phosphorus. At the end of any open-hearth or Bessemer heat the steel contains dissolved iron oxide, which must be wholly or partly eliminated. The type of deoxidation product depends on the amount of dissolved iron oxide and on the deoxidizer used. After the heat has been deoxidized and while it is being teemed, iron oxide diffuses from the ladle slag into the metal, causing losses of deoxidizer and increase in iron oxide content of the steel. It is generally believed that non-metallic inclusions are responsible for a great many failures of steel in service and for decreased yield of steel during rolling. The basis of most non-metallic inclusions is dissolved iron oxide. This investigation was undertaken in order to determine the amount of iron oxide that will dissolve in iron under various conditions. Steel-making slags are complex and it has been thought best to determine solubility under simple slags as a first step. The study is being continued under slags whose compositions approach those of operating. slags.

Jan 1, 1928

By Melvin H. Miles

"Considerable research has been conducted on the anodic oxidation of methanol in fuel cells. The electrochemical reduction of carbon dioxide in aqueous solutions to form methanol is the same reaction in reverse, i.e. CO2 + 6 H+ + 6 e- ? CH3OH + H2O. The same catalysts and conditions may operate for both reaction directions. This carbon dioxide reduction reaction, however, must be able to compete with the electrochemical reduction of water to form hydrogen gas. Thermodynamically, the reduction of CO2 to form CH3OH is slightly more favorable than the reduction of water. The use of nearly neutral electrolytes rather than acidic electrolytes makes the reduction of CO2 kinetically more favorable. The thermodynamics of various reaction steps are presented. Similarities exist with the electrochemical reduction of CO2 and the green-plant photosynthesis process that converts CO2 to carbohydrates.IntroductionVirtually all of the oxygen in the earth’s atmosphere is of biological origin having been generated by green-plant photosynthesis from water and carbon dioxide [1]. The net reaction can be represented byCO2 + H2O ? O2 + [CH2O] (carbohydrates, etc.) (1)Chlorophyll and enzymes promote this reaction, and the energy required comes from sunlight. The actual photosynthesis process is a complex multistage reaction and requires 469 kJ mol-1 of energy supplied by the sun. Isotope tracer experiments using 18O have shown that both the oxygen atoms in the O2 molecule originate from H2O, whereas oxygen atoms in the carbohydrates come from CO2 [1]. The total amount of water on the earth is split by photosynthesis and reconstituted by respiration and combustion once every 2 million years or so. The photosynthetically generated oxygen gas temporarily enters the atmosphere and is recycled about once every 2000 years [1]. The carbon dioxide is partly recycled in the atmosphere and oceans after an average residence time of 300 years and is partly fixed by precipitation of CaCO3 and other carbonate minerals [1]."

Jan 1, 2008

By Louis C. Brichta

The Rush Creek district of Marion County, Ark., has had a more or less continuous record of zinc production over the past 40 years. The ore has come from many small mines working on oxidized and semi-oxidized deposits found in the Everton formation where that formation forms the present surface rock. Prospecting has been restricted to the hillsides above the creek levels, the actual ore outcrops being the guides. Little attention has been paid the possible sulfide zones. In August 1942, the United States Geological Survey and the Bureau of Mines recommended exploration of the Powell and Cotter formations, which underlie the Everton, for which purpose the Survey had previously located 18 proposed drill-hole sites in geological structures that seemed favorable to are deposition.

Jan 1, 1949

"Classification is an important aspect of mineral processing plants and if not operated efficiently can compromise both the throughput and recovery of the circuit. This paper discusses the benefits that can be obtained by operating the classification section efficiently. Since classification in most of the mineral processing plants is carried out using either hydrocyclones or screens the case studies involving the two classifiers were used in the discussion. Studies where optimising the classification circuit lead to improvements in the performance of the overall plant were included to show the benefits of paying attention to this area that is usually neglected. The data from the mill-float mill float, SABC, and Single Stage SAG mill circuit case studies have shown that the circuit throughput can be increased throughputs without compromising recoveries by optimising the classification circuit. On plants where the ore can be liberated at coarser sizes the experimental results have shown that replacing hydrocyclones with high frequency screens can lead to improved plant throughput with no detrimental effect on recovery. The discussion has included information on design and operational considerations for plants that have or intend to use hydrocyclones or screens that could make the classification circuit more efficient.INTRODUCTIONComminution is the process in which particles are reduced in size mainly by crushing and grinding. In most mineral processing circuits comminution is carried out to liberate the valuable minerals prior to subjecting the ore to a recovery process were values are concentrated or extracted (Mainza, Evertsson, Benzer, Tavares, Powell, Rule, Plint, …, 2013). Comminution is an energy intensive process and is usually achieved in stages. It is common to have a classifier after each comminution stage. The process is carried out in stages to minimize energy usage and to improve the efficiency of the process in meeting product specifications. Although comminution circuits have been advancing classification has remained a key component of the comminution circuit design (Mainza et al., 2013). Mainza et al. (2013) summarised the role of classification in mineral processing circuit as: to allow material in the equipment that can promote high operational efficiency, to improve material handling in the circuit, to minimize overgrinding of material to reduce energy consumption, and to provide the best quality product to enter the next stage of processing. Classification stages are employed in comminution circuits to ensure that high throughputs are processed without compromising the product quality or to produce a fine product at relatively low energy. If neglected classification can have detrimental effects on plant performance."

Jan 1, 2016

By James W. Townsend

The Vicksburg mining property lies in the southeastern foothills of the Star mining district, Beaver County, Utah (fig. 1). Within a few miles of the Vicksburg mine, lying in a semicircle from south to northwest, are such past producers of lead-silver ores as the Moscow, Hoosier Boy, Red Warrior, Wild. Bill, Harrington-Hickory, and many others. Farther to the north, in the San Francisco district, are the famous Horn Silver and Cactus mines. The formation at the Vicksburg property consists of interbedded limestone, shale, and dolomitic limestone. These beds have been metamorphosed by the intrusion of irregular masses of porphyritic igneous rocks grading from quartz-monzonite to granodiorite. Ore deposition is in north-trending fissures of sheeted zones, contact metamorphic in type. These depositions were subsequently altered to gossan. A preliminary investigation of the Vicksburg property involving surveying, mapping, and sampling was made by W. A. Young and F. H. Gunnell, engineers of the Bureau of Mines, in the fall of 1946. As a result of the investigation, a project was set up to investigate the possibility of ore occurrence at greater depth on the fissures under the mineralized zone by diamond drilling.

Jan 1, 1950

By A. CHESTER BEATTY

SO much has been written about African, and particularly about Northern Rhodesian, copper during the past two years that I feel safe in assuming that you are familiar with the general background of the Rhodesian picture. Therefore, I will confine myself to certain of the high lights in connection with the history, geology, development, ore reserves, and contemplated mining methods in this relatively new and highly important copper field., Unlike most of the other great orebodies of the world, the Roan Antelope mine was not discovered by the hoof of a starving prospector's faithful burro; nor even, as its name might suggest, by a well-placed kick of protest from an antelope stumbling over a malachite outcrop. Late in 1905 an English prospector named Collier, traveling in the N'Dola district, came upon some natives using a green powder for medicinal purposes. Closer examination of the powder revealed that it ' was ground-up malachite. Collier endeavored to persuade the natives to tell him where they obtained this medicine, but' for a long time without success, because of the general feeling among the natives that they did not wish to reveal the resources of their land to the white. Finally however, - he persuaded- brie 'of-the elders to at" least take 'him part way toward, the- place where the malachite was supposed to occur. The bid took him, to a point on the lower regions of the Luanshya river and there left him with the instructions that if he followed the stream up toward its.

Jan 1, 1931

By Lumley G. I, Duffy W. J

The risk involved with incorporating new/unfamiliar technology into mines has, in the past, largely been evaluated by the supplier of the technology. The implications on safety and productivity has been accepted as part of the process of `getting up and running'.This has changed. As companies see the lost productivity and accidents actually costing significant dollars, risk assessment is becoming an important part of the implementation of new equipment. Regulatory authorities are also seeing the preventable incidents and in some cases are now requiring a risk assessment to be undertaken on new equipment at a Mine.

Jan 1, 1992

Laboratory testwork was carried out on an overall orebody composite, of 2.9 per cent Cu and 4.2 per cent Zn, prepared from drill core taken from the Currawong fine-grained, copper-zinc massive sulphide deposit near Benambra in Victoria. While 90 per cent of the copper was readily recovered in a concentrate of 20 per cent Cu, after grinding to 95 per cent passing 38 microns, zinc responded poorly to conventional flowsheet/reagent regimes. Experience elsewhere with the use of reverse cleaning, to separate pyrite from sphalerite, led to a series of tests in which better (but still modest)metallurgical results were obtained. The best result was a zinc recovery of 55 per cent in a concentrate of 50.5 per cent Zn. The major loss of zinc occurred in the reverse cleaning stage where the unit recovery of zinc was similar to pilot plant results achieved at Mount Isa Mines on similar feedstock. Diagnostic mineralogy suggested that an overall zinc recovery of 70 per cent was probably the practical upper limit, at a 50 per cent Zn grade.

Jan 1, 1999

By J. Cooper, M. W. Staub

Environmental management systems (EMSs) have been in use for more than a decade. US mining companies are only just beginning to adopt EMSs. This lag is primarily due to lack of market forces and lack of evidence that EMSs add value over standard compliance programs. Several recent studies concluded EMSs improve environmental performance and reduce costs. State and federal regulatory agencies are using EMSs as an innovative tool to streamline the regulatory process and achieve continual environmental improvements. The climate is right for the mining industry to adopt an EMS model that improves environmental performance and takes advantage of new regulatory programs.

Jan 1, 2004

British Coal has always been a big mining company and its management has been beset with many of the problems one would associate with such an undertaking. These include its accountability to Government, its market vulnerability to competing fuels and to imported coal and its relationship with its workforce but also with its own history and size. As a fragmented private industry up to and including the Second World War, it was starved of capital and its management developed an historic relationship with its workforce which was often counter productive to success. Once nationalised, it contributed greatly to post-war industrial regeneration, investment was forthcoming to reconstruct existing mines, sink new ones and to mechanise production operations. British manufacturing companies contributed to this mechanisation drive, the very success of which drove up production and productivity and against a declining market, contributed to the reduction in size of the industry. Production machinery design evolved in the 1960s with close collaboration between manufacturers and users such that an inevitable proliferation of machinery types and specifications developed to meet local needs. Longwall mining internationally outside Western Europe only became significant in the 1970s. It became apparent that international operators demanded higher levels of plant performance from British manufacturers than British Coal did. This was the birth of the "heavy duty" plant concept. As international performances outstripped our own then British Coal moved in to invest in itself, in this heavy duty. This re-investment commenced in the mid 1970s but only gained real momentum in the 1980s when it became a virtual re-equipping exercise for the whole industry.

Jan 1, 1988

By F. A. V. Guimarães, A. M. Costa

"The moisture in sintering is a very important parameter for the performance of the process. It allows that the granulation takes pace in an efficient way making the water bridges between the bigger particles used as nucleus and the finer particles that perform the coating of those coarse particles. The formation of the micro pellets is extremely important to prevent loss in permeability of the bed in the sintering grate, avoiding excessive fuel consumption and producing a quality sinter. The aim of this project is to use some of the methodologies for determine the saturation degree on ores and coal to determine the optimal moisture for sintering. In the sinter pot grate series, 3 to 4 assays in a series of 10 are required to determine the optimal moisture for the process. The saturation degree curve test has shown that is really viable to use this technique to skip those tests and go directly to the series to determine productivity and the coke / anthracite consumption. In an industrial scale can be used to adjust the water addition in the conventional mixing methods used in the sintering plants to increase productivity in the process.INTRODUCTION Sintering Sintering is a high temperature agglomeration process in which iron ore fines are partially melted and bonded together using fluxes and a source of fuel, usually coke breeze. The agglomerated product, sinter, has improved metallurgical properties making it an ideal ferrous burden that enable the passage of hot gases in the iron-making blast furnace. The sintering process is normally carried out over three basic stages: granulation, ignition/sintering, and product sizing. In the granulation stage, iron ore fines (usually a blend of selected ores), sinter return fines, fluxes and fuel, and are mixed with water and micro-pelletised in a drum or disc before being introduced in the main granulation circuit. (Wang, Teng, & Wang, 2017)."

Jan 1, 2018

By James P. Bennen

Limited efforts have been made to recycle/reuse-spent refractory materials in the steel and aluminum industries of North America. The driving force is usually part of a larger waste reduction program. -Economic or legislative forces have not been a driving force for spent refractory recycling/reuse. Past and current spent refractory recycling / reuse practices will be reviewed, with emphasis on specific programs at steel and aluminum companies. Program goals and progress of the joint Office of Industrial Technologies-DOE/Steel Manufacturers Association program directed at spent refractory reuse with electric arc furnace steel producers will also be discussed.

Jan 1, 2000

By P. C. Good

Work was done to determine conditions necessary for efficient electrodeposition of aluminum from fused chloride electrolytes. Aluminum was deposited from a molten chloride salt electrolyte over a temperature range of 150° to 750° C. At lower temperatures in a heat-resistant glass cell, aluminum was deposited on stainless steel and on aluminum cathodes. The deposit was recovered in the form of light, feathery dendrites that could not be consolidated. At 750° C, molten aluminum was deposited at cathode current efficiencies as high as 90 to 100 percent on titanium diboride cathodes and in molten aluminum cathodes. Nitride-bonded silicon carbide was the best cell material, although porcelain was also used. The electrolyte consisted of a mixture of sodium and potassium chlorides in 1 to 1 mole ratio, containing aluminum chloride in concentrations ranging from 2 to 30 weight-percent in cells holding up to 1,000 grams of electrolyte. Generally favorable results were attained in studies made at temperatures greater than the melting point of aluminum.

Jan 1, 1966