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By Herbert Clark Hoover, Lou Henry Hoover

PREVIOUSLY I have dealt with the methods of separating silver from copper. There now remains the portion which treats of solidified juices ; and whereas they might be considered as alien to things metallic, nevertheless, the reasons why they should not be separated from it I have explained in the second book. Solidified juices are either prepared from waters in which nature or art has infused them, or they are produced from the liquid juices themselves, or from stony minerals. Sagacious people, at first observing the waters of some lakes to be naturally full of juices which thickened on being dried up by the heat of the sun and thus became solidified juices, drew such waters into other places, or diverted them into low-lying places adjoining hills, so that the heat of the sun should likewise cause them to condense. Subsequently, because they observed that in this wise the solidified juices could be made only in summer, and then not in all countries, but only in hot and temperate regions in which it seldom rains in summer, they boiled them in vessels over a fire until they began to thicken. In this manner, at all times of the year, in all regions, even the coldest, solidified juices could be obtained from solutions of such juices, whether made by nature or by art. Afterward, when they saw juices drip from some roasted stones, they cooked these in pots in order to obtain solidified juices in this wise also. It is worth the trouble to learn the pro- portions and the methods by which these are made. I will therefore began with salt, which is made from water either salty by nature, or by the labour of man, or else from a solution of salt, or from lye, likewise salty. Water which is salty by nature, is condensed and converted into salt in salt-pits by the heat of the sun, or else by the heat of a fire in pans or pts or trenches. That which is made salty by art, is also condensed by fire and changed into salt. There should be as many salt-pits dug as the circumstance of the place permits, but there should not be more made than can be used, although we ought to make as much salt as we can sell. The depth of salt-pits should be moderate, and the bottom should be level, so that all the water is evaporated from the salt by the heat of the sun. The salt-pits should first be encrusted with salt, so that they may not suck up the water. The method of pouring or leading sea-water into salt-pits is very old, and is still in use in many places. The method is not less old, but less common, to pour well-water into salt-pits, as was done in Babylon, for which Pliny is the authority, and in Cappadocia, where they used not only well-water, but also spring-water. In all hot countries salt-water and lake-water are conducted, poured or carried into salt-pits, and, being dried by the heat of the sun, are converted into

Jan 1, 1950

By S. Homulos

"Introductory and GeneralTHE Northwest Territories comprise all that region -of Canada lying between Yukon Territory and Hudson bay and north of the 60th parallel of latitude. For purposes of mine .administration the Territories are divided into three districts: Yellowknife, McKenzie, and Arctic and Hudson Bay. Mining recording offices for the respective districts are maintained at Yellowknife, Fort Smith, and Ottawa. The mine inspection for the entire area, and also for Yukon Territory, comes under the Federal Department of Resources and Development. Two mining inspectors are responsible for these inspections: the Chief Inspector of Mines, with headquarters in Ottawa, who makes trips into the north at least twice a year, and a Resident Inspector, stationed in Yellowknife.The Resident Inspector is constantly making inspections of active properties. This involves a considerable amount of air travel as the region is large and properties are widely scattered.Although there has been prospecting and staking of claims in each of the three districts of the Northwest Territories, actual mining has been conducted only in the Yellowknife district, and for purposes of this paper we are solely concerned with that district."

Jan 1, 1952

By Askari-Nasab, D. Checkel, K. Awuah-Offei

Life Cycle Assessment (LCA) is an emerging environmental management tool for examining environmental impacts from cradle to grave. In this paper, LCA is used to evaluate the acidification potential (AP) and global warming potential (GWP) of belt conveyors and truck haulage systems in a surface gold mine using the ISO 14040 standards. The results show that, for AP, the truck system has 32 kg of equivalent SO2 per functional unit, compared to 8 kg for the conveyor system. However, for GWP, the conveyor has 2,820 kg of equivalent CO2 per functional unit, compared to 648 kg for the truck option.

Jan 1, 2009

By Alex Doll, Derek Barratt

"There is a number of comminution tests commonly used in the mining industry. Many of the tests are used for a particular grinding model or mill sizing program and are incompatible with other tests of different models. This paper provides an overview of the commonly used grinding and crushing tests, which models (or practitioners) use a particular combination of tests and draws some relationships between the incompatible tests based on the DJB Consultants Inc. database of projects.Case studies will demonstrate similarities and differences between major mining districts with some comments about homogeneous and heterogeneous behaviour within the grindability results.INTRODUCTIONThere are a number of bench-scale grindability tests in use for sizing and predicting throughput for grinding circuits. Part of the reason for this variety is there are a number of different grinding models in use in the Industry, and those models operate using incompatible test results as input (Doll and Barratt, 2008).By using the database of testwork in the DJB Consultants, Inc. (DJB) Millpower 2000 database (see Table 1), some of the more commonly used tests are compared and relationships will be drawn."

Jan 1, 2011

By R. L. Wolfrom, R. Hogg, S. Chander

A gravimetric method for measuring rates of capillary rise in powders was explored. Methods to improve reproducibility and consistency of the results were investigated. In particular, the effects of particle size and packing uniformity were addressed. Studies of the wetting behavior of both spherical glass beads and irregularly shaped synthetic graphite particles by various organic liquids were carried out. Standardized procedures for bed preparation are described. The applicability of the Washburn equation for surface energy evaluation in such systems is discussed.

Jan 1, 2002

Brief descriptions of several types of unit pulverizeI' are given and the functioning of the components that crush, carry, dry and classify the coal is considered. A distinction is drawn between pulverizers which crush particle beds and those .operating by free-crushing. The overall performance of pulverijlers is considered in terms of correlations between mill variables, coal grindability, abrasiveness, moisture and particle size. Brief discussioiJ. of the influence of pulverized fuel quality on boiler operation and of pulverizing costs concludes the paper.INTRODUCTIONModern coal pulverizers function as carriers of materials and as crushers, as dryers and as size classification machines and, thus, the unit pulverizer comprises. several components that normally function as separate apparatus. The controls of the unit pulverizer must have sufficient flexibility to accommodate rapid variations of boiler load or coal quality. Further, the machine must be robust, yet easy to maintain preferably at annual intervals-so that maintenance costs are small (for coal is a relatively cheap material). Usually, the full load of a modern pulverized-fuel fired boiler can be raised with one pulverizer off-line. All coals, from anthracites to brown coal, may be prepared as pulverized fuel (hereafter P.F.) .Each pulverizer of a direct-fired boiler has, broadly, to supply the burners with coal powdered so that about 80 per cent passes a 200 B.S. sieve and only a small proportion, less than about 10 per cent, remains on the 100 B.S. sieve. The classification processes must prevent any appreciable proportion of coarse particles in the P.F. and yet not return excessive proportions of "finished" fines. The quality of the P.F. should not vary greatly with output rates which may be anywhere between the maximum rate and one quarter ofthe maximum. The suspension of P.F. in the primary air...

Jan 1, 1957

By Edmar de Souza Silva, Antonio Augusto Gorni, Emanuelle Garcia Reis, Daniel Bojikian Matsubara

Controlled rolling followed by accelerated cooling, known worldwide as TMCP, aims to increase mechanical properties without toughness deterioration. The process principle is to promote the plate cooling with water jets along the range of the austenite transformation temperatures. The accelerated cooling process is only fully effective when controlled in an integrated manner, as it alone cannot ensure significant improvements in the final properties of steels. Plate surface quality depends on some parameters that must be controlled before the start of the plate accelerated cooling. Good flatness is essential to avoid irregular water accumulations during cooling. After the reheating process, the slab should have uniform temperature, uniform austenitic grain size and easily removable scale. The slab thermal and microstructural heterogeneities are inherited by the rolled plate and tend to increase further during the accelerated cooling. This results in flatness problems, high level of internal stresses and mechanical property variations. The descaling strategy is an extremely important factor and must be determined with great caution. It is important that scale thickness and distribution is uniform to ensure homogeneous cooling over the entire plate surface. Otherwise, there will be an uneven temperature distribution, which can cause serious problems of flatness, surface quality and mechanical properties.

Oct 1, 2019

By S. I. Anufrieva, N. A. Permyakova, E. G. Likhnikeevich

"Russia’s rare metal reserves are composed of compositionally and structurally complex ores and are characterized by an increased content of natural radionuclides due to their geochemical similarity with rare metals. For instance, concentrates of Zashikhinsky daeposit are characterized by an increased content of uranium (0,06%) and thorium (0,59%); Beloziminsky deposit holds pyrochlore-apatite-magnetite-carbonate ores characterized by increased radioactivity (130 mkR/h) and containing 0,0016-0,0025% of uranium; Etykinsky deposit is characterized by columbite-pyrochlore-microlith mineralization with an average ore grade of 0,013% of uranium and 0,0020% of thorium; eudialyte concentrate of Lovozero deposit (Alluaiv area) belongs to Class II of mineral reserves. Industrial development of these mineral reserves involves the need to comply with environmental standards, public health requirements applicable to finished core and by-products, to take into account the amount and class of the generated radioactive waste, the possibility of disposal or recycling of the radioactive production waste. Concentration processes of radioactive rare metal feeds most often lead to a concentration of natural radionuclides and their accumulation in concentrates. Comprehensive hydrometallurgical processes are currently under development for such concentrates, aimed at producing salable products compliant with the radiation safety standards. The choice of the hydrometallurgical processing method for radioactive rare metal concentrates is based on the mineralogical component of the concentrate, textural and structural features, the distribution of valuable components and impurities, and the content of radionuclides. A systemic approach to the selection of processing methods, in particular integrating several methods, is an effective solution. Methods may not only be combined, but also inextricably linked with each other. Hydrometallurgical processing methods include leaching by acidic and alkaline agents; sulfatization for selectively decomposing the minerals and moving the bulk of U and Th into solution; fluorine extraction process. Methods of precipitation and co-precipitation, extraction (by liquid and solid extractants), sorption, and ion exchange are used to decontaminate the solutions by removing thorium, mezathorium, uranium, and their radioactive decay products. Agents used in hydrometallurgical processing of radioactive rare metal ores include sulfuric, nitric, hydrochloric, hydrofluoric acid, alkali (NaOH, KOH), sorbents (for example, AB-17) for sorption of uranium and extractants (mono- and bidentate organophosphorus compounds, diamides, etc.) for the extraction separation of rare, rare-earth, and radioactive elements."

Jan 1, 2018

By Bernard Porter

The rate of the heterogeneous reaction between reactor-grade yttrium and lithium fluoride in lithium fluoride-yttrium fluoride mixtures was measured using a quartz spring balance. At 950° C the magnitude of the rate of reaction is 10-5 grams of yttrium/cm2-sec. The heat of activation for the reaction is 38.3 kilocalories per mole of LiF. A surface-controlled mechanism is proposed in which LiF is adsorbed on the yttrium metal surface. An activated complex is formed when additional LiF reacts with the adsorbed LiF-metal site. The activated complex then decomposes to the products) which are lithium metal and YF3. The importance of the reaction in the electrowinning of yttrium metal from fluoride electrolytes is discussed.

Jan 1, 1967

By C. L. Schneider

The problem of predicting the liberation spectra produced by a closed continuous grinding circuit is of fundamental importance for the design, optimization and control of most operations in an ore dressing plant. The only known approach through which such a calculation can be performed is the population balance model equation. The latest and certainly most significant progress made in this area is the solution proposed by King (1990), which requires one textural parameter that can be measured directly from the ore being studied. The main advantage of King's solution is that it does not require the estimation of hundreds of arbitrary parameters that cannot be independently measured, as required by the existing conventional solutions. However, King's solution relies heavily on a knowledge of the detailed internal structure of the Andrews-Milm diagram (Andrews and Mika, 1975). This has never been measured for any ore. The characterization of the internal structure of the Andrews-Mika diagram requires the measurement of the liberation spectra at several progeny sizes produced by the breakage of monosize, monograde particles at several different grades. In this paper, a procedure based on magnetic fluid fractionation for generating seven narrow-size, narrow-grade samples is presented. Each of these samples was then broken into six progeny size classes in an ultrasonic mill. The one-dimensional liberation spectra of each of the 42 progeny and seven parent particle samples were then measured by image analysis. The measured linear-grade distributions are presented in this paper. The calculation of the correspondent volumetric-grade distributions is discussed.

Jan 1, 1994

By R. M. Oliver

THE Falconbridge property is almost completely covered with over-burden to a depth varying from 60 to over 200 feet. This overburden consists of grave], sand, and boulder, with bands of very fine silt, and there is usually a layer of water-bearing quicksand adjoining the r:ock surface. In previous shafts sunk at Falconbridge, this water-bearing quicksand had given considerable trouble, and further difficulties were expected in sinking No. 5 shaft, due to its greater size. The method described in this paper is the one adopted in sinking this shaft, after the matter had been carefully considered. No. 5 shaft is located 2,400 feet east of the old main No. l shaft, and is sunk in norite in the hanging-wall of the ore-body, which is, however, ? practically vertical to the deepest known intersection. The greatest depths of overburden prevail on the south side, or footwall, of the ore-body, and this, together.. with the fact that the footwall is wet and more badly fractured, swayed the final decision to sink in the hanging-wall. After the shaft site had been chosen and cleared, a diamond drill was set up a few feet away and a hole bored to a depth of 405 feet to test the over-burden and character of the norite bedrock. The depth of overbudren indicated by the hole was Ill feet, with the last 10 feet water-bearing. The norite was rusted and broken up for only a few feet below bedrock. A steel sinking shield (Figure l) was assembled at the shaft location, and consisted of 5/8-inch plate, 5 feet deep, built around a frame of 6 inch by 6 inch angle-iron, and braced at the corners with the same material. Twelve-inch I-beams held the shield as rigid as possible. In order to reduce binding against pebbles to a minimum, the shield was constructed with a 1-inch batter on all sides.

Jan 1, 1938

By G. I. D. Roach

The leaching, with hydrochloric, sulphuric and perchloric acids, of suspensions and massive specimens of different haematite and goethite samples has been studied. Both accelerating and constant types of leaching curves have been observed. It is concluded that the grain to particle size ratio of the oxide being leached determines which type of leaching curve is obtained, particles containing a large number of individual grains producing the accelerating type of curve

Dec 1, 1971

By Juan L. Sepulveda

An MPSI KW-20 Tower mill has been tested at the Butte Molybdenum plant of Anaconda Minerals Company, as a substitute for the conventional 1.5x3.0 m (5x10 ft) tumbling ball mill currently used for regrind purposes. The Tower mill was operated in both open and closed continuous circuits. These results were complemented with a series of batch grinding tests to determine some of the operational features of this mill. The relative grinding efficiency of the Tower mill with respect to the tumbling ball mill was determined and the applicability of this new mill to a plant/heavy duty environment was assessed. Experimental results obtained on the regrind of moly concentrates indicate that approximately 40% energy savings can be realized by using the Tower mill instead of the ball mill.

Jan 1, 1984

By Michael Gauna

A high seam geologic condition exists at Jim Walter Resources No.4 mine which requires immediate rib support after a continuous miner cuts a place, High seam mining heights are typically 2.4 to 2.6 m (8 to 9 it) and a thick rock layer is present in the upper portion of the coal rib side. The 610 m (2000 ft) mining depth at No. 4 mine induces horizontal rib line movement after excavating an entry. Horizontal rib movement greater than 30.5 cm (12 in) have been noted. When lateral movement occurs in the high seam areas, the thick rock layer, and the coal above the rock layer, become fractured and tend to roll into the entry. If not adequately supported, large rib rolls develop in the place being bolted as well as in previously mined areas which endanger men and equipment. To control this situation rib support must be installed in the roof bolting operation as the bolting crew works towards the face. A rib control system has been developed for this high seam mining condition utilizing a mechanical anchor bolt placed at an angle in the rib and installed with a modified Fletcher DDFI- 15 bolting machine. Over 120 km (75 mi) of entry have been supported with angle rib bolts. These angle bolts constitute 43 to 60% of the total roof and rib bolt footage in the high seam port- ions of No.4 mine. The angle rib bolting system has proven safer, more effective, and more efficient than the earlier support method employing bolts installed horizontally into the rib. No rib roll accidents have occurred since the angle drill bolting machines were placed in service in 1981. By securing the broken rib material with an angle bolt anchored above the coal pillar, a more effective means of rib control is achieved. Angle rib bolting does not interfere with continuous miner productivity. In addition, bolting crews are now reduced from three to two people and the total drilling supply costs are approximately 60% the previous cost, when compared to the previous support method using horizontal rib bolts.

Jan 1, 1983

By Ry Stone

"There have been many design practices utilised within the coal mining industry to arrive at the minimum densities of primary ground support required during roadway development. This paper demonstrates the practical use of empirical databases, and focuses on the main drivers for ground support as demonstrated in conceptual models.Golder Associates’ empirical databases used for ground support include a Primary Roof Support Database and a Primary Rib Support Database. Both are based on successful ground support designs installed in mines in Australia, the US, the UK, South Africa, New Zealand, and Europe. The term “successful” refers to those designs that were used on a repeated basis for the purpose of roadway development.The Primary Roof Support Database indicates that the major factors influencing successful roof support designs are roof competency, expressed as the Coal Mine Roof Rating (CMRR), and in situ stress. As roof displacement is essentially a function of horizontal stress and roof competency, in order to provide some form of measure as to the likely magnitude of roof deformation during roadway development, the depth of cover is divided by the CMRR to arrive at a “Stress Strength Ratio” (SSR). The database indicates that the higher the SSR, the greater the likelihood that the roof will require higher densities of support.In regard to the Primary Rib Support Database, it is evident from the current database that the primary factors affecting the capacity of rib support required for a successful design are roadway height and depth of cover. In order to provide some form of measure as to the likely magnitude of rib deformation during roadway development, the depth of cover is multiplied by the height of the roadway to determine a “Rib Deformation Rating” (RDR). Similar to the roof, the database indicates that the higher the RDR, the greater the likelihood that the rib will require higher densities of support.These databases have been used to help determine the minimum primary ground support designs required at many mine sites in Australasia, Europe, and the US. This paper will demonstrate the effectiveness and practicality of these databases at two selected mines in Australia and the US.In order to improve the Primary Rib Support Database, this paper will also propose a new rib deformation rating based on the addition of site specific coal strength data for the Australian mines. The proposed rating attempts to capture the main variables that define the behaviour of a buckling column."

Jan 1, 2015

By Fouad Faraj, Julian M. Ortiz

Within the natural resource industries, there is an increasing amount of data and number of variables being recorded when sampling a site. This has made multivariate geospatial datasets more difficult to analyze, in particular the definition of estimation or simulation domains used in geostatistical analysis. Establishing these domains is typically the first step for any subsequent geostatistical workflows or modeling. Domains are traditionally established using categorical data such as lithology, mineralization, or alteration from geological logging and are aimed at identifying distinct populations with particular geological, spatial, and statistical features. The manual logging process is time-consuming and costly but is required because defining geologically homogenous volumes is crucial for the planning, extraction, and processing of natural resources. Classical clustering methods have aided in analyzing the multivariate datasets, but the resulting clusters from these methods do not correlate well with geological logging and do not allow practitioners to input their knowledge of the domain in the clustering process. In this work, a simple unsupervised classification workflow is presented which allows the practitioner to input domain knowledge by selecting relevant variables to cluster reasonable geological domains. This can be used as a tool to aid the manual logging procedure or as a tool to establish domains for different uses such as defining zones with different rock hardness distributions which allows the corresponding volumes to be sent to appropriate mills for efficient mineral processing. The performance of the workflow is assessed on a mining dataset using the geochemical information and validated with the geological logging.

Apr 16, 2021

Between 1966 and 1976, Australia moved from being a non-producer to a position of meeting more than ten per cent of world nickel demand. New mine developments beginning the early-1990s have the promise of more than doubling the country's world market share - from around eight per cent to perhaps close to 20 per cent. This new surge in activity - the so-called `second nickel boom' - has led to several developments which seem likely to have similar economic impacts to those of the late- 1960s and early-1970s. There are, however, some notable differences this time around. The impact of long distance commuting over the past 30 years has changed the regional development scenario. The gold industry is much stronger in Australia than it was in the late-1960s and this helps to place the importance of new nickel discoveries in a more realistic perspective. As potential players have jockeyed to complete feasibility studies and move into construction and production phases of new long-life mines, established suppliers clearly seem to be taking actions to discourage the newcomers. In what appears to be a classic oligipolistic market situation, the heightening of perceived entry barriers to the industry appears to be a particularly visible strategy undertaken. In the current scenario as well, greater vertical integration among producers appears a significant influence on market power.

Jan 1, 1996

By R-H Yoon

The thin film pressure balance (TFPB) technique was used to measure the kinetics of thinning of single foam films and disjoining pressures in the presence of sodium dodecyl sulfate (SDS) and electrolyte (NaCl). The results were analysed in view of the Reynolds equation to determine the role of surface forces in film thinning. It was found that film thinning is controlled by surface forces at thicknesses below approximately 200 nm. It was also found that hydrophobic force plays an important role particularly at low SDS and NaCl concentrations. The values of the hydrophobic force constant (K232) estimated from the film thinning experiments were used to predict the disjoining pressure isotherm using the extended DLVO theory, which were found to be in excellent agreement with experiment. The TFPB technique was also used to measure the equilibrium thicknesses (He) of the foam films stabilised by a non-ionic surfactant, n-octanol, in the presence of NaCl. At a given ionic strength, He increased noticeably with increasing octanol concentration at very low concentrations. This observation suggests that hydrophobic force is at its maximum level in the absence of surfactant and decreases with increasing surfactant concentration. The results obtained with the single foam films were used to explain the stability of the three-dimensional foams.

Jan 1, 2005

By Yuting Xue, Khaled Mohamed

Rib control is a critical component of underground coal mining operations, and comprehensive rib support design is essential for ensuring the safety of miners. However, there is currently no standardized approach for rib support design in the United States. To tackle this issue, the National Institute for Occupational Safety and Health (NIOSH) has developed a standalone application, Design of Rib Support (DORS), for rib stability assessment and rib support design under development load. The rib support design in DORS starts with the rib support density, which is determined from the unsupported rib factor of safety (RibFOS). The relationship between rib support density and unsupported RibFOS was obtained from the collected field data. The objective of this research is to validate DORS rib support design by analyzing the extent to which the proposed design capability was utilized to support the coal ribs using numerical simulations. A series of numerical models with varying overburden depth and rib height were built and the ribs were supported with the DORS-recommended rib support design. The bolt load was analyzed under different conditions and the results show that bolt load varies with the overburden depth, the location of the bolt and bolt length. The load in the bolt(s) increases with the reduction in unsupported RibFOS. The bolt(s) start to yield when the unsupported RibFOS falls below a threshold value of 0.8 and secondary support is necessary.

Jun 25, 2024

By Leonard Weixler, Peter Halbach, Michael Jarowinsky, Johannes Post

Germany as an industrial nation is highly dependent on the import of mineral or metal resources. Sources which have not been considered until now are the marine mineral resources (MMR), which in recent times are enjoying more and more increasing interests and which might provide in the future a considerable contribution to the supply security on metal resources not only for the industrial countries. Backed up by the German government’s "National Masterplan Maritime Technologies" (NMMT) and corresponding industrial R&D-activities, the idea and the advantages of deep-sea mining is gaining more and more interests and supporters with respect to industrial and political considerations on strategic raw material resources as well as on the development of deep-sea mining technologies. The NMMT aims to initiate growth and increase the competitiveness of the German maritime industry on international markets and covers about 10 different marine and ocean technology sectors including deep-sea mining.

Sep 1, 2014