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By Jean-Michel M. Rendu

According to statistical theory, the geostatistical methods of ore reserves estimation are greatly superior to any other method. However acceptance of geostatistics by the mining industry has been slow and not as wide spread as one would expect. One of the reasons for this cautious approach is that it is often questioned whether the geo- statistical assumptions are satisfied in real world situations. When blocks of ore are estimated in a mineral deposit, geostatistical theory can be used to determine which method of estimation should give the best results. Using this theory, the relationship between estimated value and true block value can be quantified. There is a need to verify that this theoretical relationship is actually observed in practice, and that the block estimates ' obtained using the theoretical ly best method of estimation, are actually most similar to the true block values. In this paper the results expected according to the theory are compared with the results actually obtained. Sample values from a large bedded gold deposit have been used. Blocks of ore have been estimated by a number of methods, including the polygone, inverse power of the distance, kriging, logarithmic kriging and other geostatistical methods. The block estimates have been calculated from samples on a large grid, and compared with the true block values obtained from additional samples on a much smaller grid. The results of this comparison show extremely good agreement between theory and actual results.

Jan 1, 1979

By C. M. Loeb, A. M. Gaudin, J. H. Brown

THE object of most size reduction operations in the mineral industry is to liberate the grains of valuable minerals in the ore from those of the gangue. This is usually accomplished by crushing and grinding the entire mass of ore until there is only a small probability that any single particle contains more than one mineral. During this size reduction only limited control exists over size or composition of the particles exposed to the breaking action, and there is no control over the paths followed by cracks generated during the operation. This lack of control usually results in overgrinding and in production of large quantities of very fine material. The first detriment, overgrinding, is costly in itself, but when combined with the second factor it is doubly so. Not only is the fracture of a free particle unnecessary-the fracture of these particles may also make subsequent separation operations difficult, inefficient, and wasteful. It has been pointed out' that if the object of size reduction is to liberate the valuable mineral component of the ore then, ideally, fracture should follow intergranular paths to the exclusion of trans- granular ones. This would result in liberation of the valuable minerals with as little size reduction as possible. This ideal comminution operation is referred to as intergranular comminution, and it was the object of the investigation to determine the extent to which it could be developed by heat treatments.

Jan 4, 1958

By Fisher WJ

The'treatment of the South Alligator valley uranium ores passed through three phases dictated by economic circumstances during the years 1956- 640 In the first phase high grade ores were treated by hand sorting and wet gravity separation for recovery of high grade concentrate to meet a United States Atomic Energy Commission (U.S.A.E.C.) contract for plus 50 per cent pitchblende concentrates. Secondly tailings from the gravity plant and some high grade ores were trucked to Rum Jungle and sold to the Australian Atomic Energy Comm- ission (A.A.E.C.). Thirdly solvent extraction plants were built at Moline (previously Northern Hercules) by United Uranium N.L. (UOU.N.L.) and at the South Alligator River by South Alligator Uranium N.L. (SOA.U.N.L.). These were the first solvent extraction plants designed in Australia, as earlier plants used the ion exchange process for recovery of uranium oxide. The plants were small, indeed the S.A.U.N.L. 15 ton per day plant was possibly the smallest commercial plant known, but they operated efficiently with good recoveries, and were placed on a care and maintenance'òbasis when contracts were filled. Sulphuric acid was supplied in bulk to both plants by the A.A.E.C. from the 30 ton a day acid plant at Rum Jungle. Gold was recovered as a by product of uranium ore from the Moline plant.

Jan 1, 1968

It has been stated, by Sir James M. Barrie, that "the man of science appears to be the only man who has something to say, just now-and the only man who does not know how to say it ". The friendly jibe of the novelist contains enough exaggeration to make it humorous to the followers of Huxley and Spencer; but could any litterateur poke similar fun at the exponents of the avowedly utilitarian branches of science-the men of technology-without suggesting an unpleasant truth? Indeed the engineer does bungle language deplorably. He makes a fetish of efficiency, yet he shows no regard for the effective use of one of his most important tools-the pen; he believes devoutly in accuracy, yet he employs an instrument of precision as carelessly as a small boy handles a gun. This inconsistency may be due to causes such as were indicated by the Academic Senate when it undertook to explain the defective writing of the students in this university.* The Senate suggested that the student is "constantly subjected by his environment to the unedifying influence of myriad examples of poor English", and that he is also affected by "a certain public prejudice against correctness of expression". With these statements most of us will agree. Our local newspapers, for instance, tend to spoil the student's taste for good English; later in life, as an engineer, his daily contact with illiterate men inclines him to careless speech and slovenly writing. As

Jan 1, 1931

By D Akis, A Clark

The Lihir gold operation, located in the New Ireland Province of Papua New Guinea (PNG), approximately 900 km north of Port Moresby, was commissioned in 1997 under the management of the Lihir Management Company, a subsidiary of Rio Tinto. This management period ended in 2005 with Lihir Gold Limited (LGL) becoming self-managed. LGL is now the largest listed company in PNG and a top tier mining company in Australia. The focus of the operation since 2005 has been to take advantage of strong market conditions to increase cash flow while driving operating costs into the lowest quartile of gold producers. During this period production has increased through capital expansions, most notably with the addition of a flotation circuit, and through culture change and efficiency improvements. The next step forward for the Lihir operation is a major plant upgrade to increase production to an average of around one million ounces per annum by matching the ore processing rate to the ore mining rate. The key benefits of this project will be the addition of approximately 240 000 ounces per annum of gold production, the access to an additional one million ounces of gold and the ability to meet all stockpiling requirements. The Lihir operation has come out of the boom period in a strong position, is undertaking a major upgrade at a time when prices are low and labour is available, and will be positioned to take advantage of future opportunities as they arise.

Jan 1, 2009

By William G. Gates

INTRODUCTION The Heath Steele mine is located in the Bathurst-Newcastle area of northern New Brunswick. It is jointly owned by American Metal Climax, Inc. and the International Nickel Company of Canada who hold a 75% and 25% interest, respectively. The ore deposits of lead, zinc and copper sulphide occur in very fine grained pyrite and/or pyrrhotite masses. A consistent spatial relationship with a quartz feldspar porphyry is characteristic of these deposits and the many other similar sulphide deposits in the district. The two principal mineral assemblages of pyrite-sphalerite-galena, and pyrrhotite-chalcopyrite-pyrite, occupy characteristic positions relative to the enclosing rocks. This feature and the nature of the sulphide mineralization are described and the variations in metal content are noted .with special emphasis on the lead-zinc ore zones. The mine product ion rate is 3,000 tons per day of a mixed lead- zinc and copper ore which is extracted from the B-1 zone. The complex nature of the ores presents many metallurgical problems. Optimum metal recoveries are achieved when milll feed grades are relatively consistent and proportions of the contained metals are with in acceptable limits. Ore outlines and stoping blocks are delimited by close spaced diamond drilling. From this information it is possible to forecast the grade of any portion of a stoping block. Production from the various stopes may then be scheduled so as to achieve an acceptable mill feed grade.

Jan 1, 1970

By Frank Milliken

IN September 1937, the Ohio Copper Co. inaugurated the treatment of its copper-bearing mill tailings at Lark, Utah. These tailings had been accumulated during the regular operation of the Ohio Copper mine and mill over the period 1007 to 1019. Gravity concentration had been employed except for a comparatively short period in 1919, when flotation was used. The ore milled during that period assayed about I per cent Cu. The chief copper mineral, chalcocite, was dissemi-nated in a shattered quartzite, mainly along fracture or cleavage planes. The quartzite gangue was extremely hard and grinding to liberation resulted in excessive sliming of the "sooty" chalcocite, with consequent high tailings losses. Recovery on the seven million tons treated was prob-ably less than 6o per cent of the total copper content. As early as 1918, attempts had been made to sample the dump. In 1928, a com-plete sampling program was undertaken. The sampling consisted of seventy-four 5-in. post auger holes drilled to the full depth of the dump at regular intervals of 250 ft. Each 10-ft. portion thereof com-prised a sample for analysis. Each sample was screened, rolled, divided into three parts, dried and assayed. The reject was retained for testing purposes. From the depth of the auger holes a contour map of the dump was plotted, Fig. 1, which gives percentages of tonnage and copper content.

Jan 1, 1940

By G. A. Rowell, T. M. Barczak, J. C. Zelanko

The US Bureau of Mines conducted a multifaceted geomechanics research project at a bump-prone longwall coal mine in eastern Kentucky. This mine presented a unique opportunity to study coal mine bumps because the problem appeared to be confined to areas beneath a sandstone channel of limited areal extent. The Bureau's research plan sought to exploit the uniqueness of the site by monitoring strata behavior and longwall support reactions as the longwall face approached and passed beneath a sandstone channel. The study incorporated static pillar stress and strata deformation measurements, shield support leg pressure measurements and microseismic monitoring, as well as geologic mapping and the collection of observational data. Data collection was underway when a major coal bump occurred on the longwall face at the mine. Pillar behavior (load and deformation), shield loading and microseismic activity were monitored prior to, during and after the bump. Observations in the tailgate indicated that these pillars were failing prior to and following the face bump. Shield load data, evaluated in an effort to identify trends that could be used to forecast coal bumps, appear to provide a measure of the effectiveness of destressing operations conducted on the face (e.g. shot firing). Analyses of microseismic data revealed anomalous values associated with microseismic "energy" prior to the face bump. In addition, microseismic source-location data and underground observations provided some insight as to the sequence of pillar and face bumps.

Jan 1, 1992

By John Carter Anderson

The theory of a zonal deposition of ores from ascending solutions which were differentiation products of a cooling magma, first propounded by Spurr,l in a measure explained by Lindgren,2 and recently re-emphasized by kemp,3 while perhaps accepted in principle by many mining geologists, so far has not been accepted as capable of practical application in the study and development of ore deposits. From his observations, the writer is convinced that there are laws governing the primary deposition of ores which, when properly worked out, will be of greatest economic value; and that the application of this knowledge to the development of new mines will mark an advance in the mining industry similar to that following the working out and application of the theory of secondary enriehiment. That there has been a tendency to a zonal distribution in the formation of ore deposits, by which the ores of one metal have been precipitated from tile mincralizing solutiolis at a greater distance from the source than those of another, cannot be disputed; and the nature of this zoning in a given deposit or district has been frequently described.4 But that a selection precipitation of the ores of two or more metals, other than lead and zinc, in successive zones may have taken place in a single deposit within limits economically possible of exploration is not generally recognized or admitted.

Jan 1, 1923

By Naj Aziz

Both bolt profile shape and spacing (rib spacing) have been found to influence the bonding capacity of the grouted rock bolt. The bolt surface profile configuration has greater importance to rock bolting in strata reinforcement in mining than the steel rebar used in civil engineering construction. This is because a rock bolt in mining usually is subjected to greater dynamic loading than the steel rebar in civil engineering construction. The increased bonding capacity of a bolt is important when supported ground is either heavily fractured, faulted or the supported ground is of soft formation, typically that of coal measure rocks. Past laboratory studies have identified the bolt profile spacing as of significant relevance to bolt resin rock bonding increase, however, no attempt has been made to determine the optimum spacing between the bolt profiles spacing. Accordingly, a series of laboratory tests were carried out on 22 mm core diameter bolts, commonly used in Australian mines, installed in cylindrical steel sleeve. The study was carried out using both push and pull testing methods. The push test was carried out in 150 mm long sleeves while the pull testing was conducted in 115 mm long sleeves. Profile spacing tested include, 12.5, 25.0, 37.5, and 50 mm lengths. Additional studies undertaken include modelling the profile of the load-displacement data of pull testing. Bolts with a profile spacing of 37.5 mm were found to provide optimum load bearing capacity as compared to other tested profile spacings.

Jan 1, 2009

By S. L. Crouch, C. Fairhurst

The general term "coal mine bump" refers to the sudden and violent failure of in-situ coal. Coal bumps occur in most countries where coal is worked by underground methods. They are related to geological factors and mining techniques. Coal bumps can be characterized as unstable releases of energy associated with yielding that occurs with progressive mining. Unstable releases of energy occur when the coal is able to absorb less energy than is released by the surrounding rock mass during the yielding process. At any stage of mining, the amount of excess energy so released is governed by the mining geometry, the overburden stress, the elastic properties of the rock mass, and the stress-strain characteristics of the seam material. If the coal in the vicinity of the working face is crushed, the peak abutment pressure occurs at some distance into the intact portions of the seam, and mining takes place in essentially destressed coal. With subsequent mining, additional yielding occurs, excess energy may be released, and the peak stress is again shifted into the solid. This process continues until the mining geometry is such that the zone of peak stress is effectively surrounded by yielding coal, at which point it can be anticipated that further mining will produce dramatic redistributions of stress and be accom¬panied by large releases of energy. On this basis, the differences between several alternatives for mining a given block of coal may be pronounced.

Jan 1, 1975

By George A. Packard

WHEN, in April, 1892, the writer began experimenting with the cyanide-process, it had already proved a success in the treatment of tailings, but had not become an important factor as a primary method of ore-treatment. The Livingston, Colorado, mill was running a few small agitators; the Mercur mill, in Utah, was said to be a success, but was " closed down to increase capacity; " and Mr. A. B. Paul, in Shasta county, California, was running ore'through a stamp-mill into leachingvats, using a weak cyanide solution in the battery. Mills had been, or were being, erected in Arizona; on the Comstock lode; and in South Dakota. Some of these never started, and several were shut down or remodelled for other processes. Altogether, the outlook was anything but favorable. Many of these mills were planned to make use of agits tion, and a cyanide solution containing at least 1 per cent. of potassium cyanide was employed. Since then the improvement of the process, both chemically and mechanically, has placed it among the recognized successful methods of oretreatment. Within the past year I have visited a large number of cyanide-mills, and have collected considerable data, of which I publish enough herewith to give an idea of the development of the process and of the methods followed in the principal mills. I would say, however, that nearly all of these plants are experimenting, most of them employing experienced chemists,

Jan 1, 1897

By E. J. Rapperport, J. P. Pemsler

Proton irradiation of high-purity distilled berylliuwz was utilized to introduce various hydrogen contents from 0.00075 to 0.075 at. pct (0.83 to 83 ppm) in a band 0.004 cm wide. After irradiation, the specimens were heat-treated to effect hydrogen agglomeration. Observations of agglomerates in all specimens of the lowest hydrogen content indicate a hydrogen solubility of less than 0.83 ppm in the temperature range 350" to 1050°C. Estimates of the inter diffusion coefficient in the hydrogen solid solution of beryllium were obtained from measurements of the dimensions of hydrogen-depleted zones survounding agglomerated bubbles. A value of (approximately) 3 xlo-' sq cm per sec is obtained for the diffusion coefficient at 850" to 900°C. PREVIOUS investigators found that We solubility of hydrogen in beryllium is very small. Gulbransen and Andrew' state that beryllium does not react with hydrogen at 23 mm Hg between 300" and 900°C. Cotter ill et a1.' report that as-machined beryllium has an adsorbed hydrogen layer of 0.007 cu cm per sq cm of surface. No additional hydrogen is picked up in hydrogen at 0.1 mm Hg and between 200" and 80O°C, or when hydrogen is bubbled through molten beryllium. Beryllium hydride has been reported to exist in an ether solution,394 but decomposes at about 200°C; there is no substantial evidence for the existence of the hydride in the solid phase.

Jan 1, 1964

By Henry M. Howe

in Cast-Iron. It has been generally accepted that the presence of silicon in cast-iron leads to the formation of graphite; and this has been explained by saying that the silicon lowers the solvent power of iron for carbon at and somewhat below the freezing-point, so that, in the presence of silicon, the iron is unable to retain in solution or combination the whole of the carbon with which it has united while molten, and therefore expels the excess of carbon in the form of graphite, during and immediately after solidification. Probably the best way to study this question would be to examine pure cast-irons, i.e., those containing nothing but iron, carbon and silicon, which at the same time should have been saturated with carbon when molten. But the data for such a study are not at hand; so we must turn to commercial pig-irons as they are made in the blast-furnace, and before their composition has been changed by remelting. Much evidence has been offered of late, tending to oppose the theory of the action of silicon above set forth. Some of this evidence will be examined here. 1. Mr. Bachman's Results. In particular, Mr. F. E. Bachman† has published a collection of analyses of cast-iron, in which the proportion of graphite at first appears to be nearly independent of the proportion of silicon present. Thus, in his Table LI., we find that with pro-

Jan 1, 1901

By Collin Bartlett, H. Storch

"Modern metallurgical processes operating with oxygen enriched air, such as the Outotec Flash Smelter and Flash Converter, generate very concentrated SO2 off-gas, which in combination with Outotec sulphuric acid plant technology allows the production of high pressure steam to be used for power generation. Outotec combines well proven technology of sulphur burning plants for this purpose with metallurgical plants.The application of Outotec’s proven LURECTM process enables processing of SO2 gas of up to 25 vol.-%. This process maximizes the energy recovery from the SO2 oxidation at a suitable high temperature level which can be turned into high pressure steam. The application of the Outotec HEROSTM heat recovery system enables the generation of low pressure steam from the absorption energy released at the intermediate absorption step. Additionally, energy is also recovered in the acid coolers for boiler feedwater pre-heating.The concept of integration of high and low pressure steam in combination with the pressurized operation of the boiler feedwater deaerator, thus heating up the boiler feed water to temperatures around 160…170°C, enables indirect transfer of low pressure steam (for deaerator operation) into more valuable high pressure steam, which improves the degree of heat recovery. This is the characteristic of Outotec’s HEROS+TM process.The increased generation of high pressure steam will in turn enable the generation of more electricity when compared to a standard traditional sulphuric acid process."

Jan 1, 2014

The basic methods to remove material from underground mines are to: convey continuously, batch in trucks, or batch in a shaft hoisting system. A critical aspect in shaft hoisting is accurately batch loading the conveyance or skip. During the 20th century, the almost universally accepted method of loading was via a measuring flask. A measured quantity of material was filled into the flask as the conveyance traveled through the shaft and then, when the conveyance arrived at the loading position, it was ædumpedÆ into the skip for hoisting. Two skip loading conveyor systems have been developed in Australia: BHP BillitonÆs Cannington Hoisting System, installed in 1996, is believed to be the first conveyor loading system designed for two skips. Two parallel conveyors were installed with a two-way gate controlling feed onto each belt. Cannington was ideally suited to conveyor loading as the very high ore density and relatively low production rate required a relatively small volumetric storage capacity on the weighed belt. Newcrest MiningÆs Telfer Hoisting System, which is to be commissioned in 2005, consists of a single slewing conveyor loading each skip with 32 tonnes of ore. The development of this system eliminates the two-way transfer, improves the accessibility and minimises the excavation required. While every hoisting system must be considered on its merits, conveyor loading offers significant advantages to the Mining Industry in the 21st century.

Jan 1, 2005

By G E. Frantii

In the exploitation of low grade mineral deposits, blasting engineers are vitally concerned with maximizing the efficiency of explosive fracturing of rock while simultaneously limiting deleterious environmental affects to acceptable levels. Efficiency can be inferred from radiating seismic waves. Likewise, seismic waves carry direct information on damage potential. The usual approach to this problem is to measure the maximum signal level close to a blast, where it is difficult to instrument and where the signal complexity is intensified by mixtures of wave types and by local heterogeneities. Near-field sites are usually more easily monitored and more readily interpreted. Therefore, a study is being conducted to determine if variations in multi-hole, delayed blasts produce measurable changes in the spectra of seismic waves recorded in the near-field and if these spectra can be correlated with close-in strong motions and affects. To date, power spectra for the well-developed phase Lg and its early coda have been computed and are found to vary measurably when nominal changes occur in blast conditions. Up to a distance of about 50 km the spectra of Lg and its coda appear to be dominated by body wave characteristics (thus source-controlled), whereas beyond 50 km path affects seem to dominate. Additional data must be collected to fully explore the consistency of near-field Lg observations and to verify their usefulness as diagnostics of the engineering affects of blasting.

Jan 1, 1977

By Arkady Senchenko, Sergey Rybkin, Svetlana Lagutina, Alexander Aksenov

"The application of autoclave leaching technology for sulfide concentrates containing base and precious metals is spreading nowadays. In the process of concentrate leaching silver accumulates in the forms of jarosite compounds, transforms into passive chemical state and is mostly found in solid phase. Effective technology development for silver recovery from solid phase of concentrate autoclave leaching raises the necessity for comprehensive research of silver forms of occurrence and their properties in this product. The possible form of silver presence in solid phase of concentrate from autoclave leaching is argentojarosite. This article is about the study of physical and chemical properties and structure of synthetic argentojarosite - AgFe3(SO4)2(OH)6. A method of argentojarosite synthesis has been developed under conditions simulating the process of autoclave leaching of sulfide concentrate, and includes silver dissolution in the form of Ag2SO4, Fe3+ sulfate hydrolysis, AgFe3(SO4)2(OH)6 build-up. X-ray data of synthesized argentojarosite completely correspond to those of natural mineral. The structural formula of this complex compound has been studied and confirmed. The chemical properties of synthetic argentojarosite, its solubility in acids and alkalis have been investigated. Phase changes when heating argentojarosite with the build-up of iron oxide and silver sulfate stop at the temperature equal to 650 ºC. Based on the results received the technological solutions for solid phase of autoclave leaching of concentrate have been developed with silver recovery of 95-98%."

Jan 1, 2014

By Brien A. Perry, Art Wiebert

"Many organizations which have implemented Total Quality Management (TQM) are finding that the process has either stalled or is not working so well as originally envisioned. This can be particularly evident in an engineering environment where the uniqueness of engineers and their particular culture has not been adequately considered. Winning the commitment of a highly educated group ojprojemnnJJ1s to the TQM concepts, which are often initially 5W2 as too simplistic poses special challenges.Successful TQM implementations are found among technical groups where employees have significant input into creating the new work culture, feel empowered to make changes and are well trained in teamwork. A coach who is knowledgeable in implementation problems can, when working closely with the technical teams, help them circumvent obstacles and guide them successfully through the difficult early phases. The remaining key ingredient for success is supportive management which leads the change and is both informed and appreciative of the accomplishment being made.This Paper is based on first-hand experience with common problems and results encountered in implementing TQM in an engineering environment. Described in the paper are ways of avoiding these problems through awareness of the unique nature of engineering groups, implementation planning, just-in-time training and coaching people in the TQM process. The paper concludes with a focus on the opportunities and results from a successful implementation. These opportunities and results include the benefits each engineer can realize through process thinking, empowerment and teamwork."

Jan 1, 1995

By K. L. Ludeke, A. D. Day

For many reasons, it appears that deep rooted, perennial shrubs offer potential for improved stabilization and provide maintenance free vegetative cover to harsh sites where perennial grasses have not been successful. The major objective was to select various shrub species of arid plants for initial soil stabilization of disturbed mining areas. The very fact that a drought-adapted shrub has a massive root system that can use moisture from a greater volume of mineral waste soil materials suggests that arid environment disturbed soils may be vegetatively stabilized using desirable forage shrubs. A secondary effort is underway to assemble information and plant materials of promising species from many arid regions of the world for reclamation of mined lands. Surprisingly, many of the better plants for arid sites are quite high in protein content. With proper management, breeding, and selection, they may prove to be very desirable livestock feed when mined lands are used in range land areas. Advancements in arid land solid waste stabilization hold favorable promise for many industries that mine and mill in arid regions for effective reclamation of disturbed areas. Particularly exciting is the possibility of establishment of high density maintenance free vegetative cover of climax vegetation that reclaims the disturbed area back to its original land use. Due to high shrub productivity, stabilization potential, nutritional quality, and reclamation success, greater use should be made of shrubs in disturbed land reclamation associated with mining and milling operations in harsh aril environments.

Jan 1, 1986