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By H. J. Glass

Collection, preparation, and analysis of blasthole chippings is expensive. Frequently, interpolation of grades at unsampled locations is considered using techniques like kriging. A pre-requisite for kriging is that an experimental variogram is established. In order to assess the quality of the experimental variogram, a measure is developed in this paper. The measure is derived from analysis of the time-honoured expression relating the variance, semivariance, and covariance. It reflects the weighted average deviation of the summed semivariance and covariance from the biased variance. The proposed measure allows assessment of the influence of key variables on the quality of the variogram. Using simulated data, it follows that the quality improves with an increasing number of samples, increasing density of the sampled locations, increasing regularity of the sampling pattern, and increasing uniformity of grades in the absence of correlation. Application to real data shows that the minimum number of samples could coincide with a marked decrease in the value of the measure. Establishing a threshold value is subject to further research. Keywords: variogram, variance, covariance, semivariance, minimization, sampling.

Jan 1, 2003

By A. Muwila

Hercules? is a low nickel austenitic stainless steel developed at Mintek that has a typical composition of 9 wt% Mn, 0.05 wt% C, 2wt% Ni, 0.25 wt% N and 16.5 wt% Cr. A more corrosion resistant version of Hercules? (Hercules? B) with 0.5 wt% Mo has also been developed. Potentiodynamic tests performed on Hercules? B in a 5wt% sulphuric acid solution showed it to have improved corrosion resistance comparable to that of AISI 304. The effect of a varying Mn content on the corrosion resistance of Hercules? B has also been investigated and the results discussed in this paper. From the corrosion test results, it is clear that decreasing the Mn content of Hercules? B increased the corrosion rate, while increasing it decreased the corrosion rate. Keywords: austenitic stainless steel, % ferrite, molybdenum, manganese, nitrogen, electrochemical corrosion tests, potentio-dynamic scans, microstructure, chemical analysis.

Jan 1, 2007

By M. J. Leeuwner

Computational fluid dynamic (CFD) modelling is used to research the complex flow structures that exist in a hydrocyclone. By simulation of a two phase (water and air) flow system, the internal flow and multiphase interactions are investigated. The suitability of CFD modelling as a design tool is further evaluated by examining the effect of varying device dimensions. Three hydrocyclone geometries, used in previous studies, are specified. A transient simulation approach, which employs the Reynolds Stress Model as turbulence model and the Volume of Fluid model as multiphase model, is followed. Results are validated qualitatively against experimental measurements from the previous studies. Keywords: CFD modelling, hydrocyclone, Reynolds stress model, multiphase flow

Jan 1, 2008

By E. C. Hoeman, W. C. Stoecker, R. C. Redfield

"INTRODUCTION Industrial sands, characterized by specific physical and chemical proportion, are,essential new materials for the manufacture of glass, sodium siliante and other products. Sands of suitable characteristics are used extensively for molds and cores in the casting of metals as a granular medium in municipal water filters, as abrasives, as traction sand to prevent the slipping of driving wheels of self-propelled vehicles on trucks and in various ceramic and other structural forms. In addition to the use of common silicon sands in concrete, cement, and mortar, special sands find use in sand-lime brick oxychloride cement, and flooring, for coating prepared roofing, and for placing ware in saggers although sand for sandpaper has been mostly displaced by other harder mineral or synthetic grains, other abrasive uses are numerous and include sandblasting stone sawing, glass burnishing and finishing."

Oct 1, 1945

By I M. Platten, Y Xie, B W. Cuffley, S C. Dominy

"Geometallurgical programs require the collection of representative samples for geochemical, mineralogical and metallurgical test work. Such protocols must be designed to suit the style of orebody in question. The distribution, proportion and size of gold particles have a direct impact on the effectiveness of sampling and test work protocols, and the gold recovery processes employed. Characterisation studies focusing on ore mineralogy, and gold particle deportment, size and distribution are required. High resolution X-ray computed tomography provides a non-destructive method for analysing the 3D nature of gold in rock samples. It can be used to calculate the modal abundance, particle size and distribution of gold in the sample volume. This paper presents a case study of the imaging of in situ gold particles in a high-grade gold ore. The Nick O’Time reef system comprises laminated quartz veins, which locally bear extreme grades of up to 100 oz/t gold. The mineralisation has previously been characterised from both a mineralogical and metallurgical perspective. Eight visible gold-bearing vein samples were scanned using X-ray microtomography. Microtomographic data were integrated with previous mineralogical and metallurgical test work outputs.CITATION:Dominy, S C, Platten, I M, Xie, Y, Cuffley, B W and O’Connor, L, 2016. Characterisation of Gold Ore from the Nick O’Time Shoot (Tarnagulla, Australia) Using High Resolution X-ray Computed Tomography, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 241–254 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By Mark Ferra

Flotation is used in mining to produce concentrates of copper, gold and several other valuable ores. In 2017, a copper mine near Globe, Arizona improved their rougher cells productivity using technically advanced electro-hydraulic actuators in the flotation process by enabling excellent tank pulp level process stability. The new actuators controlled the dart valve position to allow pulp to leave the cell. Tank cell pulp level can change due to feed and discharge fluctuations from neighboring tanks. When traditional pneumatic actuators are used, they have sluggish response times and overshoot due to the inherent physical property of air being compressible. Electro-hydraulic actuators have the benefit of hydraulic stiffness to deliver accurate and repeatable (0.1%) dart valve positioning. The froth layer has more opportunity time to maximize mass transfer into the launderer. The results are an increase in copper recovery by 2-4%. INTRODUCTION In 2013 there was an international flotation technical conference well attended by respected flotation specialists for both mining companies and academia. During the technical session a leading metallurgist was discussing pulp level measurement and said that when he was on the cell deck he stated, pneumatic actuators air cylinders stroking up and down. The presenter then claimed with confidence that "I listened to actuator move so the pulp level in the tank was being controlled!" No one questioned his assumption and I can assert that the audience was quite technical and not shy in their critiques of speakers. The flotation community simply believed that the existing pneumatic technology was enough with no alternative. Having a stable flotation cell pulp level is critical to effective copper recovery. Controlling pulp levels in flotation cells is a complex task that includes modulating dart valves in each cell. The use of REXA Electraulic actuators will decrease the process dead time and maintain froth height in a controlled manner, especially from pulp slurry volume fluctuations from neighboring cells. By reducing flotation cell pulp level tank height variation, a copper mine in Arizona has realized a 2-4% recovery improvement by increasing the froth transfer to the launderers in the rougher cell circuits compared to pneumatic actuators. This paper examines the benefits of using an electro-hydraulic actuator to ensure proper pulp level control and reduce the process operational cost. It will focus on actuator positioning the dart valves to maintain pulp level setpoint at a copper mine in Arizona.

Jan 1, 2019

Rb-Sr measurements on total-rock samples of granitic rocks from the Mount Isa region have confirmed the existence of two periods of granite-forming activity. The Kalkadoon Granite, together with the Ewen Granite and possibly an older phase of the Sybella Granite, has been shown to belong to the earlier age-group at 1760 m.y.; the Wimberu Granite and a pegmatite associated with the Sybella Granite have been dated at 1540 m.y. The initial Sr ratio suggests that the Wimberu Granite may be new material of deep-seated origin.Further Rb-Sr measurements have confirmed previously-reported K-Ar results upon biotites from these rocks, whilst showing that, in this metamorphic terrain, biotites have lost varying amounts of radiogenic Sr and Ar, and therefore yield ages which are younger than the true age of the second event.

Jan 1, 1966

By Albert L. Toenges

[The i~ ortance o~ S3~e, fdequnt, nQ economical tr~n~po~t~t on 8ys~em Th~a bee~ e~~~~siz8d by the introduction of mechanical loading in co 1 mines, pa.rticula:c y \'r~ e::-e ~o?oile loaciine; ~ac~ine!;j rrre u .... ed. This papar i tr_e . eco:1d or' ?. ~eries deGcribi 1{) t:;'~~11>ort:ltion G stems et1-p oyed in mech3JlizeG. f!lincs. Progre,-s ?. epo~ t J...2.t deal t ~~tirel.: ,'Ii th the l:se of rail .laulagr £or c;atl:erine tran~ortc;tion, ailc, in t-!is paper 'Ii 11 be i acuss d c .icilY rub"col'-t? ro ~ t:tto::"ing as Ie _ as ani:naJ., con-",reyor, an ot.he~ systems of rnil gatheri?1.g. ~ho l)urpo~e of this invosti-gation is, as outlined in Progress ,~ort 1, to studT . Q analyz0 v rious systems nov.: in. u"'e El.I1d to derivQ cor..cl :cicn .... tllcrcfrom.]

Jan 1, 1941

By A. Moergeli

The Swiss are building the world’s longest tunnel, the 57-Kilometer (35-mile) long Gotthard Base Tunnel. Lot 252, Tunnel Amsteg: Two Hard Rock Tunnel Boring Machines (TBM) crossed hydro-thermally decomposed granite. While the East TBM advanced slowly but steadily, the West one got stuck for five months and had to be recovered by special means and methods. Both TBMs have finished their more than 11-Kilometer (7 miles) long drives successfully. Lot 360, Tunnel Sedrun: For the first time in tunneling, roadway support machines are used through most challenging, squeezing geology. They constantly advance in full face mode for about one Tunnelmeter/24 hours.

Jan 1, 2007

By P Hunger, H Günter, F Heinicke

High pressure grinding rolls (HPGR) have been used for more than 20 years to grind iron ore pellet feed. Besides coarse comminution (crushing), where HPGR are installed upstream of the ball mill, there are numerous flow sheets where HPGR are used after ball milling and dewatering for re- or finish grinding.There is a clear growing interest in grinding of pellet feed with HPGR during the last few years. In addition to their known advantages of low specific energy consumption, high availability, low steel consumption and improved pelletising processes the lower environmental load (reduced or no water consumption) became a strong driving factor for the application of HPGR in pellet feed grinding.This growing demand increases the interest in better understanding of the HPGR grinding process with fine iron ore concentrates. One of the most important process parameters is the moisture content of the feed material which influences the performance of the HPGR enormously. The HPGR can react to fluctuations of the fresh feed properties to a certain degree by adjusting grinding force and roller speed. Nevertheless, there are limitations by the physics of the compression process and the capability of water absorption by the concentrate. The capability varies for different concentrates and different specific surface areas. This fact has to be considered during engineering of the beneficiation plant.The paper focuses on the influence of feed moisture content on the HPGR performance in view of throughput, increase of Blaine number and process stability on the basis of numerous pilot plant tests, modelling results and industrial experiences.CITATION:Heinicke, F, Günter, H and Hunger, P, 2017. Influence of feed moisture on high pressure grinding roll pellet feed grinding, in Proceedings Iron Ore 2017, pp 187–194 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By P. J. Hancox

Heavy mineral deposits have been known from Liberia since the1950s from both river and beach placers. The heavy mineral content of beach sands ranges between 28?62% and the suite includes ilmenite, rutile, zircon and magnetite. These occur together with kyanite, sillimanite, staurolite and garnet. The average ilmenite content is 82% with minor zircon (11%), rutile (6%) and monazite (1%). The ilmenite is, however, of poor quality with haematite intergrowths and a titanium content ranging from10?42.4% (average ±25% TiO2). The amounts of rutile and zircon, while of suitable quality, have also previously been deemed too low for economic exploitation.

Jan 1, 2000

Mining ventures are essentially risky businesses. Explorers and project developers (plus their investors and financiers) attempt to minimise the risks involved or at least manage them. Core considerations are the obvious technical and commercial risks, but the socio-political system and regulatory environment in which the project will operate can be more important. Successful mineral investments in a country depend upon obtaining realistic and reliable technical results in a country that provides certainty, to gain and maintain investor confidence in a project. Brief commentary is provided on the usefulness of professional accreditation and ethics plus other specific reporting codes (eg JORC/VALMIN Codes) in reducing risks by reinforcing high technical competence and reputable individual professional behaviour (particularly in the context of currently perceived high corruption levels in so many countries). These various risk components are reviewed, especially in a global context, to showcase New ZealandÆs current position. Successful projects are those which provide investors with credible and reliable optimal results in less volatile environments because investors/lenders hate uncertainty and surprises even more.

Jan 1, 2005

The passage of chloroform vapour in a carrier of oxygen through two nickel sulphide ores heated to 380°C converted the nickel to the water soluble chloride form. In one ore the nickel (2·75 per cent) was presentas violarite ((Ni, Fe)3S4) whereas in the second it was present as pentlandite, ((Fe, Ni)9S8) (4·9 per cent Ni).A similar technique was utilized to convert nickel in nickeliferous laterites (1·6 per cent Ni) into a soluble chloride using town gas instead of oxygen as a carrier.With both techniques greater than 90 per cent extraction was achieved.

Jan 1, 1972

By H Firdausi, I Pasek, T Chenier

The Grasberg Block Cave (GBC) Mine is one of the future underground mines of PT Freeport Indonesia (PTFI). Located in the remote highlands of Papua, Indonesia, the GBC mine is scheduled to start production in 2017 reaching its peak production capacity of 160 000 t/d in 2023.In order to reach planned production capacity, the GBC mine will utilise an ore handling system consisting of rail haulage, crushing and conveying. The rail haulage system will utilise over 20 km of track while crushing is accomplished by way of three gyratory crushers each with a capacity of 3300 t/h. Nine conveyors operating in two parallel systems, each system over 3 km in length, will move the ore from the crushers to the stockpiles. These systems require a network of larger tunnels and mass excavations to accommodate the planned production facilities.This paper will describe the ore handling system, tunnel and mass excavation methodology as well as some of the challenges encountered with ground conditions and excavation quality during the execution of the project. A combination of lateral and vertical development methodologies and equipment, including drill jumbos, mechanised raise climbers and specialised ground support equipment, have proven successful in the development of a quality ore handling system.CITATION:Pasek, I, Firdausi, H and Chenier, T, 2016. Development of the ore handling system at the Grasberg block cave mine, Indonesia, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 599–608 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

An effective electrowinning process in hydrometallurgical industry requires fluoride levels in the base metal solution to be less than 10 mg/l. Selective removal of the fluoride ions from base solution is thus desired, if fluoride was added to control calcium and magnesium in the circuit. Consequently, adsorption of fluoride onto activated alumina was studied in a batch and a column set-up. The effects of base metal solution pH, temperature, initial concentration and flow rate on activated alumina performance were investigated in either a batch or column configuration. A two-level factorial experimental design was implemented in studying column dynamics. Results demonstrate that activated alumina is an effective adsorbent for selective removal of fluoride from base solution. In the batch operation, fluoride was removed to values below the maximum allowable concentration (10 mg/[l]) when pH was = 8. In the column adsorption step at 55°C and 600mg/[l] initial concentration, up to 16 bed volumes were processed before breakthrough level was reached. Desorption step using 1% sodium hydroxide solution achieved an elution of 8 bed volumes. The activated alumina (AA) had a capacity of 8.65 gF/[l]AA at the 10mgF/[l] fluoride breakthrough level during the column adsorption test. Keywords: Fluoride; activated alumina; adsorption; recovery; regeneration.

Jan 1, 2009

By K Prendergast, P Dale, I Taylor, A J. Vigar, B Lueck

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Kainantu Project is located within the New Guinea Thrust Belt in northern Papua New Guinea. The area has a long history of exploration and production, with the discovery of alluvial gold in 1928 followed by the discovery of vein deposits of gold and copper at Kora in the 1950s and the current Irumafimpa vein gold mine. Current resources on the Kora-Irumafimpa Vein System (KIVS) stand at 1.5 Moz Au, 5 Moz Ag and 217 Mlb Cu.Mineralisation in the region includes gold, silver and copper associated with mid-Miocene age mafic to felsic intrusions. The KIVS occupies a broad north-west-trending mineralised zone more than 2.5 km long and 200 m wide, with the Kora, Eutompi and Irumafimpa veins on the western side and the Judd and Upper Kora veins on the eastern side. Economic mineralisation occurs in two closely related events occupying the same strongly structurally controlled shearing (quartz-Au-telluride veins and sulfide Au-Cu-Ag veins with free Au) and is best described as a significant intrusion-related event with both epithermal and mesothermal facets that does not appear directly related to known porphyry Cu-Au systems as seen at the surface. Significant wolframite is associated with vein quartz of a slightly older age but also occupies the same shear system.The KIVS occurs within a larger mineralised area of approximately 5 × 5 km. It has complex multiphase intrusions, breccias and diatremes that are only partly delineated by drilling and comprises multiple occurrences of Au-bearing veins and porphyry Cu-Au mineralisation. The area is considered to have high potential for extending the current resources and is being actively explored. The proposed recommencement of mining activities recognises the complexity of the KIVS and later disruptive faulting and will require tighter grade control systems, targeted mining techniques and a gravity circuit to maximise free Au recovery.CITATION:Vigar, A J, Lueck, B, Taylor, I, Prendergast, K and Dale, P, 2015. Kainantu gold-copper system, Papua New Guinea, in Proceedings PACRIM 2015 Congress, pp 601–606 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By E. V. Konopleva, H. J. McQueen, V. M. Khlestov

In addition to increasing grain boundary area during hot working of austenite, the dislocation substructures create potential sites for nucleation of ferrite both at original grain boundaries and at transition boundaries between deformation bands. This development gives rise to a marked increase in the rates of nucleation, of growth and of transformation to ferrite. The combined net effect is product grain refinement that requires less stringent cooling between finish rolling and coiling; hence determination of the above rates would advance process optimization. The important control parameters are the preheat temperature (degree of homogenization), finishing temperature, strain (accumulation near finishing) and the extent of recrystallization after finishing. These effects vary greatly with steel composition; nevertheless, some general rules have been formulated. Moreover, there is also potential for deformation of the refined ferrite. There are other thermo-mechanical processes such as warm forming of metastable alloy austenite to provide a dense substructure that is carried into the martensite on quenching. In other processes, the austenite may be deformed during cooling through the transformation to develop a dense substructure in the ferrite that is stabilized by fine carbides.

Jan 1, 2004

By AIME AIME

FIVE days, extending from Monday, Feb. 18 to Friday, Feb. 22, inclusive, will be required for the annual meeting this year. The first fours days will be devoted to reading and discussion of papers, general and committee business meetings, two lectures, luncheons, dinners and all the pleasures of a big, general reunion. The fifth day will be given over to an all-day excursion for both men and women by special train to West Point, in celebration of the birthday of the first President of the United States. Washington having been an engineer and now after one hundred and thirty-one years the country having selected as President another engineer in the person of Herbert Hoover, our own past president and honorary member, it is proposed to celebrate with a good old-fashioned picnic and inspect the school. The authorities at the Military Academy have undertaken to welcome the engineers and do whatever they may to make our pilgrimage notable. Other social features planned for the week are numerous. Luncheon will be served as usual at the building each day of the meeting to all members and guests. This year a very nominal charge will be made, primarily to overcome deficits due to irregular attendance. Monday noon, the Non-metallic Minerals Committee will lunch at the Engineers' Club and in the evening the Milling Methods Committee will dine there. The Annual Smoker will be held at Hotel Astor after dinner. Professional entertainment of high order is promised, but not too much to interfere with the numerous group reunions that characterize this func- tion.

Jan 1, 1929

By Jan C. Still

The Haines-Klukwan-Porcupine subarea of the Juneau Mining District (JMD) is located in the northern portion of the JMD and consists of the land between the Alaska-British Columbia boundary, the Chilkoot Valley, Glacier Bay National Park boundary, and extending south to the Davidson Glacier and the Chilkat Peninsula and Islands (fig A-I). This area was studied as part of the larger JMD study in a cooperative effort between the Alaska Division of Geological and Geophysical Surveys (ADGGS) and the Bureau during 1985 to 1988. Prior to this, during 1984, the ADGGS and the Bureau cooperated in a study of the Porcupine mining area and during 1981 to 1983 conducted separate studies in the area. Field work was conducted by foot, boat, truck, and helicopter. Figure A-I shows the Haines-Klukwan-Porcupine sub-area and shows the areas covered by previous Bureau and ADGGS studies. PHYSIOGRAPHY AND CLIMATE The physiography of the subarea ranges from gentle to rugged. Glaciers formed the major features in the sub-area and left "U" shaped steep walled valleys and rugged mountains. The Chilkat, Chilkoot, Klehini, Tsirku, and Takhin are the major rivers in the subarea. The higher mountains are glacier clad and some valleys still harbor glaciers that reach the valley floors. Lush forests and dense brush predominate up to timberline at about the 2,000-foot elevation. Low point in the subarea is at sea level in the area around Haines while the high point is 7,434 feet at: Mount Henry Clay in the Porcupine mining area.

Jan 1, 2012

By Terry G. Montgomery, Eric S. Weiss, John E. Going, Kenneth L. Cashdollar

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) conducted joint research on dust explosions by studying post-explosion dust samples. The samples were collected after full-scale explosions at the PRL Lake Lynn Experimental Mine (LLEM), and after laboratory explosions in the PRL 20-L chamber and the Fike I m3 chamber. The dusts studied included both high- and low-volatile bituminous coals. Low temperature ashing for 24 h at 515 °C was used to measure the incombustible content of the dust before and after the explosions. The data showed that the post-explosion incombustible content was always as high as, or higher than the initial incombustible content. The MSHA alcohol coking test was used to determine the amount of coked dust in the post-explosion samples. The results showed that almost all coal dust that was suspended within the explosion flame produced significant amounts of coke. Measurements of floor dust concentrations after LLEM explosions were compared with the initial dust loadings to determine the transport distance of dust during an explosion. All these data will be useful in future forensic investigations of accidental dust explosions in coal mines, or elsewhere.