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Despite the recovery of approximately six million ounces of alluvial gold from the West Coast of the South Island, New Zealand during the last 140 years, a great deal of this having been obtained via sluice boxes and riffle tables, there has been little advance in riffle table technology during this period. In this paper contemporary riffle table design and current operational practices are examined. Studies of gold loss to undersize tailings are described. In addition recommendations derived from recent research carried out in North America are contrasted with gold saving strategies adopted by West Coast miners.

Jan 1, 1992

By Paul Weir

FOR the first time in 1938, bituminous coal production for the week ending Nov. 19 surpassed that of the corresponding week in 1937, and indexes of industrial activity indicated the possibility that the remaining weeks of 1938 would run ahead of the corresponding weeks of the preceding year. But regardless of this year-end pickup, total production in 1938 was approximately 25 per cent less than in 1937. The estimate of 340 million tons for 1938 places the bituminous industry slightly above the production level of 1933 and approximately 10 per cent above the modem low of 1932. Anthracite production is not subject to the same extent as is bituminous coal to fluctuations arising out of the rate of industrial activity, hence the decline from 1937 has not been so great being approximately 14 per cent under 1937. The estimate for 1938 production is approximately 45 million tons, but this represents the lowest level reached in the last fifty years with the possible exception of several strike years.

Jan 1, 1939

By L Lorenzen, H Muller, L Bernard

Australian companies and consultants are becoming ever more involved in projects in African, South American, East European and Middle Eastern countries. However, significant differences in culture and approach to projects sometimes make these projects challenging for reasons that are not purely technical. Often the challenges are rather related to how the project owner and local authorities perceive the reality. These perceptions and sometimes unrealistic expectations regarding project costs and potential outcomes need to be addressed by the æWesternÆ project developer and consultant.This paper will discuss the specific experience of Snowden in studies commissioned by companies from such countries for the development of very large, low-grade gold deposits in some of the most inhospitable areas in the world. The paper will further review similar projects undertaken in other ænew worldÆ countries and compare these to the initial Snowden experience.As the process operating costs of operations in many of these countries are extremely competitive when compared to the typical Australian operating costs, the paper will review the operating costs and the factors which may be pertinent to a large project of this nature, both in the Australian and the ænew worldÆ context. Will Australian-based operations be able to compete in the global gold market when the gold price softens again, as it will do at some stage in the possibly not-so-distant future?CITATION:Muller, H, Lorenzen, L and Bernard, L, 2013. Challenges of developing low-grade deposits in ænew worldÆ countries from a mining consultantÆs perspective, in Proceedings World Gold 2013 , pp 307-314 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By J. Ran

There are challenges in mining deep tabular ore deposits using the open stoping method, particularly mining remnant panels towards the end of mine life. The remnant panels have experienced stress concentration and are in the failing or post failure state causing drilling and loading difficulties, ground movement, induced seismicity and ground instability problems. As more mines are going deep, without effective ground control management, the mine production will be interrupted and equipment damage and personnel injury are likely to occur. Mining at Falconbridge Lockerby Mine located in the Sudbury Basin was concentrated in the deep zone from late 1990s to 2004. The remnant panels situated approximately from 1800m to 1920m below surface were mined in 2004 before the mine closure. These panels were in the central section of the orebody along strike. The orebody was relatively narrow ranging from 5m to 15m and steep dipping at 70o to 80o. Because of the retreat mining sequence and the mining depth, stress concentration, wall closure and seismicity had caused a number of mining difficulties. Managing these challenges was critical in achieving the mine production target without compromising personnel safety and excavation stability. A comprehensive ground control management approach was adopted to mine the remnant panels at depth. The measures taken included ground movement monitoring, understanding the movement pattern of the footwall rock and selecting appropriate support systems, analyzing seismic monitoring data and defining re-entry protocol, brow support design and restricting access. This paper presents these ground control measures and the experience gained in successfully mining the deep remnant panels at Lockerby Mine.

Apr 1, 2005

By Tianzu Yang, Weifeng Liu, Lin Chen, BOYI XIE, DUCHAO ZHANG, HUI XIAO

In this study, the oxygen-rich bath smelting process of copper dross was simulated using Factsage software. It was found that the two-step simulation results agreed better with the industrial data, especially in the speiss. Bismuth (Bi), lead (Pb), antimony (Sb), arsenic (As) and copper (Cu) contents in the speiss by two-step simulation differed from the industrial data by 0.6, 0.8, 2.6, 7.2 and 8.6 weight percent, respectively. The two-step simulation results indicate that the speiss partitioning of Sb, As and Cu increased from 60.1, 32.3 and 27.5 percent to 81.6, 67.8 and 47.2 percent, respectively, with the smelting temperature increasing from 1,050 to 1,250 °C, while the metal partitioning of Sb and Cu increased from 0 and 2.7 percent to 15.2 and 13.3 percent, respectively, with the separation temperature increasing from 400 to 700 °C.

This article attempts to outline essential features of the Mount Isa ore deposit, to reveal the agencies thought to be responsible for its localization, and to describe methods used for obtaining and applying geological data on a commercial basis. Structural features are emphasized because they have proved the most useful agencies to date in searching for ore. Vertical depth, horizontal width and stratigraphic thickness are used throughout the article, and quantities are quoted in long tons.THE DEPOSITA width of more than two miles of evenly bedded shale of the Mount Isa series (upper pre-Cambrian) lies sandwiched conformably between quartzites. The series strikes N.S. and dips approximately 60° W. Shale is unaltered...Important geological work has been carried out by the Queensland Geological Survey, chiefly by Mr. S. R. L. Shepherd, in co-operation with the Geological Department of Mount Isa Mines Limited. Selected references are The Queensland Government Mining Journal for December, 1931, January, 1932 (Rio Grande Lode); December, 19B2 (Black Rock Lode); October, 1933 (General structure); October, 1936 (Mount Isa Lode).

Jan 1, 1939

By W. W. Wen

A continuous pilot-scale test of the GranuFlow Process was conducted using a screen- bowl centrifuge for the dewatering and reconstitution of column flotation concentrate at a coal preparation plant in Virginia. In this test, a slipstream of the fine-clean-coal slurry from the column flotation concentrate was treated with a bitumen emulsion before dewatering. The treated products from the screen-bowl centrifuge appeared to be dry and in a free-flowing granular form, while the untreated products were wet, sticky, and difficult to handle. Specifically, test results indicated that the average moisture contents of the dewatered coal were 35.7, 35.5, 32.6, 29.9, and 26.5 wt% with Orimulsion additions of 0,0.7,3.2,4.8, and 6.4 wt%, respectively. The handleability and dust reduction of the dewatered coal product were also vastly improved.

Jan 1, 1997

By L. W. T. Weitzel

"This paper reviews the Falconbridge- SMRQ’s Raglan project in northern Quebec and the process that was used in developing its current long-term mine plan. Challenges were many and not only limited to the longevity of the project, numerous ore deposits (both underground and open pit), and a 40 km property strike length. As a result of its remote northern location, other factors such as progressive reclamation, leachable mine waste, water treatment, and waste management were also part of the plan. A combination of modern planning tools were used to formulate the plan including DataMine, Mine 2-4D, AutoMod Simulation, and an Excel-based financial spreadsheet to bring the total plan together. The focus of the paper is to show the complexity of modern mine planning and associated economic modelling of mine processes. IntroductionThe Raglan project is located 1660 km directly north of Quebec at the northern tip of the Quebec Peninsula in Nunavik. The main property is 40 km in length stretching from the Donaldson airport area at the eastern edge of the property to East Lake at the western edge. The Deception Bay port is 90 km north of the main complex/mill situated at Katinniq which lies approximately in the middle of the property (Fig. 1). The mine processes 1 000 000 tpy of ore from both open pit and underground sources. The mill is forecasted this year to produce more than 150 000 t of concentrate grading more than 18% nickel. All personnel and critical cargo are transported to the site via a company-leased 737 jet from Rouyn-Noranda where the main administration office is located. The majority of cargo is shipped to the site via Deception Bay from Quebec and on the return trip, nickel concentrate is shipped back. From Quebec, the nickel concentrate is sent by rail to the Falconbridge smelter in Sudbury and on the reverse rail haul, nickel matte from the smelter is sent to Norway via Quebec."

Jan 1, 2003

By A Asadov, D Nair

This paper discusses the determination of the percentage of crystalline material in a natural silica deposit which would be considered harmful to health (<10 ¦m). A sample of the natural silica material was recovered and split into a number of subsamples. Samples were sieved using a conventional dry sieve to remove material >300 ¦m before testing. Particle size analyses of the fine fraction showed 75 per cent of the material was below 10 ¦m. Initially XRD and XPS were run on the samples to determine the minerals and composition of the sample. The XRD revealed strong quartz peaks and smaller tridymite peaks with a high amorphous background. The XPS indicated traces of iron, titanium and carbon with dominant silicon and oxygen peaks. The structure of the sample was investigated using the SEM. It was apparent that there were a number of larger quartz crystals (>30 ¦m) with a mix of amorphous and crystalline in the finer fraction. It was also observed that amorphous material was attached to the surface of the crystals. In order to determine the percentage of crystalline quartz a known amount of quartz was added to the sample incrementally. On each addition an XRD scan was performed and the area under the peaks recorded. Back analysis of these peaks with an assumed percentage of crystalline material in the original sample gave a crystalline content of 30 per cent. The quantity at the respirable fraction was estimated to be 18.7 per cent.

Jan 1, 2003

By Richard F. Hewlett

Engineers at the Bureau of Mines Denver Mining Research Center have been a research program investigating the theory and application of mine sampling. Part of this program is an investigation of the efficiency of sampling methods that involves development of sampling-method theory through simulating ore-deposit samples and assays, using - electronic digital computer. Theoretical developments are checked against actual ore-deposit sampling, assay, and production data by the commonly used polygonal and triangular methods of computing grade and tonnage of ore reserves. To speed the computing procedures, a program has been developed utilizing a medium-size digital computer for computing ore reserves by the polygonal method. This program calculates nine prismoids per minute at a total cost of $0.21 per prismoid. The complete program, written for an augmented IBM 650 computer, is described in detail; it can be used without change for computing ore reserves for a low-grade deposit. Modifications necessary to convert the program to compute ore reserves for virtually any other type of deposit or grouping of ore horizons also are given; however, the program is limited to using only vertical drill-hole data.

Jan 1, 1962

By P. G. Hallof

Only recently has the term Induced Polarization found its way into geophysical literature. Schlumberger first mentioned the possible use of the induced polarization effect in one of his early papers. Later, induced polarization was the subject of several university theses, such as Seigel's at the University of Toronto and Bliel's at the Michigan School of Technology. In addition, a group at the New Mexico School of Mining and Technobgy has done work on induced polarization. There is very little to be found in print on the subject of induced polarization. Several papers have been presented at meetings, the 1958 AIME and SEG* conventions, for instance, on laboratory measurements of the effect and theoretical considerations useful in the interpretation of field results. This paper is the first attempt to present actual field results which show the usefulness of induced polarization as a prospecting technique. There are several phenomena that can cause polarization when electrical current is passed through the ground. In a paper presented at the 1958 SEG* meetings Professor T. R. Madden of M. I. T. demonstrated that only two of these gave rise to appreciable effects. The first is a result of the membrane and diffusion effects in a sandstone that contains appre- ciable amounts of clay minerals. The unbonded charges associated with the clay mineral forma material that passes positive and negative ions with different mobilities. When current is passed through such a system for some period of time, polarization results. The second phenomenon, which gives rise to very much larger polarization effects, is the one used in the new prospecting technique. These effects are a result of the blocking action or polarization of metallic or electronic conductors in a medium of ionic solution conduction. This electrochemical polarization, called "the over-voltage effect" by electro-chemists, occurs whenever electrical current is passed through a volume of rock which contains metallic minerals such as base metal sulphides. This polarization at metallic interfaces in ionic solutions depends upon the chemical energies necessary to allow the ions to continue the flow of current by giving up or receiving an electron from the metallic surfaces. The energy stored in this reaction isanalogous to that stored when a condenser is charged. If a d. c. current flowing through such a system is interrupted, the polarization can be detected as a small, decaying current that flows after the applied current is discontinued. The decaying potential measured is a result of the current flow caused by charges returning to their equilibrium positions from the positions they assumed under the applied potential field. Because of the polarization, there is an excess of change at each metallic interface. There is an alternate method of measurement of the induced polarization effect. The electrical

Jan 1, 1961

By Nageswararao K

A series of tests was carried out on one of the rock-pebble milling circuits treating complex nickel ores at Kambalda Nickel Operations of Western Mining Corporation. A mathematical model to describe the behaviour of a 508 mm hydrocyclone was developed from the data.A "flat" reduced efficiency curve was observed for the system. This was attributed to a marked difference in the specific gravity of different size fractions of the feed. A modified approach in describing the shape or the reduced efficiency curve resulted in accurate prediction of the hydrocyclone performance.

Jan 1, 1981

The Reefton Goldfield on the West Coast of the South Island of New Zealand was a significant gold producing area between 1860 and 1951. During this period it produced approximately 2.1 million ounces (67 tonnes) of gold. The largest single producer on the goldfield and the deepest mine in New Zealand, was the Blackwater Mine at Waiuta which produced 21 tonnes of gold. The Prolubition Shaft reached a depth of 878 metres (317 metres below sea level). The mine closed suddenly in 1951 with about 66 000 tonnes of are remaining in the stapes. Since closure there has been no attempt to determine the ore potential of the mine at depth. This paper summarises the geology, history and resource potential of the mine and sets out two options for evaluating the remaining resource. The options are either deep drilling from surface or recovery of the Prohibition Shaft and underground development and drilling. A schedule for each option is presented and discussed.

Jan 1, 1992

By G. S. Camm

Gwynfynydd is a small, high-grade black shale-hosted vein-gold deposit. The Chidlaw Link Zone is the only area being mined and contains 24 000 t ore grading 15.2 g/t gold. Within the Link Zone a complex vein structure occurs consisting of a mother vein up to 5 m thick and narrow (less than 0.5 m) leader veins. The former shows minor variations in dip, strike and thickness, whereas the latter show marked changes in all three. The leader veins are hosted within the footwall zone of the mother vein and both are composed of quartz with galena, sphalerite, chalcopyrite, pyrite and minor arsenopyrite. The vein system is transected by a series of cross-vein and intra-vein dip-slip faults. Pockets of gold occur at vein intersections or branches and within the complex footwall zone and are often related to variations in vein attitude and/or geometry. The Chidlaw Link Zone displays a complex, erratic distribution of gold mineralisation and a multi-stage history of structural activity, fluid flow and mineral deposition

Jun 18, 1905

The Effect of High Power Nanosecond Electromagnetic Pulses on Selectivity of Pyrite from Arsenopyrite

Sep 13, 2010

By A J. Rorke, U Chhika

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

Jan 1, 1995

By J C. Waters

Pseudoclastic hydrothermal alteration textures occur within quenched coherent dykes forming part of a subaqueous dome complex (~4 Ma) onPonza Island, Italy. These textures are similar to those observed in considerably older (~500 Ma) subaqueous volcanic rocks at a number of localities throughout the Mount Read Volcanics in Tasmania and elsewhere in ancient volcanic sequences of this type in Australia. This is significant because the processes of formation, hydrothermal alteration and secondary mineralisation of ancient volcanic sequences may be better understood if we can make comparisons with modern analogues. Observations at Ponza imply that these pseudoclastic alteration features form synvolcanically or immediately after dyke emplacement and lava extrusion. This is compatible with scenarios presented for their formation in ancient sequences in the Mount Read Volcanics, Tasmania.

Jan 1, 1995

By F. Agterberg

In his 1978 monograph ‘Lognormal-de Wijsian Geostatistics for Ore Evaluation’, Professor Danie Krige emphasized the scale-independence of gold and uranium determinations in the Witwatersrand goldfields. It was later established in nonlinear process theory that the original model of de Wijs used by Krige was the earliest example of a multifractal generated by a multiplicative cascade process. Its end product is an assemblage of chemical element concentration values for blocks that are both lognormally distributed and spatially correlated. Variants of de Wijsian geostatistics had already been used by Professor Georges Matheron to explain Krige’s original formula for the relationship between the block variances as well as permanence of frequency distributions for element concentration in blocks of different sizes. Further extensions of this basic approach are concerned with modelling the three-parameter lognormal distribution, the ‘sampling error’, as well as the ‘nugget effect’ and ‘range’ in variogram modelling. This paper is mainly a review of recent multifractal theory, which throws new light on the original findings by Professor Krige on self-similarity of gold and uranium patterns at different scales for blocks of ore by (a) generalizing the original model of de Wijs to account for random cuts; (b) using an accelerated dispersion model to explain the appearance of a third parameter in the lognormal distribution of Witwatersrand gold determinations; and (c) considering that Krige’s sampling error is caused by shape differences between single ore sections and reef areas.

Jan 1, 2015

By William R. Yernberg

A conference on coalbed and coal mine methane was held March 27 and 28, 2000, in Denver, CO. The conference, organized by the Strategic Resource Institute, was attended by leaders in the coal mining and gas energy industry. The conference focused on the recovery of methane from coal beds as an energy resource and the removal and utilization of coal-mine methane (CMM) related to underground coal mining. The two-day conference discussed methane resources around the world, methods of recovery, methane markets, underground coal mining, health and safety issues and environmental issues related to methane. The consensus among the presenters is that the future looks promising for coal bed methane (CBM) and CMM.

Jan 1, 2000

By Paul Worsey, Larry Frost, Braden Lusk, Seok Bin Lim

For certification of blast resistant windows, current tests consist of arena tests or large air gun tests. Arena tests involve the detonation of more than 1000 pounds of explosives with windows placed in the range of hundreds of feet. The result of an arena test is a loading on a window consistent with an expected industrial or terrorist blast. Due to the nature of this type of test, only a limited number of facilities are available and operational costs can be extremely high. Air gun tests involve the use of compressed air and a failing diaphragm fired through a large tube. Although this test is more cost effective and easier to administer with lower environmental impacts, it is not an explosive loading and does not create a negative phase on the tail of the pressure pulse. Simply using a small charge in close proximity to the window is not a viable option either. The pressure peak can be reached using this method, but the duration of the pressure pulse is such that the positive phase impulse is on the order of ten times less than that for an arena test.

Jan 1, 2006