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Breakwater Resources Ltd is a Canadian base metals producer with Cu-Pb-Zn operations in Canada, Honduras, and Chile. Two of its operations contain economical gold levels which are recovered in both gravity and flotation concentrates. The gold payable terms in zinc concentrate are poor when compared to gold concentrates or copper concentrates and various flow sheets have been evaluated by Breakwater staff to maximise gold reporting in higher value products. The Myra Falls mine in British Columbia recovers coarse gold in the grinding circuit, part of which is upgraded and sold as a gravity-gold concentrate with the balance being directed to the copper concentrate. A sampling survey showed that there was potential gravity-recoverable gold in the copper regrind circuit. Installing a gravity concentrator in the copper regrind circuit increased the gold grade and recovery in the higher revenue copper concentrate and reduced the quantity reporting to the less well paid zinc concentrate. The El Toqui Mine in southern Chile has distinct high-and low-gold orebodies which are campaigned separately through the flotation plant. The high gold zone yields both a gravity concentrate and an unusual gold flotation concentrate. The gravity concentrate undergoes intensive cyanidation and electrowinning on-site to produce dore, while the fl otation concentrate is sold to gold producers. The zinc concentrate contains signifi cant gold values. The paper describes efforts over the past few years to improve gold returns at Breakwater's operations and highlights the different approaches dictated by the mineralogy of the gold occurrences at these two operations.

Aug 1, 2010

Since 1958 there have been 16 major coal mine explosions in the U.S. claiming 323 lives. Whilst the exact cause of a number of these incidents has not been determined, the majority has involved gas ignitions in one way or another. In addition there have been fatal gas explosions in salt mines and vapor explosions in oil mines. Furthermore, many of the oil shale mines in the U.S. have proven to be gassy giving cause for concern. Compounding these problems is the fact that frictional ignition of methane in coal mines has dramatically increased over the past several years; over 100 such ignitions were reported in 1979. While, no fatalities have been attributed to frictional ignition in the U.S. since early 1978, a recent mine explosion in Nova Scotia which resulted in 11 fatalities was attributed to a frictional face ignition. Research being conducted at the Bureau of Mines is aimed at the prevention and suppression of gas explosions. Emphasis is placed on new coal cutter bits for reducing ignition frequency, machine-mounted water sprays for preventing frictional face ignitions and automatic devices for quenching incipient ignitions and fully developed gas explosions.

Jan 1, 1981

By Harris J. W

Mr. Gillie and Mr. Harris have given us a wealth of information and food for thought on the vital subject of information and food fo rthought on the vital subject of reducing costs and mention considerable saving in some of the larger items. There are a number of points on which I would like further information, but I will confine my remarks to a relatively small saving which is of particular interest in view of another paper to be presented this afternoon.Mention is made of a 50 per cent reduction in the amount of zinc used in the precipitation of gold slime from the pregnant solution. Would Mr. Harris enlarge on the methods by which they obtained this reduction; and could he give an actual figure of zinc consumption either by ton of ore treated or per ounce of bullion recovered.AuthorsWe consider the reduction of zinc is due to improved clarification of the pregnant solutions. The sand clarifiers used prior to the installation of the 50 ft. -thickener were not satisfactory due mainly to the blending of the hessian and matting under the sand. Under these conditions the leaf clarifiers were fed with overflow solution from the clarifiers and were overloaded in consequence. The addition of Calgon has also been beneficial.The present consumption of zinc per ton of solution treated is 088 lb. per ton.A. L. "Keats (No,rth Broken Hill Limited)In the operation of milling equipment there is a progressive increase in maintenance expenditure during the life of a machine, so that when comparing the cost of operating old equipment with the cost of operating new equip...

Jan 1, 1956

By B Beale

Bow-tie analysis is a commonly used tool to identify and display risks that have the potential for an undesired hazardous event. The output of the analysis are bow-tie diagrams, which are an effective and versatile communication format that can be applied to any type of risk. Contrary to their simplicity, a proper bow-tie diagram that maintains its usefulness and clear communication is difficult to build. Over two decades assisting Major Hazard Facilities with bow-tie analysis for Safety Cases, several common mistakes have been identified. This paper aims to highlight those issues with examples and provide improvement strategies. A sample of the most common mistakes are: - overly complicated risk analysis - poorly scoped and defined terms - poor descriptions and justifications - identifying too many dependent controls. Overly complicated risk analysis leads to wasted time in obtaining data for little gain. The bow-tie diagram is only a model. Effort should be redirected into identifying and managing controls that will make a tangible difference to site risk. Broad scopes lead to enormous and confusing bow-tie diagrams for both the user and the workshop team. Defining the scope of the study, the consequence severity of interest and critical control characteristics creates focused workshops and targeted analysis. With more definitive scope, there may be more bow-tie diagrams, however, they are succinct and specific. Well described causes are imperative for clear communication to users, regulators and future bowtie review workshop groups. It is best to use common wording structures and explain the event stepby- step. Also, clearly document any likelihood calculations and use data references where applicable. Identifying all possible controls creates a false sense of security that there are many layers of protection. In reality, most controls are dependent on a single system or person and could all be compromised from a single failure. A definition of a ‘bow-tie’ control is required whereby it must be independent from other controls. Improving the bow-tie analysis process will assist operators in developing meaningful and ‘operational’ bow-tie diagrams to support risk management systems and practices.

Apr 16, 2024

By N Madani

Linear interpolation of geo-related variables is important to different aspects of mining engineering such as long and short-term mine planning. The ore deposit description attained from spatial modeling of blast hole datasets has been widely taken into account, particularly, for short-term mine design and grade control, so as to define the ultimate destination of a mined block. It is approved in practice that making the wrong decision leads to losing a huge amount of money for choosing the destination of a mined block. In the case of complex ore deposits, the issue of estimation of variables in the region is questionable and somehow tedious. Due to this fact, modeling those complications in the co-spatial behavior of the grades in multi-element deposits prompts one to employ enhanced geostatistical techniques. Traditional approaches of this purpose such as polygon, inverse distance weighted and even (co)-kriging approaches, are incapable of reproducing those complexities such as non-linearity, heteroscedasticity and geological constraint that frequently exist among the variables of interest in those deposits. Another difficulty in employing those linear interpolations in grade estimation is smoothing effect, in which the estimated grades are over and under estimated. CITATION: Madani, N, 2018. 3D estimation of variables with complexity in cross-correlation structures, in Proceedings Complex Orebodies Conference 2018, pp 49–52 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By K S. Park, J K. Kim, J H. Park, Y Su

The present study investigates the possibility of the direct removal of oxygen from the Ti-30Ni (wt per cent) alloy melt through the thermodynamic equilibrium reactions at 1623 K in the vertical tube furnace. The deoxidation efficiency of Ti-Ni alloy melt by adding different contents of metallic calcium (Ca) as a deoxidant was evaluated with the binary CaF2-MgCl2 flux. The thermodynamic equilibrium experiments showed that the total oxygen content in the alloy decreased from about 650 ppm to 350 ppm when 3.5 wt per cent Ca was added to the Ti-30Ni (wt per cent) alloy. Alternatively, the effect of flux composition in the CaF2-MgCl2 flux on the oxygen content was also investigated at 1623 K. Therefore, the effect of binary flux systems on the deoxidation ability was compared at 1623 K. According to the results, the flux system with 80 per centCaF2– 20 per centMgCl2 exhibited the best deoxidation capability, ie total oxygen content in the alloy reduced from 1450 to 550 ppm.

Aug 21, 2024

By Davies H, Pigram C, Sunata W, Falvey D, Loxton C, Giddings J, Rogerson R

PALAEOMAGNETIC CONSTRAINTS ON TERRANE TECTONICS IN NEW GUINEA Chris Klootwijkl), John Giddingsl), Wahyu Sunata2), Chris Pigraml), Charles Loxton3), Hugh Daviesl), Rick Rogerson3) and David Falveyl) 1) Bureau of Mineral Resources, Canberra, Australia 2) Geological Research and Development Centre, Bandung, Indonesia 3) Geological Survey of Papua New Guinea, Port Moresby, Papua New Guinea

Jan 1, 1987

By C E. Gawith

The Waihi underground mining operation currently mines epithermal veins ranging from two metres up to ten metres in width using a ‘Modified Avoca’ stoping method. This method consists of longhole bench stope mining at 15m to 18m sublevel spacing. The bulk of production drilling and blasting is top down with the extraction length of a typical stope panel nominally being 18m to 20m along strike. A stope panel is usually taken in two blasting cycles followed by the remote bogging of the stope ore. The panel is backfilled in-cycle using unconsolidated waste rock material which is tipped into the void from the upper level using a Caterpillar R2900 or R1700 sized underground loader. The underground mine first commenced production in 2008 and up until 2016, as was typical of many open stope mining operations at the time, an underground loader was used to place a waste rock bund at the top brow of the open stope. This rock bund was the principal means of protecting people and equipment from this hazard. In 2016 there was a fatality at the mine when a loader that had been tasked with building this rock bund fell into the stope void. Immediately post incident all mining and processing operations were suspended for a week to allow colleagues to grieve, to observe cultural protocols and to begin the investigation into this event. During this period senior operators, supervisory and technical staff developed an innovative system which used steel bollards to protect this open edge. With development over the following months this bollard system has eliminated this hazard from the Waihi underground mine.

Mar 15, 2021

Anglo Coal Australia (ACA) takes a proactive position with regards to attracting and retaining employees at a graduate level. Currently, ACA has graduates in its program across all disciplines: Mining Engineering, Mechanical Engineering, Electrical Engineering, Commercial, Occupational Health and Safety, Environmental Engineering, Human Resources, Safety Engineering and Processing Engineering. The current program is three years in duration and involves two (generally) equal periods at different ACA mine sites or Brisbane Corporate Office. ACA takes an active role in promoting its status at the university level by maintaining a scholarship program. Six undergraduate scholarships are offered each year across all disciplines. Associated Vacation Employment is offered to each scholarship holder during the period of his or her university study. This commitment to education is regarded highly by future graduates. ACAÆs active role in sponsoring student bodies is also known and appreciated amongst the university population. ACAÆs graduate program has been a successful training program for future leaders of the coal mining industry. The company is committed to making the program more suited to the needs of the graduates across all disciplines and as a result the program is not stagnant but is constantly changing and evolving. Recently the æGraduate PassportÆ has been drafted with an aim to keep each graduateÆs needs in relation to experience and training firmly in focus for the duration of the three-year program. Appropriate training for each graduateÆs position is supported by the company; for instance, support through funding and time for a commercial graduateÆs CPA qualifications is provided.

Jan 1, 2005

By T D. H McGrath, R Byleveld, W P. Staunton, J J. Eksteen

"The Gold Technology Group at Curtin University through the AMIRA P420 series of projects has recently developed the integrated liberation leach model (ILLM) for optimisation of gold plants. The model encompasses recovery by both gravity (batch centrifugal concentrators or BCCs) and leach adsorption (CIP/CIL) circuits. The ILLM essentially combines the Group’s well-known standalone models (ie gravity and SIMCIL) to create a robust simulation package.The ILLM process model provides a tool for sites to determine optimum set points for operations to optimise recovery (eg target grind size). It can also be used to predict the effect on gravity recovery, leach recovery and overall recovery when changes are made to circuit design, either temporarily (eg a leach tank taken off-line for maintenance) or as part of a circuit expansion (eg expanded gravity circuit capacity, or addition of leach tank capacity).This paper discusses the capability of the ILLM process model by highlighting a recent case study. The paper also addresses the test work and plant data required as model inputs, as well as limitations and the application of the ILLM to greenfield projects.Citation:McGrath, T D H, Staunton, W P, Eksteen, J J and Byleveld, R, 2016. Application of an Integrated Liberation Leach Model for Process Optimisation, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 173–178 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By M Rispin, R Karlson

Chemical admixtures are not commonly included in the variety of backfill mixes used in the mining industry. This may be attributed to several reasons including, but not limited to: the perceived high added cost, the lack of awareness about their proper use, and the lack of knowledge about their features and benefits. In the construction industry today, however, chemical admixtures are used in the majority of the concrete produced, enabling concrete to become a more cost-effective building material. They also enable construction crews to meet demands for year-round construction, quicker completion of construction projects, and improved concrete properties. The high demand for chemical admixtures in the construction industry has led to numerous innovations in admixture technology in recent years. Some of these chemical admixtures have been found to enhance the production, transport, placement, and in situ properties of backfill mixes. Others have been found to reduce the cost of such mixes while maintaining, and in some cases improving, their physical properties. In this paper, a few of such innovative admixture technologies are discussed. The benefits, imparted by these technologies to backfill mixes as well as performance data on their use in several backfill applications at various mines, are presented.

Jan 1, 1998

By Warren R. P

When the original Mount Gunson joint venture, between CSR and United Uranium ceased operations in December 1971, an intensive ex- ploration campaign was launched to prospect for more ore in the Mount Gunson region. This campaign resulted in the discovery of the Cattle Grid deposit. A comprehensive sampling programme proved the existence of 4.6 million tonnes of ore, at a mean grade of 2.4% Cu, calculated at a 1.0% Cu cut-off. The planning and development programme that followed this discovery included not only the mining and metallurgical aspects of the exploration of the deposit, but also the en- vironmental aspects. Preliminary work included data collection with respect to meteorology, soil types, and existing flora and fauna.

Jan 1, 1976

In September 1980 the N.S.W. Environ- mental Planning and Assessment Act was gazetted. This legislation created a new arena of government involvement in the procedure for obtaining approval to open a new mine, or expand an existing mine in N.S.W. Since 1980 the legislation relating to environmental protection requirements, the procedure for obtaining Development Consent and the nature of relevant government policies have caused considerable confusion on the part of many potential developers. Implementation of the legislation has now become systematic and relatively predictable. However, certain aspects can be improved and require urgent government action.

Jan 1, 1983

By L Neems

In conjunction with Orica Explosives, Worsley Alumina have managed a program of continuous improvement to their cap rock blasting over the last two years. Blasting conditions are challenging because of the hard and shallow nature of the material. Blasting costs must be controlled and the environmental consideration of noise and dust is critical. Worsley have sought to determine the optimum balance between drilling and blasting costs and fragmentation. As the cap rock has few inherent weaknesses, loader productivity is strongly controlled by the degree of fragmentation from blasting. The optimum blasting solution is also constrained by maintaining airblast levels at the surrounding residences below 115 dBL . The major blast design parameters optimised during the program were stemming type, stemming length, powder factor and blasthole diameter. A series of carefully managed trial blasts were fired during 1997 and 1998 to quantify the effect of these parameters. Fragmentation was digitally measured using OricaÆs Powerseive G technique. Shovel productivity, airblast levels and blasting costs were also quantified. As a result of the project, Worsley now have an increased knowledge of the key parameters driving blast performance, and their consequent impact on downstream processes, the environment and total mining cost.

Jan 1, 1999

FOR some time it has been recognised by the Metallurgical Staff that the presence of pyrite in the ore was adversely affecting the grades of the flotation concentrates.Following experimental work, it was decided to change over from the acid circuit in the mill to an alkaline circuit. The following description sets out the procedure adopted, -and the results obtained when such change-over was made.The Zinc Corporation ore consists mainly of galena, marmatite, calcite, and quartz, with smaller quantities of pyrite, fluorspar, and rhodonite.A clean specimen of marmatite picked from the ore assayed 53.4% zinc, and 10% iron, with no lead or insoluble. However, as zinc concentrates have been, at times, produced in the plant assaying over 53% zinc, and with only 8.7% iron, apparently the picked specimen of marmatite did not represent an average composition.The average would probltbly be between 8 and 9% of iron, and from 53.5 to 54.5% of zinc. It is obvious, therefore, that from this ore it is not possible to produce zinc concentrate of a higher grade than this average figure.In the Colorado School of Mines Quarterly for April, 1928, Vol. 23, No. 2, on page 47, we find the following statement:As the zinc in the ore exists as marmatite, which contains approximately 54.5% zinc and 10% iron, 49% zinc in the concentrate may be considered high.This statement refers to the ore treated in the Sullivan concentrator, owned by the Consolidated Mining and Smelting Company of Canada Limited.

Jan 1, 1930

By G Hobart

Laboratory flotation tests were conducted to investigate the role of pH, zinc sulfate and potassium metabisulfite in the flotation of galena and marmatite in the Broken Hill orebody. Marmatite was depressed under alkaline conditions alone, however the addition of the two depressants, either individually or combined, resulted in the greatest selectivity. The use of zinc sulfate under alkaline conditions resulted in good selectivity whilst maintaining a high lead recovery. The addition of potassium metabisulfite under alkaline conditions reduced zinc recovery, but high additions reduced lead recovery. The addition of both depressants at alkaline pH produced the best result, with a lead concentrate of 72.6 per cent at 98 per cent recovery with less than four per cent zinc recovery.

Jan 1, 2005

By S Hancock, B H. Brady, H Muhlhaus

The aims of this paper are to present the governing science, verify the performance and demonstrate the potential engineering applications of a computational simulator for in situ leach mining of non-ferrous minerals. Assuming that the target mineral is deposited either uniformly within rock matrixes (matrix-hosted) or on fracture walls (fracture-hosted), in situ leaching can be treated as reactive flow and transport in geological media (porous media for matrix-hosted ore deposits and fractured media for fracture-hosted ore deposits). Under this treatment, the processes of in situ leach mining for non-ferrous minerals can be quantified through several sets of equations and these coupled equations have been numerically solved. The computational simulator has been applied to the simulations of one-, two-, and three-dimensional in situ leaching cases. The computational simulator, together with laboratory and in situ leaching tests, can be used to:optimise the leaching chemistry; optimise the in situ scale mining operations; scale up the in situ scale test operation to a full-scale mining operation; and evaluate the post-mining environmental restoration plan.

Jan 1, 2000

To reduce the corrosion of a stainless steel crystallizer, caused by accumulation of chloride impurity in the liquor during the crystallization of ammonium sulphate, a strongly basic anion exchange resin in the sulphate form may be used to remove the chloride from the liquor. The spent resin may be regenerated with dilute ammonium sulphate.The ions involved are sorbed by the resin in the order Equation 1. The sorption of chloride from the liquor and the regeneration of the resin depend upon the effect of concentration on the formation of the the ion pair NH6SO4. The sulphate ion dominates sorption from dilute solution of ammonium sulphate containing minor amounts of choride; choride ion dominates sorption from concentrated solution.

Jan 1, 1976

By S Jahn, M Noel, E M. Rykaart, M Pau

Three soil cover test areas were constructed on waste rock backfilled into the Lichtenberg Pit, near Ronneburg Germany. A fourth, uncovered area was included as a control. Each test area measures 50 m by 65 m, and was constructed using full-scale equipment and construction practices. Extensive material sampling and testing was included as part of the construction. Devices were installed in each plot to monitor meteorology, infiltration, run-off, interflow, soil moisture, soil temperature, and soil pore gases. Boreholes were completed in each area and instrumented for temperature, pressure and pore gas sampling to a depth of approximately 60 m. Data from the monitoring instruments have been collected since July 2000, and have been comprehensively analysed and modelled on two occasions. The paper presents an overview of the test area design and instrumentation and the results of the two comprehensive data reviews. The reliability of the various monitoring methods is discussed and experience with several innovative methods is reviewed. The difficulties encountered in modelling the data set using common soil physical models are discussed.

Jan 1, 2003

Prior to the 20th century much of our infrastructure was provided by the private sector. This included toll roads, tunnels and bridges, power supply, transport and water.With the depressions of the 1890s and 1930s and the world wars, much of this infrastructure passed into public ownership. This was certainly the case in Australia as well as many other Western countries.In the last quarter of the 20th century we are seeing a swing back to private sector provision of infrastructure,-resulting'from increased needs for investment in infrastructure due to changes in

Jan 1, 1993