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Certain Molybdenum Resources in Indonesia Mineralogical and Processing Study

Sep 13, 2010

The paper considers Aboriginal responses to large-scale mining, including Indigenous attitudes towards land access for exploration and project development. The core question, in which I have been interested for some time (Trigger 1997a; 2000; 2001), is: what are the significant factors affecting responses among Indigenous communities to mining exploration and development project proposals?

Jan 1, 2002

By D Craw, P Lindsay, B Peake

The geochemical properties of Kaiata Mudstone and Brunner Coal Measures are evaluated in order to determine their suitability for placement at the proposed Cypress and existing Stockton mines. Correct scheduling of this waste material is needed in order to prevent sulfide oxidation and the generation of acid rock drainage. The Kaiata Mudstone has both acid generating and acid neutralizing properties. Results from this study and previous research from Kingett Mitchell Ltd (2003), indicate that within the Kaiata Mudstone sulphur content decreases with distance away from the Brunner Coal Measure/Kaiata Mudstone contact, while calcium carbonate content increases; sulphur values range from 0.33 to 4.23 wt %; and the acid neutralizing capacity ranges from 0 to 10.4 wt %. The Brunner Coal Measures have a low capacity to neutralize acid and sulphur content is variable ranging from 0.25 to 3.5 wt %. Appropriate control measures are therefore needed for the Brunner Coal Measures and any Kaiata Mudstone within close proximity to its contact. Tests have been undertaken to develop a rapid field or laboratory procedure to define the potentially acid-forming from the non-acid-forming Kaiata material. Results indicate that paste pH, Net Acid Generation (NAG) and Carbonate Bomb tests are suitable. Results from the Carbonate Bomb Test show a strong relationship with the Acid Neutralizing Capacity (ANC) and the Net Acid Production Potential (NAPP), indicating that this method may efficiently determine non-acid forming material in the field within fifteen minutes. Ongoing research includes kinetic column and shake extraction tests. These tests will quantify what trace elements could be leached from the waste rock and provide information on the usefulness of alkaline producing products such as Bauxsol, Limestone and Cement Kiln Dust.

Jan 1, 2004

Following the Coalbrook Colliery disaster in 1960, Salamon and Munro (1967) established the well known empirical coal pillar strength formula in South Africa. This formula has prevented further violent multiple pillar failures. In 1996, a back analysis of the collapsed and uncollapsed cases in Australia led to the development of the Australian empirical coal pillar strength formulae. The original collapsed and uncollapsed coal pillar database of Salamon and Munro (1967) was updated in 2006. This study introduced various strength formulae for different coalfields and seams in South Africa through back analyses of collapsed and uncollapsed cases. Today, the resultant pillar strength formulae from these previous studies and the behaviour of coal pillars are mostly well understood and applied with confidence. However, it was assumed in the previous studies that the behaviour of pillars is not time dependent; therefore, the formulae established do not provide an associated time to failure of coal pillars. This paper attempts to evaluate the so called 'Geometrical Limits' concept to provide the Australian coal mining industry with a tool to assess the long-term behaviour of bord and pillar workings where the pillars are prone to failure due to spalling of ribs. In order to achieve this outcome, the principles of the safety factor concept and the probability of failure calculated using the coal pillar strength formulae have also been evaluated and practical design examples are presented in this paper.

Nov 25, 2010

Tonnage and grade are the principal reported components of mineral resource estimates but tonnage is a derivative of two more fundamental estimates; volume and bulk density. Typically, most of the effort in a resource estimation study is directed towards grade and volume, yet poor application of bulk density data to resource models can result in significant biases. The impact on tonnage estimates is easily recognised but poor density estimates may also introduce subtle biases into the grade estimates. Methods for measuring bulk density have been discussed previously. This paper focuses on the manipulation of bulk density data and the extension of bulk density from essentially point measurements to block estimates within resource models. Bulk density is a continuous, geologically controlled, spatial variable and should be treated as such. Issues such as combining data from multiple sources, sample support and the interdependence of bulk density and grade estimates must be resolved. The statistical and geostatistical techniques used for grade estimation are, under the right circumstances, equally applicable to bulk density. The importance of bulk density needs to be recognised. With robust raw data and correct estimation procedures, better estimates of bulk density can be obtained and both local and global tonnage and grade estimates can be improved.

Jan 1, 2000

By M Simpson

Greywackes of the greater Auckland Region (Brynderwyn Hills to Hamilton), when considered on a regional scale, have characteristic ranges of physical, mineralogical and other properties. Some properties (eg density, porosity, crushing resistance, clay index) generally cluster and correlate with the basement greywacke facies, regions and terranes recognised by geologists, and their diagenetic/metamorphic level. Other local factors, particularly variations in mineralogical composition, nature of matrix cement, grain size, and degree of weathering may produce aberrant properties. Some of these local variations, when extreme, have the potential to affect the aggregateÆs performance in roading or the concrete industries.   Smectite and the zeolite laumontite are the major deleterious minerals occurring in fresh greywacke rocks of the Auckland region, although weathered rocks may contain halloysite, an expanding member of the kaolin clay mineral group. These minerals, when found in abnormally high levels in greywackes cause expansion effects in the aggregate. Currently there are inconsistencies in the detailed correlation of shrinkage, clay index, clay mineral content and intrinsic expansion data that need further research to resolve them.  

Jan 1, 2007

By T O&apos, Beirne

The paper focuses on explosibility conditions in underground coal mines, the behaviour of explosions from initiating gas ignitions to violent dust explosions and the effectiveness and limits of operation of current designs of passive explosion barriers in suppressing the flame front. Areas of particular emphasis include: passive explosion barriers are not designed to protect personnel in the flame initiation zone and its immediate surroundings; passive dust and water barriers are generally considered ineffective against methane ignitions of the magnitude that can occur at the working face; dispersal of suppressant from passive barriers is adversely influenced by equipment, including conveyor belts, located in the barrier zone; current regulations in Australia do not specify the installation of barriers in all roadways leading to the face, so their use has a limited capacity to contain explosions; a manifest design limitation is that passive barriers are restricted to one operation and are therefore ineffective against repetitive fire gases explosions; and the practice of stone dusting in roadways inbye the barrier zone could conceivably adversely affect the operation of passive barriers. The paper discusses performance evaluations made in full scaleexplosion galleries and the use of alternatives to passive barriers,including the installation of active barriers under some circumstances.

Jan 1, 1997

By K Niyomjinda, B Etschmann

Chatree Gold Mine is currently the only modern day gold mine operating in Thailand, and is situated approximately equidistant from Chiang Mai in the north and Bangkok in the south. Environmental guidelines set by the Thai authorities require Chatree Gold Mine to achieve a Total Cyanide level of 20 ppm or less in the process plant discharge slurry stream prior to release into the tailings storage facility. This paper describes both the initial difficulties faced in achieving compliance on this limit utilising the conventional INCO SO2/Air cyanide destruction system and the subsequent process improvements initiated to both the leaching process and the standard INCO process to achieve the current compliance levels of approximately 99/100 shifts. Improvements were focussed on the dual aspects of reducing the formation of WAD cyanide and ferrocyanide species in the leaching circuit coupled with process changes to improve removal of the ferrocyanide species from solution during the cyanide reduction stage.

Jan 1, 2004

By F P. Hao

Organo-sulphur-based collectors (eg xanthates, dithiocarbamates and dithiophosphates) are widely used in the flotation of sulphide minerals. Xanthates (ROC(=S)Sû), for example, adsorb strongly at sulphide mineral surfaces, in a reaction that is electrochemically coupled with the reduction of dissolved oxygen. One of the oxygen reduction products, hydrogen peroxide, reacts directly with dissolved xanthate, leading to its oxidative decomposition. Experimental work has been conducted, using ethyl xanthate, to understand the molecular mechanism by which hydrogen peroxide reacts with xanthates. A number of degradation products have been identified, some of which have not been reported previously. This oxidative decomposition reaction pathway is discussed in the broader context of xanthate decomposition in flotation systems. One of the identified ethyl xanthate decomposition products, ethyl perxanthate (ROC(=S)SOû), has been observed in the process water of a number of mineral processing operations. The interaction of this molecule with goethite (α-FeOOH) particles, typical of that found in tailings dams, has been studied in more detail using attenuated total reflectance (ATR)-FTIR. The ethyl perxanthate molecule has been found to coordinate to iron (FeIII) at the goethite surface, and undergo a surface-catalysed decomposition process. In the presence of both PbII and goethite, a ternary surface complex is formed, where ethyl perxanthate is coordinated directly to surface adsorbed PbII atoms. The results obtained give some insight into the environmental fate of ethyl xanthate in tailings streams, and a basis on which to consider the environmental importance of such species in tailings dams. Strategies for the destruction of residual xanthate levels in waste water streams are discussed in terms of the likely reaction products.

Jan 1, 2002

Although cyclones have been around in their current form since the early-1890s, there have been some exciting new developments, which have extended their efficiency/operation. These developments have taken place with both dense medium and classification cyclones. The more noteworthy developments are:Inlet designInlet design is the determining factor in classification cyclone capacity and efficiency. The recently developed ribbon inlet with patented pressure bulge has not only resulted in unbelievable increases in capacity, but also in efficiency. Sharpness of separation corresponding to an alpha value of greater than four has been achieved! Secondary offtakeOne of the factors leading to reduced cyclone efficiency is the presence of coarse particles in the cyclone overflow. The secondary offtake has been developed specifically to scavenge these particles from the cyclone overflow with great success. Water injectorThe other major factor resulting in reduced cyclone efficiency is the presence of misplaced fine particles in the cyclone underflow. The water injector, which has been around for many years in various forms, can reduce this short circuit fraction by up to 50 per cent. 3-in-1 cycloneThe 3-in-1 cyclone combines the inlet design, secondary off take and water injector into a single unit resulting in the most efficient classification cyclone available in the market. The RejectorTMIron ore has a high yield to underflow and traditional dense medium cyclones have always been spigot constrained. The Rejector TM is an exciting new development whereby the spigot capacity has been increased substantially. The application of the Rejector TM will result in fewer/smaller cyclones being required for a given duty resulting in efficiency gains and reductions in both operating and maintenance costs.

Jan 1, 2002

Research and Tests on Improving the Technology of Enrichment of the Copper-Molybdenum Ore

Sep 13, 2010

Fine Gravity Separation in the Reflux Classifier, Exploiting a High Shear Rate, Laminar Flow Mechanism The Reflux Classifier is used in the gravity separation of particles over a broad range of particle sizes. The device consists of a fluidised bed zone, with a system of parallel inclined channels above. The inclined channels provide a significant hydraulic advantage over conventional fluidised beds via the so-called Boycott Effect (Boycott, 1920). This paper describes a new advance in fine gravity separation based on the high shear rate and laminar flow profile that arises when closely spaced inclined channels are deployed. As reported recently (Galvin et al, 2009a), a powerful density based separation mechanism develops from this arrangement, suppressing the effects of particle size. In this paper we focus on two areas, firstly the application of the separator in the laboratory for batch fractionation of particles of varying size and density to determine the grade recovery curve and hence the liberation, and secondly the step change in separation performance achieved on a continuous steady state basis when closely spaced inclined channels are used. The variation in the separation density with particle size decreases significantly, and the Ecarte Probable Error (Ep) remains at low levels over a broad size range.

Sep 13, 2010

By G Lumley

PlannersÆ optimism (or maybe commercial necessity) means that most mine plans use equipment rates that are rarely achieved (Lumley and Beckman, 2009). This lack of understanding of what equipment actually moves is causing erroneous equipment forecasts, leading to incorrect mine development plans and economic evaluations. Compounding this problem is a downward trend in actual equipment performance in some areas. Consequently, the presentation of realistic mine plans that are actually achieved in practice is not a common occurrence. However, rational, fact-based mine planning is available to those who want it. Hundreds of millions of cycles of data from open cut mining equipment has been collected from mines around the world since 1992. This unique and highly valuable databank is growing at an exponential rate and is being used by a number of our big miners to support rational and fact-based decision-making. However, neither the use nor the appreciation of the value of this data is universal. There is a challenge to everyone in the mining industry - how do you access value from it? The databank was drilled into and the results analysed for, the Australasian Mining and Metallurgical Operating Practices (AMMOP) publication (Lumley, in press). For this paper the analysis has been extended to include interpretation of trends for draglines, shovels, excavators and trucks. It investigates trends between coal and non-coal mines and across geographic areas. It is known that mining equipment performance in most sections of the industry is falling. This paper attempts to quantify the fall and provide explanations. The trends are analysed to extract the reasons behind the changes and most importantly, what can be done about it.CITATION:Lumley, G, 2012. Understanding trends in performance of open cut mining equipment, in Proceedings Project Evaluation 2012 , pp 203-224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

The dissolution of the naturally occurring mineral zircon (ZrSiO4) is examined after ball milling it with magnesium oxide for up to 100 hours in a laboratory mill. There was little effect on the solubility for the initial two hours where size reduction of the zircon was considered to be the dominant effect. Beyond two hours the dissolution increased as a function of the square root of milling time. X-ray diffraction of the powders did not reveal the identity of the soluble phase. However, a nanocrystalline phase was present after milling and this is thought to be the soluble phase.

Jan 1, 2000

Column Bioleaching of a Low-Grade Nickel-Bearing Sulfide Ore Yellow Mountain Deposit belonging to GobiMin Inc is located in the Chinese Tianshan and Altay orogenic belts, Hami, Xinjiang Province, NW China. Indicated Mineral Resources of its reserve are estimated at 12 million tonnes averaging 0.40 per cent nickel. Mineralogical examination and chemical analysis indicated that the Yellow Mountain ore is a type of high Fe, low Mg and low Ni sulfide ore: the main sulfide minerals are ~8.0 per cent pyrrhotite (Fe1-xS), ~1.0 per cent pentlandite ((Fe, Ni)9S8), ~0.6 per cent chalcopyrite (CuFeS2), ~0.5 per cent pyrite (FeS2), and ~0.2 per cent violarite((Fe, Ni)3S4); the main gangue minerals are ~48 per cent olivine, ~28 per cent antigorite, ~3 per cent chlorite, ~2 per cent talc, ~2 per cent tremolite, and~1.5 per cent magnetite; the chemical analysis of the ore sample are Ni 0.40 per cent, Co 0.016 per cent, Cu 0.24 per cent, Fe 12.4 per cent, S 5.6 per cent, MgO 9.6 per cent, CaO 1.80 per cent, SiO2 48.5 per cent and Al2O3 10.3 per cent. Preliminary results of the shake flask test showed that pyrrhotite is easily leached and the high concentration of ferric iron would hamper the growth of bacteria which will bring a negative impact on the bioleaching conversely. This work aims to set up a method to prevent the negative impact of the ferric ion on the bioleaching of the ore. Two method were combined to prevent the negative impact of the ferric ion, they are adaptation of the mixed bacteria to iron ion and bleeding the off-solution periodically to control the levels of iron ion (depending on the tolerance of the microorganisms to the ferric ion) in the leaching solution. Using a mixed mesophiles composed of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans under room temperature, a nickel recovery of 93 per cent and a cobalt recovery of 85 per cent were achieved in 280 days column bioleaching process with an average nickel concentration in the leaching solution of 2.6 g/L. The results showed that the negative effect of the ferric ion can be successfully controlled and the nickel can be bioleached successfully from theYellow Mountain ore.

Sep 13, 2010

Lean Iron Ore Beneficiation in India

Sep 13, 2010

By P M. Ashley

Antimony (Sb) is an element similar to arsenic that forms anions in surface waters, rather than cations like other metals. Little is known about natural mobility of antimony in the environment. However, recent studies have suggested that antimony has similar toxicity to arsenic. Current New Zealand drinking water guideline values are 3 parts per billion (0.003 mg/l) for antimony and 10 ppb (0.01 mg/l) for arsenic. Antimony occurs principally in stibnite (Sb2S3) in mesothermal vein deposits hosted in low grade metamorphic belts of eastern Australia and southern New Zealand. Many deposits have been mined historically, including one large deposit, at Hillgrove, NSW. Oxidation of stibnite and associated arsenopyrite and pyrite causes local acidification of natural waters but acid is readily neutralised by carbonates in mineralised zones and host rocks, and therefore waters are near-neutral (pH 6-8.5). Antimony dissolves readily in moderately oxidized, near-neutral waters. Experimental stibnite oxidation yielded up to 37 mg/kg (37 000 ppb) dissolved antimony, and mine and tailings dam waters at Hillgrove mine have up to 55 mg/kg (55 000 ppb) dissolved antimony. Natural stibnite can contain >5000 mg/kg arsenic in solid solution and therefore dissolution of stibnite, arsenopyrite and arsenian pyrite also releases arsenic into waters. Resultant dissolved arsenic concentrations are up to 3.6 mg/l (experimental) and up to 7.2 mg/l (mine and tailings dam seepages). Mine and tailings discharge waters have elevated antimony and arsenic where they emerge, but attenuation occurs by deposition of the metals on to amorphous iron oxyhydroxides which can contain >10% each of antimony and arsenic. Historic disposal of mineralised waste rock and tailings into the stream system at Hillgrove has caused contamination of sediments and waters with antimony and arsenic for at least 20 km downstream with effects traceable in sediments for 300 km. Other stibnite-bearing deposits are likely to have analogous environmental effects, particularly from historically-mined sites.

Jan 1, 2002

A major problem in open pit mine planning is to determine the optimum pit limit of the mine. The optimum pit limit is the one with maximum discounted net profit and satisfies technical conditions. A number of optimisation techniques have been proposed for determination of pit limits. Among these techniques, those based on graph theory are suitable to solve the three-dimensional (3D) problem. In this paper, two maximum flow methods named, Dinic's algorithm and Push-Relabel algorithm have been used to find the optimum pit limit of an iron ore mine. This method has been implemented in Gol-e-Gohar iron mine in south east of Iran in order to find the final pit limit. Issues, like properties of the mine and orebody, are studied. These properties include wall slope, sulfur and phosphor grade restrictions. The result shows that these properties have significant effect on the determined pit limit.

Dec 6, 2010

By T Wootton

The Barrytown ilmenite pilot plant was commissioned in two stages using Westport Titanium Project heavy mineral concentrate. The wet concentrator was commissioned on the 17 December 1989 and produced magnetic concentrate from this date.   The Drymill was commissioned on the 27 January 1990 and produced product grade ilmenite successfully from the onset.   The commissioning period was exceptionally short by normal standards and few problems were encountered. This paper concludes with general observations of operations of the pilot plant.

Jan 1, 1990

Recovery Efficiency Study on Ilesha Placer Gold Ore by Flotation Using Locally-Sourced Frothers and Collectors

Sep 13, 2010