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By T Sprague, D Pateman

"The Gosowong Gold Project is owned and operated by PT Nusa Halmahera Minerals (PT NHM), an Indonesian company 75 per cent owned by Newcrest. It is located on Halmahera Island, in the North Maluku Province of the Republic of Indonesia, approximately 2450 km north-east of the national capital, Jakarta (Newcrest, 2017).Kencana is one of two underground gold and silver mines at the Gosowong Operation where ground conditions vary from competent to very poor. Development headings occurring in poor rock mass conditions require high capacity ground support including long tendon cable bolts. Manual installation of cable bolts in these development headings has been a time consuming process due to borehole collapse, blockages requiring subsequent re-drilling and a minimum eight hour grout curing time interval. The installation of cable bolts including the setting, plating and tensioning can impact the critical path for development heading advance resulting in development cycle delays.A review was conducted by PT NHM on current industry practices for alternatives to manual cable bolting. PT NHM subsequently approached Minova to assist with the development and trialling of self drilling anchors (SDAs) installed using jumbos with a rapid setting pumpable resin, CARBOTHIXTM. A series of system development trials were conducted and a reliable bolting system was developed utilising the existing jumbo drilling fleet with minimal required modifications.The system developed was a ‘one pass’ bolting process to install and grout SDAs using a two component resin with a remote, mechanised system. Improvements achieved from the system include: eliminating hole closure issues and more immediate support in poor rock mass effectively reducing personnel exposure to poor ground conditions by removing the requirement to access the drive backs reducing grout set time with full installation times for 6 m SDAs averaging 25 min.The resin grouting system has now been successfully implemented to effectively manage areas of poor ground conditions and to accelerate advance rates in high priority headings.CITATION:Pateman, D and Sprague, T, 2017. Development and implementation of a long tendon bolting system utilising resin grouting technology, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 79–84 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 16, 2017

By Larry A. Haas

The Bureau of Mines is investigating the use of complex gas mixtures, such as would be produced by coal gasification, for reducing iron oxide pellets. A semiempirical model was developed to predict a priori the reduction rate of an iron oxide pellet in a laboratory tube furnace with simulated coal gases at a total pressure of 1 atm. The model uses partial pressures of H2, CO, CO2, CH4 (methane), water vapor, and a temperature-dependent term to predict the rate of reaction. The reduction rate (weight loss per unit of time) was determined with a thermo-gravimetric apparatus (TGA) in the temperature range of 800° to 1,100° C. The ranking of the reductants, in order of decreasing reducing potential, is H2, CO, and CH4 at temperatures between 800° and 1,000° C; however, CH4 became a better reductant than CO at 1,100° C. Water vapor did not decrease the reduction rate as much as did CO2, Carbon deposition was observed at temperatures below 1,000° C with gas mixtures with high CO and low H2 concentrations. With low-Btu gas at 900° C, over 90 pct of the iron oxide was reduced to iron in less than 3 h. This com-pares with a reduction time of 1.5 h with medium-Btu gas and 1 h with reformed natural gases.

Jan 1, 1985

By Rodney L. Williamson

Optimal estimation theory has been applied to the problem of estimating process variables during vacuum arc remelting (V AR), a process widely used in the specialty metals industry to cast large ingots of segregation sensitive and/or reactive metal alloys. Four state variables were used to develop a simple state-space model of the V AR process: electrode gap (G), electrode mass (M), electrode position (X) and electrode melting rate (R). The optimal estimator consists of a Kalman filter that incorporates the model and uses electrode feed rate and measurement based estimates of G, M and X to produce optimal estimates of all four state variables. Simulations show that the filter provides estimates that have error variances between one and three orders-of-magnitude less than estimates based solely on measurements. Examples are presented that verify this for electrode gap, an extremely important control parameter for the process.

Jan 1, 2001

By V. G. Papangelakis, M. Cheung, M. Dry

The high pressure acid leaching of laterite was modelled and simulated using a combination of two commercially available software packages, namely Aspen Plus 11.1 and the OLI Stream Analyzer. New kinetic parameters for the acid-controlled metal dissolution and precipitation reactions at temperature were first determined from previous experimental data on the leaching of limonite. A grain model with cylindrical pellets was used to model the solid-liquid dissolution reactions. Precipitation reactions were modeled via aqueous equilibrium chemistry. A dedicated thermodynamic database previously developed at the University of Toronto was used in conjunction with the OLI software to model the solution chemistry and calculate the concentration of hydrogen ions in solution at the leaching temperature. Mass balances were handled by Aspen Plus. The simulation gave good predictions of nickel dissolution under industrial and laboratory conditions, for the dissolution of limonite and limonite/saprolite blends. Computational

Jan 1, 2005

By Eldon L. Brown

Location and History The Sherritt Gordon property is located in northwestern Manitoba, about 100 miles north of The Pas and 40 miles northeast of Flin Flon. It is connected with the Manitoba Northern railway, which runs from The Pas to Flin Flon by a branch line, 42 miles in length. The location of the property is shown on the sketch-map, Figure 2. The ore deposit was first discovered by Philip Sherlett, a Cree Indian, in 1922. In 1924 Sherlett's claims lapsed and the ground was re-staked by Carl Sherritt and Dick Madole, and was optioned by them to J. P. Gordon in the summer of 1925. Gordon re-optioned the property successively to three well-known mining groups, one of which did some surface trenching .and put down 28 shallow diamond-drill holes before dropping their option. In the latter part of 1927, a Company known as Sherritt Gordon Mines, Limited, was formed to take over the property, and preparations were made for systematic development work. Preliminary Development In order to fill-in gaps left by the original drilling, a light diamond-drill outfit was flown-in to the property from the Hudson Bay railway in the early fall of 1927. Ten shallow holes were put down before freeze-up .and a considerable amount of surface trenching was completed. Based on the results of the surface trenching and the shallow diamond-drilling, an extensive development campaign was outlined. A winter road, 90 miles in length, was cut from mileage 55 on the Hudson Bay railway, and during the winter of 1927-28 a total of 2,600 tons of freight was hauled-in to the property. This freight included four complete diamond-drill outfits, two complete mining plants, building material for two sets of camps, and supplies for one year's operations, including 105,000 gallons of fuel-oil for Diesel engines.

Jan 1, 1933

By N Clarke, A Barros

Preconcentration of run-of-mine subgrade and marginal ore by screening has the potential to substantially improve the economics of mining, particularly for large, low-grade orebodies, and to reduce environmental impacts. It has recently been the subject of a major research effort by a joint public-private research body, CRCORE. Yet despite this, there appears to have been only one fully commercial installation, at Bougainville Copper Limited in the late 1980s. Two reasons for the limited application are that not all ores have suitable properties and the economics of all pre-concentration processes on low-grade materials are highly sensitive to the precise balance of mass and value recovery and to the pre-concentration process cost, including materials handling. These factors make it imperative to have good test data on the process response of feedstock across the orebody. Collecting that data presents major challenges, which differ for green and brownfields operations. This paper first discusses the approach to preliminary evaluation developed by CRCORE, which relies on testing of coarse rejects or drill chips available from exploration drilling programs. This method is an efficient first step in evaluating an orebody which is deemed geologically to be potentially amenable to screen upgrading, but it does have limitations and must be followed by larger scale work. A suite of methods have been developed by the authors as a result of test work since the 1990s on several projects, supplemented by published data, which aim to provide statistically robust data at lower cost than large scale bulk sampling tests. For greenfields projects, the upgrade response measured on material crushed to -53 mm has been found to correlate closely with ROM ore, with no scale-up required for material with upgrade responses in the range of commercial interest. Large diameter whole drill core, such as PQ, is expected to be suitable for this method. As drilling such core is costly, the aim should be to establish relationships between upgrade performance and proxy measurements such as multi-element chemical or hyperspectral analyses. This approach was successful at the Gramalote gold project in Colombia. The method is not applicable for ores with thick vein material comparable with the crush size, but such material is not suitable for upgrading by screening and would be eliminated by the preliminary testing. For brownfields projects where blasted material can be sampled, the upgrade response can be accurately measured by sampling only the finer fraction of the ore, selecting a top size which represents 30–50 per cent or more of the ROM size distribution. This is likely to be between 50 and 100 mm. The much finer size compared with the full ROM ore greatly reduces the sample mass required to achieve a given intrinsic sampling error and enables sample preparation to be undertaken with large-scale laboratory equipment rather than mobile crushing plant. The accuracy of the method can be improved by measuring the approximate mass of oversize rejected during sampling. Some ores do show a systematic deviation from the assumed model fit which results in this method slightly underestimating the upgrade response, and it would therefore still be recommended to take one or two full bulk samples to confirm results before a final investment decision.

Aug 24, 2022

By Mogens Henriksen

In the past decade, numerous urge scale drilling projects have made use of reverse circulation air lift methods. Reverse air lift pumping can be established by injecting gas into a column of liquid; the subsequently decreased density of the gas-liquid mixture allows atmospheric pressure outside the lift conduit to establish flow. The rate of flow can be controlled by varying the gas to liquid ratio. A typical reverse circulation air lift system is depicted in Figure 1. Allen1 has described a number of reverse air lift drilling projects. Although cited examples are generally related to large diameter holes, the method has seen use in other applications such as sand dredging, chemical pumping, water well pumping and continuous coring. One particular benefit obtained with enclosed reverse circulation drilling is elimination of lost circulation. The required air/water ratio for pumping at a given submergence and lift has been established experimentally by Gibbs2. His data, however, do not reflect sensitivity of flowrate to air/water ratio. Further, in Gibbs' work, air apparently is injected continuously along the column of water. This configuration differs from that used in reverse air lift drilling where air is injected at discrete points only. Gas lift theory has received considerable attention over the past decades. Orldszewski3 defined flow regimes in two phase flow. Griffith and Wallis4 determined relative velocities of gas to liquid. Two-phase flow has been studied extensively for oil transport in inclined and vertical pipes by Chierici et a15, Beggs and Brill6, and Gould, Tek and Katz.7

Jan 1, 1977

Lead Tariff.--The full House Ways and Means Committee approved H.R. 6089 which will have the effect of reducing the tariff on unwrought lead to 3% ad valorem, with a floor duty of 1.0625 cents per pound, compared with the currently effective rate of 3.5% ad valorem. Consideration is also being given to tariff rates on imports of red lead and litharge from Mexico. A consortium of domestic producers has appealed to the Office of the Special Trade Representative (STR) requesting a return to tariff schedules which were in effect prior to the concessions made effective on January 1. Mexican producers have filed a proposal in favor of lower duties, and the matter now awaits a ruling by the STR. Ferrous Scrap Exports.--After holding public hearings and receiving public comments in May, the Department of Commerce announced that it would not institute formal monitoring of ferrous scrap exports, as requested by the Ferrous Scrap Consumers Coalition. The Department said, however, that it would follow the trend of scrap exports and prices. Ferrous scrap prices are currently low and supplies are reported to be adequate.

Jan 1, 1980

By Peter Werner

Technological advances in mine equipment and milling processes have enabled mining companies to exploit ever lower grades of ore. The result has been larger disturbances, greater volumes of waste, a complex web of infrastructure, and an overall trend towards mega-projects that can extend over several square kilometers. This explosive growth in a mining operation’s disturbance footprint provokes an obvious question: What’s it going to cost to reclaim all of this? At face value, this can be an enormous financial liability for a company, but since the timing of reclamation may be years in the future for many operations, these costs can be heavily discounted thereby limiting the burden on the corporate balance sheet. Nonetheless, mining companies are eager to remove these liabilities as quickly as possible, conversely, regulators want assurance reclamation will, in fact, occur. How might one bridge these competing interests? Navigating the practical and financial requirements of a post-closure landscape requires foresight, judgement and assumptions, however, companies who do not adequately plan for these future expenditures when there is no off-setting income stream will likely face some difficult decisions. Simple risk analysis tools and utilizing the time value of money can help bring some clarity to this end-of-mine life phase.

Feb 1, 2025

By G. France

The Blair Athol Coal Mine (BAC) is a large open cut operation in the Bowen Basin of Queensland, Australia. Current mine capacity is about 11 million tonnes per annum (Mtpa) of export coal. On-line analysis at BAC consists of two Coalscan 9500s installed directly on the output of the crusher plant and immediately before the product stockpiles, while a third Coalscan 9500 is installed on the transfer conveyor feeding the train loading bin. The two product Coals cans have a dual purpose. The first is to provide real time coal quality data directly back to the mining operations. The second is that of modeling the product stockpile with accurate on-line information. This modeling enables both production and coal quality personnel to accurately examine the coal quality of each stockpile with a degree of resolution which previously had never been achieved.

Jan 1, 1999

By K L. Olzard

At the WMC Resources Phosphate Hill operation, monitoring the quality of the ore delivered by the mine to the beneficiation plant is of prime importance to ensure the fertilizer is produced cost-effectively through the various stages of production and meets customer quality requirements. P2O5 and Fe2O3 are among the critical-to-quality elements. Fe2O3 is a key performance driver as it is an impurity that adversely impacts some of the chemical processes. The ore is supplied to the plant on a conveyor belt that is equipped with an automatic sampler. Increments are taken off the flowing ore stream at regular time intervals. A variographic experiment was conducted to investigate sampling strategies capable of estimating ore properties over a 12-hour shift to a nominated level of precision. The combination of individual increments into a shift composite was included among the strategies that were assessed. The experiment involved collecting data at regular time intervals and preparing variograms to characterise the feed-grade variability on the conveyor belt. Duplicates were also collected to assist in quantifying the precision of the subsampling stages of the sampling protocol and assay accuracy was monitored with matrix-matched standards. Various sampling schemes were evaluated by combining geostatistical techniques and the sampling theory of Pierre Gy. The following parameters were varied: the number of increments, the increment-size reduction leading to the composite, the masses of the subsequent sampling stages and the number of analytical determinations. This paper describes the planning of the variogram experiment, the various phases of data collection and the methodology used to process the data. It discusses the development of some of the sampling schemes that were considered.

Jan 1, 2005

By N. Ahern, L. Manoukian

"Cyanide is a leaching agent for precious metals commonly used in gold ore processing. Cyanide exists in various forms (including free, complexed as weak or strong complexes, and as ions such as cyanate and thiocyanate), so its detection, speciation and analysis in processing or environmental samples can be complex. This paper will review best practices for cyanide sampling and preservation in the field, interferences and pretreatment methods required prior to sample analysis and analytical methods that are used for cyanide species. Titrimetric, flow injection ligand exchange, spectrophotometric, colorimetric, potentiometric, amperometric, and chromatography techniques will be discussed and their chemistries, detection limits, advantages and limitations will be described.INTRODUCTION Cyanide is well known to be an extremely toxic species. Accurate cyanide measurement in effluent from mines is critical from an environmental perspective. Its measurement is also an important control parameter in the recovery of gold using cyanidation. Cyanide chemistry is diverse and complex, and cyanide analysis can be challenging as a result of and because of limitations in understanding of analytical methods. Various chemical mechanisms can form or destroy cyanide, and the sample matrix or preservation chemicals can also affect analytical results. These interferences make the collection of reliable cyanide measurements challenging and can start as soon as the sample is collected, during laboratory pre-treatment and during analysis. This paper reviews different methods of cyanide measurement. The basic chemistry of cyanide, best practices for sampling and preservation, as well as various methods of analysis will be discussed.CHEMISTRY The complexity of cyanide chemistry is well known (Beck, 1987; Delgado, Botz, Bucknam, Milasovljevic, & Staley, 2008; Botz, Milosavljevic, & Ward, 2013) and is attributed to the ability of cyanide to undergo: •,Volatilization •,Precipitation •,Adsorption •,Complexation with metals •,Oxidation to cyanate, ammonia, or cyanogen chloride •,Reaction with sulfur or sulfide minerals to form thiocyanate •,Redox reactions leading to the formation of cyanogen and cyanate •,Redox reactions (of some cyano complexes) •,Photochemical reactions (of some cyano complexes)"

Jan 1, 2017

By W. V. Bluck

Higher coal quality is being recognized in potentially lowering the cost of power as measured at the bus bar. Assessment of potential coal supplies for most any given power plant is now going beyond buying at the lowest delivered fuel cost and is now taking into consideration other factors such as handling, storage, pulverization cost, boiler fouling, post combustion cleanup, and waste disposal costs. New measurements of quality are being considered now by those producing and those consuming the fuel by assessing numerous variables in the total fuel cycle to achieve the lowest possible power costs.

Jan 1, 1983

The Bureau of Mines has reviewed those portions of the "Tariff Schedules of the United States Annotated 1963" that are of interest to the minerals industry. This study shows to what extent rates of duty were altered (increased or decreased), and provides a bridge where possible from the old Schedule A classification sys tem to the new TSUS system of statistical reporting of import data. In general the new tariff has corrected previous classification defects and inconsistencies, but the rates of duties have not been materially changed.

Jan 1, 1965

By Guodong Li, Chenlin Wang, Zibiao Yu, Bo Xu

Abandoned coal mines have many underground space resources, such as roadways, shafts, and gobs. Among them, abandoned roadways are the best gas storage space for underground compressed air energy storage (CAES). However, CAES caverns have high air pressure and strict sealing requirements. Therefore, the stability and sealing of abandoned roadways under high internal pressure must be analyzed. Afterward, the suitability of abandoned roadways used for CAES caverns should be evaluated. In this study, the numerical simulation software FLAC3D was used to calculate the stress, deformation, plastic zone volume, and pore pressure of surrounding rock in an abandoned roadway under 10 MPa internal pressure. The influence of buried depth, surrounding rock grade, and in situ stress state on roadway stability and the effect of surrounding rock permeability on roadway sealing were analyzed. Results showed that the stress, displacement, and plastic zone volume of surrounding rock were affected by high internal pressure when the buried depth was less than 300 m, but high internal pressure had little effect on them when the buried depth was more than 300 m. The suitable range of buried depth was more than 300 m. The optimal choice of surrounding rock grade was I and II, followed by grades III, IV, and V. The optimal choice of in situ stress state was σH > σh > σv, followed by σH > σv > σh and σv > σH > σh. The sensitivity of the stability evaluation parameters was ranked in descending order as follows: buried depth, surrounding rock grade, and in situ stress state. When the surrounding rock permeability was less than 1 × 10− 14m2, the 24-h air leakage rate of the roadway was less than 1%. The suitable range of surrounding rock permeability was less than 1 × 10− 14m2.

May 23, 2023

By R. Karl Zipf, Z. T. Bieniawski

"Abstract. Based on the premise that understanding the fundamental mechanics of fine fragment formation in coal will lead to reducing coal dust problems in mines, a thorough study of the mechanics of crack propagation in coal was undertaken. Two approaches were considered in an attempt to understand and quantify the fracture process as it relates to fine fragment formation.In one approach, theoretical models are used which describe the size of the fracture process zone which may relate to the amount of structural damage and fine fragment formation on the new crack surface. The other approach is based on the relationship between crack tip stress intensity and new surface appearance for mixed mode crack propagation. Preliminary observations with a scanning electron microscope support the premise that fine fragment formation is related to fracture surface appearance and fracture initiation conditions.An experimental program designed to supply the input parameters for these approaches is presently underway. The experimentation features mixed mode fracture toughness testing, using a special mixed mode testing rig, and fracture velocity measurements with a crack propagation gage. The interpretation of this data via the approaches discussed will provide further understanding of the mechanics of fine fragment formation in coal."

Mar 1, 1989

By Jr. Boyle

This report analyzes the availability of chromium in the form of ferroalloy products (high-carbon and low-carbon ferrochromium and ferrochromium-silicon) and chromite products (metallurgical, chemical, refractory, and foundry sands) in market economy countries (MEC's). A total of 873.5 Mmt of in situ material, containing 202.5 Mmt of chromium, in 10 MEC countries was analyzed for availability as of the January 1989 study date. Extraction and beneficiation of this in situ material would result in 475.4 Mmt of marketable chromite products. As analyzed, 288.5 Mmt of these chromite products would be available for export or for internal chemical and refractory use and 186.9 Mmt would be smelted in-country to produce 74.3 Mmt of high-carbon ferrochromium, 3.9 Mmt of low-carbon ferrochromium, and 2.0 Mmt of ferrochromium-silicon, all available for export. A network flow model, which includes centrally planned economy countries (CPEC's), was also constructed to analyze world chromium supply and demand interactions for the period 1986 through 1994 and to address a hypothetical North American embargo on direct imports of all South African chromium products beginning in mid-1990. The model shows capacity constraints developing in the MEC high-carbon ferro chromium industry in 1987 and a possible subsequent overreaction by the industry in terms of new capacity additions. The results suggest that sufficient chromium is available to North America should an embargo on direct imports from South Africa be imposed by its governments. However, the effect on export revenues in South Africa is relatively small, and timely increases to world ferrochromium, chemical chromite, and foundry sand chromite capacities would be required.

Jan 1, 1993

By Scott W. Hazen

This Bureau of Mines report presents the results of a study and statistical analysis of part of the initial exploration churn-drill sampling and some of the subsequent underground diamond-drill-core sampling in the North are body at the San Manuel copper mine, Arizona. These data were derived from regular exploration and mine sampling, not from special samples obtained solely for statistical analysis. The study was conducted as part of the Bureau's continuing program on sampling-methods research. The major objective of the study was to investigate the feasibility of using the techniques of statistical analysis in evaluating sample and assay data and computing grade and tonnage of Ore from porphyry-type copper deposits. It was recognized that using existing data acquired over a period of several years by different methods would introduce problems and limitations for precise comparisons. However, it was expected that the study would provide some general conclusions and certainly a number of preliminary conclusions on the nature of the mineral characteristics and their effect on sampling procedures, the requirements for sampling deposits of this type, and the comparative results of churn-and diamond-drill sampling in the same area of the deposit. All of this information would be essential for future sampling-methods research for computing grade and tonnage of ore.

Jan 1, 1963

By Tuanhui Wang, Qiwei Wang, Quanrui Liu, Jianhui Xu, Chao Wang, Yu Liu, Yuefeng Li

Rockburst is a highly destructive geological hazard that can cause casualties and equipment damage. To achieve highaccuracy discrimination of rockburst intensity, this article proposes an improved model that addresses the inefficient maximum membership principle used in traditional rockburst fuzzy evaluation models. The stress coefficient σθ/σc, brittleness coefficient σc/σt, and elastic deformation energy index Wet are selected as evaluation indicators for rockburst classification. Subjective and objective weights are obtained using the Delphi method and entropy weight method (EWM). Three types of membership function distribution forms are then used to obtain the membership degrees of each indicator to rockburst grades: trapezoidal membership function (TMF), normal membership function (NMF), and quadratic parabolic membership function (QPMF). Finally, six traditional models and six improved models are established using the maximum membership principle (MMP) and weighted average-maximum membership principle combination evaluation principle (WMP), respectively. Based on the analysis of 100 sets of rockburst field data, the accuracy, precision, recall, and F1-score of the improved evaluation model are increased by 11.3%, 0.097, 0.068, and 0.089, respectively, compared to the traditional model. The Delphi-NMF-WMP model is selected as the best model, with four performance indices reaching 97.0%, 0.979, 0.979, and 0.978. The best model is applied to evaluate the rockburst intensity of the Cangling Tunnel, Dongguashan Copper Mine, and Jiangbian Hydropower Station Diversion Tunnel, with evaluation results consistent with the actual situation, demonstrating the reliability and scientificity of the model.

Feb 28, 2024

By Williams J. A.

"Changes proposed in 1969 to modernize legislation governing the exploitation of mineral deposits in the United Kingdom serve as the basis for a discussion of what is considered to be a desirable framework for future legislative proposals.Proposals with regard to prospecting and exploration, evaluation, and acquisition and exploitation are considered, as are suggestions relating, inter alia, to aerial surveys and land restoration.It is concluded that without legislation along the lines proposed there can be no significant revival of metal mining in Britain."

Dec 30, 1971